Open Access. Powered by Scholars. Published by Universities.®

Engineering Commons™

Open Access. Powered by Scholars. Published by Universities.®

Computer Engineering

Institution
Keyword
Publication Year
Publication
Publication Type
File Type

Articles 22771 - 22800 of 25652

Full-Text Articles in Engineering

Modeling And Simulation Concepts In Engineering Education: Virtual Tools, Levent Sevgi̇ Jan 2006

Modeling And Simulation Concepts In Engineering Education: Virtual Tools, Levent Sevgi̇

Turkish Journal of Electrical Engineering and Computer Sciences

This article reviews fundamental concepts of modeling and simulation in computational sciences, such as a model, analytical- and numerical-based modeling, simulation, validation, verification, etc., in relation to the virtual labs widely-offered as parts of engineering education. Virtual tools that can be used in electromagnetic engineering are also introduced.

Go to article

A Labview-Based Virtual Instrument For Engineering Education: A Numerical Fourier Transform Tool, Levent Sevgi̇, Çağatay Uluişik Jan 2006

A Labview-Based Virtual Instrument For Engineering Education: A Numerical Fourier Transform Tool, Levent Sevgi̇, Çağatay Uluişik

Turkish Journal of Electrical Engineering and Computer Sciences

Engineering is based on practice. The minima of this practice should be given during the university education. This has become more and more comprehensive and expensive parallel to high-technology devices developed and presented to societies. Computers, microprocessor-based devices, programmable systems on Chip (PSoC), etc., make engineering education not only very complex but interdisciplinary as well. Building undergraduate labs has become more and more expensive if only physical experimentation and hands-on training are targeted. On the other hand, simple, comparatively much cheaper software may turn a regular personal computer (PC) into a virtual lab. The key question therefore is, to establish …

Go to article

Two, Three And Four-Dimensional Electromagnetics Using Differential Forms, Karl F. Warnick, Peter Russer Jan 2006

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 …

Go to article

Complex Analysis Of The Lossy-Transmission Line Theory: A Generalized Smith Chart, E. Gago-Ribas, C. Dehesa-Martinez, M. J. Gonzalez-Morales Jan 2006

Complex Analysis Of The Lossy-Transmission Line Theory: A Generalized Smith Chart, E. Gago-Ribas, C. Dehesa-Martinez, M. J. Gonzalez-Morales

Turkish Journal of Electrical Engineering and Computer Sciences

It has been very usual in the specialized literature to skip the detailed study of the lossy transmission line theory by reducing it to the low-loss approximation. Although this is valid in the most common practical cases, the study of the general lossy case becomes very important due to the fact that it makes possible a better and deeper understanding of the physical effects associated to general losses, as well as the low-loss frequency-dependent regime. Besides, the analysis of the general case provides important results that may be extended to the analysis of real waveguiding systems, facilitating the understanding and …

Go to article

Speech Pre-Processing For Pitch And Pitch-Cylce Evolutions Smoothing, Hassan Farsi Jan 2006

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 …

Go to article

Human Identification Using Gait, Murat Eki̇nci̇ Jan 2006

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 …

Go to article

Adaptive 3d Visual Servo Control Of Robot Manipulators Via Composite Camera Inputs, Türker Şahi̇n, Erkan Zergeroğlu Jan 2006

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 …

Go to article

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 Jan 2006

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.

Go to article

Agents For Integrating Distributed Data For Complex Computations, Ahmed M. Khedr, Raj Bhatnagar Jan 2006

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 …

Go to article

State Of The Art For Differential Circuits In Wireless Transceivers: A New Wideband Active Balun In Sige Bicmos Technology, Balwant Godara, Alain Fabre Jan 2006

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 …

Go to article

Digital Fractional Frequency Synthesizer Based On Counters, Milan Stork Jan 2006

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.

Go to article

Statistical Model Of Hot-Carrier Degradation And Lifetime Prediction For P-Mos Transistors, Firat Kaçar, Ayten Kuntman, Hakan Kuntman Jan 2006

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 …

Go to article

The Effect Of Collector Doping On Inp-Based Double Heterojunction Bipolar Transistors, Serkan Topaloğlu, Jörn Driesen, Werner Prost, Franz Josef Tegude Jan 2006

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.

Go to article

An Adaptive Feedforward Amplifier Application For 5.8 Ghz, Engi̇n Kurt, Osman Palamutçuoğullari Jan 2006

An Adaptive Feedforward Amplifier Application For 5.8 Ghz, Engi̇n Kurt, Osman Palamutçuoğullari

Turkish Journal of Electrical Engineering and Computer Sciences

In this study, a 5.8 GHz power amplifier is linearized by an adaptive feedforward technique. A DSP-based control scheme is applied to reduce the intermodulation distortion of this amplifier. A two-tone test is used to verify the design.

Go to article

Artificial Neural Design Of Microstrip Antennas, Nurhan Türker, Fi̇li̇z Güneş, Tülay Yildirim Jan 2006

Artificial Neural Design Of Microstrip Antennas, Nurhan Türker, Fi̇li̇z Güneş, Tülay Yildirim

Turkish Journal of Electrical Engineering and Computer Sciences

A general design procedure is suggested for microstrip antennas using artificial neural networks and this is demonstrated using rectangular patch geometry. In this design procedure, synthesis is defined as the forward side and then analysis as the reverse side of the problem. Worked examples are given using the most efficient materials.

Go to article

Wind Power, Distributed Generation: New Challenges, New Solutions, Vladimiro Miranda Jan 2006

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.

Go to article

Controlling Rail Potential Of Dc Supplied Rail Traction Systems, Mehmet Turan Söylemez, Süleyman Açikbaş, Adnan Kaypmaz Jan 2006

Controlling Rail Potential Of Dc Supplied Rail Traction Systems, Mehmet Turan Söylemez, Süleyman Açikbaş, Adnan Kaypmaz

Turkish Journal of Electrical Engineering and Computer Sciences

Most modern DC electrified mass transit systems use a totally floating earth as their grounding strategy. A well-known problem related with totally floating systems is that the touch potentials can be dangerously high. In order to reduce the voltages on rails, several devices exist. Most of these devices allow a direct connection to earth when a certain voltage threshold is exceeded. In this paper, the working principles of these devices are given and the effect of certain parameters related with these devices on the minimum achievable touch potentials is investigated.

Go to article

Perceptually Meaningful Image Editing: Depth, Reynold J. Bailey, Cindy Grimm Jan 2006

Perceptually Meaningful Image Editing: Depth, Reynold J. Bailey, Cindy Grimm

All Computer Science and Engineering Research

We introduce the concept of perceptually meaningful image editing and present two techniques for manipulating the apparent depth of objects in an image. The user loads an image, selects an object and specifies whether the object should appear closer or further away. The system automatically determines target values for the object and/or background that achieve the desired depth change. These depth editing operations, based on techniques used by traditional artists, manipulate either the luminance or color temperature of different regions of the image. By performing blending in the gradient domain and reconstruction with a Poisson solver, the appearance of false …

Go to article

Design Of A Diversified Network Substrate, Jonathan Turner Jan 2006

Design Of A Diversified Network Substrate, Jonathan Turner

All Computer Science and Engineering Research

A diversified network substrate enables multiple end-to-end metanetworks to co-exist within a shared physical infrastructure. Metanetworks are implemented by metarouters, hosted by substrate routers, and metarouters are connected by metalinks. The substrate allocates resources (both link bandwidth and processing resources) to metarouters based on advance reservations received from metanetwork planning systems. It also enables dynamic creation of access metalinks, connecting end systems to metarouters, and supports mobility of end systems under the control of their metanetworks. This report defines a model for a diversified internet and presents a detailed design of the substrate that enables metanetworks to co-exist. The design …

Go to article

Mobiwork: Mobile Workflow For Manets, Gregory Hackmann, Rohan Sen, Mart Haitjema, Gruia-Catalin Roman, Gill Jan 2006

Mobiwork: Mobile Workflow For Manets, Gregory Hackmann, Rohan Sen, Mart Haitjema, Gruia-Catalin Roman, Gill

All Computer Science and Engineering Research

The workflow model is well suited for scenarios where many entities work collaboratively towards a common goal, and is used widely today to model complex business processes. However, the fundamental workflow model is very powerful and can be applied to a wider variety of application domains. This paper represents an initial investigation into the possibility of using workflows to model collaboration in an ad hoc mobile environment. Moving to a mobile setting introduces many challenges as the mobility of the participants in a workflow imposes constraints on allocation of workflow tasks, coordination among participants, and marshaling of results. We present …

Go to article

Discovering Weak Community Structures In Large Biological Networks , Jianhua Ruan, Weixiong Zhang Jan 2006

Discovering Weak Community Structures In Large Biological Networks , Jianhua Ruan, Weixiong Zhang

All Computer Science and Engineering Research

Identifying intrinsic structures in large networks is a fundamental problem in many fields, such as biology, engineering and social sciences. Motivated by biology applications, in this paper we are concerned with identifying community structures, which are densely connected sub-graphs, in large biological networks. We address several critical issues for finding community structures. First, biological networks directly constructed from experimental data often contain spurious edges and may also miss genuine connections. As a result, community structures in biological networks are often weak. We introduce simple operations to capture local neighborhood structures for identifying weak communities. Second, we consider the issue of …

Go to article

Design And Evaluation Of A Blast Ungapped Extension Accelerator, Master's Thesis, Joseph M. Lancaster Jan 2006

Design And Evaluation Of A Blast Ungapped Extension Accelerator, Master's Thesis, Joseph M. Lancaster

All Computer Science and Engineering Research

The amount of biosequence data being produced each year is growing exponentially. Extracting useful information from this massive amount of data is becoming an increasingly difficult task. This thesis focuses on accelerating the most widely-used software tool for analyzing genomic data, BLAST. This thesis presents Mercury BLAST, a novel method for accelerating searches through massive DNA databases. Mercury BLAST takes a streaming approach to the BLAST computation by offloading the performance-critical sections onto reconfigurable hardware. This hardware is then used in combination with the processor of the host system to deliver BLAST results in a fraction of the time of …

Go to article

Activepdf-Toolk, Washington University In St. Louis Computer Science Engineering Department Jan 2006

Activepdf-Toolk, Washington University In St. Louis Computer Science Engineering Department

All Computer Science and Engineering Research

This document provides information for deploying activePDF Toolkit Professional in a development environment. This document is organized into four sections: Getting Started, Tutorials, Technical Reference and the Toolkit Appendices. The Getting Started section covers setup and installation, includes a product overview and information related to operating Toolkit Professional. Tutorials includes examples of many Toolkit features, including PDF generation and form filling. All of the tutorials can be used with activePDF Toolkit. Technical Reference provides detailed information on Toolkit’s objects, subobjects, methods and properties.

Go to article

Fast Packet Classification Using Bloom Filters, Sarang Dharmapurikar, Haoyu Song, Jonathan Turner, John Lockwood Jan 2006

Fast Packet Classification Using Bloom Filters, Sarang Dharmapurikar, Haoyu Song, Jonathan Turner, John Lockwood

All Computer Science and Engineering Research

While the problem of general packet classification has received a great deal of attention from researchers over the last ten years, there is still no really satisfactory solution. Ternary Content Addressable Memory (TCAM), although widely used in practice, is both expensive and consumes a lot of power. Algorithmic solutions, which rely on commodity memory chips, are relatively inexpensive and power-efficient, but have not been able to match the generality and performance of TCAMs. In this paper we propose a new approach to packet classification, which combines architectural and algorithmic techniques. Our starting point is the well-known crossproducting algorithm, which is …

Go to article

Smooth Surface Reconstruction Using Charts For Medical Data, Cindy Grimm, Tao Ju Jan 2006

Smooth Surface Reconstruction Using Charts For Medical Data, Cindy Grimm, Tao Ju

All Computer Science and Engineering Research

We present a surface reconstruction technique that constructs a smooth analytic surface from scattered data. The technique is robust to noise and both poorly and non-uniformly sampled data, making it well-suited for use in medical applications. In addition, the surface can be parameterized in multiple ways, making it possible to represent additional data, such as electromagnetic potential, in a different (but related) coordinate system to the geometric one. The parameterization technique also supports consistent parameterizations of multiple data sets.

Go to article

An Improved Analysis For A Greedy Remote-Clique Algorithm Using Factor-Revealing Lps, Benjamin E. Birnbaum, Kenneth J. Goldman Jan 2006

An Improved Analysis For A Greedy Remote-Clique Algorithm Using Factor-Revealing Lps, Benjamin E. Birnbaum, Kenneth J. Goldman

All Computer Science and Engineering Research

Given a complete graph with nonnegative edge weights satisfying the triangle inequality and a positive integer p, the remote-clique problem is to find a subset of p vertices having a maximum-weight induced subgraph. A simple greedy algorithm for the problem has been shown to have an approximation ratio of 4, but a tight example has not been provided. In this paper, we use the technique of factor revealing linear programs to prove that this algorithm actually achieves an approximation ratio of 2, matching the best-known ratio for the problem. The greedy algorithm's running time of O(pn) makes it the fastest …

Go to article

The Design, Modeling, And Implementation Of Group Scheduling For Isolation Of Computations From Adversarial Interference, Terry Tidwell, Noah Watkins, Venkita Subramonian, Douglas Niehaus, Armando Gill, Migliaccio Jan 2006

The Design, Modeling, And Implementation Of Group Scheduling For Isolation Of Computations From Adversarial Interference, Terry Tidwell, Noah Watkins, Venkita Subramonian, Douglas Niehaus, Armando Gill, Migliaccio

All Computer Science and Engineering Research

To isolate computations from denial of service (DoS) attacks and other forms of adversarial interference, it is necessary to constrain the effects of interactions among computations. This paper makes four contributions to research on isolation of computations from adversarial interference: (1) it describes the design and implementation of a kernel level scheduling policy to control the effects of adversarial attacks on computations’ execution; (2) it presents formal models of the system components that are involved in a representative DoS attack scenario; (3) it shows how model checking can be used to analyze that example scenario, under default Linux scheduling semantics …

Go to article

Efficient Mapping Of Virtual Networks Onto A Shared Substrate, Jing Lu, Jonathan Turner Jan 2006

Efficient Mapping Of Virtual Networks Onto A Shared Substrate, Jing Lu, Jonathan Turner

All Computer Science and Engineering Research

Virtualization has been proposed as a vehicle for overcoming the growing problem of internet ossification [1]. This paper studies the problem of mapping diverse virtual networks onto a common physical substrate. In particular, we develop a method for mapping a virtual network onto a substrate network in a cost-efficient way, while allocating sufficient capacity to virtual network links to ensure that the virtual network can handle any traffic pattern allowed by a general set of traffic constraints. Our approach attempts to find the best topology in a family of backbone-star topologies, in which a subset of nodes constitute the backbone, …

Go to article

Adaptive Embedded Roadmaps For Sensor Networks, Gazihan Alankus, Nuzhet Atay, Chenyang Lu, Burchan Bayazit Jan 2006

Adaptive Embedded Roadmaps For Sensor Networks, Gazihan Alankus, Nuzhet Atay, Chenyang Lu, Burchan Bayazit

All Computer Science and Engineering Research

In this paper, we propose a new approach to wireless sensor network assisted navigation while avoiding moving dangers. Our approach relies on an embedded roadmap in the sensor network that always contains safe paths. The roadmap is adaptive, i.e., it adapts its topology to changing dangers. The mobile robots in the environment uses the roadmap to reach their destinations. We evaluated the performance of embedded roadmap both in simulations using realistic conditions and with real hardware. Our results show that the proposed navigation algorithm is better suited for sensor networks than traditional navigation field based algorithms. Our observations suggest that …

Go to article

A Theory Of Load Adjustments And Its Implications For Congestion Control, Sergey Gorinsky, Manfred Georg, Maxim Podlesny, Christoph Jechlitschek Jan 2006

A Theory Of Load Adjustments And Its Implications For Congestion Control, Sergey Gorinsky, Manfred Georg, Maxim Podlesny, Christoph Jechlitschek

All Computer Science and Engineering Research

Multiplicative Increase (MI), Additive Increase (AI), and Multiplicative Decrease (MD) are linear adjustments used extensively in networking. However, their properties are not fully understood. We analyze responsiveness (time for the total load to reach the target load), smoothness (maximal size of the total load oscillations after reaching the target load), fairing speed (speed of convergence to equal individual loads) and scalabilities of MAIMD algorithms, which generalize AIMD algorithms via optional inclusion of MI. We prove that an MAIMD can provide faster asymptotic fairing than a less smooth AIMD. Furthermore, we discover that loads under a specific MAIMD converge from any …

Go to article

First Prev Next Last