Physical Sciences and Mathematics Commons^™

Magnetochemical Origin For Invar Anomalies In Iron-Nickel Alloys, V. Crisan, P. Entel, H. Ebert, H. Akai, Duane D. Johnson, J. B. Staunton

Duane D. Johnson

Zero- and finite-temperature (T) first-principles calculations versus composition (c) show that magnetochemical effects lead to Invar anomalies in Fe-(Ni, Co, Pt) alloys. Chemical short- or long-range order and negative interatomic exchange interaction of electrons in antibonding majority-spin states force the face-centered-cubic lattice to compete simultaneously for a smaller volume (from antiferromagnetic tendencies) and a larger volume (from Stoner ferromagnetic tendencies). The resulting additional negative lattice anharmonicity is very large for Fe-(Ni, Co) while absent for Fe-Pt. Our results explain the T- and c-dependent behavior of Invar properties, including the lattice softening and thermal expansion of Fe-Ni. In addition, the occurrence …

Comparison Of Water Quality, Zooplankton Density, And Cover In Razorback Sucker (Xyrauchen Texanus [Abbott]) Spawning Areas Of Lake Mead And Lake Mohave, Michael E. Golden, Paul B. Holden, Southern Nevada Water Authority

Publications (WR)

Las Vegas Bay and Echo Bay in Lake Mead have small, self-sustaining populations of razorback sucker (Xyrauchen texanus [Abbot]). Increased productivity and cover have been hypothesized as reasons for successful recruitment of razorback sucker in Lake Mead. Conversely, reproduction has been documented on Lake Mohave, another lower Colorado River reservoir, but no recruitment has been observed. In 2000, BIO-WEST, Inc. was contracted by the Southern Nevada Water Authority to design and implement a study to examine nutrient levels, zooplankton density, and cover in areas with and without razorback sucker recruitment success. We sampled Echo Bay, Las Vegas Bay, and …

Genetic Optimization Of A Tensegrity Structure, Jaime R. Taylor

Physics Faculty Research

Marshall Space Flight Center (MSFC) is charged with developing advanced technologies for space telescopes. The next generation of space optics will be very large and lightweight. Tensegrity structures are built of compressive members (bars), and tensile members (strings). For most materials, the tensile strength of a longitudinal member is larger than its buckling strength; therefore a large stiffness to mass ratio can be achieved by increasing the use of tensile members. Tensegrities are the epitome of lightweight structures, since they take advantage of the larger tensile strength of materials. The compressive members of tensegrity structures are disjoint allowing compact storage …

Compression Performance Of Jpeg Encryption Scheme, C. Kailasanathan, R. Safavi-Naini, P. Ogunbona

Faculty of Informatics - Papers (Archive)

Recent development in the Internet and Web based technologies require faster communication of multimedia data in a secure form. A number of encryption schemes for MPEG have been proposed. In this paper, we evaluate the compression performance of JPEG which has been encrypted with the zig-zag permutation algorithm, suggest a security enhancement to the scheme, and propose an alternative to entropy coding recommended by JPEG to compensate for the compression drop occurring due to permutation.

Scwds Briefs: Volume 18, Number 2 (July 2002)

Southeastern Cooperative Wildlife Disease Study: Publications

• Chronic wasting disease (CWD) recently has been identified in more free-ranging and captive cervids at additional locations in New Mexico, Wisconsin, and Colorado.
• An outbreak of low pathogenicity avian influenza (LPAI) virus apparently has been contained in domestic poultry in the Shenandoah Valley of Virginia.
• West Nile Virus Continues to Spread
• Update on Cryptosporidium and Giardia in Wildlife
• The accurate diagnosis of epizootic hemorrhagic disease virus (EHDV) in white-tailed deer
• In June of 2002, the Disney Wildlife Conservation Fund made a contribution to help support SCWDS' continuing investigations of avian vacuolar myelinopathy (AVM).
• …

A Study Of Various Thermodynamic And Wind Variables Associated With Tornadic Supercells Exhibiting Atypical Motion, Aaron Johnson

United States Department of Commerce: Staff Publications

Recent research into supercells has focused on narrowing the number of important storm processes that lead to these storms. For years it has been known that supercells generally deviate slightly to the left or right of the mean wind, but that in some rare cases, supercells move in a very atypical direction. For example, Corfidi (1998) examined the conditions present for the Jarrell, Texas tornado, which exhibited such an atypical motion, and found the environment to be extremely unstable with weak storm-relative helicity. He also found that the southwest movement of the Jarrell, TX storm was closely tied to the …

Public Attitudes And Knowledge Of The Black-Tailed Prairie Dog: A Common And Controversial Species, Donna Lybecker, Berton Lee Lamb, Phadrea Ponds

United States Geological Survey: Staff Publications

Black-tailed prairie dogs (Cynomys ludovicianus; hereafter, prairie dogs) are native to the short-grass prairie region of North America from Mexico to Canada (figure 1).According to government documents (64 Federal Register 57 at 14426–14427), before the 19th century expansion of the United States, prairie dogs inhabited millions of acres of the Great Plains and lived in huge colonies west of the Missouri River. Settlement of the Great Plains and the transformation of vast areas from native grassland to tilled farmland forever changed the prairie ecosystem and prairie dog habitat.
Over the course of the last century, the habitat range …

In Situ Observations On Three Species Of Large-Finned Deep-Sea Squids, M. Vecchione, C. F. E. Roper, Edith A. Widder, Tamara M. Frank

Marine & Environmental Sciences Faculty Articles

The manned submersible Johnson Sea-Link II was used for a series of dives on the continental slope of the eastern Gulf of Mexico in September 1995. The deep-sea squids Mastigoteuthis hjorti Chun, 1913 and Octopoteuthis megaptera (Verrill, 1885) were repeatedly observed at depths of 600–850 m. Both species were videotaped alive, in situ, for the first time during these dives. These species share the characteristic of very large fins, almost as long as the mantle length, but their swimming behavior observed in the vicinity of the submersible differed greatly. Throughout most of the videotaped sequences of O. megaptera, it …

Performance Study On Two Distance Vector Routing Protocols For Mobile Ad Hoc Networks, Yi Lu, Weichao Wang, Yuhui Zhong, Bharat Bhargava

Department of Computer Science Technical Reports

No abstract provided.

On A Use Of Golay Sequences For Asynchronous Ds Cdma Applications, Jennifer Seberry, Beata J. Wysocki, Tadeusz A. Wysocki

Faculty of Informatics - Papers (Archive)

Golay complementary sequences, often referred to as Golay pairs, are characterised by the property that the sum of their aperiodic autocorrelation functions equals to zero, except for the zero shift. Because of this property, Golay complementary sequences can be utilised to construct Hadamard matrices defining sets of orthogonal spreading sequences for DS CDMA systems of the lengths not necessary being a power of 2. In the paper, we present an evaluation, from the viewpoint of asynchronous DS CDMA applications, of some sets of spreading sequences derived from Golay complementary sequences. We then modify those sets of sequences to enhance their …

Groundwater Flow To A Horizontal Or Slanted Well In An Unconfined Aquifer, Hongbin Zhan, Vitaly A. Zlotnik

Department of Earth and Atmospheric Sciences: Faculty Publications

New semianalytical solutions for evaluation of the drawdown near horizontal and slanted wells with finite length screens in unconfined aquifers are presented. These fully three-dimensional solutions consider instantaneous drainage or delayed yield and aquifer anisotropy. As a basis, solution for the drawdown created by a point source in a uniform anisotropic unconfined aquifer is derived in Laplace domain. Using superposition, the point source solution is extended to the cases of the horizontal and slanted wells. The previous solutions for vertical wells can be described as a special case of the new solutions. Numerical Laplace inversion allows effective evaluation of the …

Characterization Of The Dust/Smoke Aerosol That Settled East Of The World Trade Center (Wtc) In Lower Manhattan After The Collapse Of The Wtc 11 September 2001, Paul J. Lioy, Clifford P. Weisel, Et Al, Robert C. Hale

VIMS Articles

The explosion and collapse of the World Trade Center (WTC) was a catastrophic event that produced an aerosol plume impacting many workers, residents, and commuters during the first few days after 11 September 2001. Three bulk samples of the total settled dust and smoke were collected at weather-protected locations east of the WTC on 16 and 17 September 200 1; these samples are representative of the generated material that settled immediately after the explosion and fire and the concurrent collapse of the two structures. We analyzed each sample, not differentiated by particle Size, for inorganic and organic composition. In the …

Creep And Creep-Recovery Models For Wood Under High Stress Levels, Zhiyong Cai, Kenneth J. Fridley, Michael O. Hunt, David V. Rosowsky

Civil and Environmental Engineering and Construction Faculty Research

Forty small clear southern pine specimens were loaded under third-point bending to examine creep and creep-recovery behavior for wood under high stress levels. Stress levels of between 69% and 91% of the predicted static strength were applied for 23 h with 1 h allowed for recovery, and the resulting deflection vs. time behavior was studied. The experimental creep and creep-recovery behavior was modeled using modified power law functions. The results indicate that these functions provide the best fit to both primary and secondary experimental data. The empirical models can be used to simulate the viscoelastic behavior of wood under high …

Coincident Fragment Detection In Strong Field Photoionization And Dissociation Of H₂, Horst Rottke, Christoph Trump, M. Wittmann, Georg Korn, Wolfgang Sandner, Robert Moshammer, Alexander Dorn, Claus Dieter Schroter, Daniel Fischer, Jose R. Crespo Lopez-Urrutia, Paul B. Neumayer, J. Deipenwisch, C. Hohr, Bernold Feuerstein, Joachim Hermann Ullrich

Physics Faculty Research & Creative Works

An investigation of the correlated electronic and nuclear motion in fragmentation of H₂ in 4 x 10¹⁴ W/cm², fs laser pulses at 795 nm was presented using the electron-ion momentum spectroscopy. The channel selective electron energy distribution indicated assumption of a new H₂ ionization mechanism to interpret the differences found in the fragmentation channels. The results showed that the momentum distribution of H⁺ ions in the dissociation channels H(1s) + H⁺ + e^- and 2H⁺ + 2e^- was independent of the kinetic energy of photoelectrons.

A Problematic Set Of Two-Loop Self-Energy Corrections, Ulrich D. Jentschura, Jorg Evers, Christoph H. Keitel, Krzysztof Pachucki

Physics Faculty Research & Creative Works

We investigate a specific set of two-loop self-energy corrections involving squared decay rates and point out that their interpretation is highly problematic. The corrections cannot be interpreted as radiative energy shifts in the usual sense. Some of the problematic corrections find a natural interpretation as radiative nonresonant corrections to the natural line shape. They cannot uniquely be associated with one and only one atomic level. While the problematic corrections are rather tiny when expressed in units of frequency (a few hertz for hydrogenic P levels) and do not affect the reliability of quantum electrodynamics at the current level of experimental …

Warcraft Iii - Maps & Benchmark Problems, Nathan R. Sturtevant, Blizzard Corp.

Moving AI Lab: 2D Maps and Benchmark Problems

Maps extracted from Warcraft III from Blizzard Corp. for use and distribution as benchmark problems.

Contains 36 maps and benchmark problem sets, scaled to 512x512 and converted to a simple grid-based format.

Digital Libraries To Knowledge Portals: Towards A Global Knowledge Portal For Secondary Schools In Singapore, Yin-Leng Theng, Dion Hoe-Lian Goh, Chu Keong Lee, Ee Peng Lim, Zehua Liu

Research Collection School Of Computing and Information Systems

For digital libraries to remain relevant in the new millennium where the ability to manage knowledge is critical, this paper explores how digital libraries could strategically be evolved into knowledge portals to encapsulate knowledge creation, management, sharing and reusability, features evidently lacking in most conventional digital libraries. Two digital library scenarios of use in education are described and implemented as knowledge portals using G-Portal and the Greenstone software. We hope that the initial work carried out on these two portal-like DLs will eventually form part of a Global Knowledge Portal for Secondary Schools in Singapore. Keywords Digital libraries, information portals, …

G-Portal : A Map-Based Digital Library For Distributed Geospatial And Georeferenced Resources, Ee Peng Lim, Dion Hoe-Lian Goh

Research Collection School Of Computing and Information Systems

As the World Wide Web evolves into an immense information network, it is tempting to build new digital library services and expand existing digital library services to make use of web content. In this paper, we present the design and implementation of G-Portal, a web portal that aims to provide digital library services over geospatial and georeferenced content found on the World Wide Web. G-Portal adopts a map-based user interface to visualize and manipulate the distributed geospatial and georeferenced content. Annotation capabilities are supported, allowing users to contribute geospatial and georeferenced objects as well as their associated metadata. The other …

Monitoring The Prey-Field Of Marine Predators: Combining Digital Imaging With Datalogging Tags, Sascha Hooker, Ian L. Boyd, Mark Jessop, Oliver Cox, John Blackwell, Peter Boveng, John Bengston

United States Department of Commerce: Staff Publications

There is increasing interest in the diving behavior of marine mammals. However, identifying foraging among recorded dives often requires several assumptions. The simultaneous acquisition of images of the prey encountered, together with records of diving behavior will allow researchers to more fully investigate the nature of subsurface behavior. We tested a novel digital camera linked to a time-depth recorder on Antarctic fur seals (Arctocephalus gazella). During the austral summer 2000-2001, this system was deployed on six lactating female fur seals at Bird Island, South Georgia, each for a single foraging trip. The camera was triggered at depths greater …

Willamette River And Columbia River Waste Load Allocation Model, Chris Berger, Robert Leslie Annear, Scott A. Wells

Civil and Environmental Engineering Faculty Publications and Presentations

A hydrodynamic and water quality model of the Lower Willamette River was developed to evaluate management alternatives designed to improve water quality. The Lower Willamette River is located in Oregon and drains a watershed covering 11500 square miles consisting of forested, agricultural, and urban lands. Inflows include treated municipal wastes and industrial effluents along with non-point sources from agricultural, silvicultural and urbanized land. The model was designed to address temperature, dissolved oxygen, algae, pH and bacteria concerns. The Corps of Engineers two-dimensional, laterally averaged, hydrodynamic and water quality model CE-QUAL-W2, Version 3 was applied. CE-QUAL-W2 consists of directly coupled hydrodynamic …

Applying Xml/Xslt Technology: A Case Study, Krishnaprasad Thirunarayan

Kno.e.sis Publications

Typically, paper-based semi-structured documents are used to communicate technical requirements in the industry. One approach to improving the efficiency and flexibility of searching and manipulating these documents is to obtain them in electronic form, and then make explicit the technical content in a form amenable to pattern matching and symbol manipulation. This paper explores the role of XML Technology for these purposes: the use of XML language to make explicit the content of a document in a standard fashion, and the use of XSLT to manipulate the content and mediate between applications that need this content. In order to recognize …

Effect Of Time Of Temperature Observation And Estimation Of Daily Solar Radiation For The Northern Great Plains, Usa, Rezaul Mahmood, Kenneth Hubbard

School of Natural Resources: Faculty Publications

Daily incident solar radiation is an important input for numerous crop growth simulation models. However, lack of recorded solar radiation is a significant impediment for most crop–climate studies. The present study aimed to overcome the problem of sparse historical data of solar radiation over the northern Great Plains. The approach was to develop a physically based solar radiation model wherein estimates were possible with minimum input data. In addition, this study investigates impacts of time of observation bias on the model formulation. The proposed model (M-H) requires measured daily range of air temperature (maximum minus minimum) and estimated daily clear-sky …

Implementing Qos Management For Workflow Systems, Jorge Cardoso, Amit P. Sheth, Krzysztof J. Kochut

Kno.e.sis Publications

Workflow management systems (WfMSs) have been used to support various types of business processes. As organizations adopt new working models, such as e-commerce, new challenges arise for workflow systems. One such challenge is that of quality of service (QoS) management. QoS management includes mechanisms that specify, compute, monitor, and control the quality of service of the products or services to be delivered. A good management of QoS directly impacts the success of organizations participating in e-commerce activities by better fulfilling customer expectations and achieving customer satisfaction. In this paper we present an implementation of a comprehensive QoS model for workflows …

Electric-Field-Induced Relativistic Larmor-Frequency Reduction, P Krekora, Q Su, Rainer Grobe

Faculty publications – Physics

Using the numerical solution to the time-dependent Dirac equation we show that the effect of relativity on the usual Larmor period for an electron in a magnetic field can be enhanced drastically if a suitably scaled and aligned static electric field is added to the interaction. This electric field does not change the electron's speed but leads to an elliptical spin precession due to relativity. This spin precession is accompanied by a position-dependent spin distribution.

Geospatial Data Handling For Web-Based And Mobile Applications, James Carswell

Articles

One of the main bottlenecks for web-based GIS usability is in the transmission and handling of the vast amounts of geospatial data involved. The shear volume of raster, vector, attribute, and other data to be analysed, queried, transmitted and displayed over the WWW in real-time is prohibited by connection speeds. In this paper we introduce e-Spatial technology, a fully integrated open standard web-based solution to manage multiple spatial relationships directly in an Oracle Spatial database and to deploy in real-time spatially enabled (or standard) applications completely independent of data volume. Indeed, no application code is ever installed on the client …

Web-Based Spatial Information Management Systems, James Carswell

Conference papers

In this paper we discuss the innovative software solutions offered by e-SpatialTM technology for the deployment of web-based and mobile spatial information management systems. This technology has been developed within the Oracle 9i Database environment and allows users to build and deploy spatially enabled Internet applications on any Oracle supported hardware platform and on any device running a Java Virtual Machine (e.g., standard web browsers, PDAs and other mobile devices). The paper focuses on a Land Information Management System (LIMS) application developed for the Irish Department of Agriculture. The application utilises the e-SpatialTM Information Server to deliver a spatially enabled …

Structural And Geomorphological Evolution Of Huangshan (Yellow Mountain), Anhui Province, China, Pei-Hua Huang, Robert F. Diffendal Jr., Ming-Qing Yang

School of Natural Resources: Faculty Publications

Huangshan (Yellow Mountain) is an 1864-m granite massif situated at 30° 10′ N and 118° 11′ E, south of the lower reaches of the Yangtze River. The granite formed during the Early Cretaceous and was subsequently uplifted several times along faults. After the initial uplift, about 54 Ma, erosion proceeded to wear away the mountain for the next 30 Ma. By 24 Ma the Bright Summit Peneplain had formed. Renewed uplift in the Miocene along the same fault systems produced a mountain in the same place as the original one. This mountain was eroded to produce a second mature denudational …

Sensitivity Comparison Of Ladar Receivers Designed To Detect Glint Targets, Christopher D. Brewer, Bradley D. Duncan, Edward A. Watson

Electro-Optics and Photonics Faculty Publications

We present four receiver designs for a ladar system, based on an optical parametric amplifier, that is designed to collect returns from glint targets. After coupling the return energy into periodically poled lithium niobate, the target backscatter is detected with either an infrared camera or a CCD array. Assuming reasonable detector and system characteristics, the sensitivity of each design is then evaluated by setting the receiver SNR detection threshold equal to one and using the minimum transmitted energy as the figure of merit. Through numerical analysis, we show that an upconversion receiver followed by a visible CCD array offers the …

Non-Dipolar Electron Angular Distributions From Fixed-In-Space Molecules, Renaud Guillemin, Oliver Hemmers, Dennis W. Lindle, E. Shigemasa, K. Le Guen, D. Ceolin, C. Miron, N. Leclercq, P. Morin, Marc Simon, P. W. Langhoff

Environmental Studies Faculty Publications

The first indication of nondipole effects in the azimuthal dependence of photoelectron angular distributions emitted from fixed-in-space molecules is demonstrated in N₂. Comparison of the results with angular distributions observed for randomly oriented molecules and theoretical derivations for the nondipole correction first order in photon momentum suggests that higher orders will be needed to describe distributions measured in the molecular frame.

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 …