Digital Commons Network^™

An Intelligent Electrocardiogram Tutoring Package Ekgchallenger, Santosh K. Ananthraman

Theses

This thesis presents the development and implementation of an intelligent electrocardiogram tutoring package, namely, EKGCHALLENGER which is meant for use in medical schools to teach medical students a method of diagnosing electro cardiograms.

EKGCHALLENGER is an IBM - PC based, user friendly package. It works in two basic modes. The first is a tutorial mode wherein the user is taught the step-by-step diagnosis of electrocardiograms ( EKGs ) which are presented in order of increasing difficulty. The second is the challenger mode wherein the user is asked to diagnose EKGs which are randomly chosen from an EKG database. The diagnosis …

Implementation Of The Sliding Dictionary Data Compression Algorithm On An At&T Dsp 32 Digital Signal Processor, Shu Fang

Theses

Compared with other data compression algorithms, the sliding dictionary is more practical for implementation in hardware. After a comprehensive study of the algorithm, an on line data compression scheme which uses AT&T DSP 32 Digital Signal Processor has been developed. Assembly language programs for encoder and decoder have been written and tested. The whole compression system has been simulated in a real-time environment and results have been obtained. A quantized coding scheme has been used to increase compression ratio. Separate assembly language programs have been written to implement the quantized coding scheme and tested. Results obtained from real-time simulation are …

Adaptive Subband Video Coding With Motion Compensation, Manjunatha S. Kadur

Theses

An efficient scheme for video sequence coding is presented here. The interframe redundancy present in the video sequence is exploited by motion compensation using the efficient independent orthogonal search technique, which requires least number of computations in the worst case. The motion compensated frame difference signal is encoded with a new technique — subband adaptive vector quantization.

Subband coding like transform coding results in signals of unequal energy patterns, which is efficiently utilized for bit allocation. In addition, the subband approach offers means for efficient (but suboptimal) Vector Quantization (VQ) by splitting the signal into several signals. By rate distortion …

Csma/Cd Lan Performance : Modeling And Simulation In Csim, Nanda K. Kanuri

Theses

A simulation model to analyze the performance of CSMA/CD protocol is developed. CSIM, a process oriented simulation language, is used. Performance measures such as throughput, average delay and maximum delay per packet are presented. System performance is analyzed for different loads, number of stations, and network lengths, with packet length as parameter. By trading off the throughput and delay time, an optium packet length can be selected from simulated performance curves. A general scheme for MAC protocols modeling is provided.

Distributed Data Collection System Based On Hierarchical Network, Harish Mahindrakar

Theses

On line data collection systems are essential in order to satisfy the requirements for real-time applications. Typical applications are computer integrated manufacturing, security control, hourly wage calculations, human resources management. On line data collection system makes it possible to closely monitor and track different operations with more accuracy. On line data collection systems eliminate redundant work, save time and money.

If the distributed system is based on a multicontroller, it becomes really cost effective solution to build such a system.

This effort is the design of a distributed multicontroller system, required in a data collection system. A hierarchical network is …

Trellis Encoded M-Ary Partial-Response Schemes, Raju P. Patel

Theses

Convolutional codes can be used to improve the reliability of partial-response channels in a Gaussian noise environment. Multilevel partial-response schemes can be used to increase the information rate in a given bandwidth compared to binary partial-response schemes. This thesis deals with the theory and construction of convolutionally encoded 4-ary partial- response schemes. The free Euclidean distance of the combined trellis of rate-1/2 convolutional code and 4-ary partial-response scheme is found through a computer search, using the Viterbi-algorithm.

The matched encoding concept is also applied to find the conditions for matched encoding for combined trellis of rate-1/2 convolutional codes and 4-ary …

Hardware And Software Designs For Integrated Electrical Engineering Experiments, Sujin Pramojaney

Theses

The interfacing between the various electrical engineering fields is not emphasized in the electrical engineering laboratory; the traditional aim of a laboratory course is to complement a single theoretical course. The object of this thesis is to provide means, hardware and software, that can be used in different system configurations to perform useful industrial tasks. The chosen task is to control electrical machines using a microcomputer. Experiments can be written to be performed by students, using these systems. The emphasize of these experiments can be on the characteristics of a power electronics device, but the device will be seen as …

Network Realizability Approach To Robust Stability Of Discrete-Time Systems Characterized By Polynomials, Sri Indran Rasiah

Theses

In system design, the coefficients of a characterizing polynomial are usually not precisely known but can be bounded from above and below by real numbers. The requirement of robust system design from the stability standpoint demands, then, the guaranteeing of the stability of a set of polynomials.

Stability theorems for continuous-time systems and discrete-time systems, are studied in this report. It is shown that one more condition has to be included into each of the theorem. The revised theorem for continuous-time systems is proved through network realizability theory. The one for discrete-time systems is, then, proved via the use of …

Design Of Governor-Turbine Models In Stability Studies, Vidyanand Swaminathan

Theses

This thesis investigates the effect of hydro governor-turbine models on the steady state stability of an automatically controlled electric power system. Basically two kinds of hydro governor-turbine models, namely, Impulse and Francis type are studied in depth. Design of a compensating network has also been proposed, which can help improve the stability conditions of a power system which employs a poor governor-turbine model.

The power system investigated includes a large sized hydro generating unit connected to an infinite bus via a power network. This generator employs a modern three-channel fast-acting automatic voltage regulator (AVR). For any operating condition, stability results …

Analysis On Dielectric Resonators, Xuan Tu

Theses

This dissertation deals with the studies and analysis of Dielectric Resonators (DR). A shielded dielectric iesonator structure, consisting of the substrate, the spacer, the dielectric resonator and the metallic shielding is modelled theoretically. The theoretical expressions for the resonance fields are derived by using radial-mode matching and axial mode-matching techniques. In these techniques, the structure is divided into partial regions and the fields in each pai tial region are represented in terms of a series of the appropriate modes with unknown coefficients. Matching the adjacent regions yields a system of linear or nonlinear equations — which then are solved. The …

Nonlinear Variants Of The Least Mean Square (Lms) Algorithm, John George Van Saders

Theses

Adaptive systems using the LMS algorithm or its variants usually require bilinear correlation multipliers with high dynamic range and large bandwidth. The class of LMS-type algorithms utilizing zero-memory limiters (on one or both correlation multiplier inputs) to reduce dynamic range are examined. The correlator limiters may be included to simplify the hardware implementation or may arise due to limited dynamic range of the loop components. The application of a theorem due to Price provides a technique for simplifying the analysis, which otherwise might be extremely difficult. The analysis provides closed-form expressions for the mean weight convergence behavior, permitting examination of …

Arithmetic Pipeline Analysis Package Ii, Sai K. Vedantam

Theses

This work describes the implementation of arithmetic pipeline scheduling algorithms, to enhance an existing simulation package. The user need only specify the arithmetic equations to be processed and the required stage configuration. The program automatically performs the tasks of forming the reservation table, building the pipeline and specifying the input/output connectivity for each segment and multiplexer in the pipeline. This package integrates two existing simulation tools and enhances many aspects of the previous programs.

The main application area for such a tool is education. Since it is very easy to use and requires little or no time for one to …

Caldac, A New Approach To Computer-Assisted Theatrical Lighting Design, David William Zalewski

Theses

CALDAC, which stands for Computer-Assisted Lighting Design and Control, is a design environment integrating two present day state-of-the-art theatrical lighting computer aides, the computer-aided design (CAD) program and the preset storage system. The CALDAC environment also features On-Screen Stage Simulation, a newly proposed design tool. It is shown that this integration offers a strong advantage to the lighting designer and his/her crew.

The thesis begins by introducing the concepts of theatrical lighting design and the evolution of computerized control. The basics of CAD for the lightplot design are presented, followed by an introduction to the concepts of on-screen stage simulation. …

Rays And Beams Near The Shadow Boundary, Weixing Gao

Theses

Asymptotic techniques in wave propagation problems exhibit attractive features in computational aspects compared to numerical methods. However, they experience problems in complicated environments due to the transition regions associated with them. The transition region involving a shadow boundary in the downward refractive index profile has been investigated. The ray paths were determined solving the ray equation analytically. The Green's function due to a line source is constructed and evaluated using numerical integration (reference solution) and asymptotic techniques. Then, the field produced by the source, is synthesized, using superposition of beams generated from complex source point representation. The floating parameters such …

Schottky-Barrier Solar Cells, Surface Patterning For Efficient Light Collection, Constantinos Manolis

Theses

Different geometrical surface configurations are considered here for a Au/n-Si semiconductor Schottky-barrier solar cell to improve their light collection efficiency.

Optical and electrical properties are theoretically analyzed for two given optical wavelengths of 0.9 and 0.5 micrometers respectively.

The configurations considered are: V-shaped, Star- shaped, M-shaped, asymmetric-V-shaped, and asymmetric-M-shaped. They all show a significant improvement in the short-circuit current over a flat cell model, while the open-circuit voltage remains practically unchanged.

User Interactive Compensation For Si/So Systems Via Root-Locus, Shih-Mim Liu

Theses

A powerful computer-aided root-locus method is described and applied to the compensation for SI/SO systems. The approach is based on the concept of continuation methods in which the solution of a parameterized family of algebraic problems is converted into the solution of a differential equation and incorporates the quadratic synthetic division technique. The root-locus is obtained in a systematic manner by numerical integration. Breakaway points are analyzed and classified according to the properties of higher order derivatives. A Turbo Pascal(4.0) program which utilizes the algorithm has been written.

Trellis Coded Partial-Response Channels, Kumari Yalamanchili

Theses

Binary partial-response channels with transfer functions (1+D), (1-D) and (1 — D²) are intersymbol-interference channels which find applications in baseband data communications and magnetic recording systems (tapes, discs, compact discs, etc.). In this thesis we develop a coding technique for improving the reliability of digital transmission over noisy partial-response channels with the above transfer functions. We do so by introducing a new concept, called matched encoding, which arises in the context of trellis coding for channels with memory.

We use inner and outer trellis coding of the partial-response channels. The inner codes called matched inner coset codes, are …

Methods Of Achieving High Speed On Data Flow Machines, Chung-Lin Yu

Theses

Simultaneity is a key to high speed and large computation. Assuming hardware components of a given speed, it is the only remaining consideration in achieving raw speed. Simultaneity can be shackled by dependencies, however, and years of hardware and software work have been devoted to understanding the types of dependencies and how they can be obeyed or removed from a computation.

In this thesis, the principles of the data flow machines and the structure of the data flow languages are illustrated. Various methods of achieving high speed are discussed. These methods include streams, Lenient Cons (I-structure), and dependence-driven computation, which …

Unified Study Of Trellis Encoded Correlative-Fm, K. Narendra Bhat

Theses

Trellis encoding of correlative-FM is studied from the point of view of the overall structure, performance, bandwidth occupancy, and complexity. Here, correlative (partial-response) coding is used to improve the bandwidth efficiency of MSK (Minimum-Shift Keying) at the expense of performance. Then, trellis codes are used to improve the error-rate performance of the corresponding correlative-FM scheme with little or no increase in bandwidth occupancy (compared to uncoded MSK). In a sense, this is similar to Ungerboeck's coding for (memoryless) PSK modulation.

A new encoding approach, called matched encoding, is used here that produces trellis coded modulations achieving greater coding gains than …

A Cmos Robotic Lan Interface Integrated Circuit Design, Yong-Bin Kim

Theses

This thesis describes the design including specification, schematics,logic and circuit simulation, and standard cell layout for a CMOS mixed-mode I.C. for interfacing sensors into a robotics local area network. The network accepts up to 256 interface chips as nodes in each area. A simple network protocol permits acquisition of digital data from the interface nodes through gateways into ARCNET and MAP.

The sensor chip interfaces directly from analog signals of range 0-1V and 0-20mV. It contains an 8-bit ADC. The application I.C. interfaces to sensors for pressure, tactile stress, humidity, temperature, etc.

Each of the sensor interface node I.C.s is …

Nonlinear, Metal-Clad Optical Waveguide, Bhavesh Patel

Theses

Planar optical waveguides consisting of different types of films including nonlinear films with metal cladding have been studied theoretically. Ideal metal cladding with σ = ∞ and nonideal metal cladding with σ ≠ ∞, that is, with complex refractive index is considered to get electric field and wave number for TE₀ mode. For nonlinear material, approximate solution is derived in a series form using Rayleigh-Schrodinger method. The appropriate eigenvalue equations are solved by Newton-Raphson iteration method. For self-focusing media in the center, the propagation constant increases with increasing power and with self-focusing media in the cladding the propagation constant …

Spectrum Analysis Of Heart Rate Variability, Xuming Wang

Theses

This research investigated the respiratory influence on heart rate variability. The heart rate spectrum was obtained from the heart rate variability signal which was extracted from the electrocardiogram We then studied the magnitude of the respiration peak in the heart rate spectrum and examined the dependence of the magnitude of this peak on breathing frequency, subject and day.

An experiment designed to simultaneously acquire the electrocardiogram and the respiration signal was conducted on ten people ranging from 22 to 55 years of age (3 females, 7 males). Three tests were performed on each subject. In each test, 2 different postures …

Statistical Multiplexing Of Video Sources For Packet Switching Networks, Krishna Kancherla

Theses

Communication networks are fast evolving towards truly integrated networks handling all types of traffic. They employ integrated switching technologies for voice. video and data. Statistical or asynchronous time division multiplexing of full motion video sources is an initial step towards packetized video networks. The main goal is to utilize the common communication channel efficiently, without loosing quality at the receiver. This work discusses the concept of using statistical multiplexing for packet video communications. The topology of a single internal packet network to support ISDN services has been adopted. Simulations have been carried out to demonstrate the statistical smoothing effect of …

An Evaluation Of The Plasma Frequency Probe, Charles Merrill Swenson

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Electron density in a plasma can be measured by determining the plasma frequency. For 20 years this electron density measurement technique has been used with the plasma frequency probe. The purpose of this paper is to characterize, evaluate, and suggest improvements for this instrument. Although the current plasma frequency probe is a highly successful instrument for measuring absolute electron density in the ionosphere, several areas for improvement were found. These were in the radio frequency head and the voltage controlled oscillator. Currently, the plasma frequency probe is approximately 20% accurate in determining absolute densities around 1.5x10⁴ electrons/cm³ but …

Convergence Properties Of The Waveform Relaxation Method As Applied To Electric Power Systems, Marija D. Ilić, J. K. White, Mariesa Crow

Electrical and Computer Engineering Faculty Research & Creative Works

Several theoretical results are presented and simple examples examined in order to determine the suitability of waveform relaxation for transient power system simulation. This examination leads to two practical suggestions that can easily be satisfied for power systems. The first is to break the simulation interval into sections, the first of which should be narrow and be used to kill off errors in the initial guess that activate the stiff modes. The second is to partition the system into subsystems that are stable, as this not only aids convergence but ensures multirate numerical stability.

Study Of Direct Semiconductor Materials For An Optically Controlled Switch, Sung Taek Ko

Electrical & Computer Engineering Theses & Dissertations

A model for a bulk GaAs photoconductive switch has been developed and solved to determine the performance of the device in closing and opening switch applications. The GaAs material has been characterized by deep level transient spectroscopy (DLTS). Two electron traps (EL2 and EL5) and one hole trap (Cu_B} have been detected and were included in the model. Simulation studies are performed on several GaAs switch systems composed of different combinations and density of deep levels to investigate the influence of deep traps in a photoconductive switch system. The electron occupancy of each deep trap is traced in …

A Methodology For Designing Spacecraft Onboard Processing Systems, Mohammad Nadeem Ahmad

Theses

A three layer methodology is presented for designing spacecraft onboard computer systems. The system design is perceived as a sequence of three hierarchical layers: the Dedicated Processing Layer, the Application and Support Processing Layer, and the Communications Processing Layer. Each layer implements a distinct set of functions and offers services at different levels of abstraction. As opposed to the ISO/OSI Reference Model, where the prime objective is to implement peripheral interaction between two systems, the layered approach used here is to address the problems in system design itself. The problem is approached in a bottom-up fashion, starting with the description …

A Microcomputer Based Non-Invasive Cardiopulmonary Monitor Using A Microwave Interferometer, Tanmoy K. Basu

Theses

With a microwave interferometer the vibrational velocity of the anterior (front), as well as posterior (back) chest wall can be monitored and recorded. The recorded signals are a reflection of the mechanical cardiac activity within the chest cavity, as opposed to Electrocardiogram (ECG) which is a reflection of the electrical cardiac activity. The interferometer recordings are obtained with no physical contact between the instrument and the subject. Moreover, the subject can be fully clothed since microwave energy readily passes through normal dry clothing.

A microwave interferometer that is capable of detecting the vibrational velocity of the surfaces of the chest …

Microprocessor-Based Processing Unit Implemented By Xilinx Programmable Logic Array, Lee Chuan Hu

Theses

The 8052 microprocessor-based processing unit is a super single board computer with many unusual features: memory page selecting with page indicators, on-board EPROM/PROM programmer, real time clock, battery back-up RAM, and memory mapped I/O. It is implemented by using Xilinx programmable logic array and can be used for various instruments. Xilinx user-programmable Application-Specific Integrated Circuit (ASIC) is a large logic array with up to 9000 equivalent gates. The advantages of programmable logic devices over standard ICs are more flexibility, design security, lower cost, higher performance, reduced power consumption, smaller size, and increased reliability. The system development time is also greatly …

Reliability Problems And Failure Mechanisms In Ic Packaging, Dilip J. Patel

Theses

Today, reliability is acknowledged as an important item in design and operation of electronics circuits and system.

This thesis provides information on evaluation of the reliability for hermetic and non hermetic IC packages made by different manufacturers.

Literature study concentrates on the reliability and related problems in IC packages developed between 1970 and 1988.

Several failure mechanisms and failure modes are discussed to point out how higher reliability in IC packages may be achieved.

The bibliography is given in a chronological order to help further research in this area.