Open Access. Powered by Scholars. Published by Universities.®

Physical Sciences and Mathematics Commons™

Open Access. Powered by Scholars. Published by Universities.®

Computer Engineering

TÜBİTAK

Journal

2015

Articles 151 - 166 of 166

Full-Text Articles in Physical Sciences and Mathematics

Epilepsy Diagnosis Using Artificial Neural Network Learned By Pso, Nesi̇be Yalçin, Gülay Tezel, Ci̇han Karakuzu Jan 2015

Epilepsy Diagnosis Using Artificial Neural Network Learned By Pso, Nesi̇be Yalçin, Gülay Tezel, Ci̇han Karakuzu

Turkish Journal of Electrical Engineering and Computer Sciences

Electroencephalogram (EEG) is used routinely for diagnosis of diseases occurring in the brain. It is a very useful clinical tool in the classification of epileptic seizures and the diagnosis of epilepsy. In this study, epilepsy diagnosis has been investigated using EEG records. For this purpose, an artificial neural network (ANN), widely used and known as an active classification technique, is applied. The particle swarm optimization (PSO) method, which does not need gradient calculation, derivative information, or any solution of differential equations, is preferred as the training algorithm for the ANN. A PSO-based neural network (PSONN) model is diversified according to …

Go to article

An Ofdm Throughput Analysis For Cognitive Radio Application In Contiguous Or Noncontiguous Tv White Spaces, Cebrai̇l Çi̇fli̇kli̇, Ahmet Turgut Tuncer, Yusuf Öztürk Jan 2015

An Ofdm Throughput Analysis For Cognitive Radio Application In Contiguous Or Noncontiguous Tv White Spaces, Cebrai̇l Çi̇fli̇kli̇, Ahmet Turgut Tuncer, Yusuf Öztürk

Turkish Journal of Electrical Engineering and Computer Sciences

Radio frequency spectrum is a finite and scarce resource. Efficient use of the radio frequency spectrum is a fundamental research issue. Since a large portion of the assigned radio frequency spectrum is used only sporadically, the bands currently allocated to TV services can be opportunistically reassigned to support broadband networking services while continuing to provide broadcast TV. The fragmented and unused TV channels named white spaces have a considerable amount of bandwidth potential and long transmission ranges. Bandwidth scalability can be supported by bonding multiple contiguous or noncontiguous consecutive channels using orthogonal frequency division multiplexing (OFDM)-based cognitive radio. In this …

Go to article

A Hierarchic Approach Based On Swarm Intelligence To Solve The Traveling Salesman Problem, Mesut Gündüz, Mustafa Servet Kiran, Eren Özceylan Jan 2015

A Hierarchic Approach Based On Swarm Intelligence To Solve The Traveling Salesman Problem, Mesut Gündüz, Mustafa Servet Kiran, Eren Özceylan

Turkish Journal of Electrical Engineering and Computer Sciences

The purpose of this paper is to present a new hierarchic method based on swarm intelligence algorithms for solving the well-known traveling salesman problem. The swarm intelligence algorithms implemented in this study are divided into 2 types: path construction-based and path improvement-based methods. The path construction-based method (ant colony optimization (ACO)) produces good solutions but takes more time to achieve a good solution, while the path improvement-based technique (artificial bee colony (ABC)) quickly produces results but does not achieve a good solution in a reasonable time. Therefore, a new hierarchic method, which consists of both ACO and ABC, is proposed …

Go to article

Mras-Based Sensorless Speed Backstepping Control For Induction Machine, Using A Flux Sliding Mode Observer, Mohamed Moutchou, Ahmed Abbou, Hassan Mahmoudi Jan 2015

Mras-Based Sensorless Speed Backstepping Control For Induction Machine, Using A Flux Sliding Mode Observer, Mohamed Moutchou, Ahmed Abbou, Hassan Mahmoudi

Turkish Journal of Electrical Engineering and Computer Sciences

In this paper, an induction machine rotor speed and rotor flux control using a sensorless backstepping control scheme is discussed. The most interesting point of this technique is that it deals with the nonlinearity of a high-order system by using the virtual control variable to make this system simple, and thus the control outputs can be derived step by step through appropriate Lyapunov functions. To avoid the use of a mechanical sensor, the rotor speed estimation is made by an observer using the model reference adaptive system (MRAS) technique; in order to estimate rotor flux, a sliding mode observer is …

Go to article

Synthesis Of Real-Time Cloud Applications For Internet Of Things, Slawomir Bak, Radoslaw Czarnecki, Stanislaw Deniziak Jan 2015

Synthesis Of Real-Time Cloud Applications For Internet Of Things, Slawomir Bak, Radoslaw Czarnecki, Stanislaw Deniziak

Turkish Journal of Electrical Engineering and Computer Sciences

This paper presents the methodology for the synthesis of real-time applications working in the ``Internet of Things'' environment. We propose the client-server architecture, where embedded systems act as smart clients and the Internet application is a server of the system. The architecture of the application conforms to the cloud computing model. Since centralized systems are prone to bottlenecks caused by accumulation of transmissions or computations, we propose the distributed architecture of the server and the methodology that constructs this architecture using Internet resources supported by a cloud provider. We assume that the function of the server is specified as a …

Go to article

A Performance Comparison Of Conventional And Transverse Flux Linear Switched Reluctance Motors, Nuretti̇n Üstkoyuncu, Krishnan Ramu Jan 2015

A Performance Comparison Of Conventional And Transverse Flux Linear Switched Reluctance Motors, Nuretti̇n Üstkoyuncu, Krishnan Ramu

Turkish Journal of Electrical Engineering and Computer Sciences

This paper presents a comprehensive comparison between conventional (longitudinal flux) linear switched reluctance machines (CLSRMs) and transverse flux linear switched reluctance machines (TLSRMs) so as to enable engineers to choose a structure suitable for their applications. A commonly-used single-sided CLSRM and 4 different TLSRM structures are considered for the comparison. For a fair comparison of the 2 types of LSRMs, equal dimensions, including equal length and magnetomotive force, are applied as much as possible. The analytical approach and 3-dimensional finite element analysis (FEA) are employed to obtain the performance of these machines. It is proven analytically that the CLSRM has …

Go to article

Automatic Classification Of Harmonic Data Using $K$-Means And Least Square Support Vector Machine, Hüseyi̇n Eri̇şti̇, Vedat Tümen, Özal Yildirim, Belkis Eri̇şti̇, Yakup Demi̇r Jan 2015

Automatic Classification Of Harmonic Data Using $K$-Means And Least Square Support Vector Machine, Hüseyi̇n Eri̇şti̇, Vedat Tümen, Özal Yildirim, Belkis Eri̇şti̇, Yakup Demi̇r

Turkish Journal of Electrical Engineering and Computer Sciences

In this paper, an effective classification approach to classify harmonic data has been proposed. In the proposed classifier approach, harmonic data obtained through a 3-phase system have been classified by using $k$-means and least square support vector machine (LS-SVM) models. In order to obtain class details regarding harmonic data, a $k$-means clustering algorithm has been applied to these data first. The training of the LS-SVM model has been realized with the class details obtained through the $k$-means algorithm. To increase the efficiency of the LS-SVM model, the regularization and kernel parameters of this model have been determined with a grid …

Go to article

Intelligent Text Classification System Based On Self-Administered Ontology, Manoj Manuja, Deepak Garg Jan 2015

Intelligent Text Classification System Based On Self-Administered Ontology, Manoj Manuja, Deepak Garg

Turkish Journal of Electrical Engineering and Computer Sciences

Over the last couple of decades, web classification has gradually transitioned from a syntax- to semantic-centered approach that classifies the text based on domain ontologies. These ontologies are either built manually or populated automatically using machine learning techniques. A prerequisite condition to build such systems is the availability of ontology, which may be either full-fledged domain ontology or a seed ontology that can be enriched automatically. This is a dependency condition for any given semantics-based text classification system. We share the details of a proof of concept of a web classification system that is self-governed in terms of ontology population …

Go to article

Low-Cost Sliding Mode Control Of Wecs Based On Dfig With Stability Analysis, Abdelhak Djoudi, Hachemi Chekireb, El Madjid Berkouk, Seddik Bacha Jan 2015

Low-Cost Sliding Mode Control Of Wecs Based On Dfig With Stability Analysis, Abdelhak Djoudi, Hachemi Chekireb, El Madjid Berkouk, Seddik Bacha

Turkish Journal of Electrical Engineering and Computer Sciences

The aim of this work is to developing sliding mode control of active and reactive stator powers produced by a wind energy conversion system (WECS), based on doubly fed induction generator (DFIG). A flux estimation model and rotor current sensor are no longer required. The controller is developed from the DFIG nonlinear-coupled model. Moreover, the global stability and the DFIG states' boundedness when our low-cost sliding mode control is applied are established analytically. It is revealed that the $(dq)$ components of the rotor flux remain near their nominal values. Our approach is validated via simulation in the case of a …

Go to article

The Integrated Control Of Fuzzy Logic And Model-Based Approach For Variable-Speed Wind Turbine, Jian Yang, Dongran Song, Hua Han, Pengsha Tong, Ling Zhou Jan 2015

The Integrated Control Of Fuzzy Logic And Model-Based Approach For Variable-Speed Wind Turbine, Jian Yang, Dongran Song, Hua Han, Pengsha Tong, Ling Zhou

Turkish Journal of Electrical Engineering and Computer Sciences

For a variable-speed wind turbine (VSWT), the primary objective of control is to maximize power generation while maintaining the desired rotor speed and avoiding equipment overloads. To fulfill the control objectives, the classical model-based control (MBC) has been widely used, which refers to two controllers: torque controller (TC) and pitch controller (PC). In this work, the drawbacks of MBC for VSWTs are studied extensively. It reveals that there are transition issues between the TC and PC, and over-speed problems under large turbulent wind when only MBC is taken. To improve the control performance of the VSWT, an integrated control solution …

Go to article

Model-Reference Sliding Mode Control Of A Three-Phase Four-Leg Voltage Source Inverter For Stand-Alone Distributed Generation Systems, Ayhan Özdemi̇r, İrfan Yazici, Zeki̇ye Erdem Jan 2015

Model-Reference Sliding Mode Control Of A Three-Phase Four-Leg Voltage Source Inverter For Stand-Alone Distributed Generation Systems, Ayhan Özdemi̇r, İrfan Yazici, Zeki̇ye Erdem

Turkish Journal of Electrical Engineering and Computer Sciences

This paper proposes a discrete-time model-reference sliding mode control of three-phase four-leg voltage source inverters for stand-alone distributed generation systems. Three-phase four-leg voltage source inverters (VSIs) are used in a broad area. A discrete-time model-reference sliding mode controller, having superior advantages such as insensitivity to external disturbances, system parameter variations, and modeling errors, is applied to control the output voltage of three-phase four-leg VSIs. As a new study, the discrete-time model-reference sliding mode control with a supplemented output feedback integral controller is proposed so that the controlled output voltages of the VSI tracks the input reference signal. The controller is …

Go to article

Transient Stability Analysis Of Vsc Hvdc Transmission With Power Injection On The Dc-Link, Agha Francis Nnachi, Josiah Munda, Dan Valentine Nicolae, Augustin Mabwe Mpanda Jan 2015

Transient Stability Analysis Of Vsc Hvdc Transmission With Power Injection On The Dc-Link, Agha Francis Nnachi, Josiah Munda, Dan Valentine Nicolae, Augustin Mabwe Mpanda

Turkish Journal of Electrical Engineering and Computer Sciences

The utilization of a DC-link transmission corridor of embedded VSC HVDC for a DC power injection from renewable energy sources to increase the power flow capability and AC network stability support is a promising technology. However, DC faults on the DC transmission line are likely to threaten the system's operation and stability, especially when the DC power injection exceeds certain limits. A DC single line-to-earth fault is the most likely fault scenario and its effect on the VSC HVDC operation will depend on the earth-loop impedance. Adding an injection point on the DC-link will reduce the earth-loop impedance, hence imposing …

Go to article

Renewable Energy Integration In Smart Grids-Multicriteria Assessment Using The Fuzzy Analytical Hierarchy Process, Aleksandar Janjic, Suzana Savic, Lazar Velimirovic, Vesna Nikolic Jan 2015

Renewable Energy Integration In Smart Grids-Multicriteria Assessment Using The Fuzzy Analytical Hierarchy Process, Aleksandar Janjic, Suzana Savic, Lazar Velimirovic, Vesna Nikolic

Turkish Journal of Electrical Engineering and Computer Sciences

Unlike the traditional way of efficiency assessment of renewable energy sources integration, the smart grid concept is introducing new goals and objectives regarding increased use of renewable electricity sources, grid security, energy conservation, energy efficiency, and deregulated energy market. Possible benefits brought by renewable sources integration are evaluated by the degree of the approach to the ideal smart grid. In this paper, fuzzy analytical hierarchy process methodology for the integration efficiency has been proposed, taking into account the presence of multiple criteria of both qualitative and quantitative nature, different performance indicators, and the uncertain environment of the smart grid. The …

Go to article

Speech Emotion Recognition Using Nonlinear Dynamics Features, Ali Shahzadi, Alireza Ahmadyfard, Ali Harimi, Khashayar Yaghmaie Jan 2015

Speech Emotion Recognition Using Nonlinear Dynamics Features, Ali Shahzadi, Alireza Ahmadyfard, Ali Harimi, Khashayar Yaghmaie

Turkish Journal of Electrical Engineering and Computer Sciences

Recent developments in man--machine interaction have motivated researchers to recognize human emotion from speech signals. In this study, we propose using nonlinear dynamics features (NLDs) for emotion recognition. NLDs are extracted from the geometrical properties of the reconstructed phase space of speech signals. The traditional prosodic and spectral features are also used as a benchmark. The Fisher discriminant ratio acts as a filter to remove irrelevant features quickly. Then a wrapper method based on a genetic algorithm and support vector machine is employed to find the best feature subset that obtains the maximum recognition rate. The classification accuracy of the …

Go to article

A Comparative Study Of Two Different Fpga-Based Arrhythmia Classifier Architectures, Ahmet Turan Özdemi̇r, Kenan Danişman Jan 2015

A Comparative Study Of Two Different Fpga-Based Arrhythmia Classifier Architectures, Ahmet Turan Özdemi̇r, Kenan Danişman

Turkish Journal of Electrical Engineering and Computer Sciences

Early diagnosis of dangerous heart conditions is very important for the treatment of heart diseases and for the prevention of sudden cardiac death. Automatic electrocardiogram (ECG) arrhythmia classifiers are essential to timely diagnosis. However, most of the medical diagnosis systems proposed in the literature are software-based. This work focused on the hardware implementation of a mobile artificial neural network (ANN)-based arrhythmia classifier that is implemented on a field programmable gate array (FPGA) as a single chip solution, as an alternative to various software models of ANNs. Due to the parallel nature of ANNs, hardware implementation of ANNs needs a large …

Go to article

Analysis And Design Of An Interleaved Current-Fed High Step-Up Quasi-Resonant Dc-Dc Converter For Fuel Cell Applications, Sina Salehi, Behrooz Vahidi, Jafar Milimonfared, Maghdad Taheri, Hadi Moradi Jan 2015

Analysis And Design Of An Interleaved Current-Fed High Step-Up Quasi-Resonant Dc-Dc Converter For Fuel Cell Applications, Sina Salehi, Behrooz Vahidi, Jafar Milimonfared, Maghdad Taheri, Hadi Moradi

Turkish Journal of Electrical Engineering and Computer Sciences

This paper proposes a current-fed quasi-resonant converter with soft switching method. Input current ripple is reduced by employing two boost circuits at the input, which makes this converter appropriate for fuel cell application. Current stress on switches is reduced because of the resonance in switches, and also, as a result of zero voltage switching in switches, switching losses will be reduced in this proposed converter. In the output, the reverse recovery problem of diodes is alleviated by zero current switching, so there is no need for fast diodes anymore. The reduction of losses improves the efficiency, and in a wide …

Go to article

First Prev