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2016

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Articles 1201 - 1230 of 1427

Full-Text Articles in Computer Engineering

Energy-Aware Stochastic Scheduling Model With Precedence Constraints On Dvfs-Enabled Processors, Mohammad Sajid, Zahid Raza Jan 2016

Energy-Aware Stochastic Scheduling Model With Precedence Constraints On Dvfs-Enabled Processors, Mohammad Sajid, Zahid Raza

Turkish Journal of Electrical Engineering and Computer Sciences

The stochastic scheduling of precedence-constrained jobs on a heterogeneous processor is a challenging problem that requires solutions with one or more optimized QoS parameters. In this work, an energy-aware stochastic algorithm is proposed to schedule the batch of precedence-constrained jobs on heterogeneous DVFS-enabled processors with the objective of optimizing turnaround time and energy consumption. The processing time of tasks in all jobs and their precedence-constraint times are governed by independent probability distributions. The performance of the proposed stochastic algorithm is compared with SHEFT and ECS based on randomly generated batches of different sizes. The experimental study reveals that the proposed …

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Performance Comparison Of Adaptive Digital Predistortion Algorithms Using Adaptation Time For Mobile Wimax Power Amplifier Applications, Ji-Yeon Kim, Jong-Heon Kim Jan 2016

Performance Comparison Of Adaptive Digital Predistortion Algorithms Using Adaptation Time For Mobile Wimax Power Amplifier Applications, Ji-Yeon Kim, Jong-Heon Kim

Turkish Journal of Electrical Engineering and Computer Sciences

In this paper, we propose that adaptation time be considered a parameter for evaluating the performance of digital filter algorithms in adaptive digital predistorted high-power amplifiers. An adaptive predistorted high-power amplifier with an average power of 37.5 dBm was designed and fabricated for mobile worldwide interoperability for microwave access (WiMAX) test signals. For performance comparisons using adaptation time, several effective algorithms (such as the least-mean-squares (LMS), recursive-least-squares (RLS), and affine projection (AP) algorithms) were implemented. According to the experimental results, the RLS and AP algorithms achieved a similar linearity improvement of 11 dBr. However, the AP algorithm had the advantage …

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Selective Harmonics Elimination Pwm With Self-Balancing Dc-Link In Photovoltaic 7-Level Inverter, Khoukha Imarazene, Hachemi Chekireb, El Madjid Berkouk Jan 2016

Selective Harmonics Elimination Pwm With Self-Balancing Dc-Link In Photovoltaic 7-Level Inverter, Khoukha Imarazene, Hachemi Chekireb, El Madjid Berkouk

Turkish Journal of Electrical Engineering and Computer Sciences

In this paper, a new DC-link balancing method for a 7-level inverter fed by a photovoltaic system is proposed. The proposed redundant state technique is associated with selective harmonics elimination (SHE)-PWM instead of space vector (SV)-PWM. The switching angles related to the SHE are computed via the resultant theory method. Moreover, the study of this inverter is carried out on its equivalent matrix model. On the basis of this model, the link between the capacitor voltage, switching states, and load current is established. This allows understanding the switching redundancies' effect on the DC capacitor voltage balance. An algorithm is then …

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Assessment Of The Maximum Loadability Point Of A Power System After Third Zone Of Distance Relay Corrective Actions, Zahra Moravej, Sajad Bagheri Jan 2016

Assessment Of The Maximum Loadability Point Of A Power System After Third Zone Of Distance Relay Corrective Actions, Zahra Moravej, Sajad Bagheri

Turkish Journal of Electrical Engineering and Computer Sciences

In this paper, the operation of a system and distance relay is improved during voltage instability by using an improved strategy. After detecting the voltage instability, the third zone is blocked. However, the system is prone to voltage collapse. Shunt capacitor compensation and a load shedding scheme can be used to protect the system from voltage collapse conditions. Load shedding plans can be performed based on a reduction in the power flow in the line where the relay is located. The reason is that the minimum eigenvalue of the load flow Jacobian (reduced and unreduced Jacobians) is increased and the …

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Evaluation Of Hearing Loss Simulation Using A Speech Intelligibility Index, Umut Ariöz, Banu Günel Jan 2016

Evaluation Of Hearing Loss Simulation Using A Speech Intelligibility Index, Umut Ariöz, Banu Günel

Turkish Journal of Electrical Engineering and Computer Sciences

Hearing loss simulation (HLS) is a useful tool for hearing studies, since finding large numbers of hearing-impaired volunteers with various levels of hearing loss is usually a problem. Correct simulation of the hearing impaired ear should take into account different suprathreshold effects, such as reduced frequency selectivity, reduced audibility, and loudness recruitment. Although these effects can be implemented using various algorithms, so far they have not been evaluated in detail taking into account subject dependency, effect of noisy environment, and phonetic characteristics of test words. In this study, for the purpose of evaluating the HLS, a speech intelligibility index (SII) …

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An Ipr Protection Scheme Based On Wavelet Transformation And Visual Cryptography, Young Chang Hou, A-Yu Tseng, Zen-Yu Quan, Hsin-Ju Liu Jan 2016

An Ipr Protection Scheme Based On Wavelet Transformation And Visual Cryptography, Young Chang Hou, A-Yu Tseng, Zen-Yu Quan, Hsin-Ju Liu

Turkish Journal of Electrical Engineering and Computer Sciences

As information technology is fast developing, it brings great convenience to our everyday life. However, hackers may also access confidential data illegally and easily from computers over the Internet. Therefore, how to protect property rights against infringement is an essential issue. Digital watermarking is a method that adds personal information to an intellectual property to protect one's ownership rights. Should the intellectual property be disputed, the owner can retrieve the watermark and prove ownership rights. Based on the principles of visual cryptography and the law of large numbers, our study generates shares by comparing pseudorandomly selected value pairs during the …

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High Photoresponse From Solution Processed Conventional And Inverted Ultraviolet Photodetectors, Görkem Memi̇şoğlu, Canan Varlikli Jan 2016

High Photoresponse From Solution Processed Conventional And Inverted Ultraviolet Photodetectors, Görkem Memi̇şoğlu, Canan Varlikli

Turkish Journal of Electrical Engineering and Computer Sciences

The optical and electrical properties of conventional and inverted type ultraviolet photodetectors (UVPDs) with active layers of poly(9,9-dioctylfluorenyl-2,7-ylenethynylene (PFE), $N$,$N'$-bis-$n$-butyl-1,4,5,8-naphthalenediimide (BNDI), and zincoxide (ZnO) are introduced. Optimized devices showed high photoresponse, external quantum efficiency (EQE), and detectivity (D*) values. Under 365 nm 1 mW/cm$^{2}$, the conventional device (ITO/PEDOT:PSS/[(PFE:BNDI) (3:1):8 wt% ZnO]/Al) and the inverted device (ITO/[(PFE:BNDI)(3:1):8 wt% ZnO]/Au) gave photoresponsivities of 515 mA/W and 316 mA/W, D* of 1.12 $\times$ 10$^{14 }$Jones and 0.71 $\times$ 10$^{14 }$Jones, and EQE of 174% and 107%, respectively. Annealing the devices at polymer's glass transition temperature (T$_{g}$ 60 $^{\circ}$ C), enhanced these values to …

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Stability Assessment Of Isolated Six-Phase Induction Generator Feeding Static Loads, Kiran Singh, Girish Kumar Singh Jan 2016

Stability Assessment Of Isolated Six-Phase Induction Generator Feeding Static Loads, Kiran Singh, Girish Kumar Singh

Turkish Journal of Electrical Engineering and Computer Sciences

This paper presents the stability analysis of a six-phase self-excited induction generator (SP-SEIG) based on the eigenvalue stability criteria for its linearized model. This demonstrates the small signal stability behavior during steady-state operating conditions. The eigenvalue approach also establishes an opportunity to correlate eigenvalues with machine parameters. The investigation in this paper reveals that the eigenvalues are dependent upon the machine parameters, and the most critical parameter is the variation in magnetizing inductance (L$_{m})$. The eigenvalues are varied in accordance with the machine variables and give focus to the stabilization of the SP-SEIG. A particular voltage build-up phenomenon is also …

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A Novel Voltage Control Strategy In Collaboration With Information Technology Domains Through The Holonic Architecture, Javad Ansari, Mehdi Ghazavi Dozein, Ahad Kazemi Jan 2016

A Novel Voltage Control Strategy In Collaboration With Information Technology Domains Through The Holonic Architecture, Javad Ansari, Mehdi Ghazavi Dozein, Ahad Kazemi

Turkish Journal of Electrical Engineering and Computer Sciences

This paper presents a novel framework for voltage control based on holonic architecture, with a priority action of local controllers. The proposed architecture is a hierarchical distributed structure in which two various information technology domains called the energy management system holon and flexible AC transmission system holon are defined. In the proposed structure, a dynamic reconfiguring method for holons is used to reduce the time of corrective actions in the case of emergencies.

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A Switching Inverse Dynamics Controller For Parallel Manipulators Around Drive Singular Configurations, Mustafa Özdemi̇r, Sitki Kemal İder Jan 2016

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 …

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Keyframe-Based Video Mosaicing For Historical Ottoman Documents, Edi̇z Şaykol Jan 2016

Keyframe-Based Video Mosaicing For Historical Ottoman Documents, Edi̇z Şaykol

Turkish Journal of Electrical Engineering and Computer Sciences

Image mosaicing is a trendy research area in computer vision in recent years. Instead of images, video frames can be mosaiced to form a larger aggregate. In both cases, merging computations generally depend on the common parts in consecutive images, which are called overlapping regions. The presence of mobile devices with a camera provides higher image and video acquisition; hence video mosaicing techniques can be utilized to digitize and to create high resolution historical document images for later use in browsing and retrieval systems. Here, we present a technique to create high resolution images of historical Ottoman documents from video. …

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Time Series Adapted Supervised Fuzzy Discretization: An Application To Ecg Signals, Umut Orhan Jan 2016

Time Series Adapted Supervised Fuzzy Discretization: An Application To Ecg Signals, Umut Orhan

Turkish Journal of Electrical Engineering and Computer Sciences

In this study, a new method called supervised fuzzy discretization (SFD), which can be used without having expertise on data, is proposed for classifying time series datasets. Because an ECG signal has a partially stationary characteristic, its classification process is more difficult than it would be for completely stationary signals. On the other hand, because the method proposed can be used without having expertise on the data, comprehensive data like ECG signals are enough to introduce one such method. To prove the efficacy of the SFD, RR intervals selected from a common ECG database are used in the classification experiments. …

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Fast Image Search On A Vq Compressed Image Database, Mehmet Yakut Jan 2016

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 …

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A New Step-Size Searching Algorithm Based On Fuzzy Logic And Neural Networks For Lms Adaptive Beamforming Systems, Walter Orozco-Tupacyupanqui, Mariko Nakano-Miyatake, Hector Perez Meana Jan 2016

A New Step-Size Searching Algorithm Based On Fuzzy Logic And Neural Networks For Lms Adaptive Beamforming Systems, Walter Orozco-Tupacyupanqui, Mariko Nakano-Miyatake, Hector Perez Meana

Turkish Journal of Electrical Engineering and Computer Sciences

In this paper, a novel algorithm based on fuzzy logic and neural networks is proposed to find an approximation of the optimal step size $\mu $ for least-mean-squares (LMS) adaptive beamforming systems. A new error ensemble learning (EEL) curve is generated based on the final prediction value of the ensemble-average learning curve of the LMS adaptive algorithm. This information is classified and fed into a back propagation neural network, which automatically generates membership functions for a fuzzy inference system. An estimate of the optimal step size is obtained using a group of linguistic rules and the corresponding defuzzification method. Computer …

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Exploring Feature Sets For Turkish Word Sense Disambiguation, Bahar İlgen, Eşref Adali, Ahmet Cüneyd Tantuğ Jan 2016

Exploring Feature Sets For Turkish Word Sense Disambiguation, Bahar İlgen, Eşref Adali, Ahmet Cüneyd Tantuğ

Turkish Journal of Electrical Engineering and Computer Sciences

This paper presents an exploration and evaluation of a diverse set of features that influence word-sense disambiguation (WSD) performance. WSD has the potential to improve many natural language processing (NLP) tasks as being one of the most crucial steps in the area. It is known that exploiting effective features and removing redundant ones help improving the results. There are two groups of feature sets to disambiguate senses and select the most appropriate ones among a set of candidates: collocational and bag-of-words (BoW) features. We introduce the effects of using these two feature sets on the Turkish Lexical Sample Dataset (TLSD), …

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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 Jan 2016

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 …

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The Simulation Of Sound Signal Masking With Different Chaotic Oscillations And Its Circuit Application, Mehmet Nuri̇ Almali, Zi̇nnur Di̇ki̇ci̇ Jan 2016

The Simulation Of Sound Signal Masking With Different Chaotic Oscillations And Its Circuit Application, Mehmet Nuri̇ Almali, Zi̇nnur Di̇ki̇ci̇

Turkish Journal of Electrical Engineering and Computer Sciences

The chaotic masking process on sound signals using the systems of Lorenz, Rössler, Sprott, Chen, and Arneodo chaotic oscillations are simulated with MATLAB/Simulink. The PID control method providing synchronization in the system is defined and the mean square errors between the times to reach synchronization and the input-output sound signals are compared for the system performance. The Sprott chaotic system is found to be the best synchronized system. Therefore, the application circuits are designed with respect to the Sprott chaotic system and its results are investigated in this study. It is seen that the system marked with the Sprott chaotic …

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An Attribute Or Tuple Timestamping In Bitemporal Relational Databases, Canan Atay Jan 2016

An Attribute Or Tuple Timestamping In Bitemporal Relational Databases, Canan Atay

Turkish Journal of Electrical Engineering and Computer Sciences

Much of the research on bitemporal databases has focused on the modeling of time-related data with either attribute or tuple timestamping. While the attribute-timestamping approach attaches bitemporal data to attributes, the tuple-timestamping approach splits the object's history into several tuples. Although there have been numerous studies on bitemporal data models, there is no work contrasting these two common approaches in terms of system performance and ease of use. In this paper, we compared interval-based attribute- and tuple-timestamped bitemporal data models by running sample queries to measure processing time, and then we evaluated their usability by using the same data. Our …

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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 Jan 2016

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.

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The Impact Of Disabling Suspicious Node Communications On Network Lifetime In Wireless Ad Hoc Sensor Networks, Zeydi̇n Pala, Ni̇hat İnanç Jan 2016

The Impact Of Disabling Suspicious Node Communications On Network Lifetime In Wireless Ad Hoc Sensor Networks, Zeydi̇n Pala, Ni̇hat İnanç

Turkish Journal of Electrical Engineering and Computer Sciences

In wireless sensor networks (WSNs), the data observed by different nodes must be relayed safely to the base station over intermediate nodes. In the network environment, some sensor nodes can act suspiciously when they enter someone else's control or due to other equipment failure. Data packets that are sent through suspicious nodes may be randomly dropped or may be not delivered as desired. In this paper, we investigate the impact of disabling suspicious nodes communications on network lifetime through a linear programming framework. We build a mathematical programming framework and perform comprehensive numerical analysis. Our results show that the decrease …

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Hardware Implementation Of A Scale And Rotation Invariant Object Detection Algorithm On Fpga For Real-Time Applications, Murat Peker, Hali̇s Altun, Fuat Karakaya Jan 2016

Hardware Implementation Of A Scale And Rotation Invariant Object Detection Algorithm On Fpga For Real-Time Applications, Murat Peker, Hali̇s Altun, Fuat Karakaya

Turkish Journal of Electrical Engineering and Computer Sciences

A hardware implementation of a computationally light, scale, and rotation invariant method for shape detection on FPGA is devised. The method is based on histogram of oriented gradients (HOG) and average magnitude difference function (AMDF). AMDF is used as a decision module that measures the similarity/dissimilarity between HOG vectors of an image in order to classify the object. In addition, a simulation environment implemented on MATLAB is developed in order to overcome the time-consuming and tedious process of hardware verification on the FPGA platform. The simulation environment provides specific tools to quickly implement the proposed methods. It is shown that …

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Optimal Placing Of Pmus In A Constrained Grid: An Approach, Jyoti Bhonsle, Anjali Junghare Jan 2016

Optimal Placing Of Pmus In A Constrained Grid: An Approach, Jyoti Bhonsle, Anjali Junghare

Turkish Journal of Electrical Engineering and Computer Sciences

Synchronized phasor measurement units (PMUs) are replacing conventional measuring meters in modern power networks. The paradigm of grid monitoring has shifted to a wider area. This offers better monitoring, protection, and control of the overall power grid. This paper presents an approach for optimal placing of PMUs in constrained power grids using the binary integer programming technique. The proposed approach deals with four constraints: 1) observability of network, two cases of fully observable and partially observable networks are investigated; 2) conventional measurements, three cases of zero injection bus and injection measurement, conventional power flow measurement, and both injection and power …

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A New Cmos Logarithmic Current Generator, Munir Al Absi, Karama Al Tamimi Jan 2016

A New Cmos Logarithmic Current Generator, Munir Al Absi, Karama Al Tamimi

Turkish Journal of Electrical Engineering and Computer Sciences

A new CMOS current-mode controllable low-voltage and low-power logarithmic function circuit is proposed. The circuit provides good dynamic range, controllable output, and reasonable accuracy and it is insensitive to temperature variations. The circuit operates with $\pm $0.5 V supply, consumes 0.3 $\mu $W, and has a -3 dB frequency of 2.4 MHz. The functionality of the proposed design is confirmed using Tanner T-spice with 0.35 $\mu $m CMOS process.

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Novel Version Of Bi Input-Extended Kalman Filter For Speed-Sensorless Control Of Induction Motors With Estimations Of Rotor And Stator Resistances, Load Torque, And Inertia, Emrah Zerdali̇, Murat Barut Jan 2016

Novel Version Of Bi Input-Extended Kalman Filter For Speed-Sensorless Control Of Induction Motors With Estimations Of Rotor And Stator Resistances, Load Torque, And Inertia, Emrah Zerdali̇, Murat Barut

Turkish Journal of Electrical Engineering and Computer Sciences

This study aims to develop a novel version of bi input-extended Kalman filter (BI-EKF)-based estimation technique in order to increase the number of state and parameter estimations required for speed-sensorless direct vector control (DVC) systems, which perform velocity and position controls of induction motors (IMs). For this purpose, all states required for the speed-sensorless DVC systems, besides the stator resistance $R_{s} $, the rotor resistance $R_{r}$, the load torque $t_{L}$ including the viscous friction term, and the reciprocal of total inertia $1/j_{T}$, are simultaneously estimated by the novel BI-EKF algorithm using the measured phase currents and voltages. The effectiveness of …

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A Monte Carlo-Based Poisson's Equation Solver Parallelized With Coarray Fortran, Nevsan Şengi̇l, Özgür Tümüklü, Mehmet Cevdet Çelenli̇gi̇l Jan 2016

A Monte Carlo-Based Poisson's Equation Solver Parallelized With Coarray Fortran, Nevsan Şengi̇l, Özgür Tümüklü, Mehmet Cevdet Çelenli̇gi̇l

Turkish Journal of Electrical Engineering and Computer Sciences

Poisson's equation is found in many scientific problems, such as heat transfer and electric field calculations. Although many different techniques are involved in solving Poisson's equation, we focused on the Monte Carlo method (MCM). We preferred the MCM not only because of its simple algorithm but also for its excellent parallel efficiency. Parallelization is one of the most effective techniques for reducing computation time. Among many parallelization paradigms, such as OpenMP (open multiprocessing), MPI (message passing interface), and PGAS (partitioned global address space), we adopted the PGAS-based Coarray Fortran (CAF). In this paper, we demonstrated that parallelization of Poisson's equation …

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Improving Response Time Of Database Systems By Semantification Of Relational Data, Mustafa Yeni̇ad, Yakup Kutlu Jan 2016

Improving Response Time Of Database Systems By Semantification Of Relational Data, Mustafa Yeni̇ad, Yakup Kutlu

Turkish Journal of Electrical Engineering and Computer Sciences

New generation web technologies present the new problem of intelligent representation of data in semantically structured systems. In this study, data hosted in a relational database system were converted to a new generation of web technologies (i.e. Web 3.0) with the semantic mapping method and semantification of the data was accomplished. The success of the transformation procedure was verified by a cross-comparison of the data between the relational database and the semantic data repository. By comparing the response time for performing SQL queries and equivalent SPARQL queries such as select, insert, update, and delete, operations hold in the semantic data …

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A 0.18-$\Mu $M Current-Mode Asynchronous Sigma-Delta Modulator Design, Balkir Kayaalti, Ömer Ceri̇d, Günhan Dündar Jan 2016

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 …

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A Comprehensive Control Strategy Of Railway Power Quality Compensator For Ac Traction Power Supply Systems, Hamed Jafari Kaleybar, Siamak Farshad Jan 2016

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 …

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Computer-Assisted Cobb Angle Measurement From Posteroanterior Radiographs By A Curve Fitting Method, İbrahi̇m Yildiz Jan 2016

Computer-Assisted Cobb Angle Measurement From Posteroanterior Radiographs By A Curve Fitting Method, İbrahi̇m Yildiz

Turkish Journal of Electrical Engineering and Computer Sciences

Incorrect determination of the top or end vertebrae of a scoliotic curve causes measurement errors when using the Cobb method. Such problems are due to subjectivity. This study was performed to minimize subjectivity by using a curve fitting method. A digitally scanned posteroanterior radiographic image was used for each patient. User-defined midpoints of the curvature, which indicate the midpoints of the vertebrae, were used to fit the polynomial equation. The locations of the top and end vertebrae were calculated using the first derivative of the fitted polynomial equation to obtain the analytical Cobb angle. The interobserver technical error of measurements …

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The Self-Adaptive Alternating Direction Method For The Multiarea Economic Dispatch Problem, Yaming Ren, Shumin Fei, Haikun Wei Jan 2016

The Self-Adaptive Alternating Direction Method For The Multiarea Economic Dispatch Problem, Yaming Ren, Shumin Fei, Haikun Wei

Turkish Journal of Electrical Engineering and Computer Sciences

The alternating direction method has been used widely in the power systems field for solving the multiarea dispatch problem. However, experience with applications has shown that the convergence rate of the alternating direction method depends significantly on the selection of the penalty parameter of the linear consistency constraint. Typically, it is difficult to obtain the optimal penalty parameter in advance. In this paper, for the purpose of solving this problem, we propose centralized and distributed self-adaptive penalty parameter strategies that allow the value of the penalty parameter to increase or decrease based on the information from each iteration. Simulation results …

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