Digital Commons Network^™

New Plane Wave Representation Of Point Sources, L. (Lijun) J. Jiang, W. C. Chew

Electrical and Computer Engineering Faculty Research & Creative Works

A new method to decompose the spherical wave of a 3D point source into plane waves is discussed. Using Cauchy's theorem, it represents spherical waves as the summation of surface-direction-wave integrals. Results show that only 6 directions waves needed storage. Thus, the method provides a good cost reduction for plane-wave related algorithms.

The Effects Of Corrosive Chemicals On Corrosion Rate Of Steel Reinforcement Bars: I. Swamp Water, Sulistyoweni Widanarko, Henki W. Ashadi, Andri Krisnadi Wicaksono

Makara Journal of Technology

Most of infrastructures using steel concrete to reinforce the strength of concrete. Steel concrete is so vulnerable to chemical compounds that can cause corrosion. It can happen due to the presence of chemical compounds in acid environment in low pH level. These chemical compounds are SO4 2-, Cl-, NO3 -. There are many swamp area in Indonesia. The acid contents and the concentration of ion sulphate, chlorides, and nitrate are higher in the swamp water than in the ground water .The objective of this research was to find out the influence of corrosive chemicals in the swamp water to the …

The Effects Of Corrosive Chemicals On Corrosion Rate Of Steel Reinforcement Bars: Ii. Swamp Sludges, Henki W. Ashadi, Sulistyoweni Widanarko, Irma Gusniani

Makara Journal of Technology

A polluted environment will influence the building age. The objective of this research was to find out the influence of corrosive chemicals within the sludge swamp area with the corrosion rate of steel concrete. Corrosion in steel concrete usually occur in acid area which contain of SO4 2-, Cl- and NO3 -. The research treatment used by emerging ST 37 and ST 60 within 60 days in ‘polluted’ sludge swamp area. Three variation of ‘polluted’ swamp sludge were made by increasing the concentration a corrosive unsure up to 1X, 5X and 10X. The corrosion rate measured by using an Immersion …

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 …

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.

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. …

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 …

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 …

Surface Switching Characteristics Of Variable Permittivity Dielectrics, Wayne Huebner, Eric J. Carleton

Materials Science and Engineering Faculty Research & Creative Works

Flashover voltage, lifetimes, and switch performance of insulators utilizing square thin and thick film electrodes were examined to determine the viability of using thin electrodes for reliable surface discharge switching. Gold, silver, and platinum were sputtered (0.25 µm) and screen printed (15 µm) onto Al₂O₃, TiO₂, and modified BaTiO₃ (MBT), then tested in air at 10⁵ Pa, under vacuum (10^-3/ torr), and while immersed in an insulating fluid, SF-2 (manufactured by 3M). For the measured range of 0.5 to 3 mm in air, the flashover voltage for all three insulators …

Bs News

Building Services Engineering

No abstract provided.

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.

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.

Phase I: Design And Analysis Of A Process For Melt Casting Metallic Fuel Pins Incorporating Volatile Actinides, Yitung Chen, Randy Clarksean, Darrell Pepper

Fuels Campaign (TRP)

The proposed research would be conducted in 3 phases. Each of the phases would be carried out over a one-year period. Phase I includes model development, analysis, and the selection of a new casting furnace design. The work discussed in this report was completed as Phase I. Phase II of the program will lead to more modeling and validation to evaluate the proposed furnace concept. Phase III would be a joint effort between UNLV and Argonne National Laboratory (ANL) to demonstrate the acceptable use of the new furnace in a simulated remote environment.

The Phase III work would include the …

Aligning Hierarchical Goals In An Organization: The Path From Training To Performance, Jeanette Denise Selby-Lucas

Engineering Management & Systems Engineering Theses & Dissertations

Training is a multi-billion-dollar industry, and with the advent of the training technology revolution and the possibilities it provides to business and government, as well as to the academic community, it is important to determine if the money invested in training by these communities is providing the expected performance on the part of those who are trained. This can be done by quantitatively evaluating the relationship between training and performance.

This study extends the scholarly literature by developing the concept of organizational alignment through a combination of Human Performance Technology literature and traditional engineering methodologies. Organizational training and performance is …

A Device For Surface Study Of Confined Micron Thin Films In A Total Internal Reflection Geometry, Sergey Mamedov, Alexander D. Schwab, Ali Dhinojwala

College of Polymer Science and Polymer Engineering

A device to probe the molecular structure of materials next to a solid interface in a thin film geometry has been developed. The device can produce controlled thicknesses as small as 1 mum with parallelity better than 0.003degrees. We have shown that the thickness and the parallelity of the film produced between two optical surfaces can be quantified using white light and monochromatic light interferometry, respectively. In addition, this apparatus allows the study of these films in a static state or under shear using spectroscopic techniques involving transmission or reflection measurements. (C) 2002 American Institute of Physics.

Low Concentration Microenvironments Enhance The Migration Of Neonatal Cells Of Glial Lineage, Richard A. Able, Jr., Celestin Ngnabeuye, Cade Beck, Eric C. Holland, Maribel Vazquez

Publications and Research

Glial tumors have demonstrated abilities to sustain growth via recruitment of glial progenitor cells (GPCs), which is believed to be driven by chemotactic cues. Previous studies have illustrated that mouse GPCs of different genetic backgrounds are able to replicate the dispersion pattern seen in the human disease. How GPCs with genetic backgrounds transformed by tumor paracrine signaling respond to extracellular cues via migration is largely unexplored, and remains a limiting factor in utilizing GPCs as therapeutic targets. In this study, we utilized a microfluidic device to examine the chemotaxis of three genetically-altered mouse GPC populations towards tumor conditioned media, as …

Turing Day : 90Ème Anniversaire De La Naissance De Alan Mathison Turing, Christof Teuscher

Electrical and Computer Engineering Faculty Publications and Presentations

A brief statement on the life work and significance of computing pioneer Alan Turing, on the 90th anniversary of his birth.

An Interactive Visual Environment For Scientific Problem Solving, Georg F. Mauer

Mechanical Engineering Faculty Research

Science and engineering students do not typically receive explicit training in scientific problem solving, i.e. applying science principles to specific situations. Students’ problem solving skills often show little improvement throughout their course of studies. This paper describes a structured, graphical, interactive (GUI) learning environment, which presents problems and tools for analysis in systematic and logical order, and encourages the student to develop the solution path in the manner of an experienced expert. The learning environment’s subject area is Engineering Dynamics, which was selected for its systematic structure and its early (usually sophomore) place in the undergraduate curriculum. The software presents …

Long-Term Benefits Of Stabilizing Soil Subgrades, Tommy C. Hopkins, Tony L. Beckham, Liecheng Sun, Bixian Ni, Barry Butcher

Kentucky Transportation Center Research Report

Chemical admixtures have been used extensively since the mid-eighties in Kentucky to improve bearing strengths of soil subgrades. Most pavements in Kentucky are constructed on clayey soils. Although short-term observations at a small number of sites showed that chemical stabilization worked very well, a need existed to perform a more comprehensive review and to assess the long-term benefits of this subgrade stabilization method. The main intent of this study was an attempt to address questions concerning bearing strengths, longevity, durability, structural credit, economics, and performance of pavements resting on soil subgrades mixed with chemical admixtures. In-depth field and laboratory studies …

Low Salinity Flooding In A Selected Carbonate Reservoir: Experimental Approach, Mohamed Yehia Mohamed Mahmoud

Theses

Low-salinity water flooding LoSal^TM has been used to improve oil recovery for many decades. Historically, the mechanisms behind this improvement in oil recovery were attributed to the pressure maintenance and displacement of oil by injected water, i.e. physical mechanism. Recently, evidence from laboratory and field tests indicated that water flooding also involves chemical processes and that modifying of the injection brine salinity and its ionic composition can significantly impact the oil recovery. Several theories regarding the mechanism of LoSal^TM flooding have been discussed in the literature. These include interfacial tension reduction, wettability alteration (cation exchange), change in pH …

Synthesis, Characterization And Applications Of Some Conducting Polymers, Fatma Yousif Mohamed Balhey

Theses

Conducting polymers emerged as a new class of materials by the end of the sixties. Since then many efforts have been made to put these materials to

industrial use. Among the achievements are their applications in the semiconductor industry, medical field, chemical and biological sensors, etc. A

different track that alleviated the prospects of the application of conducting

polymers is the modification of the polymer film, namely through the inclusion of metallic moieties for specific target usage. In this thesis the candidate aimed

to synthesis well established and extensively studied class of electrically conductive polymer, 3-methylthiophene. The polymer was then …

Incorporating Web-Based Homework Problems In Engineering Dynamics, Ralph E. Flori, David B. Oglesby, Timothy A. Philpot, Nancy E. Hubing, Richard H. Hall, Vikas Yellamraju

Geosciences and Geological and Petroleum Engineering Faculty Research & Creative Works

We are involved in a project funded by the Department of Education (FIPSE) which focuses on developing interactive software to improve the teaching and learning of engineering statics, dynamics, and mechanics of materials. This paper presents an overview of this project, discusses its objectives, and focuses on one particular aspect of the project.the use of web-based homework problems as assessment tools to evaluate student learning. The overall project includes creating, for all three engineering mechanics courses, the following web-based learning tools: (a) Animated theory modules, using Macromedia.s Flash development software, which display basic theory and example problems in an engaging, …

Experimental Studies Of Wave Propagation In Three-Dimensional Photonic Crystals, John M. Tobias

Dissertations

Photonic crystals were proposed fifteen years ago. Propagation is selectively prevented through these crystals resulting in a photonic band gap, that is, a frequency region where light cannot propagate. These frequency bands are analogous to electronic band gaps in solid-state crystals.

The optical properties of the photonic crystal in regions near the band gap remain relatively unexplored. Yet, there is significant evidence to suggest that this avenue of investigation can provide useful optical and microwave applications. Numerical studies have predicted that the effective permittivity near the photonic band gap approaches zero and becomes negative. Selfcollimation of the propagating beam and …

Development Of Icejet-Based Surface Processing Technology, Dimitri V. Shishkin

Dissertations

The objective of the proposed work is to acquire knowledge needed for the development and deployment of manufacturing processes utilizing the enormous technological potential of water ice. Material removal by blasting with ice media such as particles, pellets and slugs was investigated. The ice media was accelerated by entrainment in a fluid stream (air, steam, liquid water, supercritical C0₂), impact of rotating blades, fluid expansion, etc. The ice-airjet has to replace sand blasting and the ice-waterjet has to replace the abrasive waterjet. Based on these results, technical approaches for surface processing and machining will be improved. A primary …

Elasticity In Microstructure Sensitive Design Through The Use Of Hill Bounds, Benjamin L. Henrie

Theses and Dissertations

In engineering, materials are often assumed to be homogeneous and isotropic; in actuality, material properties do change with sample direction and location. This variation is due to the anisotropy of the individual grains and their spatial distribution in the material. Currently there is a lack of communication between the design engineer, material scientist, and processor for solving multi-objective/constrained designs. If communication existed between these groups then materials could be designed for applications, instead of the reverse. Microstructure sensitive design introduces a common language, a spectral representation, where both design properties and microstructures are expressed.

Using Hill bounds, effective elastic properties …

Modeling Corrosion In Oxygen Controlled Lbe Systems With Coupling Of Chemical Kinetics And Hydrodynamics-Phase Two, Samir Moujaes, Yitung Chen

Transmutation Sciences Materials (TRP)

The proposed work will combine chemical kinetics and hydrodynamics in target and test-loop lead-bismuth eutectic (LBE) systems to model system corrosion effects. This approach will result in a predicative tool that can be validated with corrosion test data, used to systematically design tests and interpret the results, and provide guidance for optimization in LBE system designs. The task includes two subtasks. The first subtask is to try to develop the necessary predictive tools to be able to predict the levels of oxygen and corrosion products close to the boundary layer through the use of Computational Fluid Dynamics (CFD) modeling. The …

Development Of A Systems Engineering Model Of The Chemical Separations Process, Yitung Chen, Darrell Pepper, Randy Clarksean

Separations Campaign (TRP)

Two activities are proposed: the development of a systems engineering model and the refinement of the Argonne code AMUSE (Argonne Model for Universal Solvent Extraction). The detailed systems engineering model will be the start of an integrated approach to the analysis of the materials separations associated with the AAA Program. A second portion of the project will streamline and improve an integral part of the overall systems model, which is the software package AMUSE. AMUSE analyzes the UREX process and other related solvent extraction processes and defines many of the process streams that are integral to the systems engineering model. …

Flexible Manufacturing System Utilizing Computer Integrated Control And Modeling, Yahia Mohammed Al-Smadi

Theses

In today's fast-automated production, Flexible Manufacturing Systems (FMS) play a very important role by processing a variety of different types of workpieces simultaneously. This study provides valuable information about existing FMS workcells and brings to light a unique concept called Programmable Automation.

Another integrated concept of programmable automation that is discussed is the use of two feasibility approaches towards modeling and controlling FMS operations; the most commonly used is programmable logic controllers (PLC), and the other one, which has not yet implemented in many industrial applications is Petri Net controllers (PN). This latter method is a unique powerful technique to …

Nanofatigue Studies Of Ultrathin Hard Carbon Overcoats Used In Magnetic Storage Devices, Xiaodong Li, Bharat Bhushan

Faculty Publications

A technique to perform nanofatigue experiments was developed. This technique utilizes a depth-sensing nanoindenter with harmonic force. The nanofatigue behavior of 20 nm thick amorphous carbon coatings was studied. The contact stiffness was monitored continuously throughout the test. The abrupt decrease in the contact stiffness indicates fatigue damage has occurred. The critical load amplitude, below which no fatigue damage occurs, was identified. It was found that the filtered cathodic arc coating exhibits longer fatigue life than a direct ion beam coating. Failure mechanisms of the coatings during fatigue are also discussed in conjunction with the hardness,elastic modulus, and fracture toughness, …

Genome-Wide Screening For Trait Conferring Genes Using Dna Microarrays, R. T. Gill, S. Wildt, Y. T. Yang, S. Ziesman, G. Stephanopoulos

Dartmouth Scholarship

We report a DNA microarray-based method for genome-wide monitoring of competitively grown transformants to identify genes whose overexpression confers a specific cellular phenotype. Whereas transcriptional profiling identifies differentially expressed genes that are correlated with particular aspects of the cellular phenotype, this functional genomics approach determines genes that result in a specific physiology. This parallel gene-trait mapping method consists of transforming a strain with a genomic library, enriching the cell population in transformants containing the trait conferring gene(s), and finally using DNA microarrays to simultaneously isolate and identify the enriched gene inserts. Various methods of enrichment can be used; here, genes …