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Acquisition of building geometry in the simulation of energy performance (open access)

Acquisition of building geometry in the simulation of energy performance

Building geometry is essential to any simulation of building performance. This paper examines the importing of building geometry into simulation of energy performance from the users' point of view. It lists performance requirements for graphic user interfaces that input building geometry, and discusses the basic options in moving from two- to three-dimensional definition of geometry and the ways to import that geometry into energy simulation. The obvious answer lies in software interoperability. With the BLIS group of interoperable software one can interactively import building geometry from CAD into EnergyPlus and dramatically reduce the effort otherwise needed for manual input.The resulting savings may greatly increase the value obtained from simulation, the number of projects in which energy performance simulation is used, and expedite decision making in the design process.
Date: June 28, 2001
Creator: Bazjanac, Vladimir
System: The UNT Digital Library
Alpha particle response characterization of CdZnTe (open access)

Alpha particle response characterization of CdZnTe

The coplanar-grid as well as other electron-only detection techniques are effective in overcoming some of the material problems of CdZnTe and, consequently, have led to efficient gamma-ray detectors with good energy resolution while operating at room temperature. The performance of these detectors is limited by the degree of uniformity in both electron generation and transport. Despite recent progress in the growth of CdZnTe material, small variations in these properties remain a barrier to the widespread success of such detectors. Alpha-particle response characterization of CdZnTe crystals fabricated into simple planar detectors is an effective tool to accurately study electron generation and transport. We have used a finely collimated alpha source to produce two-dimensional maps of detector response. A clear correlation has been observed between the distribution of precipitates near the entrance contact on some crystals and their alpha-response maps. Further studies are ongoing to determine the mechanism for the observed response variations and the reason for the correlation. This paper presents the results of these studies and their relationship to coplanar-grid gamma-ray detector performance.
Date: June 28, 2001
Creator: Amman, Mark; Lee, Julie S. & Luke, Paul N.
System: The UNT Digital Library
Approximate Splitting for Ensembles of Trees using Histograms (open access)

Approximate Splitting for Ensembles of Trees using Histograms

Recent work in classification indicates that significant improvements in accuracy can be obtained by growing an ensemble of classifiers and having them vote for the most popular class. Implicit in many of these techniques is the concept of randomization that generates different classifiers. In this paper, they focus on ensembles of decision trees that are created using a randomized procedure based on histograms. Techniques, such as histograms, that discretize continuous variables, have long been used in classification to convert the data into a form suitable for processing and to reduce the compute time. The approach combines the ideas behind discretization through histograms and randomization in ensembles to create decision trees by randomly selecting a split point in an interval around the best bin boundary in the histogram. The experimental results with public domain data show that ensembles generated using this approach are competitive in accuracy and superior in computational cost to other ensembles techniques such as boosting and bagging.
Date: September 28, 2001
Creator: Kamath, C.; Cantú-Paz, E. & Littau, D.
System: The UNT Digital Library
Atomic scale heating in energetic plasma deposition (open access)

Atomic scale heating in energetic plasma deposition

Energetic deposition using filtered cathodic arc plasma is known to lead to well adherent and dense films. Interface mixing, subplantation depth, texture, and stress of the growing film are often studied as a function of the kinetic energy of condensing ions. Ions have also potential energy contributing to atomic scale heating, secondary electron emission and potential sputtering, thereby affecting all film properties. A table is presented showing kinetic and potential energies of ions in cathodic arc plasmas. These energies are greater than the binding energy, surface binding energy, and activation energy of surface diffusion. The role of potential energy on film growth is not limited to the cathodic arc plasma deposition process.
Date: September 28, 2001
Creator: Anders, Andre
System: The UNT Digital Library
Benchmarking and tuning the MILC code on clusters and supercomputers (open access)

Benchmarking and tuning the MILC code on clusters and supercomputers

Recently, we have benchmarked and tuned the MILC code on a number of architectures including Intel Itanium and Pentium IV (PIV), dual-CPU Athlon, and the latest Compaq Alpha nodes. Results will be presented for many of these, and we shall discuss some simple code changes that can result in a very dramatic speedup of the KS conjugate gradient on processors with more advanced memory systems such as PIV, IBM SP and Alpha.
Date: December 28, 2001
Creator: Gottlieb, Steven A.
System: The UNT Digital Library
Case A Binary Evolution (open access)

Case A Binary Evolution

We undertake a comparison of observed Algol-type binaries with a library of computed Case A binary evolution tracks. The library consists of 5500 binary tracks with various values of initial primary mass M{sub 10}, mass ratio q{sub 0}, and period P{sub 0}, designed to sample the phase-space of Case A binaries in the range -0.10 {le} log M{sub 10} {le} 1.7. Each binary is evolved using a standard code with the assumption that both total mass and orbital angular momentum are conserved. This code follows the evolution of both stars until the point where contact or reverse mass transfer occurs. The resulting binary tracks show a rich variety of behavior which we sort into several subclasses of Case A and Case B. We present the results of this classification, the final mass ratio and the fraction of time spent in Roche Lobe overflow for each binary system. The conservative assumption under which we created this library is expected to hold for a broad range of binaries, where both components have spectra in the range G0 to B1 and luminosity class III - V. We gather a list of relatively well-determined observed hot Algol-type binaries meeting this criterion, as well as …
Date: March 28, 2001
Creator: Nelson, C A & Eggleton, P P
System: The UNT Digital Library
Charm lifetimes and mixing (open access)

Charm lifetimes and mixing

A review of the latest results on charm lifetimes and D-mixing is presented. The e{sup +}e{sup -} collider experiments are now able to measure charm lifetimes quite precisely, however comparisons with the latest results from fixed-target experiments show that possible systematic effects could be evident. The new D-mixing results from the B-factories have changed the picture that is emerging. Although the new world averaged value of y{sub CP} is now consistent with zero, there is still a very interesting and favored scenario if the strong phase difference between the Doubly-Cabibbo-suppressed and the Cabibbo-flavored D{sup 0} {yields} K{pi} decay is large.
Date: November 28, 2001
Creator: Cheung, Harry W.K.
System: The UNT Digital Library
Computational design and performance of the fast ocean atmosphere model, version one. (open access)

Computational design and performance of the fast ocean atmosphere model, version one.

The Fast Ocean Atmosphere Model (FOAM) is a climate system model intended for application to climate science questions that require long simulations. FOAM is a distributed-memory parallel climate model consisting of parallel general circulation models of the atmosphere and ocean with complete physics parameterizations as well as sea-ice, land surface, and river transport models. FOAM's coupling strategy was chosen for high throughput (simulated years per day). A new coupler was written for FOAM and some modifications were required of the component models. Performance data for FOAM on the IBM SP3 and SGI Origin2000 demonstrates that it can simulate over thirty years per day on modest numbers of processors.
Date: March 28, 2001
Creator: Jacob, R.; Schafer, C.; Foster, I.; Tobis, M. & Anderson, J.
System: The UNT Digital Library
Cost of dynamical quark simulations with improved staggered quarks (open access)

Cost of dynamical quark simulations with improved staggered quarks

The cost of dynamical quark simulations with improved staggered quarks is estimated based on current and planned running by the MILC collaboration. I find that a few 10s of Tera op years should be sufficient to calculate down to a lattice spacing of 0.045 fm.
Date: December 28, 2001
Creator: Gottlieb, Steven A
System: The UNT Digital Library
The Effect of Roll Waves on the Hydrodynamics of Falling Films Observed in Vertical Column Absorbers (open access)

The Effect of Roll Waves on the Hydrodynamics of Falling Films Observed in Vertical Column Absorbers

A thin falling film is well suited to simultaneous heat and mass transfer because of the small thermal resistance through the film and because of the large contact surface achievable at low flow rates. The film enters as a smooth laminar flow and quickly transitions into small-amplitude wavy flow. The waves grown in length and amplitude and are identified as roll waves. This flow regime is termed wavy-laminar flow, and modern heat and mass transfer equipment operate in this complicated transition regime. Research published in open literature has shown the mass flow rate in the rollwaves to be about 10 to 20 times greater than that in the laminar substrate. As the film fully develops, the waves grow in mass and the film substrate thins because fluid is swept from the substrate by the secondary flows of the roll wave. Many studies have been conducted to measure and correlate the film thickness of wavy-laminar flows. Literature data show that Nusselt's theory for smooth laminar flow can over predict the film thickness by as much as 20% for certain wavy-laminar flow conditions. The hydrodynamics of falling films were therefore studied to measure the film thickness of a free-surface falling film and …
Date: June 28, 2001
Creator: Miller, W.A.
System: The UNT Digital Library
Electromagnetic Imaging of C02 Sequestration at an Enhanced Oil Recovery Site (open access)

Electromagnetic Imaging of C02 Sequestration at an Enhanced Oil Recovery Site

Lawrence Livermore National Laboratory (LLNL) is currently involved in a long term study using time-lapse multiple frequency electromagnetic (EM) characterization at a waterflood enhanced oil recovery (EOR) site in California operated by Chevron Heavy Oil Division in Lost Hills, California. The petroleum industry's interest and the successful imaging results from this project suggest that this technique be extended to monitor CO{sub 2} sequestration at an EOR site also operated by Chevron. The impetus for this study is to develop the ability to image subsurface injected CO{sub 2} during EOR processes while simultaneously discriminating between pre-existing petroleum and water deposits. The goals of this study are to combine laboratory and field methods to image a pilot CO{sub 2} sequestration EOR site using the cross-borehole EM technique, improve the inversion process in CO{sub 2} studies by coupling results with petrophysical laboratory measurements, and focus on new gas interpretation techniques. In this study we primarily focus on how joint field and laboratory results can provide information on subsurface CO{sub 2} detection, CO{sub 2} migration tracking, and displacement of petroleum and water over time. This study directly addresses national energy issues in two ways: (1) the development of field and laboratory techniques to improve …
Date: February 28, 2001
Creator: Kirkendall, B. & Roberts, J.
System: The UNT Digital Library
Electromagnetic Imaging of CO2 Sequestration at an Enhanced Oil Recovery Site (open access)

Electromagnetic Imaging of CO2 Sequestration at an Enhanced Oil Recovery Site

Lawrence Livermore National Laboratory (LLNL) is currently involved in a long term study using time-lapse multiple frequency electromagnetic (EM) characterization at a waterflood enhanced oil recovery (EOR) site in California operated by Chevron Heavy Oil Division in Lost Hills, California (Figure 1). The petroleum industry's interest and the successful imaging results from this project suggest that this technique be extended to monitor CO{sub 2} sequestration at an EOR site also operated by Chevron. The impetus for this study is to develop the ability to image subsurface injected CO{sub 2} during EOR processes while simultaneously discriminating between pre-existing petroleum and water deposits. The goals of this study are to combine laboratory and field methods to image a pilot CO{sub 2} sequestration EOR site using the cross-borehole EM technique, improve the inversion process in CO{sub 2} studies by coupling results with petrophysical laboratory measurements, and focus on new gas interpretation techniques. In this study we primarily focus on how joint field and laboratory results can provide information on subsurface CO{sub 2} detection, CO{sub 2} migration tracking, and displacement of petroleum and water over time. This study directly addresses national energy issues in two ways: (1) the development of field and laboratory techniques …
Date: February 28, 2001
Creator: Kirkendall, B. & Roberts, J.
System: The UNT Digital Library
Femtosecond x-ray detectors via optical gating (open access)

Femtosecond x-ray detectors via optical gating

None
Date: June 28, 2001
Creator: Glover, T.E.
System: The UNT Digital Library
Further development of low noise MEVVA ion source (open access)

Further development of low noise MEVVA ion source

Based on the idea of a space-charge-limited mode of operation, the influence of a pair of electrostatic meshes on the beam parameters of the LBNL MEVVA-5 ion source was investigated. The meshes were placed in the expansion zone of the vacuum arc plasma. Apart from reducing the level of beam current fluctuations, this mode of operation provides significant control over the ion charge state distribution of the extracted beam. These effects can be understood taking not only space charge but also the high-directed ion drift velocities into account that are the same for different ion charge states of a material. The results of simulations of the processes involved are in good agreement with the experimental results.
Date: August 28, 2001
Creator: Oks, Efim; Yushkov, George; Litovko, Irina; Anders, Andre & Brown, Ian
System: The UNT Digital Library
General Relativistic Simulations of Stellar Core Collapse and Postbounce Evolution with Boltzmann Neutrino Transport (open access)

General Relativistic Simulations of Stellar Core Collapse and Postbounce Evolution with Boltzmann Neutrino Transport

We present self-consistent general relativistic simulations of stellar core collapse, bounce, and postbounce evolution for 13, 15, and 20 solar mass progenitors in spherical symmetry. Our simulations implement three-flavor Boltzmann neutrino transport and standard nuclear physics. The results are compared to our corresponding simulations with Newtonian hydrodynamics and O(v/c) Boltzmann transport.
Date: February 28, 2001
Creator: Liebendoerfer, M.
System: The UNT Digital Library
Hydrodynamic Modeling of a Multi-Pulse X-Ray Converter Target for DARHT - II (open access)

Hydrodynamic Modeling of a Multi-Pulse X-Ray Converter Target for DARHT - II

In phase two of the Dual-Axis Radiographic Hydrodynamic Test facility (DARHT-II), four electron beam pulses of variable pulse length strike an X-ray converter target to produce time-resolved X-ray image. An important requirement for the converter target is to minimize the hydrodynamic expansion of the converter material so that there is enough material to generate the required X-ray dose for all four pulses. Minimizing the hydrodynamic expansion is also important from the standpoint of beam transport. If there is too much expansion of the converter material, the spot-size of the beam will deteriorate due to the charge neutralization of the beam by the target plasma. The beam spot size can also be deteriorated by backstreaming ions. However, this effect can be minimized by placing a barrier foil in front of the target. In this paper, we present a converter target design, based on the simulations using the radiation hydrodynamics code LASNEX and the Monte Carlo radiation transport code MCNP, that can produce the required X-ray dose for all four pulses with tolerable X-ray spot size variation. Our calculations also show that the barrier foil may block the backstreaming ions for all four pulses.
Date: June 28, 2001
Creator: Ho, D. D. M.; Chen, Y. J.; Harte, J. & Young, D.
System: The UNT Digital Library
ICOOL: A TOOL FOR MUON COLLIDER SIMULATIONS. (open access)

ICOOL: A TOOL FOR MUON COLLIDER SIMULATIONS.

Current ideas for designing neutrino factories [ 1,2] and muon colliders [3] require unique configurations of fields and materials to prepare the muon beam for acceleration. This so-called front end system must accomplish the goals of phase rotation, bunching and cooling. We have continued the development of a 3-D tracking code, ICOOL [4], for examining possible muon collider front end configurations. A system is described in terms of a series of longitudinal regions with associated material and field properties. The tracking takes place in a coordinate system that follows a reference orbit through the system. The code takes into account decays and interactions of {approx}50-500 MeV/c muons in matter. Material geometry regions include cylinders and wedges. A number of analytic models are provided for describing the field configurations. Simple diagnostics are built into the code, including calculation of emittances and correlations, longitudinal traces, histograms and scatter plots. A number of auxiliary codes can be used for pre-processing, post-processing and optimization.
Date: September 28, 2001
Creator: FERNOW,R.C.
System: The UNT Digital Library
Improving the Methods Used to Evaluate Voluntary Energy-Efficiency Programs (open access)

Improving the Methods Used to Evaluate Voluntary Energy-Efficiency Programs

Despite progress that has been made in recent years, further improvements are needed in the methodologies commonly used to evaluate the energy savings arising from voluntary energy-efficiency programs. These voluntary programs are characterized by the fact that they do not involve mandatory codes or standards but instead use information and incentives to further the adoption of energy-efficient technologies and practices. Voluntary programs frequently are aimed at long-term transformation of markets that make lasting changes in consumer patterns of energy use. To date, many of the evaluations of such programs have focused on the direct effects to program participants and have not addressed the associated market transformation to the extent possible. Using information gathered through an extensive methodological review, the authors describe useful approaches taken in previous evaluations and draw conclusions concerning the best methods available for forecasting and measuring the impacts of voluntary programs.
Date: June 28, 2001
Creator: Schweitzer, M.
System: The UNT Digital Library
In celebration of the fixed target program with the Tevatron (open access)

In celebration of the fixed target program with the Tevatron

The Tevatron is the world's first large superconducting accelerator. With its construction, we gained the dual opportunities to advance the state of the art in accelerator technology with the machine itself and in particle physics with the experiments that became possible in a higher energy regime. There have been 43 experiments in the Tevatron fixed target program. Many of these are better described as experimental programs, each with a broad range of physics goals and results, and more than 100 collaborating physicists and engineers. The results of this program are three-fold: (1) new technologies in accelerators, beams and detectors which advanced the state of the art; (2) new experimental results published in the refereed physics journals; and (3) newly trained scientists who are both the next generation of particle physicists and an important part of the scientific, technical and educational backbone of the country as a whole. In this book they compile these results. There are sections from each experiment including what their physics goals and results were, what papers were published, and which students have received degrees. Summaries of these results from the program as a whole are quite interesting, but the physics results from this program are too …
Date: December 28, 2001
Creator: al., Jeffrey A. Appel et
System: The UNT Digital Library
LLNL Calibration Program: Data Collection, Ground Truth Validation, and Regional Coda Magnitude (open access)

LLNL Calibration Program: Data Collection, Ground Truth Validation, and Regional Coda Magnitude

Lawrence Livermore National Laboratory (LLNL) integrates and collects data for use in calibration of seismic detection, location, and identification. Calibration data is collected by (1) numerous seismic field efforts, many conducted under NNSA (ROA) and DTRA (PRDA) contracts, and (2) permanent seismic stations that are operated by national and international organizations. Local-network operators and international organizations (e.g. International Seismic Center) provide location and other source characterization (collectively referred to as source parameters) to LLNL, or LLNL determines these parameters from raw data. For each seismic event, LLNL rigorously characterizes the uncertainty of source parameters. This validation process is used to identify events whose source parameters are accurate enough for use in calibration. LLNL has developed criteria for determining the accuracy of seismic locations and methods to characterize the covariance of calibration datasets. Although the most desirable calibration events are chemical and nuclear explosions with highly accurate locations and origin times, catalogues of naturally occurring earthquakes offer needed geographic coverage that is not provided by man made sources. The issue in using seismically determined locations for calibration is validating the location accuracy. Sweeney (1998) presented a 50/90 teleseismic, network-coverage criterion (50 defining phases and 90{sup o} maximum azimuthal gap) that generally …
Date: August 28, 2001
Creator: Myers, S C; Mayeda, K; Walter, C; Schultz, C; O'Boyle, J; Hofstetter, A et al.
System: The UNT Digital Library
Local properties at the boundaries of irradiated regions in LCMO CMR films. (open access)

Local properties at the boundaries of irradiated regions in LCMO CMR films.

None
Date: November 28, 2001
Creator: Vlasko-Vlasov, V. K.; Welp, U.; Miller, D. J.; Lin, Y. K. & Crabtree, G. W.
System: The UNT Digital Library
Measurement Methodology of the Fissile Mass Flow Monitor for the HEU Transparency Implementation Instrumentation in Russia (open access)

Measurement Methodology of the Fissile Mass Flow Monitor for the HEU Transparency Implementation Instrumentation in Russia

The highly enriched uranium (HEU) Transparency Agreement between the U.S. and Russian Federation (RF) requires implementation of transparency measures in the Russian facilities that are supplying product low enriched uranium (LEU) to the U.S. from down blended weapon-grade HEU material. To satisfy the agreement's non-proliferation objectives, the U.S. DOE is implementing the fissile mass flow monitor (FMFM) instrumentation developed by Oak Ridge National Laboratory. The FMFM provides unattended non-intrusive measurements of {sup 235}U mass flow of the uranium hexafluoride (UF{sub 6}) gas in the process lines of HEU, the LEU blend stock, and the resulting lower assay product LEU (P-LEU) that is used for U.S. reactors. The instrumentation continuously traces the HEU flow through the blending point to the product LEU, enabling the U.S. to verify HEU material down blending. The FMFM relies on producing delayed gamma rays emitted from fission fragments carried by the UF{sub 6} flow. A thermalized californium-252 ({sup 252}Cf)-neutron source placed in an annular sleeve filled with moderator material that surrounds the pipe is modulated by a neutron absorbent shutter to induce fission in UF{sub 6}. For this technique to be effectively applicable the average range of resulting fission fragments in the UF{sub 6} gas must …
Date: June 28, 2001
Creator: Uckan, T.
System: The UNT Digital Library
Monitoring Carbon Dioxide Sequestration Using Electrical Resistance Tomography (ERT): Sensitivity Studies (open access)

Monitoring Carbon Dioxide Sequestration Using Electrical Resistance Tomography (ERT): Sensitivity Studies

If geologic formations are used to sequester carbon dioxide (CO{sub 2}), monitoring the CO{sub 2} injection will be required to confirm the performance of the reservoir system, assess leaks and flow paths, and understand the geophysical and geochemical interactions between the CO{sub 2} and the geologic minerals and fluids. Electrical methods are well suited for monitoring processes involving fluids, as electrical properties are sensitive to the presence and nature of the formation fluids. High resolution tomographs of electrical properties are now possible using it 3D technique called electrical resistance tomography (ERT). Surveys are commonly conducted utilizing vertical arrays of point electrodes in a cross-well configuration. Recent field results obtained using steel well casings as electrodes are promising. When 3D ERT imaging can be performed using existing well casings as long electrodes, the need for additional drilling of observation wells is minimized. Using a model patterned after an oil field undergoing CO{sub 2} flood, forward and inverse simulations of ERT surveys have been run to test the sensitivity of the method to changes resulting from CO{sub 2} migration. Factors considered include resistivity contrast, anomaly proximity to electrodes, anomaly size and shape, measurement noise, and the electrode configuration used to perform the …
Date: February 28, 2001
Creator: Newmark, R. L.; Ramierz, A. L. & Daily, W. D.
System: The UNT Digital Library
On the large Nc expansion in quantum chromodynamics (open access)

On the large Nc expansion in quantum chromodynamics

The author discusses methods based on the large Nc expansion to study nonperturbative aspects of quantum chromodynamics, the theory of the strong force. The author applies these methods to the analysis of weak decay processes and the nonperturbative computation of the weak matrix elements needed for a complete evaluation of these decays in the Standard Model of elementary particle physics.
Date: December 28, 2001
Creator: Bardeen, William A.
System: The UNT Digital Library