A Generalized Algorithm For Space Vector Modulation In Multilevel Inverters,
2016
TÜBİTAK
A Generalized Algorithm For Space Vector Modulation In Multilevel Inverters, Erkan Meşe
Turkish Journal of Electrical Engineering and Computer Sciences
This paper proposes a new space vector pulse width modulation (SVPWM) algorithm for multilevel inverters that achieves a minimum number of switch state changes in one sampling cycle in order to reduce switching losses. The algorithm can be implemented with minimum computational burden and it does not require any look-up tables. The essence of the technique is to exploit the redundancy of switching functions in the implementation of the voltage vectors and dividing the entire vector space into three sectors in which switching functions have some common features. Careful observations showed that these common features lend themselves to be expressed …
Optimization Of An Experimental Unsymmetrical-Unbalanced Two-Phase Induction Motor Using The Hgapso Hybrid Technique And The Finite Element Method For Increasing Efficiency And Reducing Torque Ripple, Navid Horiyat, Seyed Mohammad Shariatmadar, Vahid Amir
Turkish Journal of Electrical Engineering and Computer Sciences
Two-phase induction motors make an important contribution to social welfare. Accordingly, enhanced quality in such motors would benefit society. This study was done to test this type of motor to determine a nonlinear optimal point in the form of a multiobjective function between ripple of the torque and motor efficiency with consideration of a weighted coefficient in an unbalanced-unsymmetrical two-phase induction motor. Tests demonstrated that minimizing total harmonic distortion could reduce torque ripple. The optimal point was determined using optimization algorithms, and a hybrid of genetic and particle swarm optimization algorithms simultaneously in order to increase efficiency and to reduce …
A Switching Inverse Dynamics Controller For Parallel Manipulators Around Drive Singular Configurations,
2016
TÜBİTAK
A Switching Inverse Dynamics Controller For Parallel Manipulators Around Drive Singular Configurations, Mustafa Özdemi̇r, Sitki Kemal İder
Turkish Journal of Electrical Engineering and Computer Sciences
Despite many advantages, parallel manipulators are known to possess drive singularities where the control of one or more degrees of freedom is lost. Around these singular configurations, the required actuator forces grow unbounded. Previous efforts in the literature put forward singularity-consistent trajectory planning and singularity-robust modification of the dynamic equations as a solution to this problem. However, this previous method is applicable only for the open-loop operation of the manipulator, whereas initial configuration errors, external disturbances, and modeling errors should necessarily be taken into account in a closed-loop sense in real-life applications. With this aim, a switching inverse dynamics controller …
Fast Image Search On A Vq Compressed Image Database,
2016
TÜBİTAK
Fast Image Search On A Vq Compressed Image Database, Mehmet Yakut
Turkish Journal of Electrical Engineering and Computer Sciences
A fast and efficient image search method is developed for a compressed image database using vector quantization (VQ). An image search on an image database requires an exhaustive sequential scan of all the images, given the similarity measure. If compressed images are dealt with, images are decompressed as an initial operation and then the previously mentioned exhaustive search is performed using the predetermined similarity measure. If the images in the database are compressed using VQ, the image search process is reduced to codebook index match tests. A pixel by pixel similarity test of two images computationally costs too much. This …
A New Compression Algorithm For Fast Text Search,
2016
TÜBİTAK
A New Compression Algorithm For Fast Text Search, Aydin Carus, Altan Mesut
Turkish Journal of Electrical Engineering and Computer Sciences
We propose a new compression algorithm that compresses plain texts by using a dictionary-based model and a compressed string-matching approach that can be used with the compressed texts produced by this algorithm. The compression algorithm (CAFTS) can reduce the size of the texts to approximately 41% of their original sizes. The presented compressed string matching approach (SoCAFTS), which can be used with any of the known pattern matching algorithms, is compared with a powerful compressed string matching algorithm (ETDC) and a compressed string-matching tool (Lzgrep). Although the search speed of ETDC is very good in short patterns, it can only …
Digital Implementation Of A Constant Frequency Hysteresis Controller For Dual Mode Operation Of An Inverter Acting As A Pv-Grid Interface And Statcom, Lenin Prakash, Arutchelvi Meenakshi Sundaram, Kalyanraj Durairaj
Turkish Journal of Electrical Engineering and Computer Sciences
This paper presents a new constant frequency hysteresis current controller for the grid interface of a PV-fed three-phase voltage source inverter (VSI) for a dual mode operation, feeding real power during the daytime and reactive power alone during nights, thereby acting as a STATCOM. The constant frequency is inherently achieved by means of digital implementation in a simplified manner without any complex manipulations to choose a variable band width; rather the hysteresis band varies as a natural consequence of selecting appropriate constant sampling frequency. Analytical proof is presented for the switching frequency to remain constant, without compromising on the performance …
Optimization Design Of A Doubly Salient 8/6 Srm Based On Three Computational Intelligence Methods,
2016
TÜBİTAK
Optimization Design Of A Doubly Salient 8/6 Srm Based On Three Computational Intelligence Methods, Fares Rebahi, Amar Bentounsi, Houssem Rafik El-Hana Bouchekara, Redjem Rebbah
Turkish Journal of Electrical Engineering and Computer Sciences
The aim of this paper is to optimize an 8/6 doubly salient switched reluctance machine using three computational intelligence methods, which include particle swarm optimization, a genetic algorithm, and differential evolution. Three cases are investigated where different parameters are considered like the stator pole arc, rotor pole arc, and ratios, which define the stator yoke and rotor thickness. The objective functions considered are the average torque and the torque-to-weight functions. The simulations are carried out using MATLAB and FEMM software. The optimal results found are compared with the initial design, and it is shown that high improvements are achieved.
A New Dictionary-Based Preprocessor That Uses Radix-190 Numbering,
2016
TÜBİTAK
A New Dictionary-Based Preprocessor That Uses Radix-190 Numbering, Mete Eray Şenergi̇n, Erhan Ali̇ri̇za İnce
Turkish Journal of Electrical Engineering and Computer Sciences
Various scholarly works in the literature have pointed out that placing a preprocessor in front of a standard postcompressor would help achieve higher gains while compressing natural-language text files. Ever since, there has been much research on preprocessors to improve the gain attained by concatenated systems. With the same goal in mind our paper proposes a new word-based preprocessor named METEHAN190 (M190) and contrasts its performance with four other state-of-the-art preprocessors. Throughout the experiments source files from the Wall Street Journal (WSJ) archive, and the Calgary, Canterbury, Gutenberg, and Pizza and Chili corpora were used. Postcompressors adapted were Prediction by …
Open Source Software Adoption Evaluation Through Feature Level Sentiment Analysis Using Twitter Data,
2016
TÜBİTAK
Open Source Software Adoption Evaluation Through Feature Level Sentiment Analysis Using Twitter Data, Muhammad Touseef Ikram, Naveed Anwer Butt, Muhammad Tanvir Afzal
Turkish Journal of Electrical Engineering and Computer Sciences
Adopting open source software from the Internet, developers often encounter the problem of accessing the quality of candidate software. To efficiently adopt the system they need a sort of quality guarantee regarding software resources. To assist the developer in software adoption evaluation we have proposed a software adoption assessment approach based on user comments. In our proposed approach, we first collected the textual reviews regarding the software resource, assigned the sentiment polarity (positive or negative) to each comment, extracted the adoption aspect which the comment talks about, and then based on the adoption aspects of the software generated an aggregated …
A 0.18-$\Mu $M Current-Mode Asynchronous Sigma-Delta Modulator Design,
2016
TÜBİTAK
A 0.18-$\Mu $M Current-Mode Asynchronous Sigma-Delta Modulator Design, Balkir Kayaalti, Ömer Ceri̇d, Günhan Dündar
Turkish Journal of Electrical Engineering and Computer Sciences
In this study a first-order asynchronous current-mode sigma-delta modulator has been designed and simulated. Asynchronous sigma-delta modulators eliminate the continuous time sigma-delta modulator's problem of signal-to-noise ratio degradation due to clock jitter by avoiding the use of sampling in the modulator loop. Moreover, they provide a higher signal-to-noise ratio even with low-order filters. Thus, considerably low power consumption can be achieved with fewer circuit components. The current mode enables designers to scale the circuits according to different supply voltages and operating currents. In this work, design steps for an asynchronous sigma-delta modulator have been given taking into account its ideal …
A Comprehensive Control Strategy Of Railway Power Quality Compensator For Ac Traction Power Supply Systems,
2016
TÜBİTAK
A Comprehensive Control Strategy Of Railway Power Quality Compensator For Ac Traction Power Supply Systems, Hamed Jafari Kaleybar, Siamak Farshad
Turkish Journal of Electrical Engineering and Computer Sciences
The development of electrical railway systems leads to critical power quality problems in the power grid. This paper discusses a kind of half-bridge-based railway power quality compensator system (HBRPQC) that can compensate negative sequence currents, harmonics, and reactive power simultaneously. In order to keep the HBRPQC performance efficient for the different kinds of transformers used in traction power supply substations, a new multifunctional control strategy that performs better than previous methods is proposed. Due to the fast dynamicity of traction loads, a recessive self-tuning PI controller based on fuzzy logic is adopted in the current control system. The output control …
Certain Investigations On Power Generation Using Repulsive Magnets And New Stepped Dc Coupled Quasi Z-Inverter,
2016
TÜBİTAK
Certain Investigations On Power Generation Using Repulsive Magnets And New Stepped Dc Coupled Quasi Z-Inverter, Meenakshi Thillainayagam, Suthanthira Vanitha Narayanan, Sujith Kumar Sivaraman
Turkish Journal of Electrical Engineering and Computer Sciences
This paper presents a novel approach for power generation from rotating machines in textile mills using externally coupled repulsive magnets and a new stepped DC coupled Quasi Z-inverter. Power is obtained as a byproduct of the effective harnessing of rotational energy with the use of repulsive magnets. This derived power is stored in a battery arrangement and is retrieved, buck/boosted, and converted to multilevel AC voltage with the new stepped DC coupled quasi Z-inverter. The proposed inverter is powered by isolated voltage sources, uses fewer switches, and produces less distortion in the resulting multilevel voltage compared to its counterpart, and …
Fpga Implementation Of A Hevc Deblocking Filter For Fast Processing Of Super High Resolution Applications,
2016
TÜBİTAK
Fpga Implementation Of A Hevc Deblocking Filter For Fast Processing Of Super High Resolution Applications, Awais Khan, Gulistan Raja
Turkish Journal of Electrical Engineering and Computer Sciences
This paper proposes the architecture of a deblocking filter (DBF) that removes blocking artifacts in new emerging High Efficiency Video Coding (HEVC). A parallel architecture for both normal and strong filtering modes of HEVC is proposed. Distributed memories and two data paths increase the parallelism and make the architecture more efficient. The proposed architecture is described by Verilog and implemented on FPGA. The architecture can realize real time to compute 4K UHD video at 30 fps by using 46.65 million clocks with total equivalent gate count of 46K. The maximum delay time for output to come after taking input for …
An Interval-Based Contingency Selection Approach Considering Uncertainty,
2016
TÜBİTAK
An Interval-Based Contingency Selection Approach Considering Uncertainty, Chao Xu, Wei Gu, Lizi Luo, Jianguo Yao, Shengchun Yang, Ke Wang, Dan Zeng, Miao Fan
Turkish Journal of Electrical Engineering and Computer Sciences
Static security assessment is affected by uncertainties of load flow distributions introduced by renewable sources. A fast contingency selection approach based on interval theory is proposed in this paper. Firstly, an interval line active flow calculation algorithm is developed to reduce conservation in application of interval mathematics in line flow calculation. Then a novel interval comparison method based on Bayesian probability theory is applied in interval index comparison to give the relative severity information of contingencies. Finally, an approximately consistent ranking method is utilized in contingency ranking to rank screened contingencies. Numerical studies on several IEEE standard test systems and …
A Comparative Analysis Of Wind Speed Probability Distributions For Wind Power Assessment Of Four Sites,
2016
TÜBİTAK
A Comparative Analysis Of Wind Speed Probability Distributions For Wind Power Assessment Of Four Sites, Vaishali Sohoni, Shivcharan Gupta, Rajeshkumar Nema
Turkish Journal of Electrical Engineering and Computer Sciences
In this paper, five probability distribution functions are employed to fit the wind speed data from four different geographical locations in the world in a preliminary analysis. These wind regimes are selected such that they represent wide ranges of mean wind speeds and present different shapes of wind speed histograms. The wind speed data used for modelling consist of 10-min average SCADA data from three US wind farms and hourly averages recorded at a weather station in Canada. Out of the five, three functions, namely Weibull, Rayleigh, and gamma, which provide a better fit to the data, are selected to …
Integration Of Spectral And Spatial Information Via Local Covariance Matrices For Segmentation And Classification Of Hyperspectral Images, Uğur Ergül, Gökhan Bi̇lgi̇n
Turkish Journal of Electrical Engineering and Computer Sciences
In this work, a novel approach is presented for the feature extraction step in hyperspectral image processing to form more discriminative features between different pixel regions. The proposed method combines both spatial and spectral information, which is very important for segmentation and classification of hyperspectral images. For comparison, five different feature sets are formed using eigen decomposition of local covariance matrices of subcubes located around a pixel of interest in the scene. Subcubes of neighbor pixels are obtained by a windowed structure to expose pattern similarities. As a novel approach, local covariance matrices are computed in eigenspace and proposed feature …
Solar Irradiation Estimator Based On A Self-Calibrated Reference Solar Cell,
2016
TÜBİTAK
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 …
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 …
Design And Implementation Of A Genetic Algorithm Ip Core On An Fpga For Path Planning Of Mobile Robots,
2016
TÜBİTAK
Design And Implementation Of A Genetic Algorithm Ip Core On An Fpga For Path Planning Of Mobile Robots, Adem Tuncer, Mehmet Yildirim
Turkish Journal of Electrical Engineering and Computer Sciences
This paper presents a hardware realization of a genetic algorithm (GA) for the path planning problem of mobile robots on a field programmable gate array (FPGA). A customized GA intellectual property (IP) core was designed and implemented on an FPGA. A Xilinx xupv5-lx110t FPGA device was used as the hardware platform. The proposed GA IP core was applied to a Pioneer 3-DX mobile robot to confirm its path planning performance. For localization tasks, a camera mounted on the ceiling of the laboratory was utilized to receive images and allow the robot to determine its own location and the obstacles in …
A Fast And Accurate Algorithm For Eye Opening Or Closing Detection Based On Local Maximum Vertical Derivative Pattern,
2016
TÜBİTAK
A Fast And Accurate Algorithm For Eye Opening Or Closing Detection Based On Local Maximum Vertical Derivative Pattern, Marzieh Tafreshi, Ali Mohammad Fotouhi
Turkish Journal of Electrical Engineering and Computer Sciences
In this paper, a fast and accurate algorithm is proposed to recognize open and closed eye states. In the proposed algorithm, first a hierarchical preprocessing stage is used to detect eye areas. This stage employs Haar features to detect face area, color, and intensity mappings to extract eye candidate areas, and some simple geometrical relations for a final decision of the eye regions. In the second stage of the algorithm for detecting eye state, a new proposed descriptor based on a histogram of local maximum vertical derivative patterns in eye areas is extracted and applied to a support vector machine …
