Engineering Commons^™

Quality Enhancement Of Reconfigurable Multichip Module Systems By Redundancy Utilization, Minsu Choi, Nohpill Park, Fabrizio Lombardi, Vincenzo Piuri

Electrical and Computer Engineering Faculty Research & Creative Works

This paper evaluates the quality effectiveness of redundancy utilization in reconfigurable multichip mode (RMCM) systems. Due to reconfigurability, the RMCM system can implement a device with different redundancy levels. A redundancy level is determined by the requirement of fault tolerance (FT) of the device under implementation which can be realized through reconfiguration. No previous work has adequately investigated the effect of utilization of redundancy on the quality-level (QL) of RMCM. In this paper, the tolerance to escape from testing is also introduced to provide more extensive and comprehensive analysis and is referred to as escape tolerance (ET). This can be …

External Parasitic Inductance In Microstrip And Stripline Geometries Of Finite Size, Marina Koledintseva, James L. Drewniak, Thomas Van Doren, David M. Hockanson

Electrical and Computer Engineering Faculty Research & Creative Works

An external parasitic ground (return) plane inductance, or a mutual inductance associated with fringing magnetic fields in planar transmission line structures, is the culprit of common-mode voltage (ground plane noise) that leads to parasitic radiation of the corresponding unintentional "antennas" in high-speed electronic equipment. Mutual inductance of this sort in microstrip and stripline structures is studied here using an analytical quasi- magnetostatic approach and FDTD modeling. Closed-form expressions for mutual inductance in symmetrical and asymmetrical microstrip and stripline structures are presented.

Nebraska Initiative For Aerospace Research And Industrial Development (Niarid): Final Report, Brent D. Bowen, Uno Aviation Institute

Faculty Books and Monographs

UNOAI Report 02-1

The Nebraska Initiative for Aerospace Research and Industrial Development (NIARID) was designed to accelerate the state’s efforts to expand its capacity, national competitiveness, and infrastructure in aerospace research and industry. The systemic goal of the NIARID was to strengthen Nebraska’s long-term ability to develop new, and strengthen current, aerospace research activities that increase the state’s national research competitiveness, foster sustainable growth in aerospace-related industry and the state’s economic development; complement the mission and activities of the Nebraska Space Grant Consortium (NSGC); and advance the goals of NASA and its enterprises. Funding from NIARID accelerated the establishment of …

Corrosion Of Steel By Lead Bismuth Eutectic: Quarterly Report For May-June-July 2002, John Farley

Transmutation Sciences Materials (TRP)

The goal of this project is to understand the basic science of corrosion in the steel/LBE system.

We are taking more data, typically using the newly installed X-ray Photoelectron Spectrometry (XPS) apparatus, and analyzing our existing data. Undergraduate students Denise Parsons and Julia Manzerova have helped a great deal in the analysis of the data. We can obtain the elemental composition as a function of position within the sample. This gives clues to the migration of materials, the composition of the protective oxide layer, and the basic science of the corrosion process. We found dramatic differences between the exposed and …

An Introductory Digital Design Course Using A Low–Cost Autonomous Robot, Tyson S. Hall, Kimberly E. Newman, James O. Hamblen

Faculty Works

This paper describes a new digital design laboratory developed for undergraduate students in this electrical and computer engineering curriculum. A top-down rapid prototyping approach with commercial computer-aided design tools and field-programmable logic devices (FPLDs) is used for laboratory projects. Students begin with traditional transistor–transistor logic-based projects containing a few gates and progress to designing a simple 16-bit computer, using very high-speed integrated circuits hardware description language (VHDL) synthesis tools and an FPLD. To help motivate students, the simple computer design is programmed to control a small autonomous robot with two servo drive motors and several sensors. The laboratory concludes with …

Organizing And Personalizing Intelligence Gathering From The Web, Hwee-Leng Ong, Ah-Hwee Tan, Jamie Ng, Pan Hong, Qiu-Xiang Li

Research Collection School Of Computing and Information Systems

In this paper, we describe how an integrated web‐based application, code‐named FOCI (Flexible Organizer for Competitive Intelligence), can help the knowledge worker in the gathering, organizing, tracking and dissemination of competitive intelligence (CI). It combines the use of a novel user‐configurable clustering, trend analysis and visualization techniques to manage information gathered from the web. FOCI allows its users to define and personalize the organization of the information clusters according to their needs and preferences into portfolios. These personalized portfolios created are saved and can be subsequently tracked and shared with other users. The paper runs through an example to show …

Modification Of All-Hexadedral Finite Element Meshes By Dual Sheet Insertion And Extraction, Michael J. Borden

Theses and Dissertations

The development of algorithms that effectively modify all-hexahedral finite element mesh is currently an active area of research. Mesh modification can be used to improve mesh quality reduce the time required to mesh a model, and improve the finite element analysis results. However, general modification of all-hexahedral meshes has proven difficult because of the global effects of local modifications. This thesis explains the global constraints on modifying all-hexahedral meshes and then presents three mesh modification techniques that make it possible to do local modifications while accounting for the global effects. These techniques are sheet insertion, sheet extraction, and mesh cutting. …

Fdtd Analysis Of Printed Circuit Boards Containing Wideband Lorentzian Dielectric Dispersive Media, Marina Koledintseva, David Pommerenke, James L. Drewniak

Electrical and Computer Engineering Faculty Research & Creative Works

A Lorentzian model as the general case of a frequency-dependent behavior of a dispersive dielectric material is considered in this paper. Recursive convolution algorithms for the finite-difference time-domain (FDTD) technique for two cases of a Lorentzian medium, narrowband and wideband, depending on the ratio of a resonance line half-width at -3 dB and the resonance frequency of the material, are detailed. It is shown that a wideband Lorentzian model of a dielectric FR-4 used in printed circuit boards is more flexible and gives good agreement with experimental curves, and may be preferable as compared to a Debye model.

Adaptive Neural Network Identifiers For Effective Control Of Turbogenerators In A Multimachine Power System, Ganesh K. Venayagamoorthy, Ronald G. Harley, Donald C. Wunsch

Electrical and Computer Engineering Faculty Research & Creative Works

This paper provides a novel method for nonlinear identification of multiple turbogenerators in a five-machine 12-bus power system using continually online trained (COT) artificial neural networks (ANNs). Each turbogenerator in the power system is equipped with all adaptive ANN identifier, which is able to identify/model its particular turbogenerator and rest of the network to which it is connected from moment to moment, based on only local measurements. Each adaptive ANN turbogenerator can be used in the design of a nonlinear controller for each turbogenerator in a multimachine power system. Simulation results for the adaptive ANN identifiers are presented

Alternatives To Gaskets In Shielding An Enclosure, Federico Centola, David Pommerenke, James L. Drewniak, Xiao Kai

Electrical and Computer Engineering Faculty Research & Creative Works

It is well known that a properly placed conductive gasket can complete an enclosure to yield good shielding. But often there are reasons, e.g. control of mechanical dimensions that this cannot be achieved. For these cases, one may want to avoid using a gasket that requires contacts. This paper will analyze alternatives to continuously contacting gaskets such as overlap structures, overlapping structures with different lossy and non-lossy materials, and overlaps with grounding points. It will compare structures by sufficient shielding for a typical class B product, high frequency (1-3 GHz) and low frequency (below 1 GHz) performance.

Application Of Higher-Order Fem Elements To The Analysis Of Microstrip Structures, H. Wang, C. L. Guo, Todd H. Hubing, James L. Drewniak, Thomas Van Doren, Richard E. Dubroff

Electrical and Computer Engineering Faculty Research & Creative Works

Microstrip structures, formed by metal traces printed on a dielectric substrate above a reference plane, are frequently the object of electromagnetic modeling. In this paper, hybrid FEM/MoM formulations employing conventional Whitney elements and newly developed linear-tangent/linear-normal (LT/LN) tangential vector finite elements (TVFEs) are applied to the analysis of microstrip structures with thin traces. This paper shows that the variation of the electric field below the trace is a significant issue to be addressed in microstrip structure modeling. Different mesh methods are investigated and the advantages of the LT/LN TVFEs are discussed.

Bs News

Building Services Engineering

No abstract provided.

On Using The Equivalent Conductivity To Characterize Solute Spreading In Environments With Low-Permeability Lenses, Andrew J. Guswa, David L. Freyberg

Engineering: Faculty Publications

Solute transport through highly heterogeneous geologic environments with connected pathways through high-conductivity material and lenses of low permeability often is not described well by a macroscopic advection-dispersion equation. An upscaled advection-dispersion model with a uniform velocity and dispersion coefficient does not predict the significant plume asymmetry and extended tailing often observed over finite distances in such environments. We investigate the hydrogeologic conditions under which an upscaled model must incorporate another mechanism to describe the extended tailing arising from slow advection through and diffusion into and out of low-permeability inclusions. We use high-resolution simulations to determine ground truth transport results for …

Low-Loss High Power Rf Switching Using Multifinger Algan/Gan Moshfets, Alexei Koudymov, Xuhong Hu, Kirill Simin, Grigory Simin, Mohammod Ali, Jinwei Yang, M. Asif Khan

Faculty Publications

We demonstrate a novel RF switch based on a multifinger AlGan/GaN MOSHFET. Record high saturation current and breakdown voltage, extremely low gate leakage current and low gate capacitance of the III-N MOSHFETs make them excellent active elements for RF switching. Using a single element test circuit with 1-mm wide multifinger MOSHFET we achieved 0.27 dB insertion loss and more than 40 dB isolation. These parameters can be further improved by impedance matching and by using submicron gate devices. The maximum switching power extrapolated from the results for 1a/mm 100 mum wide device exceeds 40 W for a 1-mm wide 2-a/mm …

Sum Normal Optimization Of Fuzzy Membership Functions, Daniel J. Simon

Electrical and Computer Engineering Faculty Publications

Given a fuzzy logic system, how can we determine the membership functions that will result in the best performance? If we constrain the membership functions to a certain shape (e.g., triangles or trapezoids) then each membership function can be parameterized by a small number of variables and the membership optimization problem can be reduced to a parameter optimization problem. This is the approach that is typically taken, but it results in membership functions that are not (in general) sum normal. That is, the resulting membership function values do not add up to one at each point in the domain. This …

Viewpoint: Experimental Recovery Of Geometrically Necessary Dislocation Density In Polycrystals, Brent L. Adams, Bassem S. El-Dasher, Anthony D. Rollett

Faculty Publications

The authors wish to thank The Alcoa Technical Research Center for supplying the specimens and performing the compression tests. This work was supported primarily by the MRSEC program of the National Science Foundation under DMR-0079996. Application of electron backscattering diffraction methods to recover estimates of the geometrically necessary dislocation density is described. The limitations of the method arising from the opacity of crystalline materials and the spatial and angular resolution limits are discussed.

Design And Analysis For Melt Casting Metallic Fuel Pins Incorporating Volatile Actinides, Xiaolong Wu

UNLV Theses, Dissertations, Professional Papers, and Capstones

Fundamental issues related to the selection of a metallic fuel casting furnace design are presented and discussed including heating mechanisms, casting issues, crucible design, and issues related to the mass transport of americium. The process of evaluating all of these different criteria is undertaken to select a concept that would have the greatest chance of success for casting americium in a metallic fuel rod. Based on this evaluation process, a concept for the casting of metallic fuel pins containing high vapor pressure materials is selected and discussed. The important physics of this concept include mass transport of americium from the …

Modeling And Simulation Of The Chemical Etching Process In Niobium Cavities, Qin Xue

UNLV Theses, Dissertations, Professional Papers, and Capstones

Niobium Cavities are important parts of the integrated NC/SC high-power linear accelerator (linac) that can accelerate over 100 mA of protons to several GeV. Surface finish of the niobium cavity plays an important role of achieving the best performance of niobium cavity. The chemical etching techniques have been widely used.

Chemical etching of the inner surface of the cavity is achieved by circulating acid through it. The acid interacts with the surface and eliminates imperfections. During the etching process, a pipe with baffles is inserted within the cavity to direct the flow along the surfaces.

A 2-D, axisymmetric, steady state, …

Experimental Demonstration Of Multiple Robot Cooperative Target Intercept, Timothy W. Mclain, Randal W. Beard, Jed M. Kelsey

Faculty Publications

This paper presents experimental results for the simultaneous intercept of preassigned targets by a team of mobile robots. The robots are programmed to mimic the dynamic behavior of unmanned air vehicles in constant-altitude flight. In proceeding to their targets, robots must avoid both known static threats and pop-up threats. An overview of the cooperative control strategy followed is given, as well as a description of the robot hardware and software used. Experimental results demonstrating simultaneous intercept of targets by the robot team are presented.

Developing A Sensing System For The Measurement Of Oxygen Concentration In Liquid Pb-Bi Eutectic: Quarterly Progress Report (May 01 – July 31, 2002), Yingtao Jiang, Bingmei Fu, Woosoon Yim

Transmutation Sciences Materials (TRP)

Accurate measurement of the oxygen concentration in liquid Lead-Bismuth Eutectic (LBE) cooling system is critical in the active control of the corrosion at the interface between LBE and the stainless steel of transport tubes. Currently, LANL (Los Alamos National Laboratory) scientists have employed an automobile-style YSZ (Yttria Stabilized Zirconia) oxygen sensor unit to measure oxygen levels in an engineeringscaled LBE test system. Although the theoretical model for calculating oxygen concentration based on voltage measurement of YSZ sensor in static conditions is well understood, there is an urgent and strong need to obtain a complete set of calibration curves for YSZ …

Unicode Compression: Does Size Really Matter?, Ryan Stansifer, Steve Atkin

Electrical Engineering and Computer Science Faculty Publications

The Unicode standard provides several algorithms, techniques, and strategies for assigning, transmitting, and compressing Unicode characters. These techniques allow Unicode data to be represented in a concise format in several contexts. In this paper we examine several techniques and strategies for compressing Unicode data using the programs gzip and bzip. Unicode compression algorithms known as SCSU and BOCU are also examined. As far as size is concerned, algorithms designed specifically for Unicode may not be necessary.

Survey Of Hydrogen Sulfide Concentrations In Vicinity Of Beef Cattle Feedlots, Richard K. Koelsch, Bryan L. Woodbury, David E. Stenberg, Daniel N. Miller, Dennis D. Schulte

Department of Agricultural and Biological Systems Engineering: Presentations and White Papers

A field survey of Total Reduced Sulfur (TRS) concentrations in the vicinity of beef cattle feedlots was conducted to compare field observations against current regulatory thresholds. In addition, environmental factors that may contribute to increased TRS emissions were evaluated. It was observed that TRS levels in the vicinity of beef cattle feedlots are not likely to exceed current regulatory thresholds used by mid-western states. It was further noted that concentration of TRS varies with air temperature and time of day. However, wet feedlot surface conditions and wind speed had almost no impact upon observed concentrations.

44th Rocky Mountain Conference On Analytical Chemistry

Rocky Mountain Conference on Magnetic Resonance

Final program, abstracts, and information about the 44th annual meeting of the Rocky Mountain Conference on Analytical Chemistry, co-endorsed by the Colorado Section of the American Chemical Society and the Society for Applied Spectroscopy. Held in Denver, Colorado, July 28 - August 1, 2002.

Integrating Local Search And Network Flow To Solve The Inventory Routing Problem, Hoong Chuin Lau, Q Liu, H. Ono

Research Collection School Of Computing and Information Systems

The inventory routing problem is one of important and practical problems in logistics. It involves the integration of inventory management and vehicle routing, both of which are known to be NP-hard. In this paper, we combine local search and network flows to solve the inventory management problem, by utilizing the minimum cost flow sub-solutions as a guiding measure for local search. We then integrate with a standard VRPTW solver to present experimental results for the overall inventory routing problem, based on instances extended from the Solomon benchmark problems.

Nanosat One Critical Design Review: Final Review - Part 3, Robert J. Twiggs, Jonathan How, Christopher Kitts

Robert "Bob" Twiggs STEM Education Collection

A PowerPoint Presentation created by Jonathan How, Christopher Kitts, and Bob Twiggs titled "Nanosat One Critical Design Review: Final Review - Part 3" from July 23, 2002.

Poly (1-Trimethysilyl-1-Propyne) Membrane Regeneration Process, Andrei G. Fadeev, Michael M. Meagher

Department of Chemical and Biomolecular Engineering: Faculty Publications

A novel process for the regeneration of PTMSP membranes is disclosed. The regeneration process includes washing a fouled PTMSP membrane with a solution containing at least about 50% butanol in water for a time sufficient to increase the flux and/or selectivity of the membrane. This regeneration process with a butanol containing solution significantly improves both the flux and selectivity of the PTMSP membrane and can regenerate the flux of the PTMSP membrane to the level of a previously unused membrane.

Subsystems & Components Review: Final Review - Part 2, Robert J. Twiggs

Robert "Bob" Twiggs STEM Education Collection

A PowerPoint Presentation created by Professor Bob Twiggs titled "Subsystems & Components Review: Final Review - Part 2" from July 23, 2002.

Water Delivery Service As A Determinant Of Irrigation Project Performance, Stuart W. Styles, M. A. Marino

BioResource and Agricultural Engineering

Performance of an irrigation system is represented by its measured levels of achievement in terms of one or several parameters that are chosen as indicators of the system’s goals. The purpose of this paper is to utilize and refine a set of evaluation indicators that can be used to describe the irrigation performance for sixteen international irrigation projects in less-developed countries. The irrigation performance of many international irrigation projects in less-developed countries has been reported as poor. The cause of the poor irrigation performance has been blamed on technical, financial, managerial, social, and/or institutional causes. This study is specifically designed …

Fluoride Release From Model Glass Ionomer Cements, A. Guida, R. G. Hill, Mark R. Towler, S. Eramo

Chemical and Biochemical Engineering Faculty Research & Creative Works

Glass ionomer cements (GICs) are an important class of biomedical material used extensively for color matched mercury free, dental restorations. GICs can release clinically beneficial amounts of fluoride and have acceptable handling properties which make them suitable as dental restoratives. The fluoride release of model GICs produced from specially synthesized fluoro-alumino-silicate glasses was studied. Nine glasses of varying fluoride content based on 4.5SiO₂-3Al₂O₃-1.5P₂O₅-(5-Z)CaO-ZCaF₂ were synthesized, and cement disks were prepared from them. The glass transition temperature reduced with increasing fluorine content of the glass. Fluoride ion release was measured …

A Preliminary Study Of An Aluminum-Free Glass Polyalkenoate Cement, Mark R. Towler, C. M. Crowley, D. Murphy, A. M.C. O'Callaghan

Chemical and Biochemical Engineering Faculty Research & Creative Works

No abstract provided.