Engineering Commons^™

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 …

Circuit Implementation Of A High-Speed Continuous-Time Current-Mode Field Programmable Analog Array (Fpaa), Osama K. Shana'a

Dissertations and Theses

The growing interest in programmable analog circuits has led to the development of Field Programmable Analog Arrays (FPAAs). An FPAA consists of: 1) a programmable cell that can be reconfigured to perform several analog functions. 2) an architecture that interconnects a number of copies of the programmable cell.

In this thesis, the full monolithic circuit implementation of the analog part of the programmable cell is presented. Chapter I gives an introduction to the idea of FPAA and introduces the FPAA architecture and the cell block diagram. Chapter II deals with the design and verification of a differential current-mode four-quadrant multiplier. …

Low-Frequency Noise In 4h-Silicon Carbide Junction Field Effect Transistors, J. W. Palmour, M. E. Levinshtein, S. L. Rumyantsev, Grigory Simin

Faculty Publications

Low frequency noise in 4H‐silicon carbide junction field effect transistors (JFETs) has been investigated. JFETs with a buried p ⁺ n junction gate were manufactured by CREE Research Inc. Very low noise level has been observed in the JFETs. At 300 K the value of Hooge constant α is as small as α∼10⁻⁵ and the α value can be decreased by an appropriate annealing to α∼2×10⁻⁶. It has been shown that even these extremely low noise values are determined not by the volume noise sources but by the noise at the SiC–SiO₂ interface.

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 …

A Fuzzy Logic Based Approach To Direct Load Control, K. Bhattacharyya, Mariesa Crow

Electrical and Computer Engineering Faculty Research & Creative Works

Demand side management programs are strategies designed to alter the shape of the load curve. In order to successfully implement such a strategy, customer acceptance of the program is vital. It is thus desirable to design a model for direct load control which may accommodate customer preferences. This paper presents a methodology for optimizing both customer satisfaction and utility unit commitment savings, based on a fuzzy load model for the direct load control of appliances

Dispersion Comparison For Dsi- And Tensor-Based Nonorthogonal Fdtd, Hao Shi, James L. Drewniak

Electrical and Computer Engineering Faculty Research & Creative Works

An explicit formulation of the finite-difference time-domain-discrete surface integral (FDTD-DSI) technique has allowed a rigorous study of numerical dispersion for the method. The study shows that the DSI- and tensor-based FDTD methods do not have the same numerical dispersion relation. It also clarifies the recently reported discrepancies in the dispersion relation between the two approaches. This study also shows that the tensor-based FDTD algorithm exhibits better dispersion properties for a two-dimensional uniformly skewed mesh.

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 …

Dependence Of The Normalized Radar Cross Section Of Water Waves On Bragg Wavelength-Wind Speed Sensitivity, David G. Long, R. Scott Collyer, David V. Arnold

Faculty Publications

Measurements of the normalized radar cross section (O) made by the YSCAT ultrawideband scatterometer during an extended deployment on the Canada Centre for Inland Waters (CCIW) Research Tower located at Lake Ontario are analyzed and compared with anemometer wind measurements to study the sensitivity of O to the wind speed as a function of the Bragg wavelength. This paper concentrates on upwind and downwind azimuth angles in the wind speed range of 4.5-12 m/s. While YSCAT collected measurements of O at a variety of frequencies and incidence angles, this paper focuses on frequencies of 2.0, 3.05, 5.30, 10.02, and 14.0 …

Development And Operation Of Buried Channel Charge Coupled Devices In 6h Silicon Carbide, Scott T. Sheppard, Michael R. Melloch, James A. Cooper Jr.

Department of Electrical and Computer Engineering Technical Reports

Silicon carbide is a wide bandgap semiconductor that is well suited for high power, high temperature electronic devices due to its remarkable electronic and thermal properties. Photosensitive devices in the 6H polytype of Sic have also been demonstrated, showing high sensitivity in ultraviolet wavelengths near 270 nm. Furthermore, the native oxide on Sic is silicon dioxide, meaning that SIC can be thermally oxidized to form a high quality gate dielectric, making metal-oxide-semiconductor (MOS) devices possible. These qualities make silicon carbide ideal for constructing UV sensitive CCD imagers. 'This work investigates the feasibility for developing imagers in Sic through the fabrication …

Applications Of The Normal-Incidence Rotating-Sample Ellipsometer To High- And Low-Spatial-Frequency Gratings, Y. Cui, R. M.A. Azzam

Electrical Engineering Faculty Publications

The normal-incidence rotating-sample ellipsometer is an instrument that can be used to characterize grating surfaces from the measured ratio ρof complex reflection coefficients r_y/r_x of light polarized perpendicular and parallel to the grating groove direction. Experimental results at different wavelengths for different gratings with spatial frequencies from 150 to 5880 grooves/mm are presented. The groove depth of the 5880-grooves/mm gold-coated grating can be estimated from the measured ρ and rigorous grating theory.

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 …

Layout Synthesis For Datapath Designs, Naveen Buddi

Dissertations and Theses

As datapath chips such as microprocessors and digital signal processors become more complex, efficient CAD tools that preserve the regularity of datapath designs and result in small layout area are required. The standard-cell placement techniques ignore the regularity of datapath designs and hence give inefficient layouts. This has necessitated the development of new techniques for datapath module placement.

We developed a layout synthesis tool DataPathLAYOUT, for the bit-slice datapath logic designed using standard-cell libraries. We developed fast and area efficient heuristics for placing the cells in a bit-slice such that the regularity of datapath circuits is preserved and the number …

Software Design Control Of An Autonomous Vehicle, Monish Sharma

Honors Capstone Projects and Theses

No abstract provided.

In Situ And Ex Situ Optical Characterization Of Electro Deposited Magneto-Optic Materials, James N. Hilfiker, Darin W. Glenn, Scott W. Heckens, John A. Woollam, Kurt W. Weirman

Department of Electrical and Computer Engineering: Faculty Publications

Electrodeposition is being investigated as a novel and low-cost method to prepare magneto-optic thin film and nanostructured materials. This deposition method allows precise control over thin-film properties and permits deposition of novel magnetic geometries. Multilayers and alloys can be deposited and controlled by adjusting deposition potentials and ion concentrations in the bath. Nickel/cobalt alloys have been electrodeposited from sulfamate, sulfate, and chloride solutions onto Au substrates. The optical properties were monitored in situ with a real-time spectroscopic ellipsometer measuring simultaneously at 44 wavelengths in the 410–750 nm spectral range. In situ measurements have the advantage of determining the material microstructural …

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 …

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. …

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 …

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 …

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.

The Analysis, Simulation, And Implementation Of Control Strategies For A Pulsewidth Modulated Induction Motor Drive, Scott D. Roller, Chee Mun Ong

Department of Electrical and Computer Engineering Technical Reports

The purpose of this research is to analyze, simulate, and compare two different control strategies for a variable speed pulsewidth modulated induction motor drive, and implement one of the control strategies using the Motorola MC68F333 inicrocontroller. The two strategies examined in this technical report are volts per hertz control and field oriented control. The benefits and limitations of each strategy are examined through theoretical analysis. Verification of the analysis is performed by simulating thc strategies usmg the Simulink toolbox of Matlab. The Motorola microcontroller is then used to generate both edge-aligned and center-aligned pulsewidth modulated drive signals for a three …

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 …

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 …

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 …