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2011

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Articles 1651 - 1680 of 1795

Full-Text Articles in Computer Sciences

Learning Control Of Robot Manipulators In The Presence Of Additive Disturbances, Enver Tatlicioğlu Jan 2011

Learning Control Of Robot Manipulators In The Presence Of Additive Disturbances, Enver Tatlicioğlu

Turkish Journal of Electrical Engineering and Computer Sciences

In this paper, a learning controller for robot manipulators is developed. The controller is proven to yield in a semi-global asymptotic result in the presence of additive input and output disturbances. Lyapunov-based techniques are used to guarantee that the tracking error is asymptotically driven to zero. Numerical simulation results are presented to demonstrate the viability of the proposed learning controller.

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A Multi-Lateral Rehabilitation System, Aykut Ci̇han Satici, Ahmetcan Erdoğan, Volkan Patoğlu Jan 2011

A Multi-Lateral Rehabilitation System, Aykut Ci̇han Satici, Ahmetcan Erdoğan, Volkan Patoğlu

Turkish Journal of Electrical Engineering and Computer Sciences

This paper proposes a multi-lateral shared control concept for robot assisted rehabilitation. In particular, a dual-user force-feedback teleoperation control architecture is implemented on a forearm-wrist rehabilitation system consisting of two kinematically dissimilar robotic devices. The multi-lateral rehabilitation system allows for patients to train with on-line virtual dynamic tasks in collaboration with a therapist. Different control authority can be assigned to each agent so that therapists can guide or evaluate movements of patients, or share the control with them. The collaboration is implemented using a dual-user force-feedback teleoperation control architecture, in which a dominance factor determines the authority of each agent …

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Design And Control Of The Humanoid Robot Suralp, Kemaletti̇n Erbatur, Utku Seven, Evri̇m Taşkiran, Özer Koca, Meti̇n Yilmaz, Mustafa Ünel, Güllü Kiziltaş Şendur, Asif Sabanovic, Ahmet Onat Jan 2011

Design And Control Of The Humanoid Robot Suralp, Kemaletti̇n Erbatur, Utku Seven, Evri̇m Taşkiran, Özer Koca, Meti̇n Yilmaz, Mustafa Ünel, Güllü Kiziltaş Şendur, Asif Sabanovic, Ahmet Onat

Turkish Journal of Electrical Engineering and Computer Sciences

SURALP is a 29 degrees-of-freedom full-body walking humanoid robot designed and constructed at Sabanci University - Turkey. The human-sized robot is actuated by DC motors, belt and pulley systems and Harmonic Drive reduction gears. The sensory equipment consists of joint encoders, force/torque sensors, inertial measurement systems and cameras. The control hardware is based on a dSpace digital signal processor. This paper reviews the design of this robot and presents experimental walking results. A posture zeroing procedure is followed after manual zeroing of the robot joints. Controllers for landing impact reduction, early landing trajectory modification, foot-ground orientation compliance, body inclination and …

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Ellipsoid Based L_2 Controller Design For Lpv Systems With Saturating Actuators, İbrahi̇m Beklan Küçükdemi̇ral, Levent Ucun, Yavuz Eren, Haluk Görgün, Gali̇p Cansever Jan 2011

Ellipsoid Based L_2 Controller Design For Lpv Systems With Saturating Actuators, İbrahi̇m Beklan Küçükdemi̇ral, Levent Ucun, Yavuz Eren, Haluk Görgün, Gali̇p Cansever

Turkish Journal of Electrical Engineering and Computer Sciences

This paper addresses the L_2 gain control problem for disturbance attenuation in Linear Parameter Varying (LPV) Systems having saturating actuators when the system is subjected to L_2 disturbances. In the presented method, saturating actuator is expressed analytically with a convex hull of some linear feedback which let us construct L_2 control problem via Linear Matrix Inequalities (LMIs) which are obtained by some ellipsoids. It is shown that the stability and disturbance rejection capabilities of the control system are all measured by means of these nested ellipsoids where the inner ellipsoid covers the initial conditions for states whereas the outer ellipsoid …

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Spoiler Effects Reduction With Using Active Power Filter On A Direct Torque Controlled Induction Machine, İbrahi̇m Alişkan, Kayhan Gülez, Yusuf Altun Jan 2011

Spoiler Effects Reduction With Using Active Power Filter On A Direct Torque Controlled Induction Machine, İbrahi̇m Alişkan, Kayhan Gülez, Yusuf Altun

Turkish Journal of Electrical Engineering and Computer Sciences

Harmonics, which may be placed in electrical systems, have important effects on performance parameters of electrical motors. In this paper, effects of electrical power system voltage harmonics on torque position of induction motors are dealt with. System modeling with Pulse Width Modulation (PWM) type Active Power Filter (APF) is used for reducing these effects. APF, as a subsystem, is placed into torque control system entrance to save the control system and induction motor output torque. Motor outputs, that are before-after APF connections, are handed for understanding effects of voltage harmonics. Since APF design was based on voltage harmonics, Electromagnetic Interference …

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Semi-Active H_{\Infty} Robust Control Of Six Degree Of Freedom Structural System Using Mr Damper, Şaban Çeti̇n, Seli̇m Si̇vri̇oğlu, Erkan Zergeroğlu, İsmai̇l Yüksek Jan 2011

Semi-Active H_{\Infty} Robust Control Of Six Degree Of Freedom Structural System Using Mr Damper, Şaban Çeti̇n, Seli̇m Si̇vri̇oğlu, Erkan Zergeroğlu, İsmai̇l Yüksek

Turkish Journal of Electrical Engineering and Computer Sciences

In this study, H_{\infty} robust control is designed for vibration attenuation of six DOF structure using MR damper. A semi-active seismically excited, nonlinear structural system is modelled. The controller is designed for a reduced order model and applied to the full order model. The controller performance is verified experimentally. It is shown that the H_{\infty} controller performance is satisfactory to suppress the vibration of the structure despite the presence of uncertainties.

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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 …

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Model Predictive Controller Design Of Hydrocracker Reactors, Di̇la Gökçe Jan 2011

Model Predictive Controller Design Of Hydrocracker Reactors, Di̇la Gökçe

Turkish Journal of Electrical Engineering and Computer Sciences

This study summarizes the design of a Model Predictive Controller (MPC) in Tüpraş, İzmit Refinery Hydrocracker Unit Reactors. Hydrocracking process, in which heavy vacuum gasoil is converted into lighter and valuable products at high temperature and pressure is described briefly. Controller design description, identification and modeling studies are examined and the model variables are presented. WABT (Weighted Average Bed Temperature) equalization and conversion increase are simulated, results are discussed.

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Design And Development Of A Tilt-Wing Uav, Ertuğrul Çeti̇nsoy, Efe Sirimoğlu, Kaan Taha Öner, Cevdet Hançer, Mustafa Ünel, Mahmut Faruk Akşi̇t, İlyas Kandemi̇r, Kayhan Gülez Jan 2011

Design And Development Of A Tilt-Wing Uav, Ertuğrul Çeti̇nsoy, Efe Sirimoğlu, Kaan Taha Öner, Cevdet Hançer, Mustafa Ünel, Mahmut Faruk Akşi̇t, İlyas Kandemi̇r, Kayhan Gülez

Turkish Journal of Electrical Engineering and Computer Sciences

In this paper, the mechanical and aerodynamic design, carbon composite production, hierarchical control system design and vertical flight tests of a new unmanned aerial vehicle (UAV), which is capable of VTOL (vertical takeoff and landing) like a helicopter and long range horizontal flight like an airplane, are presented. Real flight tests show that the aerial vehicle can successfully operate in VTOL mode. Kalman filtering is employed to obtain accurate roll and pitch angle estimations.

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Linear Motor For Multi--Car Elevators: Design And Position Measurement, Çağri Gürbüz, Ender Kazan, Ahmet Onat, Sandor Markon Jan 2011

Linear Motor For Multi--Car Elevators: Design And Position Measurement, Çağri Gürbüz, Ender Kazan, Ahmet Onat, Sandor Markon

Turkish Journal of Electrical Engineering and Computer Sciences

Multi-car elevator is an emerging technology consisting of two or more elevator cars moving independently in an elevator hoistway, which has become more appealing as building heights increase. In this paper, the design and drive methodologies for a linear motor driven multi-car elevator system with independently moving cars is introduced together with experimental results. Additionally, a safety method developed for the linear motor elevator and the conditions necessary for its proper operation are discussed. The new results introduced in this paper are in the areas of the design method of the linear motor for multi-car elevator system, and the preliminary …

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Active Vibration Control Of Seismic Excited Structural System Using Lmi-Based Mixed H_2/H_{\Infty} State Feedback Controller, Hakan Yazici, Rahmi̇ Güçlü Jan 2011

Active Vibration Control Of Seismic Excited Structural System Using Lmi-Based Mixed H_2/H_{\Infty} State Feedback Controller, Hakan Yazici, Rahmi̇ Güçlü

Turkish Journal of Electrical Engineering and Computer Sciences

This paper is concerned with the active vibration control of a four-degree-of-freedom structure, which is effected by earthquake. To obtain desired time history and frequency responses for solution of active vibration control problem, Linear Matrix Inequality (LMI) based state-feedback mixed H_2/H_{\infty} controller is designed in this study. The time history of ground motion of the Kobe earthquake in 1995, which is a disturbance input, is applied to modeled structure. At the end of the study, the time history of the storey displacements, velocities and frequency responses of both controlled and uncontrolled cases are presented and results are discussed. Performance of …

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Delay Compensation In Bilateral Control Using A Sliding Mode Observer, Tuğba Leblebi̇ci̇, Berk Çalli, Mustafa Ünel, Asif Sabanovic, Seta Bogosyan, Meti̇n Gökaşan Jan 2011

Delay Compensation In Bilateral Control Using A Sliding Mode Observer, Tuğba Leblebi̇ci̇, Berk Çalli, Mustafa Ünel, Asif Sabanovic, Seta Bogosyan, Meti̇n Gökaşan

Turkish Journal of Electrical Engineering and Computer Sciences

In bilateral control applications, time delays in the communication channel have destabilizing effects and cause degradations in the performance of the system. In this paper, a sliding mode observer is used in conjunction with a disturbance observer to predict states of the slave system. Predicted states are then used in control formulation. Simulation and experimental results show that the proposed method avoids instability due to time delays in bilateral operation and provides satisfactory performance.

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Induction Motor, State Estimation, Extended Kalman Filtering, Recurrent Neural Networks, Saadetti̇n Aksoy, Aydin Mühürcü Jan 2011

Induction Motor, State Estimation, Extended Kalman Filtering, Recurrent Neural Networks, Saadetti̇n Aksoy, Aydin Mühürcü

Turkish Journal of Electrical Engineering and Computer Sciences

This study presents a recurrent neural network (RNN)-based nonlinear state estimator that uses an Elman neural network structure (ENN) for state estimation of a squirrel-cage induction motor. The proposed algorithm only uses the measurements of the stator currents and the rotor angular speed, and it learns the dynamic behavior of the state observer from these measurements through prediction error minimization. A squirrel-cage induction motor was fed from sinusoidal, 6-step, and pulse-width modulation (PWM) supply sources at different times in order to observe the performance of the proposed estimator for different operation conditions. Estimation results showed that the proposed algorithm is …

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Application Of A Hybrid Evolutionary Technique For Efficiency Determination Of A Submersible Induction Motor, Mümtaz Mutluer, Osman Bi̇lgi̇n Jan 2011

Application Of A Hybrid Evolutionary Technique For Efficiency Determination Of A Submersible Induction Motor, Mümtaz Mutluer, Osman Bi̇lgi̇n

Turkish Journal of Electrical Engineering and Computer Sciences

Electric motors are the largest consumers of electricity in plants and induction motors constitute nearly two-thirds of them. The replacement of in-service induction motors with more efficient ones is a very important strategy for energy savings and consequently nearly 30 different methods have been used to determine the efficiency of induction motors in the last 2 decades. This paper aims to develop the efficiency determination of a 20 Hp submersible induction motor. Due to getting perfect efficiency of the submersible induction motor, a robust hybrid evolutionary optimization technique, which consists of a genetic algorithm and simulated annealing, is used. The …

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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 …

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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 …

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Using Learning Automata For Multi-Objective Generation Dispatch Considering Cost, Voltage Stability And Power Losses, Ari̇f Karakaş, Celal Kocatepe, Fangxing Li Jan 2011

Using Learning Automata For Multi-Objective Generation Dispatch Considering Cost, Voltage Stability And Power Losses, Ari̇f Karakaş, Celal Kocatepe, Fangxing Li

Turkish Journal of Electrical Engineering and Computer Sciences

The economical and secure operation of power systems has significant importance. Due to technical limitations, the best economical operation point is not always the desired operating point for system stability or power losses. In this study, first, the most economical operating point is obtained by solving the non-linear, network-constrained economic dispatch problem using a genetic algorithm. Then, the system voltage stability is analyzed to compare the different possible operating points using V-Q sensitivity analysis. The power losses, obtained for various operating points, are considered the third objective function. Finally, these 3 aspects of cost, voltage stability, and power losses are …

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An Algorithm To Minimize Within-Class Scatter And To Reduce Common Matrix Dimension For Image Recognition, Ümi̇t Çi̇ğdem Turhal, Alpaslan Duysak Jan 2011

An Algorithm To Minimize Within-Class Scatter And To Reduce Common Matrix Dimension For Image Recognition, Ümi̇t Çi̇ğdem Turhal, Alpaslan Duysak

Turkish Journal of Electrical Engineering and Computer Sciences

In this paper, a new algorithm using 2DPCA and Gram-Schmidt Orthogonalization Procedure for recognition of face images is proposed. The algorithm consists of two parts. In the first part, a common feature matrix is obtained; and in the second part, the dimension of the common feature matrix is reduced. Resulting common feature matrix with reduced dimension is used for face recognition. Column and row covariance matrices are obtained by applying 2DPCA on the column and row vectors of images, respectively. The algorithm then applies eigenvalue-eigenvector decomposition to each of these two covariance matrices. Total scatter maximization is achieved taking the …

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Change Detection Without Difference Image Computation Based On Multiobjective Cost Function Optimization, Turgay Çeli̇k, Zeki̇ Yetgi̇n Jan 2011

Change Detection Without Difference Image Computation Based On Multiobjective Cost Function Optimization, Turgay Çeli̇k, Zeki̇ Yetgi̇n

Turkish Journal of Electrical Engineering and Computer Sciences

In this paper, we propose a novel method for unsupervised change detection in multi-temporal satellite images by using multiobjective cost function optimization via genetic algorithm (GA). The spatial image grid of the input multi-temporal satellite images is divided into two distinct regions, representing ``changed'' and ``unchanged'' regions between input images, via the intermediate change detection mask produced by the GA. The dissimilarity of pixels of ``changed'' regions and similarity of pixels of ``unchanged'' regions between input multi-temporal images are measured using image quality metrics which consider correlation, spectral distortion, radiometric distortion, and contrast distortion. The contextual information of each pixel …

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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 …

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Statistical Significance Based Graph Cut Regularization For Medical Image Segmentation, Sema Candemi̇r, Yusuf Si̇nan Akgül Jan 2011

Statistical Significance Based Graph Cut Regularization For Medical Image Segmentation, Sema Candemi̇r, Yusuf Si̇nan Akgül

Turkish Journal of Electrical Engineering and Computer Sciences

Graph cut minimization formulates the image segmentation as a linear combination of problem constraints. The salient constraints of the computer vision problems are data and smoothness which are combined through a regularization parameter. The main task of the regularization parameter is to determine the weight of the smoothness constraint on the graph energy. However, the difference in functional forms of the constraints forces the regularization weight to balance the inharmonious relationship between the constraints. This paper proposes a new idea: bringing the data and smoothness terms on the common base decreases the difference between the constraint functions. Therefore the regularization …

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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 …

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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 …

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Design And Evaluation Of A Query-Based Jamming Detection Algorithm For Wireless Sensor Networks, Murat Çakiroğlu, Ahmet Turan Özceri̇t Jan 2011

Design And Evaluation Of A Query-Based Jamming Detection Algorithm For Wireless Sensor Networks, Murat Çakiroğlu, Ahmet Turan Özceri̇t

Turkish Journal of Electrical Engineering and Computer Sciences

Jamming attacks, which are the main cause of data corruption and network blockages in wireless sensor networks (WSNs), are one of the most serious threats for WSNs. This type of attack not only blocks the ongoing communication in the network, but also causes the wireless nodes to exhaust their energy much earlier than expected. A countermeasure must be deployed against jamming attacks, especially in military and medical applications in which security breaches cannot be tolerated. In this paper, we have designed a new query-based jamming detection algorithm (QUJDA) to detect jamming attacks occurring in WSNs. QUJDA is an attack detection …

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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 …

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Co-Occurrence Matrix And Its Statistical Features As A New Approach For Face Recognition, Alaa Eleyan, Hasan Demirel Jan 2011

Co-Occurrence Matrix And Its Statistical Features As A New Approach For Face Recognition, Alaa Eleyan, Hasan Demirel

Turkish Journal of Electrical Engineering and Computer Sciences

In this paper, a new face recognition technique is introduced based on the gray-level co-occurrence matrix (GLCM). GLCM represents the distributions of the intensities and the information about relative positions of neighboring pixels of an image. We proposed two methods to extract feature vectors using GLCM for face classification. The first method extracts the well-known Haralick features from the GLCM, and the second method directly uses GLCM by converting the matrix into a vector that can be used in the classification process. The results demonstrate that the second method, which uses GLCM directly, is superior to the first method that …

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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 …

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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 …

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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, …

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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 …

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