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Articles 136711 - 136740 of 304096

Full-Text Articles in Physical Sciences and Mathematics

A Second-Order Volterra Filter-Based Nonlinear Clipping Detector, Jihwan Park, Joon-Hyuk Chang Jan 2016

A Second-Order Volterra Filter-Based Nonlinear Clipping Detector, Jihwan Park, Joon-Hyuk Chang

Turkish Journal of Electrical Engineering and Computer Sciences

In this paper, we propose a novel nonlinear clipping detector based on the second-order Volterra filter for an acoustic echo canceller (AEC). Since the performance of the conventional AEC algorithm drastically deteriorates when nonlinear clipping occurs, the adaptive filter pauses adaptation during the nonlinear clipping periods to avoid unwanted divergence. These nonlinear clipping periods are detected in our method using the magnitude spectrum of the quadratic Volterra filter in lower frequency ranges. Through extensive computer-based simulation results considering an acoustic room environment and various clipping levels, it is found that the proposed approach is effective in detecting the nonlinear clipping …

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Solar Irradiation Estimator Based On A Self-Calibrated Reference Solar Cell, Touria Hassboun, Lhoussain El Bahir, Youness Aite Driss, Mustapha El Adnani Jan 2016

Solar Irradiation Estimator Based On A Self-Calibrated Reference Solar Cell, Touria Hassboun, Lhoussain El Bahir, Youness Aite Driss, Mustapha El Adnani

Turkish Journal of Electrical Engineering and Computer Sciences

In this paper we propose a concept for estimating solar irradiation based on measurements of the current, voltage, and temperature of a photovoltaic (PV) cell. The estimation of the irradiation is obtained by processing these measurements using a PV cell mathematical model combined with a PI controller. Since the PV cell current is very sensitive to the irradiance level, the principle of the method is to force the model to reproduce the same current as that measured on the cell by applying an appropriate irradiance as input, for measured temperature and voltage. The appropriate irradiance, which is the output of …

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Applying Metaheuristic Optimization Methods To Design Novel Adaptive Pi-Type Fuzzy Logic Controllers For Load-Frequency Control In A Large-Scale Power Grid, Thimaiphuong Dao, Yaonan Wang, Ngockhoat Nguyen Jan 2016

Applying Metaheuristic Optimization Methods To Design Novel Adaptive Pi-Type Fuzzy Logic Controllers For Load-Frequency Control In A Large-Scale Power Grid, Thimaiphuong Dao, Yaonan Wang, Ngockhoat Nguyen

Turkish Journal of Electrical Engineering and Computer Sciences

Due to the complexity and diversity of large-scale power systems in practice, designing load-frequency control (LFC) strategies against load variations faces big challenges to ensure the stability and economy of the network. The focus of this paper is to design a novel adaptive PI-type fuzzy logic (FL)-based LFC architecture for solving the LFC problem in such an interconnected electric power grid. Applying 2 biologically inspired optimization methods, namely particle swarm optimization method and a genetic algorithm, the membership functions and rule base of a basic PI-type FL model were parameterized and optimized simultaneously and successfully. An online self-tuning method was …

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Balancing Exploration And Exploitation By Using Sequential Execution Cooperation Between Artificial Bee Colony And Migrating Birds Optimization Algorithms, Hasan Makas, Nejat Yumuşak Jan 2016

Balancing Exploration And Exploitation By Using Sequential Execution Cooperation Between Artificial Bee Colony And Migrating Birds Optimization Algorithms, Hasan Makas, Nejat Yumuşak

Turkish Journal of Electrical Engineering and Computer Sciences

The artificial bee colony (ABC) algorithm is a metaheuristic search method inspired by bees' foraging behaviour. With its global search ability in scout bee phase, it can easily escape from local optimum traps in the problem space. Therefore, it is good at exploration. The migrating birds optimization (MBO) algorithm is another recent metaheuristic search method. It simulates birds' V flight formation, which minimizes energy consumption during flight. The MBO algorithm achieves a good convergence to the global optimum by using its own unique benefit mechanism. That is, it has a good exploitation capability. This paper aimed to combine the good …

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Minimum Number Of Permanent-Magnet Synchronous Generators For Coordinated Low-Voltage Ride-Through Of Induction Generators In Hybrid Wind Farms, Shenghu Li, Rui An Jan 2016

Minimum Number Of Permanent-Magnet Synchronous Generators For Coordinated Low-Voltage Ride-Through Of Induction Generators In Hybrid Wind Farms, Shenghu Li, Rui An

Turkish Journal of Electrical Engineering and Computer Sciences

Coordinated low-voltage ride-through (LVRT) of induction generators (IGs) utilizing the excessive reactive power of permanent magnet synchronous generators (PMSGs) in hybrid wind farms is attractive due to saving investments on shunt compensators. The existing research is mainly based on dynamic simulations to given scenarios and does not quantify the necessary capacity and number of PMSGs. This paper newly proposes an analytical model to quantify the minimum number of the PMSGs for coordinated LVRT. The critical voltage at the point of common coupling (PCC) leading to slip instability of the IGs is quantified. To avoid instability, necessary var support from the …

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Low Leakage Power Gating Technique For Subnanometer Cmos Circuits, Kavitha Manickam, Govindaraj Thangavel Jan 2016

Low Leakage Power Gating Technique For Subnanometer Cmos Circuits, Kavitha Manickam, Govindaraj Thangavel

Turkish Journal of Electrical Engineering and Computer Sciences

Static power has become the most important factor in the fabrication of integrated circuits. Power gating techniques minimize leakage currents and help to develop ultra-low-power and high-performance digital circuits. In this paper, a power gating approach is proposed to minimize leakage for subnanometer technologies. Simulation results reveal that the proposed technique reduces maximum of 96% leakage power, 33% dynamic power, 49% drowsy power, and 16{\%} energy as compared to conventional techniques. The proposed technique offers good leakage reduction, even under variation of different operating parameters.

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A New Algorithm For Avoiding Maloperation Of Transformer Restricted Earth Fault Protection Caused By The Transformer Magnetizing Inrush Current And Current Transformer Saturation, Jelisaveta Krstivojevic, Milenko Djuric Jan 2016

A New Algorithm For Avoiding Maloperation Of Transformer Restricted Earth Fault Protection Caused By The Transformer Magnetizing Inrush Current And Current Transformer Saturation, Jelisaveta Krstivojevic, Milenko Djuric

Turkish Journal of Electrical Engineering and Computer Sciences

Owing to current transformer (CT) saturation caused by a decaying direct current component in the magnetizing inrush current, the restricted earth fault (REF) protection of a power transformer could maloperate during magnetizing inrush. This paper presents a new transformer restricted earth fault relay algorithm that can prevent false relay tripping and provide proper action during the energization of a faulty transformer. The integral of the product of the signals that are compared is calculated over 1 half-period of the signals. The performance of the proposed algorithm is tested and verified using a large number of transformer energization trials and fault …

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Interference In Geoelectric Field Observation From The Current Of A Direct-Current Grounding Electrode, Bo Tang, Zhuo Wu, Ren Liu, Shuang Wang, Qixiang Lin Jan 2016

Interference In Geoelectric Field Observation From The Current Of A Direct-Current Grounding Electrode, Bo Tang, Zhuo Wu, Ren Liu, Shuang Wang, Qixiang Lin

Turkish Journal of Electrical Engineering and Computer Sciences

The existence of ultrahigh voltage direct-current (UHVDC) transmission lines impacts geoelectric field observation (GFO), which further disturbs earthquake observation and prediction. We proposed a mathematic method based on a 3-dimensional layered soil model to calculate the interference and conducted GFO experiments at observatories and field observation sites during the live debugging of a $\pm $800 kV UHVDC transmission line to verify the method. The results obtained by using the proposed method are in good accordance with the experimental results and the maximum error is no more than 15%. Moreover, the experiment proves that grounding current is a decisive factor in …

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Fpga Implementations Of Scale-Invariant Models Of Neural Networks, Zeinulla Zhanabaev, Yeldos Kozhagulov, Dauren Zhexebay Jan 2016

Fpga Implementations Of Scale-Invariant Models Of Neural Networks, Zeinulla Zhanabaev, Yeldos Kozhagulov, Dauren Zhexebay

Turkish Journal of Electrical Engineering and Computer Sciences

Integrated circuit implementations of new models of neural networks with scale-invariant properties are presented. The specifics of such models are necessary in analysis of discrete mappings containing fractional power. We suggest an algorithm for increasing the power of a physical value by using a field-programmable gate array (FPGA). Comparisons between FPGA implementations and numerical results are demonstrated.

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A Sampling-Based Method Using An Improved Nonparametric Density Estimator For Probabilistic Harmonic Load Flow Calculation, Farshid Nasrfard-Jahromi, Mohammad Mohammadi Jan 2016

A Sampling-Based Method Using An Improved Nonparametric Density Estimator For Probabilistic Harmonic Load Flow Calculation, Farshid Nasrfard-Jahromi, Mohammad Mohammadi

Turkish Journal of Electrical Engineering and Computer Sciences

Harmonic distortion in electrical power systems is responsible for several technical problems. Harmonic load flow (HLF) methods have been employed in order to predict and solve many of the problems from a deterministic point of view. Moreover, methods based on probability theory have been developed to deal with the uncertainties in power systems and the random nature of harmonics. Unfortunately, since many of these methods are based on linearized models or some simplifying assumptions, they do not have acceptable accuracy. This paper proposes the use of an efficient sampling method, median Latin hypercube sampling, combined with an improved kernel density …

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Design And Implementation Of A Digital Mppt Controller For A Photovoltaic Panel, Djamel Eddine Tourqui, Achour Betka, Atallah Smaili, Tayeb Allaoui Jan 2016

Design And Implementation Of A Digital Mppt Controller For A Photovoltaic Panel, Djamel Eddine Tourqui, Achour Betka, Atallah Smaili, Tayeb Allaoui

Turkish Journal of Electrical Engineering and Computer Sciences

This paper proposes a simplified design and hardware implementation of a digital maximum power point tracking (MPPT) controller for a photovoltaic (PV) panel using PIC microcontroller 16F877A embedded technology. The 3 most well-known algorithms, perturb & observe, hill-climbing, and incremental conductance, are considered and analyzed from a practical implementation point of view. The control board was developed using simple circuits and tested under resistive load conditions lower than the load of the maximum power point. The MPPT controller proved its effectiveness, providing maximum power to the load under changing weather conditions.

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Parallel Decoding For Lattice Reduction-Aided Mimo Receiver, Madurakavi Karthikeyan, Djagadeesan Saraswady Jan 2016

Parallel Decoding For Lattice Reduction-Aided Mimo Receiver, Madurakavi Karthikeyan, Djagadeesan Saraswady

Turkish Journal of Electrical Engineering and Computer Sciences

In this paper, we propose a modified lattice reduction (LR) for parallel decoding (PD) in multiple input and multiple output (MIMO) systems. Compared with the conventional methods, without any performance loss, the symbols can be estimated in parallel using this LR-PD algorithm. This parallel decoding is achieved through the proposed postrotation matrix. Among the various LR algorithms, LLL has been considered in the analysis of this postrotation matrix. However, this can be applied to any other LR algorithms without any modifications. In simulations, we show that with a minimal number of extra arithmetic operations and without any significant loss in …

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Thermal Aging Of Solid Insulation Under Dual Temperature Variation, Amit Kumar Mehta, Ram Naresh Sharma, Sushil Chauhan Jan 2016

Thermal Aging Of Solid Insulation Under Dual Temperature Variation, Amit Kumar Mehta, Ram Naresh Sharma, Sushil Chauhan

Turkish Journal of Electrical Engineering and Computer Sciences

The power transformer is one of the most expensive pieces of equipment in a high-voltage AC power system. An adequate monitoring system for power transformers can help in reducing the failure rate and thereby enhance system reliability and economic efficiency. Long-term and accelerated aging is not possible in real transformers, so prorated models of real transformers are preferred. This paper presents a study aimed at the aging of different cellulose papers and pressboards impregnated with transformer oil subjected to accelerated thermal aging at an oil temperature of 120 $^{\circ}$C and winding temperature of 150 $^{\circ}$C for time intervals extending from …

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An Optimized Embedded Adder For Digital Signal Processing Applications, Kala Bharathan, Seshasayanan Ramachandran Jan 2016

An Optimized Embedded Adder For Digital Signal Processing Applications, Kala Bharathan, Seshasayanan Ramachandran

Turkish Journal of Electrical Engineering and Computer Sciences

In this paper, an embedded logic full adder (PRO-FA) circuit in transistor level is proposed that reduces logic complexity, consumes low power, and is low area. The design is implemented for 1 bit and then is further extended to 64 bits. The area obtained for 1-bit PRO-FA is 2.85 $ {\mu }{m}^{{2}}$ and is built using only 13 transistors. The PDP of the proposed adder is ${459.4\times }{{10}}^{{-18}} Ws $ and ADP is 128.25 $\mu {m}^{{2}}ps $ and is compared with the earlier reported designs. Furthermore, a 16-, 32-, 64-bit both linear and square-root carry select adder/subtractor (CSLAS) structure is …

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The Parallel Resonance Impedance Detection Method For Parameter Estimation Of Power Line And Transformer By Using Csa, Ga, And Pso, Bahadir Akbal, Abdullah Ürkmez Jan 2016

The Parallel Resonance Impedance Detection Method For Parameter Estimation Of Power Line And Transformer By Using Csa, Ga, And Pso, Bahadir Akbal, Abdullah Ürkmez

Turkish Journal of Electrical Engineering and Computer Sciences

Power line parameters are an important factor in relay applications and power quality studies. In the literature, the phasor measurement unit method and measuring of current and voltage at two ends of the power line were usually used to estimate the power line parameters. In this study, the parallel resonance impedance detection method was used to estimate the power line parameter to obtain input data. The real measurement values are used to obtain parallel resonance impedance in this method. The real measurement values include the measurement errors of the current and voltage transformer. Thus, the estimated parameter values are realistic. …

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A New Method To Reduce The Adverse Effects Of Wind Power On Power Quality Using Reactive Power Compensating Capacitors, Seyed Navid Zahedi, Amir Amini, Hamid Falaghi Jan 2016

A New Method To Reduce The Adverse Effects Of Wind Power On Power Quality Using Reactive Power Compensating Capacitors, Seyed Navid Zahedi, Amir Amini, Hamid Falaghi

Turkish Journal of Electrical Engineering and Computer Sciences

The usage of distributed generation resources, particularly distributed generation with renewable sources, has increased to generate electrical power close to consumers. One of the factors that can reduce penetration of distributed generation resources is the limitation of power quality, such as harmonic distortions. Distributed generation sources, in addition to producing power, due to using of power electronic converters and changing the power flow, increase harmonic currents. On the other hand, local compensation of reactive power by parallel capacitor banks is one of the effective methods to reduce power system losses and harmonic distortions. Since the capacitor impedance varies at different …

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Stochastic Congestion Management Considering Power System Uncertainties: A Chance-Constrained Programming Approach, Mehrdad Hojjat, Mohammad Hossein Javidi, Dariush Yazdanpanah Jan 2016

Stochastic Congestion Management Considering Power System Uncertainties: A Chance-Constrained Programming Approach, Mehrdad Hojjat, Mohammad Hossein Javidi, Dariush Yazdanpanah

Turkish Journal of Electrical Engineering and Computer Sciences

Considering system uncertainties in developing power systems, algorithms such as congestion management (CM) are vital in power system analysis and studies. This paper proposes a new model for power system CM by considering power system uncertainties based on chance-constrained programming (CCP). In the proposed approach, transmission constraints are taken into account by stochastic, instead of deterministic, models. The proposed approach considers network uncertainties with a specific level of probability in the optimization process, and then an analytical approach is used to solve the new model of stochastic congestion management. In this approach, the stochastic optimization problem is transformed into an …

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Highly Efficient Three-Phase Three-Level Multilevel Inverter Employing Different Commutation Strategies, Ammar Masaoud, Hew Wooi Ping, Saad Mekhilef, Hamza Belkamel Jan 2016

Highly Efficient Three-Phase Three-Level Multilevel Inverter Employing Different Commutation Strategies, Ammar Masaoud, Hew Wooi Ping, Saad Mekhilef, Hamza Belkamel

Turkish Journal of Electrical Engineering and Computer Sciences

This paper introduces a new three-phase three-level voltage source inverter. The proposed topology constitutes the conventional three-phase two-level inverter with three bidirectional switches. For purpose of generating the appropriate switching gate signals, two different commutation strategies are suggested and analyzed. A comparison between both strategies in terms of power losses and efficiency are presented. To ensure the feasibility of the proposed configuration with its suggested commutation strategies, the prototype of the proposed inverter was manufactured and the experimental results are given.

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Estimating And Reshaping Human Intention Via Human--Robot Interaction, Aki̇f Durdu, İsmet Erkmen, Aydan Müşerref Erkmen Jan 2016

Estimating And Reshaping Human Intention Via Human--Robot Interaction, Aki̇f Durdu, İsmet Erkmen, Aydan Müşerref Erkmen

Turkish Journal of Electrical Engineering and Computer Sciences

Human--robot interaction (HRI) is studied in two important research areas, intention estimation and intention reshaping. Although there are many studies in the literature that define human intention, new research examines the reshaping of human intentions by using robots in HRI. In this paper, 2 different robot movements are tested in a real environment in order to reshape current human intention. The hidden Markov model (HMM) is used to estimate human intention in our intelligent robotic system. The algorithmic design of the system comprises 2 parts: the first part tracks the moving objects in the environment, and the second part estimates …

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Amplitude-Phase Control Of A Novel Chaotic Attractor, Chunbiao Li, İhsan Pehli̇van, Julien Clinton Sprott Jan 2016

Amplitude-Phase Control Of A Novel Chaotic Attractor, Chunbiao Li, İhsan Pehli̇van, Julien Clinton Sprott

Turkish Journal of Electrical Engineering and Computer Sciences

A novel chaotic attractor with a fractal wing structure is proposed and analyzed in terms of its basic dynamical properties. The most interesting feature of this system is that it has complex dynamical behavior, especially coexisting attractors for particular ranges of the parameters, including two coexisting periodic or strange attractors that can coexist with a third strange attractor. Amplitude and phase control methods are described since they are convenient for circuit design and chaotic signal applications. An appropriately chosen parameter in a particular quadratic coefficient can realize partial amplitude control. An added linear term can change the symmetry and provide …

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An 11-Switch Multilevel Inverter With A Modified Space Vector Modulation, Nasrudin Abd Rahim, Hew Wooi Ping, Jafferi Jamaludin Jan 2016

An 11-Switch Multilevel Inverter With A Modified Space Vector Modulation, Nasrudin Abd Rahim, Hew Wooi Ping, Jafferi Jamaludin

Turkish Journal of Electrical Engineering and Computer Sciences

This paper proposes a new 3-phase multilevel inverter that is able to generate 7 levels in line-to-line voltage with only 11 switches. The inverter is formed from the 6-switch conventional full-bridge topology with the addition of 5 bidirectional switches in which 2 of them are shared among the three phases. By doing so, the number of power switches can be minimized, thus reducing the complexity in generating and controlling PWM signals. A novel voltage control scheme based on space vector modulation is developed by introducing a virtual vector in every sector of the vector hexagon. This is to overcome the …

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Rlc Circuit Extraction With The Differential Evolution Algorithm For Conducted Electromagnetic Emission Model Of Integrated Circuits, Muhammed Emi̇n Başak, Ayten Kuntman Jan 2016

Rlc Circuit Extraction With The Differential Evolution Algorithm For Conducted Electromagnetic Emission Model Of Integrated Circuits, Muhammed Emi̇n Başak, Ayten Kuntman

Turkish Journal of Electrical Engineering and Computer Sciences

This paper examines the modeling of conducted electromagnetic emissions of integrated circuits. In this study, test circuits were designed and printed circuit boards were prepared to measure the input impedance at the power supply pin of the microcontroller. After S-parameter measurements of the test circuit were performed in a frequency range of 10 MHz to 2 GHz, Z-parameters were obtained via S-parameters. Next, the impedance--frequency curve of the test circuit's power supply pin, which consists of a microcontroller core, printed circuit board, conductive trace, and SMA connector global impedances, was obtained. Therefore, all the traces, printed circuit board, and SMA …

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A Robust Estimator-Based Optimal Algebraic Approach To Steam Generator Feedwater Control System, Günyaz Ablay Jan 2016

A Robust Estimator-Based Optimal Algebraic Approach To Steam Generator Feedwater Control System, Günyaz Ablay

Turkish Journal of Electrical Engineering and Computer Sciences

Feedwater control systems are used to maintain the steam generator water level within prescribed narrow limits and to provide constant supply of steam during power demand variations. Current feedwater control systems are often found to be unsatisfactory during startup and low power operations. A robust nonlinear estimator-based optimal algebraic control is developed for feedwater control systems to solve the water level tracking problem during power demand variations. It is shown that the proposed control provides an optimal and robust water level tracking with a single automatic controller over the complete range of power operations in the presence of plant uncertainties …

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A Gis-Based Novel Active Monitoring System For Fiber Networks, Özer Koray Akdemi̇r, Taner Dursun, Sadik Arslan, Recep Benzer, Muhammet Ali̇ Akcayol Jan 2016

A Gis-Based Novel Active Monitoring System For Fiber Networks, Özer Koray Akdemi̇r, Taner Dursun, Sadik Arslan, Recep Benzer, Muhammet Ali̇ Akcayol

Turkish Journal of Electrical Engineering and Computer Sciences

In this study, a geographic information system (GIS)-based novel fiber network monitoring system has been developed to improve the operation and maintenance of fiber optic networks (FONs). The main aim of the developed system is to provide the required capabilities for both detailed digital modeling and central monitoring of FONs. The system can perform scheduled measurements and dispatch alarms if any fault or degradation is detected in the concerned FON. It also indicates the alarm locations on a map as a considerable contribution to decreasing mean time to repair. The developed monitoring system has more security features than others.

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Modeling Based On 3d Finite Element Analysis And Experimental Study Of A 24-Slot 8-Pole Axial-Flux Permanent-Magnet Synchronous Motor For No Cogging Torque And Sinusoidal Back-Emf, Mehmet Güleç, Ersi̇n Yolaçan, Yücel Demi̇r, Oğuzhan Ocak, Meti̇n Aydin Jan 2016

Modeling Based On 3d Finite Element Analysis And Experimental Study Of A 24-Slot 8-Pole Axial-Flux Permanent-Magnet Synchronous Motor For No Cogging Torque And Sinusoidal Back-Emf, Mehmet Güleç, Ersi̇n Yolaçan, Yücel Demi̇r, Oğuzhan Ocak, Meti̇n Aydin

Turkish Journal of Electrical Engineering and Computer Sciences

This paper discusses cogging torque minimization techniques in surface-mounted, axial-flux, multirotor permanent magnet synchronous disc motors in order to eliminate cogging components and obtain sinusoidal back-EMF for low-speed applications. Cogging torque minimization techniques are examined in detail with a focus on magnet skewing and pole and rotor shifting in order to obtain zero cogging. Some magnet shape and rotor design alternatives with conventional skew planar magnets were investigated based on 3D finite element analysis (FEA). Improvements compared to unskewed reference axial-flux permanent magnet (AFPM) motor design are presented. A prototype AFPM motor was built and tested based on the analyses. …

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The Classification Of Eeg Signals Using Discretization-Based Entropy And The Adaptive Neuro-Fuzzy Inference System, Mahmut Heki̇m Jan 2016

The Classification Of Eeg Signals Using Discretization-Based Entropy And The Adaptive Neuro-Fuzzy Inference System, Mahmut Heki̇m

Turkish Journal of Electrical Engineering and Computer Sciences

A novel feature extraction called discretization-based entropy is proposed for use in the classification of EEG signals. To this end, EEG signals are decomposed into frequency subbands using the discrete wavelet transform (DWT), the coefficients of these subbands are discretized into the desired number of intervals using the discretization method, the entropy values of the discretized subbands are calculated using the Shannon entropy method, and these are then used as the inputs of the adaptive neuro-fuzzy inference system (ANFIS). The equal width discretization (EWD) and equal frequency discretization (EFD) methods are used for the discretization. In order to evaluate their …

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Linear Model Of A Three-Phase Shunt Active Power Filter With A Hysteresis Controller, Kadi̇r Vardar, Eyup Akpinar Jan 2016

Linear Model Of A Three-Phase Shunt Active Power Filter With A Hysteresis Controller, Kadi̇r Vardar, Eyup Akpinar

Turkish Journal of Electrical Engineering and Computer Sciences

In this work, a linear model of a 3-phase active power filter (APF) is obtained to design a DC link proportional--integral (PI) controller. The system is designed on the basis of a TMS320F2812 digital signal processer (DSP). The PI controller is implemented in the program of the DSP. The hysteresis controller and sampling frequency are also taken into account in the linear model. The effect of hysteresis bandwidth, filter inductance, DC link capacitor, and sampling frequency on the stability are investigated by using the Routh--Hurwitz method. The detailed simulation model in MATLAB and experimental results showed that the linear model …

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A Sparsity-Preserving Spectral Preconditioner For Power Flow Analysis, Emrullah Fati̇h Yetki̇n, Hasan Dağ Jan 2016

A Sparsity-Preserving Spectral Preconditioner For Power Flow Analysis, Emrullah Fati̇h Yetki̇n, Hasan Dağ

Turkish Journal of Electrical Engineering and Computer Sciences

Due to the ever-increasing demand for more detailed and accurate power system simulations, the dimensions of mathematical models increase. Although the traditional direct linear equation solvers based on LU factorization are robust, they have limited scalability on the parallel platforms. On the other hand, simulations of the power system events need to be performed at a reasonable time to assess the results of the unwanted events and to take the necessary remedial actions. Hence, to obtain faster solutions for more detailed models, parallel platforms should be used. To this end, direct solvers can be replaced by Krylov subspace methods (conjugate …

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A Switchable Approach To Large Object Allocation In Real-Time Java, Veysel Harun Şahi̇n, Ümi̇t Kocabiçak Jan 2016

A Switchable Approach To Large Object Allocation In Real-Time Java, Veysel Harun Şahi̇n, Ümi̇t Kocabiçak

Turkish Journal of Electrical Engineering and Computer Sciences

Over the last 20 years object-oriented programming languages and managed run-times like Java have been very popular because of their software engineering benefits. Despite their popularity in many application areas, they have not been considered suitable for real-time programming. Besides many other factors, one of the barriers that prevent their acceptance in the development of real-time systems is the long pause times that may arise during large object allocation. This paper examines different kinds of solutions that have been developed so far and introduces a switchable approach to large object allocation in real-time Java. A synthetic benchmark application that is …

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Extracting The Region Of Interest From Mfl Signals, Ali Sadr, Raziyeh Sadat Okhovat Jan 2016

Extracting The Region Of Interest From Mfl Signals, Ali Sadr, Raziyeh Sadat Okhovat

Turkish Journal of Electrical Engineering and Computer Sciences

In this paper, we study the magnetic flux leakage (MFL) signals for detection of defects in ferromagnetic materials. MFL signals consist of a background that is not constant and is combined with noise. Since there are slight variations because of noise, any large distortion shows a defect. Here the estimation of the background and then the determination of a threshold to distinguish defects from noise have been used for locating defects. In this method, precise evaluation of these two parameters has a vital role on the defect detection. The concept of histograms has been employed for eliminating the effect of …

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