Digital Commons Network^™

Graph Matching Using A Direct Classification Of Node Attendance, Fred Depiero, Mohan Trivedi, Steve Serbin

Electrical Engineering

An algorithm has been developed that finds isomorphisms between both graphs and subgraphs. The development is introduced in the object recognition problem domain. The method isolates matching subgraphs, finds a node-to-node mapping and reorders nodes, thus permitting a direct comparison to be made between the resultant graphs. The algorithm is of polynomial order. It yields approximate results, maintaining a performance level for subgraph isomorphisms at or above 95% under a wide variety of conditions and with varying levels of noise. The performance on the full size comparisons associated with graph isomorphisms has been found to be 100/100, also under a …

Investigation Of Radio Wave Propagation In The Martian Ionosphere Utilizing Hf Sounding Techniques, Robert J. Yowell

Theses and Dissertations

This thesis presents a preliminary design of an ionospheric sounder to be carried aboard one or more of NASA's Mars Surveyor landers. Past Russian and American probes have indicated the existence of an ionosphere, but none of these missions remotely sensed this atmospheric layer from the surface. The rationale for utilizing a surface-based Martian ionospheric sounder is discussed. Based on NASA's choice of launch vehicle and power source, a low-weight, low-powered Chirp sounder using a horizontally-polarized dipole antenna is recommended for the sounder experiment. The sounder experiment should be conducted for at least one Martian year, in order to investigate …

Characterization And Fabrication Of A (6h)-Sic As A Piezoresistive Pressure Sensor For High Temperature Applications, Robert Sylvester Okojie

Dissertations

A prototype monolithic 6H-SiC pressure sensor operational up to 350°C, with potential to operate up to 600°C, was batch fabricated and tested. At temperatures higher than 450°C, silicon diaphragms creep under minimal load. To operate beyond 450°C, therefore, the use of 6H-SiC was proposed. However, three key technological issues - fabrication, high temperature metallization, and gage factor characterization - had to be resolved. Since conventional fabrication technology is not applicable to SiC due to its near inert chemistry, photoconductive selectivity techniques to etch the piezoresistors were developed. Techniques to wet etch the cavities in a dark current mode were developed, …

Explicit Congestion Control Algorithms For Available Bit Rate Services In Asynchronous Transfer Mode Networks, Ambalavanar Arulambalam

Dissertations

Congestion control of available bit rate (ABR) services in asynchronous transfer mode (ATM) networks has been the recent focus of the ATM Forum. The focus of this dissertation is to study the impact of queueing disciplines on ABR service congestion control, and to develop an explicit rate control algorithm.

Two queueing disciplines, namely, First-In-First-Out (FIFO) and per-VC (virtual connection) queueing, are examined. Performance in terms of fairness, throughput, cell loss rate, buffer size and network utilization are benchmarked via extensive simulations. Implementation complexity analysis and trade-offs associated with each queueing implementation are addressed. Contrary to the common belief, our investigation …

A Full Wave Method For Rough Surface Scattering Using Fictitious Current Distributions, Anthony A. Triolo

Dissertations

Rough surface scattering is a current topic of interest in many diverse fields. But, despite its importance, the two most widely used solution methods, the Kirchhoff and first order perturbation methods, are valid only for a restricted range of surface types. There is a large range of surface statistics for which neither of these theories is valid. There are purely numerical solutions to the problem, i.e., the integral equation technique and FDTD method, but these methods require a prohibitively large amount of computer time and storage space for use in practical applications. A full wave method has been introduced by …

Simple Fast Vector Quantization Of The Line Spectral Frequencies, Jin Zhou

Theses

Speech coding has been of interest to communication specialists for years. A number of technologies for describing and transmitting the speech spectral envelope have been studied. Among them, the Vector Quantization (VQ) of Line Spectral Frequencies (LSF) is receiving more attention because of its good rate-distortion performance. Typically, about 30 bits are assigned to code 10-dimensional LSF vectors with a resulting spectral distortion of less than ldB. However, 30-bit full-search VQ is totally impractical in terms of both computational complexity and memory space. Various standard suboptimal, low-complexity VQ techniques have been used for coding the LSF's in the literature. The …

A Digital Signal Processor Based Optical Position Sensor And Its Application To Flexible Beam Control, Thomas J. Spirock

Theses

A Digital Signal Processor (DSP) based optical position sensor was developed. The sensor system consists of the following components: 1) analog electronics, 2) the DSP based synchronous demodulation software, 3) PC based interface software which samples and saves the data, and 4) PC based control codes for a flexible beam. experiment.

The ability of the system to determine the distance from the optical sensor to the power modulated light source was assessed by the following tests: 1) a stationary drift test to evaluate the system's noise, 2) a short-range test to determine the resolution of the optical sensor over a …

Remote Measurement Calibration In Power System, Xiaofeng Li

Theses

Power system reliability and economy of operation require accurate measurements of current, voltage, real and reactive powers. These measurements are transmitted to a control center of a power system for monitoring, display, and use in power system real-time analysis. The number of measurements is in thousands. Routinely field technicians must calibrate transducers and/or determine other sources of metering errors. Due to the large number of measurements and the time required to check each individual measurement, field calibration procedures are impractical, expensive, and not timely.

There has been a need for a more efficient approach to measurement calibration and identification of …

Status Of The Research And Development For Fuel Cell Technology Abroad, Naichao Li, Baolian Yi

Journal of Electrochemistry

Status of the research and development for fuel cell technology abroad was overviewed, and at the aim of accelerating the research and development for fuel cell technology in China, the corresponding stategy for our country was recommended.

United States Patent: System And Method For Compensating Polarization-Dependent Sensitivity Of Dispersive Optics In A Rotating Analyzer Ellipsometer System, Steven E. Green, Shakil A. Pittal, Blaine D. Johs, John A. Woollam, David W. Doerr, Reed A. Christenson

Department of Electrical and Computer Engineering: Faculty Publications

An ellipsometer system which includes a pivotal dispersive optics positioned to receive polychromatic light from an analyzer thereof, without further focusing after reflection from a substrate system, is presented. In addition, a rotating compensator, positioned between the analyzer and the dispersive optics, which serves to reduce detector element polarization dependent sensitivity to light entering thereto after it interacts with the dispersive optics, is disclosed. The method of the present invention can include application of mathematical correction factors to, for instance, substrate system characterizing PSI and DELTA values, or Fourier ALPHA and BETA coefficients.

Problems On The Study Of Anodic Films On Pb In Sulfuric Acid Solution (Ⅱ), Houtian Liu, Qunzhou Wang, Yongqin Wan, Weifang Zhou

Journal of Electrochemistry

The conditions for the growth of the different phases in the anodic Pb(Ⅱ) film on Pb in sulfuric acid solution were discussed.

Electrocatalytic Oxidation Of Some C2 Compounds (Alcohols, Aldehydes, And Carboxylic Acids) On A Pt/SbAd Electrod, Hong Li, Lincai Jiang, Xiong Jiang

Journal of Electrochemistry

The electrocatalytic oxidation behavior of some C₂ compounds(alcohols, aldehydes and carboxylic acids) on a Pt/Sb_ad electrode prepared in-situ or ex-situ UPD was investigated using pontential sweep and rotating disc electrode methods. It is confirmed that Pt/Sb_ad electrode show the most electrocatalytical active to the oxidation of aldehyde functional group and only a little activity to the oxidation of hydroxyl group, but no activity for the oxidation of carboxyl group.

The experimental results show that the activity of the Pt/Sb_ad electrode prepared by ex-situ UPD is higher than that prepared by in-situ UPD.

The limitations of the …

Electrocatalytic Reduction Of Nitrite In The Presence Of Complex Of Cobalt(Ⅱ) And 1,10 Phenanthroline, Jian Tong, Xiaojun Dang, Hulin Li

Journal of Electrochemistry

The electrochemistry of cobalt(Ⅱ)-1,10-phenanthroline Co(Phen)₂²⁺ complex and its ability to electrocatalyze the reduction of nitrite were studied, we found that this complex could act as a catalyst in alkaline or neutral solution for nitrite reduction. We have investigated the effect of the complex composition on electrocatalytic ability. The effects of pH value, complex concentration, regeneration and activation of electrocatalyst on the catalytic current have been studied and discussed.

The Reduction Of Oxygen To Hydrogen Peroxide In An Acidic Trickle Bed Cell Using Graphite Chip Cathode, Zhaoe Lu, Guanyong Zhang, Tiangeng Zhong, Guonu Fang

Journal of Electrochemistry

The authors investigated the electrochemical reduction of oxygen to hydrogen peroxide in 0.05 mol/L H₂SO₄ solution by the trickle bed electrode using graphite chip. The bed dimension was 14×5×0.6 cm. The current efficiency and the concentration of H₂O₂ in the catholyte were determined at various current strengths and various rates of adding the electrolyte. The proper current was 0.15 A. i.e. the current density was 2.1 mA/cm² vertical cross section area of the bed. The concentration of H₂O₂ reached 7×10^-3 mol/L with the current efficiency of 0.2. If the …

Genetic Algorithms Vs. Simulated Annealing: A Comparison Of Approaches For Solving The Circuit Partitioning Problem, Theodore W. Manikas, James T. Cain

Computer Science and Engineering Research

An important stage in circuit design is placement, where components are assigned to physical locations on a chip. A popular contemporary approach for placement is the use of simulated annealing. While this approach has been shown to produce good placement solutions, recent work in genetic algorithms has produced promising results. The purpose of this study is to determine which approach will result in better placement solutions.

A simplified model of the placement problem, circuit partitioning, was tested on three circuits with both a genetic algorithm and a simulated annealing algorithm. When compared with simulated annealing, the genetic algorithm was found …

Mathematics: Meeting The Needs Of High Education, Industry, And The Students Of Electronics Engineering Technology At Hawkeye Community College, Stanley J. Niedermann

Graduate Research Papers

This study pertained to a problem faced by officials of Hawkeye Community College (HCC). With the Tech-Prep educational reform now taking place in the United States and with the ever increasing diversity of electronics, those officials had to make a decision about the status of the courses entitled Applied Algebra and Electronics Math, both of which are included in the electronics engineering technology program at HCC.

The purpose of this study was to determine which mathematics courses were most appropriate for electronics technicians now and in the near future. Three research questions required answers: Question 1 -- should Applied Algebra …

A Comparative Analysis Of Viable Solar Thermal Technologies For Solar Field Development And Commercialization, Sean M. Crawford

UNLV Theses, Dissertations, Professional Papers, and Capstones

Diminishing fossil fuels and concerns about the quality of the environment has lead the recent drive to establish a commercialized solar field in Southern Nevada. The competing solar thermal technologies for the Solar Enterprise Zone (SEZ) are Parabolic Dish-Stirling, Central Receiver Power Towers, and Parabolic Trough Systems. It is important to compare the technologies based on the guidelines set by the Corporation for Solar Technology and Renewable Resources. The variables weighted are solar conversion performances, initial capital investment, operation and maintenance costs, water and land use, and electricity production costs. All technologies have been proven to viable power sources and …

Storage And Delivery Constrained Unit Commitment, Y. Al-Kalaani, F. Eugenio Villaseca, F Renovich Jr

Electrical and Computer Engineering Faculty Publications

A general formulation and the development of a dynamic programming algorithm to solve a fuel-constrained unit commitment problem is presented. The system under consideration has oil units with storage constraints, gas units with delivery constraints, and unconstrained coal units. An optimal approach to transfer the fuel delivery constraints into unit capacity limits using a closed-form dual dispatch is introduced. As a result, the gas units can be viewed as fuel-unconstrained, thus greatly reducing complexity. It is shown that the optimization problem, which requires that storage levels be parameterized, leads to two different dispatch rules. The oil units are dispatched to …

United States Patent: System And Method For Compensating Polarization-Dependent Sensitivity Of Dispersive Optics In A Rotating Analyzer Ellipsometer System, Blaine D. Johs, Shakil A. Pittal, Steven E. Green, John A. Woollam, David W. Doerr, Reed A. Christenson

Department of Electrical and Computer Engineering: Faculty Publications

An ellipsometer system which includes a pivotal dispersive optics positioned to receive polychromatic light from an analyzer thereof, without further focusing after reflection from a substrate system, is presented. In addition, a stationary compensator, positioned between an analyzer and the dispersive optics, which serves to reduce detector element polarization dependent sensitivity to light entering thereto after it interacts with the dispersive optics, is disclosed. The use of a light fiber to carry light from a source thereof, to a polarization state generator, is also disclosed. The method of the present invention can include application of mathematical correction factors to, for …

Using An Evolutionary Strategy To Solve Frequency Allocation Problems, Min Chen

Masters Theses

Frequency allocation problem (F AP) is to assign radio frequencies to a number of stations subject to a number of constraints, so that the minimum interference is suffered. FAP is NP-complete. In order to solve FAPs, there are interference constraints to be satisfied. There are two constraints of FAP which were the focus of this study: (1) co-channel interference, (2) adjacent channel interference.

Evolutionary Strategies (ESs) are very efficient optimization algorithms based upon the principles of adaptive selection found in nature. In this study, a (μ,A)ES algorithm was implemented to solve instances of FAP.

This thesis has demonstrated that …

Frequency Response Enhancement Of A Flow Sensor Using Diamond Thin Films Synthesized By Plasma Cvd, John Curren Hagwood

Electrical & Computer Engineering Theses & Dissertations

Theoretical modeling conducted previously in our Microelectronics Laboratory has shown that a layer of diamond film inserted between a metal film and a substrate will enhance the frequency response of a conventional thin film flow sensor. This thesis involved fabricating and testing a conventional thin film sensor of nickel on quartz (Ni/Q) and a diamond enhanced sensor (Ni/D/Q) for comparative frequency response analysis to validate the theory. Diamond films were grown onto quartz substrates using a microwave plasma enhanced chemical vapor deposition process. Conditions were established to synthesize continuous diamond films on quartz substrates. These films were characterized by scanning …

Wavelength Modulation Spectroscopy With Diode Lasers, Ying Lu

Electrical & Computer Engineering Theses & Dissertations

Wavelength Modulation Spectroscopy is a non-intrusive technique which enables several parameters such as concentration, velocity, and temperature of a target specie to be measured. The method involves a modulation of a probe laser beam and detection at the fundamental, or any harmonic frequency, by a phase-sensitive apparatus. The theory of wavelength modulation is discussed. Effects of the finite value of the wavelength modulation index, together with the effects of any residual amplitude modulation that often occurs simultaneously in a diode laser, are included. It is shown that there are several advantages in using detection harmonics orders greater than the second. …

Gamma-Ray Optical Studies Of ⁷³Ge And ⁵⁷Fe, Walter Carlton Mcdermott Iii

Physics Theses & Dissertations

The research described herein is among the first attempts to test one of the more popular theories for development of a gamma-ray laser. This work is a "marriage" between the Borrmann effect, which is a consequence of the dynamical theory of x-ray diffraction, and time-filtering which comes from time-domain Mossbauer spectroscopy.

Our experiments involved the search for a nuclear Borrmann effect and the subsequent time-filtering effect using ⁵⁷Fe and ⁷³Ge. In both cases, no nuclear Borrmann effect was observed; however, the methodology and criteria necessary for such an observation with any isotope were documented. The procedures necessary for …

Adaptive Integration Of Audio And Visual Information Using Discrete And Semi-Continuous Hidden Markov Models In Audiovisual Automatic Speech Recognition, Qin Su

Electrical & Computer Engineering Theses & Dissertations

An audiovisual semi-continuous hidden Markov model (HMM)-based Automatic Speech Recognition (ASR) system and an improved method of integrating audio and visual information in an audiovisual discrete HMM-based ASR system are investigated.

In the audiovisual discrete HMM, an adaptive integration formulation is employed, which incorporates the integration into the HMM at a pre-categorical stage. A visual weighting parameter is determined automatically, which allows the relative contribution of audio and visual information to be adjusted adaptively. Using an adaptive weight, the accuracy increased by 13% compared to the same model with no adaptive weight.

The semi-continuous HMM is a class of models …

Variable Step Size Lms Adaptive Filters With Delayed Coefficient Updating, Guixian Xu

Electrical & Computer Engineering Theses & Dissertations

A new approach to delayed LMS adaptive filtering is presented, which uses a variable step size for coefficient updating to increase convergence speed and improve tracking characteristics. The new algorithm, called delayed variable step size LMS (DVLMS), is explained, analyzed, and simulated to experimentally determine performance characteristics. Three different strategies for adjusting the step size are examined, and their performance is compared. Also, simulation results are presented to show that the proposed DVLMS systems provide faster convergence and lower mis-adjustment than previously proposed DLMS systems.

Speech Feature Computation For Visual Speech Articulation Training, Stefan Auberg

Electrical & Computer Engineering Theses & Dissertations

A new version of the Visual Speech Articulation Training Aid was implemented which provides real-time visual feedback for speech articulation training. This version was migrated to a Windows Multimedia PC from a previous version which used a Personal Computer (PC) system and additional specialized and expensive custom hardware. This new version will make the system more available to schools and private users. A new method was developed for computing spectral/temporal features which characterize the speech sounds. In addition to the typical frame-based spectral analysis parameters, the new method represents temporal changes of the spectrum with a small number of features. …

An Enhanced Signal Processing Strategy For Fetal Heart Rate Detection, Charles Brewton

Electrical & Computer Engineering Theses & Dissertations

The goal of the research was to improve the signal processing strategy for an acoustic fetal heart rate monitor. The theory, implementation, and testing of several possible signal processing strategies for fetal heart rate detection are presented. The enhanced signal processing strategy implemented is discussed and justified with off-line Matlab simulations and real-time experiments. A FIR matched filter was used as a preprocessor to increase the SNR of the acoustic fetal heart signal. The Teager energy operator and autocorrelation, used in the previous version of the monitor, were combined with a matched filter. Linear prediction and quadratic energy detection were …

Electron Beam Emission From A Ferroelectric Cathode, Crystal Briana Garland

Electrical & Computer Engineering Theses & Dissertations

The electron beam emission from a LTZ-2 (lead titanate-zirconate) ferroelectric cathode was characterized. The purpose was to determine the operation range for this type of electron emitter. The experimental apparatus consisted of a high voltage driving circuit with a charging voltage up to 30kV. A solid-state SCR switch is used to generate the high voltage pulse which induces a polarization change. Current densities on the order of 80A/cm² 30kV were achieved. The electron beam profile is Guassian. At long anode-cathode distances the measured current densities were found to be above Child-Langmuir space charge limits. The large current densities and …

Comparison Of Function Approximation With Sigmoid And Radial Basis Function Networks, Gary Russell, Laurene V. Fausett

Electrical Engineering and Computer Science Faculty Publications

Theoretical and computational results have demonstrated that several types of neural networks have the universal approximation property, i.e., the ability to represent any continuous function to an arbitrary degree of accuracy, given enough hidden units. However, practical considerations, such as the relative advantages of different networks for function approximation using a small to moderate number of hidden units, are not as well understood. This paper presents preliminary results of investigations into the comparison of networks using sigmoidal activation functions and networks using radial basis functions. In particular, we consider the ability of several such networks to learn mappings from the …

Similarity-Based Learning For Pattern Classification, Laurene V. Fausett

Electrical Engineering and Computer Science Faculty Publications

Several standard neural networks, including counterpropagation networks, predictive ART networks, and radial basis function networks, are based on a combination of clustering (unsupervised learning) and mapping (supervised learning). A comparison of the characteristics of these networks for pattern classification problems is presented.