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Articles 20791 - 20820 of 25644

Full-Text Articles in Computer Engineering

Nonlinear Scattering At Hf: Prospects For Exploitation In Oth Radar Systems, Stuart Anderson Jan 2010

Nonlinear Scattering At Hf: Prospects For Exploitation In Oth Radar Systems, Stuart Anderson

Turkish Journal of Electrical Engineering and Computer Sciences

HF skywave `over-the-horizon' radars experience exceptionally high levels of clutter from the earth's surface as a consequence of their `look-down' propagation geometry. While Doppler processing is effective in separating aircraft echoes from the clutter, thereby enabling detection, the same does not always hold for slow moving targets. In particular, ship echoes occupy the same region of Doppler space as the sea clutter, so the likelihood of target echo obscuration is high. By exploiting the known dependence of the characteristic spectral form of the clutter Doppler spectrum on radar frequency and other parameters, HF radars can maximise the prospects for detectability …

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Radar Cross-Section (Rcs) Analysis Of High Frequency Surface Wave Radar Targets, Gonca Çakir, Levent Sevgi̇ Jan 2010

Radar Cross-Section (Rcs) Analysis Of High Frequency Surface Wave Radar Targets, Gonca Çakir, Levent Sevgi̇

Turkish Journal of Electrical Engineering and Computer Sciences

Realistic high frequency surface wave radar (HFSWR) targets are investigated numerically in terms of electromagnetic wave -- target interactions. Radar cross sections (RCS) of these targets are simulated via both the finite-difference time-domain (FDTD) method and the Method of Moments (MoM). The virtual RCS prediction tool that was introduced in previous work is used for these investigations. The virtual tool automatically creates the discrete FDTD model of the target under investigation and performs the FDTD RCS analysis. It also automatically constructs a MoM wire grid model of the target; therefore, it is also possible to compare FDTD results against the …

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Propagation Modeling And Path Loss Prediction Tools For High Frequency Surface Wave Radars, Gökhan Apaydin, Levent Sevgi̇ Jan 2010

Propagation Modeling And Path Loss Prediction Tools For High Frequency Surface Wave Radars, Gökhan Apaydin, Levent Sevgi̇

Turkish Journal of Electrical Engineering and Computer Sciences

Propagation modeling and simulation approaches for the use of High Frequency Surface Wave Radar (HFSWR) are discussed. HFSWR uses vertically polarized surface waves along multi-mixed paths in the lower HF band (3 MHz - 15 MHz). Various numerical propagators are reviewed with an early analytical model. Split Step Fast Fourier Transformation, finite- difference, and finite-element solutions of the well-known one-way, forward propagation Parabolic Equation (PE) model are presented. MATLAB-based numerical propagation prediction tools based on these models are listed. Tests and comparisons among these analytical and numerical tools are given for some canonical surface wave propagation scenarios. The Millington effect …

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Antenna Systems With Beam Forming And Beam Steering Capabilities For Hf Skywave Radars, Çağatay Uluişik Jan 2010

Antenna Systems With Beam Forming And Beam Steering Capabilities For Hf Skywave Radars, Çağatay Uluişik

Turkish Journal of Electrical Engineering and Computer Sciences

Radiation characteristics of linearly phased, periodic, planar dipole arrays, which can be used as transmitting/receiving antenna systems for HF skywave radars, are investigated. Rectangular, triangular and trapezoidal arrays are proposed in obtaining different beam shapes in the desired directions. Beam steering is achieved by adjusting the inter-element phase increments coherently. The effects of vertical array-tilt with a desired take-off angle (TOA) \alpha are presented by a number of radiation pattern examples. The ground effect is investigated using the image theory by assuming the Earth's surface as perfectly electric conductor (PEC). Radiated fields are obtained using Floquet wave representations plus the …

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New Approach Fpga-Based Implementation Of Discontinuous Svpwm}, Tole Sutikno, Auzani Jidin, Nik Rumzi Nik Idris Jan 2010

New Approach Fpga-Based Implementation Of Discontinuous Svpwm}, Tole Sutikno, Auzani Jidin, Nik Rumzi Nik Idris

Turkish Journal of Electrical Engineering and Computer Sciences

The discontinuous space vector pulse-width modulation (DSVPWM) is a well-known technique offering lower switching losses than continuous SVPWM. At the same, average switching frequency, or a switching frequency 1.5 times higher than utilized in continuous SVPWM, the discontinuous SVPWM results in lower current harmonic distortions than that obtained in continuous SVPWM at high modulation indices. This paper is concerned with the design and realization of new FPGA approach based a 5-segment discontinuous SVPWM operated at 40 kHz switching frequency. It will be shown that the implementation of the discontinuous SVPWM utilized in FPGA, to execute some complex tasks, is simplified …

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Hierarchical Fuzzy Controller Applied To Multi-Input Power System Stabilizer, Ebrahim Rasooli Anarmarzi, Mohammad Reza Feyzi, Mehrdad Tarafdar Hagh Jan 2010

Hierarchical Fuzzy Controller Applied To Multi-Input Power System Stabilizer, Ebrahim Rasooli Anarmarzi, Mohammad Reza Feyzi, Mehrdad Tarafdar Hagh

Turkish Journal of Electrical Engineering and Computer Sciences

This paper proposes the application of a hierarchical fuzzy system (HFS) based on multi-input power system stabilizer (MPSS) in multi-machine environment. The number of rules increases exponentially with the number of variables in a standard fuzzy system. This problem is solved in the proposed HFS method. In this method, the total number of rules increases only linearly with the number of input variables. HFS consists of a number of low-dimensional fuzzy systems in a hierarchical form. In the MPSS, the deviation of reactive power \Delta Q is added to a \Delta P+ \Delta \omega input type Power System Stabilizer (PSS) …

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Washout Filter Based Control For The Hodgkin-Huxley Nerve Cell Dynamics, Reşat Özgür Doruk Jan 2010

Washout Filter Based Control For The Hodgkin-Huxley Nerve Cell Dynamics, Reşat Özgür Doruk

Turkish Journal of Electrical Engineering and Computer Sciences

In this work we present a washout filter based control approach for stabilizing the oscillations in Hodgkin-Huxley type neurons. The oscillations occur due to the bifurcations that arise from the potassium and sodium channel conductance deviations. The MATCONT toolbox software environment was used for analysis of the bifurcation points in conjunction with MATLAB. The simulations of the Hodgkin-Huxley (HH) model at those points are provided to validate the results obtained from the MATCONT software. Then a washout filter is proposed to stabilize the oscillations occur at the Hopf bifurcation points where the external current injection is used to provide the …

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A Robust Method For State Estimation Of Power System With Upfc, Mehrdad Tarafdar Hagh, Mehdi Ahmadi Jirdehi Jan 2010

A Robust Method For State Estimation Of Power System With Upfc, Mehrdad Tarafdar Hagh, Mehdi Ahmadi Jirdehi

Turkish Journal of Electrical Engineering and Computer Sciences

This paper presents a Least Absolute Value (LAV) state estimator for power system using a new method called Recursive Least Squares (RLS). Also, a suitable model is used for state estimation of power system that includes a Unified Power Flow Controller (UPFC). The IEEE 14-bus test system is used to show the validity of the proposed algorithm in estimation of power system states as well as the states of controllable parameters of UPFC.

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A Small Scale Education Experiment Kit With Wind Generator-Pem Electrolyser System And Modelling, Özcan Atlam Jan 2010

A Small Scale Education Experiment Kit With Wind Generator-Pem Electrolyser System And Modelling, Özcan Atlam

Turkish Journal of Electrical Engineering and Computer Sciences

A small scale experiment wind energy kit is prepared in order to introduce renewable energy applications. The kit consists of a wind turbine with horizontal axis, a direct current (dc) motor as generator and variable wind excitation system. Performance characteristics of the wind system are defined for different wind speeds. It is found that at the highest 10 m/s wind excitation, the maximum turbine mechanical power from wind is about 0.30 W at 5.3 V., maximum output power of the generator is about 0.18 W and maximum electrical efficiency is about 7% at 4.27 V., wind turbine power coefficients C_p …

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A Novel Method For Lung Segmentation On Chest Ct Images: Complex-Valued Artificial Neural Network With Complex Wavelet Transform, Murat Ceylan, Yüksel Özbay, Osman Nuri̇ Uçan, Erkan Yildirim Jan 2010

A Novel Method For Lung Segmentation On Chest Ct Images: Complex-Valued Artificial Neural Network With Complex Wavelet Transform, Murat Ceylan, Yüksel Özbay, Osman Nuri̇ Uçan, Erkan Yildirim

Turkish Journal of Electrical Engineering and Computer Sciences

Image segmentation is an important step in many computer vision algorithms. The objective of segmentation is to obtained an optimal region of convergences (ROC). Error in this stage will impact all higher level activities. This paper focuses on a new efficient method denoted as Complex-Valued Artificial Neural Network with Complex Wavelet Transform (CWT-CVANN) for the segmentation of lung region on chest CT images. In this combined architecture is composed of two cascade stages: feature extraction with various levels of complex wavelet transform and segmentation with complex-valued artificial neural network. Here, 32 CT images of 6 female and 26 male patients …

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Programmable Design And Implementation Of A Chaotic System Utilizing Multiple Nonlinear Functions, Recai̇ Kiliç, Fatma Yildirim Dalkiran Jan 2010

Programmable Design And Implementation Of A Chaotic System Utilizing Multiple Nonlinear Functions, Recai̇ Kiliç, Fatma Yildirim Dalkiran

Turkish Journal of Electrical Engineering and Computer Sciences

In addition to exhibiting a rich variety of bifurcation and chaos via tuning parameters, a chaotic system introduced by Sprott can be modeled and realized with a fixed main system block and many different changeable nonlinear function blocks such as piecewise-linear function, cubic function and other trigonometric functions. This system is very suitable for implementing a programmable chaos generator according to its changeable nonlinearity. This paper presents a FPAA (Field Programmable Analog Array)-based programmable implementation of this system. Nonlinear function blocks used in this chaotic system are modeled with FPAA programming and a model is rapidly changed for realizing other …

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Fault Detection And Identification For Voltage Sag State Estimation In Power Systems, Jamal Beiza, Seyed Hossein Hosseinian, Behrooz Vahidi Jan 2010

Fault Detection And Identification For Voltage Sag State Estimation In Power Systems, Jamal Beiza, Seyed Hossein Hosseinian, Behrooz Vahidi

Turkish Journal of Electrical Engineering and Computer Sciences

This paper presents a novel approach for fault detection and identification in order to estimate voltage sag during a fault. One of the best approaches for voltage sag estimation is instantaneous voltage estimation. The approach uses traditional state estimation where redundant measurements are available. The proposed method is used to estimate voltage sag performance during a fault. At the fault duration, the grid topology is changed. In such a case the measurement matrix must be re-determined at the fault duration. The proposed approach is an efficient method for fault detection and identification which is based on residual analysis and topology …

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Active Illumination And Appearance Model For Face Alignment, Muhi̇tti̇n Gökmen, Fati̇h Kahraman, Sune Darkner, Rasmus Larsen Jan 2010

Active Illumination And Appearance Model For Face Alignment, Muhi̇tti̇n Gökmen, Fati̇h Kahraman, Sune Darkner, Rasmus Larsen

Turkish Journal of Electrical Engineering and Computer Sciences

Illumination conditions have an explicit effect on the performance of face recognition systems. In particular, varying the illumination upon the face imposes such complex effects that the identification often fails to provide a stable performance level. In this paper, we propose an approach integrating face identity and illumination models in order to reach acceptable and stable face recognition rates. For this purpose, Active Appearance Model (AAM) and illumination model of faces are combined in order to obtain an illumination invariant face localization. The proposed method is an integrated Active Illumination and Appearance Model (AIA) which combines identity, illumination and shape …

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Robust Feedback Design For Nonlinear Systems: A Survey, Alberto Isidori Jan 2010

Robust Feedback Design For Nonlinear Systems: A Survey, Alberto Isidori

Turkish Journal of Electrical Engineering and Computer Sciences

No abstract provided.

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Sdre Optimal Control Of Drug Administration In Cancer Treatment, Mehmet İti̇k, Meti̇n Uymaz Salamci̇, Stephen Paul Banks Jan 2010

Sdre Optimal Control Of Drug Administration In Cancer Treatment, Mehmet İti̇k, Meti̇n Uymaz Salamci̇, Stephen Paul Banks

Turkish Journal of Electrical Engineering and Computer Sciences

In this study, we apply State Dependent Riccati Equation (SDRE) based optimal control technique to a nonlinear tumor growth model. The model consists of three biological cells which are normal tissue, tumor and immune cells. The effect of chemotherapy treatment is also included in the model. Chemotherapy administration is considered as a control input to the nonlinear cancer dynamics and the amount of administered drug is determined by using SDRE optimal control. The optimal control is applied to the model in order not only to drive the tumor cells to the healthy equilibrium state but also to minimize the amount …

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Formation Control Of Nonholonomic Mobile Robots Using Implicit Polynomials And Elliptic Fourier Descriptors, Yeşi̇m Hümay Esi̇n, Mustafa Ünel Jan 2010

Formation Control Of Nonholonomic Mobile Robots Using Implicit Polynomials And Elliptic Fourier Descriptors, Yeşi̇m Hümay Esi̇n, Mustafa Ünel

Turkish Journal of Electrical Engineering and Computer Sciences

This paper presents a novel method for the formation control of a group of nonholonomic mobile robots using implicit and parametric descriptions of the desired formation shape. The formation control strategy employs implicit polynomial (IP) representations to generate potential fields for achieving the desired formation and the elliptical Fourier descriptors (EFD) to maintain the formation once achieved. Coordination of the robots is modeled by linear springs between each robot and its two nearest neighbors. Advantages of this new method are increased flexibility in the formation shape, scalability to different swarm sizes and easy implementation. The shape formation control is first …

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A Model Based Nonlinear Adaptive Controller For The Passive Bilateral Telerobotic System, Ufuk Özbay, Erkan Zergeroğlu, İlyas Kandemi̇r Jan 2010

A Model Based Nonlinear Adaptive Controller For The Passive Bilateral Telerobotic System, Ufuk Özbay, Erkan Zergeroğlu, İlyas Kandemi̇r

Turkish Journal of Electrical Engineering and Computer Sciences

IIn this paper, we propose a new adaptive controller scheme for the bilateral telerobotic/teleoperation systems. The proposed controller achieves asymptotic tracking despite the parametric uncertainties associated with both master and slave robots while ensuring the passivity of the closed loop system. Extensive simulation studies are presented to illustrate the feasibility and efficiency of the proposed adaptive controller.

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Simultaneous Rotor And Stator Resistance Estimation Of Squirrel Cage Induction Machine With A Single Extended Kalman Filter, Eşref Emre Özsoy, Meti̇n Gökaşan, Ovsanna Seta Estrada Jan 2010

Simultaneous Rotor And Stator Resistance Estimation Of Squirrel Cage Induction Machine With A Single Extended Kalman Filter, Eşref Emre Özsoy, Meti̇n Gökaşan, Ovsanna Seta Estrada

Turkish Journal of Electrical Engineering and Computer Sciences

Accurate knowledge of rotor and stator resistance variations in a squirrel-cage induction motor (SCIM) is crucial for the performance of sensorless control of SCIM over a wide range of speeds. This study seeks to address this issue with a single Extended Kalman Filter (EKF) based solution, which is also known to have accuracy limitations when a high number of parameters/states are estimated with a limited number of inputs. To this aim, different from the author's previous approach in operating several EKFs in an alternating manner (the so-called braided EKF), an 8^{th}-order EKF is implemented in this study to test its …

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Analysis And Estimation Of Motion Transmission Errors Of A Timing Belt Drive, Ergi̇n Kiliç, Meli̇k Dölen, Ahmet Buğra Koku Jan 2010

Analysis And Estimation Of Motion Transmission Errors Of A Timing Belt Drive, Ergi̇n Kiliç, Meli̇k Dölen, Ahmet Buğra Koku

Turkish Journal of Electrical Engineering and Computer Sciences

This paper focuses on viable position estimation schemes for timing belt drives where the position of the carriage (load) is to be determined via reference models receiving input from a position sensor attached to the actuator of the timing belt. A detailed analysis of the transmission error sources is presented, and a number of relevant mathematical models are developed using a priori knowledge of the process. This paper demonstrates that such schemes are very effective when the drive system is not subjected to external loads and operating conditions do not change considerably i.e. ambient temperature, belt tension.

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Precise Position Control Using Shape Memory Alloy Wires, Burcu Dönmez, Bülent Özkan, Fevzi̇ Suat Kadioğlu Jan 2010

Precise Position Control Using Shape Memory Alloy Wires, Burcu Dönmez, Bülent Özkan, Fevzi̇ Suat Kadioğlu

Turkish Journal of Electrical Engineering and Computer Sciences

Shape memory alloys (SMAs) are active metallic ``smart'' materials used as actuators and sensors in high technology smart systems [1]. The term shape memory refers to ability of certain materials to ``remember'' a shape, even after rather severe deformations: once deformed at low temperatures, these materials will stay deformed until heated, whereupon they will return to their original, pre-deformed ``learned'' shape [2]. This property can be used to generate motion and/or force in electromechanical devices and micro-machines. However, the accuracy of SMA actuators is severely limited by their highly nonlinear stimulus-response characteristics. In this work, modeling, simulation, and experimental efforts …

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Design And Evaluation Of A Linear Switched Reluctance Actuator For Positioning Tasks, António Espírito Santo, Rosário Calado, Carlos Cabrita Jan 2010

Design And Evaluation Of A Linear Switched Reluctance Actuator For Positioning Tasks, António Espírito Santo, Rosário Calado, Carlos Cabrita

Turkish Journal of Electrical Engineering and Computer Sciences

This paper presents the development of a new linear switched reluctance actuator and confirms its applicability to perform positioning tasks. After the explanation of the actuator working principle and the presentation of its electromechanical topology, an analysis is accomplished using a finite elements tool. Based on the theoretical results, an experimental prototype that can develop 150 N was constructed. Its behaviour is observed under two different control methods implemented with microcontrollers. Initially, position is controlled applying a single pulse-driving scheme. Meanwhile, significant improvements are obtained with the introduction of a sliding-mode controller, allowing movements with 1 mm of resolution.

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Detection Of Static Eccentricity For Permanent Magnet Synchronous Motors Using The Coherence Analysis, Mehmet Akar, Sezai̇ Taşkin, Şahi̇n Serhat Şeker, İlyas Çankaya Jan 2010

Detection Of Static Eccentricity For Permanent Magnet Synchronous Motors Using The Coherence Analysis, Mehmet Akar, Sezai̇ Taşkin, Şahi̇n Serhat Şeker, İlyas Çankaya

Turkish Journal of Electrical Engineering and Computer Sciences

This paper reports on work to detect the static eccentricity faults for permanent magnet synchronous motor (PMSM) using spectral analysis methods. Measurements are carried out by collecting the stator current and voltage, torque and speed for healthy and faulty cases of the motor. Static eccentricity case is formed by changing the rotor position in the manner of sliding the shaft on a horizontal axis. As a result of the spectral analysis for the motor currents, side band effects appeared at around the fundamental frequency are determined as a most important indicator of the eccentricity. In addition to this determination, the …

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Using Covariates For Improving The Minimum Redundancy Maximum Relevance Feature Selection Method, Olcay Kurşun, Cemal Okan Şakar, Oleg Favorov, Ni̇zametti̇n Aydin, Sadik Fi̇kret Gürgen Jan 2010

Using Covariates For Improving The Minimum Redundancy Maximum Relevance Feature Selection Method, Olcay Kurşun, Cemal Okan Şakar, Oleg Favorov, Ni̇zametti̇n Aydin, Sadik Fi̇kret Gürgen

Turkish Journal of Electrical Engineering and Computer Sciences

Maximizing the joint dependency with a minimum size of variables is generally the main task of feature selection. For obtaining a minimal subset, while trying to maximize the joint dependency with the target variable, the redundancy among selected variables must be reduced to a minimum. In this paper, we propose a method based on recently popular minimum Redundancy-Maximum Relevance} (mRMR) criterion. The experimental results show that instead of feeding the features themselves into mRMR, feeding the covariates improves the feature selection capability and provides more expressive variable subsets.

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Usage Of Spline Interpolation In Catheter-Based Cardiac Mapping, Bülent Yilmaz, Uğur Cunedi̇oğlu, Engi̇n Baysoy Jan 2010

Usage Of Spline Interpolation In Catheter-Based Cardiac Mapping, Bülent Yilmaz, Uğur Cunedi̇oğlu, Engi̇n Baysoy

Turkish Journal of Electrical Engineering and Computer Sciences

Due to their minimal invasiveness catheters are highly preferred in cardiac mapping techniques used in the source localization of rhythm disturbances in the heart. In cardiac mapping, standard steerable catheters and multielectrode basket catheters are the two alternatives for the characterization of the underlying tissue on the inner (endocardium) and outer (epicardium) surfaces of the heart. As with any discrete sampling technique, an important question for catheter-based cardiac mapping is how to determine values at locations from which direct measurements are not available. Interpolation is the most common approach for providing values at unmeasured sites using the available measurements. In …

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Delta-Sigma Subarray Beamforming For Ultrasound Imaging, Hasan Şaki̇r Bi̇lge Jan 2010

Delta-Sigma Subarray Beamforming For Ultrasound Imaging, Hasan Şaki̇r Bi̇lge

Turkish Journal of Electrical Engineering and Computer Sciences

In this study, an ultrasonic digital beamformer based on subarray processing of 1-bit delta-sigma (\Delta \Sigma ) oversampled echo signals is presented. The single-bit oversampling \Delta \Sigma conversion simplifies the coherent processing in beamforming with improved timing accuracy. Subarray processing also aims to simplify the beamforming complexity, where the partial-beam sums (low-resolution beams) are acquired from small subarrays, and then these partial beams are coherently processed for producing high-resolution beams. In the \Delta \Sigma subarray beamforming, the \Delta \Sigma coded echo signals are summed over the subarray channels, and then these partial beam-sums are first \Delta \Sigma demodulated, then processed …

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Design Of Optimal Sampling Times For Pharmacokinetic Trials Via Spline Approximation, Musa Hakan Asyali Jan 2010

Design Of Optimal Sampling Times For Pharmacokinetic Trials Via Spline Approximation, Musa Hakan Asyali

Turkish Journal of Electrical Engineering and Computer Sciences

Understanding and comparison of different drug delivery formulations are based on pharmacokinetic parameters (PKP) such as area under curve, maximum concentration, and time to reach maximum concentration. Accurate estimation of PKP is of critical importance in capturing drug absorption and elimination characteristics and in reaching bioequivalence decisions. Since PKP are estimated from a limited number of samples, the timing of the samples directly influences the accuracy of estimation. Optimization of the sampling times may not only increase the accuracy of PKP estimation, but also reduce the number of samples to be drawn, which in turn lessens the inconvenience to the …

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Optimal Feature Selection For 3d Facial Expression Recognition Using Coarse-To-Fine Classification, Hamit Soyel, Hasan Demirel Jan 2010

Optimal Feature Selection For 3d Facial Expression Recognition Using Coarse-To-Fine Classification, Hamit Soyel, Hasan Demirel

Turkish Journal of Electrical Engineering and Computer Sciences

Automatic facial expression recognition for novel individuals from 3D face data is a challenging task in pattern analysis. This paper describes a feature selection process for pose-invariant 3D facial expression recognition. The process provides a lower dimensional subspace representation, which is optimized to improve the classification accuracy, retrieved from geometrical localization of facial feature points to classify facial expressions. Fisher criterion-based approach is adopted to provide a basis for the optimal selection of features. Two-stage probabilistic neural network architecture is employed as a classifier to recognize the facial expressions. In the first stage, which can be regarded as the coarse …

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Fast Computation Of Determination Of The Prime Implicants By A Novel Near Minimum Minimization Method, Fati̇h Başçi̇ftçi̇, Şi̇rzat Kahramanli Jan 2010

Fast Computation Of Determination Of The Prime Implicants By A Novel Near Minimum Minimization Method, Fati̇h Başçi̇ftçi̇, Şi̇rzat Kahramanli

Turkish Journal of Electrical Engineering and Computer Sciences

In this study proposed is an off-set-based direct-cover near-minimum minimization method for single-output Boolean functions represented in a sum-of-products form. To obtain the complete set of prime implicants including given on-cube (on-minterm), the proposed method uses off-cubes (off-minterms) expanded by this On-cube. The amount of temporary results produced by this method does not exceed the size of the off-set. To make fast computation, we used logic operations instead of standard operations. Expansion off-cubes, commutative absorption operations and intersection operations are realized by logic operations for fast computation. The proposed minimization method is tested on several different kinds of problems and …

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A Second Order Approximation To Reduce The Complexity Of Ldpc Decoders Based On Gallager's Approach, Aykut Kalaycioğlu, Oktay Üreten, H. Gökhan İlk Jan 2010

A Second Order Approximation To Reduce The Complexity Of Ldpc Decoders Based On Gallager's Approach, Aykut Kalaycioğlu, Oktay Üreten, H. Gökhan İlk

Turkish Journal of Electrical Engineering and Computer Sciences

A piece-wise second order approximation to the f (x) = -log [tanh (x/2)] function is proposed to reduce the computational complexity of LDPC decoder's utilizing Log-Likelihood Ratio Belief Propagation (LLR-BP) algorithm based on Gallager's approach. Simulation results show that the proposed low complexity approximation doesn't cause BER performance degradation.

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Performance Analysis Of Swarm Optimization Approaches For The Generalized Assignment Problem In Multi-Target Tracking Applications, Ali̇ Önder Bozdoğan, Asim Egemen Yilmaz, Murat Efe Jan 2010

Performance Analysis Of Swarm Optimization Approaches For The Generalized Assignment Problem In Multi-Target Tracking Applications, Ali̇ Önder Bozdoğan, Asim Egemen Yilmaz, Murat Efe

Turkish Journal of Electrical Engineering and Computer Sciences

The aim of this study is to investigate the suitability of selected swarm optimization algorithms to the generalized assignment problem as encountered in multi-target tracking applications. For this purpose, we have tested variants of particle swarm optimization and ant colony optimization algorithms to solve the 2D generalized assignment problem with simulated dense and sparse measurement/track matrices and compared their performance to that of the auction algorithm. We observed that, although with some modification swarm optimization algorithms provide improvement in terms of speed, they still fall behind the auction algorithm in finding the optimum solution to the problem. Among the investigated …

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