Engineering Commons^™

Field Emission And Breakdown Processes In Vacuum Gaps With Sio(X)-Coated Cathodes, Raymond Jack Allen Iii

Electrical & Computer Engineering Theses & Dissertations

Field emission of electrons is the major cause of electrical breakdown in high voltage systems in vacuum. The highest hold-off electric field of the carefully polished and cleaned stainless steel cathodes was increased to 70MV/m. Thin silicon monoxide, SiO_x, cathode coatings reduced field emission and increased the hold-off field further. Coating the stainless steel cathodes with 2μ SiO_x reduced the field emission current by at least two orders of magnitude at field of 50MV/m and increased the breakdown field to 140MV/m, doubling the breakdown voltage.

The increase in hold-off voltage with SiO_x coatings is discussed in …

Building Lms Adaptive Filters With Register-Based Fpgas, Li Ding

Electrical & Computer Engineering Theses & Dissertations

In this thesis, an 8-bit least mean squares (LMS) adaptive digital filter with 16 coefficients is implemented on a single FPGA, using the MaxPlus+2 design environment. The system is constructed as a hierarchical structure, using four different levels of design hierarchy. Subdesigns at each level of the hierarchy project are complied, fitted and simulated to test and verify their functional correctness. The complete system is tested and verified by checking the MaxPlus+2 simulator results against fixed-point integer arithmetic simulations written in Matlab. The resulting adaptive filter is subsequently mapped to the Alters FLEX I OK20TC144-3 device, resulting in a 14,500 …

Material Evaluation By Pulsed Diode Laser Optoacoustics, Xiaodong Xu

Electrical & Computer Engineering Theses & Dissertations

Pulsed diode laser optoacoustic diagnostics were carried out to characterize solid sample materials. The apparatus developed is compact, portable, cost-effective and therefore very promising for both industrial as well as laboratory applications. To our knowledge, this is the first time that optoacoustic characterization and measurement have been performed with a diode laser. The method was successfully applied to measure the thickness of a multilayer structure non-intrusively. Internal cracks of the material were detected by this technique.

A theory for optoacoustic signal generation, propagation and detection is given. A numerical analysis technique is developed to solve for the expected signal. In …

Multiple-Input Joint Transform Correlator For Wavelet Feature Extraction, Samuel Peter Kozaitis, Mark A. Getbehead

Electrical Engineering and Computer Science Faculty Publications

We describe a joint transform correlator (JTC) that uses multiple input images encoded in the spatial domain for multiwavelet feature extraction. We extend the theory of a JTC to multiple inputs, which enables various combinations of cross-correlations between input images to be performed. Furthermore, we provide experimental results for four inputs with an optically addressed spatial light modulator in the Fourier plane. In addition, it is possible that the space-bandwidth product for multiwavelet feature extraction can be made the same as for a two-input JTC. © 1998 Society of Photo-Optical Instrumentation Engineers.

Thermal Lattice Boltzmann Simulations Of Variable Prandtl Number Turbulent Flows, Min Soe, George Vahala, Pavol Pavlo, Linda L. Vahala, Hudong Chen

Electrical & Computer Engineering Faculty Publications

Thermal lattice Boltzmann (TLBE) models that utilize the single relaxation time scalar Bhatnagar, Gross, and Krook collision operator have an invariant Prandtl number. For flows with arbitrary Prandtl number, a matrix collision operator is introduced. The relaxation parameters are generalized so that the transport coefficients become density independent. TLBE simulations are presented for two-dimensional free decaying turbulence induced by a strongly perturbed double velocity shear layer for various Prandtl numbers.

Hermite–Sinusoidal-Gaussian Beams In Complex Optical Systems, Lee W. Casperson, Anthony A. Tovar

Electrical and Computer Engineering Faculty Publications and Presentations

Sinusoidal-Gaussian beams have recently been obtained as exact solutions of the paraxial wave equation for propagation in complex optical systems. Another useful set of beam solutions for Cartesian coordinate systems is based on Hermite–Gaussian functions. A generalization of these solution sets is developed here. The new solutions are referred to as Hermite–sinusoidal-Gaussian beams, because they are in the form of a product of Hermite-polynomial functions of either complex or real argument, sinusoidal functions of complex argument, and Gaussian functions of complex argument. These beams are valid for propagation through systems that can be represented in terms of complex beam matrices, …

Tooth Contact Sensing Apparatus And Method, John D. Summer, Edmund Pierzchala, Marek Perkowski

Electrical and Computer Engineering Faculty Publications and Presentations

An apparatus and method for sensing tooth contact includes at least one, and more typically plural, vibration sensors which are coupled to the non-biting surfaces of teeth. These sensors produce output signals when the associated teeth contact one another during jaw closing, the output signals being processed to provide information concerning tooth contact. For example, information concerning the ?rst tooth which contacts may be determined, the sequence of contact by various teeth may be determined, as well as the time between contact of the various teeth. Other information concerning tooth contact may also be determined and dis played in a …

Ellipsometric Determination Of Optical Constants For Silicon And Thermally Grown Silicon Dioxide Via A Multi-Sample, Multi-Wavelength, Multi-Angle Investigation, C. M. Herzinger, B. Johs, W. A. Mcgahan, John A. Woollam, W. Paulson

Department of Electrical and Computer Engineering: Faculty Publications

Optical constant spectra for silicon and thermally grown silicon dioxide have been simultaneously determined using variable angle of incidence spectroscopic ellipsometry from 0.75 to 6.5 eV. Spectroscopic ellipsometric data sets acquired at multiple angles of incidence from seven samples with oxide thicknesses from 2 to 350 nm were analyzed using a self-contained multi-sample technique to obtain Kramers–Kronig consistent optical constant spectra. The investigation used a systematic approach utilizing optical models of increasing complexity in order to investigate the need for fitting the thermal SiO₂ optical constants and including an interface layer between the silicon and SiO₂ in modeling …

The Rationale For Negligible Risk Exemptions In The Telecommunications Act Of 1996: Cellular Phone And Personal Communication System Transmitters, Gregg H. Claycamp

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

Dr. Claycamp explains the adequacy of current legislation and regulation.

Joint Wavelet Transform Correlation With Separated Target And Reference Planes, Boon Yi Soon, Mohammad A. Karim, Russell C. Hardie, Mohammad S. Alam

Electrical and Computer Engineering Faculty Publications

In recent years, we realize the usefulness of feature extraction for optical correlator and hereby, we investigate the capability of Laplace operator in feature extraction of multiple targets. The first-order terms and the false alarm terms in the correlation output would be removed using electronic power spectrum subtraction technique. Most importantly, the entire magneto-optic SLM is completely utilized for displaying only targets in the input scene. A new cost efficient hardware implementation is proposed and aforementioned result of the proposed system is evaluated through computer simulation.

Spatial Resolution Enhancement Of Ssm/I Data, David G. Long, Douglas L. Daum

Faculty Publications

One of the limitations in using Special Sensor Microwave/Imager (SSM/I) data for land and vegetation studies is the relatively low-spatial resolution. To ameliorate this limitation, resolution-enhancement algorithms can be applied to the data. In this paper, the Backus-Gilbert inversion (BGI) technique and the scatterometer image-reconstruction (SIR) algorithm are investigated as possible methods for creating enhanced resolution images from SSM/I data. The two algorithms are compared via both the simulation and the actual SSM/I data. The algorithms offer similar resolution enhancement, though SIR requires significantly less computation. Sample results over two land regions of South America are presented.

Channel-Mismatch Compensation In Speaker Identification Feature Selection And Adaptation With Artificial Neural Networks, Edmund A. Fitzgerald

Theses and Dissertations

We develop and present results of an artificial neural network (ANN) based compensation technique for mismatched classifier training and testing conditions in speaker identification (SID). One ANN per feature per speaker is trained to perform a mapping of that feature from a corrupted condition to an undistorted condition. Therefore, a classifier trained under one condition may be used to classify data collected under a different condition. Speech utterances from 168 speakers, collected in a studio, and also re-recorded after transmission over telephone networks, are used for developing and testing the method. Peak formant resonant frequencies, their bandwidths, and pitch are …

Real Time Detection Of Anomalous Satellite Behavior Has Ground Based Telescope Images, Geoffrey S. Maron

Theses and Dissertations

Air Force analysts are faced with the task of monitoring satellites with ground based telescopes. Images are collected and analyzed in a time consuming and subjective effort to detect any behavior that is anomalous. This research maximizes use of a priori information to create an automated, real time satellite behavior classification tool. Using modeling software and knowledge of a satellite's orbit, reference imagery is created for each measured image in a satellite pass. Features are extracted from the measured and reference image pairs that provide good overall Gaussian classification accuracy (85%), reduce the dimensionality of the problem (from 32,768 down …

Preliminary Design Of A Joint Simulation, Analysis, And Wargaming Center For The Turkish General Staff, Oguz Okuyucu

Theses and Dissertations

This study develops a framework for the design of a Joint Simulation, Analysis, and Wargaming Center (JSAWC). JSAWC is proposed as the primary decision support center for the Turkish General Staff. The complexity of warfare systems and the fog of future wars make military planning, problem solving, and decision making processes difficult to accomplish without using computerized analysis support tools. The proposed JSAWC will use modeling and simulation technology to provide analytical support for Turkish military decision-makers and planners in operations planning, force structuring, and training. An iterative systems engineering process is defined and applied to the primary design of …

Modified Multiple Model Adaptive Estimation (M3Ae) For Simultaneous Parameter And State Estimation, Mikel M. Miller

Theses and Dissertations

In many estimation problems, it is desired to estimate system states and parameters simultaneously. However, inherent to traditional estimation architectures of the past, the designer has had to make a trade-off decision between designs intended for accurate state estimation versus designs concerned with accurate parameter estimation. This research develops one solution to this trade-off decision by proposing a new architecture based on Kalman filtering (KF) and Multiple Model Adaptive Estimation (MMAE) techniques. This new architecture, the Modified-MMAE (M³AE), exploits the benefits of an MMAE designed for accurate parameter estimation, and yet performs at least as well in state …

Studies Of Metallic Multilayer Structures, Optical Properties, And Oxidation Using In Situ Spectroscopic Ellipsometry, Xiang Gao, Jeff Hale, Scott Heckens, John A. Woollam

Department of Electrical and Computer Engineering: Faculty Publications

In situ spectroscopic ellipsometry (SE) has been successfully used to accurately measure sputter deposition rates and optical constants of un-oxidized metal layers and to control the growth of magnetic multilayers. The structures include [Co/Cu] _n , [Co/Au] _n , [Co/Ni] _n , [Co/Pd] _n and [Co/Pd/ Au] _n . Layer thickness precision is better than ±0.05 nm for layer thicknesses in the range of 0.2 nm to 10 nm. Closed-loop feedback control of layer thickness is also demonstrated. Good consistency was obtained by comparing the in situ SE results to x-ray diffraction measurements. Dynamic oxidation studies of [Co/Au] _n and …

Multiple Model Adaptive Estimation Using Filter Spawning, Kenneth A. Fisher

Theses and Dissertations

Multiple Model Adaptive Estimation with Filter Spawning is used to detect and estimate partial actuator failures on the VISTA F-16. The truth model is a full six-degree-of-freedom simulation provided by Calspan and General Dynamics. The design models are chosen as 13-state linearized models, including first order actuator models. Actuator failures are incorporated into the truth model and design model assuming a "failure to free stream . Filter Spawning is used to include additional filters with partial actuator failure hypotheses into the Multiple Model Adaptive Estimation (MMAE) bank. The spawned filters are based on varying degrees of partial failures (in terms …

A Game-Theoretic Improvement Model For Stochastic Networks: Reliability Vs. Throughput, Jeffrey A. Schavland

Theses and Dissertations

Prescriptive models used to allocate resources for network improvement traditionally have used reliability or flow as Measures of Effectiveness (MOEs). Such metrics do not give value to efforts which make a component more difficult to exploit. This study developed an entirely new MOE for stochastic network improvement, flow damage utility, which uses a two person, zero-sum, non-cooperative game to optimize a probabilistic network for an estimate of expected flow minus performance degradation after a worst case component loss. A multiple criteria optimization problem that uses flow damage utility and an analogous, previously developed metric for the reliability problem is used …

Linear Reconstruction Of Non-Stationary Image Ensembles Incorporating Blur And Noise Models, Stephen D. Ford

Theses and Dissertations

Two new linear reconstruction techniques are developed to improve the resolution of images collected by ground-based telescopes imaging through atmospheric turbulence. The classical approach involves the application of constrained least squares (CLS) to the deconvolution from wavefront sensing (DWFS) technique. The new algorithm incorporates blur and noise models to select the appropriate regularization constant automatically. In all cases examined, the Newton-Raphson minimization converged to a solution in less than 10 iterations. The non-iterative Bayesian approach involves the development of a new vector Wiener filter which is optimal with respect to mean square error (MSE) for a non-stationary object class degraded …

Performance Of Imaging Laser Radar In Rain And Fog, Kathleen M. Campbell

Theses and Dissertations

The Air Force is currently developing imaging laser radar systems (ladar) for use on precision guided munitions and other imaging systems. Scientists at Eglin Air Force Base, in conjunction with Wright Laboratories, are testing a 1.06-um wavelength ladar system and need to understand the weather effects on the ladar images. As the laser beam propagates through the atmosphere, fog droplets and raindrops can cause image degradation, and these image degradations are manifested as either dropouts or false returns. An analysis of the dropouts and false returns helped to quantify the performance of the system in adverse weather conditions. Statistical analysis …

Field Solutions For Bidirectional High-Gain Laser Amplifiers And Oscillators, Lee W. Casperson, Mohammad Azadeh

Electrical and Computer Engineering Faculty Publications and Presentations

General analytical solutions are obtained for the amplitude, phase, and intensity of the electromagnetic waves in bidirectional homogeneously broadened high-gain laser amplifiers and oscillators. These solutions are important as increasingly high-gain lasers are being employed in practical systems. Expressions are derived relating the output power to the input, including the effects of arbitrary mirror reflectivities and frequency detunings from the line center. For negligible reflectivities, these regenerative amplifier results reduce to earlier expressions for single-pass high-gain amplifiers. Multivalued outputs also occur, and in the limit of low gain per pass the results are consistent with earlier studies of single-frequency laser …

Understanding Comics: The Invisible Art, Alan D. Manning

Faculty Publications

INSIGHTS about professional communication may come from odd and unexpected places. McCloud's Understanding Comics (hereafter UC) is a case in point. Despite the juvenile connotations evoked by any discussion of comic books, the theory of visual communication presented in UC arguably rivals the best of contemporary semiotics (that is, the study of how we make meaning out of gestures, words, paragraphs, pictures, and so on).

Studies Of Surface Electrochemistry And Electrocatalysis At Atomic And Molecule Level, Shigang Sun

Journal of Electrochemistry

The main progresses achieved during last few years in our research group concerning studies of surface electrochemistry and electrocatalysis were reviewed in this present paper. Four topics were described: 1) the surface electrochemistry and model electrocatalysis of metal single crystal planes, 2) the electrocatalytic reaction mechanism and the control of reaction pathways at molecule level, 3) the reaction kinetics of electrooxidation of small organic molecules, and 4) the relationship between the properties and the surface chemical states of electrocatalyst. This review lays in emphasis on the demonstration of the results as well as the research direction of surface electrochemistry and …

A Preliminary Study On Thin Film Plasticizing Lithium Ion Battery, Quanfeng Dong, Hanxi Yang, Xinping Ai, Xiaohong Hu, Shengxian Li

Journal of Electrochemistry

A dry polymer electrolyte was made by plasticizing a copolymer matrix and further filling with liquid electrolyte. A thin-film lithium ion battery based on the dry polymer electrolyte was manufactured and its electrochemical properties were measured. It is found that the thin film lithium ion battery exhibits similar discharge properties to liquid electrolyte battery, and shows strong high rate capability.

Study On The Synthesis And Electrochemical Behavior Of Poly (Quinonoid-Disulfide), Xiaohui Tang, Xiuwu Sun, Yongfang Li, Shibi Fang

Journal of Electrochemistry

Organic polydisulfide containing quinonoid structure was synthesized by chloromethylation, oxidation by nitric acid, and condensation polymerization with sodium disulfide. The effect of quinonoid structure on the electrochemical behavior of organic polydisulfide was investigated with cyclic voltammetry and chargedischarge measurement. The result shows that quinonoid struture mainly affects the positions of redox peaks of organic polydisulfide, open circuit voltage and discharge platform voltage of cell with the organic polydisulfide as cathode.

The Investigations Of Surface Treatment Methods And Characterization Of Oxide Films On Ab5 Based Metal Hydride Electrodes Ⅰ. New NiRich Treatment Methods And Photoelectrochemical Characterization Of Oxide Films, Junmin Nan, Yong Yang, Jun Li, Zugeng Lin

Journal of Electrochemistry

Two simple and efficient surface treatment methods for AB₅ type hydrogen storage alloys were developed. The results of X-ray photoelectron spectroscopy (XPS) and cyclic voltammetric (CV) experiments showed that the hydrogen storage alloys treated by two different methods had Ni rich surface layer so that the performances of the electrodes were improved after treatment. The characterization of the oxide films which formed on the surface of electrodes through potentiodynamic oxidation with the help of photoelectrochemical microscopy (PEM) were done. The anodic photocurrent and the cathodic photocurrent related to the oxidation of hydrogen and the reduction of oxygen on the …

A Study On Heterogeneous Indirect Electrosynthesis Of Benzaldehyde, Daobao Chu, Changjian Lin, Huashui Lin, Jianguang Tan

Journal of Electrochemistry

Heterogeneous indirect electrosynthesis process of benzaldehyde has been investigated using cyclic voltammetry and polarization curves. An optimum condition for preparation of benzaldehyde by indirect electrooxidation of toluenc with redox Mn³⁺/Mn²⁺ is given in this paper. Electrolytic regeneration Mn³⁺ are made at Pt/Ti anode in “slurry” MnSO₄/H₂SO₄ medium. Current efficiency for electrolytic regeneration Mn³⁺  was maintained over 88% by “double cyclic way”.

Investigation Of Methanol Anode Electrooxidation Catalysts, Gangyao Wen, Ying Zhang, Zhenglong Yang, Changzhi Li

Journal of Electrochemistry

A series of catalysts, Pt-WO₃/C, Pt/Ru/C and Pt-Ru-WO₃/C were prepared by chemical reduction deposition. Electrocatalytic oxidation of methanolon different catalyst/Nafion membrane electrodes was studies by voltammetry and current-potential polarization. The results indicated that the catalytic activity order of different catalysts is as follows: Pt-Ru-WO₃/C > Pt-Ru/C > Pt-WO₃/C. At the same time, influences of methanol concentrations and catalyst proportion on performances of anodes were also studies.

Progresses In Surface Electrochemistry And Electrocatalysis ——A Review On The 1997 Joint International Meeting Of Electrochemistry And 97' International Meeting Of Surface Electrochemistry, Shigang Sun

Journal of Electrochemistry

The progresses in surface electrochemistry and electrocatalsis reported in the 1997 joint international meeting of electrochemistry and in the 97′ international meeting of surface electrochemistry were reviewed. The main trends described in this paper consisted of 7 aspects: 1) the studies employing single crystal electrodes, 2) the development of in situ methods of diverse spectroscpoy, 3) the innovation of new research techniques, 4) the preparaton of electrocatalyst of high performances, 5) the quantitative studies on kinetics of electrocatalytic reactions, 6) the investigation on the dynamic processes of surface by timeresolved methods, and 7) the theoretical modeling and simulation of surface …

Anchor Effect Of Iron And Cobalt To Platinum On Carbon Substrates, Zidong Wei, Hetong Guo, Zhiyuan Tan

Journal of Electrochemistry

The cathodic reduction of oxygen is studied on porous carbonbased electrodes carrying platinumiron and/or cobalt alloy catalysts. Electrodes using such electrocatalysts, particularly when used as cathodes in acidic electrolytes, remain stable for longer periods. The cathodic polarization of oxygen reduction on such electrodes is 20 mV to 40 mV lower than that on the conventional electrode on which only platinum alone is used as an electrocatalysts. An accelerated aging test (AAT) is used to evaluate the corrosion resistance and sintering resistance of each catalyst. The dissolution of the catalyst in the AAT filtrate is analysed and provides a measure of …