Digital Commons Network^™

Qos Routing Source Routing Problems And Solutions, Ye Tian

Theses

The notion of Quality-of-Service has been proposed to capture qualitatively or quantitatively defined performance contracts between the service provider and the user applications. Integrated network services are designed to support Quality-of-Service (QoS). One of the primary goals for the integrated network services is to find the paths that satisfy given QoS requirements, namely QoS routing. The challenging issue in this area is to route packets subjected to multiple uncorrelated constraints because the problem is inherently NP-complete. This thesis studies the source routing heuristic approaches that bring the time complexity down to the polynomial-time for the multi-constrained path (MCP) problem. A …

Cxquery: A Novel Xml Query Language, Peter Revesz, Yi Chen

School of Computing: Conference and Workshop Papers

XML is becoming the data exchange standard on the Internet. Previously proposed XML query languages, such as XQuery, Quilt, YALT, Lorel, and XML-QL, lack schema definition of the query result; therefore, they are limited for defining views, integrating data, updating, and further querying, all of which are often needed in e-Business applications. We propose a novel XML query language called CXQuery, which defines the schema of the query results explicitly and can easily define views, and integrate, update, and query XML data. In addition, CXQuery can express spatial and spatio-temporal queries using a constraint-based querying approach.

Implementation Of A Si/Sic Hybrid Optically Controlled High-Power Switching Device, Prashant Bhadri, Kuntao Ye, Elena A. Guliants, Fred R. Beyette Jr.

Electrical and Computer Engineering Faculty Publications

The ever-increasing performance and economy of operation requirements placed on commercial and military transport aircraft are resulting in very complex systems. As a result, the use of fiber optic component technology has lead to high data throughput, immunity to EMI, reduced certification and maintenance costs and reduced weight features. In particular, in avionic systems, data integrity and high data rates are necessary for stable flight control. Fly-by-Light systems that use optical signals to actuate the flight control surfaces of an aircraft have been suggested as a solution to the EMI problem in avionic systems. Current fly-by-light systems are limited by …

Translation Of 'Balika Badhu: A Selected Anthology Of Bengali Short Stories', Monish Ranjan Chatterjee

Electrical and Computer Engineering Faculty Publications

This project, which began with the desire to render into English a rather long tale by Bimal Kar about five years ago, eventually grew into a considerably more extended compilation of Bengali short stories by 10 of the most well-known practitioners of that art since the heyday of Rabindranath Tagore. The collection is limited in many ways, not the least of which being that no woman writer has been included, and that it contains only a baker's dozen stories (if we count Bonophool's micro-stories collectively as one ) — a number pitifully small considering the vast and prolific field of …

Wireless Lans, Jack Glas, Mihai Banu, Joachim Hammerschmidt, Vladimir I. Prodanov, Peter Kiss

Electrical Engineering

Wireless LANs based on the IEEE 802.11 standard have achieved wide customer acceptance in the enterprise environment. They are expected to continue to expand in popularity and become ubiquitous communication systems even in private and public places. This paper discusses the basics of the wireless LAN physical layer, focusing on radio transceiver specifications and design options.

Automatic Speechreading With Applications To Human-Computer Interfaces, Xiaozheng Zhang, Charles C. Broun, Russell M. Mersereau, Mark A. Clements

Electrical Engineering

There has been growing interest in introducing speech as a new modality into the human-computer interface (HCI). Motivated by the multimodal nature of speech, the visual component is considered to yield information that is not always present in the acoustic signal and enables improved system performance over acoustic-only methods, especially in noisy environments. In this paper, we investigate the usefulness of visual speech information in HCI related applications. We first introduce a new algorithm for automatically locating the mouth region by using color and motion information and segmenting the lip region by making use of both color and edge information …

Parameter Estimation For Transformer Modeling, Sung Don Cho

Dissertations, Master's Theses and Master's Reports - Open

Large Power transformers, an aging and vulnerable part of our energy infrastructure, are at choke points in the grid and are key to reliability and security. Damage or destruction due to vandalism, misoperation, or other unexpected events is of great concern, given replacement costs upward of $2M and lead time of 12 months. Transient overvoltages can cause great damage and there is much interest in improving computer simulation models to correctly predict and avoid the consequences.

EMTP (the Electromagnetic Transients Program) has been developed for computer simulation of power system transients. Component models for most equipment have been developed and …

Effect Of Ga Content On Defect States In Cuin1-XGaXSe2 Photovoltaic Devices, Jennifer T. Heath, J. David Cohen, William N. Shafarman, Dongxiang Liao, Angus Rockett

Faculty Publications

Defects in the band gap of CuIn_1-xGa_xSe₂ have been characterized using transient photocapacitance spectroscopy. The measured spectra clearly show response from a band of defects centered around 0.8 eV from the valence band edge as well as an exponential distribution of band tail states. Despite Ga contents ranging from Ga/(In+Ga)=0.0 to 0.8, the defect bandwidth and its position relative to the valence band remain constant. This defect band may act as an important recombination center, contributing to the decrease in device efficiency with increasing Ga content.

Multiple Model Networks In Non-Linear System Modelling For Control – A Review, Ruiyao Gao, Aidan O'Dwyer

Conference papers

Non-linear processes, by their nature, are non-uniform and invariably require custom designed control schemes to deal with individual characteristics. No general theory deals comprehensively with the wide range of non-linear systems encountered. In an attempt to accurately model non-linear dynamical systems, a wide variety of techniques have been developed such as non-linear auto-regressive moving average with exogeneous inputs (NARMAX) models (Chen and Billings, 1989), Weiner models (Schetzen, 1981), Hammerstein models (Billings and Fakhouri, 1982) and Multiple Layer Perceptron (MLP) neural networks (Narendra and Kannan, 1990). While the accuracy of such models offers a potentially significant improvement over linear models, the …

The Effect Of Weak Acids Hydrolysis On The Sol-Gel Fabrication Of Silica Thin Film, Abdul Hamid

Student Works (2000-2009)

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A Vhdl Implementation Of Bist Technique In Uart Design, Mohd. Yamani Idna Idris

Student Works (2000-2009)

No abstract provided.

Modelling Of Space Charge Effects In The Electrical Discharge Of Nitrogen Gas Laser, Chin Yang Chia

Student Works (2000-2009)

A computer model for the simulation of a nitrogen gas discharge has been built and studied. This model was based on the fluid description of the discharge plasma. The Phoenical SHASTA Flux-Corrected Transport (FCT) algorithm is used for the solution of the fluid equations and its accuracy has been tested. The distribution of the local electrical field was calculated by the Poisson equation. The internal discharge current was calculated by Sato's equation. The motion of the charge particles was taken into account. The electrical discharge behavior was simulated by the circuit equation and solved using the fourth order Runge-Kutta method …

Design Of Low Phase Drift Cmos Frequency Synthesisers, Cyril Patrick Hervé Florent Lahuec

Theses

This thesis presents a methodology for the development of high performance video clock synthesisers that have high (2000) input to output clock multiplication ratios. The synthesisers are required to be compatible with standard CMOS technologies and they must exhibit very low drift between their input and output clocks.

The methodology used borrows techniques established for RF synthesisers in the GHz range. In the RF domain there are significant constraints on spectral spread and because of this there has been significant interest in phase noise generated by intrinsic device noise. Simple and accurate models were developed that help understand the up …

Servo Response And Modelling Issues In Generalised Predictive Control, Ben Griffin

Theses

One of the more popular control strategies, of late, is the Generalised Predictive Controller (GPC). It has received widespread dissemination in academia and numerous successful applications in industry testify to its usefulness. Its popularity partly stems from its superiority to its predecessors, e.g. the generalised minimum variance and pole-placement controllers, but also from the GPC ‘tuning knobs’, which have simple time-domain interpretations and extremely robust default settings. However, despite the widespread interest, there would appear to be some issues relating to the specification of the closed-loop serv^o response that have not been covered in any great detail in the GPC …

A 0.5 Μm Thick Polysilicon Schottky Diode With Rectification Ratio Of 10^6, Elena A. Guliants, Chunhai Ji, Young J. Song, Wayne A. Anderson

Electrical and Computer Engineering Faculty Publications

Polycrystalline Si films, 0.5-mm thick, were obtained as a result of metal-induced growth by sputtering from a Si target on 25 nm thick Ni prelayers at 525 °C. Silicon grew heteroepitaxially on the NiSi2 layer formed due to the reaction between the sputtered Si atoms and Ni. Schottky diodes were fabricated on the Si films by deposition of a Schottky metal on the front surface of the film while Ni disilicide provided an intimate ohmic contact at the back. A Pd/n-Si diode using an n-Si film annealed for 2 h at 700 °C in forming gas demonstrated a rectification ratio …

Improved Energy Model For Membrane Electroporation In Biological Cells Subjected To Electrical Pulses, R. P. Joshi, Q. Hu, K. H. Schoenbach, H. P. Hjalmarson

Bioelectrics Publications

A self-consistent model analysis of electroporation in biological cells has been carried out based on an improved energy model. The simple energy model used in the literature is somewhat incorrect and unphysical for a variety of reasons. Our model for the pore formation energy E(r) includes a dependence on pore population and density. It also allows for variable surface tension, incorporates the effects of finite conductivity on the electrostatic correction term, and is dynamic in nature. Self-consistent calculations, based on a coupled scheme involving the Smoluchowski equation and the improved energy model, are presented. It is shown that E(r) becomes …

Electrical Network-Based Time-Dependent Model Of Electrical Breakdown In Water, R. P. Joshi, J. Qian, K. H. Schoenbach

Bioelectrics Publications

A time-dependent, two-dimensional, percolative approach to model dielectric breakdown based on a network of parallel resistor–capacitor elements having random values, has been developed. The breakdown criteria rely on a threshold electric field and on energy dissipation exceeding the heat of vaporization. By carrying out this time-dependent analysis, the development and propagation of streamers and prebreakdown dynamical evolution have been obtained directly. These model simulations also provide the streamer shape, characteristics such as streamer velocity, the prebreakdown delay time, time-dependent current, and relationship between breakdown times, and applied electric fields for a given geometry. The results agree well with experimental data …

Sar Simulations In Wireless Communication And Safety Discussions In The Society, M. O. Özyalçin, Funda Akleman, Levent Sevgi̇

Turkish Journal of Electrical Engineering and Computer Sciences

Numerical simulation in cellular phone - human tissue interaction is discussed in this paper. The powerful time domain (TD) techniques, the transmission line matrix (TLM) and the finite-difference time-domain (FDTD) methods, are used to model mutual effects. The purpose is to calculate specific absorption rate (SAR; defined as the power absorbed by the unit mass of the tissue), validate the codes and verify the results. Also, effectiveness of the SAR parameter in determination of the exposure limits for human health and environmental pollution is discussed.

Modeling, Fabrication, And Optimization Of Niobium Cavities, Robert A. Schill Jr., Mohamed Trabia, Yitung Chen

Transmutation Sciences Materials (TRP)

All technologies for the transmutation of nuclear waste require a large source of neutrons. One of the principal methods of generating these neutrons is by using a particle accelerator to bombard a heavy metal target. One of the more promising designs for particle accelerators for transmutation systems is the Superconducting Radio Frequency (RF) high-current linear accelerator (linac). The power supplies for these systems have three major components: niobium cavities, power couplers, and cryomodules. This research project will develop models to predict the behavior and performance of the niobium cavities, which will then be used to design and optimize the superconducting …

Cpl: A Language For Real-Time Distributed Object Programming, Erhan Saridoğan, Nadi̇a Erdoğan

Turkish Journal of Electrical Engineering and Computer Sciences

As processing and time requirements of computer systems increase over the borders of single processor architectures, it is becoming more and more attractive to use distributed computing with additional real-time capabilities. In several cases, traditional programming languages have become insufficient to build distributed systems easily, especially when real-time issues and basic software quality factors are concerned. In this paper, a concurrent, object-oriented, distributed real-time programming language, CPL, with a supportive run-time system, namely the CORD-RTS, is introduced and new language features are described. The new language provides an efficient solution for command and control systems by embedding distribution and real-time …

An Efficient Middleware Architecture Supporting Real-Time Distributed Object Programming, Erhan Saridoğan, Nadi̇a Erdoğan

Turkish Journal of Electrical Engineering and Computer Sciences

With the increasing demand for distributed real-time systems, the need for programming tools and execution platforms useful in development of such application systems is widely recognized. This paper presents CORD-RTS, an efficient middleware architecture that provides support for real-time distributed object programming. The communication infrastructure and various components of the middleware, which support several modes of interactions among distributed real-time objects, along with its real-time features and services, are discussed in detail.

A New Congestion Control Mechanism Proposed For The Sscop Protocol, A. Hali̇m Zai̇m

Turkish Journal of Electrical Engineering and Computer Sciences

International Telecommunication Union, Telecommunications Sector (ITU-T) Recommendation Q.2110 states that the update of a granted credit window to the transmitter (VR(MR)) is implementation dependent. In this paper, a new algorithm is designed to control the traffic flow coming from malfunctioning users. The VR(MR) parameter is controlled for that purpose. The simulation results show that this new technique nearly doubles the system performance.

Walkthrough In Complex Environments At Interactive Rates Using Level-Of-Detail, Alper Selçuk, Uğur Güdükbay, Bülent Özgüç

Turkish Journal of Electrical Engineering and Computer Sciences

One of the biggest problems in computer graphics is displaying huge geometric models at interactive rates. A lot of work has been done to achieve the required frame-rates in architecture, simulation, computer-aided design and entertainment applications. In this paper, a system that enables walkthrough in complex environments using level-of-detail approximations is explained. The system uses hierarchical triangulated models as input. In the preprocessing phase, multiresolution models of objects are created using polygonal simplification techniques. During walkthrough, fast frustum culling based on bounding boxes is performed to eliminate branches of hierarchy that are not visible. An appropriate level for detail of …

A New Petri-Net-Based Synthesis Technique For Supervisory Control Of Discrete Event Systems, Murat Uzam, Anthony H. Jones

Turkish Journal of Electrical Engineering and Computer Sciences

A new Petri-net-based top-down synthesis technique for supervisory control of Discrete Event Systems (DES) is proposed to solve the forbidden state problem. The supervisors obtained are compiled supervisors, whose control policy is represented as a net structure, as opposed to mapping supervisors, whose control policy is computed as a feedback function of the marking of the system. The compiled supervisors obtained by using the technique proposed in this paper are both nonblocking and maximally permissive. The supervisors to be synthesised consist of a controlled Automation Petri Net model of the system. Automation Petri Nets (APN) include the following extensions to …

Approximations On The Aggregate Mpeg Video Traffic And Their Impact On Admission Control, Fati̇h Alagöz

Turkish Journal of Electrical Engineering and Computer Sciences

In this paper, we investigate the aggregate traffic approximations for the Motion Pictures Expert Group (MPEG) coded variable bit rate (VBR) video traffic and their impact on admission control at a desired Quality of Service (QoS) level. In order to generate the MPEG coded VBR video traffic, we use a novel source model that employs a mixture of two first-order autoregressive processes with lognormally distributed residuals (2LAR). The model parameters are found based on least square estimates to capture the marginal distribution and autocorrelation function as well as the single server queuing behavior of an MPEG coded empirical bitstream. We …

New Oscillator Topologies Using Inverting Second-Generation Current Conveyors, Ali̇ Toker, Hakan Kuntman, Oğüzhan Çi̇çekoğlu, Mehmet Di̇şçi̇gi̇l

Turkish Journal of Electrical Engineering and Computer Sciences

In this work, new oscillator topologies based on a recently introduced active element, namely inverting second-generation current conveyor, are presented. This recently introduced unity gain based active element is suitable for integrated circuit realization and can easily be implemented with CMOS technology. Considering this fact, basic oscillator topologies employing a single, two and three conveyors are proposed. Several oscillator circuits based on these topologies are obtained. Expressions for oscillation conditions and frequencies are derived both for ideal and non-ideal cases. Some of them are single frequency and the others are variable frequency oscillators. The oscillators employing two and three active …

Preface, Levent Sevgi̇

Turkish Journal of Electrical Engineering and Computer Sciences

No abstract provided.

Electromagnetic Engineering In The 21^{St} Century: Challenges And Perspectives, Leopold B. Felsen, Levent Sevgi̇

Turkish Journal of Electrical Engineering and Computer Sciences

This paper aims at a broad-brush look at certain technological and educational challenges that confront wave-oriented electromagnetic (EM) engineering in the 21^{st} century, in a complex computer and technology-driven world with rapidly shifting societal and technical priorities. Simulation strategies for complex EM systems, both analytic and numerical, are reviewed and categorized, and are illustrated on selected practical complex multicomponent system scenarios currently under investigation in Turkey. Educational issues to ensure proper multidisciplinary exposure of new generations of computer-weaned students, who will have to deal with these problems, are touched upon as well.

Time-Domain Simulation Of Thin Material Boundaries And Thin Panels Using Digital Filters In Tlm, J. Paul, V. Podlozny, Dave Thomas, C. Christopoulos

Turkish Journal of Electrical Engineering and Computer Sciences

In this paper, the design and implementation of digital filters for the time-domain simulation of electromagnetic wave interaction with thin material boundaries and thin panels using the Transmission-Line Modelling (TLM) method are described. The technique is applied to the description of thin ferrite layers placed on the external boundaries of the modelled space and to plastic panels placed inside the modelled space. The approach is validated using one-dimensional examples having analytic solutions. Finally, the results obtained for the Shielding Effectiveness (SE) of a practical equipment enclosure are presented to demonstrate the utility of the method in Electromagnetic Compatibility (EMC) prediction.

Aspects Of Radar Polarimetry, Ernst Luneburg

Turkish Journal of Electrical Engineering and Computer Sciences

This contribution is a tutorial introduction to the phenomenological theory of radar polarimetry for the coherent scatter case emphasizing monostatic backscattering and forward scattering (transmission). Characteristic similarities and differences between radar polarimetry and optical polarimetry and the role of linear and antilinear operators (time-reversal) are pointed out and typical polarimetric invariants are identified.