Engineering Commons^™

University Of Nevada, Las Vegas Advanced Accelerator Applications University Participation Program: Quarterly Report, Third Quarter (September To November 2001), Anthony Hechanova

Transmutation Research Program Reports (TRP)

This Quarterly Report is a primary deliverable from the University of Nevada, Las Vegas (UNLV) Advanced Accelerator Applications (AAA) University Participation Program (UPP) Director to the U.S. Department of Energy (DOE) as described in the UNLV AAA proposal and Statement of Work for the Third Quarter.

The UNLV AAA UPP Director implements the program’s administration using staff from the Harry Reid Center for Environmental Studies (HRC) to ensure that work conducted under the UNLV AAA UPP meets program objectives. The UNLV AAA UPP consists of three components: Program Support, Research Infrastructure Augmentation, and Student Research.

Boron Carbide/N-Silicon Carbide Heterojunction Diodes, Shireen Adenwalla, P. Welsch, A. Harken, Jennifer I. Brand, A. Sezer, Brian W. Robertson

Nebraska Center for Materials and Nanoscience: Faculty Publications

The fabrication, initial structural characterization, and diode measurements are reported for a boron carbide/silicon carbide heterojunction diode. Current–voltage curves are obtained for operation at temperatures from 24 to 351 °C. Plasma-enhanced chemical-vapor deposition (PECVD) -deposited undoped boron carbide material is highly crystalline and consists of a variety of polytypes of boron carbide (BC) with crystal sizes as large as 110 nm. Crystal phases are similar to those for PECVD BC on Si but only partially match known boron and boron-rich BC phases.

Investigation Of Reflective Materials For The Solar Cooker, Florida Solar Energy Center, John Harrison

FSEC Energy Research Center®

A critical task in developing a solar cooker is to identify reflector materials that would be both suitable for this application as well as economical. FSEC has conducted an extensive search for available reflective materials. This has included contacting reflective materials manufacturers as well as national laboratories that are currently working with private industry in developing reflector that can be used primarily on large concentrating solar energy devices. This investigation used a variety of resources. These included the FSEC solar library, web search engines, solar industry catalogs and directories, personal contacts, aluminum industry sources, solar cooker discussion groups, and a …

Giant Photoresistivity And Optically Controlled Switching In Self-Assembled Nanowires, N. Kouklin, L. Menon, A. Z. Wong, Daniel W. Thompson, John A. Woollam, P. F. Williams, Supriyo Bandyopadhyay

Department of Electrical and Computer Engineering: Faculty Publications

We report the observation of giant photoresistivity in electrochemically self-assembled CdS and ZnSe nanowires electrodeposited in a porous alumina film. The resistance of these nanowires increases by one to two orders of magnitude when exposed to infrared radiation, possibly because of real-space transfer of electrons from the nanowires into the surrounding alumina by photon absorption. This phenomenon has potential applications in ‘‘normally on’’ infrared photodetectors and optically controlled switches.

Localization Of Carriers And Polarization Effects In Quaternary Alingan Multiple Quantum Wells, E. Kuokstis, J. Zhang, M.-Y. Ryu, J. W. Yang, Grigory Simin, M. Asif Khan, R. Gaska, M. S. Shur

Faculty Publications

We report on observing a long-wavelength band in low-temperature photoluminescence(PL)spectrum of quaternary Al_0.22In_0.02Ga_0.76N/Al_0.38In_0.01Ga_0.61N multiple quantum wells(MQWs), which were grown over sapphire substrates by a pulsed atomic-layer epitaxy technique. By comparing the excitation-power density and temperature dependence of the PLspectra of MQWs and bulk quaternary AlInGaN layers, we show this emission band to arise from the carrier and/or exciton localization at the quantum well interface disorders. PL data for other radiative transitions in MQWs indicate that excitation-dependent spectra position is determined by screening of the built-in electric field.

Nuclear Criticality Analyses Of Separations Processes For The Transmutation Fuel Cycle: Quaterly Report, William Culbreth, Pang Tao

Separations Campaign (TRP)

During the first quarter of the work, the tasks included training students in the use of Monte Carlo codes used in radiation transport studies and the assessment of neutron multiplication factors for specific problems outlined by ANL-East through Drs. Laidler and Vandegrift.

The proposal also included objectives for the first year of work on this project, as listed below. The work conducted in the first quarter of the project was in partial completion of these objectives.

• Train UNLV students in the use of SCALE and/or MCNP for the assessment of nuclear criticality.

• Assess neutron multiplication factor, k_{eff …}

Radiation Transport Modeling Of Beam-Target Experiments For The Aaa Project: Quaterly Report, William Culbreth

Reactor Campaign (TRP)

The national development of technology to transmute nuclear waste depends upon the generation of high energy neutrons produced by proton spallation. Proton accelerators, such as LANSCE at the Los Alamos National Laboratory, are capable of producing 800 MeV protons. By bombarding a lead/bismuth target, each proton may generate 500 or more neutrons that can activate fission products or induce the fission of transuranic isotopes.

The Monte Carlo radiation transport code MCNPX developed at LANL is an important tool in the design of transmuter technology. It must be validated, however, for the neutron energy that will be employed. Experiments are being …

Horses Damp The Spring In Their Step, Alan M. Wilson, M. Polly Mcguigan, Anne Su, Antonie J. Van Den Bogert

Mechanical Engineering Faculty Publications

The muscular work of galloping in horses is halved by storing and returning elastic strain energy in spring-like muscle–tendon units^{1, 2}.These make the legs act like a child's pogo stick that is tuned to stretch and recoil at 2.5 strides per second. This mechanism is optimized by unique musculoskeletal adaptations: the digital flexor muscles have extremely short fibres and significant passive properties, whereas the tendons are very long and span several joints^{3, 4}. Length change occurs by a stretching of the spring-like digital flexor tendons rather than through energetically expensive length changes in the muscle^{5 …}

Two-Dimensional Fast Evanescent Wave Algorithm, W. C. Chew, L. (Lijun) J. Jiang, S. Velamparambil

Electrical and Computer Engineering Faculty Research & Creative Works

A new fast evanescent wave algorithm (FEWA) is introduced in the two-dimensional (2-D) case. It expands the Green's function into propagating waves and directional evanescent waves. Applying the evanescent wave correction technique, a procedure similar to the traditional MLFMA can be expedited. No buffer region is necessary anymore, and fewer translators are needed. Numerical examples are given to show the features of this method.

Ultraviolet Light-Emitting Diodes At 340 Nm Using Quaternary Alingan Multiple Quantum Wells, V. Adivarahan, A. Chitnis, J. P. Zhang, M. Shatalov, J. W. Yang, Grigory Simin, M. Asif Khan, R. Gaska, M. S. Shur

Faculty Publications

An ultraviolet light-emitting diode with peak emission wavelength at 340 nm is reported. The active layers of the device were comprised of quaternary AlInGaN/AlInGaN multiple quantum wells, which were deposited over sapphire substrates using a pulsed atomic-layer epitaxy process that allows precise control of the composition and thickness. A comparative study of devices over sapphire and SiC substrates was done to determine the influence of the epilayer design on the performance parameters and the role of substrate absorption.

Testing Exception And Error Cases Using Runtime Fault Injection, James A. Whittaker, Florence E. Mottay, Ibrahim K. El-Far

Electrical Engineering and Computer Science Faculty Publications

Fault injection deals with the insertion or simulation of faults in order to test the robustness and fault tolerance of a software application. Such measures are generally performed on software that is mission critical, to the extent that failure could have significant negative ramifications. Actual injection of faults can be performed either at compile time, when additional code is inserted to force error conditions to evaluate to true, or at runtime during which faults are injected into the software's execution environment. This paper focuses on the latter type of fault injection and presents a new mechanism for inserting environmental faults. …

Hybrid Transient-Parametric Method And System To Distinguish And Analyze Sources Of Acoustic Emission For Nondestructive Inspection And Structural, Health Monitoring, Yuris Dzenis

Department of Mechanical and Materials Engineering: Faculty Publications

A nondestructive evaluation (NDE) technique for inspecting or health monitoring of Structures and/or Specimens by analyzing acoustic emission (AE) signals emitted by the Structures and/or specimens. The method and System ana lyzes acoustic emission (AE) signals emitted by structures and/or Specimens. AE Signals emitted by the Structures and/or Specimens are parametrically filtered as a function of parametric filters corresponding to characteristic waveforms of transient AE classes of predefined AE signals. In para metric analysis, the filtering may be pre- or post-recording. In transient AE analysis, the filtering may be prior to transient recording of the transient signals.

Survivable Mobile Operating System, James Whittaker, Mohommad Samarah

Electrical Engineering and Computer Science Faculty Publications

Although there is a large body of work on cryptographic techniques and algorithms that provide basic building blocks to solve specific security problems, relatively little work has been done in investigating security issues in mobile system contexts. Conventional security controls work well for static code, but break down with code mobility. In this paper, we investigate the need for end-to-end security in mobile and wireless operating systems. We study the implications of mobility - specifically, ways in which the operating system may facilitate communication security. We suggest a framework for designing security into mobile devices by building encryption into the …

Ua3/9/5 Partnerships For Progress: Linking Higher Education & Economic Development, Wku President's Office, Gary A. Ransdell

WKU Archives Records

Speech delivered by WKU president Gary Ransdell at the National Governor's Association Center for Best Practices. In response to Governor Patton's challenges to create Programs of Distinction and enhance the state's capacity for economic development, we, at Western, have created a series of applied science centers. These centers are directing faculty talent toward creating a relevant curriculum in the sciences, toward solving environmental and material problems which limit economic development, and toward creating practice-based experiences for students. A by-product of these centers is a strengthened core curriculum which brings the applied sciences into focus for all WKU students.

Aisi Standard For Cold-Formed Steel Framing -- Header Design, American Iron And Steel Institute

American Iron and Steel Institute (AISI) Specifications, Standards, Manuals and Research Reports (1946 - present)

The material contained herein has been developed by the American Iron and Steel Institute Committee on Framing Standards. The Committee has made a diligent effort to present accurate, reliable, and useful information on cold-formed steel framing design and installation. The Committee acknowledges and is grateful for the contributions of the numerous researchers, engineers, and others who have contributed to the body of knowledge on the subject. Specific references are included in the Header Standard document. With anticipated improvements in understanding of the behavior of cold-formed steel framing and the continuing development of new technology, this material may eventually become dated. …

Aisi Standard For Cold-Formed Steel Framing -- Truss Design, American Iron And Steel Institute

American Iron and Steel Institute (AISI) Specifications, Standards, Manuals and Research Reports (1946 - present)

The material contained herein has been developed by the American Iron and Steel Institute Committee on Framing Standards. The Committee has made a diligent effort to present accurate, reliable, and useful information on cold-formed steel framing design and installation. The Committee acknowledges and is grateful for the contributions of the numerous researchers, engineers, and others who have contributed to the body of knowledge on the subject. Specific references are included in the Truss Standard document. With anticipated improvements in understanding of the behavior of cold-formed steel framing and the continuing development of new technology, this material may eventually become dated. …

Institutsdagen At The Royal Institute Of Technology, Stockholm, Sweden, May 3, 2000, Otto Vogl, Ann Christine Albertsson

Emeritus Faculty Author Gallery

No abstract provided.

Evaluation Of A Threshold-Based Model Of The Elevated-Temperature Fatique Of Impact-Damaged Γ-Tial, Trevor S. Harding, J. Wayne Jones

Materials Engineering

Step-loading fatigue tests have been conducted on two γ-TiAl alloys with differing microstructures following quasi-static indentations intended to simulate assembly-related impact damage to low-pressure turbine blades. Fatigue tests were conducted at 600 °C using computer-controlled servohydraulic loading at a frequency of 20 Hz. Reasonably good agreement was achieved between the fatigue data and calculated fatigue strength based on the fatigue threshold and measured impact severity. In certain cases, the fatigue threshold model fails to completely describe the data. These discrepancies may be related to residual stresses, variations in crack-shape morphology, and small-crack effects. Residual stresses could not be directly measured, …

A Theory Of Volumetric Growth For Compressible Elastic Biological Materials, Stephen M. Klisch, Timothy J. Van Dyke, Anne Hoger

Mechanical Engineering

A general theory of volumetric growth for compressible elastic materials is presented. The authors derive a complete set of governing equations in the present configuration for an elastic material undergoing a continuous growth process. In particular, they obtain two constitutive restrictions from a work-energy principle. First, the authors show that a growing elastic material behaves as a Green-elastic material. Second, they obtain an expression that relates the stress power due to growth to the rate of energy change due to growth. Then, the governing equations for a small increment of growth are derived from the more general theory. The equations …

Statistics Of Sdf-System Estimate Of Roof Displacement For Pushover Analysis Of Buildings, Anil K. Chopra, Rakesh K. Goel, Chatpan Chintanapakdee

Civil and Environmental Engineering

Investigated in this report is the basic premise that the roof displacement of a multistory building can be determined from the deformation of an SDF system. For this purpose, the response of both systems is determined rigorously by nonlinear response history analysis, without introducing any of the approximations underlying the simplified methods for estimating the deformation of an SDF system (see, e.g., FEMA-273 or ATC-40 guidelines). The statistics of the SDF-system estimate of roof displacement are presented for a variety of building frames and six SAC buildings subjected to ground motion ensembles.

Two sets of structural systems and ground motions …

Determination Of Thickness Of Smooth Geomembranes, Nazli Yesiller, Arif Cekic

Civil and Environmental Engineering

Tests were conducted to determine thickness of smooth, nonreinforced geomembranes using three methods: mechanical (according to ASTM and European standards), ultrasonic, and magnetic methods. The mechanical method is the standard procedure used for determining thickness of geomembranes. The ultrasonic and magnetic methods are not commonly used for geomembranes; however, they are used for testing other materials such as metals. Tests were conducted on 15 geomembranes representing five types of polymers (HDPE, LLDPE, PVC, PP, and EPDM). The results of the testing program indicated that the level of pressures applied affected the thickness measurements in mechanical tests. While the low pressures …

Evaluation Of Drip And Microsprayer Irrigation Systems In California's Central Valley, Charles M. Burt

BioResource and Agricultural Engineering

No abstract provided.

Projection-Based Image Registration In The Presence Of Fixed-Pattern Noise, Ernest Armstrong, Stephen C. Cain, Majeed M. Hayat

Electrical and Computer Engineering Faculty Research and Publications

A computationally efficient method for image registration is investigated that can achieve an improved performance over the traditional two-dimensional (2-D) cross-correlation-based techniques in the presence of both fixed-pattern and temporal noise. The method relies on transforming each image in the sequence of frames into two vector projections formed by accumulating pixel values along the rows and columns of the image. The vector projections corresponding to successive frames are in turn used to estimate the individual horizontal and vertical components of the shift by means of a one-dimensional (1-D) cross-correlation-based estimator. While gradient-based shift estimation techniques are computationally efficient, they often …

Spectroscopic Ellipsometry And Electrical Studies Of As-Grown And Rapid Thermal Oxidized Si1−X−YGeXCY Films, W. K. Choi, W. Feng, L. K. Bera, Cary Y. Yang, J. Mi

Electrical and Computer Engineering

Transmission electron microscopy results showed the formation of SiC precipitation in a rapid thermally oxidized (RTO) Si_1−x−yGe_xC_y sample with high-C content. The spectroscopic ellipsometry results showed that the E₁ gap increased and E₂ gap decreased as the C concentration increased. For the oxidized samples, the amplitude of the E₂ transitions reduced rapidly and the E₁ transition shifted to a lower energy. The reduction in the E₂ transitions was due to the presence of the oxide layer. A high-Ge content layer and the low-C content in the RTO films accounted for …

Acuta Enews December 2001, Vol.30, No. 12

ACUTA Newsletters

In This Issue

Michigan Tech Chooses Network Appliances

ACUTA Events

The "New Member Roundup"- Why It's Important

DC Update

ACUTA EVENTS

Mexico Dialing Pattern Change

Did the Lights Go Out? Events, Results, and Impacts

Board Report

Thanks to Our Sponsors!

Fourth Quarter 2001 Web Sites to See

Welcome New Members

Positions Available

Statistical And Dempster-Shafer Techniques In Testing Structural Integrity Of Aerospace Structures, Roberto A. Osegueda, Seetharami R. Seelam, Ana C. Holguin, Vladik Kreinovich, Chin-Wang Tao, Hung T. Nguyen

Departmental Technical Reports (CS)

We describe the existing statistics-related methods of testing structural integrity for aerospace structures, describe their drawbacks, how they can be overcome, and compare the resulting techniques.

From Planning To Searching For The Shortest Plan: An Optimal Transition, Raul A. Trejo, Joel Galloway, Charanjiv Sachar, Vladik Kreinovich, Chitta Baral, Le Chi Tuan

Departmental Technical Reports (CS)

Since Kautz and Selman's 1992 ECAI paper on satisfiability based planning, there has been several work on planning through finding models of a logical theory. Most of these works focus on finding a plan of a given length. If we want to find the shortest plan, then usually, we try plans of length 1, 2, ..., until we find the first length for which such a plan exists. When the planning problem is difficult and the shortest plan is of a reasonable length, this linear search can take a long time; to speed up the process, it has been proposed …

Deconvolution Of Chirp Sidescan Sonar Data, Juliette W. Ioup, Maria T. Kalcic, Dale Bibee, Edit J. Kaminsky, George E. Ioup

Electrical Engineering Faculty Publications

No abstract provided.

Multimedia Web-Based Resources For Engineering Education: The Media Design And Assessment Laboratory At Umr, Vicki M. Eller, Steve Eugene Watkins, Richard H. Hall, Joel Balestra, Asha S. Rao

Business and Information Technology Faculty Research & Creative Works

The Design, Development, and Assessment of Web-Based Multimedia Learning Resources Are Important Aspects of Engineering Education. the Media Design and Assessment Laboratory at the University of Missouri-Rolla Was Established to Facilitate the Interaction between Web Designers and Content Providers. It Was Created under the Auspices of the Instructional Software Development Center. This Paper Will Discuss Design Philosophy in Terms of the Identification of Fundamental Concepts, Development Steps, and Assessment Implementation within the Context of Ongoing Projects. These Projects Include Modules for an Optics Curriculum, Tutorials for an Interdisciplinary Course, and Interactive Software for a Basic Engineering Course.

Pulmonary Arterial Morphometry From Microfocal X-Ray Computed Tomography, Kelly L. Karau, Robert C. Molthen, Anita H. Dhyani, Steven Thomas Haworth, Christopher C. Hanger, David L. Roerig, Roger H. Johnson, Christopher A. Dawson

Biomedical Engineering Faculty Research and Publications

The objective of this study was to develop an X-ray computed tomographic method for pulmonary arterial morphometry. The lungs were removed from a rat, and the pulmonary arterial tree was filled with perfluorooctyl bromide to enhance X-ray absorbance. At each of four pulmonary arterial pressures (30, 21, 12, and 5.4 mmHg), the lungs were rotated within the cone of the X-ray beam that was projected from a microfocal X-ray source onto an image intensifier, and 360 images were obtained at 1° increments. The three-dimensional image volumes were reconstructed with isotropic resolution with the use of a cone beam reconstruction algorithm. …