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Full-Text Articles in Physical Sciences and Mathematics

Experimental Studies Of A Scaled-Down Tsr-Based Svc And Tcr-Based Svc Prototype For Voltage Regulation And Compensation, Ayetül Gelen, Tankut Yalçinöz Jan 2010

Experimental Studies Of A Scaled-Down Tsr-Based Svc And Tcr-Based Svc Prototype For Voltage Regulation And Compensation, Ayetül Gelen, Tankut Yalçinöz

Turkish Journal of Electrical Engineering and Computer Sciences

In this paper, prototypes of two shunt flexible AC transmission system (FACTS) devices, a thyristor switched reactor (TSR)-based static VAr compensator (SVC) and a thyristor controlled reactor (TCR)-based static VAr compensator- have been developed. The design and testing of both a TSR-based SVC and a TCR-based SVC are accomplished in the Power Systems Research Laboratory of Nigde University. The TSR-based SVC and TCR-based SVC devices are studied in three-bus and single machine infinite bus systems for three-phase static load conditions. The effects of TSR-based SVC and TCR-based SVC devices on load voltages are also analyzed. Experimental results show that significant …


An Rfid Based Indoor Tracking Method For Navigating Visually Impaired People, Ruşen Öktem, Eli̇f Aydin Jan 2010

An Rfid Based Indoor Tracking Method For Navigating Visually Impaired People, Ruşen Öktem, Eli̇f Aydin

Turkish Journal of Electrical Engineering and Computer Sciences

This paper tackles the RFID based tracking problem in an obscured indoor environment. The proposed solution is an integral part of a navigation aid for guiding visually impaired people in a store. It uses RF signal strengths and is based on the Bayes Decision Theory. An observation vector is formed by received radio signal strength indication values, transmitted from three transmitters at distinct frequencies in the UHF band. The indoor area is divided into square grids, where each grid is considered as a class. The problem of tracking is expressed as classifying the observed radio signal strengths to the most …


Oceanography Radar System Wera: Features, Accuracy, Reliability And Limitations, Thomas Helzel, Matthias Kniephoff, Leif Petersen Jan 2010

Oceanography Radar System Wera: Features, Accuracy, Reliability And Limitations, Thomas Helzel, Matthias Kniephoff, Leif Petersen

Turkish Journal of Electrical Engineering and Computer Sciences

The WERA system (WavE RAdar) is a shore based remote sensing system to monitor ocean surface currents, waves and wind direction. This long range, high resolution monitoring system based on short radio wave radar technology. The vertical polarised electromagnetic wave is coupled to the conductive ocean surface and follows the curvature of the earth. This over the horizon oceanography radar can pick up back-scattered signals from the rough ocean surface (Bragg effect) from ranges of up to 200 km. The physical background, technical concept and environmental boundary conditions are explained. Results for various installations from all over the world demonstrates …


Modeling And Simulation Strategies In High Frequency Surface Wave Radars, Levent Sevgi̇ Jan 2010

Modeling And Simulation Strategies In High Frequency Surface Wave Radars, Levent Sevgi̇

Turkish Journal of Electrical Engineering and Computer Sciences

Surface Wave High Frequency Radars (SWHFR) are taken into account in the content of modeling and simulation challenges. Examples related to multi-mixed path surface wave propagation, radar cross section (RCS) prediction, and total radar echo showing target, clutter, noise, and interference are presented.


Implementation Of Method For Operating Multiple High Frequency Surface Wave Radars On A Common Carrier Frequency, Ryan Riddolls Jan 2010

Implementation Of Method For Operating Multiple High Frequency Surface Wave Radars On A Common Carrier Frequency, Ryan Riddolls

Turkish Journal of Electrical Engineering and Computer Sciences

The increasing use of High Frequency Surface Wave Radar (HFSWR) for the surveillance of coastal regions is faced with the problem of limited channel availability in the electromagnetic spectrum. Thus, there is a need for multiple radars to share a common frequency channel. Proof-of-concept work is presented here for a method to operate multiple radar systems on a common carrier frequency. A review is provided of an existing concept where a common waveform is modulated by tones varying by a few hertz across the different radars. The signals from the different radars are separated by either pulse-domain filtering or Doppler …


Securing Fuzzy Vault Schemes Through Biometric Hashing, Cengi̇z Örenci̇k, Thomas Brochmann Pedersen, Erkay Savaş, Mehmet Keski̇nöz Jan 2010

Securing Fuzzy Vault Schemes Through Biometric Hashing, Cengi̇z Örenci̇k, Thomas Brochmann Pedersen, Erkay Savaş, Mehmet Keski̇nöz

Turkish Journal of Electrical Engineering and Computer Sciences

The fuzzy vault scheme is a well-known technique to mitigate privacy, security, and usability related problems in biometric identification applications. The basic idea is to hide biometric data along with secret information amongst randomly selected chaff points during the enrollment process. Only the owner of the biometric data who presents correct biometrics can recover the secret and identify himself. Recent research, however, has shown that the scheme is vulnerable to certain types of attacks. The recently proposed ``correlation attack'', that allows linking two vaults of the same biometric, pose serious privacy risks that have not been sufficiently addressed. The primary …


Corrective Action Planning Considering Facts Allocation And Optimal Load Shedding Using Bacterial Foraging Oriented By Particle Swarm Optimization Algorithm, Rahmat Allah Hooshmand, Mostafa Ezatabadi Jan 2010

Corrective Action Planning Considering Facts Allocation And Optimal Load Shedding Using Bacterial Foraging Oriented By Particle Swarm Optimization Algorithm, Rahmat Allah Hooshmand, Mostafa Ezatabadi

Turkish Journal of Electrical Engineering and Computer Sciences

Reactive power planning (RPP) involves optimal allocation and determination of the type and size of new reactive power (VAR) supplies to satisfy voltage constraints during normal and contingency states. The RPP issue is in fact an optimization of large scale mixed integer nonlinear programming problem, so it is proper to use an evolutionary algorithm to solve the problem. In this paper, in order to solve the RPP problem for corrective action of power systems, the bacterial foraging (BF) oriented by particle swarm optimization (PSO) algorithm (BF-PSO) is proposed. In the algorithm, the VAR control has been carried out by using …


Adaptive Neuro-Fuzzy Inference System To Improve The Power Quality Of Variable-Speed Wind Power Generation System, Yüksel Oğuz, Kami̇l Ri̇fat İrfan Güney Jan 2010

Adaptive Neuro-Fuzzy Inference System To Improve The Power Quality Of Variable-Speed Wind Power Generation System, Yüksel Oğuz, Kami̇l Ri̇fat İrfan Güney

Turkish Journal of Electrical Engineering and Computer Sciences

In this study, an adaptive neuro-fuzzy inference system is designed for output voltage and frequency control of a variable-speed wind power generation system. Variable-speed wind power generation systems (VSWPGS) provide the opportunity to capture more power than fixed speed turbines. On the other hand, the variable-speed wind turbine output can be variable voltage and variable frequency for fluctuating wind speeds. The quality of output power can be improved if adequate controls are incorporated in the system. To bring the output voltage and frequency of system by means of control of blade pitch angle of wind turbine to a desirable value, …


The Analysis Of A Semiconductor Single Asymmetric And Symmetric Step-Index Laser For Even And Odd Fields By Alpha Method, Mustafa Temi̇z, Mehmet Ünal Jan 2010

The Analysis Of A Semiconductor Single Asymmetric And Symmetric Step-Index Laser For Even And Odd Fields By Alpha Method, Mustafa Temi̇z, Mehmet Ünal

Turkish Journal of Electrical Engineering and Computer Sciences

In this work, semiconductor step-index single waveguide has been analyzed by Alpha Method. A requested quantity of wave guide can be obtained in terms of normalized propagation constant, which is represented by alpha belonging to active region. Based on this method, structural properties of the material containing any requested quantity of the waveguide is theoretically calculated, when the width of the active region, the refractive indices of the regions and the wavelength are given. In the TE mode some important parameters, such as the propagation constants for regions of the semiconductor step-index single waveguide, the wave numbers, the effective index …


Fractional Order Sliding Mode Control With Reaching Law Approach, Mehmet Önder Efe Jan 2010

Fractional Order Sliding Mode Control With Reaching Law Approach, Mehmet Önder Efe

Turkish Journal of Electrical Engineering and Computer Sciences

Fractional order sliding mode control is studied in this paper. The control objectives are achieved by adopting the reaching law approach of sliding mode control. The main contribution of this work is to show that the philosophy of integer order sliding mode control is valid also for the systems represented by fractional order operators. A sufficient condition and its implications for stability are given. Matched and unmatched uncertainties are studied. The attractor nature of the switching manifold is analyzed together with a stable sliding subspace design condition. The claims are justified through a set of simulations and the results obtained …


A Novel Algorithm For Sensorless Motion Control Of Flexible Structures, Islam Shoukry Mohammed Khalil, Emrah Deni̇z Kunt, Asif Sabanovic Jan 2010

A Novel Algorithm For Sensorless Motion Control Of Flexible Structures, Islam Shoukry Mohammed Khalil, Emrah Deni̇z Kunt, Asif Sabanovic

Turkish Journal of Electrical Engineering and Computer Sciences

This article demonstrates the validity of using an actuator as a single platform for measurements during a motion control assignment of flexible systems kept free from any kind of measurement. System acceleration level dynamics, parameters and interaction forces with the environment are coupled in an incident reaction torque that naturally rises when a flexible system is subjected to an action imposed by an attached actuator to the system. This work attempts to decouple each of the system parameters out of the incident coupled reaction torque at the interface point of the actuator with the flexible system by way of measurements …


Modeling And Control Of Flow Problems By Adaptation-Based Linear Parameter Varying Models, Coşku Kasnakoğlu Jan 2010

Modeling And Control Of Flow Problems By Adaptation-Based Linear Parameter Varying Models, Coşku Kasnakoğlu

Turkish Journal of Electrical Engineering and Computer Sciences

In this paper a systematic modeling and control approach for flow problems is considered. A nonlinear Galerkin model is obtained from the partial differential equations (PDEs) describing the flow; and a Linear Parameter Varying (LPV) model is constructed to approximate the Galerkin model, where the parameter variation of the LPV model is controller by an adaptation mechanism. The LPV model is then treated as a surrogate on which the control design is carried out, where the parameter variations provide a range of uncertainty in which the control design must perform satisfactorily. It is shown that if certain conditions are met, …


Experimental Investigation Of Shaft Transducerless Speed And Position Control Of Ac Induction And Interior Permanent Magnet Motors, Ömer Göksu, Ahmet Masum Hava Jan 2010

Experimental Investigation Of Shaft Transducerless Speed And Position Control Of Ac Induction And Interior Permanent Magnet Motors, Ömer Göksu, Ahmet Masum Hava

Turkish Journal of Electrical Engineering and Computer Sciences

In order to drive AC motors with high efficiency and high motion performance, and to provide accurate speed/position control, motor shaft speed and/or position feedback is required. For this purpose, usually transducers (encoder, tachogenerator, resolver, etc.) are installed on the shaft. However, transducers are not preferred in most of the applications since they increase the cost and decrease the reliability of the drive due to their failure prone structure and connections. In such applications, the speed and/or position information of the motor is obtained by estimation methods without using shaft transducers. In this work, motor types and speed/position estimation methods …


Direct Discrete-Time Control Of Port Controlled Hamiltonian Systems, Yaprak Yalçin, Leyla Gören Sümer Jan 2010

Direct Discrete-Time Control Of Port Controlled Hamiltonian Systems, Yaprak Yalçin, Leyla Gören Sümer

Turkish Journal of Electrical Engineering and Computer Sciences

The direct discrete time control of Port Controlled Hamiltonian Systems (PCHS) in the sense of energy shaping and damping injection is considered. In order to give a direct discrete time design method for PCHS, firstly an appropriate discrete gradient is proposed, which enables the derivation of a discrete time equation corresponding to the discrete time counterpart of Hamiltonian Systems. Using this proposed discrete-time model, the discrete-time counterpart of Passivity Based Control (PBC) technique is developed for n-degrees-of-freedom mechanical systems. The discrete-time control rules which correspond to the energy shaping and damping assignment are obtained directly using the discrete time model …


The Use Of Fpga In Field-Oriented Control Of An Induction Machine, Özkan Akin, İrfan Alan Jan 2010

The Use Of Fpga In Field-Oriented Control Of An Induction Machine, Özkan Akin, İrfan Alan

Turkish Journal of Electrical Engineering and Computer Sciences

In this study, the feasibility of embedding the field oriented control (FOC) of an induction machine into field programmable gate arrays (FPGA) is investigated. An indirect FOC of an induction machine is simulated in a Matlab Simulink environment using a Xilinx System Generator implemented in a Xilinx Spartan-3 XC3S200 FPGA board. Design of the developed controller for the induction machine is simulated via a Simulink full digital platform. The resulting design has a flexible and modular structure where the designer can customize the hardware blocks by changing the number of inputs, outputs, and algorithm when it is compared to the …


Fuzzy Adaptive Neural Network Approach To Path Loss Prediction In Urban Areas At Gsm-900 Band, Türkan Erbay Dalkiliç, Berna Yeşi̇m Hanci, Ayşen Apaydin Jan 2010

Fuzzy Adaptive Neural Network Approach To Path Loss Prediction In Urban Areas At Gsm-900 Band, Türkan Erbay Dalkiliç, Berna Yeşi̇m Hanci, Ayşen Apaydin

Turkish Journal of Electrical Engineering and Computer Sciences

This paper presents the results of the Adaptive-Network Based Fuzzy Inference System (ANFIS) for the prediction of path loss in a specific urban environment. A new algorithm based ANFIS for tuning the path loss model is introduced in this work. The performance of the path loss model which is obtained from proposed algorithm is compared to the Bertoni-Walfisch model, which is one of the best studied for propagation analysis involving buildings. This comparison is based on the mean square error between predicted and measured values. According to the indicated error criterion, the errors related to the predictions that are obtained …


Behaviors Of Real-Time Schedulers Under Resource Modification And A Steady Scheme With Bounded Utilization, Refi̇k Samet, Orhan Fi̇kret Duman Jan 2010

Behaviors Of Real-Time Schedulers Under Resource Modification And A Steady Scheme With Bounded Utilization, Refi̇k Samet, Orhan Fi̇kret Duman

Turkish Journal of Electrical Engineering and Computer Sciences

In this article we present an analysis for task models having random resource needs and different arrival patterns. In hard real-time environments like avionic systems or nuclear reactors, the inputs to the system are obtained from real world by using sensors. And it is highly possible for a task to have different resource needs for each period according to these changing conditions of real world. We made an analysis of schedulers for task models having random resources in each period. Since feasibility tests for usual task models are just limited to some specific schedulers and arrival patterns, we made our …


A Novel Ep Approach For Multi-Area Economic Dispatch With Multiple Fuel Options, P. S. Manoharan, P. S. Kannan, V. Ramanathan Jan 2009

A Novel Ep Approach For Multi-Area Economic Dispatch With Multiple Fuel Options, P. S. Manoharan, P. S. Kannan, V. Ramanathan

Turkish Journal of Electrical Engineering and Computer Sciences

This paper presents a novel approach to multi-area economic dispatch problems with multiple fuel options using a hybrid evolutionary programming method. The objective is to minimize the operation cost of the entire system while satisfying the tie line constraints. In this paper, EP-LMO (Evolutionary Programming with Levenberg-Marquardt Optimization) technique is proposed to solve multi-area economic dispatch problems with multiple fuel options. The EP-LMO is developed in such a way that a simple evolutionary programming (EP) is applied as a base level search to find the direction of the optimal global region. And Levenberg-Marquardt Optimization (LMO) method is used as a …


Modeling And Calculation Of Electromagnetic Field In The Surroundings Of A Large Power Transformer, Leonardo Strac, Franjo Kelemen, Damir Zarko Jan 2009

Modeling And Calculation Of Electromagnetic Field In The Surroundings Of A Large Power Transformer, Leonardo Strac, Franjo Kelemen, Damir Zarko

Turkish Journal of Electrical Engineering and Computer Sciences

The presented study compares measured and calculated electromagnetic field quantities in the surroundings of a large power transformer with the aim to avoid the necessity of measuring the field on subsequent units and use a computer model instead. The influences of various objects located in the vicinity of the transformer during measurement are also analyzed and are taken into account in a computer model.


Analytical Regularization Method For Electromagnetic Wave Diffraction By Axially Symmetrical Thin Annular Strips, Fati̇h Di̇kmen, Yury Alexanderovich Tuchkin Jan 2009

Analytical Regularization Method For Electromagnetic Wave Diffraction By Axially Symmetrical Thin Annular Strips, Fati̇h Di̇kmen, Yury Alexanderovich Tuchkin

Turkish Journal of Electrical Engineering and Computer Sciences

A new mathematically rigorous and numerically efficient method based on the combination of Orthogonal Polynomials Method, and Analytical Regularization Method, for electromagnetic wave diffraction by a model structure for various antennae such as Fresnel zone plates is proposed. It can be used as validation tool for the other (more general or less accurate) numerical methods and physical approaches. The initial boundary value problem is equivalently reduced to the infinite system of the linear algebraic equations of the second kind, i.e. to an equation of the type (I+H) x=b in the space l_2 with compact operator H. This equation can be …


Polymorphic Worm Detection Using Strong Token-Pair Signatures, Burak Bayoğlu, İbrahi̇m Soğukpinar Jan 2009

Polymorphic Worm Detection Using Strong Token-Pair Signatures, Burak Bayoğlu, İbrahi̇m Soğukpinar

Turkish Journal of Electrical Engineering and Computer Sciences

Malicious software has become a big threat to information systems, which are widely used to store, transfer and process information for many critical assets. Worms are one of the most harmful network-enabled malicious software that can threaten networks and applications. Two main characteristics of worms distinguish them from the well-known virus programs and as a result are much more dangerous than the virus programs. First, they do not need to attach themselves to an existing program. Second, worms do not require end-user interaction to realize the intended attack. Therefore, a large number of victims can be infected in a short …


Cdm Based Controller Design For Nonlinear Heat Exchanger Process, Erkan İmal Jan 2009

Cdm Based Controller Design For Nonlinear Heat Exchanger Process, Erkan İmal

Turkish Journal of Electrical Engineering and Computer Sciences

Most processes are nonlinear, and their control is a difficult yet important problem. The heat exchanger is an example onesuch nonlinear process. In the present paper, the effect of process nonlinearity on the performance of set point tracking and disturbance rejection in two controller methods is investigated. Initially, afirst order plus dead time (FOPDT) model of the process is obtainedvia a software known as Loop-Pro Trainer. Then, the PI-controller tuning values are computed using the internal model control (IMC) correlations based on truncated (first-order) Taylor series approximation. Next, another controller is designed using the coefficient diagram method (CDM). Finally, the …


Construction And Applications Of The Dirichlet-To-Neumann Operator In Transmission Line Modeling, Thomas Demeester, Daniel De Zutter Jan 2009

Construction And Applications Of The Dirichlet-To-Neumann Operator In Transmission Line Modeling, Thomas Demeester, Daniel De Zutter

Turkish Journal of Electrical Engineering and Computer Sciences

The Dirichlet-to-Neumann (DtN) operator is a useful tool in the characterization of interconnect structures. In combination with the Method of Moments, it can be used for the calculation of the per-unit length transmission line parameters of multi-conductor interconnections, or to directly determine the internal impedance of conductors. This paper presents a new and fast calculation method for the DtN boundary operator in the important case of rectangular structures, based on the superposition of parallel-plate waveguide modes. Especially for its non-differential form, some numerical issues need to be addressed. It is further explained how the DtN operator can be determined for …


Variance And Kurtosis-Based Characterization Of Resonances In Stochastic Transmission Lines: Local Versus Global Random Geometries, Ousmane Sy, Martijn Van Beurden, Bastiaan Michielsen, Antonius Tijhuis Jan 2009

Variance And Kurtosis-Based Characterization Of Resonances In Stochastic Transmission Lines: Local Versus Global Random Geometries, Ousmane Sy, Martijn Van Beurden, Bastiaan Michielsen, Antonius Tijhuis

Turkish Journal of Electrical Engineering and Computer Sciences

A stochastic method is proposed to characterize electromagnetic couplings involving geometrically perturbed transmission lines. A combined exploitation of suitably defined statistical tools is presented to appreciate the intensity of the dispersion of response variables both physically via the variance, and statistically through the kurtosis or fourth-order moment. The usefulness of this method to analyze resonances is illustrated by the study of a transmission line affected by two different types of random geometrical perturbations, viz. a local deformation modeled by a wavelet and global sinusoidal undulations.


Emc Education At The University Of Technology Zurich, Gökhan Apaydin, Ni̇yazi̇ Ari Jan 2009

Emc Education At The University Of Technology Zurich, Gökhan Apaydin, Ni̇yazi̇ Ari

Turkish Journal of Electrical Engineering and Computer Sciences

This paper illustrates educational issues in electromagnetic compatibility (EMC) engineering in Switzerland and presents the contents of courses and practical materials for EMC education at the University of Technology Zurich. After giving the fundamentals of theoretical part, practical applications have been given to make students and engineers aware of EMC issues and its problems.


Electromagnetic Compatibility Engineering Education: Problems, Challenges And Perspectives, Levent Sevgi̇ Jan 2009

Electromagnetic Compatibility Engineering Education: Problems, Challenges And Perspectives, Levent Sevgi̇

Turkish Journal of Electrical Engineering and Computer Sciences

Education and training problems and challenges in EMC Engineering are discussed. The necessity of physics-based modeling (theory) and hands-on training (practice) are emphasized. An introductory level EMC lecture and a short course outline are given for modern EMC education.


Conductive Emi Noise Measurement For Switched Reluctance Drive, Hao Chen, Xiaohui Qiu, Yang Zhao Jan 2009

Conductive Emi Noise Measurement For Switched Reluctance Drive, Hao Chen, Xiaohui Qiu, Yang Zhao

Turkish Journal of Electrical Engineering and Computer Sciences

The component parts of the tested four-phase Switched Reluctance drive are described with the four-phase 8/6 structure double salient reluctance motor, the four-phase asymmetric bridge power converter and the 89C52 MCU digital controller. The conductive electromagnetic interference noise measurement equipment is described with the function of separated common-mode noise and differential-mode noise. The tested results of common-mode noise and differential-mode noise of the tested Switched Reluctance drive are presented and the tested results of frequency spectrum are given.


Experimantal Characterization And Equivalent Circuit Extraction Of Nanowires For Signal Integrity Applications, Giulio Antonini, Marco Di Clerico, Antonio Orlandi, Vittorio Ricchiuti, Maurizio Passacantando, Sandro Santucci Jan 2009

Experimantal Characterization And Equivalent Circuit Extraction Of Nanowires For Signal Integrity Applications, Giulio Antonini, Marco Di Clerico, Antonio Orlandi, Vittorio Ricchiuti, Maurizio Passacantando, Sandro Santucci

Turkish Journal of Electrical Engineering and Computer Sciences

This paper illustrates the design steps of a printed circuit board used as test vehicles for the measurement of the electrical properties of carbon nanotube's deposit. The board has been built and used for the measurements. The measured data are post-processed in order to extract the required properties of the only nanotubes. An equivalent circuit is extracted for further use in EDA simulators and the IEEE P1597 Standard is used to compare the results.


Two Dimensional Ebg Structures For Multiband Noise Mitigation, Antonio Orlandi, Antonio Ciccomancini Jan 2009

Two Dimensional Ebg Structures For Multiband Noise Mitigation, Antonio Orlandi, Antonio Ciccomancini

Turkish Journal of Electrical Engineering and Computer Sciences

In this paper a two dimensional (2D) electromagnetic Bandgap (EBG) structure is proposed for multi band noise mitigation in PWR/GND plane pairs. Excellent noise suppression (-60 dB) is achieved in multiple bands within the range 0--8 GHz with a low start frequency. Because of the 2D EBG, no additional metal layer is required. Signal Integrity analysis is also studied by modelling a microstrip to stripline transition (both single ended and differential) and by evaluating insertion loss, TDR as well as eye diagram.


Electromagnetic Radiation From Multilayer Printed Circuit Boards: A 3d Fdtd-Based Virtual Emission Predictor, Gonca Çakir, Mustafa Çakir, Levent Sevgi̇ Jan 2009

Electromagnetic Radiation From Multilayer Printed Circuit Boards: A 3d Fdtd-Based Virtual Emission Predictor, Gonca Çakir, Mustafa Çakir, Levent Sevgi̇

Turkish Journal of Electrical Engineering and Computer Sciences

A novel FDTD-based virtual electromagnetic compatibility tool for the prediction of electromagnetic emissions from a multilayer printed circuit board is introduced. Tests are performed with characteristic structures and sample simulation results are presented.