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Articles 7351 - 7380 of 13049

Full-Text Articles in Computer Engineering

A 2-D Analytical Model For Cylindrical Gate Tunnel Fet (Cg-Tfet) Based On Center Potential, Sidhartha Dash, Guru Prasad Mishra Jan 2017

A 2-D Analytical Model For Cylindrical Gate Tunnel Fet (Cg-Tfet) Based On Center Potential, Sidhartha Dash, Guru Prasad Mishra

Turkish Journal of Electrical Engineering and Computer Sciences

In this paper, a 2-D cylindrical gate tunnel FET (CG-TFET) model is developed based on the potential at the center of cylinder. The center potential is obtained by Laplace solution in the cylindrical coordinate system and the accuracy is validated using a 2-D TCAD device simulator. The tunneling of charge carriers in the CG-TFET is analyzed using the center potential and the results are compared to the surface potential-based model. The drain current is formulated using the initial tunneling point and tunneling path, which further helps to obtain the threshold voltage of this model. The effect of gate engineering and …

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Full Occlusion Handling For Pedestrian Tracking Via Hybrid System, Xiaoyu Zhang, Shiqiang Hu, Huanlong Zhang, Xing Hu Jan 2017

Full Occlusion Handling For Pedestrian Tracking Via Hybrid System, Xiaoyu Zhang, Shiqiang Hu, Huanlong Zhang, Xing Hu

Turkish Journal of Electrical Engineering and Computer Sciences

Occlusion and lack of visibility even in sparse crowd scenes make it difficult to track individual pedestrians correctly and consistently, particularly in a single view. We present a novel pedestrian tracking approach that connects tracking with reidentification to locate and maintain the identity of certain people who may be occluded for a long time. First, two models are constructed. One model tracks the pedestrian and trains a classifier, while the other model reidentifies the pedestrian of interest from detection results with the trained classifier. Secondly, we design a set of transition rules for model switching. Finally, the two models work …

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A Novel Direct Torque Control Using Second Order Continuous Sliding Mode Of A Doubly Fed Induction Generator For A Wind Energy Conversion System, Zinelaabidine Boudjema, Rachid Taleb, Youcef Djeriri, Adil Yahdou Jan 2017

A Novel Direct Torque Control Using Second Order Continuous Sliding Mode Of A Doubly Fed Induction Generator For A Wind Energy Conversion System, Zinelaabidine Boudjema, Rachid Taleb, Youcef Djeriri, Adil Yahdou

Turkish Journal of Electrical Engineering and Computer Sciences

In this paper a new robust direct torque control strategy based on second order continuous sliding mode and space vector modulation of a doubly fed induction generator integrated in a wind energy conversion system is presented. The conventional direct torque control (C-DTC) with hysteresis regulators has significant flux and torque ripples at steady-state operation and also the switching frequency varies in a wide range. The proposed DTC technique based on second order continuous sliding mode control reduces flux, current, and torque ripples. It also narrows down the switching frequency variations in induction machine control. Two different sliding surfaces such as …

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A Methodology To Include Real-Life Failure Data In The Failure Rate Estimation Of Power Distribution Systems, Mojtaba Gilvanejad, Hossein Askarian Abyaneh, Kazem Mazlumi Jan 2017

A Methodology To Include Real-Life Failure Data In The Failure Rate Estimation Of Power Distribution Systems, Mojtaba Gilvanejad, Hossein Askarian Abyaneh, Kazem Mazlumi

Turkish Journal of Electrical Engineering and Computer Sciences

Random failure rates are usually assumed as constant values in reliability calculations. In this paper, this topic is investigated using stochastic models of uncertain phenomena like lightning, cold load pickup, and overloading, which result in random failures. An algorithm is developed to estimate the random failure rates in distribution networks during their lifetime. This algorithm stochastically generates the random failures as well as sustained failures as a result of equipment wear-out state due to the aging process and finally estimates the total number of temporary/sustained failures in a period of the network lifetime. The results of applying this algorithm to …

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Experimental Evaluation And Fdtd Method For Predicting Electromagnetic Fields In The Near Zone Radiated By Power Converter Systems, Mohammed Laour, Redouane Tahmi, Christian Vollaire Jan 2017

Experimental Evaluation And Fdtd Method For Predicting Electromagnetic Fields In The Near Zone Radiated By Power Converter Systems, Mohammed Laour, Redouane Tahmi, Christian Vollaire

Turkish Journal of Electrical Engineering and Computer Sciences

This paper presents the study of conducted electromagnetic interference (EMI) currents flowing through the power cables of a DC-DC converter system and its correlation with the near field radiated from these cables. The radiated emission measurement contains a common mode (CM) and a differential mode (DM), and accurate separation of the radiated emissions of these two modes is necessary. The finite-difference time-domain (FDTD) method is used to predict the electromagnetic radiation caused by CM currents and DM currents. An experimental bench has been designed to allow access to the measurement of EMI disturbances at various sensitive places. The CM and …

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Whole Body Motion Control Of Humanoid Robots Using Bilateral Control, Emre Sariyildiz, Hakan Temeltaş Jan 2017

Whole Body Motion Control Of Humanoid Robots Using Bilateral Control, Emre Sariyildiz, Hakan Temeltaş

Turkish Journal of Electrical Engineering and Computer Sciences

This paper deals with the whole body motion control problem of humanoid robots by using automatic and bilateral control methods. Advanced motion controllers are proposed so that human daily life activities, such as walking on an uneven terrain and contacting an unknown object, can be performed. It is shown that the uncertainty of environmental impedance variation is one of the main challenging issues in the design of the automatic control systems, i.e. a humanoid robot may easily lose its stability when it contacts an unstructured environment. A novel bilateral control method is proposed for humanoid robots so as to overcome …

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Ionolab-Ray: A Wave Propagation Algorithm For Anisotropic And Inhomogeneous Ionosphere, Esra Erdem, Feza Arikan Jan 2017

Ionolab-Ray: A Wave Propagation Algorithm For Anisotropic And Inhomogeneous Ionosphere, Esra Erdem, Feza Arikan

Turkish Journal of Electrical Engineering and Computer Sciences

A high-frequency (HF) radio wave propagation model based on ray tracing for anisotropic, inhomogeneous, and time-varying ionosphere is developed to form the basis for a user-friendly modular algorithm. The algorithm IONOLAB-RAY applies the principles of ray tracing through the spherical 3D grid model of the ionosphere. The physical parameters of the ionosphere in each voxel are obtained from the ionosphere model IRI-Plas-G. The refractive index of each voxel is calculated with the Appleton-Hartree formula, which includes electron cyclotron frequency, collision frequency, and anisotropicity due to the geomagnetic field. The developed propagation algorithm allows the input of total electron content (TEC) …

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Optimal Design Of Voltage Regulators For Static Excitation System In Synchronous Generator To Reduce Shaft-Induced Voltage, Mahmoud Samieimoghaddam, Mohammad Tavakoli Bina, Masoud Aliakbar Golkar, Shokrollah Shokrikojoori Jan 2017

Optimal Design Of Voltage Regulators For Static Excitation System In Synchronous Generator To Reduce Shaft-Induced Voltage, Mahmoud Samieimoghaddam, Mohammad Tavakoli Bina, Masoud Aliakbar Golkar, Shokrollah Shokrikojoori

Turkish Journal of Electrical Engineering and Computer Sciences

Long-term shaft-induced voltage could harm synchronous generators, specifically their bearings and insulators. This paper investigates the reduction of shaft-induced voltage using both a passive filter and an active voltage regulator. An RLC circuit is used as a passive filter, and a DC-DC buck converter is used as an active voltage regulator. As a result, they remove high-frequency spikes, leading to the reduction of shaft-induced voltage. Buck converters show minimum-phase behavior and can pose as stable-casual converters. A 5 kW synchronous generator was considered for the laboratory setup in which a static excitation system using a 6-pulse thyristor rectifier supplies the …

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Intrusion Detection In Network Flows Based On An Optimized Clustering Criterion, Jaber Karimpour, Shahriar Lotfi, Aliakbar Tajari Siahmarzkooh Jan 2017

Intrusion Detection In Network Flows Based On An Optimized Clustering Criterion, Jaber Karimpour, Shahriar Lotfi, Aliakbar Tajari Siahmarzkooh

Turkish Journal of Electrical Engineering and Computer Sciences

Graph-based intrusion detection approaches consider the network as a graph and detect anomalies based on graph metrics. However, most of these approaches succumb to the cluster-based behavior of the anomalies. To resolve this problem in our study, we use flow and graph-clustering concepts to create a data set first. A new criterion related to the average weight of clusters is then defined and a model is proposed to detect attacks based on the above-mentioned criterion. Finally, the model is evaluated using a DARPA data set. Results show that the proposed approach detects the attacks with high accuracy relative to methods …

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Techno-Economic Analysis Using Different Types Of Hybrid Energy Generation For Desert Safari Camps In Uae, Ali Aziz Jan 2017

Techno-Economic Analysis Using Different Types Of Hybrid Energy Generation For Desert Safari Camps In Uae, Ali Aziz

Turkish Journal of Electrical Engineering and Computer Sciences

Remote areas in UAE are still fully powered by diesel generators. The rapid rise in the prices of petroleum products and environmental concerns have led to demand for hybrid renewable energy generators. Advances in renewable energy technologies impart further impetus to techno-economic power production. Protecting the landscape and demography of the desert by optimizing the power supply cost via an efficient hybrid power system is the key issue. Simulation results on the cross utilization of a photovoltaic/wind/battery/fuel-cell hybrid-energy source to power the off-grid living space are presented. Simultaneous exploitation of different renewable energy sources to power off-grid applications together with …

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A Steganographic Approach To Hide Secret Data In Digital Audio Based On Xor Operands Triplet Property With High Embedding Rate And Good Quality Audio, Krishna Bhowal, Debasree Chanda Sarkar, Sushanta Biswas, Partha Pratim Sarkar Jan 2017

A Steganographic Approach To Hide Secret Data In Digital Audio Based On Xor Operands Triplet Property With High Embedding Rate And Good Quality Audio, Krishna Bhowal, Debasree Chanda Sarkar, Sushanta Biswas, Partha Pratim Sarkar

Turkish Journal of Electrical Engineering and Computer Sciences

In this paper, a unique and transparent data hiding algorithm based on XOR operands triplet (XOT) is proposed. In XOT, an XOR operation applied on any two members of a triplet provides the third member of the same triplet. Taking advantage of the low computational complexity and fascinating properties of the XOR operator, it is possible to embed 4-ary secret digits with negligible changes in the host digital audio. The proposed scheme has been designed to ensure that a minimum number of bit alterations happen in the host digital audio during the data hiding process, which also increases the security …

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A Neuro-Fuzzy Controller For Grid-Connected Heavy-Duty Gas Turbine Power Plants, Mohamed Iqbal Mohamed Mustafa, Joseph Xavier Rayappan, Kanakaraj Jagannathan Jan 2017

A Neuro-Fuzzy Controller For Grid-Connected Heavy-Duty Gas Turbine Power Plants, Mohamed Iqbal Mohamed Mustafa, Joseph Xavier Rayappan, Kanakaraj Jagannathan

Turkish Journal of Electrical Engineering and Computer Sciences

Frequent load fluctuation and set-point variation may affect the stability of grid-connected heavy-duty gas turbine power plants. To overcome such problems, a novel neuro-fuzzy controller is proposed in this paper for single-shaft heavy-duty gas turbines ranging from 18.2 MW to 106.7 MW. A neuro-fuzzy controller was developed using a hybrid learning algorithm and the effectiveness of the controller for all heavy-duty gas turbine plants (5, 6, 7, and 9 series) is demonstrated against load disturbance and set-point variation in a grid-connected environment. Various time domain specifications and performance index criteria of the neuro-fuzzy controller are compared with that of a …

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A Switched Current Controller With Commutation Delay Compensation For The Reduction Of Commutation Torque Ripple In Bldcm Drives, Türker Türker, Ihsan Obayes Khudhair Khudhair Jan 2017

A Switched Current Controller With Commutation Delay Compensation For The Reduction Of Commutation Torque Ripple In Bldcm Drives, Türker Türker, Ihsan Obayes Khudhair Khudhair

Turkish Journal of Electrical Engineering and Computer Sciences

The mathematical model of the equivalent circuit of a brushless DC motor switches during the operation due to commutation. This issue causes a sudden ripple in the output torque, which is called commutation torque ripple. Brushless DC motor drives suffer from commutation torque ripple, affecting the performance of the motor in practical applications. A discrete-time switched controller is proposed to reduce the commutation torque ripple in brushless DC motor drives. The proposed controller is a combination of two distinct controllers designed for two different working regions of brushless DC motors. In addition, the commutation delay is also considered in the …

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Extraction Of Geometric And Prosodic Features From Human-Gait-Speech Data For Behavioral Pattern Detection: Part I, Raj Kumar Patra, Tilendra Shishir Sinha, Ravi Prakash Dubey Jan 2017

Extraction Of Geometric And Prosodic Features From Human-Gait-Speech Data For Behavioral Pattern Detection: Part I, Raj Kumar Patra, Tilendra Shishir Sinha, Ravi Prakash Dubey

Turkish Journal of Electrical Engineering and Computer Sciences

In this work, we extract prosodic features from subjects while they are talking while walking using human-gait-speech data. These human-gait-speech data are separated into 1D data (human-speech) and 2D data (human-gait) using the adaptive-lifting scheme of wavelet transform. We carry out extraction of prosodic features from human-speech data, such as speech duration, pitch, speaking rate, and speech momentum, using five different natural languages (Hindi, Bengali, Oriya, Chhattisgarhi, and English) for the detection of behavioral patterns. These behavioral patterns form real-valued measured parameters, stored in a knowledge-based model called the human-gait-speech model. Extraction of geometrical features from human-gait data, such as …

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Temporal Preconditioners For Marching-On-In-Time-Based Time Domain Integral Equation Solvers, Hüseyi̇n Arda Ülkü Jan 2017

Temporal Preconditioners For Marching-On-In-Time-Based Time Domain Integral Equation Solvers, Hüseyi̇n Arda Ülkü

Turkish Journal of Electrical Engineering and Computer Sciences

Temporal preconditioners to stabilize the marching-on-in-time (MOT)-based time domain integral equation (TDIE) solvers are proposed. Exponentially decaying functions are used as temporal preconditioners and the proposed scheme is applied to analyze scattering from perfect electrically conducting objects using the second-order formulation. The effectiveness of the proposed scheme is demonstrated via numerical examples. It is shown that the temporal preconditioners stabilize the MOT system and the solution. In addition, the initial condition problem of TDIEs is investigated by extending the second-order formulation of the time domain electric field integral equation to the time domain magnetic and combined field integral equations.

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Fuzzy Support Vector Machine Based On Hyperbolas Optimized By The Quantum-Inspired Gravitational Search Algorithm, Feng Ni, Yuzhu He, Fei Jiang Jan 2017

Fuzzy Support Vector Machine Based On Hyperbolas Optimized By The Quantum-Inspired Gravitational Search Algorithm, Feng Ni, Yuzhu He, Fei Jiang

Turkish Journal of Electrical Engineering and Computer Sciences

Fuzzy support vector machines (FSVMs) are known for their excellent antinoise performance, but there is no general rule when the fuzzy membership function (FMF) is set up. A novel FSVM based on hyperbolas optimized by the quantum-inspired gravitational search algorithm (QGSH-FSVM) is proposed to handle this question. In the proposed QGSH-FSVM, the FMF is defined by two disparate hyperbolas, whose eccentricities are optimized by the quantum-inspired gravitational search algorithm. A variable called diversity, revealing the percentage of a sample in different classes, is proposed to distinguish outliers or noises from valid samples. Experimental results confirm that the QGSH-FSVM is able …

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Bandwidth Allocation For Multiple Iptv Users Sharing The Same Link: A Case Study Of Telecom Of Kosovo, Arianit Maraj, Adrian Shehu, Dardan Maraj, Ruzhdi Sefa Jan 2017

Bandwidth Allocation For Multiple Iptv Users Sharing The Same Link: A Case Study Of Telecom Of Kosovo, Arianit Maraj, Adrian Shehu, Dardan Maraj, Ruzhdi Sefa

Turkish Journal of Electrical Engineering and Computer Sciences

Almost all operators today are facing constant requests for multiple video services in a single household. In these situations, video services have to compete for finite network bandwidth and other equipment resources. Each of them requires different bandwidth capacities. This dynamic behavior can jeopardize both quality of service and quality of experience. One should keep in mind that some video channels require more bandwidth than others. Telecom of Kosovo (TK) is facing the same issues. The encoders at TK are not scalable and they treat all video streams equally, without taking into consideration the fact that some video streams require …

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Effect Of Uniform And Dolph-Chebyshev Excitations On The Performance Of Circular Array Antennas, Mohan Kachalai Narasimman, Yogesh Kumar Choukiker, Srinivasa Rao Zinka, Kannadassan Dhanaraj Jan 2017

Effect Of Uniform And Dolph-Chebyshev Excitations On The Performance Of Circular Array Antennas, Mohan Kachalai Narasimman, Yogesh Kumar Choukiker, Srinivasa Rao Zinka, Kannadassan Dhanaraj

Turkish Journal of Electrical Engineering and Computer Sciences

This paper presents the design and simulation of microstrip circular antenna arrays and studies the effect of excitation with uniform and Dolph--Chebyshev distribution. With side lobe level of 20 dB and 8 microstrip circular patches, the circular array has been demonstrated with minimum grating lobes. The effects of patch and antenna array length on directivity, radiation patterns, and side lobe are also studied in detail. It is found that these antenna arrays are suitable for radar application.

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S-Visibility Problem In Vlsi Chip Design, Marzieh Eskandari, Mahdieh Yeganeh Jan 2017

S-Visibility Problem In Vlsi Chip Design, Marzieh Eskandari, Mahdieh Yeganeh

Turkish Journal of Electrical Engineering and Computer Sciences

In this paper, a new version of very large scale integration (VLSI) layouts compaction problem is considered. Bar visibility graph (BVG) is a simple geometric model for VLSI chip design and layout problems. In all previous works, vertical bars or other chip components in the plane model gates, as well as edges, are modeled by horizontal visibilities between bars. In this study, for a given set of vertical bars, the edges can be modeled with orthogonal paths known as staircases. Therefore, we consider a new version of bar visibility graphs (BsVG). We then present an algorithm to solve the s-visibility …

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Ann-Based Shepwm Using A Harmony Search On A New Multilevel Inverter Topology, Fayçal Chabni, Rachid Taleb, M'Hamed Helaimi Jan 2017

Ann-Based Shepwm Using A Harmony Search On A New Multilevel Inverter Topology, Fayçal Chabni, Rachid Taleb, M'Hamed Helaimi

Turkish Journal of Electrical Engineering and Computer Sciences

This article presents the application of the harmony search (HS) optimization algorithm for selective harmonic elimination PWM (SHEPWM) in a new topology of multilevel inverters with reduced number of electronic switching elements. The main objective of the harmonic elimination strategy is eliminating undesired low-rank harmonics in order to improve the quality of the output waveform. The harmonic elimination strategy is achieved by solving a system of nonlinear equations. In this paper harmony search optimization is applied using artificial neural networks (ANNs) on a new 21-level inverter topology. The algorithm is based on a music improvisation process. MATLAB programming software is …

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A Machine Learning Approach For Enhancing Security And Quality Of Service Of Optical Burst Switching Networks, Adel Dabash A. Rajab Jan 2017

A Machine Learning Approach For Enhancing Security And Quality Of Service Of Optical Burst Switching Networks, Adel Dabash A. Rajab

Theses and Dissertations

The Optical Bust Switching (OBS) network has become one of the most promising switching technologies for building the next-generation of internet backbone infrastructure. However, OBS networks still face a number of security and Quality of Service (QoS) challenges, particularly from Burst Header Packet (BHP) flooding attacks. In OBS, a core switch handles requests, reserving one of the unoccupied channels for incoming data bursts (DB) through BHP. An attacker can exploit this fact and send malicious BHP without the corresponding DB. If unresolved, threats such as BHP flooding attacks can result in low bandwidth utilization, limited network performance, high burst loss …

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Data Masking, Encryption, And Their Effect On Classification Performance: Trade-Offs Between Data Security And Utility, Juan C. Asenjo Jan 2017

Data Masking, Encryption, And Their Effect On Classification Performance: Trade-Offs Between Data Security And Utility, Juan C. Asenjo

CCAC Theses and Dissertations

As data mining increasingly shapes organizational decision-making, the quality of its results must be questioned to ensure trust in the technology. Inaccuracies can mislead decision-makers and cause costly mistakes. With more data collected for analytical purposes, privacy is also a major concern. Data security policies and regulations are increasingly put in place to manage risks, but these policies and regulations often employ technologies that substitute and/or suppress sensitive details contained in the data sets being mined. Data masking and substitution and/or data encryption and suppression of sensitive attributes from data sets can limit access to important details. It is believed …

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A Novel Ddcc+ Based First-Order Current-Mode Active-C All-Pass Filter Using A Grounded Capacitor, Remzi̇ Arslanalp Jan 2017

A Novel Ddcc+ Based First-Order Current-Mode Active-C All-Pass Filter Using A Grounded Capacitor, Remzi̇ Arslanalp

Turkish Journal of Electrical Engineering and Computer Sciences

In this study, a novel first-order current-mode active-C all-pass filter based on a companding idea is proposed. In the design of the filter, a state space method is used. The proposed structure consists of only two plus-type differential difference current conveyors, nine external MOSFETs, and a single grounded capacitor. The dominant advantages of the proposed filter are briefly described as follows: offering resistorless design, consuming low power, having an electronic tunability property of its pole frequency, and not suffering from the disadvantage of any passive component matching conditions. By cascading two all-pass filters in a closed negative feedback loop, a …

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A Novel Approach For Extracting Ideal Exemplars By Clustering For Massivetime-Ordered Datasets, Ömer Faruk Ertuğrul Jan 2017

A Novel Approach For Extracting Ideal Exemplars By Clustering For Massivetime-Ordered Datasets, Ömer Faruk Ertuğrul

Turkish Journal of Electrical Engineering and Computer Sciences

The number and length of massive datasets have increased day by day and this yields more complex machine learning stages due to the high computational costs. To decrease the computational cost many methods were proposed in the literature such as data condensing, feature selection, and filtering. Although clustering methods are generally employed to divide samples into groups, another way of data condensing is by determining ideal exemplars (or prototypes), which can be used instead of the whole dataset. In this study, first the efficiency of traditional data condensing by clustering approach was confirmed according to obtained accuracies and condensing ratios …

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Nonlinear Model Predictive Control Based On Fuzzy Wavelet Neural Network And Chaos Optimization, Mehrnoush Davanipour, Hanieh Asadipooya Jan 2017

Nonlinear Model Predictive Control Based On Fuzzy Wavelet Neural Network And Chaos Optimization, Mehrnoush Davanipour, Hanieh Asadipooya

Turkish Journal of Electrical Engineering and Computer Sciences

In this paper a combined controller is proposed for nonlinear dynamical systems. The controller is constructed by a fuzzy wavelet network and nonlinear model predictive control. Chaotic optimization, which is fast and robust, is applied to generate optimized controlled input in nonlinear model predictive control. The ability of the fuzzy wavelet neural network and the proposed controller is shown by simulation. It is illustrated that the proposed method is able to increase the speed of tracking in addition to having very little steady state error. Using chaotic optimization makes the controller robust in the presence of noise.

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A Reduced-Order Observer Based On Stator Flux Estimation With Straightforward Parameter Identification For Sensorless Control Of Dfigs, Rahim Ajabi Farshbaf, Mohammad Reza Azizian, Vahid Eslampanah Jan 2017

A Reduced-Order Observer Based On Stator Flux Estimation With Straightforward Parameter Identification For Sensorless Control Of Dfigs, Rahim Ajabi Farshbaf, Mohammad Reza Azizian, Vahid Eslampanah

Turkish Journal of Electrical Engineering and Computer Sciences

This paper presents a new reducer-order observer for sensorless control of doubly fed induction generators (DFIGs), based on the Luenberger algorithm. Stable operation of the suggested observer is also considered in the design guidelines. Stator flux is selected as the state variable for the observer and its estimation error is used to correct the observer operation. The gain matrix of the proposed observer is calculated on the basis of flux error dynamics. The adaptation mechanism of the proposed observer is selected based on an estimation of rotor currents. A proportional integrator (PI) block is used in the structure of the …

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Robust Control For Line-Of-Sight Stabilization Of A Two-Axis Gimbal System, Mehmet Baskin, Mehmet Kemal Leblebi̇ci̇oğlu Jan 2017

Robust Control For Line-Of-Sight Stabilization Of A Two-Axis Gimbal System, Mehmet Baskin, Mehmet Kemal Leblebi̇ci̇oğlu

Turkish Journal of Electrical Engineering and Computer Sciences

Line-of-sight stabilization against various disturbances is an essential property of gimbaled imaging systems mounted on mobile platforms. In recent years, the importance of target detection from higher distances has increased. This has raised the need for better stabilization performance. For that reason, stabilization loops are designed such that they have higher gains and larger bandwidths. As these are required for good disturbance attenuation, sufficient loop stability is also needed. However, model uncertainties around structural resonances impose strict restrictions on sufficient loop stability. Therefore, to satisfy high stabilization performance in the presence of model uncertainties, robust control methods are required. In …

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Calculation Of Creepage Discharge Safety Factors Against The Tangential Component Of Electric Fields In The Insulation Structure Of Power Transformers, Arsalan Hekmati Jan 2017

Calculation Of Creepage Discharge Safety Factors Against The Tangential Component Of Electric Fields In The Insulation Structure Of Power Transformers, Arsalan Hekmati

Turkish Journal of Electrical Engineering and Computer Sciences

Creepage discharges are a main cause of insulation damage in power transformers during repeated tests or during operation. In this paper, a hazardous region in the insulation structure of power transformers (the interface between solid and liquid insulation at the top edge of a high-voltage electrode) is considered, and the impact of a very important factor of the surface discharge initiation and propagation (the tangential component of the electric field) on the strength of the insulation structure is investigated in power transformers. Insulation system reliability against this tangential component is presented as a safety factor. Two methods based on cumulative …

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Numerical Study Of Ac Loss Of Two-Layer Hts Power Transmission Cables Composed Of Coated Conductors With A Ferromagnetic Substrate, Şükrü Yildiz, Fedai̇ İnanir, Ahmet Çi̇çek, Fedor Gömöry Jan 2017

Numerical Study Of Ac Loss Of Two-Layer Hts Power Transmission Cables Composed Of Coated Conductors With A Ferromagnetic Substrate, Şükrü Yildiz, Fedai̇ İnanir, Ahmet Çi̇çek, Fedor Gömöry

Turkish Journal of Electrical Engineering and Computer Sciences

This work includes the simulation of hysteretic AC losses in two-layer HTS power transmission cables made of second-generation high-temperature superconducting tapes with a ferromagnetic substrate subject to an oscillating AC transport current, calling upon the COMSOL Multiphysics finite-element software program and exploiting an AC/DC module. How the AC transport loss is influenced by the arrangement of tapes, as well as the optimized design of superconducting power cables based on YBCO-coated conductors, are investigated. According to the radial arrangement of the tapes, four different orientations of ferromagnetic substrate are considered: 1) out-in (substrate of inner/outer layer facing outward/inward), 2) in-out (substrate …

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Lossless Predictive Coding Of Electric Signal Waveforms, Krzysztof Duda Jan 2017

Lossless Predictive Coding Of Electric Signal Waveforms, Krzysztof Duda

Turkish Journal of Electrical Engineering and Computer Sciences

This paper describes a new predictive coding algorithm designed for lossless compression of electric signal waveforms. Prediction coefficients are obtained from the sinusoidal signal autoregressive model. Predictors for a single sinusoid and the sum of two and three sinusoids are considered. Integer-to-integer coding is obtained by the proper (i.e. reversible) quantization of computations. The proposed coding algorithm shows better performance than the commonly used 2nd order differences coding and linear prediction coding that is optimal in the least squares sense.

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