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Articles 2941 - 2970 of 3096
Full-Text Articles in Physical Sciences and Mathematics
Sturm-Liouville Equation: The Bridge Between Eigenvalue And Green's Function Problems, Levent Sevgi̇
Sturm-Liouville Equation: The Bridge Between Eigenvalue And Green's Function Problems, Levent Sevgi̇
Turkish Journal of Electrical Engineering and Computer Sciences
This article is intended as an educational aid and discusses guided wave propagation problems that are modeled via the Sturm-Liouville equation in electromagnetics. The bridge between source-free (eigenvalue) and source-driven (Green's function) problems that are represented by the same Sturm-Liouville equation is emphasized. The presentation focuses on representation of an arbitrary source from the features (eigenfunctions) of the problem geometry and extraction of the eigenvalues of a problem from propagation characteristics (Green's function) on a canonical problem; a homogeneously filled parallel plate waveguide with non-penetrable boundaries
Agents For Integrating Distributed Data For Complex Computations, Ahmed M. Khedr, Raj Bhatnagar
Agents For Integrating Distributed Data For Complex Computations, Ahmed M. Khedr, Raj Bhatnagar
Turkish Journal of Electrical Engineering and Computer Sciences
Algorithms for many complex computations assume that all the relevant data are available on a single node of a computer network. In the emerging distributed and networked knowledge environments, databases relevant for computations may reside on a number of nodes connected by a communication network. These data resources cannot be moved to other network sites due to privacy, security, and size considerations. The desired global computation must be decomposed into local computations to match the distribution of data across the network. The capability to decompose computations must be general enough to handle different distributions of data and different participating nodes …
Engineering Education In The 21st Century: Issues And Perspectives, Leopold B. Felsen
Engineering Education In The 21st Century: Issues And Perspectives, Leopold B. Felsen
Turkish Journal of Electrical Engineering and Computer Sciences
No abstract provided.
Electronic Publishing For Engineering Education, Donald G. Dudley
Electronic Publishing For Engineering Education, Donald G. Dudley
Turkish Journal of Electrical Engineering and Computer Sciences
Electronic transmission of text is a revolution in progress with a profound effect on engineering education. As with all revolutions, the result is both a threat and a promise. The promise is the ease and speed of dissemination of text. The threat involves serious difficulties that arise in efforts to protect the intellectual property rights of the authors and publishers of the technical information. In this paper, we discuss both the threat and the promise. We highlight the differences in dealing with books and with journals. We give a wide range of examples from both inside of and outside of …
Speaking With Numbers: Scientific Literacy And Public Understanding Of Science, Levent Sevgi̇
Speaking With Numbers: Scientific Literacy And Public Understanding Of Science, Levent Sevgi̇
Turkish Journal of Electrical Engineering and Computer Sciences
Public understanding of science and scientific literacy is discussed. Scientific method, scientific process and scientific filter are reviewed accordingly. Basic terms of measurement and numerical calculation are outlined. Finally, fundamental requirements of scientific literacy and critical response skills are presented.
Infusing Technical Communication And Teamwork Within The Ece Curriculum, By April Kedrowicz, Sundy Watanabe, Damon Hall, Cynthia Furse
Infusing Technical Communication And Teamwork Within The Ece Curriculum, By April Kedrowicz, Sundy Watanabe, Damon Hall, Cynthia Furse
Turkish Journal of Electrical Engineering and Computer Sciences
This paper highlights a unique approach to infusing formal training and practice in oral and written communication and teamwork development in the Department of Electrical and Computer Engineering (ECE) at the University of Utah. Faculty and graduate (Ph.D.) students from the College of Humanities have teamed up with faculty from engineering to develop communication and teamwork instruction that is integrated into the existing engineering curriculum. These skills are used as a vehicle to provide better understanding of engineering concepts and their applications.
Introducing Students To Communications Concepts Using Optical And Low-Power Wireless Devices, James M. Conrad, Ivan Howitt
Introducing Students To Communications Concepts Using Optical And Low-Power Wireless Devices, James M. Conrad, Ivan Howitt
Turkish Journal of Electrical Engineering and Computer Sciences
Wireless communication has become an important feature for commercial products and a popular research topic within the last ten years. There are now more mobile phone subscriptions than wired-line subscriptions. Lately, one area of commercial interest has been low-cost, low-power, and short-distance wireless communication used for "personal wireless networks." Technology advancements are providing smaller and more cost effective devices for integrating computational processing, wireless communication, and a host of other functionalities. These embedded communications devices will be integrated into applications ranging from homeland security to industry automation and monitoring. They will also enable custom tailored engineering solutions, creating a revolutionary …
Electrical And Computer Engineering Education In The 21^{St} Century: Issues, Perspectives And Challenges, Levent Sevgi̇
Electrical And Computer Engineering Education In The 21^{St} Century: Issues, Perspectives And Challenges, Levent Sevgi̇
Turkish Journal of Electrical Engineering and Computer Sciences
No abstract provided.
Two, Three And Four-Dimensional Electromagnetics Using Differential Forms, Karl F. Warnick, Peter Russer
Two, Three And Four-Dimensional Electromagnetics Using Differential Forms, Karl F. Warnick, Peter Russer
Turkish Journal of Electrical Engineering and Computer Sciences
The exterior calculus of differential forms provides a mathematical framework for electromagnetic field theory that combines much of the generality of tensor analysis with the computational simplicity and concreteness of the vector calculus. We review the pedagogical aspects of the calculus of differential forms in providing distinct representations of field intensity and flux density, physically meaningful graphical representations for sources, fields, and fluxes, and a picture of the curl operation that is as simple and intuitive as that of the gradient and divergence. To further highlight the benefits of differential forms notation, we demonstrate the flexibility of the calculus of …
Secure Digital Communication Using Chaotic Symbolic Dynamics, Ajeesh P. Kurian, Sadasivan Puthusserypady
Secure Digital Communication Using Chaotic Symbolic Dynamics, Ajeesh P. Kurian, Sadasivan Puthusserypady
Turkish Journal of Electrical Engineering and Computer Sciences
One of the major hurdles in implementing chaotic communication schemes is the synchronization of chaotic systems. For the last two decades, numerous contributions of varying successes have been made by researchers from different disciplines for the synchronization of chaotic systems. Symbolic dynamics based synchronization method is shown to be capable of providing high quality synchronization (HQS), which is essential for reliable communication. In this work, using this method, a secure digital communication system is proposed. The well known piece-wise linear 1-D map such as tent map and Bernoulli shift map are used for this study. Since the information is dynamically …
A Corpus-Based Concatenative Speech Synthesis System For Turkish, Haşi̇m Sak, Tunga Güngör, Yaşar Safkan
A Corpus-Based Concatenative Speech Synthesis System For Turkish, Haşi̇m Sak, Tunga Güngör, Yaşar Safkan
Turkish Journal of Electrical Engineering and Computer Sciences
Speech synthesis is the process of converting written text into machine-generated synthetic speech. Concatenative speech synthesis systems form utterances by concatenating pre-recorded speech units. Corpus-based methods use a large inventory to select the units to be concatenated. In this paper, we design and develop an intelligible and natural sounding corpus-based concatenative speech synthesis system for the Turkish language. The implemented system contains a front-end comprised of text analysis, phonetic analysis, and optional use of transplanted prosody. The unit selection algorithm is based on commonly used Viterbi decoding algorithm of the best-path in the network of the speech units using spectral …
Speech Pre-Processing For Pitch And Pitch-Cylce Evolutions Smoothing, Hassan Farsi
Speech Pre-Processing For Pitch And Pitch-Cylce Evolutions Smoothing, Hassan Farsi
Turkish Journal of Electrical Engineering and Computer Sciences
In low bit rate speech coders, pitch is usually transmitted once per frame and, when needed, the intermediate pitch values are obtained by interpolation between 2 adjacent pitch values. Although pitch usually evolves slowly, sometimes it has irregular variations and the estimated pitch differs from the real one. In addition, some speech coders, e.g., waveform interpolation coders, rely on smooth pitch-cycle evolutions to extract speech model parameters in the analysis stage. However, non-stationary characteristics of speech may lead to inaccurate estimation of the parameters. This affects the synthesised speech quality. We propose a pre-processor, which modifies the residual speech signal …
A Pi Controller Based On Gain-Scheduling For Synchronous Generator, Alireza Sedaghati
A Pi Controller Based On Gain-Scheduling For Synchronous Generator, Alireza Sedaghati
Turkish Journal of Electrical Engineering and Computer Sciences
In this paper a gain- scheduling scheme of a proportional integral (GSPI) controller is proposed for a synchronous generator. In presented scheme, both proportional and integral gains are allowed to vary within a predetermined range. In order to validate the effectiveness of GSPI controller, simulation studies for a single-machine infinite bus power system are used .The results verify improved performance of GSPI controller comparing to conventional AVR under various operating conditions.
Adaptive 3d Visual Servo Control Of Robot Manipulators Via Composite Camera Inputs, Türker Şahi̇n, Erkan Zergeroğlu
Adaptive 3d Visual Servo Control Of Robot Manipulators Via Composite Camera Inputs, Türker Şahi̇n, Erkan Zergeroğlu
Turkish Journal of Electrical Engineering and Computer Sciences
This paper considers the problem of position control of robot manipulators via visual servoing in the presence of uncertainty associated with the robot dynamics and the vision system. Specifically, an adaptive controller is designed to compensate for the uncertainties associated with the mechanical parameters of the robot manipulator and the intrinsic parameters of the cameras. The 3D visual information is obtained from the composite inputs of two separate cameras placed in the robot work space. Despite the uncertainties associated with the camera system and robot dynamics the proposed adaptive controller achieves asymptotic end effector position tracking. A Lyapunov based approach …
Human Identification Using Gait, Murat Eki̇nci̇
Human Identification Using Gait, Murat Eki̇nci̇
Turkish Journal of Electrical Engineering and Computer Sciences
Gait refers to the style of walking of an individual. This paper presents a view-invariant approach for human identification at a distance, using gait recognition. Recognition of a person from their gait is a biometric of increasing interest. Based on principal component analysis (PCA), this paper describes a simple, but efficient approach to gait recognition. Binarized silhouettes of a motion object are represented by 1-D signals, which are the basic image features called distance vectors. The distance vectors are differences between the bounding box and silhouette, and are extracted using 4 projections of the silhouette. Based on normalized correlation of …
Uplink Practical Capacity And Interference Statistics Of Wcdma Cigar-Shaped Microcells For Highways In Rural Zones With Non-Uniform Spatial Traffic Distribution And Imperfect Power Control, Bazil Taha Ahmed, Miguel Calvo Ramon, Leandro De Haro-Ariet
Uplink Practical Capacity And Interference Statistics Of Wcdma Cigar-Shaped Microcells For Highways In Rural Zones With Non-Uniform Spatial Traffic Distribution And Imperfect Power Control, Bazil Taha Ahmed, Miguel Calvo Ramon, Leandro De Haro-Ariet
Turkish Journal of Electrical Engineering and Computer Sciences
The capacity (the maximum number of users per sector that the system can support) and the interference statistics (expected value and variance) of sectors composed of cigar-shaped WCDMA microcells are studied. A model of 5 microcells is used to analyze the uplink capacity and interference statistics. The microcells are assumed to exist in rural zone highways. The capacity and the interference statistics of the microcells are studied for different non-uniform spatial traffic distributions. As user density decreases away from the base station, the capacity of the sector increases due to the reduced total power transmitted by the interfering users.
An Ann Based Approach To Improve The Distance Relaying Algorithm, Hassan Khorashadi Zadeh, Zuyi Li
An Ann Based Approach To Improve The Distance Relaying Algorithm, Hassan Khorashadi Zadeh, Zuyi Li
Turkish Journal of Electrical Engineering and Computer Sciences
This paper presents an artificial neural network- (ANN) based approach to improve the performance of the distance relaying algorithm. The proposed distance relay uses magnitudes of voltages and currents as input signals to find fault locations. In this approach, an ANN has been included in the protection algorithm as an extension of the existing methods, which improves the reliability of the protection operation. The design procedure of the proposed relay is presented in detail. Simulation studies are performed and the influence of changing system parameters, such as fault resistance and source impedance, is studied. Performance studies show that the proposed …
State Of The Art For Differential Circuits In Wireless Transceivers: A New Wideband Active Balun In Sige Bicmos Technology, Balwant Godara, Alain Fabre
State Of The Art For Differential Circuits In Wireless Transceivers: A New Wideband Active Balun In Sige Bicmos Technology, Balwant Godara, Alain Fabre
Turkish Journal of Electrical Engineering and Computer Sciences
The aim of this paper is 3-fold: firstly, to provide a comprehensive overview of the use of differential circuits for analogue signal processing in wireless transceivers; secondly, to describe, in detail, single-ended signal to differential conversion, and the corresponding theory of such devices, their characterisation, various methods of implementation, and comparative analyses of their performance; lastly, to propose a new transistor-based solution for wideband baluns. This novel solution is based on the current conveyor and has been modelled using the transistor parameters of a 0.35 \mu m SiGe BiCMOS technology. The salient features of the new implementation are: (a) stable …
Digital Fractional Frequency Synthesizer Based On Counters, Milan Stork
Digital Fractional Frequency Synthesizer Based On Counters, Milan Stork
Turkish Journal of Electrical Engineering and Computer Sciences
This paper describes the architecture of a new pure digital frequency synthesizer based on pulse generators, counters and a register. The technique described here is much simpler than other methods. The synthesizer presented is suitable for the design of VLSI architectures or for programmable large-scale integration circuits.
State-Space Synthesis Of Current-Mode First-Order Log-Domain Filters, Ali̇ Kirçay, Uğur Çam
State-Space Synthesis Of Current-Mode First-Order Log-Domain Filters, Ali̇ Kirçay, Uğur Çam
Turkish Journal of Electrical Engineering and Computer Sciences
This paper proposes current-mode first-order log-domain filters, which are systematically derived using the state-space synthesis procedure. First-order low-pass, high-pass, and all-pass responses are obtained with different circuit types. The filter circuits have very simple structures, since they use only bipolar junction transistors (BJTs) and a grounded capacitor. They can be electronically tuned by changing an external current. The filters have a greater bandwidth due to inherently current-mode and log-domain operation. PSPICE simulations are given to confirm the theoretical analysis.
Statistical Model Of Hot-Carrier Degradation And Lifetime Prediction For P-Mos Transistors, Firat Kaçar, Ayten Kuntman, Hakan Kuntman
Statistical Model Of Hot-Carrier Degradation And Lifetime Prediction For P-Mos Transistors, Firat Kaçar, Ayten Kuntman, Hakan Kuntman
Turkish Journal of Electrical Engineering and Computer Sciences
Along with advances in microelectronics, and computer and space technologies, device dimensions are becoming smaller; as a result, hot-carrier effect, lifetime prediction, and reliability become more important concepts for MOS transistors. In this paper, the degradation in the drain current and threshold voltage of P-MOS transistors are observed by operating the devices under voltage stress conditions. Using the observation results, the effect of hot-carriers was investigated statistically and a new statistical method for modeling was proposed as an alternative to those given in the literature. The linear regression method is used to estimate the power, Weibull, and logarithmic parameters, and …
The Effect Of Collector Doping On Inp-Based Double Heterojunction Bipolar Transistors, Serkan Topaloğlu, Jörn Driesen, Werner Prost, Franz Josef Tegude
The Effect Of Collector Doping On Inp-Based Double Heterojunction Bipolar Transistors, Serkan Topaloğlu, Jörn Driesen, Werner Prost, Franz Josef Tegude
Turkish Journal of Electrical Engineering and Computer Sciences
High current effects on double heterojunction bipolar transistor (DHBT) performance were investigated. Three DHBTs with different collector doping densities were grown and processed. DC and RF measurements were performed to evaluate the influence of collector doping and the related Kirk effect on HBT performance. In addition to these samples, the Kirk effect was proven on SHBTs and the delay of this effect on submicron HBTs was investigated.
Wind Power, Distributed Generation: New Challenges, New Solutions, Vladimiro Miranda
Wind Power, Distributed Generation: New Challenges, New Solutions, Vladimiro Miranda
Turkish Journal of Electrical Engineering and Computer Sciences
This paper discusses some issues related with the growing importance of wind power and in modern power systems and some challenges raised by the emergence of distributed generation, and how computational intelligence and other modern techniques have been able to provide valuable results in solving the new problems. It presents some solutions obtained with a number of computational intelligence techniques and their application to real cases.
Design, Simulation And Tests Of A Low-Cost Microstrip Patch Antenna Arrays For The Wireless Communication, Gonca Çakir, Levent Sevgi̇
Design, Simulation And Tests Of A Low-Cost Microstrip Patch Antenna Arrays For The Wireless Communication, Gonca Çakir, Levent Sevgi̇
Turkish Journal of Electrical Engineering and Computer Sciences
Typical low-cost, low-weight microstrip base station antenna arrays with beam-scanning capabilities are taken into account. In downtowns of large cities like New York, Chicago, and in historical cities like Istanbul, where high buildings are separated by narrow but densely occupied streets, antenna arrays with approximately 20°-35° beam-widths are required to complete the cellular communication coverage. To meet this requirement, new antenna arrays are designed with 35° beam-widths and 60° electronic scanning capabilities. Their characteristics are investigated both numerically and experimentally. An FDTD-based antenna simulation package (M-PATCH) is prepared, tested on canonical structures and against the literature first, for verification and …
Soft Computing Methods In Microwave Active Device Modeling, Yavuz Cengi̇z, Fi̇li̇z Güneş, Mehmet Fati̇h Çağlar
Soft Computing Methods In Microwave Active Device Modeling, Yavuz Cengi̇z, Fi̇li̇z Güneş, Mehmet Fati̇h Çağlar
Turkish Journal of Electrical Engineering and Computer Sciences
In this work, the signal and noise behaviors of a microwave transistor within its operation domain (CT,V_{DS}, I_{DS}, f) are modeled by the Artificial Neural Network (ANN) and Fuzzy Logic System (FLS) without using any information on the microwave circuit theory . A worked example is presented where the same data is employed for both models selected from the manufacturer's data sheets. Performances of the FLS and ANN models are compared and conclusions are drawn.
Fault Tolerant Control With Re-Configuring Sliding-Mode Schemes, Ufuk Demi̇rci̇, Feza Kerestecioğlu
Fault Tolerant Control With Re-Configuring Sliding-Mode Schemes, Ufuk Demi̇rci̇, Feza Kerestecioğlu
Turkish Journal of Electrical Engineering and Computer Sciences
In this paper, a controller design method for linear MIMO systems is presented which a sliding mode controller is reconfigured in case of system faults. Faults are detected with the residual vector generated from a standard linear observer. Once a fault has been detected the fault distribution matrix can be obtained and used to update the corrective or equivalent control parts of the sliding mode controller. As a result, fault tolerant adaptive controllers keep the system performance within acceptable limits or at least avoids the system to wind-up.
Computation Of Association Probabilities For Single Target Tracking With The Use Of Adaptive Neuro-Fuzzy Inference System, İlke Türkmen, Keri̇m Güney
Computation Of Association Probabilities For Single Target Tracking With The Use Of Adaptive Neuro-Fuzzy Inference System, İlke Türkmen, Keri̇m Güney
Turkish Journal of Electrical Engineering and Computer Sciences
In this study, a simple method based on the adaptive neuro-fuzzy inference system (ANFIS) is presented for computing the association probabilities. The computed association probabilities are used to track the single manoeuvring target in the cluttered environment. A hybrid learning algorithm, which combines the least square method and the backpropagation algorithm, is used to identify the parameters of ANFIS. The tracks estimated by using the method proposed in this study are in very good agreement with the true tracks. Better accuracy with respect to the well known nearest neighbour Kalman filter and probabilistic data association algorithms is obtained.
Silhouette Based Human Motion Detection And Analysis For Real-Time Automated Video Surveillance, Murat Eki̇nci̇, Eyüp Gedi̇kli̇
Silhouette Based Human Motion Detection And Analysis For Real-Time Automated Video Surveillance, Murat Eki̇nci̇, Eyüp Gedi̇kli̇
Turkish Journal of Electrical Engineering and Computer Sciences
In this paper, a real-time background modeling and maintenance based human motion detection and analysis in an indoor and an outdoor environments for visual surveillance system is described. The system operates on monocular gray scale video imagery from a static CCD camera. In order to detect foreground objects, first, background scene model is statistically learned using the redundancy of the pixel intensities in a training stage, even the background is not completely stationary. This redundancy information of the each pixel is separately stored in an history map shows how the pixel intensity values changes till now. Then the highest ratio …
Impacts Of Distributed Generators On The Oscillatory Stability Of Interconnected Power Systems, İstemi̇han Genç, Ömer Usta
Impacts Of Distributed Generators On The Oscillatory Stability Of Interconnected Power Systems, İstemi̇han Genç, Ömer Usta
Turkish Journal of Electrical Engineering and Computer Sciences
Integration of distributed generation is continually and gradually affecting the stability of interconnected power systems. In this paper, the impacts of distributed synchronous generators on oscillatory stability are studied. In various parameter sub-spaces of interest, feasibility regions can be calculated to determine the conditions to sustain the stable operation of an interconnected power system. Through computations of the feasibility boundaries corresponding to Hopf bifurcations of electromechanical oscillatory modes, we determine the operating limits for a stable operation of the system under small and continual disturbances such as predictable changes in loading conditions of generators. Thus, with the case studies given …
Implementation Of A New Self-Tuning Fuzzy Pid Controller On Plc, Onur Karasakal, Engi̇n Yeşi̇l, Müjde Güzelkaya, İbrahi̇m Eksi̇n
Implementation Of A New Self-Tuning Fuzzy Pid Controller On Plc, Onur Karasakal, Engi̇n Yeşi̇l, Müjde Güzelkaya, İbrahi̇m Eksi̇n
Turkish Journal of Electrical Engineering and Computer Sciences
In this study, the self-tuning method for fuzzy PID controllers that has been developed in a previous study of the authors is implemented on PLC in order to control some standard processes formed on FEEDBACK PCS 327 Process Control Simulator. In this tuning method, the input scaling factor corresponding to the derivative coefficient and the output scaling factor corresponding to the integral coefficient of the fuzzy PID controller are adjusted using a fuzzy inference mechanism with a new input called ``normalized acceleration''. The results of the implementation have been compared with those of the classical fuzzy PID controller without a …