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Full-Text Articles in Computer Engineering

Sequence Alignment From The Perspective Of Stochastic Optimization: A Survey, İhsan Ömür Bucak, Volkan Uslan Jan 2011

Sequence Alignment From The Perspective Of Stochastic Optimization: A Survey, İhsan Ömür Bucak, Volkan Uslan

Turkish Journal of Electrical Engineering and Computer Sciences

DNA and protein are the fundamental biological sequences. DNA is a fundamental molecule that plays a vital role in the processes of life. Proteins synthesized by DNA in a cell are the building blocks of every living organism. There is a variety of reasons behind the alignment of biological sequences. Biological sequence alignment helps to discover functional and structural similarity of sequences. Biologists work with these aligned sequences to construct phylogenetic trees, characterize protein families, and predict protein structure. Sequence alignment is an extremely promising field of research that is characterized by very high computational complexity. Stochastic optimization is needed …


Papr Reduction Using Artificial Bee Colony Algorithm In Ofdm Systems, Necmi̇ Taşpinar, Dervi̇ş Karaboğa, Mahmut Yildirim, Bahri̇ye Akay Jan 2011

Papr Reduction Using Artificial Bee Colony Algorithm In Ofdm Systems, Necmi̇ Taşpinar, Dervi̇ş Karaboğa, Mahmut Yildirim, Bahri̇ye Akay

Turkish Journal of Electrical Engineering and Computer Sciences

Partial transmit sequence (PTS) is an attractive scheme for peak-to-average power ratio (PAPR) reduction in orthogonal frequency division multiplexing (OFDM) systems, but its high computational complexity to find optimum phase factors is the main drawback. In this paper, we propose PTS based on an artificial bee colony (ABC) algorithm (ABC-PTS) for reducing the computational complexity of the PTS in the OFDM system. The ABC-PTS was compared to conventional PTS using a random search strategy (RS-PTS) and optimum PTS. In addition, the bit error rate (BER) performance of the ABC-PTS was shown when a high power amplifier (HPA) was used for …


Simulation Of Storage Time Versus Reverse Bias Current For P^+N And Pin Diodes, Mehmet Serhat Keserli̇oğlu, Hasan Hüseyi̇n Erkaya Jan 2011

Simulation Of Storage Time Versus Reverse Bias Current For P^+N And Pin Diodes, Mehmet Serhat Keserli̇oğlu, Hasan Hüseyi̇n Erkaya

Turkish Journal of Electrical Engineering and Computer Sciences

In this study, the reverse-recovery behaviors of pin and p^+n diodes were simulated as a function of the reverse current and carrier lifetime. For this purpose, a 1-D simulation program was written to solve the semiconductor equations. MatLab partial differential equation solver was used. The reverse recovery response of pin and p^+n diodes was obtained for various values of a resistor in series and of carrier lifetime. The transient response for voltage and current was determined.


A New Lvi Assisted Psfb Dc-Dc Converter, Ahmet Faruk Bakan Jan 2011

A New Lvi Assisted Psfb Dc-Dc Converter, Ahmet Faruk Bakan

Turkish Journal of Electrical Engineering and Computer Sciences

In this study, a new Phase Shifted Full Bridge (PSFB) Pulse Width Modulated (PWM) isolated dc-dc converter is proposed. In the proposed converter, resonant inductor is replaced with Linear Variable Inductor (LVI) that is controlled by output current. The soft switching operation range is increased and the dependency of ZVS operation on the load current is decreased. The required energy for ZVS operation at low current levels is obtained by means of the high value of the LVI. The value of LVI decreases approximately linearly with increasing current. At high current levels parasitic resonance and duty cycle loss are decreased. …


Electromagnetic Scattering From Layered Strip Geometries: The Method Of Moments Study With The Sinc Basis, Taner Oğuzer, Fadil Kuyucuoğlu, İbrahi̇m Avgin Jan 2011

Electromagnetic Scattering From Layered Strip Geometries: The Method Of Moments Study With The Sinc Basis, Taner Oğuzer, Fadil Kuyucuoğlu, İbrahi̇m Avgin

Turkish Journal of Electrical Engineering and Computer Sciences

Electromagnetic scattering from strips of layers is analyzed using the method of moments (MoM) for both polarizations in spatial domain with the sinc-type orthogonal sets as basis and testing functions. We exploited the sinc function's properties of exponential convergence, the orthogonality, easy convolution and better handling of singular kernels in MoM procedure resulting in fast performance and reasonable accuracy even in ordinary MoM treatment. We transferred the integral of the Hankel function multiplied by sinc functions to Hankel function introducing a slight error with large band width. We proved that this relative error during the generation of the main matrix …


Vibrations Control Of Light Rail Transportation Vehicle Via Pid Type Fuzzy Controller Using Parameters Adaptive Method, Muzaffer Meti̇n, Rahmi̇ Güçlü Jan 2011

Vibrations Control Of Light Rail Transportation Vehicle Via Pid Type Fuzzy Controller Using Parameters Adaptive Method, Muzaffer Meti̇n, Rahmi̇ Güçlü

Turkish Journal of Electrical Engineering and Computer Sciences

In this study, a conventional PID type fuzzy controller and parameter adaptive fuzzy controller are designed to control vibrations actively of a light rail transport vehicle which modeled as 6 degree-of-freedom system and compared performances of these two controllers. Rail vehicle model consists of a passenger seat and its suspension system, vehicle body, bogie, primary and secondary suspensions and wheels. The similarity between mathematical model and real system is shown by comparing uncontrolled simulation results and vibration measurements. For carrying a comfortable travel, rail vehicle body and passenger seat vibrations are minimized by adding a controller between rail vehicle body …


A Stationary, Variable Dof Flight Control System For An Unmanned Quadrocopter, Vasfi̇ Emre Ömürlü, Ahmet Kirli, Utku Büyükşahi̇n, Şeref Naci̇ Engi̇n, Sedat Kurtoğlu Jan 2011

A Stationary, Variable Dof Flight Control System For An Unmanned Quadrocopter, Vasfi̇ Emre Ömürlü, Ahmet Kirli, Utku Büyükşahi̇n, Şeref Naci̇ Engi̇n, Sedat Kurtoğlu

Turkish Journal of Electrical Engineering and Computer Sciences

Unmanned air vehicles (UAV) and especially quadrocopters have drawn great attention in recent years because of their maneuverability and nonlinear control problem. Most of the related research concentrate on control; yet, design and communication are also some sub-topics. In this paper, a stationary, four rotor air vehicle with limited/controlled degree of freedom is constructed so that various control algorithms and their changing effects with varying vehicle dynamics can be studied on the ground for safety purposes. Ascending/descending, pitch/yaw/roll motions can be limited by setting the vehicle's degree of freedom mechanically, resulting better net observability of the control algorithms on the …


A Luenberger-Sliding Mode Observer With Rotor Time Constant Parameter Estimation In Induction Motor Drives, Mustafa Gürkan Aydeni̇z, İbrahi̇m Şenol Jan 2011

A Luenberger-Sliding Mode Observer With Rotor Time Constant Parameter Estimation In Induction Motor Drives, Mustafa Gürkan Aydeni̇z, İbrahi̇m Şenol

Turkish Journal of Electrical Engineering and Computer Sciences

The performance and efficiency of an induction motor drive system can be enhanced by online estimation of critical parameters such as rotor time constant. A novel Luenberger-sliding mode observer with a parameter adaptation algorithm is proposed in this paper to compensate for the parameter variation effects. The observer is comparably simple and robust relative to the previously developed observers, and yet suitable for online implementation. Simulation studies for the proposed method were conducted in a MATLAB environment. Observer constants and the control parameters were tuned during the simulation studies and used during the experimental study stage. Experimental verification of the …


Investigation Of Luhn's Claim On Information Retrieval, İlker Kocabaş, Beki̇r Taner Di̇nçer, Bahar Karaoğlan Jan 2011

Investigation Of Luhn's Claim On Information Retrieval, İlker Kocabaş, Beki̇r Taner Di̇nçer, Bahar Karaoğlan

Turkish Journal of Electrical Engineering and Computer Sciences

In this study, we show how Luhn's claim about the degree of importance of a word in a document can be related to information retrieval. His basic idea is transformed into z-scores as the weights of terms for the purpose of modeling term frequency (tf) within documents. The Luhn-based models represented in this paper are considered as the TF component of proposed TF \times IDF weighing schemes. Moreover, the final term weighting functions appropriate for the TF \times IDF weighting scheme are applied to TREC-6, -7, and -8 databases. The experimental results show relevance to Luhn's claim by having high …


Line Detection With Adaptive Random Samples, Ali̇ Cafer Gürbüz Jan 2011

Line Detection With Adaptive Random Samples, Ali̇ Cafer Gürbüz

Turkish Journal of Electrical Engineering and Computer Sciences

This paper examines the detection of parameterized shapes in multidimensional noisy grayscale images. A novel shape detection algorithm utilizing random sample theory is presented. Although the method can be generalized, line detection is detailed. Each line in the image corresponds to a point in the line parameter space. The method creates hypothesis lines by randomly selecting parameter space points and tests the surrounding regions for acceptable linear features. The information obtained from each randomly selected line is used to update the parameter distribution, which reducesi the required number of random trials. The selected lines are re-estimated within a smaller search …


Design And Implementation Of A Voice-Controlled Prosthetic Hand, Musa Hakan Asyali, Mustafa Yilmaz, Mahmut Tokmakçi, Kanber Sedef, Beki̇r Hakan Aksebzeci̇, Rohin Mittal Jan 2011

Design And Implementation Of A Voice-Controlled Prosthetic Hand, Musa Hakan Asyali, Mustafa Yilmaz, Mahmut Tokmakçi, Kanber Sedef, Beki̇r Hakan Aksebzeci̇, Rohin Mittal

Turkish Journal of Electrical Engineering and Computer Sciences

Current hand prostheses are mostly driven by electromyography (EMG) signal, and existing experiments have proved that multichannel EMG signal controls are not suitable due to early fatigue problems and high effort requirements to perform even simple activities. Therefore, in this study we present a new voice-controlled active hand prosthesis to perform several basic tasks. We first designed a novel multifingered prosthetic hand with the ability of picking up and releasing objects. The prosthetic hand employs 3 DC motors and gears to transfer motion to the linked iparts of the fingers. We used flexible thin-film resistive force sensors at the fingertips …


Automatic Knowledge Extraction For Filling In Biography Forms From Turkish Texts, İlknur Pehli̇van, Zeynep Orhan Jan 2011

Automatic Knowledge Extraction For Filling In Biography Forms From Turkish Texts, İlknur Pehli̇van, Zeynep Orhan

Turkish Journal of Electrical Engineering and Computer Sciences

This study presents a method for building an automatic knowledge extraction system for filling in biography forms from Turkish texts. Several biographies are analyzed in order to choose the set of biography categories to be studied. The fields of the biography form to be created are also defined based on this analysis. Information extraction techniques are used for implementation. A separate testing platform is designed to evaluate the accuracy of the extracted data. Results of the testing platform have shown this study to be a promising process to be further developed especially for creating forms in the Turkish language.


Analysis Of Frequency Characteristics Of Electrical Arcs On The Insulating Sheath Of The Adss Fiber Optic Cables, Cengi̇z Polat Uzunoğlu, İbrahi̇m Güneş, Mukden Uğur Jan 2011

Analysis Of Frequency Characteristics Of Electrical Arcs On The Insulating Sheath Of The Adss Fiber Optic Cables, Cengi̇z Polat Uzunoğlu, İbrahi̇m Güneş, Mukden Uğur

Turkish Journal of Electrical Engineering and Computer Sciences

The insulating outer-sheath of ADSS (All dielectric self supporting) cables used on high voltage transmission lines are often subjected to various environmental effects. The ageing process of cable sheath can be investigated by using the dry-band arcing test method under laboratory conditions. Dry-band arcing is the most common technique to determine the ageing period of insulating materials. Environmental effects such as rain, humidity, dew and ice produce various amounts of wet regions on the cable surface. Electrical arcs and hence degradations are occurred on the cable surface due to the enhanced electrical field with formation of wet regions. In this …


Stray Magnetic Field Distributed Around A Pmsm, Ali̇ Ahmed Adam, Kayhan Gülez, Seli̇m Köroğlu Jan 2011

Stray Magnetic Field Distributed Around A Pmsm, Ali̇ Ahmed Adam, Kayhan Gülez, Seli̇m Köroğlu

Turkish Journal of Electrical Engineering and Computer Sciences

In this work, the low frequency electromagnetic emission from permanent magnet synchronous motors is studied. The main objective is to provide a safety region for humans in the vicinity of these motors, especially as these motors are now being used widely in inhabited areas, where high flux densities are expected. In this study, a new proposed equivalent magnetic circuit is used to estimate the stray fields at the surface of the motor. The analysis showed that the emission of the stray field in the radial direction depends on the permeability of the stator body. Low values of permeability may result …


Cooperative Diversity With Continuous Phase Modulation, Ni̇yazi̇ Odabaşioğlu Jan 2011

Cooperative Diversity With Continuous Phase Modulation, Ni̇yazi̇ Odabaşioğlu

Turkish Journal of Electrical Engineering and Computer Sciences

In recent years, there has been a vast amount of research on cooperative diversity due to its potential capacity increase. Almost all of the research has been based on linear modulation formats such as phase-shift keying (PSK) or quadrature amplitude modulation (QAM). On the other hand, continuous phase modulation (CPM) promises impressive advantages relative to linear modulations for wireless communication systems. In this paper, a cooperative diversity scheme with space-time coded (STC) CPM is introduced. Both amplify-and-forward (AF) and decode-and-forward (DF) modes were considered for cooperation. Simulation results showed that the proposed system is very suitable for wireless fading channels, …


A Novel And Efficient Algorithm For Adaptive Filtering: Artificial Bee Colony Algorithm, Nurhan Karaboğa, Mehmet Bahadir Çeti̇nkaya Jan 2011

A Novel And Efficient Algorithm For Adaptive Filtering: Artificial Bee Colony Algorithm, Nurhan Karaboğa, Mehmet Bahadir Çeti̇nkaya

Turkish Journal of Electrical Engineering and Computer Sciences

The uni-modal error surfaces and intrinsic stable behaviors of adaptive finite impulse response (FIR) filters make gradient based algorithms very effective in the design of these filters. Gradient based design methods are well developed for the design of adaptive FIR filters and widely applied to the distinct areas such as noise cancellation, system identification and channel equalization. However, the studies on adaptive infinite impulse response (IIR) filters are not as common as adaptive FIR filters since the stability during the adaptation process may not be ensured in some applications, and the convergence to the optimal design is not always guaranteed …


Determining Wave Propagation Characteristics Of Mv Xlpe Power Cable Using Time Domain Reflectometry Technique, Ghulam Murtaza Hashmi, Ruslan Papazyan, Matti Lehtonen Jan 2011

Determining Wave Propagation Characteristics Of Mv Xlpe Power Cable Using Time Domain Reflectometry Technique, Ghulam Murtaza Hashmi, Ruslan Papazyan, Matti Lehtonen

Turkish Journal of Electrical Engineering and Computer Sciences

In this paper, the wave propagation characteristics of single-phase medium voltage (MV) cross-linked polyethylene (XLPE) power cable are determined using time domain reflectometry (TDR) measurement technique. TDR delivers the complex propagation constant (attenuation and phase constant) of lossy cable transmission line as a function of frequency. The frequency-dependent propagation velocity is also determined from the TDR measurements through the parameters extraction procedure. The calibration of the measuring system (MS) is carried-out to avoid the effect of multiple reflections on the accuracy of measurements. The results obtained from the measurements can be used to localize the discontinuities as well as the …


New Srco With Explicit Current-Mode Output Using Two Ccs And Grounded Capacitors, D R. Bhaskar, Kasim K. Abdalla, Raj Senani Jan 2011

New Srco With Explicit Current-Mode Output Using Two Ccs And Grounded Capacitors, D R. Bhaskar, Kasim K. Abdalla, Raj Senani

Turkish Journal of Electrical Engineering and Computer Sciences

A new Grounded-Capacitor Single Resistance Controlled Sinusoidal Oscillator (SRCO) with explicit current output using two Current Conveyors (CCs) and five passive elements is presented. The proposed circuit offers (i) independent control of condition of oscillation and frequency of oscillation, (ii) low active and passive sensitivities, (iii) use of both the grounded capacitors (suitable for IC implementation) and (iv) reasonably good frequency stability. The workability of the proposed configuration has been confirmed by the PSPICE simulations.


Cognitive And Encrypted Communications: State Of The Art And A New Approach For Frequency-Agile Filters, Yahya Lakys, Balwant Godara, Alain Fabre Jan 2011

Cognitive And Encrypted Communications: State Of The Art And A New Approach For Frequency-Agile Filters, Yahya Lakys, Balwant Godara, Alain Fabre

Turkish Journal of Electrical Engineering and Computer Sciences

Several communication techniques are investigated in the first part of this paper: software radio, cognitive radio and encrypted communications. State of the art of research on agile and reconfigurable filters, passive as well as active, necessary for transceivers is then made and various tables for comparison are given. In the third part, a new theory for a 2^{nd}-order frequency-agile filter is introduced. The center frequency of the filter is proportional to the gain of a feedback amplifier and thus can be tuned over a wide frequency range. This new theory is thereafter generalized to the n^{th}-class leading to a center …


Asynchronous Signal Processing For Brain-Computer Interfaces, Seda Senay, Luis F. Chaparro, Mingui Sun, Robert Sclabassi, Aydin Akan Jan 2011

Asynchronous Signal Processing For Brain-Computer Interfaces, Seda Senay, Luis F. Chaparro, Mingui Sun, Robert Sclabassi, Aydin Akan

Turkish Journal of Electrical Engineering and Computer Sciences

Brain-computer interfaces (BCIs) provide a way to monitor and treat neurological diseases. An important application of BCIs is the monitoring and treatment of epilepsy, a neurological disorder characterized by recurrent unprovoked seizures, symptomatic of abnormal, excessive or synchronous neuronal activity in the brain. BCIs contain an array of sensors that gather and transmit data under the constrains of low-power and minimal data transmission. Asynchronous sigma delta modulators (ASDMs) are considered an alternative to synchronous analog to digital conversion. ASDMs are non-linear feedback systems that enable time-encoding of analog signals, from which the signal can be reconstructed. An efficient reconstruction of …


An Extended Component-Based Reliability Model For Protective Systems To Determine Routine Test Schedule, Amir Abbarin, Mahmoud Fotuhi Firuzabad, Aydoğan Özdemi̇r Jan 2011

An Extended Component-Based Reliability Model For Protective Systems To Determine Routine Test Schedule, Amir Abbarin, Mahmoud Fotuhi Firuzabad, Aydoğan Özdemi̇r

Turkish Journal of Electrical Engineering and Computer Sciences

This paper presents a novel approach for evaluating the reliability of protective systems taking into account its components reliability. In this paper, a previously proposed extended model is used for a directional over-current scheme. In the extended model, the impacts of individual protective components are taken into account. An optimum routine test schedule is determined for each protective component as a separate unit. A comparison is made to show that the proposed approach has excellence over conventional routine test inspections. Impacts of factors such as circuit breaker inadvertent opening, required time for performing routine test inspections, human mistakes and self-checking …


A Complete Motor Protection Algorithm Based On Pca And Ann: A Real Time Study, Okan Özgönenel, Turgay Yalçin Jan 2011

A Complete Motor Protection Algorithm Based On Pca And Ann: A Real Time Study, Okan Özgönenel, Turgay Yalçin

Turkish Journal of Electrical Engineering and Computer Sciences

Protection of an induction motor (IM) against possible faults, such as a stator winding fault, due to thermal deterioration, rotor bar and bearing failures, is very important in environments in which it is used intensively, as in industry as an actuator. In this work, a real time digital protection algorithm based on principal component analysis (PCA) and neural network method is presented for induction motors. The proposed protection algorithm covers internal winding faults (also known as stator faults), broken rotor bar faults, and bearing faults. Many laboratory experiments have been performed on a specially designed induction motor to evaluate the …


Online Speed Control Of A Brushless Ac Servomotor Based On Artificial Neural Networks, Si̇bel Partal, İbrahi̇m Şenol, Ahmet Faruk Bakan, Kamuran Nur Beki̇roğlu Jan 2011

Online Speed Control Of A Brushless Ac Servomotor Based On Artificial Neural Networks, Si̇bel Partal, İbrahi̇m Şenol, Ahmet Faruk Bakan, Kamuran Nur Beki̇roğlu

Turkish Journal of Electrical Engineering and Computer Sciences

In this paper, an alternative approach to speed estimation of brushless AC servomotors is presented. Speed control is realized in the following steps. First, the servomotor was mathematically modelled; the driver system was designed and speed control of the servomotor was accomplished with feedback. Next, a network structure representing the electrical and mechanical properties of the servomotor was built via Artificial Neural Network (ANN) and trained with the results of the first step. The weights obtained from the neural nwork training were inserted into the control algorithm in accordance with the ANN. Finally, speed estimation was achieved based on the …


Obtaining The Secondary Impedance Of Single-Sided Linear Induction Motor With A Double Layer Reaction Rail: A New Approach, Ali̇ Suat Gerçek, Vedat Mehmet Karsli Jan 2011

Obtaining The Secondary Impedance Of Single-Sided Linear Induction Motor With A Double Layer Reaction Rail: A New Approach, Ali̇ Suat Gerçek, Vedat Mehmet Karsli

Turkish Journal of Electrical Engineering and Computer Sciences

In the performance calculations of single-sided linear induction motor (SLIM),the equivalent circuit technique (ECT) is used. In this paper, a new approach is proposed for obtaining the secondary impedance of single-sided linear induction motor (SLIM) with a double layer reaction rail by using the layered secondary model. The proposed method improves the ECT technique by considering the saturation effect and the non-linear complex equivalent relative permeability. This study also examines the contributions of other electromagnetic effects, such as longitudinal end effect and transverse edge effect as well. Our method is applied to the SLIM and computed results of the method …


Rate 1 Space-Time And Space-Frequency Spreading Diversity Technique, Gökçe Hacioğlu, Ali̇ Gangal Jan 2011

Rate 1 Space-Time And Space-Frequency Spreading Diversity Technique, Gökçe Hacioğlu, Ali̇ Gangal

Turkish Journal of Electrical Engineering and Computer Sciences

In this study, a rate 1 transmitter diversity technique is proposed. The proposed technique uses spreading transform and space-time block coding (STBC) together. Space-time, space-frequency, and frequency diversity applications of the proposed technique are shown. The code matrix of the proposed technique can be designed systematically. The proposed technique needs the channel coefficients to stay constant over transmission of 2 rows of the coding matrix regardless of the size of the coding matrix or the diversity order. However, joint detection of the symbols is required for the proposed technique. We used computer simulations to compare our technique with the quasi-orthogonal …


On The Existence Of Common Lyapunov Functions For Consensus Algorithms Based On Averaging, Mehmet Akar, Robert Shorten Jan 2011

On The Existence Of Common Lyapunov Functions For Consensus Algorithms Based On Averaging, Mehmet Akar, Robert Shorten

Turkish Journal of Electrical Engineering and Computer Sciences

This paper addresses distributed deterministic consensus algorithms based on averaging. We relate the conditions for achieving consensus to the existence of a common norm for a set of row-stochastic matrices associated with the original set of averaging matrices. For a system to achieve consensus, it is shown that this associated set of matrices should have a Common Lyapunov Function, even if the original set might not have one.


Ecg Denoising On Bivariate Shrinkage Function Exploiting Interscale Dependency Of Wavelet Coefficients, Sema Kayhan, Ergun Erçelebi̇ Jan 2011

Ecg Denoising On Bivariate Shrinkage Function Exploiting Interscale Dependency Of Wavelet Coefficients, Sema Kayhan, Ergun Erçelebi̇

Turkish Journal of Electrical Engineering and Computer Sciences

This paper presents a new method for electrocardiogram (ECG) denoising based on bivariate shrinkage functions exploiting the interscale dependency of wavelet coefficients. Most nonlinear thresholding methods based on wavelet transform denoising assume that the wavelet coefficients are independent. However, wavelet coefficients of ECG signals have significant dependencies. In this paper, we proposed a new method by considering the dependencies between the coefficients and their parents in detail on a bivariate shrinkage function for denoising of an ECG signal corrupted by different types of noises, such as muscle artifact noise, electrode motion, and white noise. In real-time applications, reduction of computational …


Sliding Mode Controller Gain Adaptation And Chattering Reduction Techniques For Dsp-Based Pm Dc Motor Drives, Mehmet Dal, Remus Teodorescu Jan 2011

Sliding Mode Controller Gain Adaptation And Chattering Reduction Techniques For Dsp-Based Pm Dc Motor Drives, Mehmet Dal, Remus Teodorescu

Turkish Journal of Electrical Engineering and Computer Sciences

In order to achieve and maintain the prospective benefits of sliding mode control (SMC) methodology, the phenomenon known as ``chattering'', the main obstacle encountered in real-time applications, has to be suppressed. In this study, two promising switching control gain adaptation and chattering reduction techniques are investigated, and the effectiveness of chattering suppression for current regulation of PM DC drives is tested. The sampling rate was also examined to determine how it affects the amplitude of chattering. This paper concentrates on various combinations of observer-based methods in order to find the best solution for chattering reduction. To find a practical solution …


Minimization Of Load Shedding By Sequential Use Of Linear Programming And Particle Swarm Optimization, Mehrdad Tarafdar Hagh, Sadjad Galvani Jan 2011

Minimization Of Load Shedding By Sequential Use Of Linear Programming And Particle Swarm Optimization, Mehrdad Tarafdar Hagh, Sadjad Galvani

Turkish Journal of Electrical Engineering and Computer Sciences

Minimization of load shedding during contingency conditions is solved as an optimization problem. As a new topic, instead of local load shedding, total load shedding of a large power system is considered. Power generation rescheduling is considered to minimize the load shedding, as well. Different importance factors for buses are also considered. The linear programming method (LP) is used to solve this problem in a short period of time without considering some power system constraints. Particle swarm optimization (PSO) is also used to solve the problem by considering all power system constraints, but with a longer solving time. Finally, a …


Design Of Cdba-Based Active Polyphase Filter For Low-If Receiver Applications, Mehmet Sağbaş Jan 2011

Design Of Cdba-Based Active Polyphase Filter For Low-If Receiver Applications, Mehmet Sağbaş

Turkish Journal of Electrical Engineering and Computer Sciences

A novel first-order active-RC polyphase filter section, using current differencing buffered amplifiers (CDBAs), is presented. The section uses 6 resistors, 2 capacitors, and 2 CDBAs. The transfer function of the proposed section has a single pole and optionally a single zero. Increasing the number of cascading sections, any higher order polyphase filter can be realized. This paper also introduces the leakage caused by element deviation and the effects of the amplifier in nonideal cases. Furthermore, nonideal performances of the proposed filter section are tested with PSpice simulations.