The Phononic Crystal Interface Layer Determines Slow-Wave And Pulse Broadening Effects,
2016
TÜBİTAK
The Phononic Crystal Interface Layer Determines Slow-Wave And Pulse Broadening Effects, Li Sun, Aiming Ji, Jialing Hu, Canyan Zhu, Lijun Zhang, Jianfeng Yang, Lingfeng Mao
Turkish Journal of Electrical Engineering and Computer Sciences
The relationship among the slow-wave and echo pulse broadening effects in reflected acoustic waves and the width of the interface layer of phononic crystal has been theoretically investigated. It has been observed that not only the slow time for the reflected acoustic wave but also the echo pulse broadening reaches a saturation point as the size of the phononic crystal increases. From the viewpoint of the acoustic wave, there is an interface layer in the crystal that determines the slow-wave and the echo pulse broadening effects. The longest slow time, which is the time needed for transmitting 0.08 periods of …
A Hybrid Search Method Of Wrapper Feature Selection By Chaos Particle Swarm Optimization And Local Search,
2016
TÜBİTAK
A Hybrid Search Method Of Wrapper Feature Selection By Chaos Particle Swarm Optimization And Local Search, Mohammad Masoud Javidi, Nasibeh Emami
Turkish Journal of Electrical Engineering and Computer Sciences
Finding a subset of features from a large dataset is a problem that arises in many fields of study. Since the increasing number of features has extended the computational cost of a system, it is necessary to design and implement a system with the least number of features. The purpose of feature selection is to find the best subset of features from the original ones. The result of the best selection is improving the computational cost and the accuracy of the prediction. A large number of algorithms have been proposed for feature subset selection. In this paper, we propose a …
A Ring Crossover Genetic Algorithm For The Unit Commitment Problem,
2016
TÜBİTAK
A Ring Crossover Genetic Algorithm For The Unit Commitment Problem, Syed Basit Ali Bukhari, Aftab Ahmad, Syed Auon Raza, Muhammad Noman Siddique
Turkish Journal of Electrical Engineering and Computer Sciences
The unit commitment problem (UCP) is a nonlinear, mixed-integer, constraint optimization problem and is considered a complex problem in electrical power systems. It is the combination of two interlinked subproblems, namely the generator scheduling problem and the generation allocation problem. In large systems, the UCP turns out to be increasingly complicated due to the large number of possible ON and OFF combinations of units in the power system over a scheduling time horizon. Due to the insufficiency of conventional approaches in handling large systems, numerous metaheuristic techniques are being developed for solving this problem. The genetic algorithm (GA) is one …
Electric Arc Furnace Power Quality Improvement By Applying A New Digital And Predicted-Based Tsc Control,
2016
TÜBİTAK
Electric Arc Furnace Power Quality Improvement By Applying A New Digital And Predicted-Based Tsc Control, Mehdi Torabian Esfahani, Behrooz Vahidi
Turkish Journal of Electrical Engineering and Computer Sciences
Static VAR compensators (SVC) can improve some of the power quality (PQ) indices such as voltage flicker, unbalances, and power factors in power systems if properly controlled. Different nonlinear and time-varying loads generate these parameters. One of the great nonlinear loads is the electric arc furnace (EAF), which causes waveform distortions, voltage unbalances, and fluctuations. In this paper, a new digital and prediction-based control for thyristor switched capacitors (TSCs) was proposed to compensate an actual steel industrial plant. The digital control was based on generating adequate synchronous pulses, calculating required suitable susceptance, and measuring correct reactive power. The proposed TSC …
Fuzzy Speed Estimation In The Case Of Sensorless Induction Machine Vector Control,
2016
TÜBİTAK
Fuzzy Speed Estimation In The Case Of Sensorless Induction Machine Vector Control, Mohamed Bahloul, Mansour Souissi, Mohamed Chaabane, Larbi Chrifi Alaoui, Said Drid
Turkish Journal of Electrical Engineering and Computer Sciences
This paper deals with the problem of sensorless indirect field oriented control of an induction machine. Based on the fourth-order nonlinear model, we propose a novel structure of a full-order Takagi-Sugeno (TS) adaptive observer, through which we ensure the estimation of IM states and the rotor speed, which is considered as an immeasurable premise variable. This approach satisfies global stability for all operating conditions and operates under unknown applied load torque. In this work, a TS fuzzy model is presented to approximate a nonlinear IM model in the stationary rotating reference frame. A TS adaptive observer is then described. We …
Using Magnetic Field Analysis To Evaluate The Suitability Of A Magnetic Suspension System For Lightweight Vehicles,
2016
TÜBİTAK
Using Magnetic Field Analysis To Evaluate The Suitability Of A Magnetic Suspension System For Lightweight Vehicles, Hazril Md Isa, Noor Hafizah Amer, Wan Nor Liza Wan Mahadi, Rahizar Ramli
Turkish Journal of Electrical Engineering and Computer Sciences
A suspension system in a vehicle acts as an isolator that isolates vibrations between the wheel tires and the vehicle body due to road irregularities. Additionally, a suspension system serves as a vehicle stabilizer that stabilizes the vehicle body during unusual driving patterns such as cornering, braking, or accelerating. A controllable suspension system has received significant attention in the automotive world in previous years since it can perform both of the aforementioned tasks without the presence of fluid damper. The study presented in this paper focuses on using magnetic flux density analysis to evaluate a number of parameters of an …
Energy-Aware Stochastic Scheduling Model With Precedence Constraints On Dvfs-Enabled Processors,
2016
TÜBİTAK
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 …
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 …
Exploring Feature Sets For Turkish Word Sense Disambiguation,
2016
TÜBİTAK
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), …
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 …
The Simulation Of Sound Signal Masking With Different Chaotic Oscillations And Its Circuit Application,
2016
TÜBİTAK
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 …
Improving Response Time Of Database Systems By Semantification Of Relational Data,
2016
TÜBİTAK
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 …
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 …
Computer-Assisted Cobb Angle Measurement From Posteroanterior Radiographs By A Curve Fitting Method,
2016
TÜBİTAK
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 …
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 …
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 …
Validation Of Trnsys Modelling For A Fixed Slope Photovoltaic Panel,
2016
TÜBİTAK
Validation Of Trnsys Modelling For A Fixed Slope Photovoltaic Panel, Kant Kanyarusoke, Jasson Gryzagoridis, Graeme Oliver
Turkish Journal of Electrical Engineering and Computer Sciences
TRNSYS stands for transient system simulation software. This paper describes a procedure that was used to validate a TRNSYS model for estimating electricity yields from a fixed slope photovoltaic (PV) panel. The objective was to find how close to reality predicted energy yield for a specified panel can be, at a location near one of the weather stations listed in the software's database. The software was used to predict daily total incident radiation on a horizontal plane and electrical energy yields from a 90 Wp panel when sloped at 34$^{\circ}$ facing north at a test site in Cape Town, South …
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 …
Assessment Of Energy Performance Certificate Systems: A Case Study For Residential Buildings In Turkey,
2016
TÜBİTAK
Assessment Of Energy Performance Certificate Systems: A Case Study For Residential Buildings In Turkey, Kenan Yi̇ği̇t, Bora Acarkan
Turkish Journal of Electrical Engineering and Computer Sciences
The importance of sustainable development and energy efficiency efforts has increased in the construction sector. Energy-saving efforts for buildings have become more important due to the global energy crisis, and energy rating systems have been developed globally for assessment of energy performance. In this study, international green building certificate and energy performance certificate (EPC) systems are presented. The official EPC system for buildings in Turkey is illustrated with case studies. Energy consumption and greenhouse gas emissions from residential buildings are calculated using the official national software, which is called BEP-TR. The impact of lighting on the total energy performance of …
Effect Of Transverse Magnetic Field On Low Pressure Argon Discharge,
2016
TÜBİTAK
Effect Of Transverse Magnetic Field On Low Pressure Argon Discharge, Ehsan Hashemi, Kaveh Niayesh, Hossein Mohseni
Turkish Journal of Electrical Engineering and Computer Sciences
A numerical simulation was performed to investigate the effect of transverse magnetic fields on low pressure argon plasma. Discovering the variations in electric field, electric potential, power consumption in plasma, and dominant physical mechanisms after application of magnetic fields is the main output of this analysis. A simulation was performed using the finite element method. A 2-fluid model equipped with chemical reaction equations in argon plasma, heat transfer equation, and Poisson's equation was used to describe the plasma behavior. Two disk-shaped electrodes separated by 12 mm from each other were considered as a plasma chamber and an external transverse magnetic …
