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Improving Solids Conveying In Plasticating Extruders : An Investigation Into Manufacturing Processes And Manufacturing Systems For Profiled Thermoplastic Pellets, Oommen Cherian

Theses

The objective of the thesis is the manufacture of thermoplastic bilobal and trilobal profiled pellets for the determination of the interparticulate co-efficient of friction exhibited by solid beds of such pellets. The enhancement of the interparticulate coefficient of friction is expected to lead to ameliorated solids conveying rates in plasticating extruders.

Predicting the product shape from a profile die is very difficult due to the elastic memory of plastics and the complex boundary conditions. Consequently the cost involved in experimenting with different profile dies is high. Therefore a standard die with several die inserts of varying cross-sections were used to …

Effect Of Moisture On Microcircuit Failure, Chandrabala D. Patel

Theses

Stability and reliability of microcircuit is dependent on its design, fabrication, testing, storage and use.

In this thesis emphasis is given on various failure mechanisms of Integrated Circuits in humid environment and techniques of improving reliability. Other factors which affect the failure of integrated circuits are also discussed. Moisture induced failure modes, semi-reversible failures and irreversible failures (surface leakage current and corrosion-causing interruption of interconnection lines) are also reviewed.

Controlling the contaminants and moisture related corrosion are also covered. The quickest way to evaluate the reliability of microcircuit is by accelerated aging test and by selection of meaningful criteria of …

Properties And Device Applications Of Hydrogenated Amorphous Silicon Carbide Films, M. Mahmudur Rahman, Cary Y. Yang, D. S. Sugiharto, A. S. Byrne, M. Ju, K. Tran, K. H. Lui

Electrical and Computer Engineering

Hydrogenated amorphous silicon carbide (a‐SiC:H) films were deposited with a radio‐frequency plasma‐enhanced chemical vapor deposition system which utilizes a dc electric field applied independently of the inductively coupled rf field. The source gases were SiH₄ and CH₄. It was found that application of an electric field directed out of the substrate surface enhances the growth rate and yields some improvements in photoconductivity. The compositions of the films were evaluated by x‐ray photoelectron spectroscopy for a range of source gas mixtures. In order to assess the applicability of a‐SiC:H thin films, heterojunction a‐SiC:H/crystalline Si (c‐Si) diodes were fabricated …

Coke Oven Emissions: A Case Study Of Technology-Based Regulation, John D. Graham, David R. Holtgrave

RISK: Health, Safety & Environment (1990-2002)

After examining and analyzing the experience with coke ovens, the authors conclude that attempts to force technology beyond its demonstrated competence can be both expensive and ineffective in controlling hazards. They also suggest implications for pending proposals to further control air pollution.

Computer Aided Localization Of Neurological Diseases, Yusuf Parlar

Dissertations

Computers in medicine has brought new dimensions and better understanding of uncertainties in the field of medical sciences in the last decade. This thesis is focused upon the localization of neurological lesions in the human nervous system. It relates clinical neurological test outcomes to pathways of function or malfunction. Certain methods are proposed-empirical. stochastic. Deterministic-to estimate the spatial distributions of lesion probabilities.

First. a Bayesian model is presented to estimate the posterior probability of lesion from a priori information, based on the test outcomes. Due to unavailable data alternative methods and models are presented: Regression Analysis. Monte Carlo simulation, and …

Computer Modeling And Analysis Of Biological Rhythms, Shi Xiong Yang

Dissertations

Biological rhythms are an important phenomenon and feature of physiologic systems. Indirect means have to be employed for their description and exploration due to the unclear internal nature of the system. This study analyzed and developed several possible mathematical models using single or multidimensional nonlinear differential equations to approach the experimental circadian data. The numerical solutions of the models were obtained by computer simulation and the simulated and experimental acquired circadian data were analyzed in both the time and frequency domains. Phase plane plots, phase response curves and power spectrum analysis were employed to determine the nonlinearity of the system …

Interconnection Of X.25 Networks, Syed Ayaz Qutubuddin Ahmed

Theses

The purpose of this work was to investigate the performance of two interconnected X.25 networks via CCITT internet protocol X.75. Since internet protocol X.75 follow the same flow approach as X.25, we are allowed to model the acknowledgement queue in such a way that this queue provides a feed back path from destination to the source queue. Thus we are able to model our interconnected network as a closed queueing network with limited number of packets in transit within the network. Mean Value Analysis with Blocking (MVA) algorithm was applied to obtain the performance characteristics as the resources available were …

An Implementation Of Mht Algorithm For Adaptive Transform Coding Of Speech, Peter Battenschlag

Theses

The Modified Hermite Transform (MHT), a suboptimum block transform scheme, is implemented on a TMS320C25 signal processing system with the objective of reducing the redundancy in speech signals and transmit a quantized vector representation at bitrates as less as 0.5 bits per sample.

The generation of the Hermite polynomials with a binomial and several first order IIR filter structures is presented focusing on the fact that no muliplications are required which simplifies the MHT algorithm considerably.

An assembler program performs forward and inverse transformation together with a vector quantization using adaptive bitallocation based on short-time statistics for the transform coefficients. …

A Micro-Based Machine Vision System, Hsueh-Chung Michael Feng

Theses

In this thesis, a low-cost general purpose machine vision system based on a personal computer of the PC-XT/AT family and an electronic camera controller based upon a Motorola 6811C11 single-chip microcontroller has been designed and implemented. This work is focused on image formation. The system supports a long distance camera-computer configuration. A picture editor, generic image manipulation software was designed and implemented. A single computer can supervise multiple cameras.

Reliability Of Titanium Dioxide Capacitors, Md. Badrul Hasan

Theses

In recent years many different materials have been investigated as potential thin-film capacitor dielectrics. Silicon monoxide (SiO) and tantalum pentoxide (Ta₂O₅) are the two dielectric materials that are being used by most companies.

This thesis provides some theory and experiments to evaluate the reliability of TiO₂ as a material which would yield a dielectric constant much higher than Ta₂O₅. It has also been shown that titanium dioxide is economically and technically capable of miniaturization demanded by the latest electronic systems.

Included here are the sections covering evaporant materials and their purities, …

An Artificial Neural Network For Redundant Robot Inverse Kinematics Computation, Wibawa Utama

Theses

A redundant manipulator can be defined as a manipulator that has more degrees of freedom than necessary to determine the position and orientation of the end effector. Such a manipulator has dexterity, flexibility, and the ability to maneuver in presence of obstacles. One important and necessary step in utilizing a redundant robot is to relate the joint coordinates of the manipulator with the position and orientation of the end-effector. This specification is termed as the direct kinematics problem and can be written as x = f(q)
where x is a vector representing the position and orientation of the end-effector, q …

Design And Analysis Of Movable Boundary Allocation Protocol, Karun Sekhri

Theses

The increasing digital communications traffic will require very high speed networks. The use of high communication speed increases the ratio between end to end propagation delay and the packet transmission time. This increase causes rapid performance deterioration and restricts the utilization of the high system bandwidth in broadcast channel based systems. Using several parallel channels in place of a single channel improves this ratio. For a given system bandwidth the total system capacity is increased by bandwidth division and parallel communication. FTDMA protocols have been suggested for the parallel channel network and these protocols are suitable for different loads. In …

Control Of Stress In Silicon Nitride Thin Films, Ajay Krishnan

Theses

Silicon nitride thin films of varying composition and thickness were deposited on silicon substrates by reactive rf diode sputtering of a silicon target using an argon/nitrogen gas mixture. Film stoichiometry could be controlled by varying the partial pressure of nitrogen, the total sputtering gas pressure and the target rf power. Films with refractive index of 2.01, the value for stoichiometric silicon nitride, could be obtained. Film stress was measured by wafer curvature; refractive index and thickness of deposited films were obtained by ellipsometry and interferometry measurements. The etch rate in buffered HF for films with refractive index 2.05 was 29A/min; …

Multiprocessor System Design Tutor : Expert System Approach, Rakesh Kamdar

Theses

To increase computational bandwidth and system resilience, integration of several microprocessors in a single system becomes necessary. The overall throughput and efficiency of such a system is directly dependent on the hardware and software interconnection supported by the basic microprocessor chip. Sometimes it becomes difficult to put together all the information for design criteria and all the design related formulas.

The approach made here is to continuously update the hardware and software information in the database related to a given microprocessor. This information can be accessed at any time for efficient design solution. Intel 80386 and Motorola 68020 microprocessors are …

Design Of A Real Time Optical Sensor For Continuous Blood Cell Separation, Girish S. Yerande

Theses

For continuous measurement and display of oxygen saturation and RBC content in blood during cell separation a reflection type optical sensor is designed based on the theoretical model using the photon diffusion theory. The prototype sensor consists of two arrays of light emitting diodes, red and infrared, and photodiodes. The emission wavelength of LEDs are 660 nm and 800 nm. The 800 rim which is in the infrared region is very close to isobestic value for blood. The prototype sensor is mounted on the blood cell separator equipped with an antitwister mechanism. Each LED emits a specific wavelength of light …

Trellis Coded Tamed Frequency Modulation In Rayleigh Fading Channels, Kiran R. Patel

Theses

It is usually difficult to reduce the effects of channel impairements on transmitted information. A fading channel is one such media in which digital communications system operates. A signal is subject to distortion in amplitude and phase when propagating towards the receiver. This puts constraint in required SNR at the receiver, for given performance. Various modulation/coding and demodulation/decoding techniques are employed to lessen the effects of fading. Bit error rate is a performance parameter that sets the criteria for signal design, system architecture and performance.

Here, a slow Rayleigh fading channel with three propagation paths possesing a scattering function of …

Lossless Image Data Compression Techniques Using High Order Markov Arithmetic Encoding, Santo Politi

Theses

It is difficult to compress digital images with acceptable ratios if a distortion is not acceptable. The lack of a rule based structure as in a language is one of the main reasons. In this work a number of algorithms for lossless image data compression are considered. The coding and the modeling aspects are treated separately. Different approaches are proposed to combine. Markov Arithmetic Encoding, a very efficient plain text encoding scheme, with source modeling algorithms to obtain higher compressibility. A modular approach is selected which enables combining various models. Model statistics are studied for further improvements. The schemes presented …

Single Token Integrated Dama In Multiple Bus Local Networks, Srinivasan Ramadurai

Theses

Multiple-bus local Networks (MBLNs) provide an architecturally simple solutions to serve high-reliability-high capacity local area networks(LAN) applications. Access mechanisms for MBLNs possessing stability and favorable delay characteristics are developed in this thesis. A new technique is proposed that uses a single explicit token to achieve demand assignment multiple access (DAMA) to arbitrate access on all the buses in the system. Analytical model was developed and compared to simulation results that indicates performance improvement in terms of delay characteristics of the system of buses.

Temperature Dependent Current-Voltage Characteristics Of Tisi2/N+/P Silicon Shallow Junctions, Bhupendra M. Shah

Theses

Analyses of temperature dependent current-voltage characteristics, of titanium silicide films on n+/p silicon shallow junctions, has been presented here. The fabrication technique involves the formation of shallow pn junctions, by ion-implantation of As+ through titanium films evaporated on P type silicon. The improvement of the activation of dopants has been fulfilled by different annealing processes in conjunction with the dopant drive-in. Electrical measurement of temperature dependent current-voltage technique has been employed to characterize these devices. The temperature dependent factors such as energy bandgap narrowing, majority carrier degeneracy, diffusivities, mobilities and minority carrier life time are evaluated by using key approximations.

Design And Analysis Of Microengineered Accelerometer, Nana Shigematsu

Theses

This master's thesis is about microengineered accelerometer integrated on a silicon wafer using two polysilicon layers acting as capacitors. This accelerometer operates as a capacitor sensor which is built between two polysilicon layers. It senses a difference of acceleration of gravity, or weight of the polysilicon beam. Both changes tend to change the capacitance between two layers, therefore, to change the resonant frequency of a resonant circuit built using this device and external inductors.

This master's thesis involves theoretical calculations of capacitor sensor for three sizes of capacitor area. Even though this sensor has not been fabricated yet, this sensor …

Multi-Sensor System For An Articulated Robot Hand, Narendra Sucahyo

Theses

The precision and dexterity of a manipulator hand critically depends on the proper extraction and processing of sensory information. This thesis describes how a sensor system equipped with fingertip sensors and strain gauges can provide proper feedback to drive the grasp kinematics of an articulated robot hand. The grasp kinematic that provide the manipulator hand with precision and dexterity is based on impedance control. The fingertip sensors and the strain gauges are constructed of piezoresistive materials for force transduction. Through optimization, based on the sensitivity and capability of the sensors, a synergism of force and contact information can be obtained …

A Study Of Signal Cancellation Effects In Adaptive Arrays, Cheng-Der Sun

Theses

An adaptive array can automatically place pattern nulls in directions from which undesired signals (interference, jamming, or clutter, etc.) arrive and can also provide gain for a desired signal. The purpose of this study was to study the effects of the adaptive array on the desired signal while suppressing the undesired signal.

This was done by studying the transfer characteristics of the adaptive array between its input and output. In this study, C.W. jammers along with the desired signal were considered and input and output relationship of the adaptive array were determined. Several basic types of adaptive arrays were studied …

Delay Improvement And Reliability Enhancement In A Cim-Based Factory Network, Vimalkumar Upadhya

Theses

Today, Computer-Integrated Manufacturing (CIM) refers to the integration of computer-controlled factory floor devices with engineering design and plant management computers. In general, there is a need for more efficient factory networks than are currently available. To this end, it is essential to investigate new network architectures and study their performance.

A number of CIM networks are analyzed in this thesis, and a new CIM network architecture is proposed. The throughput and delay characteristics of all these network architectures are derived from their respective simulation models. The results indicate that the proposed CIM network architecture has superior performance characteristics, compared to …

Temperature Dependent Current-Voltage Characteristics In Thin Sio2 Films, Jin Zhao

Theses

An analysis of the Fowler-Nordheim tunneling (FNT) theory and its application to temperature dependent current-voltage characteristics, of very thin films of SiO₂ on silicon, is presented. The final results are believed to provide the most complete examination of FN emission theory and predict the breakdown electric field in thin SiO₂ films. The role of the roughness, at the Si-SiO₂ interface, in determining the FNT current and breakdown mechanisms in metal-oxide-semiconductor (MOS) structures are also discussed.

Design And Processing Of Micromechanical Sensor Devices, Zhixiong Joe Zhou

Theses

A multi-purpose cantilever beam and microbridge accelerometer structure has been designed and fabricated in this work. This same structure with modification can be employed as a capacitive accelerometer, mechanical resonance accelerometer, and a piezoresist accelerometer. Surface microengineering processing techniques have been developed in this work. The cavity structure significantly reduced the parasitic capacitance. This work reports the first instance of spin-on glass for rnicromechanical device applications as both a sacrifical layer and a planarization material for the cavity. Other results of this thesis including:

1. LPCVD low temperature oxide as the base material from which the cavity is etched;

2. …

Cryogenic Characterization Of Potential High Temperature Superconducter Substrates At Microwave Frequencies, Sukhmani Kaur

Theses

The lack of characterization data for dielectric substrate materials at microwave frequencies and cryogenic temperatures hinders the development of high T_c superconducting circuits. Low loss (tanδ < 10^-4) substrates with dielectric constants in the range of 5-100 at cryogenic temperatures are needed to realize the advantages of superconductor circuits. Measurement techniques previously reported are either time consuming or inaccurate. We report an adaptation of Courtney's method for accurate, simple evaluation of complex dielectric constants (10 < ε_r < 100) at low temperatures. The fixture was calibrated using known properties of polycrystalline ZrSnTiO4. We measured er and tans on three potential substrate materials, Al₂O₃, MgO, and LaAlO₃ at 5-10 GHz in the temperature range 77-300K. No temperature hysteresis in either ε_{r …}

A Theoretical Model For Radio Attenuation Inside Buildings, Kyu-Sung Kim

Theses

Research to expand the capability of indoor, portable, radio frequency links for voice and data transmission is being pursued worldwide. Sophisticated communication systems using digital portable radio telephones have been proposed. To accomplish this goal, it is necessary to ascertain the attenuation of electromagnetic signal propagation inside buildings. Because modeling of the indoor environment at radio frequencies is very complicated, most publications document experimental results. In this study,. a theoretical model is proposed for predicting path loss inside buildings. The theory involves a waveguide model of the indoor environment which permits a rigorous modal solution similar to that developed by …

Design Of An Ionized Cluster Beam System For Thin Film Deposition And Cluster Size Measurement, Steven K. Krommenhoek

Theses

This thesis describes a study of a unique deposition technique known as Ionized Cluster Beam (I.C.B.) deposition. According to I. Yamada and T. Takagi, the inventors of the I.C.B. concept, the beam of deposited material contains clusters as large as thousands of atoms. To study the mass distribution of the ionized species, an I.C.B. source was designed and built by the author. The design provided temperature control along the axis of the crucible by using electron beam heating with two independently controlled emission filaments. Special attention was given to minimizing the background of charged particles generated in various sections of …

An Mcs Basic-52 Sbc Using Anything But An 8052ah-Basic, Hyunyeop Lee

Theses

This thesis exploits the ways to develop a new MCS BASIC-52 SBC using anything but an 8052AH-BASIC microcontroller. The 8052AH-BASIC based SBC offers short development time and low system cost; it is advantageous for numerous applications especially in the instrumentation, measurement and process control. However, the 8052AH-BASIC is no longer officially supported by INTEL and could disappear. Also, this SBC is not adequate for applications where power consumption is an important factor because the 8052AH-BASIC, a MOS product, draws a considerable amount of current.

To solve these problems we demonstrate how the 8052AH-BASIC can be replaced by any of a …

A Stereo Vision Technique Based On The Multi-Positioned Camera Criterion, Jie Bao

Theses

A modified feature based stereo vision [sic] technique is described in this thesis. The technique uses the curve-segments as the feature primitives in the matching process. The local characteristics of the curve-segments are extracted by the, Generalized Hough Transform.

A set of images of a scene, which are taken by a multi-positioned camera satisfying the parallelism criterion, are first filtered by the Laplacian of a Gaussian operator in different widths, i.e. coarse to fine channels. At each channel, the Generalized Hough Transform is applied to the curve-segments in each image. The curve position, the curve-length, the curve centroid, the average …