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2016

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Articles 9421 - 9450 of 9593

Full-Text Articles in Engineering

Comprehensive Review Of Association Estimators For The Inference Of Gene Networks, Zeyneb Kurt Yavuz, Ni̇zametti̇n Aydin, Gökmen Altay Jan 2016

Comprehensive Review Of Association Estimators For The Inference Of Gene Networks, Zeyneb Kurt Yavuz, Ni̇zametti̇n Aydin, Gökmen Altay

Turkish Journal of Electrical Engineering and Computer Sciences

Gene network inference (GNI) algorithms allow us to explore the vast amount of interactions among the molecules in cells. In almost all GNI algorithms the main process is to estimate association scores among the variables of the dataset. However, there is no commonly accepted estimator to compute association scores for the current GNI algorithms. In this paper the association estimators that might be used in GNI applications are reviewed. The aim is to prepare a comprehensive and comparative review of all the important association estimators available in the literature. We performed this main aim by presenting, classifying, comparing, and discussing …

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Design Of A High-Linear, High-Precision Analog Multiplier, Free From Body Effect, Ali Naderi Saatlo, İsmai̇l Serdar Özoğuz Jan 2016

Design Of A High-Linear, High-Precision Analog Multiplier, Free From Body Effect, Ali Naderi Saatlo, İsmai̇l Serdar Özoğuz

Turkish Journal of Electrical Engineering and Computer Sciences

In this paper, a new CMOS four-quadrant analog multiplier circuit is proposed, based on a pair of dual-translinear loops. The significant features of the circuit are its high accuracy and high linearity as well as its body effect-free operation, owing to the fact that the circuit relies on a new dual-translinear topology. In addition, harmonic distortions are precisely discussed due to their conceivable mismatches, including transconductance and threshold voltage of the transistors. HSPICE postlayout simulation results are presented to verify the validity of the theoretical analysis, where under a supply voltage of 2.8 V, the bandwidth of the proposed multiplier …

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Feature Selection For Movie Recommendation, Zehra Çataltepe, Mahi̇ye Uluyağmur, Esengül Tayfur Jan 2016

Feature Selection For Movie Recommendation, Zehra Çataltepe, Mahi̇ye Uluyağmur, Esengül Tayfur

Turkish Journal of Electrical Engineering and Computer Sciences

TV users have an abundance of different movies they could choose from, and with the quantity and quality of data available both on user behavior and content, better recommenders are possible. In this paper, we evaluate and combine different content-based and collaborative recommendation methods for a Turkish movie recommendation system. Our recommendation methods can make use of user behavior, different types of content features, and other users' behavior to predict movie ratings. We gather different types of data on movies, such as the description, actors, directors, year, and genre. We use natural language processing methods to convert the Turkish movie …

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A Mapreduce-Based Distributed Svm Algorithm For Binary Classification, Ferhat Özgür Çatak, Mehmet Erdal Balaban Jan 2016

A Mapreduce-Based Distributed Svm Algorithm For Binary Classification, Ferhat Özgür Çatak, Mehmet Erdal Balaban

Turkish Journal of Electrical Engineering and Computer Sciences

Although the support vector machine (SVM) algorithm has a high generalization property for classifying unseen examples after the training phase~and a small loss value, the algorithm is not suitable for real-life classification and regression problems. SVMs cannot solve hundreds of thousands of examples in a training dataset. In previous studies on distributed machine-learning algorithms, the SVM was trained in a costly and preconfigured computer environment. In this research, we present a MapReduce-based distributed parallel SVM training algorithm for binary classification problems. This work shows how to distribute optimization problems over cloud computing systems with the MapReduce technique. In the second …

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Discriminant-Based Bistability Analysis Of A Tmg-Induced Lac Operon Model Supported With Boundedness And Local Stability Results, Nesli̇han Avcu, Güleser Kalayci Demi̇r, Ferhan Pekergi̇n, Hakan Alyürük, Levent Çavaş, Cüneyt Güzeli̇ş Jan 2016

Discriminant-Based Bistability Analysis Of A Tmg-Induced Lac Operon Model Supported With Boundedness And Local Stability Results, Nesli̇han Avcu, Güleser Kalayci Demi̇r, Ferhan Pekergi̇n, Hakan Alyürük, Levent Çavaş, Cüneyt Güzeli̇ş

Turkish Journal of Electrical Engineering and Computer Sciences

This paper presents the results of a theoretical and numerical study on the analysis of bistable behavior of the most studied gene regulatory network, the lac operon, in terms of the model parameters. The boundedness of the state variables for the considered model are demonstrated, the parameter values providing the existence of the multiple equilibria and thus the bistable behavior are determined, and a local stability analysis of the equilibria is performed. The parameter region yielding the existence of multiple equilibria is determined in an algebraic way based on discriminants. The model given in the state equation form is defined …

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Sizing Design And Implementation Of A Flywheel Energy Storage System For Space Applications, Kutlay Aydin, Mehmet Ti̇mur Aydemi̇r Jan 2016

Sizing Design And Implementation Of A Flywheel Energy Storage System For Space Applications, Kutlay Aydin, Mehmet Ti̇mur Aydemi̇r

Turkish Journal of Electrical Engineering and Computer Sciences

Flywheel energy storage systems have become an important research subject in recent years. They are also considered for space applications instead of hazardous and bulky electrochemical batteries. In this paper, a flywheel energy storage system has been designed for satellite attitude control systems. Power requirements of a small commercial satellite have been used as the starting point of the design. The designed system includes a BLDC motor. The machine is run as a motor for 60 min and the stored energy is discharged during the following 30 min to simulate low orbit satellite operation. Experimental results show that these systems …

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Walsh Series Modeling And Estimation In Sensorless Position Control Of Electrical Drives, Hamidreza Shirazi, Jalal Nazarzadeh Jan 2016

Walsh Series Modeling And Estimation In Sensorless Position Control Of Electrical Drives, Hamidreza Shirazi, Jalal Nazarzadeh

Turkish Journal of Electrical Engineering and Computer Sciences

High-performance electrical drives can be achieved by using field-oriented controllers, which make torque and flux naturally decoupled. A conventional vector-controlled drive has the disadvantage of either requiring flux and speed sensors or being affected by rotor resistance, which varies along with the motor performance. The presented paper focuses on developing a high-performance sensorless rotor flux-oriented controller of an induction machine independent of the rotor resistance variation. This method applies spectral theory of Walsh functions, which are one of the most helpful members of piecewise constant basis functions in solving dynamic models. Inherent characteristics of Walsh functions and application of an …

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Quantitative Information Extraction From Gas Sensor Data Using Principal Component Regression, Ahmet Özmen, Beki̇r Mumyakmaz, Mehmet Ali̇ Ebeoğlu, Ci̇hat Taşaltin, İlke Gürol, Zafer Zi̇ya Öztürk, Deni̇z Dural Jan 2016

Quantitative Information Extraction From Gas Sensor Data Using Principal Component Regression, Ahmet Özmen, Beki̇r Mumyakmaz, Mehmet Ali̇ Ebeoğlu, Ci̇hat Taşaltin, İlke Gürol, Zafer Zi̇ya Öztürk, Deni̇z Dural

Turkish Journal of Electrical Engineering and Computer Sciences

This paper presents a novel use of the principal component analysis (PCA) and regression methods for quantitative feature extraction from gas sensor data. In this approach, PCA plots are interpreted by observing the locations of samples in the principal component domain. A trainable data processing system that also produces numerical output is designed to validate the method. The main advantages of this system are: 1) retrainability: once it is trained, it can be used for any gas set; 2) flexibility: adaptation to different targets does not require hardware modifications (if a sufficient number and variety of sensors are installed in …

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A Parametric Study On Privatization Revenues Of The Electricity Distribution Companies In Turkey, Ercan İzgi̇, Seli̇m Ay Jan 2016

A Parametric Study On Privatization Revenues Of The Electricity Distribution Companies In Turkey, Ercan İzgi̇, Seli̇m Ay

Turkish Journal of Electrical Engineering and Computer Sciences

The privatization of electricity distribution companies in the state monopoly has increased significantly in recent years. Privatization is expected to improve the quality of services in the electric distribution sector and to provide additional income to the state. In this paper the privatization revenues of the 18 electricity distribution companies in Turkey are calculated through regression equations. The privatization revenues of the electricity distribution companies are identified by 5 models containing microeconomic and macroeconomic variables (parameters). The study indicates a correlation between the considered variables and the privatization revenues of the electricity distribution companies and useful parametric formulations are proposed. …

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A Novel Key Distribution Scheme Against Storage-Bounded Adversaries Using Attack Probabilities, Mohammad Farhadi Bajestani, Ali Payandeh Jan 2016

A Novel Key Distribution Scheme Against Storage-Bounded Adversaries Using Attack Probabilities, Mohammad Farhadi Bajestani, Ali Payandeh

Turkish Journal of Electrical Engineering and Computer Sciences

Key establishment proves to be a challenging problem in wireless sensor networks. A key establishment scheme needs to incorporate properties like scalability and energy efficiency. We propose a scheme that, besides enjoying a desirable scalability, consumes resources according to attack probability within each region. In this scheme, the distribution area is divided into regions of varying attack probability. It is assumed that the adversary is storage bounded and that not all communications can be stored by the adversary. This scheme is highly resistant to node compromises and there is an extremely low probability of discovering the key by the adversary …

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Speciation-Based Genetic Algorithm In Analog Circuit Design, Hasari̇ Karci̇, Gülay Tohumoğlu, Ari̇f Nacaroğlu Jan 2016

Speciation-Based Genetic Algorithm In Analog Circuit Design, Hasari̇ Karci̇, Gülay Tohumoğlu, Ari̇f Nacaroğlu

Turkish Journal of Electrical Engineering and Computer Sciences

This paper presents a speciation procedure that improves the local search capability of the genetic algorithm in analog circuit design. There is no need for additional circuit simulation in order to apply this procedure. The procedure is tested in Gaussian, sigmoid, cube, and square circuit design problems. Two sets of 125 simulations with the same seed values are performed for each problem using both the proposed procedure and the canonical genetic algorithm. The simulation results show that the method is statistically better than the canonical genetic algorithm, which suffers from bad locality. The effects of the population size and speciation …

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Square Root Central Difference-Based Fastslam Approach Improved By Differential Evolution, Haydar Ankişhan, Fi̇kret Ari, Emre Öner Tartan, Ahmet Güngör Pakfi̇li̇z Jan 2016

Square Root Central Difference-Based Fastslam Approach Improved By Differential Evolution, Haydar Ankişhan, Fi̇kret Ari, Emre Öner Tartan, Ahmet Güngör Pakfi̇li̇z

Turkish Journal of Electrical Engineering and Computer Sciences

This study presents a new approach to improve the performance of FastSLAM. The aim of the study is to obtain a more robust algorithm for FastSLAM applications by using a Kalman filter that uses Stirling's polynomial interpolation formula. In this paper, some new improvements have been proposed; the first approach is the square root central difference Kalman filter-based FastSLAM, called SRCD-FastSLAM. In this method, autonomous vehicle (or robot) position, landmarks' position estimations, and importance weight calculations of the particle filter are provided by the SRCD-Kalman filter. The second approach is an improved version of the SRCD-FastSLAM in which particles are …

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Optimization With Genetic Algorithm Of Temperature-Dependent Fiber Length Of L-Band Edfa Gain, Murat Yücel, Damt Adnan Mustafa Mustafa Jan 2016

Optimization With Genetic Algorithm Of Temperature-Dependent Fiber Length Of L-Band Edfa Gain, Murat Yücel, Damt Adnan Mustafa Mustafa

Turkish Journal of Electrical Engineering and Computer Sciences

Erbium-doped fiber amplifiers (EDFAs) have great importance in long-distance communication. It is required to have equal gain for all signals that are transferred and to avoid loss in the receiver of long-distance communication systems. However, temperature dependence changes the output spectrum of the designed gain-flattening systems. In this study, each erbium-doped fiber (EDF) length of a two-stage L-band EDFA has been optimized using a genetic algorithm method; because of the temperature dependence of EDFAs, there is no general rule. Thus, a simple, fast, dynamic, and highly accurate model has been developed and obtained for different EDF lengths that will fix …

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Development Of Radiometer Operating Between 50 Mhz And 26.5 Ghz Using Gain-Stabilized Lna, Murat Celep, Şenel Yaran, Cem Hayirli, Ari̇f Dolma Jan 2016

Development Of Radiometer Operating Between 50 Mhz And 26.5 Ghz Using Gain-Stabilized Lna, Murat Celep, Şenel Yaran, Cem Hayirli, Ari̇f Dolma

Turkish Journal of Electrical Engineering and Computer Sciences

A radiometer operating between 50 MHz and 26.5 GHz and consisting of microwave channels all with a low-noise amplifier (LNA) was established. Microwave switches were used to select an appropriate channel according to measurement frequency. The effect of variations both in input and output reflection coefficients on LNA gain was investigated. To keep the change in the gain of the LNA at minimum, the LNA output was terminated with a load whose impedance was equal to that of matched load. This technique gives the opportunity of full-band noise measurements of noise sources with one total power radiometer. The performance of …

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An Advanced Optimization Technique For Considering Reliability Issues And Unit Commitment Problems Simultaneously, Ahmad Heidari, Mohammad Reza Alizadeh Pahlavani, Hamid Dehghani Jan 2016

An Advanced Optimization Technique For Considering Reliability Issues And Unit Commitment Problems Simultaneously, Ahmad Heidari, Mohammad Reza Alizadeh Pahlavani, Hamid Dehghani

Turkish Journal of Electrical Engineering and Computer Sciences

This paper presents an advanced optimization technique to solve unit commitment problems and reliability issues simultaneously for thermal generating units. To solve unit commitment, generalized Benders decomposition along with a genetic algorithm are proposed to include minimum up/down time constraints, and for reliability issues consideration, a fuzzy stochastic-based technique is presented. To implement the problem into an optimization program, MATLAB software and CPLEX and KNITRO solvers are applied. To verify the proposed technique and algorithm, two case studies, the IEEE 14- and 118-bus systems, are implemented for optimal generation scheduling and reliability issues. Finally, a comparison with other solution techniques …

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Variations And Relations Of Meteorological Parameters Between Upwind And Downwind Small-Scale Wind Turbine Rotor Area, Ercan İzgi̇, Mustafa Kemal Kaymak, Ahmet Öztopal, Bi̇hter Durna, Ahmet Duran Şahi̇n Jan 2016

Variations And Relations Of Meteorological Parameters Between Upwind And Downwind Small-Scale Wind Turbine Rotor Area, Ercan İzgi̇, Mustafa Kemal Kaymak, Ahmet Öztopal, Bi̇hter Durna, Ahmet Duran Şahi̇n

Turkish Journal of Electrical Engineering and Computer Sciences

Renewable energy sources are becoming increasingly important due to climate change and the energy crisis. Wind energy projects and applications in particular have been growing recently. Meteorological parameters such as wind speed, ambient temperature, relative humidity, and air pressure directly affect wind turbine electricity generation. Understanding the relationships among these parameters is necessary to determine wind energy potential and to predict electricity generation. The current work is based on data obtained from a 1.5 kW wind turbine constructed in İstanbul Technical University's meteorological park in Turkey. A one minute time interval was used in the data analysis. In this study, …

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Artificial Bee Colony Algorithm Based Optimal Reactive Power Flow Of Two-Terminal Hvdc Systems, Ulaş Kiliç, Kürşat Ayan Jan 2016

Artificial Bee Colony Algorithm Based Optimal Reactive Power Flow Of Two-Terminal Hvdc Systems, Ulaş Kiliç, Kürşat Ayan

Turkish Journal of Electrical Engineering and Computer Sciences

This paper presents a solution technique for the optimal reactive power flow (ORPF) of alternating current-direct current (AC-DC) power systems using the artificial bee colony (ABC) algorithm. A high voltage direct current (HVDC) transmission link is one of the most important network components in AC-DC power systems. In recent years there has been an increasing number of studies related to power systems with HVDC transmission links. One of them is the reactive power flow (RPF) optimization. The aim of ORPF in alternating current (AC) or AC-DC power systems is to minimize transmission line power loss under equality and inequality constraints. …

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A Classification Of Semantic Conflicts In Heterogeneous Web Services At Message Level, Ibrahim Ahmed Al Baltah, Abdul Azim Abdul Ghani, Wan Nurhayati Wan Ab Rahman, Rodziah Atan Jan 2016

A Classification Of Semantic Conflicts In Heterogeneous Web Services At Message Level, Ibrahim Ahmed Al Baltah, Abdul Azim Abdul Ghani, Wan Nurhayati Wan Ab Rahman, Rodziah Atan

Turkish Journal of Electrical Engineering and Computer Sciences

Since the last decade, semantic conflicts have been considered as a critical problem in establishing seamless message exchange between Web services. To provide the essential step for solving this problem, semantic conflicts have to be defined and classified properly. Most of the existing classifications that attempt to classify semantic conflicts lack completeness and accuracy. Therefore, this paper aims at proposing a new complete and accurate semantic conflicts classification, whose purposes are identifying and classifying all potential conflicts that may arise in heterogeneous Web services at the message level. This classification has three main classes based on the cause of conflicts, …

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An Application Of Simulated Annealing To Optimal Transcranial Direct Current Stimulation Of The Human Brain, Raheleh Tavakoli, Hamed Sadjedi, Seyyed Mohammad Pourmir Firoozabadi Jan 2016

An Application Of Simulated Annealing To Optimal Transcranial Direct Current Stimulation Of The Human Brain, Raheleh Tavakoli, Hamed Sadjedi, Seyyed Mohammad Pourmir Firoozabadi

Turkish Journal of Electrical Engineering and Computer Sciences

Transcranial direct current stimulation (tDCS) is known as the most effective technique for stimulating deeper brain areas. The capability of tDCS, however, strongly depends on the number of electrodes, their positions, and the amount of injected currents. This paper intends to apply the simulated annealing algorithm for determining optimal stimulation parameters in a multiple electrode scheme. The objective of the presented approach is to maximize the current density delivered to the target area under safety constraints. In order for the skin under the electrodes to be protected against temperature rises that may be caused by the stimulation, current injections are …

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An Unsupervised Heterogeneous Log-Based Framework For Anomaly Detection, Asif Iqbal Hajamydeen, Nur Izura Udzir, Ramlan Mahmod, Abdul Azim Abdul Ghani Jan 2016

An Unsupervised Heterogeneous Log-Based Framework For Anomaly Detection, Asif Iqbal Hajamydeen, Nur Izura Udzir, Ramlan Mahmod, Abdul Azim Abdul Ghani

Turkish Journal of Electrical Engineering and Computer Sciences

Log analysis is a method to identify intrusions at the host or network level by scrutinizing the log events recorded by the operating systems, applications, and devices. Most work contemplates a single type of log for analysis, leading to an unclear picture of the situation and difficulty in deciding the existence of an intrusion. Moreover, most existing detection methods are knowledge-dependent, i.e. using either the characteristics of an anomaly or the baseline of normal traffic behavior, which limits the detection process to only anomalies based on the acquired knowledge. To discover a wide range of anomalies by scrutinizing various logs, …

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On Scalable Rdfs Reasoning Using A Hybrid Approach, Tuğba Külahcioğlu, Hasan Bulut Jan 2016

On Scalable Rdfs Reasoning Using A Hybrid Approach, Tuğba Külahcioğlu, Hasan Bulut

Turkish Journal of Electrical Engineering and Computer Sciences

Reasoning is a vital ability for semantic web applications since they aim to understand and interpret the data on the World Wide Web. However, reasoning of large data sets is one of the challenges facing semantic web applications. In this paper, we present new approaches for scalable Resource Description Framework Schema (RDFS) reasoning. Our RDFS specific term-based partitioning algorithm determines required schema elements for each data partition while eliminating the data partitions that will not produce any inferences. With the two-level partitioning approach, we are able to carry out reasoning with limited resources. In our hybrid approach, we integrate two …

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Ray Tracing Technique For Shaping A Dual Reflector Antenna System, Md Rezwanul Ahsan, Mohammad Tariqul Islam, Yoshihide Yamada, Norbahiah Misran Jan 2016

Ray Tracing Technique For Shaping A Dual Reflector Antenna System, Md Rezwanul Ahsan, Mohammad Tariqul Islam, Yoshihide Yamada, Norbahiah Misran

Turkish Journal of Electrical Engineering and Computer Sciences

In radio astronomy applications, antennas having the highest aperture efficiencies are requested. In order to meet this request, a reflector shaping program for dual reflector antennas has been developed. The design procedure is based on the geometrical optics where differential equations have been formulated to define the ray trace of the antenna system. Recently, the fourth generation programming language MATLAB has become well known for its numerical computing environment and very useful three-dimensional data visualization functions. The authors wished to make a dual reflector shaping program by a ray tracing method in MATLAB. In this paper, details of the program …

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An Enhanced Multiinterface Multichannel Algorithm For High Quality Live Video Streaming Over Hybrid Wmns, Behrang Barekatain, Mohd Aizaini Maarof, Alfonso Ariza Quintana, Alicia Triviño-Cabrera, Hamid Reza Ghaeini Jan 2016

An Enhanced Multiinterface Multichannel Algorithm For High Quality Live Video Streaming Over Hybrid Wmns, Behrang Barekatain, Mohd Aizaini Maarof, Alfonso Ariza Quintana, Alicia Triviño-Cabrera, Hamid Reza Ghaeini

Turkish Journal of Electrical Engineering and Computer Sciences

Recently, providing live video streaming over hybrid wireless mesh networks (WMNs) has been of great interest. In this kind of network, most of the users usually move with low speed and always keep their connections within the network by attaching to different mesh routers (MRs). When evaluating a mesh technology, it is important to pay special attention to this kind of device as it is mostly handled by the final user. These devices, known as STA nodes, neither run a routing protocol nor perform forwarding operations. Although our proposed distributed locator service in GREENIE makes hybrid WMNs more efficient for …

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Gender Classification: A Convolutional Neural Network Approach, Shan Sung Liew, Mohamed Khalil Hani, Syafeeza Ahmad Radzi, Rabia Bakhteri Jan 2016

Gender Classification: A Convolutional Neural Network Approach, Shan Sung Liew, Mohamed Khalil Hani, Syafeeza Ahmad Radzi, Rabia Bakhteri

Turkish Journal of Electrical Engineering and Computer Sciences

An approach using a convolutional neural network (CNN) is proposed for real-time gender classification based on facial images. The proposed CNN architecture exhibits a much reduced design complexity when compared with other CNN solutions applied in pattern recognition. The number of processing layers in the CNN is reduced to only four by fusing the convolutional and subsampling layers. Unlike in conventional CNNs, we replace the convolution operation with cross-correlation, hence reducing the computational load. The network is trained using a second-order backpropagation learning algorithm with annealed global learning rates. Performance evaluation of the proposed CNN solution is conducted on two …

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Modeling And Control Of A Doubly Fed Induction Generator With A Disturbance Observer: A Stator Voltage Oriented Approach, Eşref Emre Özsoy, Edin Golubovic, Asif Sabanovic, Seta Bogosyan, Meti̇n Gökaşan Jan 2016

Modeling And Control Of A Doubly Fed Induction Generator With A Disturbance Observer: A Stator Voltage Oriented Approach, Eşref Emre Özsoy, Edin Golubovic, Asif Sabanovic, Seta Bogosyan, Meti̇n Gökaşan

Turkish Journal of Electrical Engineering and Computer Sciences

The popularity of renewable energy conversion systems, and especially of wind energy, has been growing in recent years. Doubly fed induction generator (DFIG)-based wind energy systems are extensively used due to their wide range of active and reactive power controllability. Conventional DFIG control structures consist of decoupled PI rotor current controllers with stator flux orientation and machine parameter-dependent compensating terms. The accuracy of stator flux calculations is dependent on how accurately the stator resistance is known. Integration problems also exist and additional low-pass filters are implemented to accurately calculate the stator flux. In the current study, machine-dependent compensating terms are …

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A Novel Approach Of Design And Analysis Of Fractal Antenna Using A Neurocomputational Method For Reconfigurable Rf Mems Antenna, Paras Chawla, Rajesh Khanna Jan 2016

A Novel Approach Of Design And Analysis Of Fractal Antenna Using A Neurocomputational Method For Reconfigurable Rf Mems Antenna, Paras Chawla, Rajesh Khanna

Turkish Journal of Electrical Engineering and Computer Sciences

A mathematical neural approach/artificial neural network (ANN) for the design of a swastika-shaped reconfigurable antenna as a feedforward side is proposed. Further design parameter calculations using the reverse procedure of the above method is presented. Neural network computational is one of the optimization methods that could be considered to improve the performance of the device. In this paper, the proposed planar antenna up to the 2nd iteration is simulated using finite element method-based HFSS software. The developed ANN algorithm method allows the optimization of the antenna to be carried out by exchanging repetitive simulations and also provides reduced processing times …

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Power Regulated Dc/Dc Driver Design By Hierarchical Control, Bariş Baykant Alagöz, Cemal Keleş, Asi̇m Kaygusuz, Yusuf Kaplan, Abdul Keri̇m Karabi̇ber Jan 2016

Power Regulated Dc/Dc Driver Design By Hierarchical Control, Bariş Baykant Alagöz, Cemal Keleş, Asi̇m Kaygusuz, Yusuf Kaplan, Abdul Keri̇m Karabi̇ber

Turkish Journal of Electrical Engineering and Computer Sciences

As a result of advances in solid-state power electronics, DC power distribution has found widespread usage due to its advantages. DC/DC converters, which are mainly used for voltage regulation, are fundamental components of DC power distribution systems. This paper presents a peak power controlled DC/DC converter design based on a two-layer hierarchical closed-loop control strategy for active DC power management. The proposed DC/DC converter design, called a power regulated DC/DC driver, limits output power according to current-voltage characteristic of a modified sigmoid function and it allows more secure and controllable power delivery in DC distribution buses. As a design example, …

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Grid-Connected Induction Generator Interturn Fault Analysis Using A Pca-Ann-Based Algorithm, Haydar Bayar, Ümi̇t Kemaletti̇n Terzi̇ Jan 2016

Grid-Connected Induction Generator Interturn Fault Analysis Using A Pca-Ann-Based Algorithm, Haydar Bayar, Ümi̇t Kemaletti̇n Terzi̇

Turkish Journal of Electrical Engineering and Computer Sciences

It is difficult for short circuits among the internal windings of one phase in electrical machines to be determined in a reliable and speedy manner. The failure currents that occur, especially in short circuits with a few windings, are at such low levels that they cannot be determined by relay systems. This results in growing faults and damage. In this study, we designed a model that can define winding failures successfully at very small levels by using the PCA and ANN algorithms. We tested the real-time faults and measured the system performance with the installed test rig. The developed protection …

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Source Detection And Propagation Of Equal Frequency Voltage Flicker In Nonradial Power System, Abdolmajid Dejamkhooy, Ali Dastfan, Alireza Ahmadyfard Jan 2016

Source Detection And Propagation Of Equal Frequency Voltage Flicker In Nonradial Power System, Abdolmajid Dejamkhooy, Ali Dastfan, Alireza Ahmadyfard

Turkish Journal of Electrical Engineering and Computer Sciences

Nowadays electric power quality problems such as flicker (voltage fluctuation) are major concerns of electric companies and industrial consumers. Identification of flicker sources is an important stage in the flicker reduction process. Flicker source can be modeled as a nonlinear load whose admittance is intermittent and time-variant. In the steady state, fluctuation of voltage amplitude is a function of the impedance of flicker sources. In this paper, after calculating the gradient of voltage amplitudes and constructing a Jacobian matrix, criteria for flicker source detection are proposed. Therefore, by measuring voltage and current of each load in the power system, the …

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Reconstructive Sensing Circuit For Complementary Resistive Switches-Based Crossbar Memories, Ertuğrul Karakulak, Reşat Mutlu, Erdem Uçar Jan 2016

Reconstructive Sensing Circuit For Complementary Resistive Switches-Based Crossbar Memories, Ertuğrul Karakulak, Reşat Mutlu, Erdem Uçar

Turkish Journal of Electrical Engineering and Computer Sciences

Complementary resistive switches (CRSs) are suggested as an alternative to one-cell memristor memories to decrease leakage currents. However, their sensing is more difficult and complex than one-cell memristor memories. A method has been given for sensing their state using only DC voltages in the literature. However, in this strategy, sensing one of the logic states results in the destruction of the state and the destroyed state must be written again. To the best of our knowledge, a circuit with this sensing strategy does not exist in the literature yet. In this paper, such a circuit employing this method, which is …

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