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

Physical Sciences and Mathematics Commons

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

PDF

2002

Discipline
Institution
Keyword
Publication
Publication Type

Articles 511 - 540 of 3395

Full-Text Articles in Physical Sciences and Mathematics

On Porosity Prediction From Seismic Data In Ghawar Field, Saudi Arabia, Thomas M. Loretto Sep 2002

On Porosity Prediction From Seismic Data In Ghawar Field, Saudi Arabia, Thomas M. Loretto

Thomas M Loretto

No abstract provided.


Expressing Logistic Regression Coefficients As Changes In Initial Probability Values: Useful Information For Practitioners, John Fraas, J Michael Drushal, Jef Graham Sep 2002

Expressing Logistic Regression Coefficients As Changes In Initial Probability Values: Useful Information For Practitioners, John Fraas, J Michael Drushal, Jef Graham

John W. Fraas

No abstract provided.


The Analysis Of Placement Values For Evaluating Discriminatory Measures, Margaret S. Pepe, Tianxi Cai Sep 2002

The Analysis Of Placement Values For Evaluating Discriminatory Measures, Margaret S. Pepe, Tianxi Cai

UW Biostatistics Working Paper Series

The idea of using measurements such as biomarkers, clinical data, or molecular biology assays for classification and prediction is popular in modern medicine. The scientific evaluation of such measures includes assessing the accuracy with which they predict the outcome of interest. Receiver operating characteristic curves are commonly used for evaluating the accuracy of diagnostic tests. They can be applied more broadly, indeed to any problem involving classification to two states or populations (D = 0 or D = 1). We show that the ROC curve can be interpreted as a cumulative distribution function for the discriminatory measure Y in the …


Development Of A Systems Engineering Model Of The Chemical Separations Process, Yitung Chen, Randy Clarksean, Darrell Pepper Sep 2002

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

Separations Campaign (TRP)

The AAA program is developing technology for the transmutation of nuclear waste to address many of the long-term disposal issues. An integral part of this program is the proposed chemical separations scheme. This process, as envisioned by Argonne National Laboratory (ANL) researchers, will be outlined later in this report.

Nearly all issues related to risks to future generations arising from long-term disposal of such spent nuclear fuel is attributable to ~1% of its content. This 1% is made up primarily of plutonium, neptunium, americium, and curium (the transuranic elements) and long-lived isotopes of iodine and technetium created as products from …


Development Of A Mechanistic Understanding Of High-Temperature Deformation Of Alloy Ep-823 For Transmutation Applications: Annual Progress Report (September 2001 – August 2002), Ajit K. Roy, Brendan O'Toole Sep 2002

Development Of A Mechanistic Understanding Of High-Temperature Deformation Of Alloy Ep-823 For Transmutation Applications: Annual Progress Report (September 2001 – August 2002), Ajit K. Roy, Brendan O'Toole

Transmutation Sciences Materials (TRP)

The purpose of this project is to evaluate the elevated temperature tensile properties of Alloy EP-823, a leading target material for accelerator-driven waste transmutation applications. This alloy has been proven to be an excellent structural material to contain the lead-bismuth-eutectic (LBE) nuclear coolant needed for fast spectrum operations. Very little data exist in the open literature on the tensile properties of this alloy. The test material will be thermally treated prior to the evaluation of its tensile properties at temperatures relevant to the transmutation applications. The deformation characteristics of tensile specimens, upon completion of testing, will be evaluated by surface …


On-Site Sewage Disposal Systems & Septage Management For Individual Homes And Small Communities, James R. Hegarty Sep 2002

On-Site Sewage Disposal Systems & Septage Management For Individual Homes And Small Communities, James R. Hegarty

Watershed Management Plans and Reports

The purpose of this paper is two-fold:

To identify alternatives and/or improvements to conventional septic systems for residential sewage collection and treatment for small communities and residential developments.

To research existing ordinances that require on-going management of residential and community septic systems, disposal of septage, and develop a model septic system and septage management ordinance that can apply to Kent County communities.

It is hoped that this study’s recommendations will be adopted in Kent County. Eventually, Kent County’s model program can be used to effect statewide implementation of responsible environmental policies that will improve our environment and public health. The …


Calibrating A 4-Wheel Mobile Robot, Phillip J. Mckerrow, D. Ratner Sep 2002

Calibrating A 4-Wheel Mobile Robot, Phillip J. Mckerrow, D. Ratner

Faculty of Informatics - Papers (Archive)

When a mobile robot is constructed the odometry must be calibrated. Calibrating a 4-wheel robot requires the accurate measurement of steering angle as well as translation and rotation. Some measurements are made with a tape measure and some with ultrasonic sensors. The measurements are used to determine the parameters of the odometry calibration matrix and the steering kinematic model. A procedure for calibrating a 4-wheel robot is discussed.


Training Of The Exchange-Bias Effect In Nio-Fe Heterostructures, A. Hochstrat, Christian Binek, Wolfgang Kleemann Sep 2002

Training Of The Exchange-Bias Effect In Nio-Fe Heterostructures, A. Hochstrat, Christian Binek, Wolfgang Kleemann

Christian Binek Publications

The training effect of a NiO(001)/Fe(110) heterostructure is studied from magnetic hysteresis loops measured by superconducting quantum interference device magnetometry. Consecutive hysteresis loops exhibit a decreasing exchange bias effect. This behavior is known as the training effect, which reflects the dependence of the exchange bias field on the antiferromagnetic interface magnetization. In order to evidence this dependence, we study the decrease of the total saturation magnetization of the heterostructure for an increasing number of hysteresis cycles. Assuming proportionality between the interface magnetization and the total saturation magnetization, the description of the data is consistent within the phenomenological Meiklejohn Bean approach.


Coupling Of Coamps And Wavetech With Improved Wave Physics, Shahrdad Sajjadi, Pat Fitzpatrick, Gueorgui Mostovoi, Yongzuo Li, Matt Bettencourt Sep 2002

Coupling Of Coamps And Wavetech With Improved Wave Physics, Shahrdad Sajjadi, Pat Fitzpatrick, Gueorgui Mostovoi, Yongzuo Li, Matt Bettencourt

Publications

The Model Coupling Executable Library (MCEL), developed at the University of Southern Mississippi's Center of Higher Learning, has been successfully used to couple the Coupled Ocean/Atmospheric Mesoscale Prediction System (COAMPS) and the ocean wave model WAVEWATCH. An example of its application is shown for Hurricane Gordon, showing that two-way coupling results affects boundary layer physics differently than one-way coupling --- in this case, resulting in larger o z and, consequently, larger surface fluxes and a more intense hurricane. However, since analyzing MCEL is difficult because the wave physics is inaccurate, improvements to the wave algorithms are also part of the …


Late Quaternary Slip Rates Across The Central Tien Shan, Kyrgyzstan, Central Asia, Stephen C. Thompson, Ray J. Weldon, Charles M. Rubin, Kanatbek Abdrakhmatov, Peter Molnar, Glenn W. Berger Sep 2002

Late Quaternary Slip Rates Across The Central Tien Shan, Kyrgyzstan, Central Asia, Stephen C. Thompson, Ray J. Weldon, Charles M. Rubin, Kanatbek Abdrakhmatov, Peter Molnar, Glenn W. Berger

All Faculty Scholarship for the College of the Sciences

Slip rates across active faults and folds show that late Quaternary faulting is distributed across the central Tien Shan, not concentrated at its margins. Nearly every intermontane basin contains Neogene and Quaternary syntectonic strata deformed by Holocene north‐south shortening on thrust or reverse faults. In a region that spans two thirds of the north‐south width of the central Tien Shan, slip rates on eight faults in five basins range from ∼0.1 to ∼3 mm/yr. Fault slip rates are derived from faulted and folded river terraces and from trenches. Radiocarbon, optically stimulated luminescence, and thermoluminescence ages limit ages of terraces and …


Whole Mantle Shear Structure Beneath The East Pacific Rise, Timothy I. Melbourne, Donald V. Helmberger Sep 2002

Whole Mantle Shear Structure Beneath The East Pacific Rise, Timothy I. Melbourne, Donald V. Helmberger

All Faculty Scholarship for the College of the Sciences

We model broadband seismograms containing triplicated S, S2, and S3 along with ScS to produce a pure path one‐dimensional model extending from the crust to the core‐mantle boundary beneath the East Pacific Rise. We simultaneously model all body wave shapes and amplitudes, thereby eliminating depth‐velocity ambiguities. The data consist of western North American broadband recordings of East Pacific Rise (EPR) affiliate transform events that form a continuous record section out to 82° and sample nearly the entire East Pacific Rise. The best fitting synthetics contain attenuation and small changes in lithospheric thickness needed to correct for …


Using The Emulab Network Testbed To Evaluate The Armada I/O Framework For Computational Grids, Ron Oldfield, David Kotz Sep 2002

Using The Emulab Network Testbed To Evaluate The Armada I/O Framework For Computational Grids, Ron Oldfield, David Kotz

Computer Science Technical Reports

This short report describes our experiences using the Emulab network testbed at the University of Utah to test performance of the Armada framework for parallel I/O on computational grids.


Accelerated Hazards Model: Method, Theory And Applications, Ying Qing Chen, Nicholas P. Jewell, Jingrong Yang Sep 2002

Accelerated Hazards Model: Method, Theory And Applications, Ying Qing Chen, Nicholas P. Jewell, Jingrong Yang

U.C. Berkeley Division of Biostatistics Working Paper Series

In an accelerated hazards model, the hazard functions of a failure time are related through the time scale-change, which is often a function of covariates and associated parameters. When the hazard functions have special properties, such as monotonicity in time, the parameters may be clinically meaningful in measuring a treatment effect. This paper reviews methodological and theoretical development of this model. Applications of the accelerated hazards model including sample size calculation in clinical trials, are also explored.


Characterizing A Defect In A One-Dimensional Bar, Cynthia Gangi, Sameer Shah Sep 2002

Characterizing A Defect In A One-Dimensional Bar, Cynthia Gangi, Sameer Shah

Mathematical Sciences Technical Reports (MSTR)

We examine the inverse problem of locating and describing an internal point defect in a one­ dimensional rod W by controlling the heat inputs and measuring the subsequent temperatures at the boundary of W. We use a variation of the forward heat equation to model heat flow through W, then propose algorithms for locating an internal defect and quantifying the effect the defect has on the heat flow. We implement these algorithms, analyze the stability of the procedures, and provide several computational examples.


Caustics In Tachyon Matter And Other Born-Infeld Scalars, Gary Felder, Lev Kofman, Alexei Starobinsky Sep 2002

Caustics In Tachyon Matter And Other Born-Infeld Scalars, Gary Felder, Lev Kofman, Alexei Starobinsky

Physics: Faculty Publications

We consider scalar Born-Infeld type theories with arbitrary potentials V(T) of a scalar field T. We find that for models with runaway potentials V(T) the generic inhomogeneous solutions after a short transient stage can be very well approximated by the solutions of a Hamilton-Jacobi equation that describes free streaming wave front propagation. The analytic solution for this wave propagation shows the formation of caustics with multi-valued regions beyond them. We verified that these caustics appear in numerical solutions of the original scalar BI non-linear equations. Our results include the scalar BI model with …


Development And Implementation Of A Comprehensive Lake And Reservoir Strategy For Nebraska As A Model For Agricultural Dominated Ecosystems, John C. Holz, James W. Merchant, Anatoly A. Gitelson, Sherilyn C. Fritz, Kyle D. Hoagland, Istvan Bogardi, Donald C. Rundquist Sep 2002

Development And Implementation Of A Comprehensive Lake And Reservoir Strategy For Nebraska As A Model For Agricultural Dominated Ecosystems, John C. Holz, James W. Merchant, Anatoly A. Gitelson, Sherilyn C. Fritz, Kyle D. Hoagland, Istvan Bogardi, Donald C. Rundquist

Department of Earth and Atmospheric Sciences: Faculty Publications

In agriculturally dominated regions, land use practices have an unusually large impact on water bodies and, therefore, land use may reduce the utility of current ecoregion-based approaches to lake classification by dampening the signals that underlie the ecoregion framework. A team of water quality researchers has been assembled to develop a comprehensive classification scheme for agriculturally dominated ecosystems, using Nebraska as a highly representative model. Three objectives critical to achieving this goal are to establish: (1) a protocol for aggregating water bodies in agricultural ecosystems into classification strata and identifying reference conditions for these classes; (2) the role of remote …


Reconstruction Of Cracks With Unknown Transmission Condition From Boundary Data, F Ronald Ogborne Iii, Melissa E. Vellela Sep 2002

Reconstruction Of Cracks With Unknown Transmission Condition From Boundary Data, F Ronald Ogborne Iii, Melissa E. Vellela

Mathematical Sciences Technical Reports (MSTR)

We examine the problem of Identifying both the location and constitutive law governing electrical current flow across a one-dimensional linear crack in a two dimensional region when the crack only partially blocks the flow of current. We develop a a constructive numerical procedure for solving the inverse problem and provide computational examples.


Locally Efficient Estimation Of Regression Parameters Using Current Status Data, Chris Andrews, Mark J. Van Der Laan, James M. Robins Sep 2002

Locally Efficient Estimation Of Regression Parameters Using Current Status Data, Chris Andrews, Mark J. Van Der Laan, James M. Robins

U.C. Berkeley Division of Biostatistics Working Paper Series

In biostatistics applications interest often focuses on the estimation of the distribution of a time-variable T. If one only observes whether or not T exceeds an observed monitoring time C, then the data structure is called current status data, also known as interval censored data, case I. We consider this data structure extended to allow the presence of both time-independent covariates and time-dependent covariate processes that are observed until the monitoring time. We assume that the monitoring process satisfies coarsening at random.

Our goal is to estimate the regression parameter beta of the regression model T = Z*beta+epsilon where the …


Case-Control Current Status Data, Nicholas P. Jewell, Mark J. Van Der Laan Sep 2002

Case-Control Current Status Data, Nicholas P. Jewell, Mark J. Van Der Laan

U.C. Berkeley Division of Biostatistics Working Paper Series

Current status observation on survival times has recently been widely studied. An extreme form of interval censoring, this data structure refers to situations where the only available information on a survival random variable, T, is whether or not T exceeds a random independent monitoring time C, a binary random variable, Y. To date, nonparametric analyses of current status data have assumed the availability of i.i.d. random samples of the random variable (Y, C), or a similar random sample at each of a set of fixed monitoring times. In many situations, it is useful to consider a case-control sampling scheme. Here, …


Domain Wall Relaxation, Creep, Sliding, And Switching In Superferromagnetic Discontinuous Co80Fe20/Al2O3 Multilayers, X. Chen, O. Sichelschmidt, Wolfgang Kleemann, Christian Binek, J.B. Sousa, Susana Cardoso De Freitas, P.P. Freitas Sep 2002

Domain Wall Relaxation, Creep, Sliding, And Switching In Superferromagnetic Discontinuous Co80Fe20/Al2O3 Multilayers, X. Chen, O. Sichelschmidt, Wolfgang Kleemann, Christian Binek, J.B. Sousa, Susana Cardoso De Freitas, P.P. Freitas

Christian Binek Publications

The ac susceptibility of a superferromagnetic discontinuous multilayer [Co80Fe20(1.4   nm)/ Al2O3(3   nm)]10 is measured as a function of temperature, frequency, and field amplitude and compared to static and dynamic hysteresis loops. Its properties are successfully mapped onto the predicted [T. Nattermann, V. Pokrovsky, and V. M. Vinokur, Phys. Rev. Lett. 87, 197005 (2001).] dynamical phase transitions, which link the relaxation, creep, sliding, and switching regimes of pinned domain walls.


The Tide Is High For The Boston Beaches, Marissa Glowac Sep 2002

The Tide Is High For The Boston Beaches, Marissa Glowac

New England Journal of Public Policy

In 1993, Massachusetts Governor William Weld and Boston Mayor Thomas Menino approved the “Back to the Beaches” project, a seven-year, $30.5 million public project to restore nineteen Boston Harbor beaches. Today, these sites have new, cleaner sand, improved access, and new amenities and facilities now ready to offer additional opportunities for recreation. People are coming back to the Boston Harbor beaches in numbers significantly higher than a decade ago. This study concludes that the implementation and success of the “Back to the Beaches” project can be attributed to several factors — an increased public awareness of the value of open …


Development Of A Hybrid Photo-Diode And Its Front-End Electronics For The Btev Experiment, Raymond Mountain Sep 2002

Development Of A Hybrid Photo-Diode And Its Front-End Electronics For The Btev Experiment, Raymond Mountain

Physics - All Scholarship

This paper describes the development of a 163-channel Hybrid Photo-Diode (HPD) to be used in the RICH Detector for the BTEV Experiment. This is a joint development project with DEP, Netherlands. It also reports on the development of associated front-end readout electronics based on the va_btev ASIC, undertaken with IDEAS, Norway. Results from bench tests of the first prototypes are presented.


Experimental Observation Of Energetic Ions Accelerated By Three-Dimensional Magnetic Reconnection In A Laboratory Plasma, Michael R. Brown, C. D. Cothran, Matthew Joseph Landreman , '03, David J. Schlossberg , '01, W. H. Matthaeus Sep 2002

Experimental Observation Of Energetic Ions Accelerated By Three-Dimensional Magnetic Reconnection In A Laboratory Plasma, Michael R. Brown, C. D. Cothran, Matthew Joseph Landreman , '03, David J. Schlossberg , '01, W. H. Matthaeus

Physics & Astronomy Faculty Works

Magnetic reconnection is widely believed responsible for heating the solar corona as well as for generating X-rays and energetic particles in solar flares. On astrophysical scales, reconnection in the intergalactic plasma is a prime candidate for a local source (Mpc) of cosmic rays exceeding the Greisen-Zatsepin-Kuzmin cutoff (∼10(19) eV). In a laboratory astrophysics experiment, we have made the first observation of particles accelerated by magnetic reconnection events to energies significantly above both the thermal and the characteristic magnetohydrodynamic energies. These particles are correlated temporally and spatially with the formation of three-dimensional magnetic structures in the reconnection region.


Trends. War On Personality And Personality And War: Comments On Nass And Lee (2002), Ibpp Editor Sep 2002

Trends. War On Personality And Personality And War: Comments On Nass And Lee (2002), Ibpp Editor

International Bulletin of Political Psychology

This Trends article discusses another article – Identity and deconstruction, by Clifford Nass and Kwan Min Yee – published in volume 3 (2002) of Archives of Psychiatry & Psychotherapy in which the authors demonstrate that people reliably attribute personality characteristics to computer-synthesized speech, exploring the ramifications in a political psychological context.


Field Trip Guide (For The Nebraska Well Drillers Association) Central Nebraska Geology, James W. Goeke, Robert F. Diffendal Jr., Duane A. Eversoll Sep 2002

Field Trip Guide (For The Nebraska Well Drillers Association) Central Nebraska Geology, James W. Goeke, Robert F. Diffendal Jr., Duane A. Eversoll

Conservation and Survey Division

Field trip guide, for the Nebraska Well Drillers Association, covering Central Nebraska Geology from September 2002.


The Tegrid Semantic Web Application, Steven Gollery, Jens G. Pohl Sep 2002

The Tegrid Semantic Web Application, Steven Gollery, Jens G. Pohl

Collaborative Agent Design (CAD) Research Center

Over the past several years there has been an increasing recognition of the shortcomings of message-passing data-processing systems that compute data without understanding, and the vastly superior potential capabilities of information-centric systems that incorporate an internal information model with sufficient context to support a useful level of automatic reasoning.

The key difference between a data-processing and an information-centric environment is the ability to embed in the information-centric software some understanding of the information being processed. The term information-centric refers to the representation of information in the computer, not to the way it is actually stored in a digital machine. This …


Proceedings Of The 2002 Onr Decision-Support Workshop Series: Transformation..., Collaborative Agent Design Research Center Sep 2002

Proceedings Of The 2002 Onr Decision-Support Workshop Series: Transformation..., Collaborative Agent Design Research Center

Collaborative Agent Design (CAD) Research Center

In August of 1998 the Collaborative Agent Design Research Center (CADRC) of the California Polytechnic State University in San Luis Obispo (Cal Poly), approached Dr. Phillip Abraham of the Office of Naval Research (ONR) with the proposal for an annual workshop focusing on emerging concepts in decision-support systems for military applications. The proposal was considered timely by the ONR Logistics Program Office for at least two reasons. First, rapid advances in information systems technology over the past decade had produced distributed, collaborative computer-assistance capabilities with profound potential for providing meaningful support to military decision makers. Indeed, some systems based on …


The Role Of Discovery In Context-Building Decision-Support Systems, Steven J. Gollery, Jens G. Pohl Sep 2002

The Role Of Discovery In Context-Building Decision-Support Systems, Steven J. Gollery, Jens G. Pohl

Collaborative Agent Design (CAD) Research Center

There are many sources of on-line information available to those responsible for making decisions in complex situations. However, most of that information is either intended for human use or is available only in custom or proprietary formats. Both of these conditions reduce the ability of computer software to perform automatic reasoning about this information. As a result, the usefulness of on-line information in intelligent decision-support systems is currently limited to the few sources that are implemented specifically for those systems. The vast mass of sources that do not fit that description are virtually invisible.

Current practices for integrating multiple information …


Data, Information, And Knowledge In The Context Of Sils, Michael A. Zang, Jens G. Pohl Sep 2002

Data, Information, And Knowledge In The Context Of Sils, Michael A. Zang, Jens G. Pohl

Collaborative Agent Design (CAD) Research Center

Data, information, and knowledge are becoming increasingly common terms in the literature of the software industry. This terminology originated some time ago in the disciplines of cognitive science and artificial intelligence to reference three closely related but distinct concepts. Traditionally, mainstream software engineering has lumped all three concepts together as data and has only recently begun to distinguish between them. Unfortunately, the popular desire to distinguish between data, information, and knowledge within the mainstream has blurred the individual meanings of the words to the point where there is no longer a clear-cut distinction between them for most people. This problem …


Monte Carlo Simulation On The Indirect Exchange Interactions Of Co-Doped Zno Film, Abraham F. Jalbout, Hanning Chen, Scott L. Whittenburg Sep 2002

Monte Carlo Simulation On The Indirect Exchange Interactions Of Co-Doped Zno Film, Abraham F. Jalbout, Hanning Chen, Scott L. Whittenburg

Chemistry and Biochemistry Faculty Publications

Monte Carlo simulations using a three-dimensional lattice model studied the Ruderman–Kittel–Kasuya–Yosida (RKKY) indirect exchange interaction of doped magnetic Co ions in ZnOfilms. The results of the calculations show that the RKKY interaction in Co-doped ZnO is long ranged and its magnitude is proportional to (inverse of the distance from a central ion). The sign oscillates with a frequency that depends on the concentration of the carrier. The long-distance sum of the RKKY indirect exchange energies is positive indicating that these materials are ferromagnetic, in direct correlation with previously reported results.