Digital Commons Network^™

Comparison Of A Distributed Kalman Filter Versus A Centralized Kalman Filter With Fault Detection Considerations, Paul J. Lawrence Jr.

Theses and Dissertations

This project examined the results obtained by simulating an aircraft navigation system with a partial complement of a typical avionics sensor array. Two different techniques of estimation processes were utilized and compared: the conventional Kalman and the federated filter architectures. Areas of interest include error state estimation accuracy and overall performance, residual behavior under normal and induced sensor failure conditions, and potential for failure detection and isolation. Several simulations were accomplished for each filter design and the results were compared in order to verify the validity of the newly developed federated filter architecture. Comparison of the error state estimation accuracies …

Light Injection From An Active Cladding To The Core Of A Fiber Optic Fluorosensor, Alvin Leon Bryant

Electrical & Computer Engineering Theses & Dissertations

A fluorosensor works on the basis of light injection from the clad into the core of an optical fiber. The sensitivity of such a sensor depends on the efficiency of light injection. Conditions necessary for a high injection efficiency are experimentally determined. The refractive index difference between the core and the clad,ⁿcore ^-nclad, must be maximized to achieve a high injection efficiency. Since an air clad has the least refractive index, a bare core fiber will have a maximum efficiency. Standard optical fibers used for communication employ a minimum value for ⁿcore ^-nclad, in order …

Study Of Single-Fiber Fiber Optic Lever Microphone, Trung Duc Nguyen

Electrical & Computer Engineering Theses & Dissertations

Fiber optic sensors are widely used in today's technological applications, providing many advantages that conventional sensors lack. In particular, there is a demand in hypersonic applications to develop microphones to measure acoustic pressure that performs in high temperature and noisy surroundings. This thesis analyzes fiber optic lever microphones (FOLM), since they perform at high temperatures. An FOLM system is an intensity modulated sensor, which is simple to implement and is small in size. Two models of the FOLM have been fabricated and calibrated. The first model uses a seven-element fiber array while the second uses a single-fiber to transmit and …

Absorption Imaging Studies On Intrinsic Gaas, John Samuel Kenney

Electrical & Computer Engineering Theses & Dissertations

A diagnostic technique has been developed which allows recording of the temporal and spatial development of electric field structures in GaAs photoconductive switches. The optical method is based on the Franz-Keldysh effect. Measurements were performed with a Nd:YAG activation laser and a GaAs laser diode as the probe laser. At low applied voltages a 100 atm wide region of high electric field is seen at the cathode only. With increasing voltage strong domain like structures emerge at the anode also. A calibration measurement shows that the electric fields in these domains are well above 50 kV/cm. At a threshold voltage, …

Antecedents, Moderators And Outcomes Of Organizational Commitment, Beatus Kundi

Tanzania Journal of Engineering and Technology (TJET)

This study examined: (I) the impact of the BtruCturaI of tenure, job integration and organizational support on organizational (2) the mediating roles of the cultural values for performance and collectivity, and the intra—individual factorg of organizational identification and the norm of reciprocity Ln the relationahip between the structural factore and organization coamitment; and, (3) the relationghip between organizational cormitment and the ouecome variablen Of abøeneeeigm, turnover and The Bhow that job and Of the for performance a gignificant facilitator of the effecte Of the etructuraL factors on commitment; and organization identification and the norm of rec are important linkø in …

Reduced Bandwidth For Remote Vehicle Operations, Timothy E. Noell, Fred W. Depiero

Electrical Engineering

Oak Ridge National Laboratory staff have developed a video compression system for low-bandwidth remote operations. The objective is to provide real-time video at data rates comparable to available tactical radio links, typically 16 to 64 thousand bits per second (kbps), while maintaining sufficient quality to achieve mission objectives. The system supports both continuous lossy transmission of black and white (gray scale) video for remote driving and progressive lossless transmission of black and white images for remote automatic target acquisition. The average data rate of the resulting bit stream is 64 kbps. This system has been demonstrated to provide video of …

Scattering Of A Light Beam From Waves At An Air-Sea Interface, Donald D. Duncan, W. H. Carter

Electrical and Computer Engineering Faculty Publications and Presentations

The authors report a new theory that describes the scattering of an upward propagating laser beam from the sea through the air-sea interface in the presence of sea waves. The sea is assumed to be a uniform dielectric and conventional scattering theory is employed by using a modification to the first Born approximation that permits treatment of surface refraction phenomena. Methods of statistical radiometry are also used in a new manner by assuming that the surface scattering function for the sea waves can be treated by a quasi-homogeneous source model to calculate the second-order correlation functions for the partially coherent …

Photopolarimeter Based On Planar Grating Diffraction, R. M.A. Azzam, K. A. Giardina

Electrical Engineering Faculty Publications

A division-of-amplitude photopolarimeter (DOAP) is described that employs a diffraction grating in the conventional spectrometer orientation with the grating grooves normal to the plane of incidence. Four coplanar diffracted orders are used for polarimetric analysis to determine all four Stokes parameters of incident light simultaneously and virtually instantaneously (with the speed being determined solely by the photodetectors and their associated electronics); a fifth order is used for alignment by autocollimation or by use of a position-sensing quadrant detector. To sensitize the instrument for the +45° and -45° azimuths of incident linearly polarized light and for the handedness of incident circular …

Phased Array Antenna Analysis Using Hybrid Finite Element Methods, Daniel T. Mcgrath

Theses and Dissertations

This research in computational electromagnetics developed a new method for predicting the near-field mutual coupling effects in phased array antennas, using the finite element method (FEM) in combination with integral equations. Accurate feed modeling is accomplished by enforcing continuity between the FEM solution and an arbitrary number of wave guide models across a ground plane aperture. A periodic integral equation is imposed above the antenna's physical structure in order to enforce the radiation condition and to confine the analysis to an array unit cell. The electric field is expanded in terms of vector finite elements, and Galerkin's method is used …

Minimum Redundancy Array Structure For Interference Cancellation, Wan-Ling Chen

Dissertations

Adaptive antenna arrays are widely used in many advanced radar, sonar, and communication systems because of their effectiveness in cancelling intentional or unintentional interferers. A uniformly spaced linear array, referred to as a Uniform Regular Array (URA), is the usual structure used for interference cancellation. The Minimum Redundancy Array (MRA) structure proposed in this work is a special kind of thinned array whose application was limited in the past to direction finding. MRAs with the same number of array elements can resolve directions of much more closely spaced signals than URAs.

The URA structure is customarily utilized for interference cancellation, …

Adaptive Two-Stage Detection Scheme In Synchronous Two-User Cdma Systems, Yong Jiang

Theses

A conventional single user detector is not optimum in the multiuser environment because the multiuser interference can not be modeled as an additive Gaussian process. Such a receiver is very vulnerable to the near far situation. The receiver that is optimum for multiuser environment has high complexity and requires a knowledge of the received signal energies. Various versions of the receiver that handle the near far situation have been proposed in the literature. In this work, an adaptive two stage scheme for a synchronous two user environment with unknown received energies is proposed. It consists of a, tandem of the …

Modeling And Simulation Of Magnetic Micromotor Performance, Ping Wang

Theses

The objective of this research was to model the performance and optimize geometries for two types of magnetic micromotors: yoke-type (YTMM) and yokeless (YSMM). The two selected micromotor types matched the designs that have been described in the recent research literature. Modeling was accomplished using MAXWELL, an advanced 2-D and 3-D simulator. The micromotors with nickel and nickel-iron magnetic thin films for the rotor and stator were simulated for torque performance. Three-phase power supplies with overlapping and non-overlapping phases were used. Rotor diameter dimensions were varied from 285 to 600µm, and the rotor-stator air gap was varied from 3 to …

Improving The Jitter Performance Of Timing Recovery By Employing Delay Shifts, Xin De Lu

Theses

Many methods have been developed for evaluating the jitter performance of timing recovery circuits for binary synchronous transmission systems. These circuits consist of a nonlinear device followed by a narrowband filter tuned to the pulse repetition frequency. This thesis introduce delay shifts in the timing recovery circuits to improve the jitter performance. The function of the delay shifts is analyzed and mathematical proof of jitter performance improvement is given for the system using square-law device. Finally, the numerical results obtained from the specific examples serve to illustrate the significant improvement between the system with and without delay shifts. That is, …

Polarimetric Fiber Optic Sensor For The Measurement Of Strain, Wei Ma

Theses

In this thesis, development of a Polarimetric Fiber-Optic strain sensor is presented. The sensor uses the phenomenon that strain can deform the probing part of the fiber and hence change the polarization of the transmitted light signal. By counting the resulting fringes, we can measure the exact strain in the material. Calibration of the sensor was achieved by setting up tension tests. Optical fibers were glued on the surface of the specimen. Reference strain gages were used to record the strain in the specimens. Resulting fringes from the fiber optic sensors were then related to the strain measured by the …

The Postbus Fault Tolerant Clos Network, Udayabhanu Sarangapani

Theses

The trend in modern computing is to develop multiprocessor systems with hundreds, even thousands, of processors and memory modules. The task of providing communication paths among all these units is not a trivial one. For a small number of functional units, direct connections could be used but for large systems interconnection networks have to be used. Multistage Interconnection Networks (MINs), provide a dynamic means for interconnecting processors and memory in a multiprocessor system. These networks are built with switches in each stage.

The Clos network is a well defined family of MINs and consists of three stages. The ordinary Clos …

Fair And Efficient Transmission Over Gbps Dual Ring Networks, Abdelnaser M. Adas

Theses

The advances in fiber optics technology provide large bandwidth and enable the support of a wide variety of services. New network architectures have been proposed, such as Metaring and Distributed Queue Dual Bus (DQDB), that try to take advantage of the new capabilities. Because of the very small packet transmission time relative to the feedback time a challenging issue in high speed networks is the efficient and fair share of the channel bandwidth among the competing users. In this thesis we first investigate and compare the performance of the Global and Local Fairness Mechanisms (GFM and LFM, respectively). They have …

Performance Of Different Strategies For Error Detection And Correction In Arithmetic Encoding, George F. Elmasry

Theses

Lossless source encoding is occasionally used in some data compression applications. One of these encoding schemes is the arithmetic encoding.

When data is to be transmitted via communication channel, noise and impurities imposed by the channel cause errors. To reduce the effect of errors, channel encoder is added prior to transmission through the channel. Channel encoder inserts some bits that help channel decoder at the receiver end to detect and correct errors. These added error detection and correction bits are redundancy that causes reduction in the compression ratio and hence an increase in data rate through the channel. The higher …

Multilevel Embeddings For Massively-Parallel Hypercubes, Devenkuma P. Shah

Theses

Hierarchically structured arrays of processors have widely been used in the low and intermediate phases of image processing and computer vision. Since the pyramid structure efficiently supports local and global operations extensively required by these phases, it has been widely used for relevant algorithms. Multilevel systems keep all the advantages of the pyramid structure while providing a general hierarchical structure that is easier to be used for the development of several algorithms and may also provide higher performance.

Although the cost of pyramid machines may be tremendously high, they have limited applications. In contrast, the hypercube network is widely used …

Design Of A 320x122 Mwir-Ccd Ptsi-Si Imaging Radiometer With Automatic Optical Integration Time Control, Nathaniel Joseph Mccaffrey

Theses

An infrared CCD camera system was designed and developed to operate a 320X244 Schottky-barrier IR-CCD Focal Plane Array (FPA) as an imaging radiometer. The goal of this research was to develop a reliable radiometer capable of resolving temperatures between 50 and 1000°C to within 1°C accuracy using non-contact spectral thermographic methods. To accomodate this wide dynamic range, the imager was operated in a non-interlaced format with variable optical integration times ranging from 120µsec to 122msec. Variable integration control was achieved by employing a "dump and read" timing procedure. To facilitate this operation, novel circuitry was developed for dynamically controlling the …

Modeling And Analysis Of Semiconductor Manufacturing Processes Using Petri Nets, Xinyao Wang

Theses

This thesis addresses the issues in modeling and analysis of multichip module (MCM) manufacturing processes using Petri nets. Building such graphical and mathematical models is a crucial step to understand MCM technologies and to enhance their application scope.

In this thesis, the application of Petri nets is presented with top-down and bottom-up approaches. The theory of Petri nets is summarized with its basic notations and properties at first. After that, the capability of calculating and analyzing Petri nets with deterministic timing information is extended to meet the requirements of the MCM models. Then, using top-down refining and system decomposition, MCM …

Effects Of Crosstalk On Fidelity In Page-Oriented Volume Holographic Optical Data Storage, Gregory P. Nordin, P. Asthana

Faculty Publications

Using numerical simulation, we quantitatively examine the effects of cross talk on the recall fidelity of stored binary data in a page-oriented volume holographic memory system. We discuss the trade-off between the signal-to-noise ratio of the reconstructed bits and the optical throughput of the system (i.e., the fraction of the incident beam that is diffracted to the detector plane). We show that significant gains in the signal-to-noise ratio can be achieved with modest decreases in optical throughput in the region where the highest throughput occurs. The magnitude of this trade-off is influenced by both beam degeneracy and coherent recording cross …

Introduction To Electrical Engineering And The Art Of Problem Solving: Volume Ii, P. Frazer Williams

P. F. (Paul Frazer) Williams Publications

These notes were written to accompany a two-semester introductory course in Electrical Engineering. The primary goal of the course is to introduce you to the art of technical problem solving. Conventional Electrical Engineering curricula, in favorable cases at least, produce engineers who are reasonably adept at operating many of the tools important to the field, such as mathematics and circuit analysis. Often, however, these engineers lack skill in choosing which tools to use and in designing a plan of attack to solve problems which are new to them, even though they have all the information and skills needed to fabricate …

Robot Force Velocity Control Using Expert System For Control Mode Changes, William R. Doggett

Electrical & Computer Engineering Theses & Dissertations

The most important property of an automated mechanical system is reliable execution of a specified task. Automated mechanical systems work best in precisely structured environments where all operations are repeatable. Typically, these systems are difficult to modify and expensive to install. Sensors can be used to detect disturbances, thus reducing hardware cost by offsetting the need for precise rigid construction components. Sensors, however, increase the complexity and cost of the control software. Efficient methods of reacting to sensor information during automated system operation are required to reduce software complexity and expense.

This thesis analyzes a robotic construction task and describes …

A Performance Prediction Model For A Fault-Tolerant Computer During Recovery And Restoration, Rodrigo A. Obando

Electrical & Computer Engineering Theses & Dissertations

The modeling and design of a fault-tolerant multiprocessor system is addressed in this dissertation. In particular, the behavior of the system during recovery and restoration after a fault has occurred is investigated. Given that a multicomputer system is designed using the Algorithm to Architecture To Mapping Model (ATAMM) model, and that a fault (death of a computing resource) occurs during its normal steady-state operation, a model is presented as a viable research tool for predicting the performance bounds of the system during its recovery and restoration phases. Furthermore, the bounds of the performance behavior of the system during this transient …

Monolithic Silicon Opto-Electro-Mechanical Light Modulator, Ching-Horng Wu

Theses

A Fabry-Perot light beam modulator of the reflection-type has been designed with process and performance parameters optimized. This design takes advantage of the economies of surface micromaching using silicon substrates and selected thin films. High performance with a low drive voltage are achieved using electrostatic actuation of a thin polysilicon diaphragm. The diaphragm is a novel corrugated structure which has maximum compliance and maintains planarity during actuation. In addition, the corrugationsuspension used provides an improved linearity of amplitude modulation response as a function of the actuation voltage.

A preliminary version of this device has been fabricated through a contract foundry …

Frequency Domain Speech Compression Using The Karhunen-Loeve Transform, Donald W. Dryley

Theses and Dissertations

The purpose of this study was test the influence of phase on the quality of speech reproduced by a speaker dependent compression system. The tests consisted of compressing frequency domain speech vectors using the Karhunen-Loeve Transform, with and without phase, then making subjective judgements as to the reproduced quality. Error Metrics were then tested for their suitability as predictors of reproduced quality. The compression software transformed each speech vector into a vector of complex Fourier coefficients (only half of the coefficients are needed as transform is hermitian). Phase was preserved by using the real frequency components to form one vector …

Smart Memory: An Inexact Content-Addressable Memory, Jack Lee

Dissertations and Theses

The function of a Content-Addressable Memory (CAM) is to efficiently search the information stored in the memory, by using hardware rather than software with a corresponding improvement in searching speed. This hardware allows a parallel search by matching the data stored in memory to a search key rather than sequentially searching address by address as is done in a Random Access Memory. Although existing CAMs are more efficient in finding relevant information than RAM, there are additional improvements that can be made to further improve its efficiency. For example, previous CAMs use a word parallel searching scheme that can only …

Investigation Of The Consumer Electronics Bus, Jaesoo Yang

Dissertations

The objectives of this dissertation are to investigate the performance of the Consumer Electronics Bus (CEBus) and to develop a theoretical formulation of the Carrier Sense Multiple Access with Contention Detection and Contention Resolution (CSMA/CDCR) with three priority classes protocol utilized by the CEBus

A new priority channel assigned multiple access with embedded priority resolution (PAMA/PR) theoretical model is formulated. It incorporates the main features of the CEBus with three priority classes. The analytical results for throughput and delay obtained by this formulation were compared to simulation experiments. A close agreement has been found thus validated both theory and simulation …

On Adaptive Censored Cfar Detection, Loizos Anastasiou Prastitis

Dissertations

In an automatic radar detection system the received signal in every range resolution cell is compared with a threshold to test for the presence of a target. A Neyman-Pearson type test is used which maximizes the probability of detection for a fixed probability of false alarm. For the simple case where the noise is homogeneous a fixed threshold is chosen to achieve the designed constant false alarm rate (CFAR). In the more realistic case the noise background is non-stationary due to clutter and interference. In this situation, the threshold used for testing a particular cell is usually set adaptively using …

Timed Petri Net Simulation Of Flexible Manufacturing Systems, Yan Chen

Theses

Standard Petri nets have been used to model and analyze Flexible Manufacturing Systems. The timed Petri net, which can incorporate the time delay associated with manufacturing events, provides additional information about real time behavior of practical systems. The Timed Petri Net Simulation Tool, a highly interactive graphical tool, is applied to simulate the modeled flexible manufacturing systems. Timed Petri net models are experimented with. Machine utilization data and throughput are obtained. Analysis of the results shows that the system performance can be optimized by choosing proper parameters.