Engineering Commons^™

Incorporation Of Differential Global Positioning System Measurements Using An Extended Kalman Filter For Improved Reference System Performance, William J. Negast

Theses and Dissertations

To quantify the performance abilities of existing or proposed navigation systems, the U.S. Air Force has, for the last several years, compared the performance of the system under test to the performance of a baseline navigation system known as the Completely Integrated Reference Instrumentation System (CIRIS). CIRIS obtains a highly accurate navigation solution by combining information from three major subsystems: inertial navigation system (INS) information, barometric altitude information, and range and range-rate information from ground transponders which have been precisely surveyed. Although the navigation solution produced by CIRIS is highly accurate, it will soon be inadequate as the standard against …

An Investigation Of The Application Of Artificial Neural Networks To Adaptive Optics Imaging Systems, Andrew H. Suzuki

Theses and Dissertations

Recurrent and feedforward artificial neural networks are developed as wavefront reconstructors. The recurrent neural network studied is the Hopfield neural network and the feedforward neural network studied is the single layer perceptron artificial neural network. The recurrent artificial neural network input features are the wavefront sensor slope outputs and neighboring actuator feedback commands. The feedforward artificial neural network input features are just the wavefront sensor slope outputs. Both artificial neural networks use their inputs to calculate deformable mirror actuator commands. The effects of training are examined.

Direct Recovering Of Surface Structure Characterized By An Nth Degree Polynomial Equation Using The Uoff Approach, Mazen A. Salhi

Theses

There are two different approaches for estimation of structure and/or motion of objects in the computer vision community today. One is the feature correspondence method, and the other is the optical flow method [1]. There are many difficulties and limitations encountered with the feature correspondence method, while the optical flow method is more feasible, but requires a substantial amount of extra calculations if the optical flow is to be computed as an intermediate step.

Direct methods have been developed [2-4], that use the optical flow approach, but avoid computing the full optical flow field as an intermediate step for recovering …

Canmol : Expert System In Medicine, Kulin Hemani

Theses

The intriguing words for the nineteen nineties are "Expert Systems", and "Artificial Intelligence". To a layman these terms conjure up thoughts of spaceships and futuristic beings. In reality they exemplify man's capability to harness technology.

Expert systems are computer software programs that make use of previously accumulated knowledge to assist in solving complex problems.

In recent years the practice of medicine has changed dramatically from a fundamentally individually deductive approach to an Artificial Intelligence based science. The modern physician no longer draws conclusions simply by examining the patient. Today the physician employs sophisticated computer based diagnostic tools to generate a …

Delay Performance Of Cebus And Modified Cebus Schemes, Altaf Hussain

Theses

In this thesis the performance of the CEBUS (Consumer Electronics Bus), a local area network proposed by the Electronics Industries Association for the 'Smart House,' is analyzed under varying network load and traffic patterns that would occur in a typical home environment. Reduced complexity versions of the CEBUS scheme are compared with the standard CEBUS scheme.

It was found from simulation analysis that the delay in the CEBUS network, at a given network bandwidth, is dependent upon the message priority and the traffic pattern in the network. It was also observed that the performance of a modified CEBUS scheme was …

Radiation From The Cylindrical Dielectric Taper, Tor-Odd Hoydal

Theses

The radiation problem of the cylindrical dielectric taper, excited by the HE₁₁ dominant mode, is studied. A theoretical model and a numerical investigation into the radiation characteristics of such a tapered structure are presented. The model is based upon the combination of the exact modal field solutions for a step profile cylindrical dielectric waveguide, Local Mode Theory, and the Equivalence Principle for the determination of equivalent current densities.

The far-zone radiation field is considered to be the summation of the fields produced by two radiative components in the dielectric rod/conical structure: The "aperture" of the uniform dielectric rod at …

Knowledge Based Designing Of Broadband Coaxial Cable Networks, Tauqir Hameed

Theses

The objective of this research was to build a broadband coaxial cable network. One of the basic requirement of a network is the physical link transmission medium. For the purposes of this research, broadband coaxial cable was chosen as a physical medium of data communication. The approach taken in this research was to divide network design into three main steps. In the first step, the decision on topology of the network was determined. Both Star and Minimum Spanning Tree topologies were used and then the Esau-Williams Algorithm was employed to minimize the cable length. In the second step, various signal …

Gaseous Component Identification With Polymeric Film Sensor, Edward S. Kolesar Jr.

AFIT Patents

A sensor having an interdigitated gate electrode field effect transistor (IGEFET) coupled to an electron beam evaporated copper phthalocyanine thin film is used to selectively detect parts-per-billion concentration levels of atmosphere contaminants such as nitrogen dioxide (NO₂) and diisopropyl methylphosphonate (DIMP). The sensor is excited with a voltage pulse, and its time- and frequency-domain response are examined. The envelopes of the magnitude of the normalized difference frequency spectrums reveal features which unambiguously distinguish the NO₂ and DIMP exposures.

Performance Of The Extended Token Bus Network With Asymmetric Load Distribution, Hong Lin

Theses

The Token Bus, IEEE 802.4, provides high priority message options. The delay of high priority messages becomes an important criterion in the design and management of computer communication networks. A goal of the protocol is to allocate sufficient bandwidth and frequency of access to minimize of the high priority message delay. In this study, a simulation model of a priority based network, consisting of two token bus networks interconnected by a bridge is implemented. The load distribution among stations is asymmetric and the messages are divided into two priorities, high and low. Both fixed and variable token token holding times …

The Performance Evaluation Of A New Neural Network Based Traffic Management Scheme For A Satellite Communication Network, Dequan Liu

Theses

The thesis describes a new neural network based traffic management scheme for a satellite communication network. The scheme consists of two levels of management. The front end of the scheme is a derivation of the Kohonen's self-organization model to configure maps for the satellite communication network dynamically, The model consists of three stages. The first stage is the pattern recognition task which selects an exemplar map that best meets the current network requirements. The second stage analyzes the discrepancy between the chosen exemplar map and the state of the network, and adaptively modifying the chosen exemplar map to conform closely …

Electrical Characterization Of Preoxide Growth Fluorine Incorporated Thin Sio2 Films, Nilay J. Patel

Theses

Analyses of electrical characterization, of thin SiO₂ films grown on virgin and etched silicon surfaces, are presented here. The characterization techniques employed in these experiments are High Frequency Capacitance-Voltage (C-V), Capacitance-Time (C-T) & MOS Doping Profile and Static & Dynamic Current-Voltage (I-V) measurements. The structures, with areas ranging from 0.001-0.05 cm², used in this study are Al/Poly/SiO₂/Si/Al capacitors fabricated on virgin and C₂F₆ CHF₃ + He plasma exposed n-Si substrates. In this experiment, we have studied the effect of sacrificial oxidation. In this step, the oxide is thermally grown on the …

A Microengineered Beam Diaphragm Structure For The High Performance Pressure Sensor, Alkesh Shah

Theses

The thesis details the design for a novel microengineered beam diaphragm structure for piezoresistive pressure sensor applications. The beam diaphragm structure is used as a pressure sensing device, within a Wheatstone bridge circuit. The single crystal silicon with [100] orientation is used for the beam diaphragm structure.

It has the advantages of high sensitivity(2.56 v/v/mm of Hg), good linearity(3Kpa to 1.4 Mpa) and overpressure protection with the help of the bosses. It's protection range is about 400 times the standard pressure range. The beam diaphragm structure has two rectangular bosses which are formed by anisotropic etching. Two pairs of diffused …

Efficient Multiprocessor Scheduling Based On Genetic Algorithms, Hong Ren

Theses

The problem of multiprocessor scheduling can be stated as finding a schedule for a general task graph to be executed on a multiprocessor system so that the schedule length can be minimized. This scheduling problem in known to be NP-hard and methods based on heuristic search have been proposed to obtain optimal and sub-optimal solutions to the problem. Genetic algorithms have recently received much attention as robust stochastic searching algorithms for various optimization problems. In this thesis, we propose an efficient method based on genetic algorithms to solve the multiprocessor scheduling problem. The representation of the search node will be …

Studies Of Electrical Properties Of Sio2 /Inp System, Milind S. Patel

Theses

Analyses of Electrical characteristics, of TilAu/SiO₂1InP structures, are presented here. The (MIS) Metal-Insulator- Semiconductor capacitors were fabricated with oxide thickness of 195nm, 420nm and 610nm respectively. The SiO₂ films were deposited on n-type Indium Phosphide(/nP) using Rapid Thermal Chemical Vapor Deposition (RTCVD). The characterization techniques employed in these experiments were (I-V) Current Voltage and High Frequency Capacitance Voltage (C-V) techniques. The electrical parameters obtained from the I-V and C-V measurements have been discussed here.

Mapping Hierarchical Structures Onto Hypercubes, Sandip C. Patel

Theses

Hierarchically structured arrays of processors are appropriate for low-level and intermediate-level image processing and computer vision. The most widely used structure is the pyramid. Neverthless, pyramid machines do not support the efficient implementation of the majority of scientific algorithms and their cost may become prohibitively high. In contrast, hypercube machines efficiently implement a wide variety of important algorithms due to the versatility of the underlying network. In fact, hypercube-based systems have become commercially available. The hypercube network supports both regular and irregular communications and it can efficiently simulate a variety of other structures like rings, trees, meshes, pyramids, etc. Thus, …

Transmission Ellipsometry On Transparent Unbacked Or Embedded Thin Films With Application To Soap Films In Air, R. M.A. Azzam

Electrical Engineering Faculty Publications

The ratio ρ_t = T_p/T_s of the complex amplitude transmission coefficients for the p and s polarizations of a transparent unbacked or embedded thin film is examined as a function of the film thickness-to-wavelength ratio d/λ and the angle of incidence Φ for a given film refractive index N. The maximum value of the differential transmission phase shift (or retardance), Δ_t = argρ_t, is determined, for given N and Φ, by a simple geometrical construction that involves the iso-Φ circle locus of ρ_t in the complex plane. The …

The Theory Of Bootstrapped Algorithms And Their Applications To Cross Polarization Interference Cancelation, Abdulkadir Dinc

Dissertations

Dual-polarized transmission has become an important method for frequency re-use, particularly in satellite and microwave radio communication. Nevertheless, cross-polarization interference, which is inherent to this method, may cause degradation in system performance.

Different canceler [sic] structures have been proposed to mitigate the effect of cross-polarization. Among these are the diagonalizer, the least mean square (LMS) canceler [sic] and the bootstrapped cancelers [sic]. Bootstrapped canceler [sic] schemes have been proposed and implemented in different applications, such as satellites, tactical communications, and quadrature amplitude madulation [sic] (QAM) dual polarized microwave radio. Nevertheless, no attempt was made in the past to quantify the …

Application Of Non-Imaging Optical Inspection To The Detection Of Pinhole Defects In Latex Condoms, Paul Micha Gelencser

Theses

An optical technique was demonstrated for the detection of pinhole defects in latex condoms. To evaluate the optical inspection concept, a prototype inspection apparatus was constructed. In order to maximize contrast between pinhole transmitted signal and optical signal transmitted through the latex condom material, ultraviolet (u.v.) light of wavelength 253nm has been used. This inspection was performed during rotation of the condom, with the light source inside the condom and the photomultiplier photodetector outside. The form on which the condoms were mounted was made of quartz in order to allow the u.v. light to be transmitted through it.

Background signal …

The Neural Network Based Control System For Dynamic Channel Allocation In Pcn Communications, Ching-Yao Huang

Theses

A neural network based control system (NNCS) is adopted in this paper to conduct the channel allocation task in the personal communication networks (PCN). Binary adaptive resonance theory (ART-1) that was modified for pattern matching and provided the corresponding responses is selected as the basic algorithm for the system. Digital portable radio technology can provide reliable access to high quality wireless service for many users. Low power transmission requirement and small cell size configuration that can support more users and diverse services than cellular radio system are the attractive attributes of PCN. Assigning multiple time slots to a user in …

Automatic Infrared And Visual Inspection Of Solder Joints On Pcbs, Jiang Huang

Theses

This thesis reports the research results of automatic inspection of solder joints on printed circuit boards (PCBs). The previous work on this regard has been advanced significantly in the following three aspects. With the application of some microlens and the principle of geometric optics solder joints of real size are inspected in this work instead of larger simulation solder joints in the previous work. A new set of features is formulated and used for infrared inspection. Consequently, better results have been achieved in this work.

Reasonably good results demonstrate the capability of infrared inspection of solder joints on PCBs. Once …

Direct Recovering Of Composite Surface Using Uoff, Zhesheng Huang

Theses

The research work reported in the thesis is motivated by the problem raised in the computer vision area. It utilizes direct method to recover surface structure of objects in 3-D space from a pair of stereo images. The direct method, compared with optical flow-based approach and feature-based approach, is robust and computationally efficient. However it can only recover planar surface structure so far. A new approach to recover structure from a pair of stereo images based on unified optical flow field (UOFF) is developed recently. It can recover curved surface structure.

In this thesis, the problem of recovering surface structure …

A Comparative Study Of Image Coding Techniques : Filter Banks Vs. Discrete Cosine Transform, Hosam Fawzi Mutlag

Theses

Subband coding of still image frames using Binomial PR-QMF has been presented in this thesis. Simulation results have shown that the performance of subband coding using a low complexity coder is practically the same as the performance of the industry standard (8 x 8) DCT based image coder.

A low bit rate adaptive video coding technique is also introduced in this thesis. The redundancy within adjacent video frames is exploited by motion compensated interframe prediction. The Motion Compensated Frame Difference (MCFD) signals are filtered by employing Binomial PR-QMF structure into four subbands. Then, the subbands are quantized using an efficient …

Task Scheduling For Fms Based On Genetic Algorithm, Hung-Yuan Li

Theses

A Flexible Manufacturing System (FMS) consisting of p automated guided vehicles (AGV's), m workstations and n tasks is studied. The main problem investigated in this thesis is to find an optimal or suboptimal task scheduling for p AGV's among m workstations to complete n tasks.

An efficient approach based on genetic algorithms has been designed and implemented to solve the problem of task scheduling for a FMS. Near-optimal, or even optimal, task scheduling is accomplished by genetic algorithms. Simulation results on the algorithm are also discussed.

A Cmos Logic Circuit To Reduce Substrate Current/Hot Carrier Effect, Tejinder K. Jaswal

Theses

A new C-MOS NAND and CMOS full adder logic circuits which reduces hot carrier problems are discussed. The application of new circuit lowers the channel electric field in N-MOSFET during switching transient and leads to suppression of the N-MOSFET substrate current. The simulation results shows that about 3.99 and 3.75 times smaller peak substrate current are obtained in C-MOS NAND and adder with new circuit compared to the conventional logic circuits. These logic circuits also gives better noise and shows shorter rise and fall times. The new concept provides highly reliable logic circuits without any change of device structure or …

Synthesis And Characterization Of Boron Nitride Masks For X-Ray Lithography, Venkat Paturi

Theses

Boron nitride thin films were deposited on silicon and fused quartz substrates by low pressure chemical vapor deposition using liquid precursor source consisting of Triethyl amine borane complex over a temperature range of 600-900°C. In the range of 600-800°C, the deposition rate, measured at a constant pressure of 0.35 Torr and flow rate of 30 sccm, was observed to follow an Arrhenius behavior yielding an activation energy of 11 kcal/mol. In the temperature range of 800-900°C, the addition of ammonia to Triethylamineborane complex produced films that are stoichiometric, as estimated by RBS measurements, and hydrogen free as determined by Infrared …

A Mouse-Driven Interface For Androx Ics-400, Chin-Tien Chen

Theses

A mouse-driven interface is extremely useful for software performing image processing tasks. This thesis describes an implementation of a mouse-driven interface for the Androx ICS-400 image processing board. The Androx board is housed in a Sun 4/330 running a UNIX-based operating system. The main goal of this interface is to provide a consistent and friendly user interface for image processing tasks and integrating the Sun window libraries with the Androx libraries. Various image processing tasks, such as gray scale and binary morphological operations, histogram, thresholding, filtering, spot, logical operations, arithmetic operations, zooming, scrolling, rank and image acquisition are implemented in …

The Bandwidth Allocation Of Atm Control By Neural Networks, Jin-Syan Chou

Theses

In this thesis, we develop a neural network method based on Adaptive Resonance Theory to train and control the optimum bandwidth allocation of ATM network. In Broadband Integrated Service Digital Network (BISDN), the Asynchronous Transfer Mode (ATM) is already adopted as the transfer facility by CCITT. ATM is a high-bandwidth, low- delay, fast-packet switching and multiplexing technique. Using ATM technique, we can flexibly rearrange the network and reassign the bandwidth to meet the requirement of all types of services. As an effective optimization method, Genetic Algorithm (GA) is applied to implement the bandwidth allocation of ATM. Then, we use Adaptive …

Modeling Of Vacuum Microelectronic Lateral And Vertical Devices, Qiong Gui

Theses

Vertical and lateral configurations of the vacuum microelectronic device have been modeled using the simulation tools. Both cone and ridge cathode structures are used. Simulation results are compared with experimental data where available. These device structures include cathode, extraction grid, anode, and deflectors. The electric field at the tip of the cathode has been calculated for tip radius as small as 0.1nm. The model used takes into account the effect of potential on all electrodes on the E-field at the cathode tip. Also the effect of cathode geometry on the E-field is detailed.

Static characteristics are based on a new …

Representing Tolerances In A Geometric Modeller, Chih-Tsung Huang

Theses

Current geometric modeller contains dimension information only. This thesis describes how tolerance can be added to a geometric modeller. The modeller is based on a hybrid design of the Constructive Solid Geometry (CSG) scheme and Boundary Representation (B-Rep). Various tolerances based on the ANSI standard are considered.

Brushless Dc Motor Speed Control System With Saturation Nonlinearity, Khawja M. Kamal

Theses

A study of a three-phase, pulse-width modulated, velocity controlled brushless DC motor speed control system is presented. Previous works on brushless DC drive systems could not explain global instability, due to linear approximations. A complete three-phase system model is presented here, along with a simplified single-phase model, which is similar to a conventional DC motor model. The models incorporate saturation nonlinearity. The brushless DC drive system is analyzed and simulated. Special emphasis is laid on the study of the limit-cycle phenomenon, due to saturation nonlinearity. Global instability is accounted for and relevant parameter regions are established for global stability. The …