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Theses/Dissertations

1995

Electrical and Computer Engineering

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Articles 1 - 30 of 98

Full-Text Articles in Engineering

Design And Development Of Four To Sixteen Channel Video Multiplexers, Ronan Rahimi Dec 1995

Design And Development Of Four To Sixteen Channel Video Multiplexers, Ronan Rahimi

Theses

Video multiplexer series were successfully designed and built for prototype and evaluation both in terms of hardware and software. The hardware platform was designed to accommodate up to sixteen color video input channels for time lapse or real time recording on a single video cassette recorder. This product implements four modes of operation; Live, Record, Playback and Menu mode, which is not a full mode of operation. Menu mode is a series of on-screen programming menus which appears on Live, Record and Playback modes. Menu mode enables the user to program the machine to work under specific modes of application ...


The Development Of An Embedded Wireless Modem Conforming To Advanced Mobile Phone System And Cellular Digital Packet Data Standards, Xin Ren Dec 1995

The Development Of An Embedded Wireless Modem Conforming To Advanced Mobile Phone System And Cellular Digital Packet Data Standards, Xin Ren

Theses

Introduced by AT&T Bell Labs in 1970s, today Advanced Mobile Phone Systems (AMPS) - a first generation analog cellular system serve millions of customers in the United States and 55 other countries, and the number of subscribers is still rapidly increasing. Although digital cellular systems are emerging in recent years, research efforts are still being made to the enhancement of AMPS systems because of their popularity. An example is the new Cellular Digital Packet Data (CDPD) standard announced in 1994. CDPD is an overlay of the existing AMPS, and has the capability of transmitting data packets over such an analog ...


A Comparative Study Of Image Compress Schemes, Kui Wang Dec 1995

A Comparative Study Of Image Compress Schemes, Kui Wang

Theses

Image compression is an important and active area of signal processing. All popular image compression techniques consist of three stages: Image transformation, quantization (lossy compression only), and lossless coding (of quantized transform coefficients).

This thesis deals with a comparative study of several lossy image compression techniques. First, it reviews the well-known techniques of each stage. Starting with the first stage, the techniques of orthogonal block transformation and subband transform are described in detail. Then the quantization stage is described, followed by a brief review of the techniques for the third stage, lossless coding.

Then these different image compression techniques are ...


On The Adaptive Multi-Stage Detector For Cancellation Of Multiuser Interference In Cdma Wireless Communication Systems, Nadir Sezgin Dec 1995

On The Adaptive Multi-Stage Detector For Cancellation Of Multiuser Interference In Cdma Wireless Communication Systems, Nadir Sezgin

Dissertations

The classical multiple access techniques such as Frequency Division Multiple Access (FDMA) and Time Division Multiple Access (TDMA) schemes are band limited in terms of their capacity to be used for mobile radio communication. Recent developments in the area of digital signal processing, makes Code Division Multiple Access (CDMA) as a possible solution to the demand of capacity for the mobile radio communication. The capacity of CDMA is limited by multiuser interference, that is the interference from the other users.

The goal of this dissertation is to improve the multiuser CDMA detector with high Bit Error Rate (BER) performance, low ...


Adaptive Space-Time Processing For Wireless Communications, Xiao Cheng Bernstein Dec 1995

Adaptive Space-Time Processing For Wireless Communications, Xiao Cheng Bernstein

Dissertations

Adaptive space-time processing techniques have been found to increase the capacity of two major, multiple-access wireless communication systems: Time Division Multiple Access (TDMA) and Code Division Multiple Access (CDMA).

In an IS-54 TDMA system, the frequency re-use factor has to be set to 7 so that cells with the same spectrum are separated far enough to meet a required carrier-to-interference ratio (CIR). Space processing uses multiple antennas which, in turn, provide alternative signal paths in order to cancel interferences and combat multipath fading. We have proposed the eigencanceler method and have reviewed the theoretical optimum combining and the feasible direct ...


On Optimal Design And Applications Of Linear Transforms, Mehmet V. Tazebay Dec 1995

On Optimal Design And Applications Of Linear Transforms, Mehmet V. Tazebay

Dissertations

Linear transforms are encountered in many fields of applied science and engineering. In the past, conventional block transforms provided acceptable answers to different practical problems. But now, under increasing competitive pressures, with the growing reservoir of theory and a corresponding development of computing facilities, a real demand has been created for methods that systematically improve performance. As a result the past two decades have seen the explosive growth of a class of linear transform theory known as multiresolution signal decomposition. The goal of this work is to design and apply these advanced signal processing techniques to several different problems.

The ...


On The Optimization Problems In Multiaccess Communication Systems, Gangsheng Wang Dec 1995

On The Optimization Problems In Multiaccess Communication Systems, Gangsheng Wang

Dissertations

In a. communication system, the bandwidth is often a primary resource. In order to support concurrent access by numerous users in a network, this finite and expensive resource must be shared among many independent contending users. Multi-access protocols control this access of the resource among users to achieve its efficient utilization, satisfy connectivity requirements and resolve any conflict among the contending users. Many optimization problems arise in designing a multi-access protocol. Among these, there is a class of optimization problems known as NP-complete, and no polynomial algorithm can possibly solve them. Conventional methods may not be efficient arid often produce ...


Comparison Of Adaptive Radar Algorithms : Transformed Smi, Eigencanceler, And Smi, Chaitanya H. Kathiari Dec 1995

Comparison Of Adaptive Radar Algorithms : Transformed Smi, Eigencanceler, And Smi, Chaitanya H. Kathiari

Theses

Advanced airborne radars must perform target detection in the presence of interference and heavy clutter. In many applications, the practical usefulness of adaptive arrays is limited by their convergence rate. In this paper, we first analyze the performance of the SMI method. Then, two other methods, the transformed SMI and the eigencanceler, both based on the principle component inversion (PCI) technique, are described and analyzed by simulation. It is shown by simulation based comparison that the transformed SMI and the Eigencanceler outperform the SMI method. It is also shown that the transformed SMI and the eigencanceler has higher convergence rate ...


Numerical Simulation Of Clipping Distortion In Lightwave Catv Systems, Luay Al-Nadi Dec 1995

Numerical Simulation Of Clipping Distortion In Lightwave Catv Systems, Luay Al-Nadi

Theses

Clipping induced distortion is an essential limit for modulation depth and number of channels in subcarrier multiplexed lightwave video transmission systems. Two different types of laser clipping are compared (single-clipping vs. double-clipping). In this work, the distortion limits imposed by clipping effects, in both directly (single-clipping) and externally (double-clipping) modulated systems, are examined. Numerical simulations were performed to test the efficiency of Saleh's Model. A comparison of results with clipping induced distortion in directly modulated lightwave systems (single-clipping) and clipping induced distortion in externally modulated lightwave systems (double-clipping) is presented, it is shown through numerical simulation that the total ...


Analysis Of Calibration, Robustness, Detection Of Space-Time Adaptive Rada Using Experimental Data, Murat O. Berin Dec 1995

Analysis Of Calibration, Robustness, Detection Of Space-Time Adaptive Rada Using Experimental Data, Murat O. Berin

Theses

Signal cancellation effects in adaptive array radar are studied under non ideal conditions when there is a mismatch between the true desired signal and the presumed theoretical desired signal. This mismatch results in decreased performance when the estimated correlation matrix has a large desired signal component. The performance of the sample matrix inversion (SMI) method is compared to the eigenanalysis-based eigencanceler method. Both analytical results and the processing on the experimental data from the Mountaintop Program, show that eigenanalysis-based adaptive beamformers have greater robustness to signal cancellation effects than the SMI method. Also, the calibration of the recorded data, and ...


Implementation Of A Friction Estimation And Compensation Technique, Jayesh N. Amin Dec 1995

Implementation Of A Friction Estimation And Compensation Technique, Jayesh N. Amin

Theses

This thesis reports implementation of a friction estimation and compensation technique on a special laboratory apparatus. In this work, experimental results are reported for the Coulomb friction observer.

The Coulomb friction observer estimates the total friction present in a system, assuming it to be a constant function of velocity. An extension of the observer, utilizing a coupled velocity observer, is used when velocity is not measurable. A modification to the velocity observer is also implemented. Experimental results show a remarkable improvement in the friction estimates which are also compared to the actual friction measurements. The estimates are qualitatively similar to ...


Adaptive Radar In Heterogeneous Environment, Albert Futernik Dec 1995

Adaptive Radar In Heterogeneous Environment, Albert Futernik

Theses

Radar performance in heterogeneous clutter has been a much studied topic. In all the studies so far, various forms of the sample matrix inversion (SMI) technique where used to calculate the weight vector of the processor. In this thesis an eigenanalysis-based technique known as the eigencanceler, is used. Performance of this technique is compared to the performance of the generalized likelihood ration (GLR) processor. This comparison is done using the clutter edge model, in which there is an abrupt change in the clutter power in the reference window. It is shown that the false alarm rate fluctuations, of the cell ...


Gabor Expansion Of An Equivalent Dipole Antenna, Oksana Manzhura Dec 1995

Gabor Expansion Of An Equivalent Dipole Antenna, Oksana Manzhura

Theses

The Gabor representation in the context of an aperture problem is an expansion of a radiated field in terms of a discrete set of linearly shifted and spatially rotated elementary Gaussian beams. The parameters that can be varied in this summation are the number of beams and corresponding beam widths. As the difficulty associated with the unique determination of the expansion coefficients was alleviated, the method has been successfully applied to one and two dimensional apertures. Although, the asymptotic evaluation of expansion functions has reduced the computational burden drasticallym it was at the expense of some loss in accuracy. The ...


Small Computer System Interface (Scsi) Universal Services For The Turbonet Parallel Computer, Artak Ohan Melkonian Dec 1995

Small Computer System Interface (Scsi) Universal Services For The Turbonet Parallel Computer, Artak Ohan Melkonian

Theses

TurboNet is a parallel computer with shared-memory and message-passing hybrid architecture. It employs two boards, with four digital signal processors (DSPs) each, and a host FORCE SPARC CPU-2CE board with a SCSI bus.

Software has been developed in this thesis to provide SCSI services to programs running on the DSPs. DSP programs can therefore fully control assigned SCSI devices at the SCSI command level. Transfer control modifiers ensure compatibility with most SCSI devices.

The software provides service for three SCSI access levels. The "su" SCSI universal device driver is built into the host computer's kernel and is a gateway ...


Configuring The Radial Basis Function Neural Network, Insoo Sohn Dec 1995

Configuring The Radial Basis Function Neural Network, Insoo Sohn

Theses

The most important factor in configuring an optimum radial basis function (RBF) network is the training of neural units in the hidden layer. Many algorithms have been proposed, e.g., competitive learning (CL), to train the hidden units. CL suffers from producing "dead-units." The other major factor Which was ignored in the past is the appropriate selection of the number of neural units in the hidden layer. The frequency sensitive competitive learning (FSCL) algorithm was proposed to alleviate the problem of dead-units, but it does not alleviate the latter problem. The rival penalized competitive learning (RPCL) algorithm is an improved ...


Linearly Tapered Slot Antenna, Luis Alberto Tumialan Dec 1995

Linearly Tapered Slot Antenna, Luis Alberto Tumialan

Theses

Design procedure for Linearly Tapered Slot Antennas (LTSA) has been developed and implemented using High Frequency Structure Simulator (HFSS) code based on a finite-element analysis.

A CAD study of two variations of a LISA based on either a stripline or a microstrip feed has been carried out. Circular and radial stubs have been considered in these designs for an antenna operating at 10 Ghz. LTSA on a Duroid substrate fed by a stripline has been designed to operate with better than 12 dB return loss. Fabricated antenna was characterized and had even a wider response than the CAD design. Radiation ...


Minimization Of Sum-Of-Conditional-Decoders Structures With Applications In Finite Machine Epld Design And Machine Learning, Sanof Mohamedsadakathulla Dec 1995

Minimization Of Sum-Of-Conditional-Decoders Structures With Applications In Finite Machine Epld Design And Machine Learning, Sanof Mohamedsadakathulla

Dissertations and Theses

In order to achieve superior speed in sequencer designs over competing PLD devices, Cypress brought to market an innovative architecture, CY7C361. This architecture introduced a new kind of universal logic gate, the CONDITION DECODER (CDEC). Because there are only 32 macrocells in the chip, saving only one CDEC gate can be quite important (the well-known "fit/no-fit problem"). A problem that is related to the fitting problem of the Cypress CY7C361 chip is the SOC Minimization. Due to the limited low number of macrocells in CY7C361, a high quality logic minimization to reduce the number of macrocells is very important ...


Equivalent Relationship Of Function-Level Representation And Implementation Of Unified Indexing Of Fft Algorithms, Nee-Hua Cho Nov 1995

Equivalent Relationship Of Function-Level Representation And Implementation Of Unified Indexing Of Fft Algorithms, Nee-Hua Cho

Dissertations and Theses

With the advance of the VLSI technology, the FFT algorithm has been pushed further in solving the multidimensional array signal processing in real time. Many DSP chip users have tried to find ways to improve addressing huge data in multidimension systems with minimum cost and maximum performance. However, there is no efficient method to address data for 1-D to M-D FFTs. A methodology has been defined to conquer the addressing problem ofM-D FFT. It is well known that the twiddle factor matrix of Discrete Fourier Transform (DFT) can be recursively factored into basic butterfly stage matrices. The matrix can be ...


Performance Evaluation Of Specialized Hardware For Fast Global Operations On Distributed Memory Multicomputers, Rajesh Madukkarumukumana Sankaran Oct 1995

Performance Evaluation Of Specialized Hardware For Fast Global Operations On Distributed Memory Multicomputers, Rajesh Madukkarumukumana Sankaran

Dissertations and Theses

Workstation cluster multicomputers are increasingly being applied for solving scientific problems that require massive computing power. Parallel Virtual Machine (PVM) is a popular message-passing model used to program these clusters. One of the major performance limiting factors for cluster multicomputers is their inefficiency in performing parallel program operations involving collective communications. These operations include synchronization, global reduction, broadcast/multicast operations and orderly access to shared global variables. Hall has demonstrated that a .secondary network with wide tree topology and centralized coordination processors (COP) could improve the performance of global operations on a variety of distributed architectures [Hall94a]. My hypothesis was ...


Performance Analysis Of A Banyan Based Atm Switching Fabric With Packet Priority, Zhaohui Yan Oct 1995

Performance Analysis Of A Banyan Based Atm Switching Fabric With Packet Priority, Zhaohui Yan

Dissertations and Theses

Since the emergence of the Asynchronous Transfer Mode ( A TM ) concept, various switching architectures have been proposed. The multistage interconnection networks have been proposed for the switching architecture under the A TM environment. In this thesis, we propose a new model for the performance analysis of an A TM switching fabric based on single-buffered Banyan network. In this model, we use a three-state, i.e., "empty", "new" and "blocked" Markov chain model to describe the behavior of the buffer within a switching element. In addition to traditional statistical analysis including throughput and delay, we also examine the delay variation. Performance ...


Atomic Broadcast In Heterogeneous Distributed Systems, Osman Zeineldine Oct 1995

Atomic Broadcast In Heterogeneous Distributed Systems, Osman Zeineldine

Computer Science Theses & Dissertations

Communication services have long been recognized as possessing a dominant effect on both performance and robustness of distributed systems. Distributed applications rely on a multitude of protocols for the support of these services. Of crucial importance are multicast protocols. Reliable multicast protocols enhance the efficiency and robustness of distributed systems. Numerous reliable multicast protocols have been proposed, each differing in the set of assumptions adopted, especially for the communication network. These assumptions make each protocol suitable for a specific environment. The presence of different distributed applications that run on different LANs and single distributed applications that span different LANs mandate ...


Construction And Characterization Of An Extended Helicon Plasma Source, Russell Ford Jewett Jr. Sep 1995

Construction And Characterization Of An Extended Helicon Plasma Source, Russell Ford Jewett Jr.

Electrical and Computer Engineering ETDs

A new helicon source has been developed for plasma processing applications. The source is a modification of the traditional cylindrical helicon source design to rectangular geometry. In order to accomplish this, the antenna used for launching helicon waves is stretched in the direction perpendicular to the static magnetic field lines. This source was coupled to a long rectangular slab chamber which is used for the actual material processing. A static magnetic field of -200 Gauss peak strength, pointing out from the source into the diffusion region, was applied to facilitate helicon wave propagation. 13.56 MHz rf power was used ...


Mobility Modeling And Simulation Of Soi Si1-X Gex P-Mosfet, Sida Zhou Aug 1995

Mobility Modeling And Simulation Of Soi Si1-X Gex P-Mosfet, Sida Zhou

Dissertations and Theses

With increasing demand for complex and faster circuits, CMOS technologies are progressing towards the deep-submicron level. Process complexity increases dramatically, and costly techniques are to be developed to create dense field isolation and shallow junctions. Silicon-On-Insulator (SOI) may solve some of these problems. On the other hand, strained Si 1_xGex layers have been successfully grown on Si substrates and demonstrated much higher hole mobility than bulk Si. This can be used to build high-mobility p-MOSFET with a buried Si 1_xGex channel. A high mobility p-MOSFET would improve both the circuit speed and the level of integration. The purpose of the ...


Data Allocation For Distributed Programs, Liono Setiowijoso Aug 1995

Data Allocation For Distributed Programs, Liono Setiowijoso

Dissertations and Theses

This thesis shows that both data and code must be efficiently distributed to achieve good performance in a distributed system. Most previous research has either tried to distribute code structures to improve parallelism or to distribute data to reduce communication costs. Code distribution (exploiting functional parallelism) is an effort to distribute or to duplicate function codes to optimize parallel performance. On the other hand, data distribution tries to place data structures as close as possible to the function codes that use it, so that communication cost can be reduced. In particular, dataflow researchers have primarily focused on code partitioning and ...


Scaling Of The Silicon-On-Insulator Si And Si1-Xgex P-Mosfets, Marijan PeršUn Aug 1995

Scaling Of The Silicon-On-Insulator Si And Si1-Xgex P-Mosfets, Marijan PeršUn

Dissertations and Theses

Two-dimensional numerical simulation was used to study the scaling properties of SOI p-MOSFETs. Based on the design criteria for the threshold voltage and DIBL, a set of design curves for different designs was developed. Data for subthreshold slope, SCE and threshold voltage sensitivity to silicon film thickness are also given. Results show that short-channel effects can be controlled by increasing the doping level or by thinning the silicon film thickness. The first approach is more effective for p+ gate design with high body doping, while the second approach is much more effective for n+ gate design with low body doping ...


Seasonal Hidden Markov Models For Stochastic Time Series With Periodically Varying Characteristics, Arthur M. Lewis Jul 1995

Seasonal Hidden Markov Models For Stochastic Time Series With Periodically Varying Characteristics, Arthur M. Lewis

Dissertations and Theses

Novel seasonal hidden Markov models (SHMMs) for stochastic time series with periodically varying characteristics are developed. Nonlinear interactions among SHMM parameters prevent the use of the forward-backward algorithms which are usually used to fit hidden Markov models to a data sequence. Instead, Powell's direction set method for optimizing a function is repeatedly applied to adjust SHMM parameters to fit a data sequence. SHMMs are applied to a set of meteorological data consisting of 9 years of daily rain gauge readings from four sites. The fitted models capture both the annual patterns and the short term persistence of rainfall patterns ...


Modeling And Development Of A Cellular Micro-Kernel, K. Balaji Jun 1995

Modeling And Development Of A Cellular Micro-Kernel, K. Balaji

Master's Theses

A novel cellular load distribution strategy was designed and implemented on transputers by Dr. Richard Taylor and Dr. Don Goodeve at the University of York, United Kingdom. Based upon the above proposed strategy, a statistical model was developed using the Cellular Automata Theory. The theoretical model drives the implementation process of the cellular micro-kernel on the nCUBE 2S system. The load distribution and the performance characteristics for snake and L type transmission modes, and for uniform and non-uniform distribution of destination processors of the micro-kernel has been measured and compared with our theoretical model. The results show good agreement between ...


Grain-Size Optimization And Scheduling For Distributed Memory Architectures, Jing-Chiou Liou May 1995

Grain-Size Optimization And Scheduling For Distributed Memory Architectures, Jing-Chiou Liou

Dissertations

The problem of scheduling parallel programs for execution on distributed memory parallel architectures has become the subject of intense research in recent, years. Because of the high inter-processor communication overhead in existing parallel machines, a crucial step in scheduling is task clustering, the process of coalescing heavily communicating fine grain tasks into coarser ones in order to reduce the communication overhead so that the overall execution time is minimized.

The thesis of this research is that the task of exposing the parallelism in a given application should be left to the algorithm designer. On the other hand, the task of ...


Radiation Damage Studies In Gate Oxides, Sandeep G. Bharathi May 1995

Radiation Damage Studies In Gate Oxides, Sandeep G. Bharathi

Theses

Detailed investigation of the effects of Gamma-ray irradiation on the electrical properties such as current-voltage arid capacitance-voltage characteristics in thermally grown SiO2 films in the thickness range of 15 to 120 nm on silicon substrates is presented in this thesis. The structures used in this study are Al/Poly/SiO2/Si/Al and Al/SiO2/Si/Al MOS capacitors. Based on the electrical characterization studies, we observe that irradiation causes generation of positive charges in the oxide leading to a shift of the high frequency Capacitance-Voltage (C-V) curves. An increase in surface state density at the SiO ...


A Defect Detection Algorithm For Sequential And Parallel Computers, Ralf Hross May 1995

A Defect Detection Algorithm For Sequential And Parallel Computers, Ralf Hross

Theses

The comparison of images containing a single object of interest, where one of them contains a model object, is frequently used for defect detection/identification. This is often a problem of interest to industrial applications. To make this task more efficient, the implementation on parallel computers should be a major objective. This thesis introduces sequential and parallel versions of an algorithm that compares original(reference) and processed images in the time and frequency domains. The emphasis is on parallel implementation. This comparison may help to detect changes in images. Extracted data is also compared to database data in an attempt ...