http://www.aece.ro/ AECE - Advances in Electrical and Computer Engineering Journal RSS feed en-us Copyright (C) 2012 www.aece.ro http://dx.doi.org/10.4316/aece.2008.01001 http://dx.doi.org/10.4316/aece.2008.01001 M., ISHIKAWA, We often observe some kind or another of random fluctuations in physical, chemical and social phenomena to a greater or lesser extent. The analysis of influence of such fluctuations on phenomena is very important as a basic problem in various fields including design and planning of controlled systems in control engineering and analysis of option pricing in economics. In this paper, focusing on biological communities, we study the influence of the random fluctuations on predator-prey systems with diffusion. Noting that interaction of phytoplankton and zooplankton is the basis of a food chain in the lake and the ocean, we consider the two-species predator-prey systems consists of phytoplankton and zooplankton. We analyze the influence of the random fluctuations on the spatio-temporal patterns generated by phytoplankton and zooplankton by the numerical simulations. Wed, 02 Apr 2008 00:00:00 +0300 http://dx.doi.org/10.4316/aece.2008.01002 http://dx.doi.org/10.4316/aece.2008.01002 A., NEVADO, L. M., ONATE, J., SANZ, R., ALCALDE, K., SLAVEN, A fully reliable and efficient adaptive control methodology has been long awaited in industry due to the time-varying nature of industrial plants. This paper demonstrates that this kind of adaptive solution is now available and simple to apply by presenting the first application of a methodology called Adaptive Predictive Expert (ADEX) Control in a petrochemical production unit. A description of the plant and the ADEX solution is followed by a comparative analysis of the results obtained with those of the existing conventional PID control. The objectives of the application involving the naphtha splitter at the Puertollano Refinery of Repsol were to establish the viability of ADEX in this environment, increase the quality of the naphtha products by achieving closer compliance with desired specification and maximizing the economic yield. To achieve these objectives it was necessary to enhance the stability of the naphtha splitter by improving control of the principal variables and eliminating a degree of interaction between them which was causing a resonance problem in the column. The application of the ADEX system confirm its viability, demonstrated a marked increase in column stability, significant improvements in levels of control and the elimination of the resonance problems. Wed, 02 Apr 2008 00:00:00 +0300 http://dx.doi.org/10.4316/aece.2008.01003 http://dx.doi.org/10.4316/aece.2008.01003 C., NITU, A. S., DOBRESCU, This paper presents a method for predicting the consumption of energy. The prediction is realized for the energy used for heating, where the thermal comfort has an important role. The equations that define the thermal comfort in function of the weather indicators are also mandatory for the research. Wed, 02 Apr 2008 00:00:00 +0300 http://dx.doi.org/10.4316/aece.2008.01004 http://dx.doi.org/10.4316/aece.2008.01004 A., TAHOUR, H., ABID, A. G., AISSAOUI, In this paper, a fuzzy logic controller (FLC) is designed, based on the similarity between the FLC and the sliding mode control (SMC), for a class of nonlinear system to tackle the nonlinear control problems with modelling uncertainties, plant parameters variations and external disturbances. The proposed scheme gives fast dynamic response with no overshoot and zero steady-state error. To show the validity and the effectiveness of the control method, simulations are performed for the speed control of a switched reluctance motor. The simulation results show that the controller designed is more effective than the conventional sliding mode controller in enhancing the robustness of control systems with high accuracy. Wed, 02 Apr 2008 00:00:00 +0300 http://dx.doi.org/10.4316/aece.2008.01005 http://dx.doi.org/10.4316/aece.2008.01005 V., MAIER, S. G., PAVEL, C. D., MAIER, I., BIROU, The importance of the harmonic analysis and its frequent utilization in different applications impose a complete accuracy. The conditions which provide a correct harmonic analysis are emphasized and analytically justified in this paper. By using an efficient algorithm, a virtual instrument for the harmonics analysis has been realised in LabVIEW by the authors. This program was a very useful and efficient tool in order to emphasize, from the practical point of view, all the errors analytically outlined. The translation of some superior harmonics to inferior order ones represents a possible and harmful phenomenon pointed out as well. Wed, 02 Apr 2008 00:00:00 +0300 http://dx.doi.org/10.4316/aece.2008.01006 http://dx.doi.org/10.4316/aece.2008.01006 N. D., ALEXANDRU, M. L., ALEXANDRU, Based on the fact that spectral shaping of digital data signals is obtained by encoding and that there exist spectrally equivalent digital filters, the method of Justesen was applied to derive digital filters that approximate the power spectral density (p.s.d.) of a code. The (2,2,3) code, which belongs to the class of FAS (Finite Autocorrelation Sequence) codes showing a limited number of values of the autocorrelation function that are not zero, was used as an example. The spectral properties of the (2,2,3) code are thoroughly investigated in terms of autocorrelation function values and p.s.d. both as a function of normalised frequency fn and the probability of a mark p. The prediction coefficients for the digital filter implementations are derived using approximations by Markov processes of the third, fourth and fifth order. The resulting spectra are compared with those of (2,2,3) code. Wed, 02 Apr 2008 00:00:00 +0300 http://dx.doi.org/10.4316/aece.2008.01007 http://dx.doi.org/10.4316/aece.2008.01007 I. A., LETIA, A., MARGINEAN, The key requirement for a service industry organization to reach competitive advantages through product diversification is the existence of a well defined method for building service bundles. Based on the idea that the quality of a service or its value is given by the difference between expectations and perceptions, we draw the main components of a frame that aims to support the client and the provider agent in an active collaboration meant to co-create service bundles. Following e3-value model, we structure the supporting knowledge around the relation between needs and satisfying services. We deal with different perspectives about quality through an ontological extension of Value Based Argumentation. The dialog between the client and the provider takes the form of a persuasion whose dynamic object is the current best configuration. Our approach for building service packages is a demand driven approach, allowing progressive disclosure of private knowledge. Wed, 02 Apr 2008 00:00:00 +0300 http://dx.doi.org/10.4316/aece.2008.01008 http://dx.doi.org/10.4316/aece.2008.01008 D., GOREA, The paper presents an method for dynamically integrating knowledge capabilities into applications.The method consists in the applications cooperating with a dedicated system that provides knowledge via Web Services. We propose such a system, called DeVisa, which collects prediction models from one or more producers and provides prediction services to consumers. The prediction services are further used in decision making or business intelligence processes within the consumer applications. Wed, 02 Apr 2008 00:00:00 +0300 http://dx.doi.org/10.4316/aece.2008.01009 http://dx.doi.org/10.4316/aece.2008.01009 I. A., LETIA, M., COSTIN, The problem of ontology mapping is tackled in the context of MAS and real life ontologies, context that requires an increased degree of dynamism and the ability to handle high amounts of data. Our solution follows the guidelines of lazy mapping, striving to map only what is necessary and only when it is necessary by using lexical based mapping methods combined with proxy ontologies. However, we are not omitting from this endeavor the accuracy of mapping since our twolayer process has FCA as the second mapping step. Wed, 02 Apr 2008 00:00:00 +0300 http://dx.doi.org/10.4316/aece.2008.01010 http://dx.doi.org/10.4316/aece.2008.01010 O., MATEI, The quantity of thoracic radiographies in the medical field is ever growing. An automated system for segmenting the images would help doctors enormously. Some approaches are knowledge-based; therefore we propose here an ontology for this purpose. Thus it is machine oriented, rather than human-oriented. That is all the structures visible on a thoracic image are described from a technical point of view. Wed, 02 Apr 2008 00:00:00 +0300 http://dx.doi.org/10.4316/aece.2008.01011 http://dx.doi.org/10.4316/aece.2008.01011 C. O., UNGUREAN, The aim of the paper is to describe a system for the head gesture recognition developed in the frame of INTEROB project1. The goal of this project consists in developing an interaction based on gestures with information on robotic systems. In the paper we discussed a method for controlling the mouse pointer movements on the screen by recognizing the operator head movements captured by a video camera. In the second part of the paper it is described a fast and accurate method for hand posture recognition in video sequences. Wed, 02 Apr 2008 00:00:00 +0300 http://dx.doi.org/10.4316/aece.2008.01012 http://dx.doi.org/10.4316/aece.2008.01012 R. D., VATAVU, S. G., PENTIUC, L., GRISONI, C., CHAILLOU, We present a simple procedure for modeling shapes and trajectories of points using cubic polynomial splines. The procedure may prove useful for researchers working in the field of pattern recognition that are in the search of a simple functional representation for shapes and which are not particularly interested in diving into the hightheoretical aspects of more complex representations. The use of splines brings in a few advantages with regards to data dimensionality, speed and accuracy of processing, with minimal effort required for the implementation part. We describe several algorithms for data reduction, spline creation and query for which we provide pseudo code procedures in order to demonstrate the ease of implementation. We equally provide measurements on the approximation error and rate of data reduction. Wed, 02 Apr 2008 00:00:00 +0300 http://dx.doi.org/10.4316/aece.2008.01013 http://dx.doi.org/10.4316/aece.2008.01013 V., FRATAVCHAN, D., SHKILNJUK, The paper focuses on the automated traffic rule control system. It examines the basic scheme of the system, basic constituents, principles of constituent interactions, search methods of moving objects, localization, and identification of the license plate. Wed, 02 Apr 2008 00:00:00 +0300 http://dx.doi.org/10.4316/aece.2008.02001 http://dx.doi.org/10.4316/aece.2008.02001 N., MARIAN, S., TOP, Model based development aims to facilitate the development of embedded control systems by emphasizing the separation of the design level from the implementation level. Model based design involves the use of multiple models that represent different views of a system, having different semantics of abstract system descriptions. Usually, in mechatronics systems, design proceeds by iterating model construction, model analysis, and model transformation. Constructing a MATLAB/Simulink model, a plant and controller behavior is simulated using graphical blocks to represent mathematical and logical constructs and process flow, then software code is generated. A Simulink model is a representation of the design or implementation of a physical system that satisfies a set of requirements. A software component-based system aims to organize system architecture and behaviour as a means of computation, communication and constraints, using computational blocks and aggregates for both discrete and continuous behaviour, different interconnection and execution disciplines for event-based and time-based controllers, and so on, to encompass the demands to more functionality, at even lower prices, and with opposite constraints. COMDES (Component-based Design of Software for Distributed Embedded Systems) is such a component-based system framework developed by the software engineering group of Mads Clausen Institute for Product Innovation (MCI), University of Southern Denmark. Once specified, the software model has to be analyzed. One way of doing that is to integrate in wrapper files the model back into Simulink S-functions, and use its extensive simulation features, thus allowing an early exploration of the possible design choices over multiple disciplines. The paper describes a safe translation of a restricted set of MATLAB/Simulink blocks to COMDES software components, both for continuous and discrete behaviour, and the transformation of the software system into the S-functions. The general aim of this work is the improvement of multi-disciplinary development of embedded systems with the focus on the relation between control engineering and software engineering. Mon, 02 Jun 2008 00:00:00 +0300 http://dx.doi.org/10.4316/aece.2008.02002 http://dx.doi.org/10.4316/aece.2008.02002 A., HALLOUCHE, A., TILMATINE, A short-circuit is a serious situation in a circuit. That is why the determination of the fault current during the operation of the IGBT requires suitable gestures in order to realise a better and reliable operation for the power converters. Thus, it is necessary to know the extreme operating limits for these devices since the use of the IGBT in power converters often subjects them to certain significant electric constraints such as, the short-circuit and the turn OFF on the inductive load. This paper presents then a means of protection for a safe and precise shutdown of the fault current in the device. This circuit allows the IGBT to operate without risks, and permits a reduction of the conduction losses in the device without compromising the characteristics of protection of the short-circuit. Mon, 02 Jun 2008 00:00:00 +0300 http://dx.doi.org/10.4316/aece.2008.02003 http://dx.doi.org/10.4316/aece.2008.02003 D., PETREUS, D., MOGA, R., GALATUS, R. A., MUNTEANU, Faced with numerous challenges raised by the requirements of the modern industries for higher power and higher energy, supercapacitors study started playing an important role in offering viable solutions for some of these requirements. This paper presents the surface redox reactions based modeling in order to study the origin of high capacity of EDLC (electrical double-layer capacitor) for better understanding the working principles of supercapacitors. Some application-dependent sizing methods are also presented since proper sizing can increase the efficiency and the life cycle of the supercapacitor based systems. Mon, 02 Jun 2008 00:00:00 +0300 http://dx.doi.org/10.4316/aece.2008.02004 http://dx.doi.org/10.4316/aece.2008.02004 A., KOOCHAKI, S. M., KOUHSARI, G., GHANAVATI, This paper presents a novel method of modeling internal faults in a power transformer. The method leads to a model which is compatible with commercial phasor-based software packages. Consequently; it enables calculation of fault currents in any branch of the network due to a winding fault of a power transformer. These currents can be used for evaluation of protective relays' performance and can lead to better setting of protective functions. Mon, 02 Jun 2008 00:00:00 +0300 http://dx.doi.org/10.4316/aece.2008.02005 http://dx.doi.org/10.4316/aece.2008.02005 M., IVANCHUK, V., BRAJLOVSKYJ, Improvement of an autodyne Nuclear quadruple resonance spectrometer is offered. The change of frequency of oscillatory LC circuit of the spectrometer is carried out in two ways: by varicap and variable capacitor. A processor module for the capacitor and varicap control is developed. The unit allows to scan and measure the level and frequency of the NQR-signal. The unit is controlled by the personal computer. Mon, 02 Jun 2008 00:00:00 +0300 http://dx.doi.org/10.4316/aece.2008.02006 http://dx.doi.org/10.4316/aece.2008.02006 D., MOGA, R. A., MUNTEANU, M., DUMITREAN, M., DOBRA, R., MOGA, The wireless system for remote measurement of tilt measures the tilt angles of an object with respect to the local g-vector and communicates the measurements toward a mobile device able to display them or to transfer them further to a PC or to a PDA. A low cost implementation solution is presented, with references to both the hardware platform and to the main ideas behind the algorithms present in the software. Higher versatility is achieved through avoidance of the need to calibrate the sensor to the local value of the g acceleration, using algorithms in which this value does not appear in the computation process. Mon, 02 Jun 2008 00:00:00 +0300 http://dx.doi.org/10.4316/aece.2008.02007 http://dx.doi.org/10.4316/aece.2008.02007 D., PICOVICI, A. V., CONTIU, A., TOPA, J., NELSON, This article details an experimental system developed to enhance the education and research in the area of wireless networks technologies. The system referred, as Virtual Lab (VL) is primarily targeting first time users or users with limited experience in programming and using wireless sensor networks. The VL enables a set of predefined sensor networks to be remotely accessible and controlled for constructive and time-efficient experimentation. In order to facilitate the user's wireless sensor applications, the VL is using three main components: a) a Virtual Lab Motes (VLM), representing the wireless sensor, b) a Virtual Lab Client (VLC), representing the user's tool to interact with the VLM and c) a Virtual Lab Server (VLS) representing the software link between the VLM and VLC. The concept has been proven using the moteiv produced Tmote Sky modules. Initial experimental use clearly demonstrates that the VL approach reduces dramatically the learning curve involved in programming and using the associated wireless sensor nodes. In addition the VL allows the user's focus to be directed towards the experiment and not towards the software programming challenges. Mon, 02 Jun 2008 00:00:00 +0300 http://dx.doi.org/10.4316/aece.2008.02008 http://dx.doi.org/10.4316/aece.2008.02008 N. T., MELITA, I., POPESCU, S., HOLBAN, We address the problem of collecting and analyzing vast amount of information in medicine and biology, in the light of the revolutionary technological evolution during the last decades. Currently, the methods of achieving information challenge our capacity to sort and process that data. However, we use the methods of machine learning to sort and analyze this information. In this comprehensive review we describe an experiment of analyzing DNA microarrays using a Genetic Algorithm for feature selection. We study how we can establish a causal relationship between a pattern of genic expression and the evolution of pancreatic cancer using a Genetic Algorithm. Mon, 02 Jun 2008 00:00:00 +0300 http://dx.doi.org/10.4316/aece.2008.02009 http://dx.doi.org/10.4316/aece.2008.02009 D., LOGOFATU, The test compaction is one of most important requirement regarding the large scale integration (LSI) testing. The overall cost of a VLSI circuit's testing depends on the length of its test sequence; therefore the reduction of this sequence, keeping the coverage of error prone points, will lead to a reduction of used resources in the testing process. This problem is NP-complete. Consequently an optimal algorithm doesn't have applicability in practice. In this paper we describe an evolutionary algorithm (GATC) and we introduce the term of compaction factor (cf), i.e. the expected percentage of compacted test sequence. GATC provides in praxis better results than a greedy approach (GR) for many configurations. This improvement comes from the freedom to merge randomly pairs of compatible tests for different candidates to solution and keeps the ones with more Don't care positions, thus there is an increased probability to find for them compatible tests in the next stage. Also the C++ implementation was optimized, using compact data structures and the Standard Template Library. Mon, 02 Jun 2008 00:00:00 +0300 http://dx.doi.org/10.4316/aece.2008.02010 http://dx.doi.org/10.4316/aece.2008.02010 V., KOZHEMYAKO, L., TIMCHENKO, A., YAROVYY, The scientific research deals with organization principles of parallel-hierarchical transform for multistage perception and processing, compression and recognition of information in informational structure and computational systems which make use of computational scheme similar to neural. Unified methodological approach was developed for analysis of parallel processes. This approach considers influence of structural hierarchy in dynamics, in other words it tracks processes of spatial areas transformation of correlated and generation of uncorrelated in time elements of generated network, at the time of transition of the network from one stable stage to another. Mon, 02 Jun 2008 00:00:00 +0300 http://dx.doi.org/10.4316/aece.2008.02011 http://dx.doi.org/10.4316/aece.2008.02011 C. A., TANASE, R. D., VATAVU, S. G., PENTIUC, A., GRAUR, Interactive tabletops allow various opportunities for collaborative work as multiple users may interact simultaneously with the same multimedia content. Despite the fact that the interaction is shared and work is carried out collaboratively by multiple users, it is not always clear who interacts and where as there is no way of knowing where users position themselves at the table. We describe in this paper a method for detecting and tracking multiple users around the physical table using a simple solution implemented with a few short-range distance optical sensors. We are thus able to properly address the following questions: How many users are there? Where are they located around the table? Has a new user approached the tabletop or has someone just left? Are two users close to each other? We believe that answering these questions provides new interaction opportunities enriching thus the overall tabletop experience. We discuss possible applications and describe several implementations. Mon, 02 Jun 2008 00:00:00 +0300 http://dx.doi.org/10.4316/aece.2008.02012 http://dx.doi.org/10.4316/aece.2008.02012 C., CERNAZANU, Feature selection is often an essential data processing step prior to applying a learning algorithm. The aim of this paper consists in trying to discover whether removal of irrelevant and redundant information improves the performance of neural network training results. The present study will describe a new method of training the neural networks, namely, training neural networks using input data features. For selecting the features, we used a filtering technique (borrowed from data mining) which consists in selecting the best features from a training set. The technique is made up of two components: a feature evaluation technique and a search algorithm for selecting the best features. When applied as a data preprocessing step for one common neural network training algorithms, the best data results obtained from this network are favorably comparable to a classical neural network training algorithms. Nevertheless, the first one requires less computation. Mon, 02 Jun 2008 00:00:00 +0300 http://dx.doi.org/10.4316/aece.2008.02013 http://dx.doi.org/10.4316/aece.2008.02013 V. G., GAITAN, V., POPA, C., TURCU, N. C., GAITAN, I., UNGUREANU, OPC specifications have considerably contributed to the uniformization and standardization procedures for the software applications gathering process data and exchanging it in a unitary manner. However, this specification does not provide instructions or guidelines on how to achieve the interconnection with field devices. The present article proposes a standardization solution in field networks, which will enable users to gain access to a server with a communication component and several network drivers. Consequently, all engineering aspects related to implementation will be given a uniform interpretation. We will get a uniform engineering of distributed control systems. Mon, 02 Jun 2008 00:00:00 +0300 http://dx.doi.org/10.4316/aece.2008.02014 http://dx.doi.org/10.4316/aece.2008.02014 K., D'HOE, G., OTTOY, J.-P., GOEMAERE, L., De STRYCKER, This paper presents an indoor location estimation system, especially to locate people or objects at room level. First of all a theoretical approach is given. Secondly, a practical case, using our own system, is presented. Our system consists of a ZigBee-based wireless sensor network connected to a central PC. Using the signpost algorithm and considering the behavior of the received signal strength (RSS) through walls, floors and ceilings, we succeeded in developing a reliable indoor room localization system. Mon, 02 Jun 2008 00:00:00 +0300 http://dx.doi.org/10.4316/aece.2008.02015 http://dx.doi.org/10.4316/aece.2008.02015 A., ROMANYUK, A., HAST, Y., LYASHENKO, On devices without battery consuming and specialized hardware for rendering, it is important to improve the speed and quality so that these methods are suitable for real-time rendering. Furthermore such algorithms are needed on the coming multicore architectures. We show how the methods by Gouraud and Phong, the commonly most used methods for shading, can be improved and made faster for both software rendering as well as simple low energy consuming hardware implementations. Moreover, this paper summarizes the authors' achievements in increasing shading speed and performance and a Bidirectional Reflectance Distribution Function is simplified for faster computing and hardware implementation. Mon, 02 Jun 2008 00:00:00 +0300 http://dx.doi.org/10.4316/aece.2008.02016 http://dx.doi.org/10.4316/aece.2008.02016 R., DAMASEVICIUS, V., STUIKYS, Evolution of design methodologies follows a common trail: technology scaling leads to growing design complexity and rising abstraction level in the domain. Introduction of new (higher) abstraction levels emphasizes the importance of reuse and transformations. The design process can be seen as a sequence of high-level transformations from the higher-level specification to the lower-level one. We analyze high-level modeling and metaprogramming techniques for supporting transformations based on domain variability models. Next, we present a reuse evolution model for domain component design at a higher abstraction level to support the transformation-oriented approaches. Finally, high-level modeling techniques (UML-domain language metamodels for domain code generation, parameterized UML classes for template metaprogramming, feature models for explicit representation of variability) for specification of transformations and metaprograms are analyzed. Mon, 02 Jun 2008 00:00:00 +0300 http://dx.doi.org/10.4316/aece.2009.01001 http://dx.doi.org/10.4316/aece.2009.01001 M., DIMIAN, A., GINDULESCU, C., ACHOLO, The present paradigm of magnetic data storage is approaching its fundamental limits for areal storage density, as well as for speed in data processing. As a result, several magnetic recording alternatives, such as spin polarized current assisted recording, precessional switching, toggle switching, heat assisted recording are currently under intense research efforts. This article is aimed at providing a pertinent theoretical analysis of the spin polarized current assisted recording, emphasizing its performance with respect to minimum requirements for switching field. The first analytical derivation of the critical field curve in the presence of spin polarized currents is presented and the results are compared to the classical Stoner-Wohlfarth astroid. The analysis is performed under the framework of the Landau-Lifshitz-Gilbert-Slonczewski equation for describing the magnetization dynamics driven by external magnetic fields and spin polarized currents. Tue, 03 Feb 2009 00:00:00 +0200 http://dx.doi.org/10.4316/aece.2009.01002 http://dx.doi.org/10.4316/aece.2009.01002 S. M., ROSU, G., DRAGOI, M., GURAN, Nowadays, in the European countries more than 95% of the companies are small and medium-sized enterprises (SMEs) and majority of the European Union employees work in these companies. In order to develop intelligent business to become competitive, the enterprises must increase the quality and technologic level of products and services, to have permanent new product or to make old products bettering and to have a good prices policy. These activities request first a large amount of data, information and knowledge collected from all sources and then request transferring knowledge at each enterprise level. Therefore, this work analyses the state of art of the knowledge and knowledge management (KM) and propose KM scenario to support knowledge applications (KApps) development in SMEs. In addition, the paper presents how can be knowledge bases built at the enterprise level. Tue, 03 Feb 2009 00:00:00 +0200 http://dx.doi.org/10.4316/aece.2009.01003 http://dx.doi.org/10.4316/aece.2009.01003 T. N., DURNEA, N. D., ALEXANDRU, UWB-PPM systems were noted to have a power spectral density (p.s.d.) consisting of a continuous portion and a line spectrum, which is composed of energy components placed at discrete frequencies. These components are the major source of interference to narrowband systems operating in the same frequency interval and deny harmless coexistence of UWB-PPM and narrowband systems. A new code denoted as Totally Flipped Code (TFC) is applied to them in order to eliminate these discrete spectral components. The coded signal transports the information inside pulse position and will have the amplitude coded to generate a continuous p.s.d. We have designed the code and calculated the power spectral density of the coded signals. The power spectrum has no discrete components and its envelope is largely flat inside the bandwidth with a maximum at its center and a null at D.C. These characteristics make this code suited for implementation in the UWB systems based on PPM-type modulation as it assures a continuous spectrum and keeps PPM modulation performances. Tue, 03 Feb 2009 00:00:00 +0200 http://dx.doi.org/10.4316/aece.2009.01004 http://dx.doi.org/10.4316/aece.2009.01004 O., URSARU, C., AGHION, M., LUCANU, L., TIGAERU, This paper deals with a novel pulse width modulation (PWM) switching strategy for a voltage source inverter through carrier modification. The proposed discontinuous sine carrier PWM (DPWM1) method, which uses two modified sine waves, has a better spectral quality and a higher fundamental component. This improved waveform has been derived from the original sine PWM technique through the addition of the 17-percent third-harmonic component to the original sine reference. Tue, 03 Feb 2009 00:00:00 +0200 http://dx.doi.org/10.4316/aece.2009.01005 http://dx.doi.org/10.4316/aece.2009.01005 S. A., SAIED, K., ABBASZADEH, In this paper, two new methods for the stator skew are introduced. In contrary with the conventional stator skew, this paper is concentrate on the slot-opening skew. The simula-tion result by finite element shows a considerable reduction in the cogging torque of the motors, the new methods are applied to. Moreover the simulations justify that the back-EMF shape remains trapezoidal for various skew angles in contrary with that in the conventional skew, this fact makes the method highly applicable in BLDC motors. Tue, 03 Feb 2009 00:00:00 +0200 http://dx.doi.org/10.4316/aece.2009.01006 http://dx.doi.org/10.4316/aece.2009.01006 B., ALLAOUA, A., LAOUFI, This paper presents ant manners and the collective intelligence for electrical network. Solutions for Optimal Power Flow (OPF) problem of a power system deliberate via an ant colony optimization metaheuristic method. The objective is to minimize the total fuel cost of thermal generating units and also conserve an acceptable system performance in terms of limits on generator real and reactive power outputs, bus voltages, shunt capacitors/reactors, transformers tap-setting and power flow of transmission lines. Simulation results on the IEEE 30-bus electrical network show that the ant colony optimization method converges quickly to the global optimum. Tue, 03 Feb 2009 00:00:00 +0200 http://dx.doi.org/10.4316/aece.2009.01007 http://dx.doi.org/10.4316/aece.2009.01007 M., REZOUGA, A., TILMATINE, R., OUIDDIR, K., MEDLES, Many experimental and numerical studies were devoted to the electric discharge of air, and some mathematical models were proposed for the critical breakdown voltage. As this latter depends on several parameters, it is difficult to find a formula, theoretical or experimental, which considers many factors. The aim of this paper is to model the critical breakdown voltage in a Sphere-Sphere electrodes system by using the methodology of experimental designs. Several factors were considered, such as geometrical factors (inter-electrodes interval, diameter of the electrodes) and climatic factors (temperature, humidity). Two factorial centred faces experimental designs (CCF) were carried out, a first one for the geometrical factors and a second one for the climatic factors. The obtained results made it possible to propose mathematical models and to study the interactions between the various factors. Tue, 03 Feb 2009 00:00:00 +0200 http://dx.doi.org/10.4316/aece.2009.01008 http://dx.doi.org/10.4316/aece.2009.01008 V., JEYABALAN, S., USA, Partial discharge (PD) is the major source of insulation failure in power transformer. When transformers are subjected to electrical stress during operation, PD can occur. PD identification is an important diagnostic tool for the reliable operation of transformers. The PD signal detection and location is one of the main challenges for system utilities and equipment manufacturers. In this paper energy based correlation method is proposed for locating the source of PD for different pulse durations. Simulation and experiment are performed on lumped physical layer winding to prove the feasibility of the method and also verified with distributed model of 22kV prototype interleaved winding. Tue, 03 Feb 2009 00:00:00 +0200 http://dx.doi.org/10.4316/aece.2009.01009 http://dx.doi.org/10.4316/aece.2009.01009 S., MICLAUS, P., BECHET, I., BOULEANU, R., HELBET, Electromagnetic environment becomes day by day more congested. Radio communication systems in the short range are now part of everyday life, and there is a need to also assess the pollution level due to their emission if we take into account human health and protection. There is consistent scientific evidence that environmental electromagnetic field may cause undesirable biological effects or even health hazards. Present paper aims at giving a view on exposure level due to wireless local area networks (WLAN) emission solely, as part of environmental radiofrequency pollution. Highly accurate measurements were made indoor by using a frequency-selective measurement system and identifying the correct settings for an error-minimum assessment. We focused on analysis of the electric flux density distribution inside a room, in the far field of the emitting antennas, in case of a single network communication channel. We analyze the influence the network configuration parameters have on the field level. Distance from the source and traffic rate are also important parameters that affect the exposure level. Our measurements indicate that in the immediate vicinity of the WLAN stations the average field may reach as much as 13% from the present accepted reference levels given in the human exposure standards. Tue, 03 Feb 2009 00:00:00 +0200 http://dx.doi.org/10.4316/aece.2009.01010 http://dx.doi.org/10.4316/aece.2009.01010 M. R., ISLAM, J., KIM, An energy efficient cooperative technique is proposed for the IEEE 1451 based Wireless Sensor Networks. Selected numbers of Wireless Transducer Interface Modules (WTIMs) are used to form a Multiple Input Single Output (MISO) structure wirelessly connected with a Network Capable Application Processor (NCAP). Energy efficiency and delay of the proposed architecture are derived for different combination of cluster size and selected number of WTIMs. Optimized constellation parameters are used for evaluating derived parameters. The results show that the selected MISO structure outperforms the unselected MISO structure and it shows energy efficient performance than SISO structure after a certain distance. Tue, 03 Feb 2009 00:00:00 +0200 http://dx.doi.org/10.4316/aece.2009.01011 http://dx.doi.org/10.4316/aece.2009.01011 E. C., BOBRIC, G., CARTINA, G., GRIGORAS, The demand characteristic is the most important one in analyzing customer information. In a distribution network, there is in any moment certain degree of uncertainty about busses loads, and consequently, about load level of network, busses voltage level, and power losses. Therefore, it is very important to estimate first of all the load profiles of buses, using available data (measurements effectuated in distribution stations). The results obtained for various distribution stations demonstrate the effectiveness of the present method in overcoming the difficulties encountered in optimal planning and operation of distribution networks. Tue, 03 Feb 2009 00:00:00 +0200 http://dx.doi.org/10.4316/aece.2009.01012 http://dx.doi.org/10.4316/aece.2009.01012 L., TEODOROF, C., NASTASE, I., ANUTI, M., STROE, Based on flow injection techniques, FIMS is fully automated, fast, and cost-effective. The FIMS uses a high-performance single-beam optical system with a low pressure mercury lamp and solar-blind detector for maximum performance. The FIMS-400 has two stepper motor-driven peristaltic pumps for greater flexibility when used with optional accessories. FIMS is fully controlled from a personal computer using WinLab32 for AA software, a true Microsoft Windows-based program with an unparalleled offering of standard features, including a full range of analytical checks and quality control functions. Tue, 03 Feb 2009 00:00:00 +0200 http://dx.doi.org/10.4316/aece.2009.01013 http://dx.doi.org/10.4316/aece.2009.01013 G., RATA, M., RATA, I., GRAUR, D. L., MILICI, This paper presents a solution for the estimation of induction machine rotor speed utilizing harmonic saliencies created by rotor and stator slotting. This solution purposes to add a carrier-signal voltage at the fundamental excitation. We obtain a carrier-signal current that contains the spatial information. The PWM reference voltage is calculated with DSP - ADMC401, from Analog Device. Tue, 03 Feb 2009 00:00:00 +0200 http://dx.doi.org/10.4316/aece.2009.01014 http://dx.doi.org/10.4316/aece.2009.01014 M. H., ZAHARIA, F., LEON, In this paper the design and implementation of an expert speech therapy system is presented. A brief presentation of involved speech therapy process is made. Also the base for designing and implementations of this system is presented too. Tue, 03 Feb 2009 00:00:00 +0200 http://dx.doi.org/10.4316/aece.2009.01015 http://dx.doi.org/10.4316/aece.2009.01015 V., TRIFA, C., MARGINEAN, The paper presents the aspects regarding FEM analysis of a reluctant motor for direct driving of the light electric vehicles. The reluctant motor take into study is of special construction suitable for direct drive of a light electric vehicle. It is an inverse radial reluctant motor, with a fixed stator mounted on front wheel shaft and an external toothed rotor fixed on the front wheel itself. A short presentation of preliminary design is continued with the FEM analysis in order to provide the optimal geometry of the motor and adequate windings. Tue, 03 Feb 2009 00:00:00 +0200 http://dx.doi.org/10.4316/aece.2009.02001 http://dx.doi.org/10.4316/aece.2009.02001 K., D'HOE, A., Van NIEUWENHUYSE, G., OTTOY, L., De STRYCKER, L., De BACKER, J.-P., GOEMAERE, B., NAUWELAERS, This paper presents our research on the influence of metal plates on a radio frequency identification (RFID) loop antenna operating at 13.56MHz. More specific we have tested different types of metal plates near a loop antenna in terms of resonance frequency. The performance of an RFID system strongly depends on the configuration of the antenna. The study shows that the resonance frequency will shift up in a metallic environment, resulting in a failing performance. A solution is presented to avoid the influence of a changing environment around a loop antenna. As an example a loop antenna is designed to prove the increase of stability. Tue, 02 Jun 2009 00:00:00 +0300 http://dx.doi.org/10.4316/aece.2009.02002 http://dx.doi.org/10.4316/aece.2009.02002 D., BASCI, S., MISRA, Web services that are based on eXtensible Markup Language (XML) technologies enable integration of diverse IT processes and systems and have been gaining extraordinary acceptance from the basic to the most complicated business and scientific processes. The maintainability is one of the important factors that affect the quality of the Web services that can be seen a kind of software project. The effective management of any type of software projects requires modelling, measurement, and quantification. This study presents a metric for the assessment of the quality of the Web services in terms of its maintainability. For this purpose we proposed a data complexity metric that can be evaluated by analyzing WSDL (Web Service Description Language) documents used for describing Web services. Tue, 02 Jun 2009 00:00:00 +0300 http://dx.doi.org/10.4316/aece.2009.02003 http://dx.doi.org/10.4316/aece.2009.02003 I., SALOMIE, M., DINSOREANU, C., POP, S., SUCIU, This paper proposes a solution for preserving the cultural heritage by performing knowledge acquisition from historical documents. We developed a system that gathers knowledge by processing the content of historical documents to enable knowledge retrieval as response to ontologically-guided queries. Knowledge acquisition, one of the main workflows in our system, aims to semantically annotate the content of historical documents and to enrich the domain ontology through lexical annotation and knowledge extraction processes. We use two types of rules in knowledge extraction, one dealing with extracting the relevant information from the documents' content and another one for mapping the extracted information to ontology concepts and properties. Our work was validated on documents available in the Cluj County National Archives addressing the Transylvanian medieval history. Tue, 02 Jun 2009 00:00:00 +0300 http://dx.doi.org/10.4316/aece.2009.02004 http://dx.doi.org/10.4316/aece.2009.02004 G., BACHIR, A., BENDIABDELLAH, The authors compare two control strategies for direct AC-AC matrix converters; namely the Venturini method and the scalar strategy control method. The performance comparison of the two strategies is made under unbalanced distorted torque, rotor speed and stator current operation. The simulation of the three-phase matrix converter feeding an induction motor was accomplished by means of the Matlab/Simulink software. This package makes it possible to simulate the dynamic systems in a simple way and in graphic environment. Tue, 02 Jun 2009 00:00:00 +0300 http://dx.doi.org/10.4316/aece.2009.02005 http://dx.doi.org/10.4316/aece.2009.02005 M., BOUNADJA, A. W., BELARBI, B., BELMADANI, This paper proposes the design and implementation of a novel direct torque controlled induction machine drive system. The control system enjoys the advantages of stator vector control and conventional direct torque control and avoids some of the implementation difficulties of either of the two control methods. The stator vector control principal is used to keep constant the amplitude of stator flux vector at rated value, and to develop the relationship between the machine torque and the rotating speed of the stator flux vector. Thus, the machine torque can be regulated to generate the stator angular speed, which becomes a command signal and permits to overcome the problem of its estimation. Furthermore, with the combined control methods, the reference stator voltage vector can be generated and proportional-integral controllers and space vector modulation technique can be used to obtain fixed switching frequency and low torque ripple. Simulation experiments results indicate that, with the proposed scheme, a precise control of the stator flux and machine torque can be achieved. Compared to conventional direct torque control, presented method is easily implemented, and the steady performances of ripples of both torque and flux are considerably improved. Tue, 02 Jun 2009 00:00:00 +0300 http://dx.doi.org/10.4316/aece.2009.02006 http://dx.doi.org/10.4316/aece.2009.02006 A., PLESCA, Fuses are among the best known of electrical devices and there are an extremely large number in use throughout the world. Beside of the advantageous features, the nowadays fuses have certain drawbacks. Therefore, a new type of fuse based on controllable fusing concept is proposed and a study as regards the total clearing time is done. The new concept has been validated through many experimental tests at different current values. The new type of fuse based on controllable fusing concept can be integrated within an overcurrent protection system especially to protect power semiconductors where the Joule integral criterion is better satisfied. Tue, 02 Jun 2009 00:00:00 +0300 http://dx.doi.org/10.4316/aece.2009.02007 http://dx.doi.org/10.4316/aece.2009.02007 O. A., MOUSAVI, M. S., FARASHBASHI-ASTANEH, G. B., GHAREHPETIAN, The analysis of the risk of partial and total blackouts has a crucial role to determine safe limits in power system design, operation and upgrade. Due to huge cost of blackouts, it is very important to improve risk assessment methods. In this paper, Monte Carlo simulation (MCS) was used to analyze the risk and Gaussian Mixture Method (GMM) has been used to estimate the probability density function (PDF) of the load curtailment, in order to improve the power system risk assessment method. In this improved method, PDF and a suggested index have been used to analyze the risk of loss of load. The effect of considering the number of generation units of power plants in the risk analysis has been studied too. The improved risk assessment method has been applied to IEEE 118 bus and the network of Khorasan Regional Electric Company (KREC) and the PDF of the load curtailment has been determined for both systems. The effect of various network loadings, transmission unavailability, transmission capacity and generation unavailability conditions on blackout risk has been investigated too. Tue, 02 Jun 2009 00:00:00 +0300 http://dx.doi.org/10.4316/aece.2009.02008 http://dx.doi.org/10.4316/aece.2009.02008 R. G., BOZOMITU, V., CEHAN, V., POPA, In this paper a new linearization technique using multi-sinh doublet, implemented with a second generation current conveyor is presented. This new linearization technique is compared with the one based on multi-tanh doublets with linearization series connected diodes on the branches. The comparative study of the two linearization techniques is carried out using both dynamic range analysis, expressed by linearity error and the THD value calculation of output current, and the noise behavior of the two analyzed doublets. For the multi-sinh linearization technique proposed in the paper a method which assures the increase of the dynamic range, keeping the transconductance value constant is presented. This is done by using two design parameters: the number of series connected diodes N, which specifies the desired linear operating range and the k emitters areas ratio of the input stage transistors, which establishes the transconductance value. In the paper is also shown that if the transconductances of the two analyzed doublets are identical, and for the same values of N and k parameters, respectively, the current consumption of the multi-sinh doublet is always smaller than for the multi-tanh doublet. Tue, 02 Jun 2009 00:00:00 +0300 http://dx.doi.org/10.4316/aece.2009.02009 http://dx.doi.org/10.4316/aece.2009.02009 T., TUDORACHE, L., MELCESCU, This paper deals with a comparative numerical analysis of performances of several design solutions of induction machines with improved energy efficiency. Starting from a typical cast aluminum cage induction machine this study highlights the benefit of replacing the classical cast aluminum cage with a cast copper cage in the manufacture of future generation of high efficiency induction machines used as motors or generators. Then the advantage of replacement of standard electrical steel with higher grade steel with smaller losses is pointed out. The numerical analysis carried out in the paper is based on 2D plane-parallel finite element approach of the induction machine, the numerical results being discussed and compared with experimental measurements. Tue, 02 Jun 2009 00:00:00 +0300 http://dx.doi.org/10.4316/aece.2009.02010 http://dx.doi.org/10.4316/aece.2009.02010 H., BALAN, R., MUNTEANU, M., BUZDUGAN, I., VADAN, There are virtually no electronic products today that can comply with the conducted emission regulatory requirements without the use of some form of power supply filter being inserted where the power cord exits the product. Sometimes, properly designed transformers can provide inherent filtering, and so can obviate the need for an intentional filter. Mains EMI (electromagnetic interference) filters carry potentially high currents at dangerously high voltages, so care is essential in their choice. The working voltage and current rating of components can be decided once the specification is known. The basic specification should also include mechanical details such as the enclosure size, and the limit of weight. The electrical specification should include the voltage and current rating. In addition the EMC performance and the allowable leakage current should be specified. The electrical specification must also comply with national safety standards. In the Electrical Equipment Laboratory of the Technical University from Cluj-Napoca, we have made studies on several types of EMI filters and have performed procedures for determining their main differential mode characteristics, presented in the paper for a study of case. Tue, 02 Jun 2009 00:00:00 +0300 http://dx.doi.org/10.4316/aece.2009.02011 http://dx.doi.org/10.4316/aece.2009.02011 R., PENTIUC, G., BALUTA, C., POPA, G., MAHALU, The linear induction motors of hybrid structure have a series of particularities and their most precise estimation of practical flows and outlets has a high level of complexity, especially due to the different form of inductor. The personal contribution on theoretical ground is the justification of the relations for the calculation of practical reactances and outlets, which were also validated by the experimental results using the method of effects' overlapping. The theoretical and experimental results confirm the accuracy of methods and greatly confirm the proposed methods. Tue, 02 Jun 2009 00:00:00 +0300 http://dx.doi.org/10.4316/aece.2009.02012 http://dx.doi.org/10.4316/aece.2009.02012 A., JABBARI, M., SHAKERI, A. S., GHOLAMIAN, In this paper, a magnet shape optimization method for reduction of cogging torque and torque ripple in Permanent Magnet (PM) brushless DC motors is presented by using the reduced basis technique coupled by finite element and design of experiments methods. The primary objective of the method is to reduce the enormous number of design variables required to define the magnet shape. The reduced basis technique is a weighted combination of several basis shapes. The aim of the method is to find the best combination using the weights for each shape as the design variables. A multi-level design process is developed to find suitable basis shapes or trial shapes at each level that can be used in the reduced basis technique. Each level is treated as a separated optimization problem until the required objective is achieved. The experimental design of Taguchi method is used to build the approximation model and to perform optimization. This method is demonstrated on the magnet shape optimization of a 6-poles/18-slots PM BLDC motor. Tue, 02 Jun 2009 00:00:00 +0300 http://dx.doi.org/10.4316/aece.2009.02013 http://dx.doi.org/10.4316/aece.2009.02013 D. D., MICU, R., MUNTEANU jr., G. C., CHRISTOFORIDIS, B., MANEA, The accurate calculation of the current densities induced in layered soil by HV transmission lines in normal conditions is one of the most important steps in the study of the electromagnetic interference between transmission lines and underground metallic structures (i.e. metallic gas pipelines). In electromagnetic interference problems, the best way to investigate the soil's behavior as conducting media is to determine the current distribution within ground. The aim of the present paper is to examine the level of influence that soil layers with different resistivity have on the induced current densities. New analytical formulas for the induced current densities in the two-layer soil case are derived. The determined formulas contain semi-infinite integral terms which are calculated through a stable and efficient numerical integration scheme, in order to overcome the problems arising from the oscillate form of the infinite integrals. In the second part of the paper, the author's contribution relates to the exposure and implementation of a robust Monte Carlo simulation method, in an original approach, for solving ill-posed synthesis magnetic or electric field problems. Tue, 02 Jun 2009 00:00:00 +0300 http://dx.doi.org/10.4316/aece.2009.02014 http://dx.doi.org/10.4316/aece.2009.02014 M. N., LAKHOUA, The aim of this paper is to present firstly the functionality of a supervisory system for complex processes, and secondly to present the concepts of SCADA (supervisory control and data acquisition) systems. A functional analysis technique SADT (Structured Analysis and Design Technique) has been applied on an example of a SCADA system of a thermal power plant. This technique allows a functional description of a SCADA system. The paper briefly discusses the functions of a SCADA system and some advantages of the application of functional analysis for the design of a human centered supervisory system. Then the basic principles of the SADT technique applied on the SCADA system are presented. Finally, the different results obtained from the SADT technique are discussed. Tue, 02 Jun 2009 00:00:00 +0300 http://dx.doi.org/10.4316/aece.2009.02015 http://dx.doi.org/10.4316/aece.2009.02015 L., TEODOROF, C., NASTASE, I., ANUTI, M., STROE, The proper choice of a measurement technique is only one step in the development of a successful application. All steps leading up to the measurement are equally important to the sampling and the sample preparation process begins at the point of collection and extends to the measurement step. The sample preparation method used to convert the sample into a form suitable for the measurement step can have a greater effect on the overall accuracy and reability of the results and the measurement itself. Sample preparation is one of the important problems in analytical process. The microwave digestion coupled with ICP MS measurements, for the heavy metals analysis is a very useful tools for the environmental samples. Tue, 02 Jun 2009 00:00:00 +0300 http://dx.doi.org/10.4316/aece.2009.02016 http://dx.doi.org/10.4316/aece.2009.02016 N. D., ALEXANDRU, S., POHOATA, This paper investigates a novel approach for constructing a family of ISI-free pulses produced by improved Nyquist filters with a transfer characteristic derived from an ideal staircase frequency characteristic using interpolation with sine functions. They equal or outperform some recently proposed pulses in terms of ISI performance in the presence of sampling errors. The results for error probability outperform the 4th degree polynomial pulse for a reasonable number of interpolation intervals. The proposed pulses were also investigated for OFDM use including DVB systems in order to reduce their sensitivity to frequency offset. The results presented in this paper equal those of recently found pulses in terms of intercarrier interference (ICI) power. Tue, 02 Jun 2009 00:00:00 +0300 http://dx.doi.org/10.4316/aece.2009.02017 http://dx.doi.org/10.4316/aece.2009.02017 I., VADAN, H., BALAN, R., MUNTEANU, The paper presents the design and Finite Element (FEM) analysis of a Linear compressor of voice coil type (LCVCT). This kind of linear compressor will be used in a refrigerator equipment. It is well-known that the replacing of the rotating compressor from a classical refrigerator by a linear compressor leads to an efficiency improving wit about 5% by avoiding the piston side friction, which is very important because of the huge number of refrigerators in operation world-wide. The linear compressor refrigerator is already commercially available in South Korea, equipped with an electromagnetic (fix coil and moving permanent magnet) linear compressor. This paper presents a new type of linear compressor - a voice-coil type (fixed permanent magnet and moving coil). The operation principle is the same as for electrodynamic vibrator or electro-dynamic loud-speaker. The designing with rare earth permanent magnet is not a simple problem, because of the nonlinear characteristic of rare earth magnets. A magneto-static FEM analysis has been performed in order to validate the design methodology proposed in the paper. Tue, 02 Jun 2009 00:00:00 +0300 http://dx.doi.org/10.4316/aece.2009.03001 http://dx.doi.org/10.4316/aece.2009.03001 C., PETRESCU, R., OLARU, The paper presents an analytical method for the determination of the magnetic force produced by a mini - actuator with permanent magnets. The results are compared with those obtained by performing a numerical field analysis with COMSOL Multiphysics, showing a very good agreement. The study reveals that the actuator has two equilibrium points, one of which is stable and the other one unstable. Mon, 26 Oct 2009 00:00:00 +0200 http://dx.doi.org/10.4316/aece.2009.03002 http://dx.doi.org/10.4316/aece.2009.03002 Z., HUANG, Y., FANG, X., XIE, M., PAN, Recently, more and more geospatial data are generated and distributed with the promising data acquirement techniques like satellite imaging and digital cartography. So, it is an important issue to effectively make use of these huge geospatial data resources. This means that effective data processing technologies need to be developed to support distributed query and analysis operations onto the distributed resources. The emergence of grid computing technology offers a good solution to accomplish this goal. To combine the grid computing technique with geospatial database we design and implement a GGDS (Grid Geospatial Database System) prototype named GEOBARN. Key modules and detailed implementation methods of GEOBARN are discussed in this paper. By using the GEOBARN system, both reliable data management and effective distributed geospatial query can be achieved. Mon, 26 Oct 2009 00:00:00 +0200 http://dx.doi.org/10.4316/aece.2009.03003 http://dx.doi.org/10.4316/aece.2009.03003 S., POSTALCIOGLU OZGEN, This paper contains graphical user interface (GUI) aided online fault diagnosis for DC motor. The aim of the research is to prevent system faults. Online fault diagnosis has been studied. Design of fault diagnosis has two main levels: Level 1 comprises a traditional control loop; Level 2 contains knowledge based fault diagnosis. Fault diagnosis technique contains feature extraction module, feature cluster module and fault decision module. Wavelet analysis has been used for the feature extraction module. For the feature cluster module, fuzzy cluster has been applied. Faults effects are examined on the system using statistical analysis. In this study Fault Diagnosis technique obtains fault detection, identification and halting the system. In the meantime graphical user interface (GUI) is opened when fault is detected. GUI shows the measurement value, fault time and fault type. This property gives some information about the system to the personnel. As seen from the simulation results, faults can be detected and identified as soon as fault appears. In summary, if the system has a fault diagnosis structure, system dangerous situations can be avoided. Mon, 26 Oct 2009 00:00:00 +0200 http://dx.doi.org/10.4316/aece.2009.03004 http://dx.doi.org/10.4316/aece.2009.03004 I.V., PLETEA, M., PLETEA, D., ALEXA, N., LUCANU, In this paper, a new topology for a two-quadrant converter is presented. In the AC/DC transfer mode, the converter works as a rectifier with near sinusoidal input currents (RNSIC), while in the DC/AC transfer mode it works as a square-wave pulse switching inverter. We offer some suggestions for the converter design and realize a comparison with a two-quadrant PWM converter. The new converter is characterized by smaller power losses, reduced EMI problems and higher reliability. Mon, 26 Oct 2009 00:00:00 +0200 http://dx.doi.org/10.4316/aece.2009.03005 http://dx.doi.org/10.4316/aece.2009.03005 H., VAHDAT-NEJAD, K., ZAMANIFAR, As the scale of Grid platforms grows, the idea of a centralized scheduler loses its efficiency, and it is replaced with the scheme of decentralized schedulers. However, a new problem emerges in distributed scheduling systems, which is how to coordinate the autonomous schedulers to avoid the occurrence of conflicting schedules. In this paper, by exploiting the idea of randomized algorithms, a new scheduling scheme has been proposed, which addresses the problem of scheduling conflicts. The proposed algorithm is thoroughly decentralized in the sense that there is no central point of contact in the system. In addition, our approach is a suitable way toward reaching scalability and autonomy in future Grids. We prove the feasibility and effectiveness of the proposed algorithm through statistical analysis. Mon, 26 Oct 2009 00:00:00 +0200 http://dx.doi.org/10.4316/aece.2009.03006 http://dx.doi.org/10.4316/aece.2009.03006 L., STANESCU, D., BURDESCU, The paper presents original ways of using topic maps for information structuring and retrieval in medical e-learning domain. The topic map is mainly used for graphical visualization of the MeSH thesaurus containing medical terms. The hierarchical structure of the descriptors from MeSH thesaurus that has also multiple associative and equivalence relationships between medical terms can be properly visualized in this way. The topic map is built and populated using an original algorithm, by mapping an xml file that can be downloaded for free to an xtm file that contains the topic map. The paper also presents how to use the topic map for semantic querying of a multimedia database with medical images that are accompanied by diagnosis and treatment as important information. For retrieving the interest information for student, this access path can be combined with another modern solution: the content-based visual query on the multimedia medical database using primitive features like color and texture. Mon, 26 Oct 2009 00:00:00 +0200 http://dx.doi.org/10.4316/aece.2009.03007 http://dx.doi.org/10.4316/aece.2009.03007 P., TORKZADEH, M., ATARODI, A multi-band CMOS LC Quadrature Voltage Control Oscillator (QVCO) with minimum power consumption is developed to meet the phase noise and frequency band requirements of RFID, Zigbee and Bluetooth standards. To accomplish the multi-band receiving architecture at low power consumption, current switching technique with optimized cross-coupled transistor sizes has been used. A comprehensive analysis of small signal model for complementary architecture including transistor noise sources and their effects on output phase noise amount has been discussed. Using extracted small signal model, coupled and coupling transistor sizes for minimum power consumption and the least achievable phase noise have been optimized. Designed QVCO has been implemented using TSMC 0.18um CMOS technology operating at 1.8V supply voltage. Proposed QVCO generates two separated frequency bands of 1.65-1.85GHz and 2.4-2.5GHz with phase noise of -125dBc/Hz at frequency offset of 3MHz. The total current drawn by QVCO is 7.5mA which makes the power consumption as low as 13.5mW. Mon, 26 Oct 2009 00:00:00 +0200 http://dx.doi.org/10.4316/aece.2009.03008 http://dx.doi.org/10.4316/aece.2009.03008 J., KIM, H., TRONG ANH, 5.9 GHz advanced dedicated short range communications (ADSRC) is a short-to-medium range communication standard that supports both public safety and private operations in roadside-to-vehicle and vehicle-to-vehicle communication environments. The core technology of physical layer in ADSRC is orthogonal frequency division multiplexing (OFDM), which is sensitive to timing synchronization error. In this paper, a robust and low-complexity timing synchronization algorithm suitable for ADSRC system and its efficient hardware architecture are proposed. The implementation of the proposed architecture is performed with Xilinx Vertex-II XC2V1000 Field Programmable Gate Array (FPGA). The proposed algorithm is based on cross-correlation technique, which is employed to detect the starting point of short training symbol and the guard interval of the long training symbol. Synchronization error rate (SER) evaluation results and post-layout simulation results show that the proposed algorithm is efficient in high-mobility environments. The post-layout results of implementation demonstrate the robustness and low-complexity of the proposed architecture. Mon, 26 Oct 2009 00:00:00 +0200 http://dx.doi.org/10.4316/aece.2009.03009 http://dx.doi.org/10.4316/aece.2009.03009 A. D., POTORAC, Voice data packets have to arrive at the destination in time, with a defined cadence and with low and constant delay in order to allow the real time voice reconstruction. From this point of view, transmitting voice over IP networks is the most sensitive category of applications, especially when wireless medium is involved. The paper discusses the possibilities of transmitting the maximum number of simultaneous voice streams over 802.11 wireless networks considering the main factors which impact with VoIP throughput, in a basic scenario. Starting from a proposed communication model, the number of simultaneous possible VoIP sessions is calculated, taking into consideration the contribution of the protocol overheads, the security overheads, the PHY level timings and the CODEC proprieties. Numerical results are generated and compared. Mon, 26 Oct 2009 00:00:00 +0200 http://dx.doi.org/10.4316/aece.2009.03010 http://dx.doi.org/10.4316/aece.2009.03010 M., ISTRATE, A., MIRON, C., ISTRATE, M., GUSA, D., MACHIDON, The increased accuracy into the fault's detection and location makes it easier for maintenance, this being the reason to develop new possibilities for a precise estimation of the fault location. In the field literature, many methods for fault location using voltages and currents measurements at one or both terminals of power grids' lines are presented. The double-end synchronized data algorithms are very precise, but the current transformers can limit the accuracy of these estimations. The paper presents an algorithm to estimate the location of the single-phased faults which uses only voltage measurements at both terminals of the transmission lines by eliminating the error due to current transformers and without introducing the restriction of perfect data synchronization. In such conditions, the algorithm can be used with the actual equipment of the most power grids, the installation of phasor measurement units with GPS system synchronized timer not being compulsory. Only the positive sequence of line parameters and sources are used, thus, eliminating the incertitude in zero sequence parameter estimation. The algorithm is tested using the results of EMTP-ATP simulations, after the validation of the ATP models on the basis of registered results in a real power grid. Mon, 26 Oct 2009 00:00:00 +0200 http://dx.doi.org/10.4316/aece.2009.03011 http://dx.doi.org/10.4316/aece.2009.03011 N., MITROVIC, V., KOSTIC, M., PETRONIJEVIC, B., JEFTENIC, This paper focuses on the application of adjustable speed induction motor drives for gantry cranes. Modern solution considers application of frequency converters for all drives. Multi-motor drives are standard solutions in crane application and requirements of load sharing are present. Presented algorithm provides load sharing proportional to the rated motor power on the simple and practically applicable method on the basis of estimated torques by frequency converters, and controller realized in PLC. Special attention is devoted to wide span gantry drive and algorithm for skew elimination. Solutions for load distribution in multi-motor drive, as well as mode of gantry drive skew elimination, are described. Suggested solution concept is confirmed by the experimental results. Mon, 26 Oct 2009 00:00:00 +0200 http://dx.doi.org/10.4316/aece.2009.03012 http://dx.doi.org/10.4316/aece.2009.03012 S.M., LAJEVARDI, Z. M., HUSSAIN, Facial expression recognition has numerous applications, including psychological research, improved human computer interaction, and sign language translation. A novel facial expression recognition system based on hybrid face regions (HFR) is investigated. The expression recognition system is fully automatic, and consists of the following modules: face detection, facial detection, feature extraction, optimal features selection, and classification. The features are extracted from both whole face image and face regions (eyes and mouth) using log Gabor filters. Then, the most discriminate features are selected based on mutual information criteria. The system can automatically recognize six expressions: anger, disgust, fear, happiness, sadness and surprise. The selected features are classified using the Naive Bayesian (NB) classifier. The proposed method has been extensively assessed using Cohn-Kanade database and JAFFE database. The experiments have highlighted the efficiency of the proposed HFR method in enhancing the classification rate. Mon, 26 Oct 2009 00:00:00 +0200 http://dx.doi.org/10.4316/aece.2009.03013 http://dx.doi.org/10.4316/aece.2009.03013 R. D., RUGESCU, The new unit histogram concept is described as increasing with one order of magnitude the amount of statistical information extracted from experimental data. The new statistical technology is particularly suited for very scarce population samples, when it dramatically increases the information extracted from the available data. Otherwise, existing features of the population would remain inaccessible. The method could prove useful also for signal processing, when a high level of accuracy in detail rendition is required. The efficiency of the method is demonstrated in examples of experimental measurement of the combustion heat delivered by rocket propellants. Populations as small as of six readings, where the regular statistics is useless, are successfully processed and characterized. Mon, 26 Oct 2009 00:00:00 +0200 http://dx.doi.org/10.4316/aece.2009.03014 http://dx.doi.org/10.4316/aece.2009.03014 V., CHIFU, I., SALOMIE, Web service composition is mandatory when complex functional requirements cannot be satisfied by a single Web service. Because of the exponential growth of available Web services, their automatic discovery and composition are highly desirable tasks. This paper presents a new approach for automatic Web service composition based on the formalism of Fluent Calculus using semantic service descriptions. In our approach, the Web service composition process is viewed as an AI planning problem in the Fluent Calculus formalism. To semantically describe Web services, we have used a Web service domain ontology which is then translated into a Fluent Calculus knowledge base, necessary for the composition planning phase. For verifying the composed services, the Label Transition System Analyzer (LTSA) formalism is used. The paper also presents an experimental prototype for the Fluent Calculus based Web service composition and demonstrates its effectiveness with the help of an application scenario from the social event planning domain. Mon, 26 Oct 2009 00:00:00 +0200 http://dx.doi.org/10.4316/aece.2009.03015 http://dx.doi.org/10.4316/aece.2009.03015 B., ABDI, J., MILIMONFARED, J., SHOKROLLAHI MOGHANI, A., KASHEFI KAVIANI, Electro-mechanical batteries have important advantages as compared with chemical batteries, especially in low earth orbit satellites applications. High speed slotless external rotor permanent magnet machines are used in these systems as Motor/Generator. Proper material and structure for space applications are introduced. A simplified analytic design method is given for this type of machines. Finally, the optimization of machine in order to have maximum efficiency and minimum volume and weight are given in this paper. Particle swarm optimization is used as the optimization algorithm and the finite element-based simulations are used to confirm the design and optimization process and show less than 1.2% error in parametric design. Mon, 26 Oct 2009 00:00:00 +0200 http://dx.doi.org/10.4316/aece.2009.03016 http://dx.doi.org/10.4316/aece.2009.03016 A., EBRAHIMZADEH, A., KHAZAEE, This work describes a Radial Basis Function (RBF) neural network method used to analyze ECG signals for diagnosing cardiac arrhythmias effectively. The proposed method can accurately classify and differentiate normal (Normal) and abnormal heartbeats. Abnormal heartbeats include left bundle branch block (LBBB), right bundle branch block (RBBB), atrial premature contractions (APC) and premature ventricular contractions (PVC). This paper proposes a three stage, preprocessing, feature extraction and classification method for the detection of ECG beat types. In the first stage, ECG beats is normalized to a mean of zero and standard deviation of unity. Feature extraction module extracts wavelet approximate coefficients of ECG signals in conjunction with three timing interval features. Then a number of radial basis function (RBF) neural networks with different value of spread parameter are designed. We compared the classification ability of five different classes of ECG signals that were achieved over eight files from the MIT/BIH arrhythmia database. Mon, 26 Oct 2009 00:00:00 +0200 http://dx.doi.org/10.4316/aece.2009.03017 http://dx.doi.org/10.4316/aece.2009.03017 I.A., LETIA, A., GROZA, Real arguments are a mixture of fuzzy linguistic variables and ontological knowledge. This paper focuses on modelling imprecise arguments in order to obtain a better interleaving of human and software agents argumentation, which might be proved useful for extending the number of real life argumentative-based applications. We propose Fuzzy Description Logic as the adequate technical instrumentation for filling the gap between human arguments and software agents arguments. A proof of concept scenario has been tested with the fuzzyDL reasoner. Mon, 26 Oct 2009 00:00:00 +0200 http://dx.doi.org/10.4316/aece.2009.03018 http://dx.doi.org/10.4316/aece.2009.03018 R.T., CHEVERESAN, S., HOLBAN., Computer system performance is a very complex process in which the hardware and software manufacturers invest important human and financial resources. Workload characterization represents an essential component of performance analysis. This paper presents a trace based methodology for software applications evaluation. It introduces a new analysis concept designed to significantly ease this process and it presents a set of experimental data collected using the new analysis structure on a representative set of scientific and commercial applications. Several important conclusions are drawn regarding workload characteristics, classifications and runtime behavior. This type of data is used by the computer architects in their efforts to maximize the performance of the hardware platforms these applications are going to execute on. Mon, 26 Oct 2009 00:00:00 +0200 http://dx.doi.org/10.4316/aece.2009.03019 http://dx.doi.org/10.4316/aece.2009.03019 K., LAROUSSI, M., ZELMAT, M., ROUFF, The simplicity of traditional regulators makes them popular and the most used solution in the nowadays industry. However, they suffer from some limitations and cannot deal with nonlinear dynamics and system parameters variation. In the literature, several strategies of adaptation are developed to alleviate these limitations. In this paper, we propose a combination of two strategies for PI parameters supervision and adaptation. We apply the obtained structure to the control of induction machine speed. Simulation and experimental results of the proposed schema show good performances as compared to two strategies. Mon, 26 Oct 2009 00:00:00 +0200 http://dx.doi.org/10.4316/aece.2010.01001 http://dx.doi.org/10.4316/aece.2010.01001 I.-A., VIOREL, L., STRETE, K., HAMEYER, A simple construction of a modular transverse flux generator with permanent magnets in the rotor is proposed in the paper. The specific technology is detailed and an analytical design algorithm is developed. A simplified model is proposed for calculating the machine heating and three dimensions magnetic flux calculation via finite element method (FEM) is carried on in order to check the main generator characteristics. Sat, 27 Feb 2010 00:00:00 +0200 http://dx.doi.org/10.4316/aece.2010.01002 http://dx.doi.org/10.4316/aece.2010.01002 N., ROMAN, E., CEANGA, I., BIVOL, S., CARAMAN, The paper tackles with thickness control structure of the cold rolled strips. This structure is based on the rolls position control of a reversible quarto rolling mill. The main feature of the system proposed in the paper consists in the compensation of the errors introduced by the deficient dynamics of the hydraulic servo-system used for the rolls positioning, by means of a dynamic compensator that approximates the inverse system of the servo-system. Because the servo-system is considered variant over time, an on-line identification of the servo-system and parameter adapting of the compensator are achieved. The results obtained by numerical simulation are presented together with the data taken from real process. These results illustrate the efficiency of the proposed solutions. Sat, 27 Feb 2010 00:00:00 +0200 http://dx.doi.org/10.4316/aece.2010.01003 http://dx.doi.org/10.4316/aece.2010.01003 Z. N., MILIVOJEVIC, M. D., MIRKOVIC, S. M., MILIVOJEVIC, In this paper the fundamental frequency estimation results of the MP3 modeled speech signal are analyzed. The estimation of the fundamental frequency was performed by the Picking-Peaks algorithm with the implemented Parametric Cubic Convolution (PCC) interpolation. The efficiency of PCC was tested for Catmull-Rom, Greville and Greville two-parametric kernel. Depending on MSE, a window that gives optimal results was chosen. Sat, 27 Feb 2010 00:00:00 +0200 http://dx.doi.org/10.4316/aece.2010.01004 http://dx.doi.org/10.4316/aece.2010.01004 A., PLESCA, A., SCINTEE, In many cases when a power assembly based on power semiconductors is used, catastrophic failure is the result of steep temperature gradient in the localized temperature distribution. Hence, an optimal heatsink design for certain industrial applications has become a real necessity. In this paper, the Pro/ENGINEER software with the thermal simulation integrated tool, Pro/MECHANICA, has been used for thermal study of a specific power semiconductor assembly. A series of steady-state and transient thermal simulations have been performed. The experimental tests have confirmed the simulation results. Therefore, the use of specific 3D modeling and simulation software allows to design special power semiconductor assemblies with a better thermal transfer between its heatsink and power electronic components at given operating conditions. Sat, 27 Feb 2010 00:00:00 +0200 http://dx.doi.org/10.4316/aece.2010.01005 http://dx.doi.org/10.4316/aece.2010.01005 Z., WANG, Y., ZHANG, J., ZHANG, J., MA, In this paper, we adopt a novel approach to the fault analysis of complex electric power systems. Electric power system is one of the most complex artificial systems in the world. Its safe, steady, economical and reliable operating plays a very important part in guaranteeing socioeconomic development, and even in safeguarding social stability. The complexity of electric power system is determined by its characteristics about constitution, configuration, operation, organization, etc. No matter if, we adopt new analytical methods or technical means, we must have a distinct recognition of electric power system itself and its complexity, and increase analysis continuously, operation and control level. In this paper, utilizing real-time measurements of phasor measurement unit, based on graph theory and multivariate statistical analysis theory, we are using mainly Breadth-first search, Depth-first search and cluster analysis. Then, we seek for the uniform laws of marked changes of electrical quantities. Then we can carry out fast and exact analysis of fault component. Finally, we can accomplish fault isolation. According to line fault and bus-bar fault (single-phase fault, phase-to-phase fault and three-phase fault) in complex electric power systems, we have carried out a great deal of simulation experiments and obtained ideal results. These researches have proven that the faults in complex electric power systems can be explored successfully by analysis and calculation based on graph theory and multivariate statistical analysis theory. Sat, 27 Feb 2010 00:00:00 +0200 http://dx.doi.org/10.4316/aece.2010.01006 http://dx.doi.org/10.4316/aece.2010.01006 A., SIMION, On the basis of the mathematical model, called in total fluxes in a previous paper, and which is proper for the analysis of transient operation of the two-phase induction machine, one obtains the symmetrical steady-state equations, which are valid for three-phase machines, as well. The obtained mathematical expressions are much more simple and easier to use than the consecrated ones, which are generally applied in scientific literature. Moreover, considerations are to be made upon the space-time rotational vectors, emphasizing their importance in understanding the physical phenomena that characterize induction machines. The use of these space vectors is further tested out for the study of unsymmetrical supply, which gives a much faster method in obtaining the electromagnetic torque expression. Finally, the results are compared with the ones that come out from the traditional methods, more exactly, the symmetric component method. Sat, 27 Feb 2010 00:00:00 +0200 http://dx.doi.org/10.4316/aece.2010.01007 http://dx.doi.org/10.4316/aece.2010.01007 M. R., BANAEI, A.-R., KAMI, This paper presents a novel linearized Phillips-Heffron model of a power system installed with an Interline Power Flow Controller (IPFC) in order to studying power system stability. In addition, a supplementary controller for a novel modeling IPFC to damp low frequency oscillations with considering four alternative damping controllers is proposed. In this paper selection of effectiveness damping control signal for the design of robust IPFC damping controller to variations in system loading and fault in the power system are discussed. The presented control scheme not only performs damping oscillations but also the independent interline power flow control can be achieved. MATLAB simulation results verify the effectiveness of the IPFC and its control strategy to enhance dynamical stability. Sat, 27 Feb 2010 00:00:00 +0200 http://dx.doi.org/10.4316/aece.2010.01008 http://dx.doi.org/10.4316/aece.2010.01008 M. D., TOPA, I., MURESAN, B. S., KIREI, I., HOMANA, This paper presents a method to cancel the echoes generated by reflections in a room. The starting point is the full-band adaptive system identification method, where the unknown system is the room, providing several reflections of the sound. A sub-band filtering method is proposed and all the aspects regarding the filter banks, the structure, the number of sub-bands and the order of the required filters are analyzed. The performance is studied with respect to the provided error and the echo return loss enhancement. The asymmetric structure sub-band filtering offers a better performance than the full-band implementation. Increasing the number of sub-bands will also enhance the performance of the system. Sat, 27 Feb 2010 00:00:00 +0200 http://dx.doi.org/10.4316/aece.2010.01009 http://dx.doi.org/10.4316/aece.2010.01009 M., MONFARED, H., RASTEGAR, H. M., KOJABADI, In this paper a simple and high performance power control strategy for four-switch three-phase converters is developed. Compared to already available control schemes, the proposed controller is very simple to derive and implement; however, it is established on a strong mathematical approach based on the knowledge of the system model. The required converter voltage in each sampling period is directly calculated based on reference and measured values of reactive and active powers, system parameters, and the measured voltage of AC source. Then, the reference voltage is synthesized by a PWM block. Simulation results confirm the effectiveness of the proposed method in providing precise power control with minimum distortion and harmonic noises (THDi), and at the same time, low distortion in active and reactive powers. Sat, 27 Feb 2010 00:00:00 +0200 http://dx.doi.org/10.4316/aece.2010.01010 http://dx.doi.org/10.4316/aece.2010.01010 G., VENKATESAN, R., ARUMUGAM, A Switched Reluctance Motor (SRM) drive is a variable speed motor drive system with unique characteristics. The switching of voltage into the phase winding and pulsating AC input current leads to low power factor and high harmonic contents. In this paper, the power factor is improved using boost converter. The hardware results are taken for a DC input voltage of 60 V to the SRM with different load currents. From the results, it is found that the total current harmonic distortion and individual current harmonics are less with Power Factor Controller (PFC). The power factor of the circuit is improved with the proposed power factor controller. Sat, 27 Feb 2010 00:00:00 +0200 http://dx.doi.org/10.4316/aece.2010.01011 http://dx.doi.org/10.4316/aece.2010.01011 N. D., ALEXANDRU, M. L., ALEXANDRU, This paper presents a comparative analysis of two families of improved Nyquist filters with a piece-wise parabolic frequency characteristic. Their construction is based on a novel approach and produces ISI-free pulses that shows comparable or better ISI performance in the presence of sampling errors, as compared with some recently proposed pulses. The coordinates of the junction points that delimit the parabolic pieces were determined in order to produce a minimal value of the error probability when the impulse response is sampled with a fixed time offset that accounts for the imperfect synchronization in the receiver. With a minor exception both families outperform the poly filter, so far considered the best one. Sat, 27 Feb 2010 00:00:00 +0200 http://dx.doi.org/10.4316/aece.2010.01012 http://dx.doi.org/10.4316/aece.2010.01012 A., JABBARI, M., SHAKERI, A., NABAVI NIAKI, An iron pole shape optimization method to reduce cogging torque in Interior Permanent Magnet (IPM) motors is developed by using the reduced basis technique coupled by finite element and design of experiments methods. Objective function is defined as the minimum cogging torque. The experimental design of Taguchi method is used to build the approximation model and to perform optimization. This method is demonstrated on the rotor pole shape optimization of a 4-poles/24-slots IPM motor. Sat, 27 Feb 2010 00:00:00 +0200 http://dx.doi.org/10.4316/aece.2010.01013 http://dx.doi.org/10.4316/aece.2010.01013 G., ANTONESEI, C., TURCU, A., GRAUR, During the last decade there was an explosion in the field of mobile multimedia devices that led to the emergence of new and very complex requirements for the producers of integrated circuits (IC's). Practically, many of the difficulties localized in the systems made with multiple discrete IC's have moved one level down, inside the IC itself (this is how the concept of System on Chip came up). This paper presents exactly such an example in which the audio section of a mobile phone must coexist with the intermediate radio frequency section in a single IC. It starts by mentioning the technical challenges facing this request, followed by an introduction of the fundamental theories used in finding the most efficient solution. Sat, 27 Feb 2010 00:00:00 +0200 http://dx.doi.org/10.4316/aece.2010.01014 http://dx.doi.org/10.4316/aece.2010.01014 S. S., SHAMSHIRBAND, H., SHIRGAHI, S., SETAYESHI, The goal of rescuer Multi agent's project is to simulate urban unpleasant incidents and events to reduce the rate of detriment of this event. The various rescuer forces attempt to do their best duties. One of the most important problems in multi agent system is communication among agents. Most of the various algorithms in multi agent system so far has share of duties, negotiation, learning and searching need to various forms of communication among agents. In the paper we attempt to rescue the most wounded using Reinforcement learning to be able to gain the shortest time. Sat, 27 Feb 2010 00:00:00 +0200 http://dx.doi.org/10.4316/aece.2010.01015 http://dx.doi.org/10.4316/aece.2010.01015 C.-G., HABA, This paper presents a system that can extend the use of PLC simulator software in real world experiments. The system is composed of a software and a hardware part. The software is designed to monitor the simulator user interface, to provide user-like inputs to this interface and to exchange data with the hardware part. The hardware is used to interface the simulator running on a PC with external input and output devices. Input signals are converted into inputs for the simulated design; outputs from the simulated design are converted into output signals that control output devices connected to the hardware part. The system can work with various types of simulators and can be used in university labs to design and test digital control systems with low to moderate complexity. Sat, 27 Feb 2010 00:00:00 +0200 http://dx.doi.org/10.4316/aece.2010.01016 http://dx.doi.org/10.4316/aece.2010.01016 S. D. R., SURESH, S., USA, Recognition of multiple partial discharge (PD) sources in high voltage equipment has been a challenging task until now. The work reported here, aims to recognize multiple PD sources in oil-impregnated paper using Cluster Analysis (CA) and Fuzzy Logic (FL). The typical sources of PD in transformer are identified and the corresponding single source PD defect laboratory models are fabricated. From the measured PD signals, the necessary statistical parameters are extracted by applying CA for classification. A Fuzzy based algorithm has been developed to recognize single source PDs. The developed algorithm has also been applied to recognize multiple PD sources. Sat, 27 Feb 2010 00:00:00 +0200 http://dx.doi.org/10.4316/aece.2010.01017 http://dx.doi.org/10.4316/aece.2010.01017 A., PATELLI, L., FERARIU, The nonlinear systems identification method described in the paper is based on genetic programming, a robust tool, able to ensure the simultaneous selection of model structure and parameters. The assessment of potential solutions is done via a multiobjective approach, making use of both accuracy and parsimony criteria, in order to encourage the selection of accurate and compact models, characterized by expected good generalization capabilities. The evolutionary process is implemented from an elitist standpoint, and upgraded by means of two original contributions, namely an adaptive niching mechanism and an elite clustering procedure. The authors have also suggested a set of enhancements to aid the genetic operators in effectively exploring the space of possible model structures. In symbiosis with the customized genetic operators, a QR local optimization procedure was integrated within the algorithm. It exploits the nonlinear, linear in parameter form that the working models are generated in, for providing a faster parameter computation. The performances of the proposed methodology were revealed on two applications, of different complexity levels: the identification of a simulated nonlinear system and the identification of an industrial plant. Sat, 27 Feb 2010 00:00:00 +0200 http://dx.doi.org/10.4316/aece.2010.01018 http://dx.doi.org/10.4316/aece.2010.01018 N. D., TRIP, S., LUNGU, V., POPESCU, This paper presents a modelling method useful in the education process for the study of DC-DC power conversion principles using pulse width modulation converters. In this paper, the proposed modelling method is applied to a switched mode Fly-back supply. The model of the supply circuit includes the main parasitic elements of its component parts. To analyze the operation mode of the switched mode Fly-back supply its model is implemented with the help of MATLAB programming environment. The implementation of the model is used to simulate the behaviour of the Fly-back supply for both continuous conduction and discontinuous conduction modes, in transient and steady state conditions. The model and its implementation offer to the users an easier way to understand and analyze the operation principle of the switched mode power supplies. Moreover, the authors developed a graphic user interface dedicated to this study. The paper includes simulation and experimental results that validate the model of the supply. Sat, 27 Feb 2010 00:00:00 +0200 http://dx.doi.org/10.4316/aece.2010.01019 http://dx.doi.org/10.4316/aece.2010.01019 G. A., LAZAR, N. R., BUZATU, E., COJOCARIU, L., TRIFINA, Turbo codes are a parallel concatenation of two or more convolutional codes, separated by interleavers, therefore their performance is not influenced just by the constituent encoders, but also by the interleaver. For short frame turbo codes, the selection of a proper interleaver becomes critical. This paper presents a new algorithm of obtaining a code matched interleaver leading to a very high minimum distance and improved performance. Sat, 27 Feb 2010 00:00:00 +0200 http://dx.doi.org/10.4316/aece.2010.01020 http://dx.doi.org/10.4316/aece.2010.01020 G., BUTA, E., COCA, A., GRAUR, Wireless Sensor Networks (WSN) are challenging and efficient in a large field of applications like object location or distance determination between sensor nodes. In this paper are presented some considerations concerning the method of distance estimation between WSN nodes using the RF power level received by one sensor node. The experimental determinations were made using a WSN system composed of ten wireless modules (one coordinator module and nine WSN nodes). The RF power level received by a sensor node was measured at variable distances, and the dBm values recorded were then used in the distance determination formula. The tests were made in a 3 meters semi-anechoic chamber - in order the results not to be affected by other radio frequency emissions from the surrounding environment - using a 20 Hz - 26.5 GHz EMI Test Receiver, a log-periodic antenna and RF cables. Sat, 27 Feb 2010 00:00:00 +0200 http://dx.doi.org/10.4316/aece.2010.01021 http://dx.doi.org/10.4316/aece.2010.01021 I., BIROU, V., MAIER, S., PAVEL, C., RUSU, The aim of this paper is to present a new speed control structure for induction motors (IM) by using fuzzy-logic based speed controllers. A fuzzy controller is designed to achieve fast dynamic response and robustness for low and high speeds. Different types of membership functions of the linguistic variables and output/input characteristics are analyzed. A simple but robust structure enables a wide range speed control of the driving system. The rotor flux field oriented control (FOC) is realized by using a flux observer based on the IM model with nonlinear parameters. The control is extended to operate also in the field weakening region with an optimal rotor flux regulation. The control structure was implemented on a computer system, based on a fixed point digital signal processor (DSP). To verify the performances of the proposed driving system, simulated and experimental results are presented. Sat, 27 Feb 2010 00:00:00 +0200 http://dx.doi.org/10.4316/aece.2010.01022 http://dx.doi.org/10.4316/aece.2010.01022 G., BACHIR, A., BENDIABDELLAH, Two different control strategies applied to a direct AC-AC six phase matrix converter are investigated in the present paper. The first strategy is derived from the Venturini method and the second approach is practically an extension of the scalar strategy control. Both strategies were originally applied to the three phase matrix converter. The current investigation deals with a comparative performance study of a double star induction motor fed from a six-phase matrix converter using the two above modified control strategies. After a theoretical introduction of the six-phase matrix converter, a detailed description of the strategies implementation is presented followed by a discussion of results obtained simulation results. Sat, 27 Feb 2010 00:00:00 +0200 http://dx.doi.org/10.4316/aece.2010.01023 http://dx.doi.org/10.4316/aece.2010.01023 Z., HUANG, Y., FANG, X., XIE, M., PAN, No abstract available. Sat, 27 Feb 2010 00:00:00 +0200 http://dx.doi.org/10.4316/aece.2010.02001 http://dx.doi.org/10.4316/aece.2010.02001 A., STEIMEL, After de-regulation of the former state-owned railways and severe restructuring of the railway industry in the last 15 years, more innovative vehicle concepts saw the light of the day. Power electronics, already formerly being a pacemaker for progress of traction vehicles, brought forth an utmost standardization of the main drive by means of the IGBT-converter-fed induction motor drive. This is independent of the railway supply voltage system or of a diesel prime mover, for locomotives, high-speed and mass-transit trains as well as for tramways. Vehicles able to operate on all four European railway voltage systems have become feasible and are used now widely. New trends as Permanent-Magnet Synchronous Motors or Medium-Frequency Transformers are discussed, and a short overlook over actual field-oriented high-performance motor control systems - including a speed-sensorless variant - is given. Power electronics dominates the field of conversion of the 16.7-Hz railway supply power, typical for Central Europe, from the 50-Hz three-phase utility grid. Mon, 31 May 2010 00:00:00 +0300 http://dx.doi.org/10.4316/aece.2010.02002 http://dx.doi.org/10.4316/aece.2010.02002 Y., ONER, N., BEKIROGLU, S., OZCIRA, Permanent magnet DC motor-generators (PMDC, PMSG) have been widely used in industrial and energy sectors recently. Power control of these systems can be achieved by controlling the output voltage. In this study, PMDC-PMSG systems are mathematically modeled and simulated in MATLAB and Simulink software. Then the results are discussed. A low power permanent magnet synchronous generator is driven by a permanent magnet DC motor and the output voltage is controlled by a frequency cycle-converter. The output of a half-wave uncontrolled rectifier is applied to an SPWM inverter and the power is supplied to a 300V, 50Hz load. The load which is connected to an LC filter is modeled by state-space equations. LC filter is utilized in order to suppress the voltage oscillations at the inverter output. Mon, 31 May 2010 00:00:00 +0300 http://dx.doi.org/10.4316/aece.2010.02003 http://dx.doi.org/10.4316/aece.2010.02003 A. D., IOAN, This work presents a less known theoretical method for the synthesis of complex hardware automata by using the transition matrix, together with a new practical method for visual implementation inside FPGA circuits, with library schematic symbols from the Altium Designer software environment. Because these techniques need to be presented by example, the classical shift and add unsigned multiply algorithm was chosen for review. Obviously, this is not the most efficient algorithm, but it serves the declared purpose and it can still be used in a real system when the hardware must be minimal. Furthermore, an essential correction to the optimal version of this algorithm was made. The techniques are exemplified by doing an original implementation: starting from the initial organigram, passing through transition matrix synthesis stage and reaching to the final fully functional system on a Digilent Spartan-3 FPGA development board, which includes the user interface too. Mon, 31 May 2010 00:00:00 +0300 http://dx.doi.org/10.4316/aece.2010.02004 http://dx.doi.org/10.4316/aece.2010.02004 C., NEMES, F., MUNTEANU, The objective of the present paper is to estimate the electric power distribution of a wind farm using the output power distribution and the probability of simultaneously running of wind turbines. In this paper, a methodology for the electric power distribution of a wind turbine, using the characteristic output power-wind and the Weibull distribution of wind speed was given first. The methodology was applied to a region from north-east of Romania, and finally, the analytic distributions were compared to Monte-Carlo simulation. Mon, 31 May 2010 00:00:00 +0300 http://dx.doi.org/10.4316/aece.2010.02005 http://dx.doi.org/10.4316/aece.2010.02005 C., SULIMAN, C., CRUCERU, F., MOLDOVEANU, In this paper we have developed a Matlab/Simulink based model for monitoring a contact in a video surveillance sequence. For the segmentation process and corect identification of a contact in a surveillance video, we have used the Horn-Schunk optical flow algorithm. The position and the behavior of the correctly detected contact were monitored with the help of the traditional Kalman filter. After that we have compared the results obtained from the optical flow method with the ones obtained from the Kalman filter, and we show the correct functionality of the Kalman filter based tracking. The tests were performed using video data taken with the help of a fix camera. The tested algorithm has shown promising results. Mon, 31 May 2010 00:00:00 +0300 http://dx.doi.org/10.4316/aece.2010.02006 http://dx.doi.org/10.4316/aece.2010.02006 A. E., SANTO, M. R., CALADO, C., CABRITA, The linear counterpart of the rotational switched reluctance drive is receiving increasing attention from academic and industrial societies. The special characteristics of this driving technology, that normally works in a highly magnetic saturation regimen, make the development of efficient design methodologies more difficult. This paper proposes a new numerical model of a Linear Switched Reluctance Actuator based on the flux tube method. For validation purposes, simulation results obtained from the application of presented model are compared with the ones obtained from the application of a commercial finite element tool. The modulation technique proposed here makes possible, with minimal computational effort, the evaluation of the impact in actuator behaviour caused by the changes on the magnetic circuit geometries. Mon, 31 May 2010 00:00:00 +0300 http://dx.doi.org/10.4316/aece.2010.02007 http://dx.doi.org/10.4316/aece.2010.02007 M., VINTAN, A phase-to-ground fault occurring on a transmission line divides the line into two sections, each extending from the fault towards one end of the line. These two sections of the line may be considered infinite if some certain conditions are met; otherwise, they must be regarded as finite. This paper treats the case when those two sections of the line are both very long and allows the determination of the ground fault current distribution in power networks. The influence of the coupling factor between the faulted phase and the ground wire on the ground fault current distribution is studied. Mon, 31 May 2010 00:00:00 +0300 http://dx.doi.org/10.4316/aece.2010.02008 http://dx.doi.org/10.4316/aece.2010.02008 S. G., PENTIUC, I., TOBOLCEA, O. A., SCHIPOR, M., DANUBIANU, D. M., SCHIPOR, This interdisciplinary research was developed with a view to create and implement an intelligent informatics system for the treatment of dyslalic disorders, specific to the Romanian language (CBTS system - computer-based speech therapy), as a complementary speech therapy method, customised and client-oriented. The rules of the logotherapeutic guide have been expressed in pseudocode programs in order to allow a greater flexibility in expressing the logotherapeutic procedures in an informatics system. The pseudocode logopedic programs comprise the succession of stages of the therapeutic program from a speech therapy perspective, and based on what the expert system can achieve. The LOGOMON system is conceived in order to assist the physical therapist and the child during the entire therapeutic period, recording the main data related to the child, which proved to be useful in diagnosis and treatment. The experimental validation of the system proved that assisted therapy contributes to the improvement of classical therapy, to obtaining optimal results in correcting the dyslalic person's speech. Mon, 31 May 2010 00:00:00 +0300 http://dx.doi.org/10.4316/aece.2010.02009 http://dx.doi.org/10.4316/aece.2010.02009 G., ANTONESEI, C., TURCU, A., GRAUR, One of most common and difficult challenge when creating a single SoC with digital (sub)sections is caused by the various master clock (MCLK) frequencies that each individual IC had originally. There are several methods to solve this, but when constraint by price and power consumption, the design engineers must find the optimum one. The sample rate converters (SRC) are an example of solution that can simplify the architecture in some of these cases. However, even for the SRCs themselves, we need to come up with novel and efficient architectures. This paper presents such an example from mobile phones chips on how to successfully mix on the same silicon, an audio sigma-delta DAC which should support all the standard audio rates using a 13MHz MCLK frequency imposed by the RF section incorporated inside the same chip. The document will go from showing the top-level digital signal processing down to the actual hardware implementation. Mon, 31 May 2010 00:00:00 +0300 http://dx.doi.org/10.4316/aece.2010.02010 http://dx.doi.org/10.4316/aece.2010.02010 G., GRIGORAS, G., CARTINA, E. C., BOBRIC, The power/energy losses reduction in distribution systems is an important issue during planning and operation, with important technical and economical implications. Thus, the energy losses minimization implies not only the technical improvement of the network, through its renewal with the introduction of the technological innovations in the equipment and circuit components as well as the optimal planning of the design and development of the network, but also requires the use of the methods and software tools to facilitate the operation process. The paper presents a strategy for power/energy saving which replacement of the 6 kV voltage level with 20 kV voltage level in correlation with the extent of using efficient transformers. In this line, different urban distribution networks were analyzed using fuzzy techniques. Mon, 31 May 2010 00:00:00 +0300 http://dx.doi.org/10.4316/aece.2010.02011 http://dx.doi.org/10.4316/aece.2010.02011 A., Van NIEUWENHUYSE, J., WYFFELS, J.-P., GOEMAERE, L., De STRYCKER, B., NAUWELAERS, This paper introduces the technology Time of Arrival (TOA) based on chirp pulses (according to IEEE 802.15.4a) as a means to perform localization in Wireless Sensor Networks (WSN's) active at 2.4 GHz. Advantages and disadvantages of the technology are discussed and act as a guideline for improving localization accuracy. Tests concerning TOA are performed by means of the location engine of Nanotron. Adapting this engine leads to improved localization results. It is shown that TOA measurements are susceptible to reflections and dynamic environments. Mon, 31 May 2010 00:00:00 +0300 http://dx.doi.org/10.4316/aece.2010.02012 http://dx.doi.org/10.4316/aece.2010.02012 A., SIMION, L., LIVADARU, S., MIHAI, A., MUNTEANU, C. G., CANTEMIR, The paper presents a study concerning the performance developed by induction motors destined for motorization of heavy electric vehicles such as trucks. Taking into consideration the imposed restrictions, one presents, in a comparative manner, the main geometrical parameters which come of the classical design algorithms. A special attention is dedicated to the winding design, since it has to ensure two synchronous speeds corresponding to 16 and 8 poles, respectively. Moreover, the influence of the rotor slots shape for the improvement of the start-up is analyzed. Finally, a FEM-based study (approach based on finite element method) is performed to put in view specific torque and slip values such as rated, start-up and pull-out ones. Mon, 31 May 2010 00:00:00 +0300 http://dx.doi.org/10.4316/aece.2010.02013 http://dx.doi.org/10.4316/aece.2010.02013 A., REZAZADEH, The application of Genetic Optimization Algorithm in estimation of the parameters of servo electrical drives is proposed. In comparison with this planned method, least squared error (LSE) estimation method is considered as an expedient method for parameter estimation. Regardless of LSE estimation, Genetic Algorithm method is not restricted to the linear systems with respect to the parameters. GA is imported as an optimization method in comparison with conventional optimization methods because of its power in searching whole solution space with more probability to finding the global optimum. As a condition for convergence, transient excitation is considered instead of persistent excitation. Finally, comparison between LSE and GA based parameter estimation is presented to indicate robustness and resolution of GA identification method. It will be shown that the GA method of estimation has better results in the startup and transients of the system where there is a lack of persistent excitation. Mon, 31 May 2010 00:00:00 +0300 http://dx.doi.org/10.4316/aece.2010.02014 http://dx.doi.org/10.4316/aece.2010.02014 N. L., TUDOR, This article proposes a cache pattern with multi-queries and describes the multi-query optimization with scheduling, caching and pipelining. A set of cache patterns is derived from a set of class of multi-queries that are loaded into the cache. Each cache pattern represents a unique equivalence class in the set of patterns. The multi-query optimization with scheduling, caching and pipelining provides efficient heuristics, for a good queries ordering using a single invocation on the entire batch of queries. Multi-query optimization chooses the results of sub-expression that should be admitted to or discarded from cache, when it executes queries. We introduce the heuristic of pair queries and define the equivalence class of multi-queries from cache pattern. We show that the union of all equivalence classes of queries from the cache patterns is the set of cache patterns. Mon, 31 May 2010 00:00:00 +0300 http://dx.doi.org/10.4316/aece.2010.02015 http://dx.doi.org/10.4316/aece.2010.02015 O., BRUDARU, D., POPOVICI, C., COPACEANU, This paper presents a new approach with cellular multigrid genetic algorithms for the I-shaped and U-shaped assembly line balancing problems, including parallel workstations and compatibility constraints. First, a cellular hybrid genetic algorithm that uses a single grid is described. Appropriate operators for mutation, hypermutation, and crossover and two devoration techniques are proposed for creating and maintaining groups based on similarity. This monogrid algorithm is extended for handling many populations placed on different grids. In the multigrid version, the population of each grid is organized in clusters using the positional information of the chromosomes. A similarity preserving communication protocol between the clusters placed on different grids is introduced. The experimental evaluation shows that the multigrid cellular genetic algorithm with communicating grids is better than the hybrid genetic algorithm used for building it, whereas it dominates the monogrid version in all cases. Absolute performance is evaluated using classical benchmarks. The role of certain components of the cellular algorithm is explained and the effect of some parameters is evaluated. Mon, 31 May 2010 00:00:00 +0300 http://dx.doi.org/10.4316/aece.2010.02016 http://dx.doi.org/10.4316/aece.2010.02016 S., MOTOASCA, G., SCUTARU, The paper deals with an analytical model for hysteresis cycle representation. The hysteresis curve is decomposed in a series of arcs of circles and segments of lines. Each arc of circle or segment of line is expressed using analytical geometry as a function of some given parameters or calculated ones. The easiness of the model proposed is given by the small amount of input data needed to represent the hysteresis cycle in a satisfactory way. Using an inverse mapping function from major hysteresis branches the minor cycles, reversal curve of the first kind or curve of first magnetization can be obtained. Finally a comparison between the measured data and modelled ones was made. Mon, 31 May 2010 00:00:00 +0300 http://dx.doi.org/10.4316/aece.2010.02017 http://dx.doi.org/10.4316/aece.2010.02017 M., CERLINCA, C., TURCU, T., CERLINCA, R., PRODAN, This paper introduces a new client-server messaging engine used to exchange clinical data between various medical software applications. Our portal uses the HL7 (Health Level Seven) messaging standard to provide translated clinical data to HL7 and non-HL7 client applications. We used HL7 because this standard is worldwide used to facilitate the communication between clinical applications. Mon, 31 May 2010 00:00:00 +0300 http://dx.doi.org/10.4316/aece.2010.02018 http://dx.doi.org/10.4316/aece.2010.02018 G., LIVINT, V., HORGA, D., STICEA, M., RATOI, M., ALBU, In this paper an experimental model with a distributed control system of a hybrid electrical vehicle is presented. A communication CAN network of high speed (1 Mbps) assures a distributed control of the all components. The modeling and the control of different operating regimes are realized on an experimental test-bench of a hybrid electrical vehicle. The experimental results concerning the variations of the mains variables (currents, torques, speeds) are presented. Mon, 31 May 2010 00:00:00 +0300 http://dx.doi.org/10.4316/aece.2010.02019 http://dx.doi.org/10.4316/aece.2010.02019 F., SANDU, S., CSEREY, E., MILE-CIOBANU, This article aims to present a simulation and emulation software that was developed to simulate the call flows of a LTE (Long Term Evolution) network. LTE is the latest Mobile Telecommunications technology being currently in development and testing phase. The simulator can be used as an e-Learning software, for teaching the procedures and phases of different LTE scenarios. Call flows can be visualized trough the simulation panel, where signaling messages can be run continuously or step-by-step, for the purpose of detailed analysis. The simulator has the capability to generate real signaling packets, that are being sent to a virtual loopback adapter and captured / dissected using the Wireshark software. In this way a whole simulation environment is created that is very useful for teaching the latest mobile telecommunications technology, the LTE (Long Term Evolution) system. Mon, 31 May 2010 00:00:00 +0300 http://dx.doi.org/10.4316/aece.2010.02020 http://dx.doi.org/10.4316/aece.2010.02020 I. A., LETIA, A., GROZA, This research presents an argumentation based decision support system for implementing the Hazard Analysis at Critical Control Points (HACCP) standard in food industry. Our analysis starts by identifying the adequate technical instrumentation needed for supporting different aspects of the HAACP system. An integrated architectural solution is presented. The framework is built around concept maps and it exploits the integration of ontologies with argumentation theory by using the Argument Interchange Format ontology. Mon, 31 May 2010 00:00:00 +0300 http://dx.doi.org/10.4316/aece.2010.02021 http://dx.doi.org/10.4316/aece.2010.02021 N. C., GAITAN, V. G., GAITAN, S. G., PENTIUC, I., UNGUREAN, E., DODIU, Infrastructure underlying the distributed information systems is heterogeneous and very complex. Middleware allows the development of distributed information systems, without knowing the functioning details of an infrastructure, by its abstracting. An essential issue on designing such systems is represented by choosing the middleware technologies. An architectural model of a SCADA system based on middleware is proposed in this paper. This system is formed of servers that centralize data and clients, which receive information from a server, thus allowing the chart displaying of such information. All these components own a specific functionality and can exchange information, by means of a middleware bus. A middleware bus signifies a software bus, where more middleware technologies can coexist. Mon, 31 May 2010 00:00:00 +0300 http://dx.doi.org/10.4316/aece.2010.02022 http://dx.doi.org/10.4316/aece.2010.02022 G. A., LAZAR, N. R., BUZATU, E., COJOCARIU, L., TRIFINA, R., VIERU, Turbo codes offer extraordinary performance, especially at low signal to noise ratios, due to a low multiplicity of low weight code words. The interleaver design is critical in order to realize an apparent randomness of the code, thus further enhancing its performance, especially for short block frames. This paper presents four new deterministic interleaver design methods, that lead to highly performing turbo coding systems, namely the block-spread, the block-backtracking and their variations the linearly-spread and linearly-backtracking interleavers. The design methods are explained in depth and the results are compared against some of the most wide-spread turbo code interleavers. Furthermore, the selection method of the generator polynomials used in the simulations is explained. Mon, 31 May 2010 00:00:00 +0300 http://dx.doi.org/10.4316/aece.2010.02023 http://dx.doi.org/10.4316/aece.2010.02023 L., FRANGU, M., MAZAREL, C., CHICULITA, In this paper, a problem of audio source localization is solved, using a network of embedded devices. The intensive computing procedures (such as the crosscorrelation functions) are performed by the embedded devices, which have enough speed and memory for this task. A central computer computes the position in a fast procedure, using the data transmitted by the network nodes, and plays the role of operator interface. The paper also contains the description of the embedded devices, which are designed and manufactured by the authors. They prove to be suited for this kind of application, as they perform fast computation and require low power and small space for installing. Mon, 31 May 2010 00:00:00 +0300 http://dx.doi.org/10.4316/aece.2010.02024 http://dx.doi.org/10.4316/aece.2010.02024 S., MANJUNATHA, K. V., PANDURANGA, The recent trends in electrical power distribution system operation and management are aimed at improving system conditions in order to render good service to the customer. The reforms in distribution sector have given major scope for employment of distributed generation (DG) resources which will boost the system performance. This paper proposes a heuristic technique for allocation of distribution generation source in a distribution system. The allocation is determined based on overall improvement in network performance parameters like reduction in system losses, improvement in voltage stability, improvement in voltage profile. The proposed Network Performance Enhancement Index (NPEI) along with the heuristic rules facilitate determination of feasible location and corresponding capacity of DG source. A Priority list is prepared with decreasing values of NPEI so that the designer can select most feasible location. The developed approach is tested with different test systems to ascertain its effectiveness. Mon, 31 May 2010 00:00:00 +0300 http://dx.doi.org/10.4316/aece.2010.02025 http://dx.doi.org/10.4316/aece.2010.02025 L., MIHET-POPA, V., GROZA, The installation of wind turbines in power systems has developed rapidly through the last 20 years. In this paper a complete simulation model of a 6 x 2 MW wind turbines is presented using data from a wind farm installed in Denmark. A model of the wind turbine with cage-rotor induction generator is presented in details. A set of simulations are performed and they show that it is possible to simulate a complete wind farm from wind to the grid. The simulation tool can also be used to simulate bigger wind farms connected to the grid. Mon, 31 May 2010 00:00:00 +0300 http://dx.doi.org/10.4316/aece.2010.02026 http://dx.doi.org/10.4316/aece.2010.02026 L., VLADAREANU, G., TONT, I., ION, M. S., MUNTEANU, D., MITROI, The paper presents ZPM dynamic control of walking robots, developing an open architecture real time control multiprocessor system, in view of obtaining new capabilities for walking robots. The complexity of the movement mechanism of a walking robot was taken into account, being a repetitive tilting process with numerous instable movements and which can lead to its turnover on an uneven terrain. The control system architecture for the dynamic robot walking is presented in correlation with the control strategy which contains three main real time control loops: balance robot control using sensorial feedback, walking diagram control with periodic changes depending on the sensorial information during each walk cycle, predictable movement control based on a quick decision from the previous experimental data. The results obtained through simulation and experiments show an increase in mobility, stability in real conditions and obtaining of high performances related to the possibility of moving walking robots on terrains with a configuration as close as possible to real situations, respectively developing new technological capabilities of the walking robot control systems for slope movement and walking by overtaking or going around obstacles. Mon, 31 May 2010 00:00:00 +0300 http://dx.doi.org/10.4316/aece.2010.02027 http://dx.doi.org/10.4316/aece.2010.02027 M., SEDIGHIZADEH, A., REZAZADEH, Nonlinear characteristics of wind turbines and electric generators necessitate complicated and nonlinear control of grid connected Wind Energy Conversion Systems (WECS). This paper proposes a modified self-tuning PID control strategy, using reinforcement learning for WECS control. The controller employs Actor-Critic learning in order to tune PID parameters adaptively. These Actor-Critic learning is a special kind of reinforcement learning that uses a single wavelet neural network to approximate the policy function of the Actor and the value function of the Critic simultaneously. These controllers are used to control a typical WECS in noiseless and noisy condition and results are compared with an adaptive Radial Basis Function (RBF) PID control based on reinforcement learning and conventional PID control. Practical emulated results prove the capability and the robustness of the suggested controller versus the other PID controllers to control of the WECS. The ability of presented controller is tested by experimental setup. Mon, 31 May 2010 00:00:00 +0300 http://dx.doi.org/10.4316/aece.2010.03001 http://dx.doi.org/10.4316/aece.2010.03001 Z., HUANG, Y., FANG, B., CHEN, M., PAN, The emergence of Internet has greatly revolutionized the way that geospatial information is collected, managed, processed and integrated. There are several important research issues to be addressed for distributed geospatial applications. First, the performance of geospatial applications is needed to be considered in the Internet environment. In this regard, the Grid as an effective distributed computing paradigm is a good choice. The Grid uses a series of middleware to interconnect and merge various distributed resources into a super-computer with capability of high performance computation. Secondly, it is necessary to ensure the secure use of independent geospatial applications in the Internet environment. The Grid just provides the utility of secure access to distributed geospatial resources. Additionally, it makes good sense to overcome the heterogeneity between individual geospatial information systems in Internet. The Open Geospatial Consortium (OGC) proposes a number of generalized geospatial standards e.g. OGC Web Services (OWS) to achieve interoperable access to geospatial applications. The OWS solution is feasible and widely adopted by both the academic community and the industry community. Therefore, we propose an integrated framework by incorporating OWS standards into Grids. Upon the framework distributed geospatial queries can be performed in an interoperable, high-performance and secure Grid environment. Tue, 31 Aug 2010 00:00:00 +0300 http://dx.doi.org/10.4316/aece.2010.03002 http://dx.doi.org/10.4316/aece.2010.03002 S., POSTALCIOGLU OZGEN, This paper includes a Heading Control (HC) system for a multi-body vehicle. HC system helps reducing the required torque from the driver and improves the lane keeping efficiency. HC system is important for safety and driver comfort in traffic. The controller performance is examined on a virtual test drive platform. The optimal control theory is applied to HC system and examined on a curved path and under a side wind disturbance. Different assistance levels are applied to see the characteristics of the controller with different virtual test drivers. The results are analyzed based on three performance indices; lane keeping performance (LKP) index, assist torque performance (ATP) index and driver torque performance (DTP) index. As seen from the results while using HC system the lateral displacement decreases as the lane keeping performance increases and the driver torque performance decreases as the assist torque performance increases. Tue, 31 Aug 2010 00:00:00 +0300 http://dx.doi.org/10.4316/aece.2010.03003 http://dx.doi.org/10.4316/aece.2010.03003 N., GHAFFARZADEH, B., VAHIDI, This paper proposed a novel technique to effectively discriminate between the HIF and the normal system operation events in distribution by combining a preprocessing module based on wavelet packet transform with an artificial neural network(ANN). Wavelet packet is firstly applied to extract of distinctive feature of current signals. Then this information is introduced to training ANN for identifying an HIF from the normal system operation events. The simulated results clearly show that the proposed technique can accurately identify the HIF in overhead distribution feeder. Tue, 31 Aug 2010 00:00:00 +0300 http://dx.doi.org/10.4316/aece.2010.03004 http://dx.doi.org/10.4316/aece.2010.03004 M. V., MICEA, A., STANCOVICI, D., CHICIUDEAN, C., FILOTE, This paper focuses on the problem of autonomous distance calculation between multiple mobile robots in collaborative systems. We propose and discuss two distinct methods, specifically developed under important design and functional constraints, such as the speed of operation, accuracy, energy and cost efficiency. Moreover, the methods are designed to be applied to indoor robotic systems and are independent of fixed landmarks. The measurement results, performed on the CORE-TX case study, show that the proposed solutions meet the design requirements previously specified. Tue, 31 Aug 2010 00:00:00 +0300 http://dx.doi.org/10.4316/aece.2010.03005 http://dx.doi.org/10.4316/aece.2010.03005 S. I., DEACONU, M., TOPOR, G. N., POPA, D., BISTRIAN, This paper investigates the influence of the parameters of the machine and of the soft starter on the dynamics of the induction machine start. In order to evaluate the effects of this variation we have used a design of experiments (DOE). The situations may reproduce actual situations occurred in practice, for example the variation of initial voltage Ui , modification of the start time and load value. In the present paper we have investigated the relation between the inrush current, voltage dip at the startup of one industrial soft starter. Using an already predefined fire angle characteristic the influence of the initial voltage was also evaluated. Tue, 31 Aug 2010 00:00:00 +0300 http://dx.doi.org/10.4316/aece.2010.03006 http://dx.doi.org/10.4316/aece.2010.03006 T., SENGULER, E., KARATOPRAK, S., SEKER, In this study, it is aimed to track the aging trend of the incipient bearing damage in an induction motor which is subjected to an accelerated aging process. For this purpose, a new Multilayer perceptron (MLP) neural network approach is introduced. The input signals are extracted from power spectral densities (PSD) of the vibration signals taken from a 5-HP induction motor. Principal component analysis (PCA) has been applied to select the best possible feature vectors as a dimensionality reduction purpose. Variance and entropy values are used as the targets of the MLP network. The healthy motor condition was modelled by the MLP network considering all load conditions. The results showed that the incipient bearing damage was clearly extracted by the oscillations of the MLP output error. Tue, 31 Aug 2010 00:00:00 +0300 http://dx.doi.org/10.4316/aece.2010.03007 http://dx.doi.org/10.4316/aece.2010.03007 D., PETREUS, D., MOGA, A., RUSU, T., PATARAU, M., MUNTEANU, A photovoltaic (PV) system, based on a Maximum Power Point Tracking (MPPT) controller that extracts the maximum possible output power from the solar panel is described. Output efficiency of a PV energy system can be achieved only if the system working point is brought near the maximum power point (MPP). The proposed system, making use of several MPPT control algorithms (Perturb and Observe, Incremental conductance, Fuzzy Logic), demonstrates in simulations as well as in real experiments good tracking of the optimal working point. Tue, 31 Aug 2010 00:00:00 +0300 http://dx.doi.org/10.4316/aece.2010.03008 http://dx.doi.org/10.4316/aece.2010.03008 A., KOOCHAKI, S. M., KOUHSARI, This paper presents a novel method for modeling internal faults in a power transformer. This method uses a distributed computing approach for analysis of internal fault in transient stability (T/S) studies of electrical networks using Diakoptics and large change sensitivity (LCS) concepts. The combination of these concepts by phase frame model of transformer will be used here to develop an internal fault simulation of transformers. This approach leads to a model which is compatible with commercial phasor-based software packages. Consequently, it enables calculation of fault currents in any branch of the network due to a winding fault of a power transformer. The proposed method is implemented successfully and validated by time domain software and GEC group measurement results. Tue, 31 Aug 2010 00:00:00 +0300 http://dx.doi.org/10.4316/aece.2010.03009 http://dx.doi.org/10.4316/aece.2010.03009 A., BITOLEANU, M., POPESCU, D., MARIN, M., DOBRICEANU, This paper is focused on finding the parameters of a second order interface filter connected between the power system and the shunt active filter based on switching frequency of the active filter. Many publications on power active filters include various design methods for the interface inductive filter which take into account the injected current and its dynamic. Compared to these ones, the approach presented in this paper is oriented toward the design of the interface filter starting from filter transfer functions by imposing the performances of the filter. Tue, 31 Aug 2010 00:00:00 +0300 http://dx.doi.org/10.4316/aece.2010.03010 http://dx.doi.org/10.4316/aece.2010.03010 K., HARTANI, Y., MILOUD, This paper proposes the space vector pulse width modulation (SVPWM) control scheme for three-phase voltage source PWM rectifier. The control system based on SVPWM includes two PI controllers which are used to regulate the AC currents and DC-link voltage. The proposed control can stabilize the minimum of the systems storage function at the desired equilibrium point determined by unity power factor and sinusoidal current on the AC side, and constant output voltage on the DC side. So the stable state performance and robustness against the load's disturbance of PWM rectifiers are both improved. The simulation result shows feasibility of this strategy. Tue, 31 Aug 2010 00:00:00 +0300 http://dx.doi.org/10.4316/aece.2010.03011 http://dx.doi.org/10.4316/aece.2010.03011 N. R., BUZATU, A., LAZAR, D., ALEXA, G. A., LAZAR, M., MOISA, The paper presents the design and analysis of a three-phase static converter, composed of a Rectifier with Near Sinusoidal Input Currents (RNSIC), which ensures the DC bus voltage level for a three phase Incomplete Bridge Inverter (IBI), used to drive an asynchronous motor. The proposed circuit has a low input current harmonic content, can ensure the load overcurrent protection and has a better reliability. The converter can be designed to provide any required output maximum power under a desired DC link bus voltage. Tue, 31 Aug 2010 00:00:00 +0300 http://dx.doi.org/10.4316/aece.2010.03012 http://dx.doi.org/10.4316/aece.2010.03012 H., RADMANESH, M., ROSTAMI, Ferroresonance or nonlinear resonance is a complex electrical phenomenon, which may cause over voltages and over currents in the electrical power system which endangers the system reliability and continuous safe operating. This paper studies the effect of circuit breaker shunt resistance on the control of chaotic ferroresonance in a voltage transformer. It is expected that this resistance generally can cause ferroresonance dropout. For confirmation this aspect Simulation has been done on a one phase voltage transformer rated 100VA, 275kV. The magnetization characteristic of the transformer is modeled by a single-value two-term polynomial with q=7. The simulation results reveal that considering the shunt resistance on the circuit breaker, exhibits a great mitigating effect on ferroresonance over voltages. Significant effect on the onset of chaos, the range of parameter values that may lead to chaos along with ferroresonance voltages has been obtained and presented. Tue, 31 Aug 2010 00:00:00 +0300 http://dx.doi.org/10.4316/aece.2010.03013 http://dx.doi.org/10.4316/aece.2010.03013 N., BEKIROGLU, S., OZCIRA, In this study, direct torque control (DTC) of a permanent magnet synchronous motor is realized with a sensorless speed control technique without using an observer. Space vector pulse width modulation (SVPWM) technique is applied in order to determine the switching sequence of the voltage source inverter. Torque and flux, the main variables of the DTC, are estimated by using the mathematical model of the motor. Estimated torque and flux values are compared with their references in every control cycle. Then, according to the torque and flux demand, the voltage vector is constituted. In the proposed control scheme, speed is estimated by using flux calculations and a PI controller is used to process the torque and flux errors. Furthermore, a low-pass (LP) filter is implemented within the proposed system for voltage and current harmonics suppression. The results proved that proposed scheme for the DTC provides the speed control under various torque demands without employing a sensor. The proposed system performs very well for a sensorless operation and effectively eliminates the harmonics due to the LP filter. Tue, 31 Aug 2010 00:00:00 +0300 http://dx.doi.org/10.4316/aece.2010.03014 http://dx.doi.org/10.4316/aece.2010.03014 M., RAMAKRISHNAN, V. P., RANJAN, In this paper, Adaptive Power Control with Overhearing Avoidance (APC+OA) has been proposed. The proposed power control algorithm has been implemented in PICSENSE wireless sensor nodes. The energy consumption of proposed MAC has been compared with that of On Demand Transmission Power Control (ODTPC) protocol and it is shown that the Adaptive Power Control with Overhearing Avoidance gives higher energy conservation compared to ODTPC. The power level convergence towards the optimal power for APC-OA is two times faster than the ODTPC. Tue, 31 Aug 2010 00:00:00 +0300 http://dx.doi.org/10.4316/aece.2010.03015 http://dx.doi.org/10.4316/aece.2010.03015 R., MITRAN, P., BECHET, The present paper aims to determine the optimum parameters for the detection of downlink TETRA signals, through energy measurement. In order to optimize the detection parameters we have assessed the probabilities of detection and of false alarm, based on the estimated power distributions, measured by the Parzen method. The TETRA signals power has been measured with an experimental system, the data having been processed by MATLAB software. The obtained results could contribute to the improvement of TETRA mobile station algorithms with the aim of base stations broadcasting channels detection and to the improvement of the measurement system settings in order to obtain the coverage maps of the TETRA base stations. Tue, 31 Aug 2010 00:00:00 +0300 http://dx.doi.org/10.4316/aece.2010.03016 http://dx.doi.org/10.4316/aece.2010.03016 M., HAJIZADEH, M. S., HELFROUSH, M. J., DEHGHANI, A., TASHK, In this paper, an innovative blind watermarking algorithm has been proposed for imagery applications. This algorithm has used the coefficients of the discrete wavelet transform of the host image in the form of super trees to embed the predefined binary watermark in the host image. In this scheme, a pseudo random sequence is generated to determine the exact wavelet super trees used for embedding procedure. In the next step, after choosing the maximum and second maximum amplitude coefficients of each super tree, the distance vector between two coefficients is computed. For embedding bit zero of the specified watermark, the values of the distance vector elements are decreased, while for embedding bit 1, those values will be increased based on the proposed formulas. The experimental results show that the proposed algorithm has significant robustness against image processing attacks, especially JPEG compression and also the PSNR value for the watermarked images generated by the proposed method is more than 42 dB. Tue, 31 Aug 2010 00:00:00 +0300 http://dx.doi.org/10.4316/aece.2010.03017 http://dx.doi.org/10.4316/aece.2010.03017 Y., ZHANG, Z., WANG, J., ZHANG, J., MA, Electric power system is one of the most complex artificial systems in the world. The complexity is determined by its characteristics about constitution, configuration, operation, organization, etc. The fault in electric power system cannot be completely avoided. When electric power system operates from normal state to failure or abnormal, its electric quantities (current, voltage and angles, etc.) may change significantly. Our researches indicate that the variable with the biggest coefficient in principal component usually corresponds to the fault. Therefore, utilizing real-time measurements of phasor measurement unit, based on principal components analysis technology, we have extracted successfully the distinct features of fault component. Of course, because of the complexity of different types of faults in electric power system, there still exists enormous problems need a close and intensive study. Tue, 31 Aug 2010 00:00:00 +0300 http://dx.doi.org/10.4316/aece.2010.03018 http://dx.doi.org/10.4316/aece.2010.03018 H., TEDJINI, Y., MESLEM, M., RAHLI, B., BERBAOUI, This paper deals with a hybrid shunt active power filter applied on 500 kV HVDC, after a description of the causes and effects harmonic pollution which may damage equipments and interrupt electric power customers service; in this paper we present the deferent solutions of this problem among one has to study the two most recent types of filtering: passive and hybrid filter. The hybrid filter consists of active filter connected in shunt with passive filter. The hybrid shunt active filter proposed is based on three levels PWM inverter and characterized by detecting the harmonic current flowing into the passive filter and controlled by notch algorithm. This structure has been applied on a test HVDC power system, is presented as a technical solution makes it possible to eliminate the disadvantages from passive filtering, and also economic price of active filtering part. The simulation results justified the effectiveness of this type of filter face of the classic passive filter. Tue, 31 Aug 2010 00:00:00 +0300 http://dx.doi.org/10.4316/aece.2010.03019 http://dx.doi.org/10.4316/aece.2010.03019 M., SEDIGHIZADEH, A., REZAZADEH, N. I., ELKALASHY, This paper reviews the major contributions to the high impedance fault (HIF) detection field throughout a 48-year period, from 1960 up to 2008, from classic approaches to heuristic algorithms. After surveying around 225 papers in the field, the amount of existing works for each method is identified and classified. The paper concludes with comparative tables and graphs demonstrating the frequency of each high impedance fault detection methods, and so it can be used as a guideline for researchers in this field. Tue, 31 Aug 2010 00:00:00 +0300 http://dx.doi.org/10.4316/aece.2010.04001 http://dx.doi.org/10.4316/aece.2010.04001 N. M., SEKULOVIC, M. C., STEFANOVIC, D. L., DRACA, A. S., PANAJOTOVIC, D. M., STEFANOVIC, In this paper, the performance of dual selection combining (SC) receiver in communications systems with a Rician desired signal affected by multiple Nakagami-m cochannel interferences (CCIs) is studied. This investigation is important since such environment seems to be the most realistic in microcellular radio communications systems. The performance analysis includes the channel correlation effect since in practice diversity is usually applied in small terminals so antenna elements can not be placed sufficiently apart to achieve independent fading channels. With assumption that CCIs are mutually independent and identically distributed, analytical expressions for the probability density function (PDF) and cumulative distribution function (CDF) of dual SC output signal-to-interference ratio (SIR) are derived and used to investigate important system performance measures, such as the average bit error probability (ABEP), channel capacity and outage probability. The proposed mathematical analysis is complemented by various graphically presented numerical results to show the effects of various system's parameters. In addition, the impact of diversity to the microcellular system's performance is also explored. Tue, 30 Nov 2010 00:00:00 +0200 http://dx.doi.org/10.4316/aece.2010.04002 http://dx.doi.org/10.4316/aece.2010.04002 M. S., POBORONIUC, D. E., WOOD, R., RIENER, N. N., DONALDSON, A new control strategy that supports the sitting down phase in FES-assisted standing in paraplegia is proposed. It is an adaptation of a well established closed-loop On/Off controller that uses trajectories within the state space of knee angle and knee angular velocity, but defines a zone between the On and Off sub-spaces for gradual change in the stimulation levels. This new controller has been experimentally tested on two paraplegic patients and it is concluded that compared to the conventional On/Off controller it better controls the lowering of the person toward the seat, by reducing knee-end velocity and handle reaction forces. It has a certain degree of interaction with the user's voluntary effort. Keeping the system simple in respect to the required number of sensors, only the knee angle measurements are required as feedback signal making the strategy simple and, thus, particularly useful for daily standing exercises in home environments. Tue, 30 Nov 2010 00:00:00 +0200 http://dx.doi.org/10.4316/aece.2010.04003 http://dx.doi.org/10.4316/aece.2010.04003 P., BRANDSTETTER, P., CHLEBIS, P., PALACKY, Direct torque control is one of modern methods of A.C. machines control. The direct torque control methods with direct calculation of the vector voltage and vector pulse width modulator were developed and experimentally tested at the Department of Electronics. The paper describes the theoretical assumptions of developed control methods and differences from classical direct torque methods. In the paper, important quantities are shown which were measured on a real induction motor drive with digital signal processor control system. Tue, 30 Nov 2010 00:00:00 +0200 http://dx.doi.org/10.4316/aece.2010.04004 http://dx.doi.org/10.4316/aece.2010.04004 M., FIRA, L., GORAS, C., BARABASA, N., CLEJU, The paper presents a number of results regarding the construction of specific overcomplete dictionaries for ECG compressed sensing (CS). The dictionaries were built using normal and patological cardiac patterns extracted from 24 recordings of the MIT-BIH Arrhythmia Database. It has been shown that the compression results obtained using the CS concept based on specific dictionaries are better that those using the wavelet overcomplete dictionaries. Starting from the concept of sparse signal with respect to a given overcomplete dictionary the paper present several results regarding the possibility of simple pattern classification as well. Tue, 30 Nov 2010 00:00:00 +0200 http://dx.doi.org/10.4316/aece.2010.04005 http://dx.doi.org/10.4316/aece.2010.04005 I. M., CIURUS, M., DIMIAN, A., GRAUR, This paper presents the results of the analysis of Polaroid optocoupler mechanical-electrical sensor static characteristics. Our paper achieves analysis on distance adjustment Polaroid optocouplers of LED-photoresistor and LED-phototransistor types. These optocouplers analysis was performed in two distinct cases by using 0.2 mm and 0.7 mm thick Polaroid filters. At present, this Polaroid optocoupler mechanical-electrical sensor is only a prototype. Tue, 30 Nov 2010 00:00:00 +0200 http://dx.doi.org/10.4316/aece.2010.04006 http://dx.doi.org/10.4316/aece.2010.04006 S., NIKOLI, D., ANTIC, B., DANKOVIC, M., MILOJKOVIC, Z., JOVANOVIC, S., PERIC, In this paper, we present a method for designing orthogonal, Legendre type filters. Realization of these filters is very simple and they are very fast, robust and precise. They can be used for generating the sequence of Legendre orthogonal functions. We have also developed a new method for positioning an antenna system, based on these filters, where the filter is applied in detection of electromagnetic field gradient. Control algorithm is based on improved method of gradients. Proposed control algorithm has been verified on practically realized, experimental antenna system and compared with some others tracking control algorithms. Performed experiments have verified efficiency, speed and accuracy of the proposed control method. Tue, 30 Nov 2010 00:00:00 +0200 http://dx.doi.org/10.4316/aece.2010.04007 http://dx.doi.org/10.4316/aece.2010.04007 A., MOSALLANEJAD, A., SHOULAIE, In this paper the magnetic flux density of tubular linear reluctance motor (TLRM) in open type magnetic circuit is studied. Also, all magnetic flux density calculation methods in winding of tubular linear reluctance motor are described. The effect of structure parameters on magnetic flux density is also discussed. Electromagnetic finite-element analysis is used for simulation of magnetic field, and simulation results of the magnetic field analysis with DC voltage excitation are compared with results obtained from calculation methods. The comparison yields a good agreement. Tue, 30 Nov 2010 00:00:00 +0200 http://dx.doi.org/10.4316/aece.2010.04008 http://dx.doi.org/10.4316/aece.2010.04008 I., MOCANU, In many areas such as commerce, medical investigations, and others, large collections of digital images are being created. Search operations inside these collections of images are usually based on low-level features of objects contained in an image: color, shape, texture. Although such techniques of content-based image retrieval are useful, they are strongly limited by their inability to consider the meaning of images. Moreover, specifying a query in terms of low level features may not be very simple. Image annotation, in which images are associated with keywords describing their semantics, is a more effective way of image retrieval and queries can be naturally specified by the user. The paper presents a combined set of methods for image retrieval, in which both low level features and semantic properties are taken into account when retrieving images. First, it describes some methods for image representation and retrieval based on shape, and proposes a new such method, which overcomes some of the existing limitations. Then, it describes a new method for image semantic annotation based on a genetic algorithm, which is further improved from two points of view: the obtained solution value - using an anticipatory genetic algorithm, and the execution time - using a parallel genetic algorithm. Tue, 30 Nov 2010 00:00:00 +0200 http://dx.doi.org/10.4316/aece.2010.04009 http://dx.doi.org/10.4316/aece.2010.04009 D. M., SCHIPOR, S. G., PENTIUC, O. A., SCHIPOR, In this paper we highlight the relations between LOGOMON - a Computer Based Speech Therapy System and dyslalia's training steps. Dyslalia is a speech disorder that affects pronunciation of one or many sounds. This presentation of the system is completed by a research regarding end-user (i.e. teachers and parents) attitude about the speech assisted therapy in general and about LOGOMON System in particular. The results of this research allow the improvement of our CBST system because the obtained information can be a source of adaptability to different expectations of the beneficiaries. Tue, 30 Nov 2010 00:00:00 +0200 http://dx.doi.org/10.4316/aece.2010.04010 http://dx.doi.org/10.4316/aece.2010.04010 F., ARVIN, K., SAMSUDIN, A. R., RAMLI, This paper proposes several designs for a reliable infra-red based communication techniques for swarm robotic applications. The communication system was deployed on an autonomous miniature mobile robot (AMiR), a swarm robotic platform developed earlier. In swarm applications, all participating robots must be able to communicate and share data. Hence a suitable communication medium and a reliable technique are required. This work uses infrared radiation for transmission of swarm robots messages. Infrared transmission methods such as amplitude and frequency modulations will be presented along with experimental results. Finally the effects of the modulation techniques and other parameters on collective behavior of swarm robots will be analyzed. Tue, 30 Nov 2010 00:00:00 +0200 http://dx.doi.org/10.4316/aece.2010.04011 http://dx.doi.org/10.4316/aece.2010.04011 E., MASEHIAN, D., SEDIGHIZADEH, In this paper two novel Particle Swarm Optimization (PSO)-based algorithms are presented for robot path planning with respect to two objectives, the shortest and smoothest path criteria. The first algorithm is a hybrid of the PSO and the Probabilistic Roadmap (PRM) methods, in which the PSO serves as the global planner whereas the PRM performs the local planning task. The second algorithm is a combination of the New or Negative PSO (NPSO) and the PRM methods. Contrary to the basic PSO in which the best position of all particles up to the current iteration is used as a guide, the NPSO determines the most promising direction based on the negative of the worst particle position. The two objective functions are incorporated in the PSO equations, and the PSO and PRM are combined by adding good PSO particles as auxiliary nodes to the random nodes generated by the PRM. Both the PSO+PRM and NPSO+PRM algorithms are compared with the pure PRM method in path length and runtime. The results showed that the NPSO has a slight advantage over the PSO, and the generated paths are shorter and smoother than those of the PRM and are calculated in less time. Tue, 30 Nov 2010 00:00:00 +0200 http://dx.doi.org/10.4316/aece.2010.04012 http://dx.doi.org/10.4316/aece.2010.04012 V., MUNTEANU, D., TARNICERIU, G., ZAHARIA, The linear, binary, block codes with no equally likely probabilities for the binary symbols are analyzed. The encoding graph for systematic linear block codes is proposed. These codes are seen as sources with memory and the information quantities H(S,X), H(S), H(X), H(X|S), H(S|X), I(S,X) are derived. On the base of these quantities, the code performances are analyzed. Tue, 30 Nov 2010 00:00:00 +0200 http://dx.doi.org/10.4316/aece.2010.04013 http://dx.doi.org/10.4316/aece.2010.04013 B., OH, Y., NA, J., YANG, S., PARK, J., NANG, J., KIM, Suggesting more efficient driving routes generate benefits not only for individuals by saving commute time, but also for society as a whole by reducing accident rates and social costs by lessening traffic congestion. In this paper, we suggest a new route search algorithm based on a genetic algorithm which is more easily installable into mutually communicating car navigation systems, and validate its usefulness through experiments reflecting real-world situations. The proposed algorithm is capable of searching alternative routes dynamically in unexpected events of system malfunctioning or traffic slow-downs due to accidents. Experimental results demonstrate that our algorithm searches the best route more efficiently and evolves with universal adaptability. Tue, 30 Nov 2010 00:00:00 +0200 http://dx.doi.org/10.4316/aece.2010.04014 http://dx.doi.org/10.4316/aece.2010.04014 M., MIKHOV, T., GEORGIEV, An approach to dual-zone speed control of DC motor electric drives is presented in this paper. The new point is that in the syntheses of controllers a combination between setting of closed-loop system poles (modal control) and optimal control through the quadratic quality criterion minimization is applied. Optimal modal control is achieved whereat a new type of complex criterion for selection of the functional is used. This approach allows taking into consideration the controlled object parameters' change at determination of the optimal modal controller coefficients when speed is regulated above the rated value. The research carried out as well as the results obtained can be used in the design, optimization and tuning of such types of drive systems. Tue, 30 Nov 2010 00:00:00 +0200 http://dx.doi.org/10.4316/aece.2010.04015 http://dx.doi.org/10.4316/aece.2010.04015 V. M., DESPOTOVIC, Z. H., PERIC, L., VELIMIROVIC, V. D., DELIC, In this article DPCM (Differential Pulse Code Modulation) speech coding scheme with a simple switched first order predictor is presented. Adaptation of the quantizer to the signal variance is performed for each particular frame. Each frame is classified as high or low correlated, based on the value of the correlation coefficient, then the selection of the appropriate predictor coefficient and bitrate is performed. Low correlated frames are encoded with a higher bitrate, while high correlated frames are encoded with a lower bitrate without the objectionable loss in quality. Theoretical model and experimental results are provided for the proposed algorithm. Tue, 30 Nov 2010 00:00:00 +0200 http://dx.doi.org/10.4316/aece.2010.04016 http://dx.doi.org/10.4316/aece.2010.04016 F., BASCIFTCI, O. F., HATAY, One of the most effective methods of achieving savings in electrically-operated systems and increasing the efficiency is reactive power compensation. With the presently enforced regulation, compensation is mandatory for industrial consumers and it is done at certain power intervals, there is no regulation for residences and small scale enterprises on this subject. In this study, measurement of the reactive power in single-phase systems has been developed, as well as calculation for directing for energy saving through a microcontroller. In the implemented system, the phase difference between the current and voltage is measured, the outputs are made fuzzy according to the amount of the consumed reactive power and directing to saving is done Implementation results demonstrated that the designed system has a simple structure and small dimensions, it brings up the power coefficient of the system to the optimum level, it reduces the faults to minimum and reduces the cost. Furthermore, the portability feature of the system makes it possible to prevent adverse situations that may happen when no reactive power is consumed or when no device is being used. Tue, 30 Nov 2010 00:00:00 +0200 http://dx.doi.org/10.4316/aece.2010.04017 http://dx.doi.org/10.4316/aece.2010.04017 A. A., MOGHADDAM, A. R., SEIFI, Renewable energies such as wind and solar have become the most attractive means of electricity generation nowadays. Social and environmental benefits as well as economical issues result in further utilization of such these energy resources. In this regard, wind energy plays an important roll in operation of small-scale power systems like Micro Grid. On the other hand, wind stochastic nature in different time and place horizons, makes accurate forecasting of its behavior an inevitable task for market planners and energy management systems. In this paper an advanced strategy for wind speed estimation has been purposed and its superior performance is compared to that of conventional methods. The model is based on linear predictive filtering and image processing principles using 2-D FIR filters. To show the efficiency of purposed predictive model different FIR filters are designed and tested through similar data. Wind speed data have been collected during the period January 1, 2009 to December 31, 2009 from Casella automatic weather station at Plymouth. It is observed that 2-D FIR filters act more accurately in comparison with 1-D conventional representations; however, their prediction ability varies considerably through different filter sizing. Tue, 30 Nov 2010 00:00:00 +0200 http://dx.doi.org/10.4316/aece.2010.04018 http://dx.doi.org/10.4316/aece.2010.04018 A., TOFIGHI, A., KALANTAR, In this paper, a DC hybrid power source composed of PEM fuel cell as main source, Li-ion battery storage as transient power source and their power electronic interfacing is modelled based on Euler-Lagrange framework. Subsequently, adaptive passivity-based controllers are synthesized using the energy shaping and damping injection technique. Local asymptotic stability is insured as well. In addition, the power management system is designed in order to manage power flow between components. Evaluation of the proposed system and simulation of the hybrid system are accomplished using MATLAB/Simulink. Afterwards, linear PI controllers are provided for the purpose of comparison with proposed controllers responses. The results show that the outputs of hybrid system based on adaptive passivity-based controllers have a good tracking response, low overshoot, short settling time and zero steady-state error. The comparison of results demonstrates the robustness of the proposed controllers for reference DC voltage and resistive load changes. Tue, 30 Nov 2010 00:00:00 +0200 http://dx.doi.org/10.4316/aece.2010.04019 http://dx.doi.org/10.4316/aece.2010.04019 D., OROS, V., VASIC, D., MARCETIC, F., KULIC, In this paper, the parameter sensitivity analysis of shaft-sensorless induction motor drive with natural field orientation (NFO) scheme is performed. NFO scheme calculates rotor flux position using the rotor flux vector reference only, does not require significant processor power and therefore it is suitable for low cost shaft sensorless drives. This concept also eliminates the need for sensitive stator voltage vector integration and it is usable in low rotor speed range. However, low speeds are coupled with low stator voltage amplitudes, which inflate the NFO scheme sensitivity to an error in stator resistance parameter. Similar problems can also take place if mutual inductance parameter is detuned, but this time in whole speed range. This paper investigates the influence of each parameter error on the NFO control steady state characteristics and dynamic performance. Tue, 30 Nov 2010 00:00:00 +0200 http://dx.doi.org/10.4316/aece.2010.04020 http://dx.doi.org/10.4316/aece.2010.04020 I., FIROIU, C., NAFORNITA, J. M., BOUCHER, A., ISAR, The aim of this paper is the association of a new variant of Hyperanalytic Wavelet Transform (HWT) with a maximum a posteriori (MAP) filter, named bishrink for the denoising of images affected by additive white Gaussian noise (AWGN). The best results are obtained with the biorthogonal mother wavelets Daubechies 9/7. Tue, 30 Nov 2010 00:00:00 +0200 http://dx.doi.org/10.4316/aece.2010.04021 http://dx.doi.org/10.4316/aece.2010.04021 N. C., LENIN, R., ARUMUGAM, V., CHADRESEKAR, In this paper, the results of a finite element analysis are carried out on an new stator geometry of a three phase longitudinal flux Linear Switched Reluctance Motor (LSRM). In the new geometry, pole shoes are affixed to the stator poles. Static and dynamic characteristics for the proposed structure have been highlighted. Motor performance for variable load conditions is discussed. Frequency spectrum analyses of force profile using the fast Fourier transform (FFT) are described to predict the vibration frequencies. The 2-Dimensional (2-D) finite element analysis (FEA) and the experimental results of this paper prove that LSRMs are one of the strong candidates for linear propulsion drives. Tue, 30 Nov 2010 00:00:00 +0200 http://dx.doi.org/10.4316/aece.2010.04022 http://dx.doi.org/10.4316/aece.2010.04022 O., BALTA, D., COSTANDACHE, M., RAU, A., IFTEMIE, I., RAU, The paper presents a comparative study of the methods used to control and compensate the direct and alternative magnetic fields. Two frequently used methods in the electromagnetic compatibility of the complex biomagnetism installations were analyzed. The two methods refer to the use of inductive magnetic field sensors (only for alternative fields) and of fluxgate magnetometers as active transducers which measures both the direct and alternative components of the magnetic field. The applications of the dynamic control of the magnetic field are: control of the magnetic field of the military ships, control of parasite magnetic field produced by power transformers and the electrical networks, protection of the mass spectrometers, electronic microscopes, SQUID and optical pumping magnetometers for applications in biomagnetism. Tue, 30 Nov 2010 00:00:00 +0200 http://dx.doi.org/10.4316/aece.2010.04023 http://dx.doi.org/10.4316/aece.2010.04023 Y. K., RENANI, B., VAHIDI, H. A., ABYANEH, Development of distribution network and power consumption growth, increase voltage drop on the line impedance and therefore voltage drop in system buses. In some cases consumption is so high that voltage in some buses exceed from standard. In this paper, effect of the fuel cell and photovoltaic hybrid system on distribution network for solving expressed problem is studied. For determining the capacity of each distributed generation source, voltage limitation on the bus voltages under different conditions is considered. Simulation is done by using DIgSILENT software on the part of the 20 kV real life Sirjan distribution system. In this article, optimum location with regard to system and environmental conditions are studied in two different viewpoints. Tue, 30 Nov 2010 00:00:00 +0200 http://dx.doi.org/10.4316/aece.2010.04024 http://dx.doi.org/10.4316/aece.2010.04024 S., IVANOV, In the case of the classical direct torque control (DTC) of the induction motor, the minimum switching period of the inverter is equal with the sampling period of the control system. Due to this intrinsic characteristic, competitive real time control can be achieved only by using high performance control systems. If moderate performances system is used, the behavior of the drive is unsatisfactory, even inacceptable. The paper proposes continuous variants of the DTC, obtained by replacing the discrete controllers specific to the classical DTC with two or three continuous controllers, one of them being the speed controller. Thus, the sampling period of the control system is decoupled by the switching period of the inverter and a moderate performance real time control system can be used. Tue, 30 Nov 2010 00:00:00 +0200 http://dx.doi.org/10.4316/aece.2010.04025 http://dx.doi.org/10.4316/aece.2010.04025 P. L., OGRUTAN, M., ROMANCA, C., GERIGAN, G., MORARIU, L. E., ACIU, The paper presents a Radon monitoring system. The system is designed for real time multiple location monitoring. The paper presents in the first part a method and an instrument for measuring radon concentration in air. Simulink simulations and implementation of the measurement principle are presented. Instrument position is determined by GPS and transmitted over GPRS along with the measurements results. Data management is accomplished by a software component of the system. The paper presents as an application, an investigation on nanomaterials to be used for Radon mitigation. Tue, 30 Nov 2010 00:00:00 +0200 http://dx.doi.org/10.4316/aece.2010.04026 http://dx.doi.org/10.4316/aece.2010.04026 Y. O., USHENKO, Y. Y., TOMKA, Y. I., MARCHUK, V. O., BALANETCKA, Performed in this work are complex statistical and fractal analyses of phase properties inherent to birefringence networks of liquid crystals consisting of optically-thin layers prepared from human bile. Within the framework of a statistical approach, the authors have investigated values and ranges for changes of statistical moments of the 1-st to 4-th orders that characterize coordinate distributions for phase shifts between orthogonal components of amplitudes inherent to laser radiation transformed by human bile with various pathologies. Using the Gramm-Charlie method, ascertained are correlation criteria for differentiation of phase maps describing pathologically changed liquid-crystal networks. In the framework of the fractal approach, determined are dimensionalities of self-similar coordinate phase distributions as well as features of transformation of logarithmic dependences for power spectra of these distributions for various types of human pathologies. Tue, 30 Nov 2010 00:00:00 +0200 http://dx.doi.org/10.4316/aece.2010.04027 http://dx.doi.org/10.4316/aece.2010.04027 D., KAIRUS, R., WAMKEUE, B., BELMADANI, M., BENGHANEM, This paper focuses on wind energy conversion system (WECS) analysis and control for power generation along with problems related to the mitigation of harmonic pollution in the grid using a variable-speed structure control of the doubly fed induction generator (DFIG). A control approach based on the so-called sliding mode control (SMC) that is both efficient and suitable is used for power generation control and harmonic-current compensation. The WECS then behaves as an active power filter (APF). The method aims at improving the overall efficiency, dynamic performance and robustness of the wind power generation system. Simulation results obtained on a 20-kW, 380-V, 50-Hz DFIG confirm the effectiveness of the proposed approach. Tue, 30 Nov 2010 00:00:00 +0200 http://dx.doi.org/10.4316/aece.2011.01001 http://dx.doi.org/10.4316/aece.2011.01001 Y. O., USHENKO, Y. Y., TOMKA, I. Z., MISEVICH, A.-P., ANGELSKY, V. T., BACHINSKY, Adduced in this work are the results of investigation aimed at analysis of coordinate distributions for azimuths and ellipticity of polarization (polarization maps) in laser images of three types of phase-inhomogeneous layers (PhIL), namely: rough, ground and bulk scattering layers. To characterize polarization maps for all the types of PhIL, the authors have offered to use three groups of parameters: statistical moments of the first to fourth orders, autocorrelation functions, logarithmic dependences for power spectra related to distributions of azimuths and ellipticity of polarization inherent to PhIL laser images. Ascertained are the criteria for diagnostics and classification of PhIL optical properties. Sun, 27 Feb 2011 00:00:00 +0200 http://dx.doi.org/10.4316/aece.2011.01002 http://dx.doi.org/10.4316/aece.2011.01002 K., ZAPLATILEK, M., TALPA, J., LEUCHTER, The article describes an original method of optimization algorithms testing and convergence. The method is based on so-called stacked histogram. Stacked histogram is a histogram with its features marked by a chosen colour scheme. Thus, the histogram maintains the information on the input digital sequence. This approach enables an easy identification of the hidden defects in the random process statistical distribution. The stacked histogram is used for the testing of the convergent quality of various optimization techniques. Its width, position and colour scheme provides enough information on the chosen algorithm optimization trajectory. Both the classic iteration techniques and the stochastic optimization algorithm with the adaptation were used as examples. Sun, 27 Feb 2011 00:00:00 +0200 http://dx.doi.org/10.4316/aece.2011.01003 http://dx.doi.org/10.4316/aece.2011.01003 M., RAU, A., IFTEMIE, O., BALTAG, D., COSTANDACHE, The paper presents the results concerning the utilization of a new class of composite textile materials with electromagnetic properties and the possibility of their utilization in the production of electromagnetic field protective equipment. The experimental and theoretical results concerning the electromagnetic characterization of a new textile material with composite structure are presented also considering the following aspects: - evaluation of the possibilities to use amorphous magnetic microwires in electromagnetic shielding; - study of the electromagnetic properties of the composite textile material, especially the electromagnetic field shielding, reflection and polarization; - determination of the frequency range within which these properties can be used in the realization of materials for the protection against electromagnetic fields. The experimental results of a material sample and a phantom for applications are connected with shielding in the frequency range used in mobile communications. Sun, 27 Feb 2011 00:00:00 +0200 http://dx.doi.org/10.4316/aece.2011.01004 http://dx.doi.org/10.4316/aece.2011.01004 R. G., BOZOMITU, N., COJAN, In this paper a new low voltage 5th order Gm-C Bessel type low-pass filter (LPF) with auto-tuning loop and higher dynamic range, designed in CMOS technology, is presented. The cut-off frequency can be tuned in (10-42)MHz range by modifying the values of the grounded capacitors using a digital logic. The proposed structure is based on an auto-tuning loop in order to maintain the Gm/C ratio independent of the process, supply voltage and temperature variations, assuring the cut-off frequency of the LPF independently of these factors. The proposed 5th order Gm-C Bessel type low-pass filter provides 5% variation of the cut-off frequency in all critical corners, a 400mVpp(diff) dynamic range, THD less than 1% and 21.6mW power consumption from 1.8V supply voltage. The simulations performed in 65nm CMOS process confirm the theoretical results. Sun, 27 Feb 2011 00:00:00 +0200 http://dx.doi.org/10.4316/aece.2011.01005 http://dx.doi.org/10.4316/aece.2011.01005 N., POUDYAL, H. C., LEE, Y. J., KWON, B. S., LEE, In this paper a novel schedulability criteria is developed to provide Quality of Service (QoS) guarantees in terms of both minimum available bandwidth and maximum tolerated packet delay as required by the real-time traffic class. The contribution makes use of a measurement based admission control scheme at the base station of the 802.16m based 4G IMT-advanced network by considering the effects of various kinds of delays including the channel access delay, queuing delay and MAC layer transmission delay on the system's end to end delay. The paper also provides a way for the mobile station to proactively increase the chances of success of bandwidth grants by predicting in advance whether its bandwidth request will be approved by the base station, and then modifying or suspending its bandwidth request in case the chances of success is not favorable at that instant. Sun, 27 Feb 2011 00:00:00 +0200 http://dx.doi.org/10.4316/aece.2011.01006 http://dx.doi.org/10.4316/aece.2011.01006 L., ZOU, J., LASEBY, Z., HE, The principal objective of this investigation is to facilitate minimum variance distortionless response (MVDR) beamforming technique for a cylindrical conformal array geometry. An array of directional radiating elements is postulated to cover a surface typical of the cylinder of an aircraft or missile. Borrowing the analysis of conformal array antennas, the authors first derive a deterministic expression that describes the beam pattern of arbitrary weighted cylindrical conformal array. Then, making use of the MVDR beamforming, we derive the beamformer for uniform linear array (ULA) of directional antennas which are different from the traditional omnidirectional elements. Thus, the pattern of a directional element is synthesized by the antennas on the same ring array, and we design the MVDR beamformer, which uses MVDR beamforming for ULA of the synthesized pattern. To demonstrate the validity of the method, and cylinder arrays are constructed and experimental results agree well with theoretical expectations. Sun, 27 Feb 2011 00:00:00 +0200 http://dx.doi.org/10.4316/aece.2011.01007 http://dx.doi.org/10.4316/aece.2011.01007 V. V., PATRICIU, I., BICA, M., TOGAN, S. V., GHITA, Online digital goods distribution environment lead to the need for a system to protect digital intellectual property. Digital Rights Management (DRM) is the system born to protect and control distribution and use of those digital assets. The present paper is a review of the current state of DRM, focusing on architectural design, security technologies, and important DRM deployments. The paper primarily synthesizes DRM architectures within a general framework. We also present DRM ecosystem as providing a better understanding of what is currently happening to content rights management from a technological point of view. This paper includes conclusions of several DRM initiative studies, related to rights management systems with the purpose of identifying and describing the most significant DRM architectural models. The basic functions and processes of the DRM solutions are identified. Sun, 27 Feb 2011 00:00:00 +0200 http://dx.doi.org/10.4316/aece.2011.01008 http://dx.doi.org/10.4316/aece.2011.01008 F., KULIC, D., MATIC, B., DUMNIC, V., VASIC, This paper reports an automated procedure for the design of an optimal fuzzy logic controller to be used as an induction motor speed controller. The procedure consists of selection of a suitable well known fuzzy logic controller and tuning via particle swarm optimization optimal for the selected criteria. In this way the time required for tuning of the controller is significantly reduced in comparison with trial and error methods. As a benchmark a proportional-integral (PI) controller is used. The PI controller is tuned via the symmetrical optimum procedure, the standard procedure for tuning a speed controller of an induction motor. Simulation results are obtained via a mathematical model developed in Matlab/Simulink. Experimental verification is carried out with a laboratory model based on the DS1104 digital control card. To minimize iron losses and to provide better motor performance for low loads, flux is reduced from nominal and speed is kept below nominal. Results are presented in tables and graphics. The optimal fuzzy logic controller provides a slight practical advantage. Sun, 27 Feb 2011 00:00:00 +0200 http://dx.doi.org/10.4316/aece.2011.01009 http://dx.doi.org/10.4316/aece.2011.01009 F., CONSTANTINESCU, A. G., GHEORGHE, M., NITESCU, A., FLOREA, O., LLOPIS, P., TARAS, The large signal operation of the bulk acoustic wave (BAW) resonators is characterized by the amplitude-frequency effect and the intermodulation effect. The measurement of these effects, together with that of the small signal frequency characteristic, are used in this paper for the parameter identification of the nonlinear circuit models developed previously by authors. As the resonator has been connected to the measurement bench by wire bonding, the parasitic elements of this connection have been taken into account, being estimated solving some electrical and magnetic field problems. Sun, 27 Feb 2011 00:00:00 +0200 http://dx.doi.org/10.4316/aece.2011.01010 http://dx.doi.org/10.4316/aece.2011.01010 B. S., KIREI, M. D., TOPA, I., MURESAN, I., HOMANA, N., TOMA, Blind source separation of convolutive mixtures is used as a preprocessing stage in many applications. The aim is to extract individual signals from their mixtures. In enclosed spaces, due to reverberation, audio signal mixtures are considered to be convolutive ones. Time domain algorithms (as neural network based blind source separation) are not suitable for signal recovery from convolutive mixtures, thus the need of frequency domain or subband processing arise. We propose a subband approach: first the mixtures are split to several subbands, next time-domain blind source separation is carried out in each subband, finally the recovered sources are recomposed from the subbands. The major drawback of the subband approach is the unknown order of the recovered sources. Regardless of this undesired phenomenon the subband approach is faster and more stable than the simple time domain algorithm. Sun, 27 Feb 2011 00:00:00 +0200 http://dx.doi.org/10.4316/aece.2011.01011 http://dx.doi.org/10.4316/aece.2011.01011 A., METATLA, S., BENZAHIOUL, T., BAHI, D., LEFEBVRE, This work concerns the monitoring and diagnosis of faults in induction motors. We develop an approach based on residual analysis of stator currents to detect and diagnose faults eccentricity static, dynamic and mixed in three phase induction motor. To simulate the behavior of motor failure, a model is proposed based on the approach of magnetically coupled coils. The simulation results show the importance of the approach applied for the detection and diagnosis of fault in three phase induction motor. Sun, 27 Feb 2011 00:00:00 +0200 http://dx.doi.org/10.4316/aece.2011.01012 http://dx.doi.org/10.4316/aece.2011.01012 G., CRACIUNAS, In this paper there are outlined the automatic speed adjusting control system performances of a two-phase induction machine (TPIM) with direct field oriented control and using adaptive methods for the estimation of the rotoric flux spatial vector. Starting from the linear model of the two-phase induction machine, there are studied in comparison two solutions used in automatic speed adjusting control: one using the deduction of the spatial vector components of the rotoric flux by indirect field determination and the second using adaptive methods for rotoric flux spatial vector estimation from the two-phase components of the stator voltage and current. Thus there are emphasized the performances of the reduced order Gopinath observer. The operation of the automatic speed adjusting control system, based on solid adaptive estimation of the rotoric flux and indirect determination of the field, was studied using Matlab/SIMULINK real time simulation. Sun, 27 Feb 2011 00:00:00 +0200 http://dx.doi.org/10.4316/aece.2011.01013 http://dx.doi.org/10.4316/aece.2011.01013 K.-H., KIM, J.-H., KIM, The work in this paper pertains to domain independent vocabulary generation and its use in category-based small footprint Language Model (LM). Two major constraints of the conventional LMs in the embedded environment are memory capacity limitation and data sparsity for the domain-specific application. This data sparsity adversely affects vocabulary coverage and LM performance. To overcome these constraints, we define a set of domain independent categories using a Part-Of-Speech (POS) tagged corpus. Also, we generate a domain independent vocabulary based on this set using the corpus and knowledge base. Then, we propose a mathematical framework for a category-based LM using this set. In this LM, one word can be assigned assign multiple categories. In order to reduce its memory requirements, we propose a tree-based data structure. In addition, we determine the history length of a category n-gram, and the independent assumption applying to a category history generation. The proposed vocabulary generation method illustrates at least 13.68% relative improvement in coverage for a SMS text corpus, where data are sparse due to the difficulties in data collection. The proposed category-based LM requires only 215KB which is 55% and 13% compared to the conventional category-based LM and the word-based LM, respectively. It successively improves the performance, achieving 54.9% and 60.6% perplexity reduction compared to the conventional category-based LM and the word-based LM in terms of normalized perplexity. Sun, 27 Feb 2011 00:00:00 +0200 http://dx.doi.org/10.4316/aece.2011.01014 http://dx.doi.org/10.4316/aece.2011.01014 L., TRIFINA, D., TARNICERIU, A.-M., ROTOPANESCU, This paper analyzes the extrinsic information scaling coefficient influence on double-iterative decoding algorithm for space-time turbo codes with large number of antennas. The max-log-APP algorithm is used, scaling both the extrinsic information in the turbo decoder and the one used at the input of the interference-canceling block. Scaling coefficients of 0.7 or 0.75 lead to a 0.5 dB coding gain compared to the no-scaling case, for one or more iterations to cancel the spatial interferences. Sun, 27 Feb 2011 00:00:00 +0200 http://dx.doi.org/10.4316/aece.2011.01015 http://dx.doi.org/10.4316/aece.2011.01015 V., ZHURBENKO, Among the various breast imaging modalities for breast cancer detection, microwave imaging is attractive due to the high contrast in dielectric properties between the cancerous and normal tissue. Due to this reason, this modality has received a significant interest and attention from the microwave community. This paper presents the survey of the ongoing research in the field of microwave imaging of biological tissues, with major focus on the breast tumor detection application. The existing microwave imaging systems are categorized on the basis of the employed measurement concepts. The advantages and disadvantages of the implemented imaging techniques are discussed. The fundamental tradeoffs between the various system requirements are indicated. Some strategies to overcome these limitations are outlined. Sun, 27 Feb 2011 00:00:00 +0200 http://dx.doi.org/10.4316/aece.2011.01016 http://dx.doi.org/10.4316/aece.2011.01016 P., MATIC, S. N., VUKOSAVIC, The paper describes sensorless speed controlled continuous Direct Torque Control (DTC) Induction Motor (IM) drive in the field weakening regime. Drive comprises an inner torque loop and an outer speed loop. Torque control is based on Proportional - Integral (PI) controller with adaptive Gain Scheduling (GS) parameters. The GS PI control provides full DC link voltage utilization and a robust disturbance rejection along with a fast torque response. Outer speed loop has a PI regulator with the gains selected so as to obtain a fast and strictly aperiodic response. Proposed drive fully utilizes the available DC bus voltage. The paper comprises analytical considerations, simulation results, and detailed description of the implementation steps. Experimental verification of the proposed solution is conducted on a fixed point Digital Signal Processor (DSP) platform. Sun, 27 Feb 2011 00:00:00 +0200 http://dx.doi.org/10.4316/aece.2011.01017 http://dx.doi.org/10.4316/aece.2011.01017 V. A., KATIC, S. V., MUJOVIC, V. M., RADULOVIC, J. S., RADOVIC, Harmonics current emission from personal computers (PCs) is of special interest to power quality researchers, due to their wide spread application and the fact that they are usually concentrated in large groups (clusters). The input current total harmonic distortion (THDI) dependence on number of connected PCs in a cluster (NPC) is affected by network parameters and load side parameters of each cluster's PC simultaneously. As the impact of grid parameters on the THDI=f(NPC) dependence is analyzed in the author's previous papers, special emphasis is given on the impact of the DC side smoothing capacitor (C) in PCs power supply unit. For engineering application it is convenient to present the THDI=f(NPC) function with simple mathematical expressions which include these effects. In the paper authors are proposing an improved mathematical expression to presents impact of load side (DC capacitance) parameters. To achieve this goal, results of the measurements of harmonic emission from a large computer center with 167 clustered PCs and the computer simulation for even larger number of PCs are used. Sun, 27 Feb 2011 00:00:00 +0200 http://dx.doi.org/10.4316/aece.2011.01018 http://dx.doi.org/10.4316/aece.2011.01018 J., WANG, Y., LI, Q., PENG, Network-on-Chip (NoC) communication architecture is proposed to resolve the bottleneck of Multi-processor communication in a single chip. In this paper, a performance analytical model using Semi-Markov Process (SMP) is presented to obtain the NoC performance. More precisely, given the related parameters, SMP is used to describe the behavior of each channel and the header flit routing time on each channel can be calculated by analyzing the SMP. Then, the average packet latency in NoC can be calculated. The accuracy of our model is illustrated through simulation. Indeed, the experimental results show that the proposed model can be used to obtain NoC performance and it performs better than the state-of-art models. Therefore, our model can be used as a useful tool to guide the NoC design process. Sun, 27 Feb 2011 00:00:00 +0200 http://dx.doi.org/10.4316/aece.2011.02001 http://dx.doi.org/10.4316/aece.2011.02001 T., QIU, F., XIA, L., FENG, G., WU, B., JIN, Path planning is one of the important factors that affect data transmission and processing in wireless sensor networks (WSNs). This paper addresses this issue by means of the paths delay analysis. Considering that WSNs are used for temperature monitoring, we model the WSNs using the open queueing network theory and analyze the paths delay based on the model. An iterative approximation algorithm is proposed for the qualitative analysis of the packet arrival rate of sensor nodes. According to the capacity and redundancy of nodes along the path, the destination node search trees are created for pre-selecting the transmission paths. Then the end-to-end delays of the pre-selected node paths and the average delay of sub-queueing networks are calculated. The optimal path and the assistant path for data transmission in WSNs could be obtained on the basis of the delay analysis. Numerical results demonstrate the effectiveness of the proposed approach. Mon, 30 May 2011 00:00:00 +0300 http://dx.doi.org/10.4316/aece.2011.02002 http://dx.doi.org/10.4316/aece.2011.02002 Y., TIAN, Z., TANG, According to the characteristics of wireless meter reading system, an energy-balanced and energy-efficient steady clustering routing algorithm (EBSC, Energy-Balanced Steady Clustering) is proposed. In the clustering mechanism, the current cluster head nodes determine cluster head nodes for next round according to the residual energy of the cluster members. In the next round, each non-cluster head node decides the cluster to which it will belong according to energy-distance function. The cluster head nodes send data to base station by the communication model of single hop and multi-hop that is decided according to the criterion of minimum energy consumption. In EBSC algorithm, the number of cluster head nodes generated in each round is very steady, and EBSC combines the advantage both distributed and centralized clustering algorithm. Experimental results show that the proposed routing algorithm not only efficiently uses limited energy of network nodes, but also well balances energy consumption of all nodes, and significantly prolongs network lifetime. Mon, 30 May 2011 00:00:00 +0300 http://dx.doi.org/10.4316/aece.2011.02003 http://dx.doi.org/10.4316/aece.2011.02003 T., PANA, O., STOICUTA, The paper presents a synthesis of an extended Gopinath observer (EGO) and analyzes the asymptotic stability of a squirrel-cage induction motor vector control system with an EGO in its loop. The considered control system is based on the direct rotor flux orientation method (DFOC) and the study of stability is based upon the linearization theorem applied around the equilibrium points of the control system, emphasizing the estimated variation domain of the rotor resistance for which the control system remains asymptotically stable. Mon, 30 May 2011 00:00:00 +0300 http://dx.doi.org/10.4316/aece.2011.02004 http://dx.doi.org/10.4316/aece.2011.02004 M., BIGDELI, M., VAKILIAN, E., RAHIMPOUR, Transfer function (TF) is an acknowledged method for power transformer mechanical faults detection. However the past published works mostly discovered how to specify the faults levels and paid less attention to detection of the type of faults using comparison of TFs. whereas, it seems important for most of the applications to specify the type of fault without opening the unit. This paper presents a new method based on vector fitting (VF) to compare the TFs and specify the type, level and location of the fault. For development of the method, and its verification the required measurements are carried out on four model transformers; under intact condition, and under different fault conditions (axial displacement, radial deformation, disc space variation and short circuit of winding) and the TFs are determined. Employing VF, the coefficients of TFs are determined with the required accuracy. Using those coefficients, a new index is introduced to specify the type, level and location of the fault in the winding. Convincingly good results were obtained. Therefore it is believed that this finding could be helpful in fault diagnosis in actual power transformer windings. Mon, 30 May 2011 00:00:00 +0300 http://dx.doi.org/10.4316/aece.2011.02005 http://dx.doi.org/10.4316/aece.2011.02005 M., DELSHAD, This paper presents a new zero voltage switching current-fed DC-DC converter with high voltage gain. In this converter all switches (main and auxiliary) turn on under zero voltage switching and turn off under almost zero voltage switching due to snubber capacitor. Furthermore, the voltage spike across the main switch due to leakage inductance of forward transformer is absorbed. The flyback transformer which is connected to the output in series causes to high voltage gain and less voltage stress on the power devices. Considering high efficiency and voltage gain of this converter, it is suitable for green generated systems such as fuel cells or photovoltaic systems. The presented experimental results verify the integrity of the proposed converter. Mon, 30 May 2011 00:00:00 +0300 http://dx.doi.org/10.4316/aece.2011.02006 http://dx.doi.org/10.4316/aece.2011.02006 A. S., MOLAHOSSEINI, The residue number system (RNS) is an unconventional number system which can be used to achieve high-performance hardware implementations of special-purpose computation systems such as digital signal processors. The moduli set {2n-1, 2n, 2n+1, 22n+1-1} has been recently suggested for RNS to provide large dynamic range with low-complexity, and enhancing the speed of internal RNS arithmetic circuits. But, the residue-to-binary converter of this moduli set relies on high conversion delay. In this paper, a new residue-to-binary converter for the moduli set {2n-1, 2n, 2n+1, 22n+1-1} using an adder-based implementation of new Chinese remainder theorem-1 (CRT-I) is presented. The proposed converter is considerably faster than the original residue-to-binary converter of the moduli set {2n-1, 2n, 2n+1, 22n+1-1}; resulting in decreasing the total delay of the RNS system. Mon, 30 May 2011 00:00:00 +0300 http://dx.doi.org/10.4316/aece.2011.02007 http://dx.doi.org/10.4316/aece.2011.02007 H., MOKHLIS, H., MOHAMAD, H., LI, A. H. A., BAKAR, A voltage sags matching to locate a fault for underground distribution network is presented in this paper. Firstly the method identifies the faulted section by matching a voltage sags measured at the primary substation during a fault with pre-developed voltage sag database. From the identified faulted section, the distance of a fault from sending-end is calculated. The problem of multiple sections is addressed by ranking approach. Test results on an underground distribution network shows most faults can be located by the first attempt within high accuracy distance. Only few faulted sections found by the second attempt. Since the method is using only voltage sag data, monitored at the primary substation, the method is considers economical to be implemented for a rural distribution network. Mon, 30 May 2011 00:00:00 +0300 http://dx.doi.org/10.4316/aece.2011.02008 http://dx.doi.org/10.4316/aece.2011.02008 V., SURDUCAN, E., SURDUCAN, R., CIUPA, Fine control of microwave power radiation in medical and scientific applications is a challenging task. Since a commercial Continuous Wave (CW) magnetron is the most inexpensive microwave device available today on the market, it becomes the best candidate for a microwave power generator used in medical diathermy and hyperthermia treatments or high efficiency chemical reactions using microwave reactors as well. This article presents a new method for driving a CW magnetron with short pulses, using a modified commercial Zero Voltage Switching (ZVS) inverter, software driven by a custom embedded system. The microwave power generator designed with this method can be programmed for output microwave pulses down to 1% of the magnetron's power and allows microwave low frequency pulse modulation in the range of human brain electrical activity, intended for medical applications. Microwave output power continuous control is also possible with the magnetron running in the oscillating area, using a dual frequency Pulse Width Modulation (PWM), where the low frequency PWM pulse is modulating a higher resonant frequency required by the ZVS inverter's transformer. The method presented allows a continuous control of both power and energy (duty-cycle) at the inverter's output. Mon, 30 May 2011 00:00:00 +0300 http://dx.doi.org/10.4316/aece.2011.02009 http://dx.doi.org/10.4316/aece.2011.02009 Y. O., USHENKO, Y. Y., TOMKA, O. V., DUBOLAZOV, V. O., BALANETSKA, A. V., KARACHEVTSEV, A.-P., ANGELSKY, The possibilities of the local wavelet-analysis of polarization-inhomogeneous laser image of human blood plasma were considered. The set of statistics, correlation and fractal parameters of the distributions of wavelet-coefficients that are characterize different scales of the polarization maps of polycrystalline networks of amino acids of blood plasma were defined. The criteria for the differentiation of the transformation of birefringence optical-anisotropic structures of blood plasma at different scales of their geometric dimensions were determined. Mon, 30 May 2011 00:00:00 +0300 http://dx.doi.org/10.4316/aece.2011.02010 http://dx.doi.org/10.4316/aece.2011.02010 M., HERCEG, R., GRBIC, T., SVEDEK, In this paper, the characteristic function (CF) method is used to derive the symbol error rate (SER) expression for time-hopping impulse radio ultra-wideband (TH-IR-UWB) systems with a biorthogonal pulse position modulation (BPPM) scheme in the presence of a multi-user interference (MUI). The derived expression is validated with the Monte-Carlo simulation and compared with orthogonal PPM. Moreover, the analytical results are compared with the Gaussian approximation (GA) of MUI which is shown to be inaccurate for a medium and large signal-to-noise ratio (SNR). It is also shown that the BPPM scheme outperforms the PPM scheme for all SNR. At the end, the influence of different system parameters on the BPPM performance is analyzed. Mon, 30 May 2011 00:00:00 +0300 http://dx.doi.org/10.4316/aece.2011.02011 http://dx.doi.org/10.4316/aece.2011.02011 A. H., ABOLMASOUMI, H. R., MOMENI, This paper is concerned with the problem of TCP congestion control for the class of communication networks with random parameters. The linear dynamic model of TCP New Reno in congestion avoidance mode is considered which contains round trip delays in both state and input. The randomness of link capacity, round trip time delay and the number of TCP sessions is modeled with a continuous-time finite state Markov process. An Active Queue Management (AQM) technique is then used to adjust the queue level of the congested link to a predefined value. For this purpose, a dynamic output feedback controller with mode dependent parameters is synthesized to stochastically stabilize the TCP/AQM dynamics. The procedure of the control synthesis is implemented by solving a linear matrix inequality (LMI). The results are tested within a simulation example and the effectiveness of the proposed design method is verified. Mon, 30 May 2011 00:00:00 +0300 http://dx.doi.org/10.4316/aece.2011.02012 http://dx.doi.org/10.4316/aece.2011.02012 R., MUNTEANU, V., DUB, The robustness of power grids characterizes the behavior of grids in situations of serial failures and/or human errors. A coherent method of evaluating vulnerability is to quantify this attribute in terms of the scale-free graph theory. One way of increasing power grid robustness consists of adding new electric lines between the existing nodes. Once the target scale-free network is found, the real network must be enlarged to the graph of the target network. The choice of a reasonable solution is made difficult by the great number of topological solutions, because this number increases as the number of the network nodes becomes bigger. Thus, the first aim is to make an inventory of all these solutions. The second necessary step is to build correct algorithms able to find the nodes of the real grid which will be connected respecting economical criteria. In continuation of our previous research, our paper proposes a Petri net-based method of building all enlargement variants, starting from non-robust networks to the nearest free-scale, robust network. Starting from some distinctive characteristics of elementary enlargements introduced in our earlier works, this allows us to obtain a mathematically unique, robustness-oriented enlargement solution. Mon, 30 May 2011 00:00:00 +0300 http://dx.doi.org/10.4316/aece.2011.02013 http://dx.doi.org/10.4316/aece.2011.02013 A. M., HADDADI, A., KAZEMI, This paper presents a new power flow model for rotary power flow controller (RPFC). RPFC injects a series voltage into the transmission line and provides series compensation and phase shifting simultaneously. Therefore, it is able to control the transmission line impedance and the active power flow through it. An RPFC is composed mainly of two rotary phase shifting transformers (RPST) and two conventional (series and shunt) transformers. Structurally, an RPST consists of two windings (stator and rotor windings). The rotor windings of the two RPSTs are connected in parallel and their stator windings are in series. The injected voltage is proportional to the vector sum of the stator voltages and so its amplitude and angle are affected by the rotor position of the two RPSTs. This paper, describes the steady state operation and single-phase equivalent circuit of the RPFC. Also in this paper, a new power flow model, based on power injection model of flexible ac transmission system (FACTS) controllers, suitable for the power flow analysis is introduced. Proposed model is used to solve optimal power flow (OPF) problem in IEEE standard test systems incorporating RPFC and the optimal settings and location of the RPFC is determined. Mon, 30 May 2011 00:00:00 +0300 http://dx.doi.org/10.4316/aece.2011.02014 http://dx.doi.org/10.4316/aece.2011.02014 P., WISUTMETHEEKORN, V., CHUNKAG, This paper presents a digital signal processor based control of an AC/DC converter with nearly unity power factor. Normally, the output voltage of a single-phase AC/DC converter comprises a voltage ripple with twice line-frequency. This affects the voltage control loop and leads to the converter input current distortion. The purposed method is designed to avoid the effect of the output voltage ripple. To verify the proposed control method, MATLAB/Simulink is used for system simulation. A hardware prototype is setup. A low cost digital signal processing chip dsPIC30F4011 is employed as a digital controller to control a CUK AC/DC converter. The converter specifications are 48V output voltage and 250W output power. From the simulation and the experimental results shown that the input current distortion of the purposed system is reduced and lower than the AC/DC converter that controlled by the conventional proportional-integral controller. Mon, 30 May 2011 00:00:00 +0300 http://dx.doi.org/10.4316/aece.2011.02015 http://dx.doi.org/10.4316/aece.2011.02015 C. K., AHN, This paper investigates the passivity based filtering problem for multilayer Hopfield neural networks with external disturbance. A new passivity based filter design method for multilayer Hopfield neural networks is developed to ensure that the filtering error system is exponentially stable and passive from the external disturbance vector to the output error vector. The unknown gain matrix is obtained by solving a linear matrix inequality (LMI), which can be easily facilitated by using some standard numerical packages. An illustrative example is given to demonstrate the effectiveness of the proposed filter. Mon, 30 May 2011 00:00:00 +0300 http://dx.doi.org/10.4316/aece.2011.02016 http://dx.doi.org/10.4316/aece.2011.02016 S. M. H., NABAVI, A., KAZEMI, M. A. S., MASOUM, This paper presents a genetic algorithm (GA) to maximize total system social welfare and alleviate congestion by best placement and sizing of TCSC device, in a double-sided auction market. To introduce more accurate modeling, the valve loading effects is incorporated to the conventional quadratic smooth generator cost curves. By adding the valve point effect, the model presents nondifferentiable and nonconvex regions that challenge most gradient-based optimization algorithms. In addition, quadratic consumer benefit functions integrated in the objective function to guarantee that locational marginal prices charged at the demand buses is less than or equal to DisCos benefit, earned by selling that power to retail customers. The proposed approach makes use of the genetic algorithm to optimal schedule GenCos, DisCos and TCSC location and size, while the Newton-Raphson algorithm minimizes the mismatch of the power flow equations. Simulation results on the modified IEEE 14-bus and 30-bus test systems (with/without line flow constraints, before and after the compensation) are used to examine the impact of TCSC on the total system social welfare improvement. Several cases are considered to test and validate the consistency of detecting best solutions. Simulation results are compared to solutions obtained by sequential quadratic programming (SQP) approaches. Mon, 30 May 2011 00:00:00 +0300 http://dx.doi.org/10.4316/aece.2011.02017 http://dx.doi.org/10.4316/aece.2011.02017 A., TAHERI, A., RAHMATI, S., KABOLI, This paper deals with the efficiency optimization of Field Oriented Control (FOC) of a six-Phase Induction Motor (6PIM) by adaptive flux search control. The six-phase induction motor is supplied by Space Vector PWM (SVPWM) and voltage source inverter. Adaptive flux search controller is fast than ordinary search control technique and easy to implement. Adaptive flux Search Control (SC) technique decreases the convergence time by proper change of flux variation steps and increases accuracy of the SC technique. A proper loss model of 6PIM in conjunction with the proposed method is used. The six-phase induction machine has large zero sequence harmonic currents that can be reduced by SVPWM technique. Simulation and experimental results are carried out and they verify the effectiveness of the proposed approach. Mon, 30 May 2011 00:00:00 +0300 http://dx.doi.org/10.4316/aece.2011.02018 http://dx.doi.org/10.4316/aece.2011.02018 S., MIHAI, A., SIMION, L., LIVADARU, A., MUNTEANU, This paper presents a study of an induction motor provided with toroidal stator winding. The ring-type coils offer a higher versatility in obtaining a different number of pole pairs by means of delta/star and series/parallel connections respectively. As consequence, the developed torque can vary within large limits and the motor can be utilized for applications that require, for example, high load torque values for a short time. The study involves experimental tests and FEM simulation for an induction machine with three configurations of pole pairs. The conclusions attest the superiority of the toroidal winding for certain applications such as electric vehicles or lifting machines. Mon, 30 May 2011 00:00:00 +0300 http://dx.doi.org/10.4316/aece.2011.02019 http://dx.doi.org/10.4316/aece.2011.02019 L., FAN, Y., YU, DC-DC converters have some inherent characteristics such as high nonlinearity and time-variation, which often result in some difficulties in designing control schemes. An adaptive non-singular terminal sliding mode control method is presented in this paper. Non-singular terminal sliding mode control is used to make the converter reach steady state within a limited time, and an adaptive law is integrated to the non-singular terminal sliding mode control scheme to make the proposed control method have adaptive ability to disturbances, and overcome the limitation on non-singular terminal sliding mode control scheme caused by disturbance boundary value. Simulation results show the validity of this adaptive non-singular terminal sliding mode control approach. Mon, 30 May 2011 00:00:00 +0300 http://dx.doi.org/10.4316/aece.2011.02020 http://dx.doi.org/10.4316/aece.2011.02020 M. G., DANIKAS, A. D., KARLIS, Partial discharges (PD) contribute greatly to the ageing and the breakdown of solid insulating materials. In the present paper, some conductivity measurements are performed relating the conductivity of inner walls of an enclosed cavity to the behaviour of PD in the case of polyethylene and of epoxy resin. The temporary decrease of the PD magnitude is explained in terms of the increase of the cavity inner wall conductivity. The PD behaviour is studied in epoxy resin samples and is explained with the aid of Pedersen's model. Scanning Electron Microscope (SEM) photographs indicate the sort of damage suffered by the cavity walls under electrical stress. Mon, 30 May 2011 00:00:00 +0300 http://dx.doi.org/10.4316/aece.2011.02021 http://dx.doi.org/10.4316/aece.2011.02021 M. R., BESMI, M. E., MOSLEH, This paper presents a new method to calculate stray capacitance between conductor wire filaments. The new proposed method is called vespiary regular hexagonal (VRH) model. In this paper conductor of magneto cumulative generator (MCG) coil has a multilayer wire. So the proposed model is used to calculate stray capacitance between two adjacent wire filaments (WFs) and capacitance between the wire filaments and central cylindrical liner in one turn of coil (OTC). The presented method in this paper is based on an analytical method and geometrical structure. In one turn of coil, the wire filaments in VRH method are separated into many very small similar elementary cells. In this structure, an equilateral lozenge-shape basic cell (ELBC) with two trapezium-shape regions has been considered between two adjacent wire filaments. This method is applied to calculate the total stray capacitance of N-turns of coil (NTC) with multi WFs in round cross-section. Simulation results show that the proposed method is very useful for designing a geometrical structure of the MCG coil. Mon, 30 May 2011 00:00:00 +0300 http://dx.doi.org/10.4316/aece.2011.03001 http://dx.doi.org/10.4316/aece.2011.03001 I. S., MOSKOWITZ, P., COTAE, M. H., KANG, P. N., SAFIER, In this paper, we derive closed form approximations for the capacity of a point-to-point, deterministic Gaussian MIMO communication channel. We focus on the behavior of the inverse eigenvalues of the Gram matrix associated with the gain matrix of the MIMO channel, by considering small variance and large power assumptions. We revisit the concept of deterministic MIMO capacity by pointing out that, under transmitter power constraint, the optimal transmit covariance matrix is not necessarily diagonal. We discuss the water filling algorithm for obtaining the optimal eigenvalues of the transmitter covariance matrix, and the water fill level in conjunction with the Karush-Kuhn-Tucker optimality conditions. We revise the Telatar conjecture for the capacity of a non-ergodic channel. We also provide deterministic examples and numerical simulations of the capacity, which are discussed in terms of our mathematical framework. Wed, 31 Aug 2011 00:00:00 +0300 http://dx.doi.org/10.4316/aece.2011.03002 http://dx.doi.org/10.4316/aece.2011.03002 J., DUAN, Y., LI, Spectrum handoff procedures occur when the primary users appear in the licensed band temporary occupied by the cognitive radio (CR) users and aim to help the CR users to vacate the spectrum rapidly and find available channel to resume the transmission. However, a spectrum handoff scheme that comprehensively considers channel selection, handoff decision as well as space domain handoff is yet undeveloped. In this paper we present a complete optimal spectrum handoff scheme for cognitive radio mobile ad hoc networks. First, we design a spectrum selection mechanism to allow CR users optimally choose the appropriate channel. The spectrum idleness prediction algorithm is utilized based on developing a cooperative spectrum searching approach. Through combining the estimated transmission time, the PU appearance probability and the mean spectrum availability time are integrated to develop the optimal spectrum handoff scheme. Moreover, as one part of the proposed scheme, a geo-location approach is utilized to deal with the space domain handoff. The complete scheme is evaluated through a comprehensive simulation study, and results reveal significant improvements in handoff times and transmission efficiency over conventional approaches. Wed, 31 Aug 2011 00:00:00 +0300 http://dx.doi.org/10.4316/aece.2011.03003 http://dx.doi.org/10.4316/aece.2011.03003 M., MERAH, A., OUAMRI, A., NAIT-ALI, M., KECHE, The aim of this paper is to apply a new robust hardware Artificial Neural Network (ANN) for ECG classification systems. This ANN includes a penalization criterion which makes the performances in terms of robustness. Specifically, in this method, the ANN weights are normalized using the auto-prune method. Simulations performed on the MIT - BIH ECG signals, have shown that significant robustness improvements are obtained regarding potential hardware artificial neuron failures. Moreover, we show that the proposed design achieves better generalization performances, compared to the standard back-propagation algorithm. Wed, 31 Aug 2011 00:00:00 +0300 http://dx.doi.org/10.4316/aece.2011.03004 http://dx.doi.org/10.4316/aece.2011.03004 H., MOTTE, J., WYFFELS, L., DE STRYCKER, J.-P., GOEMAERE, With the latest generation of ultra-sensitive GPS-receivers, satellite signals can often be picked up even indoors, resulting in (inaccurate) indoor GPS-localization. A covered position will therefore no longer be characterized by the absence of satellite signals, creating the need for another way of categorizing this data as potentially inaccurate. This paper describes the use of GPS-based localization in an indoor environment. Only high level, generally available, GPS-data (NMEA-0183 GNSS-subset) are taken into account. Applications of ubiquitous location awareness, where the use of several RTLS (Real Time Location System) combinations is feasible, may benefit from this information to discriminate between GPS and other available localization data. A quality indicating parameter is readily available in GPS-data; the DOP (Dilution Of Precision) data field, which indicates the accuracy of the GPS localization based on the current satellite geometry. However since in indoor environments the roof and possible overlying floors often cause more signal attenuation compared to (outer) walls or windows, the probability of a better reception of 'low' orbiting satellite signals increases, giving rise to an unjustified good horizontal DOP value. Standard NMEA-0183 GPS strings are therefore analyzed in search of other indicators for malicious GPS-data. Wed, 31 Aug 2011 00:00:00 +0300 http://dx.doi.org/10.4316/aece.2011.03005 http://dx.doi.org/10.4316/aece.2011.03005 J. M., KNEZEVIC, V. A., KATIC, The novel hybrid method of the Discrete Fourier Transform (DFT) and the Enhanced Phase-Locked Loop (EPLL) has been presented. The original well-known methods and the Hybrid method have been analysed and tested in several simulations and experiments. The methods are implemented on the Digital Signal Processor and compared in a real time power quality application. Although it requires a bit higher computational effort, the Hybrid method compared to original methods shows advantages for on-line harmonic analysis. Wed, 31 Aug 2011 00:00:00 +0300 http://dx.doi.org/10.4316/aece.2011.03006 http://dx.doi.org/10.4316/aece.2011.03006 H.-W., LEE, M.-Y., JEON, This paper proposes an adaptive algorithm for the combined acoustic feedback and noise cancellation in the binaural hearing aids. The proposed algorithm is based on dual microphones for feedback cancellation and the beamforming method for noise cancellation. The coefficients of feedback canceller are updated after subtracting the speech signal from the input signal by dual microphones. And the noise canceller reduces the noise signal in the residual signal excluding the speech by the beamforming method. Firstly, the feedback canceller operates to cancel the feedback signal in the microphone signal, and then the noise canceller operates to reduce the noise in the residual signal. Also, to assure the stable convergence of binaural hearing aids in the training mode, the coefficients of the left hearing aid are firstly updated, then the coefficients of the right hearing aid are updated. In the normal mode, the feedback and the noise canceller are operated without updating coefficients except an unstable case. To verify performances of the proposed algorithm, we analyzed its convergence behavior and simulated for real speech. From the results of simulations, it was proved that we can advance 14.43dB SFR(speech-to-feedback ratio) on average in the feedback canceller, 10.19dB SNR(speech-to-noise ratio) improvement on average in the noise canceller, in the case of applying the proposed algorithm. Wed, 31 Aug 2011 00:00:00 +0300 http://dx.doi.org/10.4316/aece.2011.03007 http://dx.doi.org/10.4316/aece.2011.03007 O., GRIGORE, V., VELICAN, This paper presents a method of identifying heavily impaired pronunciations of 'r' consonant in Romanian language using Kohonen neural networks. The study focused on words that contain 'r' as the first letter and used signals recorded mainly from children, as mispronunciations occur most of the time at young age persons. Parameters of the alternating component of each speech sample's envelope are used as feature vectors in the classification stage. Wed, 31 Aug 2011 00:00:00 +0300 http://dx.doi.org/10.4316/aece.2011.03008 http://dx.doi.org/10.4316/aece.2011.03008 N., SKOBERNE, M., CIGLARIC, It is often suggested that the approach to IPv6 transition is dual-stack deployment; however, it is not feasible in certain environments. As Network Address Translation -- Protocol Translation (NAT-PT) has been deprecated, stateful NAT64 and DNS64 RFCs have been published, supporting only IPv6-to-IPv4 translation scenario. Now the question of usability in the real world arises. In this paper, we systematically test a number of widely used application-layer network protocols to find out how well they traverse Ecdysis, the first open source stateful NAT64 and DNS64 implementation. We practically evaluated 18 popular protocols, among them HTTP, RDP, MSNP, and IMAP, and discuss the shortcomings of such translations that might not be apparent at first sight. Wed, 31 Aug 2011 00:00:00 +0300 http://dx.doi.org/10.4316/aece.2011.03009 http://dx.doi.org/10.4316/aece.2011.03009 H., SU, Q., LIU, J., LI, Border effects are very common in many finite signals analysis and processing approaches using convolution operation. Alleviating the border effects that can occur in the processing of finite-length signals using wavelet transform is considered in this paper. Traditional methods for alleviating the border effects are suitable to compression or coding applications. We propose an algorithm based on Fourier series which is proved to be appropriate to the application of time-frequency analysis of nonlinear signals. Fourier series extension method preserves the time-varying characteristics of the signals. A modified signal duration expression for measuring the extent of border effects region is presented. The proposed algorithm is confirmed to be efficient to alleviate the border effects in comparison to the current methods through the numerical examples. Wed, 31 Aug 2011 00:00:00 +0300 http://dx.doi.org/10.4316/aece.2011.03010 http://dx.doi.org/10.4316/aece.2011.03010 V., DESPOTOVIC, Z., PERIC, Adaptive differential pulse code modulation (ADPCM) with forward gain-adaptive quantizer and second-order switched predictor based on correlation is presented in this article. Predictor consists of a bank of predetermined predictors for each block of speech samples, avoiding the need to solve, or quantize predictor coefficients during the coding process. The adaptation consists of switching to one of this predictors based on the values of the first and second order correlation coefficients. The theoretical model is generalization of the DPCM with the first order switched predictor for an arbitrary prediction order. Experimental results for ADPCM with the second-order four/eight state switched prediction based on correlation are provided. Wed, 31 Aug 2011 00:00:00 +0300 http://dx.doi.org/10.4316/aece.2011.03011 http://dx.doi.org/10.4316/aece.2011.03011 T., TUDORACHE, V., BOSTAN, This paper proposes a novel and robust strategy for the optimal design of the drive system integrated in a wind generators test bench. The PI regulator coefficients used in control systems are usually computed based on simplified hypotheses and then tuned manually so as the system response meet certain specifications in terms of stability, accuracy and speed. The proposed methodology permits the automatic identification of PI regulator coefficients using intelligent optimization algorithms, the initial guess for the search procedure being determined based on particular simplified hypotheses. The proposed procedure can help the design engineers to drastically reduce the effort for finding the best PI regulator coefficients offering a range of feasible solutions depending on the imposed optimum criteria. The characteristics and performances of the optimization strategy are highlighted by using it for the design of a DC motor drive system used to simulate the wind prime mover integrated in a wind generators test bench. Wed, 31 Aug 2011 00:00:00 +0300 http://dx.doi.org/10.4316/aece.2011.03012 http://dx.doi.org/10.4316/aece.2011.03012 B. M., MUTHU, R., VEILUMUTHU, L., PONNUSAMY, The modern power systems consist of many interconnected synchronous generators having different inertia constants, connected with large transmission network and ever increasing demand for power exchange. The size of the power system grows exponentially due to increase in power demand. The data required for various power system applications have been stored in different formats in a heterogeneous environment. The power system applications themselves have been developed and deployed in different platforms and language paradigms. Interoperability between power system applications becomes a major issue because of the heterogeneous nature. The main aim of the paper is to develop a generalized distributed model for carrying out power system stability analysis. The more flexible and loosely coupled JAX-RPC model has been developed for representing transient stability analysis in large interconnected power systems. The proposed model includes Pre-Fault, During-Fault, Post-Fault and Swing Curve services which are accessible to the remote power system clients when the system is subjected to large disturbances. A generalized XML based model for data representation has also been proposed for exchanging data in order to enhance the interoperability between legacy power system applications. The performance measure, Round Trip Time (RTT) is estimated for different power systems using the proposed JAX-RPC model and compared with the results obtained using traditional client-server and Java RMI models. Wed, 31 Aug 2011 00:00:00 +0300 http://dx.doi.org/10.4316/aece.2011.03013 http://dx.doi.org/10.4316/aece.2011.03013 A., SADR, A. K., MOMTAZ, Clustering is one of the most important research topics which has many practical applications such as medical imaging and Non-Destructive Testing (NDT). Most clustering algorithms like K-means, fuzzy C-Means (FCM) and their derivatives require the number of clusters as one of the initializing parameters. This paper proposes an algorithm for image clustering with no need to any initializing parameter. In this state-of-the-art, an image is sampled based on a rosette pattern and according to the pattern characteristics, the extracted samples are clustered and then the number of clusters is determined. The centroids of classes are computed by means of a method based on calculation of distribution function. Based on different data sets, the results show that the algorithm improves the capability of the clustering by a minimum of 62.26% and 87.62% in comparison with FCM and K-means algorithms, respectively. Moreover, in dealing with high resolution data sets, the efficiency of the algorithm in clusters detection and run time improvement increases considerably. Wed, 31 Aug 2011 00:00:00 +0300 http://dx.doi.org/10.4316/aece.2011.03014 http://dx.doi.org/10.4316/aece.2011.03014 J., LEE, J., NANG, Recently the method of specifying multiple regions of interest (ROI) based image retrieval has been suggested. However it measures the similarity of the images without proper consideration of the spatial layouts of the ROIs and thus fails to accurately reflect the intent of the user. In this paper, we propose a new similarity measurement using the relative layouts of the ROIs. The proposed method divides images into blocks of certain size and extracted MPEG-7 dominant colors from the blocks overlapping with the user-designated ROIs to measure their similarities with the target images. At this point, similarity was weighted when the relative location of the ROIs in the query image and the target image was the same. The relative location was calculated by four directions (i.e. up, down, left and right) of the basis ROI. The proposed method by an experiment using MPEG-7 XM shows that its performance is higher than the global image retrieval method or the retrieval method that does not consider the relative location of ROIs. Wed, 31 Aug 2011 00:00:00 +0300 http://dx.doi.org/10.4316/aece.2011.03015 http://dx.doi.org/10.4316/aece.2011.03015 C.-T., CHANG, J. Z. C., LAI, M.-D., JENG, In this paper, we present a codebook generation algorithm to produce a codebook with lower distortion. Our method combines a fast codebook generation algorithm (CGAUCD) with doubling technique and fast agglomerative clustering algorithm (FACA) to generate a codebook with less computing time and lower distortion. Instead of using FACA directly to divide training vectors into M clusters, our proposed method first generates qM clusters from these training vectors, where q>1 is an integer, and then applies FACA to merge these qM clusters into M cells. This is due to the computational complexity of CGAUCD with doubling technique is less than that of FACA. These M cluster centers are used as the initial codebook for CGAUCD. Using three real images as the training set, our method can reduce the MSE and computing time of FPNN+CGAUCD, which is the available best method to our knowledge, by 0.19 to 0.38 and 74.6% to 84.3%, respectively. Wed, 31 Aug 2011 00:00:00 +0300 http://dx.doi.org/10.4316/aece.2011.03016 http://dx.doi.org/10.4316/aece.2011.03016 P., HERGHELEGIU, M., GAVRILESCU, V., MANTA, The simultaneous inspection of images obtained using different medical scanning methods represents a common practice for accurate medical diagnosis. The term multimodality refers to multiple medical data sets obtained by scanning a patient with the same method at different time moments or with different scanning techniques. Recent research efforts in computer graphics have attempted to solve the problem of visualizing multimodal data in the same scene, for a better understanding of human anatomy or for pathology tracking. This paper proposes a method of integrating segmented structures from a contrast enhanced MRI sequence into the volume reconstructed from the slices of another MRI sequence obtained with different scanning parameters. A direct volume rendering (DVR) approach is used to represent focus and context information from the 3D data. The presented approach aims to help physicians in understanding pathologies and in the process of accurate diagnosis establishment. Wed, 31 Aug 2011 00:00:00 +0300 http://dx.doi.org/10.4316/aece.2011.03017 http://dx.doi.org/10.4316/aece.2011.03017 D.-M., POPOVICI, C.-M., BOGDAN, M., POLCEANU, R., QUERREC, Any virtual environment (VE) built in a classical way is dedicated to a very specific domain. Its modification or even adaptation to another domain requires an expensive human intervention measured in time and money. This way, the product, that means the VE, returns at the first phases of the development process. In a previous work we proposed an approach that combines domain ontologies and conceptual modeling to construct more accurate VEs. Our method is based on the description of the domain knowledge in a standard format and the assisted creation (using these pieces of knowledge) of the VE. This permits the explanation within the virtual reality (VR) simulation of the semantic of the whole context and of each object. This knowledge may be then transferred to the public users. In this paper we prove the effectiveness of our method on the construction process of an VE that simulates the organization of a Greek-Roman colony situated on the Black Sea coast and the economic and social activities of its people. Wed, 31 Aug 2011 00:00:00 +0300 http://dx.doi.org/10.4316/aece.2011.03018 http://dx.doi.org/10.4316/aece.2011.03018 A., BARLEANU, V., BAITOIU, A., STAN, A method for transforming C code with floating-point values into C code with integer variables is developed. The objective is to avoid any operations with floating-point data types, thereby increasing the execution speed of the program on a microprocessor without a math coprocessor. The original C code must be a dot product with floating-point literals and integer variables with known interval bounds. The transformation algorithm remodels the dot product form into a tree structure, to maximize the accuracy, but, on the other side, keeps the number of shift operations reduced. The integer code that is generated is ANSI C compliant. It is tested on 8-bit and 32-bit microprocessors using different compilers. The results show that the integer code is several times faster than the floating-point code, the only loss being a very low accuracy drop. Wed, 31 Aug 2011 00:00:00 +0300 http://dx.doi.org/10.4316/aece.2011.03019 http://dx.doi.org/10.4316/aece.2011.03019 S., HOSSEINI, J. S., MOGHANI, B. B., JENSEN, This paper presents an accurate modeling method that is applied to a single-sided outer-rotor transverse flux permanent magnet generator. The inductances and the induced electromotive force for a typical generator are calculated using the magnetostatic three-dimensional finite element method. A new method is then proposed that reveals the behavior of the generator under any load. Finally, torque calculations are carried out using three dimensional finite element analyses. It is shown that although in the single-phase generator the cogging torque is very high, this can be improved significantly by combining three single-phase modules into a three-phase generator. Wed, 31 Aug 2011 00:00:00 +0300 http://dx.doi.org/10.4316/aece.2011.04001 http://dx.doi.org/10.4316/aece.2011.04001 G. J., JANG, J. S., PARK, J. H., KIM, Y. H., SEO, This paper proposes a noise suppression technique for speech-centric interface of various smart devices. The proposed method estimates noise spectral magnitudes from line spectral frequencies (LSFs), using the observation that adjacent LSFs correspond to peak frequencies of spectrum, whereas isolated LSFs are close to flattened valley frequencies retaining noise components. Over a course of segmented time frames, the logarithms of spectral magnitudes at respective LSFs are computed, and their distribution is then modeled by the Rayleigh probability density function. The standard deviation from the Rayleigh function approximates the noise spectral magnitude. The model is updated at every frame in an online manner so that it can deal with real-time inputs. Once the noise spectral magnitude is estimated, a time-domain Wiener filter is derived for the suppression of the estimated noise spectral magnitude, and this is then applied to the input noisy speech signals. Our proposed approach operates well on most smart devices owing to its low computational complexity and real-time implementation. Speech recognition experiments, conducted to evaluate the proposed technique, show that our method exhibits superior performance, with less distortion of original speech, when compared to conventional noise suppression techniques. Wed, 30 Nov 2011 00:00:00 +0200 http://dx.doi.org/10.4316/aece.2011.04002 http://dx.doi.org/10.4316/aece.2011.04002 A., MALANCIUC, A., SIMION, L., LIVADARU, A., MUNTEANU, C., AFANASOV, The paper presents a simulation study of a hybrid synchronous generator (dual excitation system - permanent magnets and electromagnets) with skewed stator slots. The main goal is to establish if the skewing of the slots brings a significant improvement of the air-gap flux density and of the induced stator voltage. The skewness angle is the parameter in discussion. The study is based on finite element method analysis. Due to the particular geometry of the stator slots, a multilayer approach is employed. Wed, 30 Nov 2011 00:00:00 +0200 http://dx.doi.org/10.4316/aece.2011.04003 http://dx.doi.org/10.4316/aece.2011.04003 D., RISTIC-DURRANT, S. M., GRIGORESCU, A., GRASER, Z., COJBASIC, V., NIKOLIC, A key requirement of assistive robot vision is the robust 3D object reconstruction in complex environments for reliable autonomous object manipulation. In this paper the idea is presented of achieving high robustness of a complete robot vision system against external influences such as variable illumination by including feedback control of the object segmentation in stereo images. The approach used is to change the segmentation parameters in closed-loop so that object features extraction is driven to a desired result. Reliable feature extraction is necessary to fully exploit a neuro-fuzzy classifier which is the core of the proposed 2D object recognition method, predecessor of 3D object reconstruction. Experimental results on the rehabilitation assistive robotic system FRIEND demonstrate the effectiveness of the proposed method. Wed, 30 Nov 2011 00:00:00 +0200 http://dx.doi.org/10.4316/aece.2011.04004 http://dx.doi.org/10.4316/aece.2011.04004 V. A., MARABA, A. E., KUZUCUOGLU, This paper deals with the structure and characteristics of PID Neural Network controller for single input and single output systems. PID Neural Network is a new kind of controller that includes the advantages of artificial neural networks and classic PID controller. Functioning of this controller is based on the update of controller parameters according to the value extracted from system output pursuant to the rules of back propagation algorithm used in artificial neural networks. Parameters obtained from the application of PID Neural Network training algorithm on the speed model of the asynchronous motor exhibiting second order linear behavior were used in the real time speed control of the motor. Programmable logic controller (PLC) was used as real time controller. The real time control results show that reference speed successfully maintained under various load conditions. Wed, 30 Nov 2011 00:00:00 +0200 http://dx.doi.org/10.4316/aece.2011.04005 http://dx.doi.org/10.4316/aece.2011.04005 L., TIGAERU, G., BONTEANU, We propose a neuron model, able to reproduce the basic elements of the neuronal dynamics, optimized for digital implementation of Spiking Neural Networks. Its architecture is structured in two major blocks, a datapath and a control unit. The datapath consists of a membrane potential circuit, which emulates the neuronal dynamics at the soma level, and a synaptic circuit used to update the synaptic weight according to the spike timing dependent plasticity (STDP) mechanism. The proposed model is implemented into a Cyclone II-Altera FPGA device. Our results indicate the neuron model can be used to build up 1K Spiking Neural Networks on reconfigurable logic suport, to explore various network topologies. Wed, 30 Nov 2011 00:00:00 +0200 http://dx.doi.org/10.4316/aece.2011.04006 http://dx.doi.org/10.4316/aece.2011.04006 Z., PERIC, J., NIKOLIC, In this paper, the design procedure of the piecewise uniform scalar quantizer having segments with widths that form a geometric progression is presented. The proposed quantizer design optimization for the Laplacian source of the unit variance is performed by optimizing the distortion in respect to the support region threshold and the scaling factor which defines the geometric progression of the consecutive segment widths. For the proposed quantizer model and its forward adaptive version, the signal to quantization noise ratio robustness analysis in a wide variance range is also presented in the paper. Regarding the performance comparision of the proposed quantizer, the uniform quantizer and the G.711 quantizer, the conclusion of the proposed quantizer significance is distinctly shown in the paper. Wed, 30 Nov 2011 00:00:00 +0200 http://dx.doi.org/10.4316/aece.2011.04007 http://dx.doi.org/10.4316/aece.2011.04007 D., CAPKO, A., ERDELJAN, M., POPOVIC, G., SVENDA, Modern Utility Management Systems which utilize multiprocessor systems for efficient processing of large data model are considered in this paper. The necessary preconditions for the efficient calculation are optimal load balancing of processors and data model partitioning among processors. The novel multilevel Super-Roots (SR) algorithm was developed to improve existing algorithms (e. i. METIS) for initial partitioning of data model. The proposed algorithms are applied on data model describing large electricity power distribution network. Experiments show that SR algorithm achieves better results than METIS multilevel algorithm in many cases. Wed, 30 Nov 2011 00:00:00 +0200 http://dx.doi.org/10.4316/aece.2011.04008 http://dx.doi.org/10.4316/aece.2011.04008 M., KUPIMAI, A., MEESOMBOON, V., IMTAWIL, High rate irregular QC-LDPC codes based on circulant permutation matrices, for efficient encoder implementation, are proposed in this article. The structure of the code is an approximate lower triangular matrix. In addition, we present two novel efficient encoding techniques for generating redundant bits. The complexity of the encoder implementation depends on the number of parity bits of the code for the one-stage encoding and the length of the code for the two-stage encoding. The advantage of both encoding techniques is that few XOR-gates are used in the encoder implementation. Simulation results on partial response channels also show that the BER performance of the proposed code has gain over other QC-LDPC codes. Wed, 30 Nov 2011 00:00:00 +0200 http://dx.doi.org/10.4316/aece.2011.04009 http://dx.doi.org/10.4316/aece.2011.04009 L., FLOREA, C., FLOREA, C., VERTAN, A., SULTANA, Total hip replacement is a common procedure in today orthopedics, with high rate of long-term success. Failure prevention is based on a regular follow-up aimed at checking the prosthesis fit and state by means of visual inspection of radiographic images. It is our purpose to provide automatic means for aiding medical personnel in this task. Therefore we have constructed tools for automatic identification of the component parts of the radiograph, followed by analysis of interactions between the bone and the prosthesis. The results form a set of parameters with obvious interest in medical diagnosis. Wed, 30 Nov 2011 00:00:00 +0200 http://dx.doi.org/10.4316/aece.2011.04010 http://dx.doi.org/10.4316/aece.2011.04010 S., MUSSI, The intended meaning of the term predictive monitoring used in the paper is the following. A population of subjects (living beings, machines, works of art, etc.) is monitored by a domain expert with regard to the possible occurrence of an undesired/desired event E. More precisely, an expert periodically (e.g. every two years, every week, etc. depending on the specific application) examines the single subjects and, for each of them, enters examination outcomes in a database where statistical data are automatically processed in order to produce probabilistic inferences about the occurrence in the future of E for the subject under examination (individualized prediction). This allows the expert to take suitable measures in advance in order to prevent/favour the occurrence of E for the subject. Such an approach to predictive monitoring requires that the expert who monitors subjects has at his/her disposal a suitable software system provided with database and algorithms for both properly managing monitoring-processes and producing probabilistic predictions. The paper presents CHEERUP : a prototype product, usable via Internet, that consists in a general software-environment for building, using and administering specific predictive monitoring software-systems (in the paper called portals). Wed, 30 Nov 2011 00:00:00 +0200 http://dx.doi.org/10.4316/aece.2011.04011 http://dx.doi.org/10.4316/aece.2011.04011 Z., IRKI, M., DEVY, In this paper, we present an approach which makes uses of precalculated tables in order to carry out a real time image processing task. This approach is very useful when the relation between the input image and the output image (after treatment) is given in the backward direction (the input image is expressed using the output image). We illustrate this approach in the case of the rotation of an image around its center. We illustrate how theses precalculated tables should be built and the influence of some parameters on the size of theme. By the end, we discuss how this approach could be implemented on a reconfigurable hardware as an FPGA. Wed, 30 Nov 2011 00:00:00 +0200 http://dx.doi.org/10.4316/aece.2011.04012 http://dx.doi.org/10.4316/aece.2011.04012 T., TUDORACHE, M., POPESCU, This paper presents optimal design solutions for reducing the cogging torque of permanent magnets synchronous machines. A first solution proposed in the paper consists in using closed stator slots that determines a nearly isotropic magnetic structure of the stator core, reducing the mutual attraction between permanent magnets and the slotted armature. To avoid complications in the windings manufacture technology the stator slots are closed using wedges made of soft magnetic composite materials. The second solution consists in properly choosing the combination of pole number and stator slots number that typically leads to a winding with fractional number of slots/pole/phase. The proposed measures for cogging torque reduction are analyzed by means of 2D/3D finite element models developed using the professional Flux software package. Numerical results are discussed and compared with experimental ones obtained by testing a PMSM prototype. Wed, 30 Nov 2011 00:00:00 +0200 http://dx.doi.org/10.4316/aece.2011.04013 http://dx.doi.org/10.4316/aece.2011.04013 K., ZAPLATILEK, J., LEUCHTER, This article deals with creation and application of a model of photovoltaic panel in the MATLAB and Simulink environments. An original model of the real PV panel is applied using the model based design technique. A so-called physical model is also developed using the SimPowerSystems library. The described PV panel model is applied for maximum power optimization in the one-shot and the continuous modes. A few illustrating examples and source code parts are also presented. Wed, 30 Nov 2011 00:00:00 +0200 http://dx.doi.org/10.4316/aece.2011.04014 http://dx.doi.org/10.4316/aece.2011.04014 C., NEMES, F., MUNTEANU, The sun is an extremely powerful energy source and solar radiation is by far the largest source of energy received by the earth. Assessment of solar radiation can be based upon measured data, where are available, or results of mathematical models. In this paper is presented a model, developed on the clear sky conditions, which allows calculation of solar radiation intensity at any location on the earth surface, considering the geographical coordinates of location and local time of every day of the year. Based on the SRTM database, in the paper it is developed a digital elevation model, which together with presented model allows computation of the potential of solar radiation over the Iasi county territory. For validation, the results have been compared with data obtained from SoDa project, the results from both database being fairly close, these proving satisfactory accuracy for a preliminary evaluation of solar radiation. Wed, 30 Nov 2011 00:00:00 +0200 http://dx.doi.org/10.4316/aece.2011.04015 http://dx.doi.org/10.4316/aece.2011.04015 C., MOREL, D., PETREUS, A., RUSU, This paper describes bifurcation phenomena of a photovoltaic system. The studied photovoltaic (PV) system includes a solar panel, a boost converter, a maximum power point tracking (MPPT) controller and a storage device. Computer simulations are performed to capture the effects of variation of some chosen parameters on the qualitative behavior of the system. The impact of the maximum power point (MPP) current and voltage variations due to luminosity changes is determinate, as well as the load variation. The stability of the system is analyzed using the state transition matrix over one switching cycle (the monodromy matrix) including the state transition matrices during each switching (the saltation matrices). This investigation is important to predict nonlinear phenomena and for the components dimensioning for a proper functioning. Wed, 30 Nov 2011 00:00:00 +0200 http://dx.doi.org/10.4316/aece.2011.04016 http://dx.doi.org/10.4316/aece.2011.04016 R. D., TOMOIAGA, M., STRATULAT, The main goal of this work is to analyze the possibility of using a graphic processing unit in non graphical calculations. Graphic Processing Units are being used nowadays not only for game engines and movie encoding/decoding, but also for a vast area of applications, like Cryptography. We used the graphic processing unit as a cryptographic coprocessor in order accelerate AES algorithm. Our implementation of AES is on a GPU using CUDA architecture. The performances obtained show that the CUDA implementation can offer speedups of 11.95Gbps. The tests are conducted in two directions: running the tests on small data sizes that are located in memory and large data that are stored in files on hard drives. Wed, 30 Nov 2011 00:00:00 +0200 http://dx.doi.org/10.4316/aece.2011.04017 http://dx.doi.org/10.4316/aece.2011.04017 J. G., CALDERON-GUIZAR, E. A., TOVAR-GONZALEZ, Voltage stability margin in a power system is closely related with the availability of reactive power in the system. Therefore, adequate modeling of the reactive power sources becomes an important issue in this type of studies. The Minimum Singular Value of the load flow Jacobian matrix has been commonly used as a static voltage stability index. In this paper, such index is used to assess the influence on the static voltage stability limit of modeling the generators reactive power limits by its capability curve. Simulation results on a test system indicate that modeling the reactive power limits of the generating units by the simplified Qmin/Qmax approach, commonly used by most of the load flow programs, yields optimistic values for this voltage stability index. Wed, 30 Nov 2011 00:00:00 +0200 http://dx.doi.org/10.4316/aece.2011.04018 http://dx.doi.org/10.4316/aece.2011.04018 E., GANEA, D. D., BURDESCU, M., BREZOVAN, This paper presents a method for detection of salient objects from images. The proposed algorithms for image segmentation and objects detection use a hexagonal representation of the image pixels and a hypergraph structure to process this hierarchal structure. The main goal of the method is to obtain salient regions, which may be associated with semantic labels. The designed algorithms use color characteristic and syntactic features for image segmentation. The object-oriented model used for storing the results of the segmentation and detection allows directly annotation of regions without a processing of these. The experiments showed that the presented method is robust and accurate comparing with others public methods used for salient objects detection. Wed, 30 Nov 2011 00:00:00 +0200 http://dx.doi.org/10.4316/aece.2011.04019 http://dx.doi.org/10.4316/aece.2011.04019 F., HREBENCIUC, N., STROIA, D., MOGA, Z., BARABAS, Recent years showed a growing interest in the use of RFID technology in applications like distribution and storage of goods, supply chain and inventory. This paper analyses the current smart shelf solutions and presents the experience of developing an automatic reading system for smart shelves. The proposed system addresses the problem of reading RFID tags from items placed on multiple shelves. It allows the use of standard low cost readers and tags and uses a single antenna that can be positioned in specific locations at repeatable positions. The system proposes an alternative to the approaches with multiple antennas placed in fixed position inside the shelf or around the shelves, offering a lower cost solution by means of dedicated electromechanical devices able to carry the antenna and the reader to the locations of interest along a rail system. Moreover, antenna position can be controlled for three axis of movement allowing for extra flexibility and complete coverage of the shelves. The proposed setup is a fully wireless one. It contains a standard reader, electromechanical positioning actuators and wireless communication and control hardware offering power from integrated batteries. Wed, 30 Nov 2011 00:00:00 +0200