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Articles 3061 - 3090 of 3106
Full-Text Articles in Computer Engineering
Meta-Genetic Programming: Co-Evolving The Operators Of Variation, Bruce Edmonds
Meta-Genetic Programming: Co-Evolving The Operators Of Variation, Bruce Edmonds
Turkish Journal of Electrical Engineering and Computer Sciences
The standard Genetic Programming approach is augmented by co-evolving the genetic operators. To do this the operators are coded as trees of indefinite length. In order for this technique to work, the language that the operators are defined in must be such that it preserves the variation in the base population. This technique can varied by adding further populations of operators and changing which populations act as operators for others, including itself, thus to provide a framework for a whole set of augmented GP techniques. The technique is tested on the parity problem. The pros and cons of the technique …
All-Optical Networking, Altan Koçyi̇ği̇t, Demeter Gökişik, Semi̇h Bi̇lgen
All-Optical Networking, Altan Koçyi̇ği̇t, Demeter Gökişik, Semi̇h Bi̇lgen
Turkish Journal of Electrical Engineering and Computer Sciences
A survey of recent literature on all optical networking is presented. Starting from multiplexing techniques and topological features, network design and performance issues are reviewed. Particular attention is devoted to Wavelength Division Multiplexing (WDM) networks. Static and dynamic solutions of the routing and wavelength assignment (RWA) problem are considered. Issues of current research are summarized.
An Integrated Design-Object Modeling Environment -- Pluggable Metamodel Mechanism --, Masaharu Yoshioka, Takayuki Sekiya, Tetsuo Tomiyama
An Integrated Design-Object Modeling Environment -- Pluggable Metamodel Mechanism --, Masaharu Yoshioka, Takayuki Sekiya, Tetsuo Tomiyama
Turkish Journal of Electrical Engineering and Computer Sciences
We propose a new integrated computational environment to support design object modeling, during engineering design process that requires a variety of design object models, such as a geometric model, a control model, and a finite element model. To integrate multiple design object models, we have developed a mechanism called a metamodel mechanism that maintains consistency among various models. The metamodel mechanism represents relationships among concepts used in these models and is useful, for example, to conduct concurrent engineering practices. In this framework, we formalize a design process as operations to the metamodel. This paper expands the concept of the metamodel …
Combining Multiple Representations For Pen-Based Handwritten Digit Recognition, Fevzi̇ Ali̇moğlu, Ethem Alpaydin
Combining Multiple Representations For Pen-Based Handwritten Digit Recognition, Fevzi̇ Ali̇moğlu, Ethem Alpaydin
Turkish Journal of Electrical Engineering and Computer Sciences
We investigate techniques to combine multiple representations of a handwritten digit to increase classification accuracy without significantly increasing system complexity or recognition time. In pen-based recognition, the input is the dynamic movement of the pentip over the pressure sensitive tablet. There is also the image formed as a result of this movement. On a real-world database of handwritten digits containing more than 11,000 handwritten digits, we notice that the two multi-layer perceptron (MLP) based classifiers using these representations make errors on different patterns implying that a suitable combination of the two would lead to higher accuracy. We implement and compare …
Fuzzy Modeling Approach For Integrated Assessments Using Cultural Theory, Adnan Yazici, Fred E. Petry, Curt Pendergraft
Fuzzy Modeling Approach For Integrated Assessments Using Cultural Theory, Adnan Yazici, Fred E. Petry, Curt Pendergraft
Turkish Journal of Electrical Engineering and Computer Sciences
It has already been noted that the accurate prediction of societal responses requires the use of a formal model based on some social or cultural taxonomy. One such taxonomic candidate is Cultural Theory (CT). CT argues that all societies, irrespective of time or place, are informed by their underlying worldviews, which must be more or less Hierarchic, more or less Individualistic, more or less Egalitarian, and more or less Fatalistic. This approach appears to have a potential for cross-temporal and spatial comparisons that makes it a particularly attractive instrument for a study of the human dimensions of global climate change. …
Advances In Computer And Information Sciences: From Abacus To Holonic Agents, Tuncer Ören
Advances In Computer And Information Sciences: From Abacus To Holonic Agents, Tuncer Ören
Turkish Journal of Electrical Engineering and Computer Sciences
The shift of paradigm emphasizing the importance of the ability to process knowledge rather then being knowledgeable is stressed. A taxonomy of knowledge processing tools, machines, or systems is offered. Major possibilities for future achievements that the author would like to underline are listed with emphasis on agent technology, agent-directed simulation, holonic agents, holonic-agent simulation, and contribution of system theories for cognitive abilities such as understanding, learning, adaptation, and anticipation in computerization.
Bag Distributed Real-Time Operating System And Task Migration, Beki̇r Tevfi̇k Akgün
Bag Distributed Real-Time Operating System And Task Migration, Beki̇r Tevfi̇k Akgün
Turkish Journal of Electrical Engineering and Computer Sciences
BAG is a distributed operating system designed for real-time applications which is run on a distributed real-time system. The heterogeneously distributed BAG system consists of nodes which have VME-bus chassis, different types of processor modules, and an interconnection network. The operating system has three main parts having distributed properties: task migration, load balancing and a distributed file system. Heterogeneous task migration is based on the extended finite state machine (EFSM) programming model. The EFMS model has also eased the implementation of the migration mechanism. The load balancing algorithm is centralized in one node. But the overall system will be a …
Avalanche And Bit Independence Properties For The Ensembles Of Randomly Chosen N \Times N S-Boxes, Işil Vergi̇li̇, Melek D. Yücel
Avalanche And Bit Independence Properties For The Ensembles Of Randomly Chosen N \Times N S-Boxes, Işil Vergi̇li̇, Melek D. Yücel
Turkish Journal of Electrical Engineering and Computer Sciences
Cryptographic test methods such as avalanche, strict avalanche and bit independence criteria, which measure the degree of security of the s-boxes of substitution-permutation networks, are applied to randomly generated ensembles of ( n \times n \) s-boxes. Statistical analysis of experimental data directs the work towards defining ``relative errors'' and examining the avalanche and strict avalanche criteria within ``relative error ranges''. Histograms of relative errors in each ensemble are evaluated, and combining the results of different ensembles corresponding to different values of the s-box size, variations of maximum relative errors versus the size of the s-box are depicted. Some predictions …
Accurate Parameter Estimation For An Articulatory Speech Synthesizer With An Improved Neural Network Mapping, Hali̇s Altun, Tankut Yalçinöz, K. Mervyn Curtis
Accurate Parameter Estimation For An Articulatory Speech Synthesizer With An Improved Neural Network Mapping, Hali̇s Altun, Tankut Yalçinöz, K. Mervyn Curtis
Turkish Journal of Electrical Engineering and Computer Sciences
Neural network (NN) applications have recently been employed to extract the parameters of an articulatory speech synthesizer from a given speech signal. Results from these attempts showed that a single NN is insufficient to cover all of the possible configurations uniquely. Moreover, apart from their computational advantages, NN mapping is so far not superior to the other mapping techniques [1]. Thus there is a clear need to improve NN solution to the inverse problem. Results from our earlier experiments with an articulatory speech synthesizer have shown that the statistical characteristic of the articulatory target pattern vectors can be exploited for …
Performance Evaluation Of Safer K-64 And S-Boxes Of The Safer Family, Ekrem Aras, Melek D. Yücel
Performance Evaluation Of Safer K-64 And S-Boxes Of The Safer Family, Ekrem Aras, Melek D. Yücel
Turkish Journal of Electrical Engineering and Computer Sciences
If the characteristics of s-boxes of the SAFER family of ciphers are examined for the criteria of strict avalanche, bit independence, and XOR table distribution, experiments show that the ``exponentiating'' s-box has a weakness for an input difference of 128 (=10000000_{2}) and the ``logarithm-taking'' s-box has a weakness for an input difference of 253 (=11111101_{2}). However, since these experiments are performed by isolating the s-boxes from the general structure, they do not necessarily indicate a weakness in the overall algorithm. We propose a quick and rough test method, called the avalanche weight distribution criterion, to evaluate the overall performance of …
A More Efficient Design And Implementation Of Cal Programs In Natural Science Using Object-Oriented Technology, Jurgen Friedrich
A More Efficient Design And Implementation Of Cal Programs In Natural Science Using Object-Oriented Technology, Jurgen Friedrich
Turkish Journal of Electrical Engineering and Computer Sciences
With the amount and complexity of science topics and applications increasing, the need for appropriate and effective science education is constantly growing. Computer-based education is very promising to help both teachers and learners in their difficult task, which involves complex psychological processes. This complexity is reflected in high demands on the design and implementation methods used to create computer-assisted learning (CAL) programs. Due to their concepts, flexibility, maintainability and extended library resources, object-oriented technology (OOT) is very suitable to producing this type of pedagogical tool. The introduced approach is demonstrated by a basketball simulation program for instruction in Newtonian mechanics …
Ota-C Based Proportional-Integral-Derivative (Pid) Controller And Calculating Optimum Parameter Tolerances, Cevat Erdal, Ali̇ Toker, Cevdet Acar
Ota-C Based Proportional-Integral-Derivative (Pid) Controller And Calculating Optimum Parameter Tolerances, Cevat Erdal, Ali̇ Toker, Cevdet Acar
Turkish Journal of Electrical Engineering and Computer Sciences
Proportional-integral-derivative (PID) controllers are one of the most important control elements used in the process control industry. In practice, operational amplifiers are generally used in analog controllers. On the other hand, the operational transconductance amplifiers recently developed, which have some positive properties compared to operational amplifiers, are not used in analog controller design at present. Furthermore, the optimum parameter tolerances for the proposed PID circuit by the use of parameter sensitivities are determined. These tolerances keep the relative error at the output of the controller due to parameter variations in the tolerance region.
Scalar Wave Diffraction By A Perfectly Soft Infinitely Thin Circular Ring, Fati̇h Di̇kmen, Ertuğrul Karaçuha, Yury Alexanderovich Tuchkin
Scalar Wave Diffraction By A Perfectly Soft Infinitely Thin Circular Ring, Fati̇h Di̇kmen, Ertuğrul Karaçuha, Yury Alexanderovich Tuchkin
Turkish Journal of Electrical Engineering and Computer Sciences
A new strong mathematically rigorous and numerically effective method for solving the boundary value problem of scalar (for example acoustic) wave diffraction by a perfectly soft (Dirichlet boundary condition) infinitely thin circular ring is proposed. The method is based on the combination of the Orthogonal Polynomials Approach, and on the ideas of the methods of analytical regularization. As a result of the suggested regularization procedure, the initial boundary value problem is equivalently reduced to the infinite system of the linear algebraic equations of the second kind, i.e., to an equation of the type ( (I + H) x = b …
Knowledge-Based Navigation For Autonomous Road Vehicles, Murat Eki̇nci̇, Franches W.J.Gibbs, Barry T. Thomas
Knowledge-Based Navigation For Autonomous Road Vehicles, Murat Eki̇nci̇, Franches W.J.Gibbs, Barry T. Thomas
Turkish Journal of Electrical Engineering and Computer Sciences
This paper presents a computer vision system for an autonomous road vehicle (ARV) that is capable of negotiating complex road networks including road junctions in real time. The ultimate aim of the system is to enable the vehicle to drive automatically along a given complex road network whose geometric description is known. This computer vision system includes three main techniques which are necessary for an ARV: a) road following, b) road junction detection, c) manoeuvring at the road junction. The road following algorithm presents a method of executing a number of algorithms using different methods concurrently, fusing their outputs together …
An Efficient Algorithm To Determine The Periodic Steady-State Solutions Of Nonlinear Systems Using Extended Spectral Analysis, Gülay Tohumoğlu
An Efficient Algorithm To Determine The Periodic Steady-State Solutions Of Nonlinear Systems Using Extended Spectral Analysis, Gülay Tohumoğlu
Turkish Journal of Electrical Engineering and Computer Sciences
A new method for the solution of nonlinear periodic systems was developed. It avoids the time domain calculations of the whole network equations. In the proposed method, by forming the augmented network as linear and nonlinear subnetworks these subnetworks are formulated in complex frequency and time domain respectively. Using spectral analysis the steady-state periodic solution of the whole nonlinear network is reached by an iterative approach. The method can be applied efficiently to weak and strong nonlinear circuits equally well. When we divide the network into a large linear subnetwork and a small nonlinear subnetwork, this method can be applied …
Decentralised H_{\Infty} Load Frequency Controller Design Based On Ssvs, Hasan Çi̇men
Decentralised H_{\Infty} Load Frequency Controller Design Based On Ssvs, Hasan Çi̇men
Turkish Journal of Electrical Engineering and Computer Sciences
The decentralised load-frequency controller design problem concerned is translated into an equivalent problem of decentralised controller design for a multi-area multi-input multi-output (MIMO) control system. It is shown that subject to a condition based on the structured singular values (SSVs), each local area load-frequency controller can be designed independently. The stability condition for the overall system can be stated as to achieve a sufficient interaction margin. It is demonstrated by computer simulation that within this general framework, local H$_{\infty}$ controllers can be designed to achieve satisfactory performances for a sample two-area power system.
Information And Average Information Rates Of A Graphical Access Structure On Six Vertices, Mustafa Atici
Information And Average Information Rates Of A Graphical Access Structure On Six Vertices, Mustafa Atici
Turkish Journal of Electrical Engineering and Computer Sciences
In this paper we study the optimal information and average information rates of secret sharing schemes which are all connected graphs on six vertices. There are $102$ connected graphs on six vertices that are not complete multipartite graphs. Of these $102$ graphs, we determined the optimal information rate of $71$ graphs, and the optimal average information rate of $88$ graphs.
Comparison Of Simulation Algorithms For The Hopfield Neural Network: An Application Of Economic Dispatch, Tankut Yalçinöz, Hali̇s Altun
Comparison Of Simulation Algorithms For The Hopfield Neural Network: An Application Of Economic Dispatch, Tankut Yalçinöz, Hali̇s Altun
Turkish Journal of Electrical Engineering and Computer Sciences
This paper is mainly concerned with an investigation of the suitability of Hopfield neural network structures in solving the power economic dispatch problem. For Hopfield neural network applications to this problem three important questions have been answered: what the size of the power system is; how efficient the computational method; and how to handle constraints. A new mapping process is formulated and a computational method for obtaining the weights and biases is described. A few simulation algorithms used to solve the dynamic equation of the Hopfield neural network are discussed. The results are compared with those of a classical technique, …
Radiation From An Impedance Loaded Parallel-Plate Waveguide, Fi̇li̇z Bi̇rbi̇r, Ali̇nur Büyükaksoy
Radiation From An Impedance Loaded Parallel-Plate Waveguide, Fi̇li̇z Bi̇rbi̇r, Ali̇nur Büyükaksoy
Turkish Journal of Electrical Engineering and Computer Sciences
A hybrid method consisting of employing the mode matching method in conjunction with the Fourier transform technique is used to analyze the radiation of the dominant TEM-wave from an impedance loaded parallel-plate waveguide. The hybrid method that we adopt here reduces the related boundary value problem to a scalar modified Wiener-Hopf equation of the second kind. The solution involves infinitely many unknown constants satisfying an infinite system of linear algebraic equations susceptible to a numerical treatment. Some computational results illustrating the effects of various parameters on the radiation phenomenon are also presented.
A Pseudo Spot Price Algorithm Applied To The Pumped-Storage Hydraulic Unit Scheduling Problem, Sali̇h Fadil, Celal Yaşar
A Pseudo Spot Price Algorithm Applied To The Pumped-Storage Hydraulic Unit Scheduling Problem, Sali̇h Fadil, Celal Yaşar
Turkish Journal of Electrical Engineering and Computer Sciences
A lossy electric power system that contains thermal units and a pumped-storage hydraulic unit is considered in this paper. The total cost of thermal units in an operation cycle is minimized under some possible electric and hydraulic constraints of the units. The operation cycle is divided into time intervals where the system loads are assumed to remain constant. The proposed solution technique has two main parts. In the first part, the active thermal generations and active generation or pumping power of the pumped-storage unit in all time intervals are determined by using units' active generation incremental costs and pseudo spot …
Distance Spectra For Trellis Coded Modulation Schemes On Channels With Intersymbol Interference, Sabi̇re Haciömeroğlu, Melek D. Yücel
Distance Spectra For Trellis Coded Modulation Schemes On Channels With Intersymbol Interference, Sabi̇re Haciömeroğlu, Melek D. Yücel
Turkish Journal of Electrical Engineering and Computer Sciences
The effect of intersymbol interference on distance spectra for trellis coded 8-PSK, 16-QAM and 32-AMPM modulation schemes is evaluated using the methods proposed by Schlegel. Distance spectra of 16-state 8-PSK scheme are computed for different intersymbol interference channels. It is seen that on channels with intersymbol interference the spectral lines are spread into a nearly continuous spectrum and the minimum Euclidean distance between codewords decreases severely. Hence, although the main contribution at large signal to noise ratios comes from the minimum Euclidean distance ( d_{free} ) , higher spectral components also become very important at moderate values of the signal …
A Fuzzy Identification Method For Nonlinear Systems, İbrahi̇m Eksi̇n, Osman Kaan Erol
A Fuzzy Identification Method For Nonlinear Systems, İbrahi̇m Eksi̇n, Osman Kaan Erol
Turkish Journal of Electrical Engineering and Computer Sciences
In this paper, two mathematical ways of building a fuzzy model of both linear and nonlinear systems are presented and compared. In order to determine a model for a nonlinear system, the phase plane is divided into sub-regions and a linear model is assigned for each of these regions. This linear model is represented either in state-space or ARX model form. To determine the pre-selected parameters of the linear system model under study, least-square identification method is used. Then these linear models are arranged in a fuzzy manner to characterize the overall system behavior. The results show that this method …
Control Chart Pattern Recognition Using Artificial Neural Networks, Şeref Sağiroğlu, Erkan Beşdok, Mehmet Erler
Control Chart Pattern Recognition Using Artificial Neural Networks, Şeref Sağiroğlu, Erkan Beşdok, Mehmet Erler
Turkish Journal of Electrical Engineering and Computer Sciences
Precise and fast control chart pattern (CCP) recognition is important for monitoring process environments to achieve appropriate control and to produce high quality products. CCPs can exhibit six types of pattern: normal, cyclic, increasing trend, decreasing trend, upward shift and downward shift. Except for normal patterns, all other patterns indicate that the process being monitored is not functioning correctly and requires adjustment. This paper describes a new type of neural network for speeding up the training process and to compare three training algorithms in terms of speed, performance and parameter complexity for CCP recognition. The networks are multilayered perceptrons trained …
Differentiating Type Of Muscle Movement Via Ar Modeling And Neural Network Classification, Beki̇r Karlik
Differentiating Type Of Muscle Movement Via Ar Modeling And Neural Network Classification, Beki̇r Karlik
Turkish Journal of Electrical Engineering and Computer Sciences
The aim of this study is to classify electromyogram (EMG) signals for controlling multifunction proshetic devices. An artificial neural network (ANN) implementation was used for this purpose. Autoregressive (AR) parameters of $a_1, a_2, a_3, a_4$ and their signal power obtained from different arm muscle motions were applied to the input of ANN, which is a multilayer perceptron. At the output layer, for 5000 iterations, six movements were distinguished at a high accuracy of 97.6%.
Effects Of Parasitic Elements On Oscillation Frequency Of Ota-C Sinusoidal Oscillators, Ari̇f Nacaroğlu, Ergun Erçelebi̇
Effects Of Parasitic Elements On Oscillation Frequency Of Ota-C Sinusoidal Oscillators, Ari̇f Nacaroğlu, Ergun Erçelebi̇
Turkish Journal of Electrical Engineering and Computer Sciences
An oscillator circuit which incorporates Operational Transconductance Amplifiers is presented. The circuit is designed using three OTAs and two grounded capacitors. The frequency of oscillation is tunable over a wide frequency range. The effects of the parasitic elements on the oscillation frequency and the oscillation condition are studied. The theoretical results are compared with the experimental results for a practical oscillator circuit.
On The Global Stabilization Of Nonlinear Systems Via Switching Manifolds, Stephen P. Banks, Meti̇n U. Salamci, M. Kemal Özgören
On The Global Stabilization Of Nonlinear Systems Via Switching Manifolds, Stephen P. Banks, Meti̇n U. Salamci, M. Kemal Özgören
Turkish Journal of Electrical Engineering and Computer Sciences
The global stabilization of nonlinear systems is investigated by using switching surfaces. The nonlinear system is forced to a lower order switching manifold, which is designed to be stable by construction. Thus, the stability of the reduced-order system is guaranteed and parameter selection for the switching surface is avoided. The method is extended to a class of uncertain nonlinear systems and exemplified with some fictitious dynamic models.
A Simple Formula Obtained Using Tabu Search Algorithm For The Radiation Efficiency Of A Resonant Rectangular Microstrip Antenna, Dervi̇ş Karaboğa, Keri̇m Güney
A Simple Formula Obtained Using Tabu Search Algorithm For The Radiation Efficiency Of A Resonant Rectangular Microstrip Antenna, Dervi̇ş Karaboğa, Keri̇m Güney
Turkish Journal of Electrical Engineering and Computer Sciences
A new simple formula for the radiation efficiency of a resonant rectangular microstrip patch antenna is presented. The formula is obtained by using a tabu search algorithm, which is a quite new optimization technique based on the principles of intelligent problem solving. The formula is valid for substrates with relative permittivities between 1 and 12.8 and for the complete range of thicknesses normally used. The results obtained by using this new simple formula are in conformity with those reported elsewhere. The formula can also be used in the calculation of the radiation efficiency of dipoles.
Exclusive Disjunctions In Indefinite And Maybe Information In Relational Databases, Taflan İ. Gündem
Exclusive Disjunctions In Indefinite And Maybe Information In Relational Databases, Taflan İ. Gündem
Turkish Journal of Electrical Engineering and Computer Sciences
Incorporating indefinite information into databases has been studied extensively. In this paper, we propose a structure called an E-table to represent maybe information and inclusive and exclusive disjunctions. We define the type of redundancies in E-tables and show how to eliminate them. Also we present an extended relational algebra to operate on E-tables. In this paper we expand the concepts and operations defined by Lin and Sunderraman [1] in order to accommodate exclusive disjunctions in relational databases.
Functional Radionuclide Imaging Algorithm Based On The Appended Curve Deconvolution Technique And Its Use In The Diagnosis Of Renovascular Hypertension, İrfan Karagöz, Hi̇kmet Bayhan
Functional Radionuclide Imaging Algorithm Based On The Appended Curve Deconvolution Technique And Its Use In The Diagnosis Of Renovascular Hypertension, İrfan Karagöz, Hi̇kmet Bayhan
Turkish Journal of Electrical Engineering and Computer Sciences
In this study, a new method called the pixel basis functional radionuclide imaging (PBFRI) algorithm based on the appended curve deconvolution technique, in order to be able to increase the medical diagnostic capability of a conventional gamma camera, is presented together with the clinical results. In the PBFRI method, retention function of each pixel is obtained from the renograms and cardiac curves generated by processing the filtered segments of the kidney and heart, using a special deconvolution method. The deconvolution operation is done by using the Fourier transform technique. High frequency artifacts presented by the Fourier transform are removed by …
Genetic Approach For The Determination Of Object Parameters From X Ray Projections, Tayfun Günel, Sedef Kent
Genetic Approach For The Determination Of Object Parameters From X Ray Projections, Tayfun Günel, Sedef Kent
Turkish Journal of Electrical Engineering and Computer Sciences
In this study, a new method is presented, based on genetic algorithms for determining object parameters such as radii and/or attenuation coefficients with some assumptions and estimating a cross-sectional image of an object from its projections obtained by X ray illumination. After it was tested for projections degraded by different random noise levels, it was observed that the genetic and fuzzy genetic algorithms improved the signal to noise ratio of the projections. The fuzzy genetic algorithm gave better results than the genetic algorithm.