Digital Commons Network^™

New Architecture For Heterogeneous Real-Time Simulation, Mandar Anil Mathure

Retrospective Theses and Dissertations

This thesis investigates a new architecture for modeling and simulating complex distributed real-time systems. Modeling adequately a large distributed real time system may involve, due to its complexity, several different theoretical vehicles such as queuing theory, finite state machines, and others. Currently there are no software tools, which would offer combining such heterogeneous features into a single comprehensive simulation environment.

This study involves integrating 3 tools, SES/workbench, an offline simulator using queuing theory as its modeling discipline, ObjecTime as a real-time simulator based on finite state machines as its modeling discipline, and VxWorks real-time kernel used for free modeling in …

Evaluation Of A Compound Probability Model With Tower-Mounted Scatterometer Data, David G. Long, Benjamin E. Barrowes

Faculty Publications

Six months of data from the YSCAT94 experiment conducted at the CCIW WAVES research platform on Lake Ontario, Canada, are analyzed to evaluate a compound probability model. YSCAT was an ultrawideband small footprint (ap 1 m) microwave scatterometer that operated at frequencies of 2-18 GHz, incidence angles from 0° to 60°, both h-pol and v-pol, and which tracked the wind using simultaneous weather measurements. The probability distribution function of the measured instantaneous backscattered amplitude (p(a)) is compared to theoretical distributions developed from-the composite model and a simple wave spectrum. Model parameters of the resulting Rayleigh/generalized lognormal distribution probability density function …

Webspy: An Architecture For Monitoring Web Server Availability In A Multi-Platform Environment, Madhan M. Thirukonda

Electrical Engineering and Computer Science Faculty Publications

For an electronic business (e-business), customer satisfaction can be the difference between long-term success and short-term failure. Customer satisfaction is highly impacted by Web server availability, as customers expect a Web site to be available twenty-four hours a day and seven days a week. Unfortunately, unscheduled Web server downtime is often beyond the control of the organization. What is needed is an effective means of identifying and recovering from Web server downtime in order to minimize the negative impact on the customer. An automated architecture, called WebSpy, has been developed to notify administration and to take immediate action when Web …

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 …

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.

Annular Planar Monopole Antennas, Z. N. Chen, Max Ammann, W.Y. W. Chia, T.S. P. See

Conference papers

A type of annular planar monopole antenna is presented. The impedance and radiation characteristics of the monopole with different holes and feed gaps are experimentally examined. The measured results demonstrate that the proposed antenna is capable of providing significantly broad impedance bandwidth with acceptable radiation performance.

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.

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.

Array Pattern Nulling By Phase And Position Perturbations With The Use Of A Modified Tabu Search Algorithm, Ali̇ Akdağli, Keri̇m Güney

Turkish Journal of Electrical Engineering and Computer Sciences

A useful and flexible method based on the tabu search algorithm for the pattern synthesis of linear antenna arrays with the prescribed nulls is presented. Nulling of the pattern is achieved by controlling both the phase and the position of each array element. To show the versatility of the present method, some design specifications such as the maximum sidelobe level and the null depth level are considered by introducing a set of weighting factors in the cost function constructed for the tabu search algorithm. Several illustrative examples of a Chebyshev pattern with the imposed single, multiple and broad nulls are …

Design And Analysis Of Class Ab Rf Power Amplifier For Wireless Communication Applications, Mohamed El-Dakroury

Retrospective Theses and Dissertations

The Power Amplifier is the most power-consulting block among the building blocks of RF transceivers. It is still a difficult problem to design power amplifiers, especially for linear, low voltage operation. Until now power amplifiers for wireless applications is being produced almost in GaAs processes with some exceptions in LDMOS, Si BJT, and SiGe HBT. The submicron CMOS processes for power amplifiers are under research focus since CMOS offers integration for power amplifier with rest of the transceivers blocks due to its high yield. Also CMOS process is cheap.

This thesis report details the design process of a class AB …

High Frequency Communication System Modeling And Performance Enhancement, Employing Novel Adaptive Dsp Techniques, Murad M. Qahwash

Retrospective Theses and Dissertations

High Frequency (HF) communication has been shown to be a useful communication technique from the very beginning of World War I and it accelerated during World War II. This is attributed to its simplicity, ability to provide near globe connectivity at low power without repeaters, moderate cost, and ease of proliferation [1]. In fact, the HF communication system utilizes the ionosphere [2][3][4] to refract the skywave signals to a distant receiver. This ionospheric channel has some disadvantages. First, it is a non-stationary channel as the HF frequency propagation is a function of the sun spot activities, solar winds, and diurnal …

Hybrid Sr Arq Scheme Using Trellis Coded Modulation For Point-To-Multipoint Communication Over Nonstationary Channels, Necmi̇ Taşpinar

Turkish Journal of Electrical Engineering and Computer Sciences

In this paper, a type-I hybrid SR ARQ scheme using trellis coded modulation (TCM) for point-to-multipoint communication was analyzed on nonstationary broadcast channels where the channel bit error rate (BER) varies over time. A nonstationary channel is modelled as a two-state Markov chain. In the numerical calculations, it is found that, for a given p_{1} and \bar \varepsilon , the values of the average burst length \bar b have a very small influence on the throughput. Numerical results show that the throughput is better for values between 10 ^{-6} and 10 ^{-4}of average bit error rate \bar \varepsilon if the …

Towards An Expert System Approach For Pi Controller Design Of Delayed Processes, Michael Feeney, Aidan O'Dwyer

Conference papers

This paper will discuss the compensation of first order lag plus time delay (FOLPD) processes using PI controllers whose parameters are specified using appropriate tuning rules. The gain margin and phase margin of the compensated system, as the ratio of time delay to time constant of the process varies, are calculated for each tuning rule and an expert system is used to recommend a tuning rule for user defined requirements.

Mobile Home Security With Gprs, Duy Nguyen

Theses : Honours

This thesis presents the results of an honours project on the development of a security system for use on mobile devices. Mobile Home Security (MHS) is a prototype system that aimed to fully investigate a potential use of the wireless high-speed technology General Packet Radio Service (GPRS) in transmitting video from a static location. This thesis Mobile Home Security with GPRS describes in detail the design and developmental stages for the system. The research focused on the sending of video from a security capture device over a high speed radio network. The first stage of the research involved the design …

Power Bus Isolation Using Power Islands In Printed Circuit Boards, J. Chen, Todd H. Hubing, Richard E. Dubroff, Thomas Van Doren

Electrical and Computer Engineering Faculty Research & Creative Works

Power islands are often employed in printed circuit board (PCB) designs to alleviate the problem of power bus noise coupling between circuits. Good isolation can be obtained over a wide frequency band due to the large series impedance provided by the gap between the power islands. However, power bus resonances may degrade the isolation at high frequencies. The amount of isolation also depends on the type of connection between power islands and the components on the board. This paper experimentally investigates the effectiveness of several power island structures up to 3.0 GHz

Video Indexing And Retrieval Techniques Using Novel Approaches To Video Segmentation, Characterization, And Similarity Matching, Waleed Ezzat Farag

Computer Science Theses & Dissertations

Multimedia applications are rapidly spread at an ever-increasing rate introducing a number of challenging problems at the hands of the research community, The most significant and influential problem, among them, is the effective access to stored data. In spite of the popularity of keyword-based search technique in alphanumeric databases, it is inadequate for use with multimedia data due to their unstructured nature. On the other hand, a number of content-based access techniques have been developed in the context of image indexing and retrieval; meanwhile video retrieval systems start to gain wide attention, This work proposes a number of techniques constituting …

Self-Assembly Of Spatially Separated Silicon Structures By Si Heteroepitaxy On Ni Disilicide, Elena A. Guliants, Chunhai Ji, Wayne A. Anderson

Electrical and Computer Engineering Faculty Publications

A nonlithographic approach to produce self-assembled spatially separated Si structures for nanoelectronic applications was developed, employing the metal-induced silicon growth. Densely packed Si whiskers, 500–800 nm thick and up to 2500 nm long, were obtained by magnetron sputtering of Si on a 25 nm thick Ni prelayer at 575 °C. The nucleation of the NiSi2 compound at the Ni–Si interface followed by the Si heteroepitaxy on the lattice-matched NiSi2 is suggested to be the driving force for the whisker formation.

Efficient Convolvers Using The Polynomial Residue Number System Technique, Surendar Paruchuri

LSU Master's Theses

The problem of computing linear convolution is a very important one because with linear convolution we can mechanize digital filtering. The linear convolution of two N-point sequences can be computed by the cyclic convolution of the following 2N-point sequences. The original sequence padded with N zero’s each. The cyclic convolution of two N-point sequences requires multiplications and additions for its computation. A very efficient way of computing cyclic convolution of two sequences is by using the Polynomial Residue Number System (PRNS) technique. Using this technique the cyclic convolution of two N-point sequences can be computed using only N multiplications instead …

Wavelength Assignment In All-Optical Networks For Mesh Topologies, Prabhulaiah Bijja

LSU Master's Theses

All-Optical Networks employing Dense Wavelength Division Multiplexing (DWDM) are believed to be the next generation networks that can meet the ever-increasing demand for bandwidth of the end users. This thesis presents some new heuristics for wavelength assignment and converter placement in mesh topologies. Our heuristics try to assign the wavelengths in an efficient manner that results in very low blocking probability. We propose novel static and dynamic assignment schemes that outperform the assignments reported in the literature even when converters are used. The proposed on-line scheme called "Round-Robin" assignment outperforms previously proposed strategies such as first-fit and random assignment schemes. …

Computing Moments Of A Binary Horizontally/Vertically Convex Image Using Run-Time Reconfiguration, Cheowway Neoh

LSU Master's Theses

In this thesis, we present a design for computing moments of a binary horizontally/vertically convex image on an FPGA chip, using run-time reconfiguration. We compute the moments of up to third order for a total of 16 moments. We address how run-time reconfiguration speeds up moment computations without taking up huge hardware resources. Since we are considering a binary horizontally/vertically convex image, we look at an alternative method in moment computations that utilizes constant coefficient multipliers. We divide the image into segments and process one segment at a time. We reconfigure the constant coefficient multipliers before processing the next segment. …

Simulating Quantum Transport In Nanoscale Mosfets: Real Vs. Mode Space Approaches, Rajesh Venugopal, Z. Ren, Supriyo Datta, Mark S. Lundstrom, D. Jovanovic

Department of Electrical and Computer Engineering Faculty Publications

The performance limits of carbon nanotube field-effect transistors (CNTFETs) are examined theoretically by extending a one-dimensional treatment used for silicon metal–oxide–semiconductor field-effect transistors (MOSFETs). Compared to ballistic MOSFETs, ballistic CNTFETs show similar I–VI–V characteristics but the channel conductance is quantized. For low-voltage, digital applications, the CNTFET with a planar gate geometry provides an on-current that is comparable to that expected for a ballistic MOSFET. Significantly better performance, however, could be achieved with high gate capacitance structures. Because the computed performance limits greatly exceed the performance of recently reported CNTFETs, there is considerable opportunity for progress in device performance.

Adaptive Radio Resource Management For 2.5g Cellular Networks, Ken Murray

Theses

Recent years have seen a dramatic increase in demand for mobile communication services and with the introduction of 2.5G services such as general packet radio service, this trend is expected to increase further. These new services will introduce highly dynamic tele-traffic variations due to the inherent variability in resource usage of the new data services. The net effect will be considerable increase in load on the available radio resources. The currently employed fixed channel allocation scheme lacks the flexibility to support such traffic variations. A plethora of dynamic channel allocation schemes have been proposed in the past in an effort …

Design And Analysis Of Radio Frequency Deployment Algorithms For Gsm, Mónica Pérez-Carbonell

Theses

Due to the growth of the subscriber base and the introduction of new services, mobile communications networks’ demand for wireless resources is increasing. This has resulted in an increasing need to change the frequency allocation of a network in order to adapt the cellular network to new frequency demands.

Currently, a planning tool generates a new frequency plan, which is. then deployed to cell sites. The deployment should ideally be carried out with minimum disruption to network operation, which makes this deployment process a critical undertaking as any errors during or after the deployment can leave the network with poor …

A Congestion Controlled Logical Topology For Multihop Optical Networks, U. Bhattacharya, D. Datta, Badrul H. Chowdhury, G. C. Saha, B. K. Sikdar

Electrical and Computer Engineering Faculty Research & Creative Works

This paper considers the problem of designing the logical topology for any wavelength routed optical network, given the traffic matrix. An heuristic algorithm is proposed here for designing topologies based on the De-Bruijn graph and we compare our results with those obtained through the deterministic approach. The De-Bruijn graph is selected in this context as the logical topology due to some of its characteristic features like simple routing scheme, low diameter and small degree.

Novel Time Domain Radiowave Propagators For Wireless Communication Systems, Funda Akleman, M. O. Özyalçin, Levent Sevgi̇

Turkish Journal of Electrical Engineering and Computer Sciences

In this study, novel time domain wave propagators are used in path loss calculations for macro and micro cell coverage planning in wireless communication systems. Both Transmission Line Matrix (TLM) and Finite-Difference Time-Domain (FDTD) based propagators, which were introduced recently and validated and verified on different canonical propagation scenarios, are used for this purpose. Examples are chosen both in rural and urban areas, where two propagators are compared with each other. Excellent agreement between the results obtained via two propagators is presented. The results presented here are very encouraging and these propagators are shown to be powerful tools for not …

Gain-Bandwidth Characteristics Of Thin Avalanche Photodiodes, Majeed M. Hayat, Oh-Hyun Kwon, Yi Pan, Paul P. Sotirelis, Joe C. Campbell, Bahaa E.A. Saleh, Malvin Carl Teich

Electrical and Computer Engineering Faculty Research and Publications

The frequency-response characteristics of avalanche photodiodes (APDs) with thin multiplication layers are investigated by means of a recurrence technique that incorporates the history dependence of ionization coefficients. In addition, to characterize the autocorrelation function of the impulse response, new recurrence equations are derived and solved using a parallel computer. The mean frequency response and the gain-bandwidth product are computed and a simple model for the dependence of the gain-bandwidth product on the multiplication-layer width is set forth for GaAs, InP, Al/sub 0.2/Ga/sub 0.8/As, and In/sub 0.52/Al/sub 0.48/As APDs. It is shown that the dead-space effect leads to a reduction (up …

Maximum-Likelihood Image Estimation Using Photon-Correlated Beams, Majeed M. Hayat, Muhammad Sajjad Abdullah, Adel Joobeur, Bahaa E.A. Saleh

Electrical and Computer Engineering Faculty Research and Publications

A theory is presented addressing the fundamental limits of image estimation in a setup that uses two photon-correlated beams. These beams have the property that their photon arrivals, as a point process, are ideally synchronized in time and space. The true image represents the spatial distribution of the optical transmittance (or reflectance) of an object. In this setup, one beam is used to probe the image while the other is used as a reference providing additional information on the actual number of photons impinging on the object. This additional information is exploited to reduce the effect of quantum noise associated …

A Distributed Discrete-Time Neural Network Architecture For Pattern Allocation And Control, A.T. Chronopoulos, Jagannathan Sarangapani

Computer Science Faculty Research & Creative Works

No abstract provided.