WSEAS CONFERENCES. WSEAS, Unifying the Science

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Volume 8, 2009
Print ISSN: 1109-2734
E-ISSN: 2224-266X








Issue 1, Volume 8, January 2009

Title of the Paper:  Direct Solution of Compensated Radial Distribution Networks with Constant Impedance/Current Loads


Authors: Antonino Augugliaro, Luigi Dusonchet, Salvatore Favuzza, Mariano G. Ippolito, Eleonora Riva Sanseverino

Abstract: In this paper, a methodology to solve radial distribution networks, with constant current and/or impedance loads as well as shunt capacitor banks, is proposed. The techniques currently available to solve such systems are based either on iterative methods or on the bus impedance matrix. In both cases, the elaboration times are quite high since these are related, for iterative methods, to the overall number of iterations, and, for those methods based on the impedance matrix, to the inversion of the admittance matrix. The method developed here is the extension of a technique that is valid to solve networks made of impedances with one supply point. The methodology can also be applied in the solution, with the backward/forward methodology, of meshed systems having voltage-dependent loads and PV nodes. After having described the two cited networks’ analysis methodologies, the new methodology is developed and its implementation is described. The comparison of the computational performances, in terms of CPU times, between the iterative method, the method using the bus impedance matrix and the one developed in this paper provide evidence regarding the efficiency of the latter in strongly reducing the calculation times.

Keywords: Distribution networks, Backward/forward method, Ladder networks

Title of the Paper:  An Inversion/non-Inversion Dynamic Optically Reconfigurable Gate Array VLSI


Authors: Minoru Watanabe, Mao Nakajima, Shinichi Kato

Abstract: Up to now, an optically differential reconfigurable gate array taking a differential reconfiguration strategy and a dynamic optically reconfigurable gate array taking a photodiode memory architecture have been proposed. The differential reconfiguration strategy provides a higher reconfiguration frequency, with no increase in laser power, than other optically reconfigurable gate arrays, however the differential reconfiguration strategy can not achieve a high-gate-count VLSI because of the area occupied by the static configuration memory. On the other hand, the photodiode memory architecture can achieve a high-gate-count VLSI, but its configuration is slower than that of the optically differential reconfigurable gate array using equivalent laser power. So, this paper presents a novel inversion/non-inversion dynamic optically reconfigurable gate array VLSI that combines both architectures. It thereby achieves both advantages of rapid configuration and a high gate count. The experiments undertaken in this study clarify the effectiveness of the inversion/non-inversion optical configuration method.

Keywords: Field programmable gate arrays, Optical reconfigurations, Holographic memories, Optically reconfigurable gate arrays

Title of the Paper:  Study on the Applications of Extra-high Pressure Water Jet Technology


Authors: Yuefeng Fang, Xiaoyong Wang

Abstract: High-pressure Water Jet is a new technology that develops rapidly these decades. By the development of upsizing intelligentizing and customizing high-pressure water jet equipment, this technology has infiltrated into many application areas. The paper mainly discusses the mechanism of de-rusting by ultra-high pressure (short for u.h.p.)pure water as high as 200 to 250Mpa. It adopts u.h.p rotating waterjet, automatic wall-climbing and rust dregs vac sorbing and recycling. Mechanism of water-jtetting de-rusting is to scour and strip the rusty scale of the converted steel surface by normal hitting power and edge angle of waterjet and twisting force of rotating. The testing proves the mechanism equation.

Keywords: U.H.P Waterjet, De-rusting, Mechanism Testing

Title of the Paper:  Research and Design of Meter Reading System Based on ZigBee Wireless Sensor Network


Authors: Dechao Sun, Shaohua Zheng

Abstract: With the rapid development of wireless technologies, it is possible for Chinese automatic meter reading system (AMRS) to be equipped with wireless sensor networks due to their low-cost, simplicity and mobility. In the current study, we compared the advantages of ZigBee with other two similar wireless networking protocols, Wi-Fi and Bluetooth, and proposed a wireless solution for AMRS based on ZigBee technology. As an explorative application of ZigBee technology in AMRS, The design reduces the system cost and power consumption and improves the system’s flexibility and practicality.

Keywords: Wireless meter reading, ZigBee, IEEE802.15.4, JN5121, Profile

Title of the Paper:  Based on Embedded Database Greenhouse Temperature and Humidity Intelligent Control System


Authors: Sun Rong-Gao, Wan Zhong, Sun De-Chao

Abstract: The article based on embedded database of greenhouse temperature and humidity control system intelligent. Put forward by embedded database system set up in an ideal environment for data greenhouse temperature and humidity control, greenhouse crops in the process of growth under control. To address the growth of greenhouse crops in the process of temperature and humidity controlled environment is not ideal at the same time improve the efficiency of control and cost-effective system. The article focuses on the system design, the structure of the control system, hardware software make up and the system control strategy. At the same time outlines some research directions. This control system has a simple hardware structure, reliable data records, installation, maintenance and use of convenience features. Can used in kinds of temperature and humidity automatic control of environment of type.

Keywords: Embedded database, Temperature and Humidity, Control, data filtering, Greenhouse, Microcontrollers

Title of the Paper:  Research of the Chinese CAPTCHA System Based on AJAX


Authors: Dong Chen

Abstract: In this paper, we firstly introduce that CAPTCHA technology development and the various type of reading CAPTCHA, sound CAPTCHA, graph CAPTCHA at present. The second, we build one kind of the Chinese CAPTCHA model. The third, a new Chinese CAPTCHA system based on AJAX is proposed, which proceed to generate character characteristic based random problem and answer. On its performance, we show that the advantages of the Chinese CAPTCHA system due to its improved security and the reliability of the technology using it.

Keywords: CAPTCHA, AJAX, system, network, attacker, random, XML

Title of the Paper:  Design of MMIC Based on Mean Selection Methed and Research the Model of MMIC Non-Dissipative MESFET


Authors: Bolin Ke, Chunhua Li, Yang Ai-Min

Abstract: Multi-object mean selection, an efficient method applicable to design mean of monolithic microwave integrated circuits (MMIC), is presented in this article. Based on theories of Monte Carlo analysis and yield histogram, this method first extracts multi-object mean points from yield histograms, then picks out optimal mean upon them by yield comparison. In the implementation of this method , a combination of interpolation sampling, parametric sampling and sample recognition methods is developed to improve Monte Carlo analysis, which keeps accuracy and attains more efficiency. With this advanced numeric physical models, the method of multi-object mean selection becomes far more accurate and reliable for MMIC designing. Analysis on the principle and characteristic of Non-dissipative MESFET mixer circuit has been discussed in detail in this paper. During research of CAD of this type of mixer,the technique of expanding the MESFET model has been offered. On the basis above,the 12.4~18GHz non-dissipative MESFET mixer have been designed . The mixer performs -3dB of conversion gain.

Keywords: CAD, MESFET mixer, MMIC, Transfer characteristics, Local oscillation, Non-dissipative

Title of the Paper:  Dynamic Application of Slicing Technique in Grid Calling and Network Resources


Authors: Lixia Wang, Aimin Yang, Yaohui Li, Liting Gao, Tieying Liu

Abstract: The grid links all resources in different structures widespread geographically into one logical system via internet, characterized with complexity of network structure, dynamism of network resources and autonomy of each LAN. The high-efficient management of grid resources and high-efficient scheduling of tasks are the important contents in today’s net grid research. Slices technology is the present quite popular popular technology, the application domain is widespread. The grid technology and the slice technology fuse in together, may create the more reasonable task scheduling and the scheduling of resources. In this article we divide the tasks into some small tasks assigned with scheduling priorities for each level, and then slice all resources in network into some time slices assigned with resource priorities according to trust mechanism. It promotes the effectiveness and high-efficiency by arranging task scheduling and resource scheduling in priority.

Keywords: Grid computing, Slicing Technique, Slice Min—min algorithm, Trust mechanism, Load Balancing, Distributional dispatch, Toughness, Correspondence detention

Title of the Paper:  The Optimal Design and Simulation of Helical Spring based on Particle Swarm Algorithm and Matlab


Authors: Xiao Qimin, Liu Liwei, Xiao Qili

Abstract: Optimal problem is often met in engineering practice. The method to solve complex optimal problem is always studied by people. Springs are important mechanical members which are often used in machines to exert force, to provide flexibility, and to store or absorb energy. Helical spring is the most popular type of springs. The method of helical spring optimization is a typical one which can be used to solving other mechanical optimal design problem. Particle Swarm Optimization algorithm is a good method in solving optimal problem. MATLAB is a high-performance language for technical computing and is an easy tool for us to simulate the optimization. In this paper, we mainly introduce the optimization of helical spring based on particle swarm algorithms and simulation in MATLAB. Directed by the theory of Particle Swarm Optimization algorithm, with the minimum weight of helical spring as objective function, with d, D2 and n as design variables, with shear stress, maximum axial deflection, critical frequency, bucking, fatigue strength, coils not touch, space and dimension as constraint conditions, the complex helical spring optimal design mathematics model with three design variables and fourteen inequality constraints conditions is established. When the model is simulated in MATLAB the minimal optimal value of variables and the minimal weight of helical spring can be obtained. Simulating Result shows that Particle Swarm Optimization is practical in solving complicated optimal design problems and effectively on avoiding constraint of solution. The fundamental idea, the method of establishing mathematic model, the simulation process in MATLAB of helical spring can be used for reference to other similar mechanical optimal design.

Keywords: Particle Swarm Optimization (PSO), fitness value, local best value, global best value, helical spring, optimal design, mathematic model , objective function, design variables, constraints condition, shear stress, deflection, critical frequency, bucking, f

Title of the Paper:  SAR Image Localization and Target Recognition Research Based on the Azimuth Circle Adjustment


Authors: GuangYang, Xiaojuan Wang, Dejun Li, BaiZhang, Kun Gao

Abstract: According to the work mechanism of space synthetic aperture radar (SAR), this text introduced the localization algorithms of SAR image and the method of system error adjustment. On the basis of the concept of the azimuth circle and the combination of the north direction coordinate system of geography, carries on the adjustment to the localization data, so increased the SAR image localization accuracy at large scale, combines the simulated data and the image of Radarsat satellite, validate the localization algorithm and the adjustment method. The results had indicated that this algorithm might enable the localization accuracy of Radarsat image to achieve 400-600m, if the establishment of earth model might more accurate, the ground station could provide the more precise orbital data, the localization accuracy may further enhance. After the studying localization, summarizes to the research evolvement and the development uptrend of the goal pretreatment, the automatic detection and the recognition aspect in the SAR imagery, table the proposal for the future SAR image’s recognition and the localization research.

Keywords: ITSM, Process Model, Framework, ITIL, UML

Title of the Paper:  Monitoring of the Pressure Inside the Cylinder for an Internal-Combustion Engine


Authors: Sorin Ratiu, Gabriel Nicolae Popa, Vasile Alexa

Abstract: This work presents the achievement of a monitoring, recording, processing and interpretation concept, at laboratory scale, of the pressure inside the combustion chamber for a spark-ignition engine, based on electronic equipment, which measures the values of 17 parameters that describe the operation of an internal-combustion engine. The measured pressure depends on the crankshaft’s position. Is used a pressure transducer with strain-gauge socket, and measurement of the crankshaft’s position with a speed transducer with variable reluctance. From experimental data, on one hand, can be analyzed the pressure modification in the combustion chamber depending on the crankshaft’s position, and on the other hand, the maximum pressure modification in the cylinder depending on the speed.

Keywords: Internal-combustion engine, Sensors, Cylinder, Pressure, Speed

Title of the Paper:  Assessment of Power Quality for Line Frequency Coreless Induction Furnaces


Authors: Angela Iagar, Gabriel Nicolae Popa, Corina Maria Dinis

Abstract: This paper presents a study about power quality problems generated by line frequency coreless induction furnaces. We analyzed a furnace with 12.5 t capacity of cast-iron. The measurements have been made in the primary of the furnace transformer, on the MV line, using the CA8334 three-phase power quality analyser. Experimental results emphasized the presence of harmonics and interharmonics in the phase voltages and harmonics in the currents absorbed from the MV network. Further to harmonic analysis of the measured signals, we have been proposed some optimization methods for operation of analyzed furnace, in such way to comply with the European norms of Electromagnetic Compatibility (EMC).

Keywords: Power quality, Harmonics, Interharmonics, Induction furnace

Title of the Paper:  Quadratic Fluency DA Functions as Non-Uniform Sampling Functions for Interpolating Sampled-Values


Authors: Kazuki Katagishi, Kenichi Ikeda, Mitsuteru Nakamura, Kazuo Toraichi, Yasuhiro Ohmiya, Hitomi Murakami

Abstract: Interpolation for sampled-values with non-uniform sampling points is required for various cases of signal processing. In such a case, sampling functions are useful to interpolate sampled-values and then to generate signals as a linear combination of the sampling basis weighted by a sequence of the sampled-values. This paper proposes sampling functions for non-uniform sampling points, each of which is composed with piecewise polynomials of degree 2. We name the sampling functions the fluency DA functions of degree 2. The fluency DA functions generate smooth and undulate signals from a sequence of sampled-values.

Keywords: Fluency information theory, Fluency DA functions, Interpolation, Non-uniform sampling functions, Piecewise polynomials

Title of the Paper:  Transformer Fault Diagnosis Based on Reasoning Integration of Rough Set and Fuzzy Set and Bayesian Optimal Classifier


Authors: Hongsheng Su, Haiying Dong

Abstract: In accordance with intelligent complementary strategies, a new transformer fault diagnosis method is proposed based on rough set (RS) and fuzzy set (FS) and Bayesian optimal classifier in this paper. Through RS reduction, the diagnostic decision table is greatly simplified and fault symptoms information is compressed, dramatically, and the minimal decision rules can be obtained. In the light of the minimal decision rules, the complexity of Bayesian reasoning and difficulties of fault symptom acquisition are dramatically decreased. Moreover, probability reasoning may be realized applying Bayesian optimal classifier, it can be used to describe the characteristics of fault information and investigate the fault reasons of transformer. In the end, a practical application in transformer fault diagnosis indicates that the proposed method is very effective and intelligent and ubiquitous.

Keywords: Rough set, Fuzzy set, Bayesian optimal classifier, Fault diagnosis, Information entropy, Intelligent complementary, Transformer

Title of the Paper:  The Star-Routing Algorithm Based on Manhattan-Diagonal Model for Three Layers Channel Routing


Authors: Jiann-Chyi Rau, Po-Han Wu, Chia-Jung Liu, Yi-Chen Lin

Abstract: In this paper, we employ gridded model for channel routing and place the terminals which are horizontally aligned. We have developed a two-layer channel router that can eliminate the constraints due to overlap. The proposed approach is suitable for cell/IP-based channel-less circuit with a few channels. Our developed tool can route the nets in nearly linear time achieving to the advantage of time to market, and lead to the area overhead of 6.34% increase in average. The area overhead results from the space insertion, and we also have shown that the proposed algorithm can achieve 100% routing on most ISCAS’85 benchmarks. In addition, the number of channel tracks can be minimized by our algorithm. We proposed the star-routing algorithm for three layers channel routing using Manhattan-Diagonal Model to solve the channel routing problem. We drew up the smaller grid-model, and in order to avoid violating the DRC, so the algorithm has a restriction for the third metal-layer in routing step. We don’t need to increasing extra spaces and moving any pins in order to finish the routing completely. The foregoing is good for hard blocks to finish the routing easily, and it does not replace the location of hard blocks because of routing incompletely. Therefore, the height of the entire routing channel can reduce a lot.

Keywords: Channel routing, Manhattan-Diagonal Model, Electronic Design Automation (EDA)

Title of the Paper:  New Approach Regarding the Electroerosion Estimation of the Circuit Breakers Contacts


Authors: Catalin Pancu, Adrian Baraboi, Maricel Adam

Abstract: In the estimation of the circuit breakers technical state, it is very important to knows its contacts electroerosion. The electroerosion depends on the following main parameters: switching number realised, currents values that have been switched, existence time of electric arc at each switching. Electroerosion estimation of the contacts realised in operation leads to an overestimation inducing a supplementary maintenance. Thus it is necessary an evaluation of short-circuit currents in the mounting place of circuit breakers from electrical installations and a reconsideration of switching number at short-circuit of its. In this paper is shown an experimental model of an embedded intelligent system for the technical state evaluation of the switchgears contacts, from electroerosion point of view. This approach has the advantage that the architecture can be used, also, for the monitoring of the some cinematic parameters for the operating mechanism, like as: closing/opening velocity, closing/opening time, the stored energy in the operating mechanism and others.

Keywords: Circuit breaker, Contacts electroerosion, Contacts wearing, Intelligent system, Microcontroller

Title of the Paper:  Modification of the Cockcroft-Walton Charge Pump by using Switched Capacitors Technique for Improved Performance under Capacitive Loads


Authors: Davor Vinko, Tomislav Svedek, Tomislav Matic

Abstract: This paper presents a modified Cockcroft-Walton charge pump designed for driving capacitive or low current resistive loads. The proposed modification by using switched capacitors technique shows great improvement in output voltage levels that it achieves, and in number of capacitors needed for reaching a certain voltage level. Also, it requires no additional clocking scheme besides the present single phase AC signal. The proposed Switched Cockcroft-Walton (SCW) charge pump was simulated and compared with the CW charge pump.

Keywords: Charge pump, Driving capacitive loads, Heap pump, High-voltage generation, Switched capacitors, Voltage multiplier

Issue 2, Volume 8, February 2009

Title of the Paper:  Automated Meter Reading System for Heat Costs Allocation


Authors: Ioan Lie, Virgil Tiponut, Ivan Bogdanov, Sabin Ionel, Catalin Daniel Caleanu

Abstract: The paper presents the design and the implementation of an automated meter reading system for heat costs allocation. The system was developed on three levels: the data acquisition level – where data are recorded from field with costs allocators installed on the radiators; a data concentration level – were data registered by allocators are read at a predetermined time interval with data concentration units and a data processing level – for uploading information in a PC hosted data base for various works afterwards. For each level was defined the hardware requirements and the software specifications including the communications modules, the meter and the user interfaces. A PWM data encoding was proposed as an alternative encoding for wireless communication through RF between data acquisition and concentration levels. The system uses RF for data transmission but also includes a pair of RFID modules facilitating remote programming and diagnostic procedures. In order to fulfill the low power requirements the dedicated modules costs allocator and data collection unit were implemented around MSP430 low power microcontrollers.

Keywords: Costs allocator, Sensor network, Temperature measuring, Data concentrator, Radio communication, Automatic meter reading, RFID, Low power

Title of the Paper:  The Analysis of Circuit Breakers Kinematics Characteristics using the Artificial Neural Networks


Authors: Maricel Adam, Adrian Baraboi, Catalin Pancu, Sorin Pispiris

Abstract: The paper presents the required parameters in the evaluation of the technical state for the High Voltage (HV) circuit breakers. It details some aspects regarding the influence of the kinematics characteristics to the circuit breakers performances. Also, it presents a possibility to use the artificial neural networks (ANN) in the analysis of the circuit breakers kinematics characteristics, in order to diagnostic their technical state. The required database necessary for learning of ANN has determined through the modelling of the mechanical system of movement transmission, using the systems of electrical nature, with RLC elements.

Keywords: Circuit breaker, Kinematics characteristics, Modelling and simulation, Monitoring, Diagnostic, Artificial neural network

Title of the Paper:  Steady State Modelling of Induction Motor Operating with Unbalanced Supply System


Authors: Kanwarjit Singh Sandhu, Vineet Chaudhary

Abstract: Three phase supply system is found to be quite balanced in both magnitude and displacement at the generation levels but it is not so at distribution end. Voltage unbalance which is a common and global phenomenon is found to be very effective in deteriorating the performance of electrical apparatus at user end. Such environment badly affects the performance of induction motors, an important class of electric machines which is widely used in industrial. Present paper is an attempt to tackle such operations with specific recommendations & proposals. Symmetrical component approach is adopted to estimate the performance of a three-phase induction motor operating with unbalanced supply system. Further MATLAB/SIMULINK & PSIM environments have been used simultaneously for simulation purpose. A new approach is proposed to rerate the motor operating with voltage unbalance.

Keywords: Abnormal operation, Three Phase Induction Motors, Rerating, Steady state Analysis, Unbalanced Supply

Title of the Paper:  Improved Design of Three-Level NPC Inverters in Comparison to Two-Level Inverters


Authors: Ahmad Radan, Hengameh Kojooyan Jafari

Abstract: As voltage source 3-level NPC inverters are suitable for AC drives in average voltage and FACT applications in distribution systems, this report introduces optimized design of 3-level NPC inverter by decreasing inverter losses and costs. At first optimization parameters and application functions of losses are introduced[1], then by using MATLAM6.5 program and IGBT, diodes, switching frequency and load current typical input parameters [1] are considered then by SPWM switching algorithm in program, optimized RGon , RGoff and gate voltage for 3-level NPC inverters are calculated for minimizing switching and conduction losses of inverter among all amounts of calculated RGon , RGoff and gate voltage in comparison to optimized design of 2-level inverters[1]. Then results of NPC optimization are applied for simulation of improved NPC, using SVM switching algorithm as the best method of switching and results are presented.

Keywords: Design, IGBT inverter, NPC, SPWM, SVM, loss model, optimization

Title of the Paper:  Simulation of Doubly-fed Machine with Improved Wind Turbine


Authors: Hengameh Kojooyan Jafari

Abstract: Most of wind turbines use induction generators that are very reliable with low costs [2], but when it is straightly connected to the grid, maximum power is not accessible [1] and only a few change of speed between maximum speed and synchronous speed is possible [1].
In this report, a doubly-fed induction generator with winding-rotor configuration, external rotor resistance and external rotor source that has a variable phase and amplitude is used. This doubly-fed induction generator has larger range of change of speed than induction generator and its application in wind systems is very common. Also in doubly-fed machine, both active and reactive power control is possible [3].
In this report, a doubly-fed induction machine with an improved wind turbine has been simulated, then with selecting suitable control parameters by open loop controlling, maximum turbine active power at an adapted speed is exerted to the grid and the results is presented.

Keywords: Doubly-fed machine, Wind Turbine, Gearbox ratio, Low speed shaft, High speed shaft.

Title of the Paper:  Online State Diagnosis of Transformer Windings based on Time-frequency Analysis


Authors: Yuying Shao, Zhushi Rao, Zhijian Jin

Abstract: The power transformers are the key equipments in the power system. To keep the stable operation of the transformers, it’s necessary to get their state information on a real-time basis. Therefore, the efficient online monitoring system is developed which obtain the state of the transformers by the accelerometers attached on the tank. The locations of these accelerometers can be determined by the method of varying current with constant frequency. The vibration intensity change is used to initially detect the windings' state by online monitoring the vibration signal of the shocks. Then the time-frequency analysis further processes these signals in order to detect the fault information contained. The short-circuit experiments have been done on the large power transformer of 50000KVA, which finds that the time-frequency analysis can be used to more precisely detect the fault characteristics of windings. Compared with traditional off line short circuit reactance method, the time-frequency analysis is more effective.

Keywords: Transformer winding, time-frequency analysis, Vibration intensity,Short-circuit reactance, Condition monitoring

Title of the Paper:  The Circuit Design of Current-Mode Image Sensor Embedded Smooth Spatial Filter with Flash A/D Converter


Authors: Chia-Chun Tsai, Huang-Chi Chou, Trong-Yen Lee

Abstract: The paper presents a current-mode CMOS image sensor embedded smooth spatial filter algorithm with a flash analog-to-digital (A/D) converter. The sensor includes a 66?66 pixel array with an on-chip 6-bit A/D converter that can identify the output value of pixels in gray level resolution. The last row of pixel cells (1?66) based on the double sampling is used for reducing fixed pattern noise (FPN). Processing circuits are dedicated for the spatial filter algorithm and support reusability to increase the image processing speed and to reduce the design complexity and chip area. The sensor chip has been designed and implemented in TSMC 0.35?m 2P4M CMOS mixed-mode process. Experimental results show that each pixel occupies a area of 15.8?m?10.6?m with a fill factor of 37.2%. The power consumption is 35.15mW when the sensor operates at 175 frames/second.

Keywords: Image senser, smooth spatial filter, Flash A/D converter, pixel cell, CMOS process

Title of the Paper:  An Adaptive Scheme for Distributed Dynamic Security Assessment of Large Scale Power Systems


Authors: Xing-Zhi Wang, Zheng Yan, Li Li

Abstract: The requirements for significant computational resources imposed by dynamic security assessment applications have led to an increasing interest in the use of parallel and distributed computing technologies. This paper presents an adaptive scheme that involves user-friendly flat application program interfaces for scripting and an object-oriented programming environment for distributed dynamic security assessment implementation. Functional parallelism and data parallelism are supported by each of the message passing interface model and TCP/IP model. Adaptive stochastic-based objectives and conservative parameter prediction techniques are used to produce more efficient data parallelism. Tests for a 39-bus network and a 3872-bus network are reported, and the results of these experiments demonstrate that the proposed scheme is able to execute the distributed simulations on either stand-alone personal computers, cluster systems, or a computational grid infrastructure and provide efficient parallelism for the given environment.

Keywords: Adaptive systems, graph partitioning, parallel processing, parameter estimation, power system

Title of the Paper:  Forward Transmission over a Multipath Faded Channel in a DS CDMA System


Authors: Abdel-Rahman Al-Qawasmi, Omar Al-Ayasrah, Ayman Al-Lawama

Abstract: The pseudorandom spreading sequence in the forward transmission in the IS -95 system is assigned only to individual base stations . To separate users, the system assigns orthogonal (Hadamard) sequences to each of them. In this paper, a different scheme for the forward transmission is considered. In this scheme pseudorandom sequences are u sed, instead of employing orthogonal spreading sequence for individual users. The effect of fade amplitudes, phase shifts, time -mismatching and AWGN on the detection process of Gold Sequence Spread Spectrum Signal (GSSSS) is considered.

Keywords: Gold sequence, Rake receiver, Time-mismatching, QPSK-GS SS receiver

Title of the Paper:  Joint Optimization Algorithm for Network Reconfiguration and Reactive Power Control of Wind Farm in Distribution System


Authors: Jingjing Zhao, Xin Li, Jiping Lu, Congli Zhang

Abstract: In recent years, the number of small size wind farms used as DG sources located within the distribution system are rapidly increasing. Wind farm made up with doubly fed induction generators (DFIG) is proposed in this paper as the continuous reactive power source to support system voltage control due to the reactive power control capability of DFIG. In the distribution system, considering network reconfiguration and wind farm reactive power control are both used to improve power profile and they have an inherent coupling relationship, in this paper, a joint optimization algorithm of combining reactive power control of wind farm and network reconfiguration is proposed. In the proposed joint optimization algorithm, an improved hybrid particle swarm optimization with wavelet mutation algorithm (HPSOWM) is developed for voltage profile improvement which utilized reactive power output of wind farm as the control variable. In each particle updating instance at each iteration of reactive power output optimization algorithm, a binary particle swarm optimization algorithm (BPSO) is utilized to find the optimal network structure. Finally, classical 16-node feeder is used as a test case to evaluate the algorithm. The experimental result demonstrates the correctness of the algorithm.

Keywords: Wind farm, DFIG wind turbine, reactive power control, network reconfiguration, particle swarm optimization

Title of the Paper:  Semiconductor Nanointerface Eigenstate-Photoevolution


Authors: E. A. Anagnostakis

Abstract: The dynamics of photonic evolution for the eigenstate of a generic semiconductor-nanointerface is studied in terms of its two-dimensional electron gas (2DEG) fundamental-sublevel eigenenergy’s correlation with respective 2DEG areal density, versus instantaneous cumulative photonic intake. Application of this treatment to the experimental photoresponse of typical modulation – doped optoelectronic nanodevices leads to a realistic tracing of the nanostructure pertinent photodynamics.

Keywords: Nanotechnology, optoelectronics, functional eigenstate, nanodevice, photodynamics, two-dimensional electron gas

Title of the Paper:  High Speed Gate Level Synchronous Full Adder Designs


Authors: Padmanabhan Balasubramanian, Nikos E. Mastorakis

Abstract: Addition forms the basis of digital computer systems. Three novel gate level full adder designs, based on the elements of a standard cell library are presented in this work: one design involving XNOR and multiplexer gates (XNM), another design utilizing XNOR, AND, Inverter, multiplexer and complex gates (XNAIMC) and the third design incorporating XOR, AND and complex gates (XAC). Comparisons have been performed with many other existing gate level full adder realizations. Based on extensive simulations with a 32-bit carry-ripple adder implementation; targeting all the three process, voltage and temperature (PVT) corners of the high speed (low Vt) 65nm STMicroelectronics CMOS process, it was found that the XAC based full adder is found to be delay efficient compared to all its gate level counterparts, even in comparison with the full adder cell available in the library. The XNM based full adder is found to be area efficient, while the XNAIMC based full adder offers a slight compromise with respect to speed and area over the other two proposed adders.

Keywords: Combinational logic, Full adder, High performance, Standard cells, and Deep submicron design

Issue 3, Volume 8, March 2009

Title of the Paper:  Toward in Vivo Digital Synchronous Sequential Circuits


Authors: Miha Moskon, Monika Ciglic, Nikolaj Zimic, Miha Mraz

Abstract: We present the model of a first digital synchronous sequential circuit, i.e. 1-bit synchronous counter, which is about to be realized within the living cell. Mathematical model was constructed upon gene expression based logic with ordinary differential equations (ODEs), particularly Hill equations. The behaviour of the counter was simulated in Matlab/Simulink environment. With the promising simulation results presented in the paper physical realization of the circuit described within the living cell can be initiated. Introduction of synchronization with a special signal, i.e. clock signal, brings many benefits to the field. Realization of such circuit would therefore present an important step toward the construction of complex biological information processing capable systems.

Keywords: Synthetic biology, Protein-based computing, Sequential logic, Synchronization, Ordinary differential equations, Biological modelling, Circuits, Master-Slave flip-flop

Title of the Paper:  Responsivity Robustness of Radioactivity-Irradiated Nanosensors


Authors: E. A. Anagnostakis

Abstract: The responsivity robustness of representative photodetector-nanointerfaces with respect to the extent to which they exhibit radiation hardness and the degree of functionally tolerable radioactivity-induced responsivity de-emphasis, against increasing cumulative radioactivity-dose, is notionally considered and modelled. Systematic experimental findings concerning commercial p-i-n photodetectors being exposed to regulated successive α-particle bombardments appear in compliance with the analysis and reveal noteworthy trends of radiation-effected optoelectronic-yield alteration.

Keywords: Responsivity Robustness, Nanosensors, Radioactivity Irradiation Radiation-Hardness, Optoelectronic Reliability, Photodetectors, Photoresponsive Nanointerfaces, Quantum Efficiency & Detection Yield.

Title of the Paper:  Computer-Aided Design, Analysis and Optimization of HMIC SOP Broadband Balanced Amplifier


Authors: Said H. Ibrahim

Abstract: The purpose of this paper is to present a complete design and analysis of new HMIC 3.5-4.5 GHz broadband balanced amplifier modules using microstrip technology. Two different modules are designed and analyzed. Each module is implemented in a single substrate. The first module used Lange couplers as power splitters and combiners while the second used branch couplers. The components of the modules are designed using full-scale computer simulation program, performed by the author and named as MSDES, which takes fully into account all the discontinuities included in the microstrip lines; while the modules are analyzed and optimized using APLAC V7.61 software. A short and efficient CAD procedure for the broadband amplifier design is introduced. The first step is to design an initial narrowband high-gain microstrip amplifier at a center frequency equal to 4 GHz. The second step is to optimize the initial lengths and widths of the input and output microstrip-matching circuits to get the broadband amplifier over the range 3.5-4.5 GHz. The analyses of both narrow and broadband amplifiers are introduced in addition to the complete analysis of the designed 3.5-4.5 broadband balanced amplifier modules. The analysis of the designed balanced amplifier modules shows better efficiency and good performance. The complete AC schematic diagrams of the designed balanced amplifier modules are presented. These modules can be used in many applications including sensors, pulse Doppler communications, airborne radars, traffic control radars and satellite communications.

Keywords: Computer-Aided Design and Analysis, Microstrip Technology, Microwave Devices and Systems

Issue 4, Volume 8, April 2009

Title of the Paper:  A Variable Voltage MPPT Control Method for Photovoltaic Generation System


Authors: Liu Liqun, Wang Zhixin

Abstract: To increase the output efficiency of a photovoltaic (PV) generation system it is important to have an efficient maximum power point tracking (MPPT) technique. This paper describes the analysis, design and implementation of an efficient tracking method for a stand-alone PV generation system, which automatically adjusts the reference of output voltage to track the maximum power point (MPP) by using the expiatory program. Compared with the conventional constant voltage (CV) method, the proposed approach can effectively improve the tracking speed and accuracy simultaneously. Furthermore, an improved control system is designed for the pulse-width-modulation (PWM) inverter to achieve the objective of MPPT. Theoretical analysis and principle of proposed method are presented and simulation results are given to verify the validity of control method.

Keywords: Maximum power point tracking (MPPT), Variable voltage, Pulse-width-modulation (PWM), Photovoltaic generation system, Solar energy

Title of the Paper:  An Equilibrium Model for the Joint FTR/FGR Auction Market


Authors: Jianlin Yang, Zheng Yan, Wen Jiang

Abstract: As an important instrument to hedge against the risk of congestion charges, transmission right has been successfully implemented in practice. There are two basic transmission rights, point-to-point financial transmission right (FTR) and flow-based right (FGR). The equilibrium model for the joint FTR/FGR auction market is established in this paper. Every TR (transmission right) bidder can bid for any portfolio of FTRs and FGRs in this model, and the contingency constraints are also involved in the simultaneous feasible test (SFT). Besides, the analysis for the established model is also presented. The resulting equilibrium model is formulated in terms of a mixed linear complementarity problem, which is converted into the computation of a convex quadratic programming in this paper. The standard PJM-5-bus system is used to illustrate the proposed equilibrium model.

Keywords: FTR obligation, FTR option, FGR, simultaneous feasible test, convex quadratic programming

Title of the Paper:  Electrical Equivalent Circuit of Ceramic Insulators with RTV Silicone Rubber Coating and Computer Simulation of Leakage Currents


Authors: Suwarno, Fari Pratomosiwi

Abstract: During operation, high voltage insulators may severe a certain degree of pollution which may reduce their performances. RTV silicone rubber coating was proposed to improve the performances of outdoor ceramic insulators especially in highly polluted areas. This paper reports experimental results on the leakage current (LC) on RTV silicone rubber-coated ceramic insulators. The samples used were 20 kV post-pin ceramic insulators. The samples were coated by RTV silicone rubber from Dow Corning. There were 2 kinds of samples. The first one is clean and the second one is kaolin-salt polluted. The sample was put in a climate chamber under certain condition of fog. AC voltage of 50 Hz was applied to the sample and the leakage current flowed on the insulator surface was measured by measuring the voltage across a series resistance using a Digital Oscilloscope with sampling rate of 1 GS/s. The digital data was transferred to a personal computer trough a GPIB for further analysis. The experimental results showed that LC waveforms of RTV-coated insulators in general are distorted from sinusoidal applied voltage. The LC waveforms are symmetrical for positive and negative half cycles and no flashover was observed for applied voltage up to 60 kV. The THD as well as magnitude of the LC increased with applied voltage for both clean and kaolin-salt polluted samples. From the experimental results, electrical equivalent circuit models are proposed. Using the proposed model computer simulation of leakage current waveforms was done using APT/EMTP under various conditions and applied voltages. The simulation was done by choosing appropriate values of capacitances, non linearity and arc models. The simulated LC waveforms were compared to those obtained from experiment. The similarity of the LC waveforms was determined by comparing the LC magnitude, THD, dominant harmonic components and symmetry. The results indicated that simulated leakage current waveforms were similar to those obtained from experiment. These revealed the validity of the proposed model.

Keywords: Ceramic insulator, RTV coating, equivalent circuit, leakage current, harmonics, computer simulation

Title of the Paper:  CMOS Implementation of an Artificial Neuron Training on Logical Threshold Functions


Authors: V. Varshavsky, V. Marakhovsky, H. Saito

Abstract: This paper offers a new methodology for designing in CMOS technology analog-digital artificial neurons training on arbitrary logical threshold functions of some number of variables. The problems of functional ability, implementability restrictions, noise stability, and refreshment of the learned state are formulated and solved. Some functional problems in experiments on teaching logical functions to an artificial neuron are considered. Recommendations are given on selecting testing functions and generating teaching sequences. All results in the paper are obtained using SPICE simulation. For simulation experiments with analog/digital CMOS circuits, transistor models MOSIS BSIM3v3.1, 0.8μm, level 7 are used.

Keywords: Artificial neuron, CMOS implementation, learnable synapse, excitatory and inhibitory inputs, learning process, learning sequence, refreshment process, test function, threshold logical element, threshold logical function, Horner's scheme, Fibonacci sequence

Issue 5, Volume 8, May 2009

Title of the Paper:  Design and Analysis of SOP-HMIC Transceiver with Integrated T/R Switch


Authors: Said H. Ibrahim, El-Sayed A. El-Badawy

Abstract: The demand for higher performance systems that are smaller and have the potential to be more cost effective has lead the hardware designers to adopt integration of many components and modules in a package (SOP) or on a chip (SOC). Two compact SOP (single-substrate) SO-HMIC transceivers with integrated T/R switch modules for high-resolution sensor application have been demonstrated. These modules contain singly-balanced diode mixer; using either rate-race or Lange coupler; lowpass filter, 7-dB power splitter using branch coupler and T/R switch. A new and efficient methodology is investigated for the design of microstrip T/R switch. The components of the modules are designed using the full-scale computer simulation program performed with the authors, while they are analyzed and optimized using the Aplac V7.61 software. The analysis of the designed transceiver modules is introduced which reflects a good performance and achieves a higher efficiency.

Keywords: Computational Microstrip Circuit Design, Microwave Circuits and systems, Computer Aided Design (CAD)

Title of the Paper:  A Novel Soft-Switching Converter for Switched Reluctance Motor Drives


Authors: Kuei-Hsiang Chao

Abstract: A high efficiency converter for switched reluctance motor (SRM) drive is developed in this paper. In the proposed converter, the power semiconductor device with shorter switching time is employed to implement its high-speed PWM switches. And the soft-switching control is employed for further reducing their switching losses. To achieve this, an auxiliary resonant circuit is added to the PWM switch, and its zero-voltage-transition (ZVT) soft switching is obtained by applying suitable switching signals to the main and auxiliary switches. No extra voltage and/or current sensors are required. Having derived the governing circuit equations, a design procedure is proposed to systematically find the constituted components of the auxiliary branch. As to the low-speed commutation switches, they are realized using the power device having low on-state voltage. Owing to the ability of making PWM switching control, the SRM motor drive with the proposed converter possesses good driving performance. The performance of the designed converter is demonstrated by some simulation and experimental results. An approach for measuring the energy conversion efficiency of a SRM drive is also proposed.

Keywords: Switched reluctance motor (SRM), Soft-switching converter, Zero voltage transition (ZVT), PWM, Efficiency measurement, High-efficiency converter

Title of the Paper:  A New Model for Multi-Objective Load Curtailment Applied on Deregulated Environment


Authors: Sige Liu, Xiaoxin Zhou, Mingtian Fan, Haozhong Cheng

Abstract: In the deregulated environment, transmission congestion is one major problem that needs to be handled in power system operation. This paper aims to alleviate congestion using the multi-objective load curtailment (MOLC) approach. The proposed MOLC approach optimizes the two objectives simultaneous, namely the security margin and load curtailment cost. The security margin is measured by a presented voltage instability indictor (VSI). A fitting coefficient is adopted to combine the two conflicted objectives. The primal dual interior point method (PDIPM) is adopted to solve the proposed MOLC model. The effectiveness of both the improved PDIPM and the MOLC approach has been tested and proven on the modified IEEE 30-bus system and IEEE 118-bus system. The results obtained show that the proposed technique is able to improve system security while yielding lower cost of load curtailment.

Keywords: Multi-objective load curtailment, voltage instability indicator, security margin, cost of load curtailment, fitting coefficient, primal dual interior point method

Issue 6, Volume 8, June 2009

Title of the Paper:  Timing-Driven X-Architecture Routing Tree Construction among Rectangular and Non-Rectangular Obstacles


Authors: Shu-Ping Chang, Hsin-Hsiung Huang, Cheng-Chiang Lin, Tsai-Ming Hsieh

Abstract: In this paper, we formulate a new X-architecture routing problem in presence of non-rectangular obstacles, and propose an X-architecture timing-driven routing algorithm to minimize the maximum source-to-sink delay and the total wirelength simultaneously. First, a spanning graph is constructed by the terminals and the corners of the obstacles. A minimal spanning tree is then produced by performing searching algorithm to the spanning graph. The feasible X-architecture is constructed by transforming all slant edges of the minimal spanning tree. For the initial X-architecture routing tree, the delay of source-to-terminal is estimated by the modified Elmore delay model. According to the user defined delay threshold, an efficient rerouting algorithm is used to fix the timing violated nets. The critical terminals iteratively are rerouted by splitting two sub-trees and merging into one tree. Compared to the routing result without rerouting, the maximum source-to-sink delay is improved by 49.1% and only 2.5% of additional total wirlength is increased.

Keywords: Timing-driven, Non-rectangular obstacle, A-shaped pattern routing, Routing, X-architecture

Title of the Paper:  Performance Curve Fitting to the Operating Point of Fans


Authors: Cheng-Hsing Hsu, Kuang-Yuan Kung, Ching-Chuan Chang, Chia-Chuan Kuo

Abstract: This paper explores utilization of reverse engineering for dimensionless analysis of the performance curve of the fan. Utilizing the function curve and data provided in the reference material, this paper identifies interactions among major parameters affecting the static pressure and flow of the fan. Following the fitting, the equation P(X) is expressed via Chebyshev polynomial. It simplifies the performance curve of the fan to match the impedance curve of the system. The corresponding diagram obtained can be used to predict the operating point of dimensionless performance curve of the fan to match the impedance curve of the system. In comparison with the conventional approach, the operating point of the research method registers an error rate of under 4.97%. This method can help save the cost of experiment or simulation, accelerate the speed of operating point search and reduce the size of the fan databank.

Keywords: Chebyshev polynomial, dimensionless, impedance curve, operating point, reverse engineering, performance curve.

Title of the Paper:  High-SFDR and Multiplierless Direct Digital Frequency Synthesizer


Authors: Tze-Yun Sung, Hsi-Chin Hsin, Lu-Ting Ko

Abstract: This paper presents a hybrid COordinate Rotation DIgital Computer (CORDIC) algorithm for designs and implementations of the direct digital frequency synthesizer (DDFS). The proposed multiplier-less architecture with small ROM (16 ? 4 -bit) and pipelined data path provides a spurious free dynamic range (SFDR) of more than 84.4 dBc. A SoC (System on Chip) has been designed by 0.18μm 1P6M CMOS, and then emulated on the Xilinx FPGA. It is shown that the hybrid CORDIC-based architecture is suitable for VLSI implementations of the DDFS in terms of hardware cost, power consumption, and SFDR.

Keywords: DDFS, hybrid CORDIC, SoC, FPGA, SFDR

Title of the Paper:  Reconfigurable VLSI Architecture for FFT Processor


Authors: Tze-Yun Sung, Hsi-Chin Hsin, Lu-Ting Ko

Abstract: This paper presents a reusable intellectual property (IP) Coordinate Rotation Digital Computer (CORDIC)-based split-radix fast Fourier transform (FFT) core for orthogonal frequency division multiplexer (OFDM) systems, for example, Ultra Wide Band (UWB), Asymmetric Digital Subscriber Line (ADSL), Digital Audio Broadcasting (DAB), Digital Video Broadcasting – Terrestrial (DVB-T), Very High Bitrate DSL (VHDSL), and Worldwide Interoperability for Microwave Access (WiMAX). The high-speed 128/256/512/1024/2048/4096/8192-point FFT processors and programmable FFT processor have been implemented by 0.18μm (1p6m) at 1.8V, in which all the control signals are generated internally. These FFT processors outperform the conventional ones in terms of both power consumption and core area.

Keywords: IP, FFT, CORDIC, split-radix, OFDM systems

Title of the Paper:  Electromagnetic and Thermal Model Parameters of Oil-Filled Transformers


Authors: Nikos E. Mastorakis, Cornelia Aida Bulucea, Marius Constantin Popescu, Gheorghe Manolea, Liliana Perescu-Popescu

Abstract: The study of predictive control of temperature in oil-filled transformers is performed in this work. In order to study transformers thermal loss of life, complex models taking into account electrical and thermal characteristics are required. Moreover, the precision of thermal models is dependent upon the exactitude of the parameters. The work presented in this article shows that, through electromagnetic similitude laws, for an homogeneous series of transformers with different rated powers, the main parameters required for the thermal model can be obtained. Different methodologies to estimate thermal parameters with data from standardised heat-run tests are compared. The foremost advantage of our alternative methodology is its compactness, since parameters are obtained only from the knowledge of transformer rated power. Theoretical results were compared with data from transformer manufacturers and the good agreement between both validates theoretical results is accomplished.

Keywords: Electromagnetic similitude laws, Oil-filled transformers, Temperature control, Thermal parameters

Title of the Paper:  Non-Linear Thermal Model for Transformers Study


Authors: Marius Constantin Popescu, Nikos E. Mastorakis, Cornelia Aida Bulucea, Gheorghe Manolea, Liliana Perescu-Popescu

Abstract: This article begins with a study of transformer additional losses due to the presence of non-sinusoidal loads, presents existing models to represent these losses and proposes an original model. Consequent increment in transformer loss of life is studied by means of a sensitivity analysis of the model to transformer rated power, load amplitude, thermal inertia, profiles correlation and harmonic spectrum content.

Keywords: Transformer model, Non-sinusoidal loads, Thermal parameters

Title of the Paper:  A Design of a Class of Temperature Stabilization System and Implementation


Authors: Shieh-Shing Lin, Shih-Cheng Horng, Hen-Chia Hsu, Jia-Hau Chen, Tseng-Lin Hsieh, Chih-Hao Ho, Kuang-Yao Lin

Abstract: In this paper, we proposed a design for a class of temperature stabilization system based on the feedback control theory and the corresponding technology of microchip MC89C51 and sensors theory. Besides, the proposed design was implemented on a set of temperature control system to determine whether the current status of fishes tank fitting fishes survival or not. Therefore, we can control the temperature of fishes tank. There are three stages in this design. First, we set the temperatures at the fish tank harming fishes life are not suitable for the safety status. Second, we use the MC89C51microprocessor combined with the A/D converter to process the analog measuring temperatures of the sensor measurements into digital data. Finally, a software program was designed to process the obtained digital data and control the solid-state electric relay to increase or decrease the target temperature of the water tank.

Keywords: MC89C51 microprocessor, A/D converter, Digital signals, Sensors, Feedback control theory

Title of the Paper:  Study of Supercapacitor in the Application of Power Electronics


Authors: Yi Cheng Zhang, Li Wei, Xiaojun Shen, Haiquan Liang

Abstract: The purpose of this paper is to carry out a comprehensive study of supercapacitor in the application of power electronics. According to the practical demand and feasibility of power electronics, the modelling, voltage management and topology of supercapacitor-based power system have been discussed. Further more, in order to study the terminal behaviour of supercapacitor and voltage balancing strategy for the application of power electronics, a test bench based on HP-VEE has been built. The measurements on supercapacitor’s capacitance, ESR (Equivalent serial resistance) and the consistency of a group of serial supercapacitors, concerning practical application have been suggested. As an example, Maxwell’s BCAP0120 supercapacitors have been selected for a 1.5kW hybrid supercapacitor- fuel cell power system. Tests have been carried out and the results show that the ESR is higher and the capacitance is lower compared with the values supplied by manufacturers; and the consistency of them is good, thus the voltage initialization strategy can be used for voltage balancing.

Keywords: Supercapacitor, Power Electronics, Voltage-balancing, Capacitance, ESR

Title of the Paper:  Modelling of a SISO and MIMO Non Linear Communication Channel using Two Modelling Techniques


Authors: Nabiha Saidi, Okba Taouali, Hassani Messaoud

Abstract: In this paper, we consider the modelling of a Single Input Single Output (SISO) and Multi Input Multi Output (MIMO) non linear communication channels using two modelling techniques. The first titled Volterra model built using Volterra series and possesses several important properties that make them very useful for the modelling and analysis of non linear systems and the second named RKHS model developed on a particular Hilbert Space the kernel of which is reproducing. This space known as Reproducing Kernel Hilbert Space (RKHS) uses the statistical learning theory to provide RKHS model.The performances of both models in SISO case and in MIMO case are evaluated and the results were successful.

Keywords: Modelling, SISO, MIMO, RKHS, Volterra, communication channel

Title of the Paper:  An Analysis of the Instability Mechanism of a Low - Current Metal Vacuum Arc for Silver Based Cathode Material


Authors: Narong Mungkung, Tanes Tanitteerapan, Somchai Arunrungrusmi, Weerachai Chaokumnerd, Toshifumi Yuji

Abstract: The purpose of this research was to investigate instability phenomena in low-current metal vacuum arc using the calculation data comparison with the experimental data. The instability phenomena are characterized by noise on the current trace prior to the actual current chopping. The instability current was investigated for various electrode materials. A cathode spot model is used to analyze the instability phenomena of vacuum arc. The experiment of major commercial switching electrode such as Ag-Pd is performed in this study. To study the parameters affecting the stability arc factors, the parameter scan of cathode materials and ion current fraction by numerical analysis, it was found that the critical current of the stable current is highly dependent on the thermal conductivity of the cathode material. However, the thermal conductivity effect on the instability phenomena of low-current metal vacuum arc was important for low surge switching electrode material development. An electrostatic probe was used to confirm these findings, and the analytical results were found to be similar to the measurement results. This is very important result for the development of cathode materials for low-surge vacuum interrupters.

Keywords: Cathode spot model, instability, thermal conductivity, silver

Issue 7, Volume 8, July 2009

Title of the Paper:  Nonlinear Feedback System for an Inverter-Based Ring Oscillator


Authors: Chingyei Chung, Shou-Yen Chao, M. F. Lu

Abstract: In integrated circuits, ring oscillator (RO) has many applications. In these applications, how to obtain the accurate oscillation frequency is an important issue for the design. In this paper, we explore the feedback problem of a N-stage ring oscillator. This paper proposes a more rigorous approach to analyze the ring oscillator. It can be approximated that the feedback system of a ring oscillator can be a nonlinear Lur’e problem. With this Lur’e problem, circle criterion can be used to determine the stability of overall feedback system. With this Lur’e problem, he describing-function method is used to determine the oscillation frequency of the ring oscillator. A new formula will be presented. It can be also observed that if N (number of inverters) is large enough, the proposed formula will approach the conventional formula. Moreover, with describing function method, a “necessary condition”for the existence of fundamental mode and higher order modes of oscillations are presented. Furthermore, it can be shown that as N ?7 and the voltage gain is large enough; the higher harmonic oscillation may exists. Finally, with Tsypkin Function method, a more accurate formula for the oscillation frequency of ring oscillator will be presented. Finally, Simulation examples will illustrate these results.

Keywords: Ring oscillator, describing function, Tsypkin function, Extended Nyquist Diagram

Title of the Paper:  A Design Method in CMOS Operational Amplifier Optimization Based on Adaptive Genetic Algorithm


Authors: Jianhai Yu, Zhigang Mao

Abstract: A new method based on adaptive GA(genetic algorithm) for optimizing the parameters of CMOS operational amplifier is presented in this paper. The synthesis of the Op-amp (operational amplifier) can be translated into multiple-objective optimization task, in which a large number of specifications have to be taken into account. Such as DC-gain, bandwidth of unity gain, phase-margin, power, noise and others. The feature of the method is that combining the skills of manual experience of analog circuits design and genetic algorithm, through adjusting the GA with the evolution process, the problems of convergence and multiple objective optimization tasks can be solved; and operational amplifiers for different use can be designed depending on various performance specifications. The results of groups of simulation show that this method can optimize the parameters of analog circuits accurately and efficiently.

Keywords: Genetic algorithm (GA); CMOS analog circuit; operational amplifier; evolution, fitness, sizing

Title of the Paper:  Applying FPGA-based Chip to Apparent Power and Power Factor Measurement Considering Nonsinusoidal and Unbalanced Conditions


Authors: Shu-Chen Wang, Chi-Jui Wu, Sheng-Wen Yang

Abstract: This paper proposes a field-programmable gate array (FPGA)-based integrated circuit (IC) for computing apparent powers and power factors of power systems. In a nonsinusoidal and unbalanced three-phase power system, the calculation of apparent powers and power factors has many definitions. Load characteristics of harmonic and unbalance can not be expressed in the traditional apparent power and power factor, which only consider the fundamental and three-phase balanced sinusoidal conditions. This paper utilizes the FPGA chip to develop the platform to implement the calculation methods of apparent powers and power factors. The proposed design scheme is developed using the very high speed integrated-circuit hardware description language (VHDL), which provides high flexibility and technology independence. This paper discussed the effective power and power factor, the arithmetic power and power factor, and the fundamental power and power factor. The design of filters for the computation of fundamental frequency components is given. ModelSim is used at first to simulate the calculation of apparent powers and power factors to ensure the accuracy of timing and function. Research results show that the designed chip can compute accurately the apparent powers and power factors considering the effects of nonsinusoidal and unbalanced conditions.

Keywords: FPGA, SoC, Power Factor, Harmonic, Unbalanced Power System

Title of the Paper:  Design and Implementation of a System Bus – SPI Bridge for Wireless Radio Prototyping


Authors: Mohamad Yusri Mohamad Yusof, Devi Prasad, Smruti Santosh Palai

Abstract: Prototyping of wireless radio is one of the major stages of the entire development process. It invariably has an interface to the Analog to digital converters (ADC) / Digital to Analog converters (DAC) and RF front end. This paper discusses in detail the design issues and solutions for baseband- RF front end interface, of a wireless radio. In these kinds of systems, the FPGA tends to be connected to the baseband DSP processor through the system bus. The FPGA is then used to implement additional baseband processing, hardware accelerators, ADC/DAC interfaces and RF control, to name a few. The DSP processor will need to communicate with these components through the system bus. Some of these components require high bandwidth and others requires low bandwidth from the system bus. There is a need for a design approach where that avoids slow interfaces, such as RF control interface, from hogging the system bus, which in turn will affect the overall performance of the entire system. This paper presents a System Bus-SPI bridge design approach to mitigate the interfacing issues in wireless system prototyping, especially when the supporting hardware, like RF module, is predefined. The proposed design enables the DSP Processor to access the System Bus concurrently while the SPI programming is in progress. Verilog hardware description language is used to design the System bus –SPI Bridge and Modelsim is used to verify the functionality of the design. The proposed design was implemented on an Altera STRATIX II FPGA.

Keywords: FPGA, SPI, Prototyping, System Bus, Wireless radio, Shared Bus

Title of the Paper:  Multilayer Perceptron and Neural Networks


Authors: Marius-Constantin Popescu, Valentina E. Balas, Liliana Perescu-Popescu, Nikos Mastorakis

Abstract: The attempts for solving linear inseparable problems have led to different variations on the number of layers of neurons and activation functions used. The backpropagation algorithm is the most known and used supervised learning algorithm. Also called the generalized delta algorithm because it expands the training way of the adaline network, it is based on minimizing the difference between the desired output and the actual output, through the downward gradient method (the gradient tells us how a function varies in different directions). Training a multilayer perceptron is often quite slow, requiring thousands or tens of thousands of epochs for complex problems. The best known methods to accelerate learning are: the momentum method and applying a variable learning rate. The paper presents the possibility to control the induction driving using neural systems.

Keywords: Backpropagation algorithm, Gradient method, Multilayer perceptron, Induction driving

Title of the Paper:  Production Techniques of PV's and Polycrystalline PV Performance Analyses for Permanent Resistive Load


Authors: Safak Saglam, Gokhan Kocyigit, Nevzat Onat

Abstract: Photovoltaic (PV) panels which are used to convert solar energy to electrical energy one of the fastest growing source on energy sector. Their efficiencies are increasing day by day with new technologies. Photovoltaic’s average efficiencies are still 15-20% in daily usage. In this study general photovoltaic production techniques are explained briefly. New technological developments affect these production techniques so the new methods on photovoltaic production are examined. During one year period polycrystalline PV performance which feeds the permanent resistive load is tested experimentally for Istanbul-Goztepe.

Keywords: Photovoltaic, D.C. Loads, Energy Consumption, Production Techniques

Title of the Paper:  Digitally Controllable Delay Element Using Switched-Current Mirror


Authors: Sekedi B. Kobenge, Huazhong Yang

Abstract: Controllable delay elements are essential for shifting the edges of signals in many digital and mixed-mode signal processing integrated circuits. Digitally programmable delay elements (DPDEs) are more flexible, less susceptible to noise and exhibit more robustness than their analog counterparts. In this paper, a partially programmable and a fully programmable delay elements are proposed. Together with a switched current mirror, a gate decoupling technique is applied to the former while a Schmitt type inverter is used in the later structure to achieve more significantly reduced static and short-circuit current. The delay elements are implemented in a 0.18um technology and simulation results with a 1V power supply show a more than 40% power saving while operating at a speed of 450MHz in both structures.

Keywords: Current mirror, delay element, inverter, low power, Schmitt trigger, switched current

Title of the Paper:  On-line Partial Discharge Monitoring System and Data Processing Using WTST-NST Filter for High Voltage Power Cable


Authors: Hui Wang, Chengjun Huang, Li Zhang, Yong Qian, Junhua Liu, Linpeng Yao, Canxin Guo, Xiuchen Jiang

Abstract: Defects inside insulation of HV XLPE cable accessories can lead to partial discharge (PD) activity. When PD activity happens, leakage current may flow through the grounded line. To acquire the PD current signal, one practicable and effective method is placing a high frequency current transformer (HFCT) winding the grounded line. In order to measure the insulation degradation, a partial discharge on-line monitoring system is developed and reported in this paper. Through the field test, the presented monitoring system is effective and available for power cable in the condition based maintenance (CBM). However, on-site partial discharger detection on XLPE cables and cable accessories are very difficult of variable noise interference, which gives much trouble to partial discharge detecting. This paper introduced an adaptive filter stationary-non stationary filter based on the wavelet transform (WTST-NST) to de-noise the stationary noise interference in partial discharge detecting. The proposed method is a wavelet domain filtering technique, based on the iterative multi-resolution decomposition reconstruction (MRD-MRR) with hard threshold, for extracting PD signals from stationary interference noise. Quantitative and qualitative analysis of the experimental results, while using the WTST-NST filter to PD signals recorded from power cables, prove that the ability to extract the PD from noise hidden in it.

Keywords: Power cable, Adaptive WTST-NST filter, On-line monitoring, Partial Discharge, MRD-MRR Algorithm, Stationary noise interference, condition based maintenance(CBM)

Title of the Paper:  Studies on Multi-Agent Based Partial Discharge Online Monitoring System for High Voltage Apparatus


Authors: Linpeng Yao, Chengjun Huang, Li Zhang, Yong Qian, Hui Wang, Junhua Liu, Canxin Guo, Xiuchen Jiang

Abstract: In the contribution, the authors applied the Multi-Agent methodology to the partial discharge (PD) online diagnosis for high voltage apparatus, and a PD diagnosis Multi-Agent system for high voltage apparaus was implemented. Based on the investigation of problems existing in partial discharge detection and evaluation, such as preprocessing, features extraction, trend and fingerprint analysis, corresponding methods and schemes were described. The framework of the Multi-Agent system and detailed design of each agent were also depicted. And furthermore, a complete system implemented by Zeus are established for performing evaluation in field application.

Keywords: High voltage, Partial discharge, Multi-Agent, Monitoring, .Net Framework, Zeus

Issue 8, Volume 8, August 2009

Title of the Paper:  Research of Partial Discharge Localization Method in GIS Based on UHF Technique


Authors: Junhua Liu, Ming Yao, Chengjun Huang, Linpeng Yao, Hui Wang, Xiuchen Jiang

Abstract: Some small defects like fix protrusion or free moving particles exist in GIS can induce partial discharge (PD) which will deteriorate insulation condition and eventually cause insulation breakdown when GIS are in service. It is very important to detect and locate the PD signal for early detection of insulation defects and preventing insulation failure. Time of flight method which based on Ultra High Frequency (UHF) technique is widely used for locating PD in GIS for the merits such as simple principle and easy implementation. But in application, the time of flight method can hardly be applied effectively and will induce errors if the initial pulse of the PD signal is small and blurry or its signal-to-noise ratio (SNR) is too low. In this paper, the characteristics of electromagnetic wave (EM-wave) propagation route in GIS were investigated and a new localization method was proposed. The simulation and experiment results show that the EM-wave signals induced by PD in GIS are related with EM-wave propagation routes, which were decided by the location of PD source and detector’s position. The experiment results show that the proposed PD localization method which based on the characteristics of EM-wave propagation route can locate the PD signal well and effectively in the case that the initial pulse of PD signals is very small and blurry when PD source locates near the outer conductor of GIS.

Keywords: GIS, partial discharge, UHF method, localization, EM-wave, propagation route

Title of the Paper:  Design of a Synchronous FFHSS Modulator on a FPGA with System Generator


Authors: Santiago T. Perez, Jesus B. Alonso, Carlos M. Travieso, Miguel A. Ferrer, Jose F. Cruz

Abstract: This work is based on a previous Fast Frequency Hopping Spread Spectrum (FFHSS) transceiver designed for wireless optical communications. The core of the transmitter was a discrete Direct Digital Synthesizer (DDS). In the first prototype the DDS control and the digital synchronization signal were generated using a Programmable Logic Device (PLD), besides a discrete external filter was necessary to eliminate high frequency components of digital synchronization signal and generate analog synchronization signal. The FFHSS and analog synchronization signals were emitted by two separated Light Emitting Diodes (LED) to avoid adding them with discrete analog circuits. The peak emission wavelength of the LED was 650 nanometers. The objective of this work is redesign the modulator on a Field Programmable Gate Array (FPGA) using System Generator from Xilinx and analyse the performances of this design methodology. System Generator is one design tool in Simulink of Matlab. It allows fast design of digital systems using block diagrams. The compilation generates the files necessary for the Integrated System Environment (ISE) for FPGA of Xilinx, where the description of the circuit is obtained in a standard hardware description language. In ISE it is possible to compile the hardware description language files, simulate the system, assign pins, obtain the program file and program the FPGA.

Keywords: Spread spectrum, modulator, DDS, FPGA, System Generator, Xilinx, Simulink, HDL, floating point, fixed point

Title of the Paper:  Assessment of Three-phase Induction Motor Dynamic Regimes Following Ecosystem Patterns


Authors: Nikos E. Mastorakis, Cornelia A. Bulucea, Doru A. Nicola

Abstract: Within the present industrial society the humans further challenges are doubtless related to a sustainable industrial metabolism, integrating industrial activity into ecological systems. An approach of technical systems and ecological systems as parts of the same system, the industrial ecosystem, could provide a holistic view of the interactions and symbiosis interrelationships among human activities, technical systems operation and ecological processes. In this study are pointed the ecosystem key-features suitable for the electrically driven transportation systems analysis. By modeling the electrical traction machines dynamic regimes according to an industrial ecosystem pattern, one could attempt to minimize the environmental impacts and optimize the efficiency of energy use within the transportation systems operation.

Keywords: Dynamic Regimes, Induction Machine, Industrial Ecosystem, Transportation System

Title of the Paper:  Parameters Modelling of Transformer


Authors: Marius-Constantin Popescu, Gheorghe Manolea, Nikos Mastorakis, Liliana Perescu-Popescu

Abstract: This paper analyses transformer loss of life attending to the realistic variability of both structural and functional parameters. The article begins with the modelling of load and ambient temperature profiles, by means of chronological series theory. A simple additive model is proposed and validated with realistic data, loss of life resulting from probabilistic functional and structural parameters is analysed through a sensitivity study.

Keywords: Transformer thermal, Estimate thermal parameters

Title of the Paper:  Network Optimization by Generalized Methodology


Authors: Alexander Zemliak, Ricardo Pena

Abstract: The design process for analog network design is formulated on the basis of the optimum control theory. A special control vector is defined to redistribute the compute expensive between a network analysis and a parametric optimization. This redistribution permits the minimization of a computer time. The problem of the minimal-time network design can be formulated in this case as a classical problem of the optimal control for some functional minimization. The principal difference between the new approach and before elaborated generalized methodology is presented. This difference is based on a higher level of the problem generalization. In this case the structural basis of different design strategies is more complete and this circumstance gives possibility to obtain a great value of computer time gain. Numerical results demonstrate the efficiency and perspective of the proposed approach.

Keywords: Time-optimal design algorithm, control theory formulation, general methodology

Title of the Paper:  Analog Blocks Design Automation


Authors: Hassen Aziza, Annie Perez, Emmanuel Bergeret

Abstract: The purpose of this paper is to present an automated design methodology for analog blocks. This method focuses on analog blocks design parameters automatic generation according to specific design constraints. This method is based on analog circuits’ mathematical models. These models are generated thanks to a “Design Of Experiment” (DOE) technique. The DOE technique takes as input electrical simulation results of a given circuit for different component geometries. DOE generates polynomial equations of the circuits’ outputs. Using these equations and according to given design specifications, the methodology provides the most suitable design parameter values. This efficient methodology reduces extensive simulations to find the right design parameters with respect to circuit accuracy.

Keywords: Analog circuits, design automation, modelling, Charge Pumps (CP), Current References (CR)

Title of the Paper:  Cooperative-PSO-Based PID Neural Network Integral Control Strategy and Simulation Research with Asynchronous Motor Controller Design


Authors: Piao Haiguo, Wang Zhixin, Zhang Huaqiang

Abstract: This paper focuses on the design of robustness controller for asynchronous motor. a new PID neural network-integral (PIDNN-I) synthesis control strategy is proposed for the controller design, in which NARMA-L2, an approximated model of nonlinear auto regressive moving average(NARMA) model, is employed to represent the input-output behavior of the motor and gives out the expected control input. PID neurons network (PIDNN), as a kind of novel neural network model with dynamic characteristics, is adopted in NARMA-L2 to identify the motor. PIDNN integrates the advantages of PID with those of artificial neuron network. However, the conventional back-propagation (BP) algorithm, which easily gets trapped in local minimum and is being adopted in the current model, constrains the identifying ability of PIDNN so as to harm to the completion of the controller design. Particle swarm optimization (PSO) algorithm, a new population-based evolutionary global optimization method, is proposed to replace the BP algorithm to train the neurons model. Cooperative particle swarm optimization (CPSO), an improved version of cooperative random learning particle swarm optimization (CRPSO), is put forward to enhance the performances of the conventional PSO in the design. Due to the existence of the tracking error caused by approximate error between identifying and real system, integral (I) control is introduced into the design, namely adopting PIDNN control in large tracking error scale and PIDNN-I control in small tracking error scale. Compared with conventional PID control strategy, simulation results demonstrate that the CPSO-based PIDNN-I synthesis control strategy has improved the control performances of asynchronous motor in robustness and accuracy efficiently.

Keywords: NARMA-L2, PID neural network, integral, synthesis control, asynchronous motor, BP, PSO, Nonlinear, Cooperative particle swarm optimization

Title of the Paper:  Voltage Control Scheme in Distribution Network with Double Feed Induction Generator Wind Farm


Authors: Jingjing Zhao, Xin Li, Jutao Hao

Abstract: This paper presents the particle swarm optimization (PSO) for reactive power and voltage control (Volt/Var Control) in distribution system considering DFIG wind farm. In this paper, the reactive power output of DFIG wind farm has been considered as the control variables in the Volt/Var Control scheme by considering the reactive power compensation capability of DFIG. The minimization of total system real power loss and voltage deviation are utilized as an objective and the PSO is used to determine the reactive power output of DFIG wind farm, tap positions of load tap changer transformers (LTC) and numbers of the capacitor banks. Finally, the proposed scheme is applied to the 33-node distribution system. The results indicate that the proposed Volt/Var control scheme can improve the voltage profiles of distribution networks on a large scale.

Keywords: Distribution network; DFIG wind turbine; wind farm; Volt/Var Control; particle swarm optimization

Title of the Paper:  Experimental Wavelet Transient-State Analysis of Electrical Machines Directly Feeding by Photovoltaic Cells


Authors: Nevzat Onat, Ismail Kiyak, Gokhan Gokmen

Abstract: Solar electric systems -also known as photovoltaic (PV) systems- have very little impact on the environment, making them one of the cleanest power-generating technologies available. While they're operating, PV systems produce no air pollution, hazardous waste, or noise, and they require no transportable fuels. In PV System design, the selection and proper installation of appropriately-sized components directly affect system reliability, lifetime, and initial cost. The features of the receivers fed from PV systems have a direct impact on the cells; namely, the power generators of the system. System behavior may change in receivers equipped with electrical machines fed from photovoltaic’s, depending on the characteristics of the machine used. The fact that in the design phase of the photovoltaic systems which will feed electrical machines that the current drawn by any electrical machines at the startup is higher than the nominal operating current should be taken into account. In this study, the startup and nominal operating behaviors of electrical machines directly connected to photovoltaic system (not having any storage system or controller system) were empirically examined, obtained power values (in p.u.) were decomposed to sub-frequency components by means of the discrete wavelet transform than they were compared to each others.

Keywords: Photovoltaic Cells, Transient State, Electrical Machines, Wavelet Filter Bank, Multiresolution Analysis

Title of the Paper:  A Reconfigurable FEC System based on Reed-Solomon Codec for DVB and 802.16 Network


Authors: Lamia Chaari, Mohamed Fourati, Nouri Masmoudi, Lotfi Kamoun

Abstract: This article proposes, a reconfigurable FEC system based on Reed-Solomon codec for DVB and WiMax networks. The proposed architecture implements various programmable primitive polynomials. A lot of VLSI implementations have been described in literature. This paper introduces a highly parametrical RS-coder-decoder on FPGAs. The implementation, written in a hardware description language (HDL), is based on an Berlekamp massey, Chain and Formey Algorithms. We have defined an advanced RS encoder-decoder architecture based on parameterization approach which is a key solution for software defined radio (SDR) systems. Our parameterization approach is used in order to implement on FPGA a generic RS coder-decoder for DVB and WiMax networks. IEEE Std. 802.16 specifies that the codec performs a variable number of check symbols in a codeword ( ranges from 0 to 32, inclusive). The value of check symbols are specified for each burst profile by the MAC layer according to cross layer concept.

Keywords: Reedsolomon, Berlekamp massey, Chain, Formey, FPGA, implementation , VHDL, WiMax, DVB

Title of the Paper:  Wind Parks Equivalent Models using System Identification Techniques based on Nonlinear Model Structures


Authors: F. D. Kanellos, G. J. Tsekouras, N. E. Mastorakis

Abstract: In this paper models of Wind Parks (WPs) appropriate for simulation purposes of large power systems with high wind power penetration are developed. The proposed models of the WPs are developed using system identification theory with NARX model structures. Data obtained from the simulation of detailed WP models are used for system identification. The obtained models are general and they can be applied to different configurations of WPs as only system's input/output data are used and not any internal states of the model. Simulation results confirm the accuracy and the advantages of the proposed wind parks equivalent models.

Keywords: Wind parks, wind turbines, modeling, system identification, wind integration

Issue 9, Volume 8, September 2009

Title of the Paper:  New Achievements in Assisted Movement of Visually Impaired in Outdoor Environments


Authors: Ivan Bogdanov, Virgil Tiponut, Radu Mirsu

Abstract: In the last years, the traditional tools used by visually impaired to navigate in real outdoor environments (white cane and guiding dogs) are to be substituted with electronic travel aids (ETA). These devices are capable to improve the mobility of blind users in unknown or dynamically changing environment, but up to date no ETAs have been practically implemented. In this paper, the most important theoretical and practical results obtained in the field of ETAs are presented first. Some original results of the author’s team, including new concepts in this field, like integrated environment for assisted movement, acoustical virtual reality (AVR), bioinspired solutions are then discussed in more detail. Conclusions and the further developments in this area are also presented.

Keywords: Visually impaired individuals, electronic travel aids, integrated environment for assisted movement of visually impaired, acoustical virtual reality

Title of the Paper:  Harmonic-Controlled Three-Way Doherty Amplifier with Improved Linearity


Authors: Natasa Males-Ilic, Aleksandar Atanaskovic, Bratislav Milovanovic

Abstract: In this paper the efficiency and linearity behavior of three-way Doherty amplifier is analyzed. The amplifier is designed in the configuration with two quarter-wave impedance transformers in the output combining circuit with LDMOSFETs in carrier and peaking amplifiers. The signals for linearization (the fundamental signals’ second harmonics-IM2 and fourth-order nonlinear signals-IM4 at frequencies that are close to the second harmonics) are extracted at the output of peaking cells biased at various points. The Doherty amplifier is designed with the frequency diplexer at the outputs of the Doherty cells that separates the fundamental signals and signals for linearization. The diplexer includes harmonic control circuit (HCC) which in combination with matching circuits, provides an optimal impedance for an adequate power level of signals for linearization, and either open circuit for the third harmonics (HCC class-3F) or short circuit for the third harmonics (HCC class-3IF). The linearization technique results in the suppression of the third- and fifth-order intermodulation products of Doherty amplifier.

Keywords: Doherty amplifier, class-F, harmonic control circuit (HCC), linearization, power-added-efficiency, second harmonics, fourth-order nonlinear signals, third- and fifth-order intermodulation products

Title of the Paper:  Modified Direct Torque Control for Single-phase Induction Motor Drives


Authors: Thanatchai Kulworawanichpong, Tawat Chuchit

Abstract: This paper illustrated a modified strategy of direct torque control for single-phase induction motors. The proposed strategy was based on classical six-sector hysteresis-type direct torque control scheme developed by using stator reference frame. The modification made in this paper led to two control strategies called modified six and twelve sectors, respectively. A switching table was derived based on the voltage vectors generated by the three-leg two-phase inverter topology. Simulations were carried out and performance analysis was presented.

Keywords: Single-phase induction motor drives, Direct torque control, Hysteresis control, Six-sector based DTC, Twelve-sector based DTC

Title of the Paper:  Mobile Robot Path Planning using Exact Cell Decomposition and Potential Field Methods


Authors: Dusan Glavaski, Mario Volf, Mirjana Bonkovic

Abstract: In this paper two classic path planning procedures have been explained and adopted to reduce computational time. When studying mobile robotics and robot motion planning, there is always a gap which exists between theoretical achievements and practical considerations of the described methods. This paper clearly overrides the mentioned problem describing minutely the procedures necessary for practical implementations and simulation in the Matlab and MobileSim environment. The algorithms have been presented together with their pseudo codes. The simulation results clearly show the advantages and drawbacks of each of the method.

Keywords: Path planning, mobile robot, exact cell decomposition, potential field

Issue 10, Volume 8, October 2009

Title of the Paper:  Modelling and Simulations of Oil-filled Transformer Loss-of-Life Models


Authors: Marius-Constantin Popescu

Abstract: The purpose of this article is to analyse the tansformer thermal and loss of life models will be studied. Based on the thermal model adopted by International Standards, small improvements to increase model accuracy are presented and a comparative study of resulted accuracy under different load and ambient temperature profiles is performed.

Keywords: Loss of life models, Modelling thermal parameters, Oil-filled transformer

Title of the Paper:  Simulation the Functionality of a Web Cam Image Capture System


Authors: Toadere Florin, Nikos E. Mastorakis

Abstract: The goal of this paper is to imagine the functionality of a web camera image capture system. In order to do that we illuminate a spectral image, we capture the reflected light using an achromatic doublet and finally we focus the light on a CCD. We are interested to see what happens as the image propagates trough the image capture pipeline. We present an illumination algorithm, we design the achromatic doublet, we use an aperture and we compute the CCD transfer function. Using the CCD integration times we take several images in rapid succession, at different exposure levels; then we blend the images in order to obtain a HDR (high dynamic range) image. We consider the image capture system to be axial and the light is orthogonal to the system.

Keywords: Spectral image illumination, achromatic doublet design, CCD transfer function, HDR image, photon shot noise, colors enhancement

Title of the Paper:  Selecting Feature Detectors for Accurate Visual Odometry


Authors: Aldo Cumani, Antonio Guiducci

Abstract: This work analyzes the performances of different feature detectors/descriptors in the context of incremental path estimation from passive stereo vision (Visual Odometry). Several state-of-the-art approaches have been tested, including a fast Hessian-based feature detector/descriptor developed at INRIM. Tests on both synthetic image sequences and real data show that in this particular application our approach yields results of accuracy comparable to the others, while being substantially faster and much more reliable.

Keywords: Robot localisation, Stereo vision, Visual odometry, Feature descriptors, Feature detectors

Title of the Paper:  Parallel Architecture for the Solution of Linear Equations Systems Based on Division Free Gaussian Elimination Method Implemented in FPGA


Authors: R. Martinez, D. Torres, M. Madrigal, S. Maximov

Abstract: This paper presents a parallel architecture for the solution of linear equations systems based on the Division Free Gaussian Elimination Method. This architecture was implemented in a Field Programmable Gate Array (FPGA). The division-free Gaussian elimination method was integrated in identical processors in a FPGA Spartan 3 of Xilinx. A top-down design was used. The proposed architecture can handle IEEE 754 single and double precision floating-point data and the architecture was implemented in 240 processors. Also, an algorithmic complexity of O(n2) was obtained using a n2 processors scheme that perform the solution of the linear equations. Moreover, the parallel division-free Gaussian elimination method, the architecture/s data distribution and the internal processor-element (PE) architecture are presented. Finally, this paper presents the obtained simulation results and synthesis of the modules designed in very high-speed integrated circuit hardware description language (VHDL) using 40 and 100 Mhz frequencies.

Keywords: Field Programmable Gate Array (FPGA), Parallel Processing, Parallel Architectures, linear systems equations, Division Free Gaussian elimination Method

Issue 11, Volume 8, November 2009

Title of the Paper:  A Survey on Modeling and Simulation of a Signal Source with Controlled Waveforms for Industrial Electronic Applications


Authors: Nazih Moubayed, Claude Bayeh, Mouafac Bernard

Abstract: In industrial electronic systems, power converters with power components are used. Each controlled component has its own control circuit. In this paper, the authors propose an original control circuit in order to replace the different existing circuits. The proposed circuit is the representation of an elliptical trigonometry function. Thus, by varying the value of one of its parameter, the output waveform will change. Finally, Labview and Matlab simulation results of the studied circuit are presented and discussed.

Keywords: Power converters, power electronics, power components, mathematics and trigonometry

Title of the Paper:  Transient Characteristics Analysis Based-on Circuit Models for a High-Speed Rail System


Authors: Kuei-Hsiang Chao, Pi-Yun Chen, Chun-Hsin Cheng

Abstract: The main purpose of this study is to analyze the current leakage of the power grid due to the change in speed of high-speed rail (HSR). First, using PSIM software as the fundamental basis, this study constructed an overall HSR circuit-based model system, including Scott transformer, auto-transformer, and the track equivalent circuit and grounding system. In addition, this paper sought to study the current leakage transient responses of a train’s change in speed using this equivalent circuit model. Through simulation results, the study found that the dramatic change in DC voltage from a change in the speed of electric locomotives causes current leakage flowing through the high-speed rail power grid and a rise in ground potential. The study’s analysis results provide possible performance improvements to the high speed rail’s electric locomotives during changes in speed.

Keywords: High-Speed Rail System, Scott Transformer, Leakage Current, Transient Behavior

Title of the Paper:  Charge Equalization Based-on Three-Level NPC Converter for Series Connected Battery Strings


Authors: Kuei-Hsiang Chao, Chia-Chang Hsu, Chun-Hsin Cheng

Abstract: The main purpose of this paper is to design a charge equalization circuit for series connected lead-acid batteries. The charger utilizes a three-level neutral point clamped (NPC) AC/DC converter with voltage balance control to charge the series connected rechargeable battery strings. This paper details the operation principles of the charge equalization circuit under different operation modes and derives the governed equations. The proposed charge equalization circuit can not only regulate the power factor of AC source side, but also can balance the charge voltage for series connected rechargeable batteries. Finally, some simulation results are made to demonstrate the effectiveness of the charge equalization circuit scheme presented in this paper.

Keywords: Lead-Acid Battery, Charge Equalization Circuit, Three-Level Converter, Voltage Balance Control, Neutral Point Clamped (NPC) Converter

Title of the Paper:  Longitudinal Control of Hybrid Electric Buses using Traction Motor and Pneumatic Braking System


Authors: Jie Shu, Yong Zhang, Chengliang Yin

Abstract: Additional energy source of hybrid electric buses comprises new control tasks. One of the main challenges of hybrid electric buses is the integrated control between traction motor and brakes, associated with which is the problem of switching traction motor and brakes. Existing control techniques only provide a result of frequent switch and jerky ride. In this paper, we propose a control strategy including two control laws, which are calculated simultaneously to optimize a certain tracking criterion by a fuzzy adaptive algorithm. Considering parametric uncertainties, the two control laws are used to determine whether to activate the traction motor or the pneumatic brake. The stability and convergence properties of the longitudinal brake control system are analytically proved by using Lyapunov stability theory and Barbalat’s lemma. We examine the proposed algorithm with different mass uncertainties and the simulation results demonstrate stable behaviors when two buses drive into a bus station.

Keywords: Hybrid electric bus; platoon performance; coordinated control; fuzzy adaptive control; sliding mode control

Issue 12, Volume 8, December 2009

Title of the Paper:  Non-Uniform Sampling Delta Modulation-Principles of Parameters Design


Authors: Ryszard Golanski, Jacek Kolodziej, Stanislaw Kuta

Abstract: The parameters design of 1-bit adaptive delta modulations (ADM) systems with uniform sampling rate is well known. Analytical study of delta modulations with sampling rate adaptation have been carried out few years ago. The described ADM systems encode the input signal by changing the sampling intervals and/or step size according to its time-varying slope characteristics. A proposition for design of the parameters of delta modulators with adapting the sampling frequency have been presented. The relation between the boundary values of sampling frequency changes, step size and input power level have been described by the LambertW function. The method presented in this study are useful for parameters design of NS-DM and ANS-DM modulations.

Keywords: Adaptive delta modulation, non-uniform sampling, sampling frequency adaptation, quantization step size, LambertW function

Title of the Paper:  Direction of Sound Wave Arrival Determination Using Time-Delay Estimation and Beamforming Methods


Authors: Petr Dostalek, Vladimir Vasek, Jan Dolinay

Abstract: This paper deals with direction of sound wave arrival determination using time-delay estimation and beamforming methods with utilization of static microphone array with fixed geometry configuration. Theoretical part describes main principle of both methods and possibility of program implementation. Experimental part proposes hardware design of the sensory systems separately for time-delay estimation and beamforming evaluation methods due to different requirements on microphone array structure. Developed localization system is based on standard personal computer equipped with Advantech PCI-1716 multichannel data acquisition device.

Keywords: Audio source localization, microphone array, direction of arrival, time-delay estimation, beamforming, signal processing

Title of the Paper:  On Structure of the Control Vector for Minimal-Time Networks Design Strategy


Authors: Alexander Zemliak, Miguel Torres

Abstract: The generalized methodology for the electronic networks optimization was elaborated by means of the optimal control theory approach. In this case the problem of the electronic system design is formulated as a classical problem of functional minimization of the optimal control theory. The minimal time system design algorithm was defined as a controllable dynamic process with an optimal control vector. By this methodology the aim of the system design process with minimal computer time is presented as a transition process of some dynamic system that has the minimal transition time. The optimal position of the control vector switch points was determined as a principal characteristic of the minimal-time system design algorithm. The special function that is a combination of Lyapunov function of the design process and its time derivative was proposed to predict the optimal control vector to construct an optimal system design algorithm.

Keywords: Minimal-time system design, circuit optimization, control theory application, Lyapunov function

Title of the Paper:  SMES Device Charged by Renewable Energy Used to Regulate Frequency of Interconnected Power System


Authors: Hongmei Li, Zheng Yan, Guoqin Yu, Yi Lin, Kai Niu

Abstract: Development and utilization of renewable energy source (RES) is an important content of global energy development strategy. Being restricted by natural conditions, the output characteristic of renewable energy generation is stochastic. If renewable energy generator units be connected with public grid directly, it will result in the instability of power grid. In this paper, apply wind power as an example, using renewable energy as charge power supply for Superconducting Magnetic Energy Storage (SMES) systems. SMES device possesses some advantages of high efficiency, fast response and good capability of exchange active and reactive power independently with power system. It is a new idea for developing renewable energy. SMES can regulate output depending on load changing on time, which can stabilize fluctuation of frequency and reduce unnecessary power flow among tie lines. Simulation result proved that SMES not only can improve frequency effectively, but also can resolve the defect of inadequate spinning reserve.

Keywords: Renewable energy, SMES, reserve capacity, primary frequency modulation. Automatic generation control (AGC)

Title of the Paper:  An Exponential Family of Hyperbolic–Type Controllers


Authors: Francisco Terneus, Fernando Reyes, Eduardo Lebano

Abstract: This paper addresses the problem of position control for robot manipulators. An Exponential family of Hyperbolic–Type controllers for robot manipulators is presented. The proposed family consists of a large class of control algorithms with nonlinear structure, which incorporates components of hyperbolic type to quickly drive the position error to zero position. We provide explicit sufficient conditions for ensuring directly global asymptotic stability of the closed-loop system composed by the nonlinear robot dynamics for n degrees of freedom and the proposed scheme. Besides the theoretical results, a real-time experimental comparison is also presented to illustrate the performance of the proposed family with other well-known control algorithms such as PD and Hyperbolic Tangent schemes on a three degrees of freedom direct-drive robot arm.

Keywords: Global asymptotic stability, Lyapunov function, PD controller, robot manipulators, position control

Title of the Paper:  Design of a Cascade Planar Transformer for Electrostatic Precipitator Use


Authors: Yan An Wang, Min Hu, Deng Ming Xiao, Yi Min Jiang

Abstract: The traditional high-voltage high-frequency transformer has a drawback of low power density due to the rigorous requirements of high voltage insulation. This paper proposes a new configuration for the magnetic core based on planar EE cores. The parallel connection of planar cores was adopted as a unit, and several units were cascaded to form the high-voltage transformer. The electrical potential distribution of the proposed transformer is more uniform than a traditional transformer, and enables a decrease in the insulation distances. The mechanical configuration of a laboratory prototype is discussed, as well as the electrical, parasitic, and thermal behaviors. A prototype transformer has been designed and built with the following characteristics: 30 kV output voltage, 30 kW output power, and 20 kHz inverting frequency. The transformer was tested and found to have an efficiency of better than 96%. Compared with traditional high-voltage transformers, this transformer has good thermal behavior, good line insulation properties and a high power density.

Keywords: High Voltage, High Frequency, High Power Density, Planar Cores, Cascade Transformer, Insulation

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