Open Access. Powered by Scholars. Published by Universities.®

Engineering Commons

Open Access. Powered by Scholars. Published by Universities.®

University of Nevada, Las Vegas

Electrical and Computer Engineering

Keyword
Publication Year
Publication
Publication Type

Articles 361 - 374 of 374

Full-Text Articles in Engineering

A Stochastic Model For Crystal-Amorphous Transition In Low Temperature Molecular Beam Epitaxial Si(111), R. Venkatasubramanian, Suresh Gorantla, S. Muthuvenkatraman, Donald L. Dorsey Dec 1996

A Stochastic Model For Crystal-Amorphous Transition In Low Temperature Molecular Beam Epitaxial Si(111), R. Venkatasubramanian, Suresh Gorantla, S. Muthuvenkatraman, Donald L. Dorsey

Electrical & Computer Engineering Faculty Research

Molecular beam epitaxial Si (111) grown below a certain temperature result in amorphous structure due to the limited surface mobility of atoms in finding correct epitaxial sites. In spite of many experimental and theoretical studies, the mechanism of crystal‐amorphous transition and its dynamics related to the growth conditions are not well understood. In this article, we present a theoretical model based on the formation of stacking fault like defects as a precursor to the amorphous transition of the layer. The model is simulated based on a stochastic model approach and the results are compared to that of experiments for temperatures …


A Comparative Analysis Of Viable Solar Thermal Technologies For Solar Field Development And Commercialization, Sean M. Crawford May 1996

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 …


A Self-Consistent Numerical Method For Simulation Of Quantum Transport In High Electron Mobility Transistor; Part 1: The Boltzmann-Poisson-Schrodinger Solver, Rahim Khoie Jan 1996

A Self-Consistent Numerical Method For Simulation Of Quantum Transport In High Electron Mobility Transistor; Part 1: The Boltzmann-Poisson-Schrodinger Solver, Rahim Khoie

Electrical & Computer Engineering Faculty Research

A self-consistent Boltzmann-Poisson-Schrödinger solver for High Electron Mobility Transistor is presented. The quantization of electrons in the quantum well normal to the heterojunction is taken into account by solving the two higher moments of Boltzmann equation along with the Schrödinger and Poisson equations, self-consistently. The Boltzmann transport equation in the form of a current continuity equation and an energy balance equation are solved to obtain the transient and steady-state transport behavior. The numerical instability problems associated with the simulator are presented, and the criteria for smooth convergence of the solutions are discussed. The current-voltage characteristics, transconductance, gate capacitance, and unity-gain …


A Self-Consistent Numerical Method For Simulation Of Quantum Transport In High Electron Mobility Transistor; Part Ii: The Full Quantum Transport, Rahim Khoie Jan 1996

A Self-Consistent Numerical Method For Simulation Of Quantum Transport In High Electron Mobility Transistor; Part Ii: The Full Quantum Transport, Rahim Khoie

Electrical & Computer Engineering Faculty Research

In Part I of this paper we reported a self-consistent Boltzmann-Schrodinger-Poisson simulator for HEMT in which only electrons in the first subband were assumed to be quantized with their motion restricted to 2 dimensions. In that model, the electrons in the second and higher subbands were treated as bulk system behaving as a 3 dimensional electron gas. In Part II of this paper, we extend our simulator to a self-consistent full-quantum model in which the electrons in the second subband are also treated as quantized 2 dimensional gas. In this model, we consider the electrons in the lowest two subbands …


Intelligent Control Of Vehicles: Preliminary Results On The Application Of Learning Automata Techniques To Automated Highway System, Cem Unsal, John S. Bay, Pushkin Kachroo Nov 1995

Intelligent Control Of Vehicles: Preliminary Results On The Application Of Learning Automata Techniques To Automated Highway System, Cem Unsal, John S. Bay, Pushkin Kachroo

Electrical & Computer Engineering Faculty Research

We suggest an intelligent controller for an automated vehicle to plan its own trajectory based on sensor and communication data received. Our intelligent controller is based on an artificial intelligence technique called learning stochastic automata. The automaton can learn the best possible action to avoid collisions using the data received from on-board sensors. The system has the advantage of being able to work in unmodeled stochastic environments. Simulations for the lateral control of a vehicle using this AI method provides encouraging results.


Flexible Low-Cost Automated Scaled Highway (Flash) Laboratory For Studies On Automated Highway Systems, Pushkin Kachroo, Kaan Ozbay, Robert G. Leonard, Cem Unsal Oct 1995

Flexible Low-Cost Automated Scaled Highway (Flash) Laboratory For Studies On Automated Highway Systems, Pushkin Kachroo, Kaan Ozbay, Robert G. Leonard, Cem Unsal

Electrical & Computer Engineering Faculty Research

This paper addresses the development of a flexible low-cost automated scale highway (FLASH) laboratory which is intended to serve as a catalyst for accelerating the development of many intelligent vehicle highway system (IVHS) concepts. It also highlights the significance of the laboratory for the research, evaluation, and testing of automated highway system (AHS) configurations, architectures, designs and technologies. This laboratory, using small scale standardized vehicles will serve as a test bed for the economical development and evaluation of various hardware, software, and management systems before full scale testing and deployment. The laboratory will provide the capability to test day and …


Comparison Of Time-Domain Reflectometry Performance Factors For Several Dielectric Geometries: Theory And Experiments, S. V. Maheshwarla, R. Venkatasubramanian, Robert F. Boehm Aug 1995

Comparison Of Time-Domain Reflectometry Performance Factors For Several Dielectric Geometries: Theory And Experiments, S. V. Maheshwarla, R. Venkatasubramanian, Robert F. Boehm

Electrical & Computer Engineering Faculty Research

We propose three nontraditional dielectric geometries and present an experimental and theoretical analysis and comparison of time domain reflectometry (TDR) performances for them. The traditional geometry (the probes inserted in material of essentially infinite extent) is compared to three nontraditional geometries where the probes are affixed outside of a core sample, inside of a bore, or flat on the surface of a semi-infinite solid. Our derivation relates the velocity of electromagnetic wave propagation to the complex permittivities and permeabilities of the media and the geometry for the three nontraditional configurations. Experimental results for air, styrofoam, dry sand, wet sand of …


A General Approach To Boolean Function Decomposition And Its Application In Fpgabased Synthesis, Tadeusz Luba, Henry Selvaraj Jan 1995

A General Approach To Boolean Function Decomposition And Its Application In Fpgabased Synthesis, Tadeusz Luba, Henry Selvaraj

Electrical & Computer Engineering Faculty Research

An effective logic synthesis procedure based on parallel and serial decomposition of a Boolean function is presented in this paper. The decomposition, carried out as the very first step of the .synthesis process, is based on an original representation of the function by a set of r-partitions over the set of minterms. Two different decomposition strategies, namely serial and parallel, are exploited by striking a balance between the two ideas. The presented procedure can be applied to completely or incompletely specified, single- or multiple-output functions and is suitable for different types of FPGAs including XILINX, ACTEL and ALGOTRONIX devices. The …


Variable Structure End Point Control Of A Flexible Manipulator, Shailaja Chenumalla, Sahjendra N. Singh Jul 1993

Variable Structure End Point Control Of A Flexible Manipulator, Shailaja Chenumalla, Sahjendra N. Singh

Electrical & Computer Engineering Faculty Research

We treat the question of control and stabilization of the elastic multibody system developed in the Phillips Laboratory, Edwards Air Force Base, California. The controlled output is judiciously chosen such that the zero dynamics are stable or almost stable. A variable structure control (VSC) law is derived for the end point trajectory control. Although, the VSC law accomplishes precise end point tracking, elastic modes are excited during the maneuver of the arm. A Linear stabilizer is designed for the final capture of the terminal state.


Measurement Of Thermal-Energy Charge-Transfer Rate Coefficient Of Mo6+ And Argon, Victor H.S. Kwong, Z. Fang, Yingtao Jiang, T. T. Gibbons, L. D. Gardner Jul 1992

Measurement Of Thermal-Energy Charge-Transfer Rate Coefficient Of Mo6+ And Argon, Victor H.S. Kwong, Z. Fang, Yingtao Jiang, T. T. Gibbons, L. D. Gardner

Electrical & Computer Engineering Faculty Research

The charge-transfer rate coefficient of Mo6+ and argon has been measured at mean ion energies of 8.8 and 1.4 eV using a laser-ablation ion source and an ion trap. The rate coefficient deduced from these measurements is 1.02(0.10)×10-10 cm3 s-1 and appears to be independent of the mean ion energy at this energy range. However, the measured value is an order of magnitude smaller than the Langevin rate coefficient.


Observation Of The Visible Absorption Spectrum Of H2o+, Biswajit Das, John W. Farley Jan 1991

Observation Of The Visible Absorption Spectrum Of H2o+, Biswajit Das, John W. Farley

Electrical & Computer Engineering Faculty Research

The Ã 2 Ã1X̃ 2 B̃1 system of H2O+ has been observed, using laser absorption spectroscopy in a velocity‐modulated discharge. A total of 78 transitions between 14 794 and 15 475 cm−1 have been observed with an uncertainty (1 SD) of 0.02 cm−1, including 76 transitions in the (0,7,0)–(0,0,0) band and 2 in the (0,8,0)–(0,0,0) band. This species is important for cometary astronomy, and intriguing for molecular physics because of its prominent Renner–Teller interaction. Careful measurements were made of the relative intensities of the absorption lines, …


Experimental Apparatus For Production, Cooling, And Storing Multiply Charged Ions For Charge-Transfer Measurements, Victor H. S. Kwong, T. T. Gibbons, Z. Fang, Jinhua Jiang, H. Knocke, Yingtao Jiang, B. Ruger, Su-Ching Huang, E. Braganza, W. Clark, L. D. Gardner Jul 1990

Experimental Apparatus For Production, Cooling, And Storing Multiply Charged Ions For Charge-Transfer Measurements, Victor H. S. Kwong, T. T. Gibbons, Z. Fang, Jinhua Jiang, H. Knocke, Yingtao Jiang, B. Ruger, Su-Ching Huang, E. Braganza, W. Clark, L. D. Gardner

Electrical & Computer Engineering Faculty Research

A novel method is described that combines the production of ions by laser ablation with an ion‐trap technique for the measurement of thermal‐energy charge‐transfer rates of multiply charged ions and neutrals. The charge‐transfer rate is determined by measuring the rate of loss of stored ions from the trap. Verification of the calibration of the apparatus is demonstrated through investigation of charge transfer of N2 and N2+, which has been studied by another group. We also have made the first measurement on the thermal‐energy charge‐transfer coefficient of Ar and W2+. The rate coefficient is 0.99(0.22)×10−11 …


On Implicational Dependency Families Possessing Finite Armstrong Relations, Kazem Taghva Aug 1989

On Implicational Dependency Families Possessing Finite Armstrong Relations, Kazem Taghva

Electrical & Computer Engineering Faculty Research

Let X ≠ 0 be a finite collection of nonempty relations over the relation scheme R(A1, A2 , ... , A,.); then the closure of X under embedding and direct product (up to isomorphism) is a finitely generated Implicational Dependency family (ID-family) generated by X. In this paper, we show that the class of finitely generated ID-families is identical to the class of those ID-families which possess a finite Armstrong relation.


On Purely Exponential Logic Queries, Kazem Taghva, Tian-Zheng Wu May 1988

On Purely Exponential Logic Queries, Kazem Taghva, Tian-Zheng Wu

Electrical & Computer Engineering Faculty Research

The recursive nature of logic programs has long been the subject of optimization techniques [2, 8]. Recently, the database community has taken interest in extending the expressive power of relational algebra by augmenting it with function-free Horn style logic queries. This extension has led to various optimization techniques [2, 6, 8]. It seems, almost invariably, these techniques are most efficient in the processing of linear recursive queries. Moreover, as the equivalence of nonlinear rules to linear rules in general is undecidable [3, 9], the best one can hope is to rewrite some nonlinear rules as linear rules. For this reason, …