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Full-Text Articles in Engineering

Design Of A Novel Usb Crypto Bridge Device, Orhan Şengül Jan 2015

Design Of A Novel Usb Crypto Bridge Device, Orhan Şengül

Turkish Journal of Electrical Engineering and Computer Sciences

Information technologies have emerging use of portable drives. Hence, the readability and security of the content is at great risk in the event that it is lost or stolen. An effective solution to this issue is the use of removable disks in encrypted form. In this paper, a novel USB device that has cryptobridge capability is proposed.


Enhancing Sliding Mode Control With Proportional Feedback And Feedforward: An Experimental Investigation On Speed Sensorless Control Of Pm Dc Motor Drives, Mehmet Dal Jan 2015

Enhancing Sliding Mode Control With Proportional Feedback And Feedforward: An Experimental Investigation On Speed Sensorless Control Of Pm Dc Motor Drives, Mehmet Dal

Turkish Journal of Electrical Engineering and Computer Sciences

This paper investigates the enhancement of sliding mode control (SMC) with the combined use of feedforward torque compensation and proportional error feedback control. The proposed enhancement is adapted to the control of permanent magnet (PM) DC motor drives by synthesis of the equivalent control equation augmented as proportional feedback and feedforward terms. A novel sliding function, introduced by utilizing the estimated load torque and the estimated rotor current, is examined and compared with another known sliding function obtained by nonideal differentiation of the estimated rotor speed. The significance of the proposed enhancements to SMC consists of the elimination of disturbance, …


Designing And Implementing A Reliable Thermal Monitoring System Based On The 1-Wire Protocol On Fpga For A Leo Satellite, Reza Omidi Gosheblagh, Karim Mohammadi Jan 2015

Designing And Implementing A Reliable Thermal Monitoring System Based On The 1-Wire Protocol On Fpga For A Leo Satellite, Reza Omidi Gosheblagh, Karim Mohammadi

Turkish Journal of Electrical Engineering and Computer Sciences

Thermal control and monitoring is one of the most important factors in the design of satellite systems. An appropriate thermal design should make sure that the satellite's sensitive components remain in their nominated range, even under the vacuum condition of outer space. To achieve this purpose, a reliable and stable monitoring system is required. This paper proposes a monitoring system based on the 1-wire protocol, which provides the reliability requirements in the sensor networking and bus controller sections. In the networking section, we outline some practical topologies and discuss on their complexity and reliability. Despite the fact that the point-to-point …


Discrete-Time Modeling Of Hamiltonian Systems, Yaprak Yalçin, Leyla Gören Sümer, Salman Kurtulan Jan 2015

Discrete-Time Modeling Of Hamiltonian Systems, Yaprak Yalçin, Leyla Gören Sümer, Salman Kurtulan

Turkish Journal of Electrical Engineering and Computer Sciences

The problem of discrete-time modeling of the lumped-parameter Hamiltonian systems is considered for engineering applications. Hence, a novel gradient-based method is presented, exploiting the discrete gradient concept and the forward Euler discretization under the assumption of the continuous Hamiltonian model is known. It is proven that the proposed discrete-time model structure defines a symplectic difference system and has the energy-conserving property under some conditions. In order to provide alternate discrete-time models, 3 different discrete-gradient definitions are given. The proposed models are convenient for the design of sampled-data controllers. All of the models are considered for several well-known Hamiltonian systems and …


Control Of Oxygen Excess Ratio In A Pem Fuel Cell System Using High-Order Sliding-Mode Controller And Observer, Seyed Mehdi Rakhtala, Abolfazl Ranjbar Noei, Reza Ghaderi, Elio Usai Jan 2015

Control Of Oxygen Excess Ratio In A Pem Fuel Cell System Using High-Order Sliding-Mode Controller And Observer, Seyed Mehdi Rakhtala, Abolfazl Ranjbar Noei, Reza Ghaderi, Elio Usai

Turkish Journal of Electrical Engineering and Computer Sciences

The main objective of this manuscript is to design a high-order sliding-mode observer to provide finite time estimation of unmeasurable states (x_4: oxygen mass, x_5: nitrogen mass) together with the oxygen excess ratio (ratio of the input oxygen flow to the reacted oxygen flow in the cathode). This is done by applying second-order sliding modes through either super twisting or suboptimal controllers to control the proton exchange membrane fuel cell's breathing. The estimated oxygen excess ratio is controlled in a closed-loop system using 2 distinct sliding-mode approaches: a cascaded super twisting controller and a single-loop suboptimal structure. Simulation results are …


A Robust Algorithm Based On A Failure-Sensitive Matrix For Fault Diagnosis Of Power Systems: An Application On Power Transformers, Yunus Bi̇çen, Faruk Aras Jan 2015

A Robust Algorithm Based On A Failure-Sensitive Matrix For Fault Diagnosis Of Power Systems: An Application On Power Transformers, Yunus Bi̇çen, Faruk Aras

Turkish Journal of Electrical Engineering and Computer Sciences

In this paper, a robust algorithm for fault diagnosis of power system equipment based on a failure-sensitive matrix (FSM) is presented. The FSM is a dynamic matrix structure updated by multiple measurements (online) and test results (offline) on the systems. The algorithm uses many different artificial intelligence and expert system methods for adaptively detecting the location of faults, emerging failures, and causes of failures. In this algorithm, all data obtained from the power transformer, which have various nonlinear input and output parameters, are processed using the parallel matrix structure of the FSM to reach a global solution quickly. The parameters …


A New Heuristic Method To Solve Unit Commitment By Using A Time-Variant Acceleration Coefficients Particle Swarm Optimization Algorithm, Arsalan Najafi, Mohsen Farshad, Hamid Falaghi Jan 2015

A New Heuristic Method To Solve Unit Commitment By Using A Time-Variant Acceleration Coefficients Particle Swarm Optimization Algorithm, Arsalan Najafi, Mohsen Farshad, Hamid Falaghi

Turkish Journal of Electrical Engineering and Computer Sciences

Unit commitment is one of the most important problems in power system operation. Because of the large amount of parameters and constraints, it contains a high level of complexity. In this paper a new method based on a time-variant acceleration coefficients particle swarm optimization algorithm has been proposed to solve the unit commitment problem. Integer coding (for satisfying minimum up/down constraints) and binary coding (for satisfying spinning reserve constraint) have been utilized in the proposed method. Simulations in the different cases have been done with different sizes. Numerical results have shown the superiority and better convergence of the proposed method …


Short-Term Load Forecasting Without Meteorological Data Using Ai-Based Structures, İdi̇l Işikli Esener, Tolga Yüksel, Mehmet Kurban Jan 2015

Short-Term Load Forecasting Without Meteorological Data Using Ai-Based Structures, İdi̇l Işikli Esener, Tolga Yüksel, Mehmet Kurban

Turkish Journal of Electrical Engineering and Computer Sciences

STLF is used in making decisions about economical power generation capacity, fuel purchasing, safety assessment, and power system planning in order to have economical power conditions. In this study, Turkey's 24-hour-ahead load forecasting without meteorological data is studied. ANN, wavelet transform and ANN, wavelet transform and RBF NN, and EMD and RBF NN structures are used in STLF procedures. Local holidays' historical load data are changed into data with normal day characteristics, and the estimation results of these days are not included in error computation. To obtain more accurate results, a regulation on forecasted loads is proposed. Regulated and unregulated …


An Intelligence-Based Islanding Detection Method Using Dwt And Ann, Mehrdad Heidari, Ghodratollah Seifossadat, Morteza Razaz Jan 2015

An Intelligence-Based Islanding Detection Method Using Dwt And Ann, Mehrdad Heidari, Ghodratollah Seifossadat, Morteza Razaz

Turkish Journal of Electrical Engineering and Computer Sciences

In this paper, a new method based on artificial neural network (ANN) and discrete wavelet transform (DWT) is proposed for electrical islanding detection. Transient signals produced during an event are used in the proposed method. ANN is trained to classify the transient events as islanding and nonislanding. The required features for classifying are extracted through DWT of voltage and current transient signals. The proposed method is then simulated on a medium voltage distribution system of CIGRE with 2 kinds of DGs. Results show that this method can detect electrical islands more rapidly and accurately.


Epilepsy Diagnosis Using Artificial Neural Network Learned By Pso, Nesi̇be Yalçin, Gülay Tezel, Ci̇han Karakuzu Jan 2015

Epilepsy Diagnosis Using Artificial Neural Network Learned By Pso, Nesi̇be Yalçin, Gülay Tezel, Ci̇han Karakuzu

Turkish Journal of Electrical Engineering and Computer Sciences

Electroencephalogram (EEG) is used routinely for diagnosis of diseases occurring in the brain. It is a very useful clinical tool in the classification of epileptic seizures and the diagnosis of epilepsy. In this study, epilepsy diagnosis has been investigated using EEG records. For this purpose, an artificial neural network (ANN), widely used and known as an active classification technique, is applied. The particle swarm optimization (PSO) method, which does not need gradient calculation, derivative information, or any solution of differential equations, is preferred as the training algorithm for the ANN. A PSO-based neural network (PSONN) model is diversified according to …


Dynamic Modeling Of Modular Fuel Cell For Maximum Power Point Tracking And Torque Ripple Reduction In Direct Torque Control Of Induction Motor, Majid Valizadeh, Mohammad Reza Feyzi, Ebrahim Babaei, Mehran Sabahi Jan 2015

Dynamic Modeling Of Modular Fuel Cell For Maximum Power Point Tracking And Torque Ripple Reduction In Direct Torque Control Of Induction Motor, Majid Valizadeh, Mohammad Reza Feyzi, Ebrahim Babaei, Mehran Sabahi

Turkish Journal of Electrical Engineering and Computer Sciences

This paper presents a comprehensive dynamic model of a proton exchange membrane fuel cell (FC) based on the electrical empirical model. The presented model is useful for online control as well as having suitable accuracy. FC stacks produce a DC voltage with a ratio of 2:1 in output from no-load to full-load. In vehicles that are equipped with FCs, the output voltage of the FC is drastically changed because the power and torque of the vehicle change with the driving cycle. In order to improve the performance of the direct torque control of induction motors, the modular structure of a …


Quality Of Service Assessment: A Case Study On Performance Benchmarking Of Cellular Network Operators In Turkey, Rana Kadioğlu, Yaser Dalveren, Ali̇ Kara Jan 2015

Quality Of Service Assessment: A Case Study On Performance Benchmarking Of Cellular Network Operators In Turkey, Rana Kadioğlu, Yaser Dalveren, Ali̇ Kara

Turkish Journal of Electrical Engineering and Computer Sciences

This paper presents findings on performance benchmarking of cellular network operators in Turkey. Benchmarking is based on measurements of standard key performance indicators (KPIs) in one of the metropolitan cities of Turkey, Ankara. Performance benchmarking is formulated by incorporating customer perception by conducting surveys on how important KPIs are from the user's point of view. KPIs are measured, with standard test equipment, by drive test method on specified routes. According to the performance benchmarking results, the GSM and UMTS network operators achieving the best performance were determined in Ankara. Speech qualities of network operators, as the most popular service, were …


A Fault Detection, Diagnosis, And Reconfiguration Method Via Support Vector Machines}, Rana Ortaç Kabaoğlu Jan 2015

A Fault Detection, Diagnosis, And Reconfiguration Method Via Support Vector Machines}, Rana Ortaç Kabaoğlu

Turkish Journal of Electrical Engineering and Computer Sciences

This paper presents a fault detection, diagnosis, and reconfiguration method based on support vector machines. This method is appropriate for certain or predetermined faults and involves a fault detection and diagnosis unit and an online controller selection type reconfiguration mechanism. In this method, when a fault is detected and diagnosed by the fault detection and diagnosis unit, a suitable controller, which has been determined via an optimization algorithm in an off-line fashion, is activated to maintain proper closed-loop performance of the system in an on-line manner. In the detection, diagnosis, and reconfiguration stages of the method, support vector classification and …


A New Hysteresis Band Current Control Technique For A Shunt Active Filter, Murat Kale, Engi̇n Özdemi̇r Jan 2015

A New Hysteresis Band Current Control Technique For A Shunt Active Filter, Murat Kale, Engi̇n Özdemi̇r

Turkish Journal of Electrical Engineering and Computer Sciences

This paper proposes a hysteresis band (HB) current control technique to reduce the power losses in a shunt active filter. During a switching period in the zero-crossing region, the inverter output current flows through a transistor. By changing the direction, it flows through the free-wheeling diode of the same switch in an inverter leg, or vice versa. The shunt active filter current typically has 6 zero-crossing regions during a fundamental frequency cycle. This paper presents a HB current control technique where there is not any switching in these 6 zero-crossing regions per period, which results in reducing the power losses. …


Dwmt Transceiver Equalization Using Overlap Fde For Downlink Adsl, Arsla Khan, Sobia Baig, Tabassum Nawaz Jan 2015

Dwmt Transceiver Equalization Using Overlap Fde For Downlink Adsl, Arsla Khan, Sobia Baig, Tabassum Nawaz

Turkish Journal of Electrical Engineering and Computer Sciences

Discrete wavelet multitone (DWMT) modulation is a wavelet transform based technique implemented using perfect reconstruction filter banks. It has been recently proposed for various wireline channels such as digital subscriber loops (DSLs) as a solution to the problems posed by a discrete multitone (DMT) transceiver including interblock interference (IBI) and lower spectral efficiency due to the employment of a cyclic prefix (CP) in the guard interval (GI) for DMT symbols. The greater side lobe attenuation offered by wavelet filter banks results in improved spectral containment and lower IBI in DWMT transceivers. However, no standard equalization technique exists for a DWMT …


Using The Finite Element Method To Calculate Parameters For A Detailed Model Of Transformer Winding For Partial Discharge Research, Seyed Mohammad Hassan Hosseini, Seyed Mohsen Enjavi Madar, Mehdi Vakilian Jan 2015

Using The Finite Element Method To Calculate Parameters For A Detailed Model Of Transformer Winding For Partial Discharge Research, Seyed Mohammad Hassan Hosseini, Seyed Mohsen Enjavi Madar, Mehdi Vakilian

Turkish Journal of Electrical Engineering and Computer Sciences

Power transformers are considered to be one of the most essential and costly pieces of equipment in a power system. Identifying insulation faults in the shortest possible time prevents the occurrence of irreparable damage. Partial discharge (PD) is one of the most significant insulation faults. The first step in the study of PD is the precise modeling of transformer winding at high frequencies. In this paper, the finite element method is used to calculate the parameters for a detailed model of transformer winding. For this reason, a detailed model of transformer winding and the analytic formulations are first presented for …


Moving As A Whole: Multirobot Traveling Problem Constrained By Connectivity, Yun Wang, Cheng Hu Jan 2015

Moving As A Whole: Multirobot Traveling Problem Constrained By Connectivity, Yun Wang, Cheng Hu

Turkish Journal of Electrical Engineering and Computer Sciences

A multirobot system provides many advantages over a single robot. In certain situations, robots need to maintain global connectivity while proceeding through tasks such as traveling to spots of interest in an area. This paper formulates the problem of multiple robots traveling while constrained by connectivity and analyzes the limits of increase in total traveling distance (TTD) caused by connectivity constraints. A connection condition is proposed and proven, which can be used to direct the design of solutions. Two algorithms satisfying the connection condition, connected nearest neighbor (CNN) and bold Lin-Kernighan heuristic (B-LKH), are proposed to solve this problem, which …


Novel Congestion Control Algorithms For A Class Of Delayed Networks, Shoorangiz Shams Shamsabad Farahani, Mohammad Reza Jahed Motlagh, Mohammad Ali Nekoui Jan 2015

Novel Congestion Control Algorithms For A Class Of Delayed Networks, Shoorangiz Shams Shamsabad Farahani, Mohammad Reza Jahed Motlagh, Mohammad Ali Nekoui

Turkish Journal of Electrical Engineering and Computer Sciences

Time delays are often instability sources and give rise to undesired oscillation and performance degradation, so it is necessary to consider delay in general congestion control schemes. In this paper, a new system model for wireless sensor networks (WSNs) is established in discrete time, subsystems including delay are presented, and the overall model is achieved by blending these subsystems. For controller synthesis, common quadratic Lyapunov functions and a new approach based on nonquadratic Lyapunov functions are utilized, and a controller is designed to stabilize each subsystem. The controller synthesis results are expressed in terms of linear matrix inequalities. Moreover, the …


Detection Of Microcalcification In Digitized Mammograms With Multistable Cellular Neural Networks Using A New Image Enhancement Method: Automated Lesion Intensity Enhancer (Alie), Levent Ci̇vci̇k, Burak Yilmaz, Yüksel Özbay, Gani̇me Di̇lek Emli̇k Jan 2015

Detection Of Microcalcification In Digitized Mammograms With Multistable Cellular Neural Networks Using A New Image Enhancement Method: Automated Lesion Intensity Enhancer (Alie), Levent Ci̇vci̇k, Burak Yilmaz, Yüksel Özbay, Gani̇me Di̇lek Emli̇k

Turkish Journal of Electrical Engineering and Computer Sciences

Microcalcification detection is a very important issue in early diagnosis of breast cancer. Generally physicians use mammogram images for this task; however, sometimes analyzing these images become a hard task because of problems in images such as high brightness values, dense tissues, noise, and insufficient contrast level. In this paper, we present a novel technique for the task of microcalcification detection. This technique consists of three steps. The first step is focused on removing pectoral muscle and unnecessary parts from the mammogram images by using cellular neural networks (CNNs), which makes this a novel process. In the second step, we …


An Aggregate Indicator For Mobile Application Quality Assessment, Paul Pocatilu, Ion Ivan, Alin Zamfiroiu, Catalin Boja Jan 2015

An Aggregate Indicator For Mobile Application Quality Assessment, Paul Pocatilu, Ion Ivan, Alin Zamfiroiu, Catalin Boja

Turkish Journal of Electrical Engineering and Computer Sciences

The mobile applications environment has a multitude of particularities generated by the complex system of devices, hardware, and software profiles and categories of users. The mobile industry has also evolved rapidly in the last 5 years from single-core mobile platforms to multiple-core mobile application platforms, able to compete in terms of user services with notebooks. New types of devices, like tablets, or shifts in human-computer interface paradigms from button click to screen touch, have opened new perspectives both for users and software developers. This requires an adaptable approach for performance analysis in terms of total quality management for software projects. …


Calculation Of Surface Leakage Currents On High Voltage Insulators By Ant Colony Algorithm-Supported Fem, Dursun Öztürk, Mehmet Cebeci̇ Jan 2015

Calculation Of Surface Leakage Currents On High Voltage Insulators By Ant Colony Algorithm-Supported Fem, Dursun Öztürk, Mehmet Cebeci̇

Turkish Journal of Electrical Engineering and Computer Sciences

The weakness of the outer insulation at high voltages is the reduction of the surface resistance as a result of the environmental pollution yielding formation of flashover due to the surface leakage currents. In this study, it was shown how to calculate the surface leakage currents resulting in flashover in polluted insulators and therefore power cuts by means of the ant colony algorithm (ACA). For this purpose, first, field distribution on the sample insulator surface in question was defined by the Laplace equation ($\nabla^{2}$V = 0). With the help of the finite element method (FEM), the Laplace equation was obtained …


Rfid Card Security For Public Transportation Applications Based On A Novel Neural Network Analysis Of Cardholder Behavior Characteristics, Gürsel Düzenli̇ Jan 2015

Rfid Card Security For Public Transportation Applications Based On A Novel Neural Network Analysis Of Cardholder Behavior Characteristics, Gürsel Düzenli̇

Turkish Journal of Electrical Engineering and Computer Sciences

This paper proposes a novel approach that applies neural network forecasting to security for closed-loop prepaid cards based on low-cost technologies such as RFID and 1-Wire. The security vulnerability of low-cost RFID closed-loop prepaid card systems originates mostly from the card itself. Criminal organizations counterfeit or clone card data. Although high-security prepaid cards exist, they are often too expensive for transport ticketing, and even their security is not guaranteed for a well-defined period of time. Therefore, data encryption systems are used widely against counterfeiting with success. However, it has not been possible to develop countermeasures with comparable success against cloning. …


Active And Reactive Power Transmission Loss Allocation To Bilateral Contracts Through Game Theory Techniques, Hamed Nafisi, Hossein Mahdinia Roudsari, Seyed Hossein Hosseinian, Hossein Askarian Abyaneh, Vahid Rasouli Disfani Jan 2015

Active And Reactive Power Transmission Loss Allocation To Bilateral Contracts Through Game Theory Techniques, Hamed Nafisi, Hossein Mahdinia Roudsari, Seyed Hossein Hosseinian, Hossein Askarian Abyaneh, Vahid Rasouli Disfani

Turkish Journal of Electrical Engineering and Computer Sciences

Transmission loss has a considerable effect in overall power generation. For fairly distributing the charge of losses to generators and consumers in a deregulated power system, the allocation of this loss is very important. Game-theoretic methods seem fairer for share determination of each participant of a coalition with no discrimination. In this paper, the active and reactive power transmission losses are allocated to bilateral transactions simultaneously through load flow calculations and cooperative game theory solutions. The loss allocation problem and each bilateral transaction are treated as a game and a player of the game, correspondingly. Two game theory-based approaches, the …


A Real-Time Life-Care Monitoring Framework: Warnred Hardware And Software Design, Gamze Doğali Çeti̇n, Özdemi̇r Çeti̇n, Cüneyt Bayilmiş Jan 2015

A Real-Time Life-Care Monitoring Framework: Warnred Hardware And Software Design, Gamze Doğali Çeti̇n, Özdemi̇r Çeti̇n, Cüneyt Bayilmiş

Turkish Journal of Electrical Engineering and Computer Sciences

It is shown by many statistical studies that the senior population, especially in developed countries, is in an increasing trend. For many reasons they tend to have in-home health care providers. The recent studies on biomedical information management focused on remote health monitoring frameworks including heart rate monitoring systems, glucose measurements for diabetics, and remote monitoring EEG and ECG. The main purposes of these studies are timely response to emergency situations and ensuring that the person is in a stable condition. In this study, developed via a system-on-chip circuit, we process the data collected from subjects through a temperature sensor …


Effect Of Nonuniform Varying Delay On The Rate Of Convergence In Averaging-Based Consensus, Onur Ci̇han, Mehmet Akar Jan 2015

Effect Of Nonuniform Varying Delay On The Rate Of Convergence In Averaging-Based Consensus, Onur Ci̇han, Mehmet Akar

Turkish Journal of Electrical Engineering and Computer Sciences

This paper discusses the effect of nonuniform varying communication delay on distributed consensus algorithms in discrete time. After introducing the delayed mathematical model, we first investigate the ergodicity of the delayed system using the properties of scrambling matrices. Subsequently, the effect of nonuniform varying delay on convergence is examined. It is shown theoretically that nonuniform delay is not detrimental to the convergence rate of the algorithm for directed acyclic graphs. The results are also illustrated with several numerical examples.


Impact Of Repeaters On The Performance Of Indoor Visible Light Communications, Refi̇k Çağlar Kizilirmak Jan 2015

Impact Of Repeaters On The Performance Of Indoor Visible Light Communications, Refi̇k Çağlar Kizilirmak

Turkish Journal of Electrical Engineering and Computer Sciences

In this study, we examine the performance of fixed gain amplify-and-forward repeaters for visible light communication (VLC) systems. We present the wireless optical channel model for VLC with the repeater and we evaluate the bit-error-rate (BER) performance for pulse-position modulation over the multipath channel with additive white Gaussian noise. The results reveal that when a repeater is placed, both the BER and the illuminance performance can be improved at any location in a typical office space. The benefit of VLC repeaters is also discussed when the channel from the source to the destination is shadowed. It is found that when …


Robust Speed Controller Design For Induction Motors Based On Ifoc And Kharitonov Theorem, Bijan Moaveni, Mojtaba Khorshidi Jan 2015

Robust Speed Controller Design For Induction Motors Based On Ifoc And Kharitonov Theorem, Bijan Moaveni, Mojtaba Khorshidi

Turkish Journal of Electrical Engineering and Computer Sciences

In this paper, robust PI controllers are designed to control the speed of induction motors based on a vector control strategy. The design methodology defines the robust stability and robust performance regions in the $k_{p}-k_{i}$ (PI controller coefficients) plane using the Kharitonov theorem. In the control system design procedure, a nonlinear induction motor is modeled as an uncertain linear model. The procedure of modeling the uncertainties is presented. The required scientific foundations for designing a robust PI controller are also introduced in the general case while the necessary equations are derived. In the final step, the design procedure for a …


Exact Solution Of Conducting Half Plane Problems In Terms Of A Rapidly Convergent Series And An Application Of The Multiplicative Calculus, Ali̇ Uzer Jan 2015

Exact Solution Of Conducting Half Plane Problems In Terms Of A Rapidly Convergent Series And An Application Of The Multiplicative Calculus, Ali̇ Uzer

Turkish Journal of Electrical Engineering and Computer Sciences

The problem of cylindrical wave incidence on a conducting half plane has been considered. A modal solution for Green's function of the problem is transformed into contour integral representations in a complex plane. Some contour deformations and changes of variables are then made for the integrals. Finally, the resultant integrals are transformed back into a series, which converges rapidly to the exact solution when the observation angles are close to the reflection/shadow boundaries (RSBs) of the conducting half plane. The multiplicative calculus is employed in deriving an expression that can be used for obtaining approximate solutions when the observation angles …


Optimal Backup Parent Pools For Resilient Multicast Trees On Peer-To-Peer Networks, Emrullah Turhan Tunali, Müge Sayit Jan 2015

Optimal Backup Parent Pools For Resilient Multicast Trees On Peer-To-Peer Networks, Emrullah Turhan Tunali, Müge Sayit

Turkish Journal of Electrical Engineering and Computer Sciences

Due to churn as well as node and link failures in peer-to-peer (P2P) networks, providing resilient multicast is a challenging issue, particularly for overlay trees. In this work, we first study analytical properties of the backup parent pool that aims at improving the resilience of overlay multicast trees in P2P video streaming. We then present a novel greedy degree-constrained multicast tree construction algorithm that addresses the tradeoffs between maximizing resiliency, maximizing bandwidth utilization, and minimizing delay. The choice of essential design parameters is studied together with seamlessness of the streaming under a variety of fault scenarios. Simulation results indicate that …


Detection Of Stator Winding Fault In Induction Motor Using Instantaneous Power Signature Analysis, Ahmet Küçüker, Mehmet Bayrak Jan 2015

Detection Of Stator Winding Fault In Induction Motor Using Instantaneous Power Signature Analysis, Ahmet Küçüker, Mehmet Bayrak

Turkish Journal of Electrical Engineering and Computer Sciences

Stator interturn faults are one of the most common faults occurring in induction motors. Early detection of interturn short circuit is important to reduce repair costs. Axial leakage monitoring, zero-sequence components, negative sequence current, and motor current signature analysis have been used for fault detection in early states. In the paper, the instantaneous power signature analysis technique is used to detect these faults, and experimental results for healthy and faulty motors are shown and discussed.