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Articles 31 - 60 of 372
Full-Text Articles in Engineering
The Impact Of Disabling Suspicious Node Communications On Network Lifetime In Wireless Ad Hoc Sensor Networks, Zeydi̇n Pala, Ni̇hat İnanç
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 …
Open Source Software Adoption Evaluation Through Feature Level Sentiment Analysis Using Twitter Data, Muhammad Touseef Ikram, Naveed Anwer Butt, Muhammad Tanvir Afzal
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 $M Current-Mode Asynchronous Sigma-Delta Modulator Design, Balkir Kayaalti, Ömer Ceri̇d, Günhan Dündar
A 0.18-$\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 …
Fpga Implementation Of A Hevc Deblocking Filter For Fast Processing Of Super High Resolution Applications, Awais Khan, Gulistan Raja
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 …
Variation Of Photovoltaic System Performance Due To Climatic And Geographical Conditions In Turkey, Betül Bektaş Eki̇ci̇
Variation Of Photovoltaic System Performance Due To Climatic And Geographical Conditions In Turkey, Betül Bektaş Eki̇ci̇
Turkish Journal of Electrical Engineering and Computer Sciences
This study focuses on the effect of climatic and geographical factors on the performance of photovoltaic systems. For this purpose, 4 different cities (Antalya, İstanbul, Elazığ, and Erzurum) from different climatic zones according to TS 825 Thermal Insulation Requirements in Buildings were selected. The monthly average global and diffuse solar radiation of the cities was calculated numerically with the long-term sunshine duration data (between 1990 and 2012) taken from the Turkish State Meteorological Service. The yearly electric energy generated by the grid-connected photovoltaic systems assumed to be located on the flat roofs of building samples were calculated for each of …
Integration Of Spectral And Spatial Information Via Local Covariance Matrices For Segmentation And Classification Of Hyperspectral Images, Uğur Ergül, Gökhan Bi̇lgi̇n
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 …
Leveraging Linked Open Data Information Extraction For Data Mining Applications, Rajesh Mahule, Om Prakash Vyas
Leveraging Linked Open Data Information Extraction For Data Mining Applications, Rajesh Mahule, Om Prakash Vyas
Turkish Journal of Electrical Engineering and Computer Sciences
The linked open data cloud, with a huge volume of data from heterogeneous and interlinked datasets, has turned the Web into a large data store. It has attracted the attention of both developers and researchers in the last few years, opening up new dimensions in machine learning and knowledge discovery. Information extraction procedures for these processes use different approaches, e.g., template-based, federated to multiple sources, fixed depth link traversal, etc. They are limited by problems in online access to datasets' SPARQL endpoints, such as servers being down for maintenance, bandwidth narrowing, limited numbers of access points to datasets in particular …
A Fast And Accurate Algorithm For Eye Opening Or Closing Detection Based On Local Maximum Vertical Derivative Pattern, Marzieh Tafreshi, Ali Mohammad Fotouhi
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 …
Design And Implementation Of A Digital Mppt Controller For A Photovoltaic Panel, Djamel Eddine Tourqui, Achour Betka, Atallah Smaili, Tayeb Allaoui
Design And Implementation Of A Digital Mppt Controller For A Photovoltaic Panel, Djamel Eddine Tourqui, Achour Betka, Atallah Smaili, Tayeb Allaoui
Turkish Journal of Electrical Engineering and Computer Sciences
This paper proposes a simplified design and hardware implementation of a digital maximum power point tracking (MPPT) controller for a photovoltaic (PV) panel using PIC microcontroller 16F877A embedded technology. The 3 most well-known algorithms, perturb & observe, hill-climbing, and incremental conductance, are considered and analyzed from a practical implementation point of view. The control board was developed using simple circuits and tested under resistive load conditions lower than the load of the maximum power point. The MPPT controller proved its effectiveness, providing maximum power to the load under changing weather conditions.
Effect Of Load Increase And Power System Stabilizer On Stability Delay Margin Of A Generator Excitation Control System, Şahi̇n Sönmez, Saffet Ayasun
Effect Of Load Increase And Power System Stabilizer On Stability Delay Margin Of A Generator Excitation Control System, Şahi̇n Sönmez, Saffet Ayasun
Turkish Journal of Electrical Engineering and Computer Sciences
This paper studies the impact of load increase and a power system stabilizer (PSS) on the stability delay margin of a single-machine-infinite-bus system including an automatic voltage regulator. An analytical method is proposed to determine the stability delay margin of the excitation control system. The proposed method first eliminates transcendental terms in the characteristic equation of the excitation system without making any approximation and transforms the transcendental characteristic equation into a regular polynomial. The key result of the elimination process is that the real roots of the new polynomial correspond to the imaginary roots of the transcendental characteristic equation. With …
A New Method To Reduce The Adverse Effects Of Wind Power On Power Quality Using Reactive Power Compensating Capacitors, Seyed Navid Zahedi, Amir Amini, Hamid Falaghi
A New Method To Reduce The Adverse Effects Of Wind Power On Power Quality Using Reactive Power Compensating Capacitors, Seyed Navid Zahedi, Amir Amini, Hamid Falaghi
Turkish Journal of Electrical Engineering and Computer Sciences
The usage of distributed generation resources, particularly distributed generation with renewable sources, has increased to generate electrical power close to consumers. One of the factors that can reduce penetration of distributed generation resources is the limitation of power quality, such as harmonic distortions. Distributed generation sources, in addition to producing power, due to using of power electronic converters and changing the power flow, increase harmonic currents. On the other hand, local compensation of reactive power by parallel capacitor banks is one of the effective methods to reduce power system losses and harmonic distortions. Since the capacitor impedance varies at different …
Highly Efficient Three-Phase Three-Level Multilevel Inverter Employing Different Commutation Strategies, Ammar Masaoud, Hew Wooi Ping, Saad Mekhilef, Hamza Belkamel
Highly Efficient Three-Phase Three-Level Multilevel Inverter Employing Different Commutation Strategies, Ammar Masaoud, Hew Wooi Ping, Saad Mekhilef, Hamza Belkamel
Turkish Journal of Electrical Engineering and Computer Sciences
This paper introduces a new three-phase three-level voltage source inverter. The proposed topology constitutes the conventional three-phase two-level inverter with three bidirectional switches. For purpose of generating the appropriate switching gate signals, two different commutation strategies are suggested and analyzed. A comparison between both strategies in terms of power losses and efficiency are presented. To ensure the feasibility of the proposed configuration with its suggested commutation strategies, the prototype of the proposed inverter was manufactured and the experimental results are given.
Lifetime Maximization Of Wireless Sensor Networks Using Particle Swarm Optimization, Aleem Kabeer Mir, Muhammad Zubair, Ijaz Mansoor Qureshi
Lifetime Maximization Of Wireless Sensor Networks Using Particle Swarm Optimization, Aleem Kabeer Mir, Muhammad Zubair, Ijaz Mansoor Qureshi
Turkish Journal of Electrical Engineering and Computer Sciences
Wireless sensor networks have multiple applications in intelligent environment and structural monitoring. The major challenge in wireless sensor networks is the power constraint. This paper deals with minimizing the energy utilization of wireless sensor nodes and maximizing their overall life span. The objective of our proposed scheme is to find a method for grouping sensors into the maximum number of distinct sensor cover sets to totally monitor the required area. This problem can be solved by using the disjoint cover set problem. Present optimization techniques take much time and deliver unsatisfactory results in large-scale networks. This paper proposes a technique …
Rlc Circuit Extraction With The Differential Evolution Algorithm For Conducted Electromagnetic Emission Model Of Integrated Circuits, Muhammed Emi̇n Başak, Ayten Kuntman
Rlc Circuit Extraction With The Differential Evolution Algorithm For Conducted Electromagnetic Emission Model Of Integrated Circuits, Muhammed Emi̇n Başak, Ayten Kuntman
Turkish Journal of Electrical Engineering and Computer Sciences
This paper examines the modeling of conducted electromagnetic emissions of integrated circuits. In this study, test circuits were designed and printed circuit boards were prepared to measure the input impedance at the power supply pin of the microcontroller. After S-parameter measurements of the test circuit were performed in a frequency range of 10 MHz to 2 GHz, Z-parameters were obtained via S-parameters. Next, the impedance--frequency curve of the test circuit's power supply pin, which consists of a microcontroller core, printed circuit board, conductive trace, and SMA connector global impedances, was obtained. Therefore, all the traces, printed circuit board, and SMA …
A Gis-Based Novel Active Monitoring System For Fiber Networks, Özer Koray Akdemi̇r, Taner Dursun, Sadik Arslan, Recep Benzer, Muhammet Ali̇ Akcayol
A Gis-Based Novel Active Monitoring System For Fiber Networks, Özer Koray Akdemi̇r, Taner Dursun, Sadik Arslan, Recep Benzer, Muhammet Ali̇ Akcayol
Turkish Journal of Electrical Engineering and Computer Sciences
In this study, a geographic information system (GIS)-based novel fiber network monitoring system has been developed to improve the operation and maintenance of fiber optic networks (FONs). The main aim of the developed system is to provide the required capabilities for both detailed digital modeling and central monitoring of FONs. The system can perform scheduled measurements and dispatch alarms if any fault or degradation is detected in the concerned FON. It also indicates the alarm locations on a map as a considerable contribution to decreasing mean time to repair. The developed monitoring system has more security features than others.
Modeling Based On 3d Finite Element Analysis And Experimental Study Of A 24-Slot 8-Pole Axial-Flux Permanent-Magnet Synchronous Motor For No Cogging Torque And Sinusoidal Back-Emf, Mehmet Güleç, Ersi̇n Yolaçan, Yücel Demi̇r, Oğuzhan Ocak, Meti̇n Aydin
Modeling Based On 3d Finite Element Analysis And Experimental Study Of A 24-Slot 8-Pole Axial-Flux Permanent-Magnet Synchronous Motor For No Cogging Torque And Sinusoidal Back-Emf, Mehmet Güleç, Ersi̇n Yolaçan, Yücel Demi̇r, Oğuzhan Ocak, Meti̇n Aydin
Turkish Journal of Electrical Engineering and Computer Sciences
This paper discusses cogging torque minimization techniques in surface-mounted, axial-flux, multirotor permanent magnet synchronous disc motors in order to eliminate cogging components and obtain sinusoidal back-EMF for low-speed applications. Cogging torque minimization techniques are examined in detail with a focus on magnet skewing and pole and rotor shifting in order to obtain zero cogging. Some magnet shape and rotor design alternatives with conventional skew planar magnets were investigated based on 3D finite element analysis (FEA). Improvements compared to unskewed reference axial-flux permanent magnet (AFPM) motor design are presented. A prototype AFPM motor was built and tested based on the analyses. …
The Classification Of Eeg Signals Using Discretization-Based Entropy And The Adaptive Neuro-Fuzzy Inference System, Mahmut Heki̇m
The Classification Of Eeg Signals Using Discretization-Based Entropy And The Adaptive Neuro-Fuzzy Inference System, Mahmut Heki̇m
Turkish Journal of Electrical Engineering and Computer Sciences
A novel feature extraction called discretization-based entropy is proposed for use in the classification of EEG signals. To this end, EEG signals are decomposed into frequency subbands using the discrete wavelet transform (DWT), the coefficients of these subbands are discretized into the desired number of intervals using the discretization method, the entropy values of the discretized subbands are calculated using the Shannon entropy method, and these are then used as the inputs of the adaptive neuro-fuzzy inference system (ANFIS). The equal width discretization (EWD) and equal frequency discretization (EFD) methods are used for the discretization. In order to evaluate their …
Improving The Srf Method To Compensate Low-Order Harmonics Under Nonsinusoidal Network Voltages, Javad Modarresi, Mehdi Fallah, Eskandar Ghokipour, Mohammad Tavakoli Bina
Improving The Srf Method To Compensate Low-Order Harmonics Under Nonsinusoidal Network Voltages, Javad Modarresi, Mehdi Fallah, Eskandar Ghokipour, Mohammad Tavakoli Bina
Turkish Journal of Electrical Engineering and Computer Sciences
Increasing the application of power in electronic devices has increased the harmonics in power systems. Numerous methods like the synchronous reference frame (SRF) and the p-q-based method have been suggested to overcome the effects of these harmonics. The conventional SRF method provides acceptable results in harmonic compensation of high-order harmonics (higher than the fourth order), but the transient response time will be drastically increased in the presence of low-order harmonics due to the existence of a conventional low-pass filter. Furthermore, if the load terminal voltages are distorted, then the conventional SRF method will become unable to implement load current compensation. …
Extracting The Region Of Interest From Mfl Signals, Ali Sadr, Raziyeh Sadat Okhovat
Extracting The Region Of Interest From Mfl Signals, Ali Sadr, Raziyeh Sadat Okhovat
Turkish Journal of Electrical Engineering and Computer Sciences
In this paper, we study the magnetic flux leakage (MFL) signals for detection of defects in ferromagnetic materials. MFL signals consist of a background that is not constant and is combined with noise. Since there are slight variations because of noise, any large distortion shows a defect. Here the estimation of the background and then the determination of a threshold to distinguish defects from noise have been used for locating defects. In this method, precise evaluation of these two parameters has a vital role on the defect detection. The concept of histograms has been employed for eliminating the effect of …
Relay Coordination Analysis And Protection Solutions For Smart Grid Distribution Systems, Mehmet Tan Turan, Erdi̇n Gökalp
Relay Coordination Analysis And Protection Solutions For Smart Grid Distribution Systems, Mehmet Tan Turan, Erdi̇n Gökalp
Turkish Journal of Electrical Engineering and Computer Sciences
Growing complexity of conventional power grids and their management, increasing power demand and energy quality expectations considering grid reliability, and efficiency and security concerns have triggered the evolution of smart grids. This is an expected result of implementing new technologies in existing grids, including renewable sources such as wind turbines and photovoltaic modules. With implementation of such new elements to the system, the protection concept should be considered by system regulators. In order to analyze protection problems, simulation-based analysis should be carried out before high-cost experimental studies. In this study, a simulation-based evaluation for a smart grid-based distribution system is …
Behavior-Based Detection Of Application Layer Distributed Denial Of Service Attacks During Flash Events, Renukadevi Saravanan, Saraswathi Shanmuganathan, Yogesh Palanichamy
Behavior-Based Detection Of Application Layer Distributed Denial Of Service Attacks During Flash Events, Renukadevi Saravanan, Saraswathi Shanmuganathan, Yogesh Palanichamy
Turkish Journal of Electrical Engineering and Computer Sciences
Distributed denial of service (DDoS) attacks are ever threatening to the developers and users of the Internet. DDoS attacks targeted at the application layer are especially difficult to be detected since they mimic the legitimate users' requests. The situation becomes more serious when they occur during flash events. A more sophisticated algorithm is required to detect such attacks during a flash crowd. A few existing works make use of flow similarity for differentiating flash crowds and DDoS, but flow characteristics alone cannot be used for effective detection. In this paper, we propose a novel mechanism for discriminating DDoS and flash …
Economic Assessment Of A Hybrid Turboexpander-Fuel Cell Gas Energy Extraction Plant, Ahmad Darabi, Ahmad Shariati, Reza Ghanaee, Ali Soleimani
Economic Assessment Of A Hybrid Turboexpander-Fuel Cell Gas Energy Extraction Plant, Ahmad Darabi, Ahmad Shariati, Reza Ghanaee, Ali Soleimani
Turkish Journal of Electrical Engineering and Computer Sciences
In this paper, a hybrid turboexpander-fuel cell (TE-FC) is investigated for extraction of electrical energy from high pressure gas in which the fuel cells are used for preheating the gas. Combination of expanders and fuel cells will reduce the fuel consumption and greenhouse gas emission. This study reveals that there are some circumstances in which the use of fuel cells in conjunction with a turboexpander is not recommended from an economic point of view. This paper seeks the region in which utilization of fuel cells along with a turboexpander presents maximum economic profit. Using the strategy provided in this paper …
Study Of Temperature Distribution In Light--Tissue Interaction Using The Fem, Ahmet Yasi̇n Çi̇tkaya, Şaban Seli̇m Şeker
Study Of Temperature Distribution In Light--Tissue Interaction Using The Fem, Ahmet Yasi̇n Çi̇tkaya, Şaban Seli̇m Şeker
Turkish Journal of Electrical Engineering and Computer Sciences
In this paper, the numerical modeling of interaction between light sources and living biological tissue is studied. One of the most important results of physical interactions of light with biological tissue are thermal changes, which are a consequence of absorption of light. The severity of the effects is dependent upon several factors, including exposure duration, wavelength of the beam, beam energy, tissue type, and the area that is exposed to the beam. The temperature response of tissue irradiation is governed by the extensively used Pennes bioheat equation in a 3-dimensional space. The Pennes equation is solved initially for a single-layer …
Feature Selection For Movie Recommendation, Zehra Çataltepe, Mahi̇ye Uluyağmur, Esengül Tayfur
Feature Selection For Movie Recommendation, Zehra Çataltepe, Mahi̇ye Uluyağmur, Esengül Tayfur
Turkish Journal of Electrical Engineering and Computer Sciences
TV users have an abundance of different movies they could choose from, and with the quantity and quality of data available both on user behavior and content, better recommenders are possible. In this paper, we evaluate and combine different content-based and collaborative recommendation methods for a Turkish movie recommendation system. Our recommendation methods can make use of user behavior, different types of content features, and other users' behavior to predict movie ratings. We gather different types of data on movies, such as the description, actors, directors, year, and genre. We use natural language processing methods to convert the Turkish movie …
Wavefront-Ray Grid Fdtd Algorithm, Mehmet Çi̇ydem
Wavefront-Ray Grid Fdtd Algorithm, Mehmet Çi̇ydem
Turkish Journal of Electrical Engineering and Computer Sciences
A finite difference time domain algorithm on a wavefront-ray grid (WRG-FDTD) is proposed in this study to reduce numerical dispersion of conventional FDTD methods. A FDTD algorithm conforming to a wavefront-ray grid can be useful to take into account anisotropy effects of numerical grids since it features directional energy flow along the rays. An explicit and second-order accurate WRG-FDTD algorithm is provided in generalized curvilinear coordinates for an inhomogeneous isotropic medium. Numerical simulations for a vertical electrical dipole have been conducted to demonstrate the benefits of the proposed method. Results have been compared with those of the spherical FDTD algorithm …
Prediction-Based Reversible Image Watermarking Using Artificial Neural Networks, Mahsa Afsharizadeh, Majid Mohammadi
Prediction-Based Reversible Image Watermarking Using Artificial Neural Networks, Mahsa Afsharizadeh, Majid Mohammadi
Turkish Journal of Electrical Engineering and Computer Sciences
In prediction-based reversible watermarking schemes, watermark bits are embedded in the prediction errors. An accurate prediction results in smaller prediction errors, more efficient embedding, and less distortion for the watermarked image. In this paper, an accurate prediction is made using artificial neural networks. Before the embedding operation, 2 neural networks are trained by the pixel values of the image. Then the trained neural networks predict the pixel values that are used in the embedding operation. Due to the training ability of the neural networks, the prediction will be more accurate than the averaging technique. Experimental results show that the proposed …
Quantitative Information Extraction From Gas Sensor Data Using Principal Component Regression, Ahmet Özmen, Beki̇r Mumyakmaz, Mehmet Ali̇ Ebeoğlu, Ci̇hat Taşaltin, İlke Gürol, Zafer Zi̇ya Öztürk, Deni̇z Dural
Quantitative Information Extraction From Gas Sensor Data Using Principal Component Regression, Ahmet Özmen, Beki̇r Mumyakmaz, Mehmet Ali̇ Ebeoğlu, Ci̇hat Taşaltin, İlke Gürol, Zafer Zi̇ya Öztürk, Deni̇z Dural
Turkish Journal of Electrical Engineering and Computer Sciences
This paper presents a novel use of the principal component analysis (PCA) and regression methods for quantitative feature extraction from gas sensor data. In this approach, PCA plots are interpreted by observing the locations of samples in the principal component domain. A trainable data processing system that also produces numerical output is designed to validate the method. The main advantages of this system are: 1) retrainability: once it is trained, it can be used for any gas set; 2) flexibility: adaptation to different targets does not require hardware modifications (if a sufficient number and variety of sensors are installed in …
Optimization With Genetic Algorithm Of Temperature-Dependent Fiber Length Of L-Band Edfa Gain, Murat Yücel, Damt Adnan Mustafa Mustafa
Optimization With Genetic Algorithm Of Temperature-Dependent Fiber Length Of L-Band Edfa Gain, Murat Yücel, Damt Adnan Mustafa Mustafa
Turkish Journal of Electrical Engineering and Computer Sciences
Erbium-doped fiber amplifiers (EDFAs) have great importance in long-distance communication. It is required to have equal gain for all signals that are transferred and to avoid loss in the receiver of long-distance communication systems. However, temperature dependence changes the output spectrum of the designed gain-flattening systems. In this study, each erbium-doped fiber (EDF) length of a two-stage L-band EDFA has been optimized using a genetic algorithm method; because of the temperature dependence of EDFAs, there is no general rule. Thus, a simple, fast, dynamic, and highly accurate model has been developed and obtained for different EDF lengths that will fix …
Variations And Relations Of Meteorological Parameters Between Upwind And Downwind Small-Scale Wind Turbine Rotor Area, Ercan İzgi̇, Mustafa Kemal Kaymak, Ahmet Öztopal, Bi̇hter Durna, Ahmet Duran Şahi̇n
Variations And Relations Of Meteorological Parameters Between Upwind And Downwind Small-Scale Wind Turbine Rotor Area, Ercan İzgi̇, Mustafa Kemal Kaymak, Ahmet Öztopal, Bi̇hter Durna, Ahmet Duran Şahi̇n
Turkish Journal of Electrical Engineering and Computer Sciences
Renewable energy sources are becoming increasingly important due to climate change and the energy crisis. Wind energy projects and applications in particular have been growing recently. Meteorological parameters such as wind speed, ambient temperature, relative humidity, and air pressure directly affect wind turbine electricity generation. Understanding the relationships among these parameters is necessary to determine wind energy potential and to predict electricity generation. The current work is based on data obtained from a 1.5 kW wind turbine constructed in İstanbul Technical University's meteorological park in Turkey. A one minute time interval was used in the data analysis. In this study, …
On Scalable Rdfs Reasoning Using A Hybrid Approach, Tuğba Külahcioğlu, Hasan Bulut
On Scalable Rdfs Reasoning Using A Hybrid Approach, Tuğba Külahcioğlu, Hasan Bulut
Turkish Journal of Electrical Engineering and Computer Sciences
Reasoning is a vital ability for semantic web applications since they aim to understand and interpret the data on the World Wide Web. However, reasoning of large data sets is one of the challenges facing semantic web applications. In this paper, we present new approaches for scalable Resource Description Framework Schema (RDFS) reasoning. Our RDFS specific term-based partitioning algorithm determines required schema elements for each data partition while eliminating the data partitions that will not produce any inferences. With the two-level partitioning approach, we are able to carry out reasoning with limited resources. In our hybrid approach, we integrate two …