AECE - Advances in Electrical and Computer Engineering Journal

Simulation Analyses of Behaviours of Spatially Extended Predator-Prey Systems with Random Fluctuations

Wed, 02 Apr 2008 00:00:00 +0300

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.

Temperature Optimization of a Naphtha Splitter Unit

Wed, 02 Apr 2008 00:00:00 +0300

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.

The Role of Weather Indicators in Energy Consumption

Wed, 02 Apr 2008 00:00:00 +0300

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.

Speed Control of Switched Reluctance Motor Using Fuzzy Sliding Mode

Wed, 02 Apr 2008 00:00:00 +0300

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.

Correct Application of the Discrete Fourier Transform in Harmonics

Wed, 02 Apr 2008 00:00:00 +0300

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.

Spectral Shaping for Codes with P.S.D. Expressed by Rational Functions

Wed, 02 Apr 2008 00:00:00 +0300

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.

Client Provider Collaboration for Service Bundling

Wed, 02 Apr 2008 00:00:00 +0300

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.

Dynamically Integrating Knowledge in Applications An Online Scoring Engine Architecture

Wed, 02 Apr 2008 00:00:00 +0300

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.

Onto-SimFCA: A Two-step Mapping Method for Ontologies in MAS

Wed, 02 Apr 2008 00:00:00 +0300

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.

Ontology-Based Knowledge Organization for the Radiograph Images Segmentation

Wed, 02 Apr 2008 00:00:00 +0300

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.

User Head Movement Recognition and Interpretation System for Computer Interaction

Wed, 02 Apr 2008 00:00:00 +0300

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.

Modeling Shapes for Pattern Recognition: A Simple Low-Cost Spline-based Approach

Wed, 02 Apr 2008 00:00:00 +0300

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.

The Automated System for Identification of License Plates of Cars

Wed, 02 Apr 2008 00:00:00 +0300

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.

Integration of Simulink Models with Component-based Software Models

Mon, 02 Jun 2008 00:00:00 +0300

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.

Structure for Improving Short-Circuit Capability and the Method for Protecting the IGBT Devices

Mon, 02 Jun 2008 00:00:00 +0300

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.

Modeling and Sizing of Supercapacitors

Mon, 02 Jun 2008 00:00:00 +0300

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.

Transformer Internal Faults Simulation

Mon, 02 Jun 2008 00:00:00 +0300

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.

Automated Nuclear Quadruple Resonance Spectrometer

Mon, 02 Jun 2008 00:00:00 +0300

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.

Wireless System for Remote Tilt Measurement in Monitoring and Control Applications

Mon, 02 Jun 2008 00:00:00 +0300

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.

Virtual Lab for Wireless Sensor Networks

Mon, 02 Jun 2008 00:00:00 +0300

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.

A Genetic Algorithm Approach to DNA Microarrays Analysis of Pancreatic Cancer

Mon, 02 Jun 2008 00:00:00 +0300

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.

Static Test Compaction for VLSI Tests An Evolutionary Approach

Mon, 02 Jun 2008 00:00:00 +0300

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.

Methodological Principles of Pyramidal and Parallel-Hierarchical Image Processing on the Base of Neural-Like Network Systems

Mon, 02 Jun 2008 00:00:00 +0300

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.

Detecting and Tracking Multiple Users in the Proximity of Interactive Tabletops

Mon, 02 Jun 2008 00:00:00 +0300

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.

Training Neural Networks Using Input Data Characteristics

Mon, 02 Jun 2008 00:00:00 +0300

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.

The Uniform Engineering of Distributed Control Systems Using the OPC Specification

Mon, 02 Jun 2008 00:00:00 +0300

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.

Indoor Room Location Estimation

Mon, 02 Jun 2008 00:00:00 +0300

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.

Efficient Methods for Fast Shading

Mon, 02 Jun 2008 00:00:00 +0300

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.

High-Level Models for Transformation-Oriented Design of Hardware and Embedded Systems

Mon, 02 Jun 2008 00:00:00 +0300

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.

Minimum Field Requirements for Spin-Polarized Current Assisted Switching of Magnetization in Nanostructures with Uniaxial Anisotropy

Tue, 03 Feb 2009 00:00:00 +0200

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.

A Knowledge Management Scenario to Support Knowledge Applications Development in Small and Medium Enterprises

Tue, 03 Feb 2009 00:00:00 +0200

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.

Calculus of the Power Spectral Density of Ultra Wide Band Pulse Position Modulation Signals Coded with Totally Flipped Code

Tue, 03 Feb 2009 00:00:00 +0200

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.

Pulse width Modulation Command Systems Used for the Optimization of Three Phase Inverters

Tue, 03 Feb 2009 00:00:00 +0200

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.

Cogging Torque Reduction in Brushless DC Motors Using Slot-Opening Shift

Tue, 03 Feb 2009 00:00:00 +0200

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.

Optimal Power Flow Solution Using Ant Manners for Electrical Network

Tue, 03 Feb 2009 00:00:00 +0200

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.

Experimental Modelling of the Breakdown Voltage of Air Using Design of Experiments

Tue, 03 Feb 2009 00:00:00 +0200

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.

Energy Based Correlation Method for Location of Partial Discharge in Transformer Winding

Tue, 03 Feb 2009 00:00:00 +0200

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.

Radiofrequency Field Distribution Assessment in Indoor Areas Covered by Wireless Local Area Networks

Tue, 03 Feb 2009 00:00:00 +0200

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.

Cooperative Technique Based on Sensor Selection in Wireless Sensor Network

Tue, 03 Feb 2009 00:00:00 +0200

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.

Clustering Techniques in Load Profile Analysis for Distribution Stations

Tue, 03 Feb 2009 00:00:00 +0200

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.

The Application of Flow Injection Technology to Automating Cold Vapor Mercury Analyses in Aquatic Ecosystems

Tue, 03 Feb 2009 00:00:00 +0200

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.

Induction Motor Speed Estimator Using Rotor Slot Harmonics

Tue, 03 Feb 2009 00:00:00 +0200

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.

Speech Therapy Based on Expert System

Tue, 03 Feb 2009 00:00:00 +0200

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.

Preliminary Design of Reluctance Motors for Light Electric Vehicles Driving

Tue, 03 Feb 2009 00:00:00 +0200

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.

Influence of Different Types of Metal Plates on a High Frequency RFID Loop Antenna: Study and Design

Tue, 02 Jun 2009 00:00:00 +0300

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.

Data Complexity Metrics for XML Web Services

Tue, 02 Jun 2009 00:00:00 +0300

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.

Knowledge Acquisition from Historical Documents for Preserving Transylvanian Cultural Heritage

Tue, 02 Jun 2009 00:00:00 +0300

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.

A Comparative Study between Two Control Strategies for Matrix Converter

Tue, 02 Jun 2009 00:00:00 +0300

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.

A High Performance Space Vector Modulation - Direct Torque Controlled Induction Machine Drive based on Stator Flux Orientation Technique

Tue, 02 Jun 2009 00:00:00 +0300

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.

About a New Type of Fuse Based on the Controllable Fusing Effect

Tue, 02 Jun 2009 00:00:00 +0300

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.

Improving Power System Risk Evaluation Method Using Monte Carlo Simulation and Gaussian Mixture Method

Tue, 02 Jun 2009 00:00:00 +0300

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.

A New Linearization Technique Using Multi-sinh Doublet

Tue, 02 Jun 2009 00:00:00 +0300

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.

FEM Optimal Design of Energy Efficient Induction Machines

Tue, 02 Jun 2009 00:00:00 +0300

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.

Practical Procedures in Determining the Differential Mode Characteristics of EMI Power Supply Filters

Tue, 02 Jun 2009 00:00:00 +0300

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.

Calculation of Reactances for Ring Windings to Toroidal Inductors of Hybrid Induction Machine

Tue, 02 Jun 2009 00:00:00 +0300

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.

Rotor Pole Shape Optimization of Permanent Magnet Brushless DC Motors Using the Reduced Basis Technique

Tue, 02 Jun 2009 00:00:00 +0300

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.

Original Approaches for Solving Electromagnetic Interference Problems

Tue, 02 Jun 2009 00:00:00 +0300

D. D., MICU, R., MUNTEANU jr., G. C., CHRISTOFORIDIS, B., MANEA, A., CECLAN, 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.

Application of Functional Analysis on a SCADA System of a Thermal Power Plant

Tue, 02 Jun 2009 00:00:00 +0300

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.

Heavy Metals Extraction and Analysis in Aquatic Ecosystems with Automated Techniques

Tue, 02 Jun 2009 00:00:00 +0300

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.

Improved Nyquist Filters with a Transfer Characteristic Derived from a Staircase Characteristic Interpolated with Sine Functions

Tue, 02 Jun 2009 00:00:00 +0300

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.

Study and Design of a Linear Compressor of Voice-Coil Type

Tue, 02 Jun 2009 00:00:00 +0300

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.

Study of a Mini-Actuator with Permanent Magnets

Mon, 26 Oct 2009 00:00:00 +0200

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.

GEOBARN: A Practical Grid Geospatial Database System

Mon, 26 Oct 2009 00:00:00 +0200

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.

Graphical User Interface Aided Online Fault Diagnosis of Electric Motor - DC motor case study

Mon, 26 Oct 2009 00:00:00 +0200

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.

Simulations and Analysis and Operating Regime as Rectifier with Power Factor Correction of Two - Quadrant Converter with RNSIC

Mon, 26 Oct 2009 00:00:00 +0200

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.

A New Randomized Algorithm for Handling Scheduling Conflicts in Grids

Mon, 26 Oct 2009 00:00:00 +0200

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.

Information Structuring and Retrieval with Topic Maps for Medical E-Learning

Mon, 26 Oct 2009 00:00:00 +0200

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.

A Power-Efficient LC Quadrature VCO for RFID, Zigbee and Bluetooth Standards

Mon, 26 Oct 2009 00:00:00 +0200

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.

Robust and Low-Complexity Timing Synchronization Algorithm and its Architecture for ADSRC Applications

Mon, 26 Oct 2009 00:00:00 +0200

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.

Considerations on VoIP Throughput in 802.11 Networks

Mon, 26 Oct 2009 00:00:00 +0200

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.

Single-phased Fault Location on Transmission Lines Using Unsynchronized Voltages

Mon, 26 Oct 2009 00:00:00 +0200

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.

Multi-Motor Drives for Crane Application

Mon, 26 Oct 2009 00:00:00 +0200

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.

Feature Extraction for Facial Expression Recognition based on Hybrid Face Regions

Mon, 26 Oct 2009 00:00:00 +0200

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.

The Unit Histogram Concept for Scarce Statistical Information

Mon, 26 Oct 2009 00:00:00 +0200

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.

A Fluent Calculus Approach to Automatic Web Service Composition

Mon, 26 Oct 2009 00:00:00 +0200

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.

Simplified Design and Optimization of Slotless Synchronous PM Machine for Micro-Satellite Electro-Mechanical Batteries

Mon, 26 Oct 2009 00:00:00 +0200

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.

An Efficient Technique for Classification of Electrocardiogram Signals

Mon, 26 Oct 2009 00:00:00 +0200

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.

Modelling Imprecise Arguments in Description Logic

Mon, 26 Oct 2009 00:00:00 +0200

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.

Workload Characterization an Essential Step in Computer Systems Performance Analysis - Methodology and Tools

Mon, 26 Oct 2009 00:00:00 +0200

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.

Implementation of a Fuzzy Logic System to Tune a PI Controller Applied to an Induction Motor

Mon, 26 Oct 2009 00:00:00 +0200

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.

Construction and Design of a Modular Permanent Magnet Transverse Flux Generator

Sat, 27 Feb 2010 00:00:00 +0200

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.

Adaptive Automatic Gauge Control of a Cold Strip Rolling Process

Sat, 27 Feb 2010 00:00:00 +0200

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.

Fundamental Frequency Estimation of the Speech Signal Compressed by MP3 Algorithm Using PCC Interpolation

Sat, 27 Feb 2010 00:00:00 +0200

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.

Thermal Aspects Related to Power Assemblies

Sat, 27 Feb 2010 00:00:00 +0200

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.

Recent Research Progress in Fault Analysis of Complex Electric Power Systems

Sat, 27 Feb 2010 00:00:00 +0200

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.

Study of the Induction Machine Unsymmetrical Condition Using In Total Fluxes Equations

Sat, 27 Feb 2010 00:00:00 +0200

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.

Improvement of Dynamical Stability Using Interline Power Flow Controller

Sat, 27 Feb 2010 00:00:00 +0200

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.

Digital Adaptive Echo-Canceller for Room Acoustics Improvement

Sat, 27 Feb 2010 00:00:00 +0200

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.

A Simple and Efficient Control Strategy for Four-Switch Three-Phase Power Converters

Sat, 27 Feb 2010 00:00:00 +0200

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.

Power Factor Improvement in Switched Reluctance Motor Drive

Sat, 27 Feb 2010 00:00:00 +0200

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.

A Comparison of Double Convex and Double Concave Improved Nyquist Filters

Sat, 27 Feb 2010 00:00:00 +0200

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.

Iron Pole Shape Optimization of IPM Motors Using an Integrated Method

Sat, 27 Feb 2010 00:00:00 +0200

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.

Basic Consideration for Signal Processing Solutions Used in Sigma-delta Based ADC and DAC Converters

Sat, 27 Feb 2010 00:00:00 +0200

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.

Designing of Rescue Multi Agent System Based on Soft Computing Techniques

Sat, 27 Feb 2010 00:00:00 +0200

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.

Extending the Use of PLC Simulator Software in Student Laboratory Works

Sat, 27 Feb 2010 00:00:00 +0200

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.

Cluster Classification of Partial Discharges in Oil-impregnated Paper Insulation

Sat, 27 Feb 2010 00:00:00 +0200

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.

Elite Based Multiobjective Genetic Programming in Nonlinear Systems Identification

Sat, 27 Feb 2010 00:00:00 +0200

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.

Modelling of Switched Mode Fly-back Supply for Engineering Education

Sat, 27 Feb 2010 00:00:00 +0200

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.

New Code Matched Interleaver for Turbo Codes with Short Frames

Sat, 27 Feb 2010 00:00:00 +0200

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.

Path Loss Exponent Influence on Distance Estimation between Wireless Sensor Nodes

Sat, 27 Feb 2010 00:00:00 +0200

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.

Indirect Vector Control of an Induction Motor with Fuzzy-Logic based Speed Controller

Sat, 27 Feb 2010 00:00:00 +0200

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.

Scalar Control for Six Phase Matrix Converter Fed Double Star Induction Motor

Sat, 27 Feb 2010 00:00:00 +0200

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.

Corrections to "GEOBARN: A Practical Grid Geospatial Database System"

Sat, 27 Feb 2010 00:00:00 +0200

Z., HUANG, Y., FANG, X., XIE, M., PAN, No abstract available.

Power-Electronics Issues of Modern Electric Railway Systems

Mon, 31 May 2010 00:00:00 +0300

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.

Dynamic Analysis of Permanent Magnet Synchronous Generator with Power Electronics

Mon, 31 May 2010 00:00:00 +0300

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.

New Techniques for Implementation of Hardware Algorithms inside FPGA Circuits

Mon, 31 May 2010 00:00:00 +0300

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.

Development of Reliability Model for Wind Farm Power Generation

Mon, 31 May 2010 00:00:00 +0300

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.

Kalman Filter Based Tracking in an Video Surveillance System

Mon, 31 May 2010 00:00:00 +0300

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.

Static Simulation of a Linear Switched Reluctance Actuator with the Flux Tube Method

Mon, 31 May 2010 00:00:00 +0300

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.

About the Coupling Factor Influence on the Ground Fault Current Distribution on Overhead Transmission Lines

Mon, 31 May 2010 00:00:00 +0300

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.

Translation of the Speech Therapy Programs in the Logomon Assisted Therapy System

Mon, 31 May 2010 00:00:00 +0300

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.

Conceptual Implementation of Sample Rate Convertors for DACs

Mon, 31 May 2010 00:00:00 +0300

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.

Strategies for Power/Energy Saving in Distribution Networks

Mon, 31 May 2010 00:00:00 +0300

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.

Time of Arrival Based on Chirp Pulses as a means to Perform Localization in IEEE 802.15.4a Wireless Sensor Networks

Mon, 31 May 2010 00:00:00 +0300

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.

Induction Machine with Improved Operating Performances for Electric Trucks. A FEM-Based Analysis

Mon, 31 May 2010 00:00:00 +0300

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.

Genetic Algorithm based Servo System Parameter Estimation during Transients

Mon, 31 May 2010 00:00:00 +0300

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.

Cache Pattern with Multi-Queries

Mon, 31 May 2010 00:00:00 +0300

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.

Cellular Genetic Algorithm with Communicating Grids for Assembly Line Balancing Problems

Mon, 31 May 2010 00:00:00 +0300

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.

Hysteresis Modelling of Soft Magnetic Materials using LabVIEW Programs

Mon, 31 May 2010 00:00:00 +0300

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.

HL7 Messaging Engine with Customizable Translation System

Mon, 31 May 2010 00:00:00 +0300

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.

Hybrid Electric Vehicle Experimental Model with CAN Network Real Time Control

Mon, 31 May 2010 00:00:00 +0300

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.

Simulation of LTE Signaling

Mon, 31 May 2010 00:00:00 +0300

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.

Argumentative Support for Structured HACCP Plans

Mon, 31 May 2010 00:00:00 +0300

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.

Middleware Based Model of Heterogeneous Systems for SCADA Distributed Applications

Mon, 31 May 2010 00:00:00 +0300

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.

New High Performance Deterministic Interleavers for Turbo Codes

Mon, 31 May 2010 00:00:00 +0300

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.

Audio Source Localization using a Network of Embedded Devices

Mon, 31 May 2010 00:00:00 +0300

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.

Assessment of Distributed Generation Source Impact on Electrical Distribution System Performance

Mon, 31 May 2010 00:00:00 +0300

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.

Modeling and Simulation of a 12 MW Wind Farm

Mon, 31 May 2010 00:00:00 +0300

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.

Walking Robots Dynamic Control Systems on an Uneven Terrain

Mon, 31 May 2010 00:00:00 +0300

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.

A modified Adaptive Wavelet PID Control Based on Reinforcement Learning for Wind Energy Conversion System Control

Mon, 31 May 2010 00:00:00 +0300

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.

An Effective Framework for Distributed Geospatial Query Processing in Grids

Tue, 31 Aug 2010 00:00:00 +0300

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.

Heading Control System for a Multi-body Vehicle with a Virtual Test Driver

Tue, 31 Aug 2010 00:00:00 +0300

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.

A New Protection Scheme for High Impedance Fault Detection using Wavelet Packet Transform

Tue, 31 Aug 2010 00:00:00 +0300

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.

Indoor Inter-Robot Distance Measurement in Collaborative Systems

Tue, 31 Aug 2010 00:00:00 +0300

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.

Experimental Study and Comparative Analysis of Transients of Induction Motor with Soft Starter Startup

Tue, 31 Aug 2010 00:00:00 +0300

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.

A New MLP Approach for the Detection of the Incipient Bearing Damage

Tue, 31 Aug 2010 00:00:00 +0300

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.

Photovoltaic System with Smart Tracking of the Optimal Working Point

Tue, 31 Aug 2010 00:00:00 +0300

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.

Detailed Simulation of Transformer Internal Fault in Power System by Diakoptical Concept

Tue, 31 Aug 2010 00:00:00 +0300

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.

LCL Interface Filter Design for Shunt Active Power Filters

Tue, 31 Aug 2010 00:00:00 +0300

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.

Control Strategy for Three Phase Voltage Source PWM Rectifier Based on the Space Vector Modulation

Tue, 31 Aug 2010 00:00:00 +0300

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.

Static Frequency Converter with RNSIC Converter and Double Branch Inverter for Supplying Three-Phase Asynchronous Motors

Tue, 31 Aug 2010 00:00:00 +0300

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.

Effect of Circuit Breaker Shunt Resistance on Chaotic Ferroresonance in Voltage Transformer

Tue, 31 Aug 2010 00:00:00 +0300

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.

Observerless Scheme for Sensorless Speed Control of PMSM Using Direct Torque Control Method With LP Filter

Tue, 31 Aug 2010 00:00:00 +0300

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.

Adaptive Power Control with Overhearing Avoidance for Wireless Sensor Networks

Tue, 31 Aug 2010 00:00:00 +0300

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.

Measurement Settings Influence upon Energy Detection of TETRA Signals

Tue, 31 Aug 2010 00:00:00 +0300

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.

A Robust Blind Image Watermarking Method Using Local Maximum Amplitude Wavelet Coefficient Quantization

Tue, 31 Aug 2010 00:00:00 +0300

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.

PCA Fault Feature Extraction in Complex Electric Power Systems

Tue, 31 Aug 2010 00:00:00 +0300

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.

Shunt Active Filter in Damping Harmonics Propagation

Tue, 31 Aug 2010 00:00:00 +0300

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.

Approaches in High Impedance Fault Detection - A Chronological Review

Tue, 31 Aug 2010 00:00:00 +0300

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.

Performance Analysis of Microcellular Mobile Radio Systems with Selection Combining in the Presence of Arbitrary Number of Cochannel Interferences