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Design and testing of a control strategy for a large naturallyventilated office building (open access)

Design and testing of a control strategy for a large naturallyventilated office building

The design for the new Federal Building for San Franciscoincludes an office tower that is to be naturally ventilated. Each flooris designed to be cross-ventilated, through upper windows that arecontrolled by the building management system (BMS). Users have controlover lower windows, which can be as much as 50 percent of the totalopenable area. There are significant differences in the performance andthe control of the windward and leeward sides of the building, andseparate monitoring and control strategies are determined for each side.The performance and control of the building has been designed and testedusing a modified version of EnergyPlus. Results from studies withEnergyPlus and CFD are used in designing the control strategy. EnergyPluswas extended to model a simplified version of the airflow patterndetermined using CFD. Wind-driven cross-ventilation produces a main jetthrough the upper openings of the building, across the ceiling from thewindward to the leeward side. Below this jet, the occupied regions aresubject to a recirculating air flow. Results show that temperatureswithin the building are predicted to be satisfactory, provided a suitablecontrol strategy is implemented uses night cooling in periods of hotweather. The control strategy has 10 window opening modes. EnergyPlus wasextended to simulate the effects of these modes, and to assess …
Date: March 16, 2004
Creator: Carrilho da Graca, Guilherme; Linden, Paul F. & Haves, Philip
System: The UNT Digital Library
In-situ Diffraction Studies of Shock Compressed Single-Crystal Iron (open access)

In-situ Diffraction Studies of Shock Compressed Single-Crystal Iron

The technique of in-situ wide angle diffraction has been used to study materials such as Si and Cu. We have extended our studies of shocked single crystal materials to include Fe (001) that is shock compressed by direct laser irradiation using the OMEGA and Janus lasers. A series of experiments was conducted in Fe at pressures above the Hugoniot Elastic Limit. Transient x-ray was used to record the response of multiple lattice planes simultaneously. This technique of wide-angle diffraction provides information on the lattice response both parallel and oblique to the shock propagation direction. In these experiments, compressions of up to 14% in the (002) planes were observed. Details on the experiments and analysis of the dynamic lattice compression will be presented.
Date: July 16, 2004
Creator: Kalantar, D H; Colvin, J D; Eggert, J; Lorenzana, H; Stolken, J; Hawreliak, J et al.
System: The UNT Digital Library
Fs Laser Fabrication of Photonic Structures in Glass: the Role of Glass Composition (open access)

Fs Laser Fabrication of Photonic Structures in Glass: the Role of Glass Composition

The use of fs lasers to directly write photonic structures inside a glass has great potential as a fabrication method for three-dimensional all-optical integrated components. The ability to use this technique with different glass compositions--specifically tailored for a specific photonics application--is critical to its successful exploitation. Consequently, it is important to understand how glass composition effects waveguide fabrication with fs laser pulses and how different glasses are structurally modified after exposure to fs laser pulses. We have used confocal laser spectroscopy to monitor the changes in glass structure that are associated with waveguide fabrication. Using a low power continuous wave (cw) Ar laser as excitation source we have measured both Raman and fluorescence spectra of the modified regions. Raman spectroscopy provides us with information on the network structure, whereas fluorescence measurements reveal the presence of optically active point defects in the glass. In this paper we review our work on fs-laser fabrication and characterization of photonic structures in glass and discuss the effect of glass composition on processing parameters and structural modification.
Date: June 16, 2004
Creator: Krol, D M; Chan, J W; Huser, T R; Risbud, S H & Hayden, J S
System: The UNT Digital Library
Status of The General Atomics Low Speed Urban Maglev Technology Development Program (open access)

Status of The General Atomics Low Speed Urban Maglev Technology Development Program

This paper presents the status of General Atomics Urban Maglev Program. The development provides an innovative approach for low speed transportation suitable for very challenging urban environments. Permanent magnets arranged in a 'Halbach' array configuration produce a relatively stiff magnetic suspension operating with an air gap of 25 mm. The project has progressed from design and prototype hardware testing, to the construction of a 120-meter full-scale test track, located in San Diego, California. Dynamic testing of the levitation, propulsion and guidance systems is being performed.
Date: June 16, 2004
Creator: Gurol, S; Baldi, R; Bever, D & Post, R
System: The UNT Digital Library
The Astro-E2 XRS/EBIT Microcalorimeter XC-ray Spectrometer (open access)

The Astro-E2 XRS/EBIT Microcalorimeter XC-ray Spectrometer

The X-ray Spectrometer (XRS) instrument is a revolutionary non-dispersive spectrometer that will form the basis for the Astro-E2 observatory to be launched in 2005. We have recently installed a flight spare XRS microcalorimeter spectrometer at the EBIT-I and SuperEBIT facility at LLNL replacing the XRS from the earlier Astro-E mission and providing twice the resolving power. The XRS microcalorimeter is an x-ray detector that senses the heat deposited by the incident photon. It achieves a high energy resolution by operating at 0.06K and by carefully engineering the heat capacity and thermal conductance. The XRS/EBIT instrument has 32 pixels in a square geometry and achieves an energy resolution of 6 eV at 6 keV, with a bandpass from 0.1 to 12 keV (or more at higher operating temperature). The instrument allows detailed studies of the x-ray line emission of laboratory plasmas. The XRS/EBIT also provides an extensive calibration 'library' for the Astro-E2 observatory.
Date: April 16, 2004
Creator: Porter, F S; Brown, G V; Boyce, K R; Kelley, R L; Kilbourne, C A; Beiersdorfer, P et al.
System: The UNT Digital Library
Massive Data Pre-Processing with a Cluster Based Approach (open access)

Massive Data Pre-Processing with a Cluster Based Approach

Data coming from complex simulation models reach easily dimensions much greater than available computational resources. Visualization of such data still represents the most intuitive and effective tool for scientific inspection of simulated phenomena. To ease this process several techniques have been adopted mainly concerning the use of hierarchical multi-resolution representations. In this paper we present the implementation of a hierarchical indexing schema for multiresolution data tailored to overwork the computational power of distributed environments.
Date: December 16, 2004
Creator: Borgo, R.; Cignoni, P.; Pascucci, V. & Scopigno, R.
System: The UNT Digital Library
Software Quality Assurance for Nuclear Safety Systems (open access)

Software Quality Assurance for Nuclear Safety Systems

The US Department of Energy has undertaken an initiative to improve the quality of software used to design and operate their nuclear facilities across the United States. One aspect of this initiative is to revise or create new directives and guides associated with quality practices for the safety software in its nuclear facilities. Safety software includes the safety structures, systems, and components software and firmware, support software and design and analysis software used to ensure the safety of the facility. DOE nuclear facilities are unique when compared to commercial nuclear or other industrial activities in terms of the types and quantities of hazards that must be controlled to protect workers, public and the environment. Because of these differences, DOE must develop an approach to software quality assurance that ensures appropriate risk mitigation by developing a framework of requirements that accomplishes the following goals: {sm_bullet} Ensures the software processes developed to address nuclear safety in design, operation, construction and maintenance of its facilities are safe {sm_bullet} Considers the larger system that uses the software and its impacts {sm_bullet} Ensures that the software failures do not create unsafe conditions Software designers for nuclear systems and processes must reduce risks in software applications …
Date: May 16, 2004
Creator: Sparkman, D R & Lagdon, R
System: The UNT Digital Library
K-Alpha Emission Spectra From Non-Equilibrium Ionizing Plasmas (open access)

K-Alpha Emission Spectra From Non-Equilibrium Ionizing Plasmas

K{alpha} X-ray emission spectra from highly charged Fe ions have been theoretically predicted using a detailed and systematic spectral model. Account has been taken of the fundamental atomic radiative-emission processes associated with inner-shell electron collisional excitation and ionization, as well as dielectronic recombination. Particular emphasis has been directed at extreme non-equilibrium or transient-ionization conditions, which can occur in astrophysical and tokamak plasmas. Good agreement has been found in comparisons with spectral observations on the EBIT-II electron beam ion trap at the Lawrence Livermore National Laboratory. We have identified spectral features that can serve as diagnostics of the electron density, the line-formation mechanism, and the charge-state distribution.
Date: December 16, 2004
Creator: Jacobs, V L; Decaux, V & Beiersdorfer, P
System: The UNT Digital Library
Parallel Computation of the Topology of Level Sets (open access)

Parallel Computation of the Topology of Level Sets

This paper introduces two efficient algorithms that compute the Contour Tree of a 3D scalar field F and its augmented version with the Betti numbers of each isosurface. The Contour Tree is a fundamental data structure in scientific visualization that is used to preprocess the domain mesh to allow optimal computation of isosurfaces with minimal overhead storage. The Contour Tree can also be used to build user interfaces reporting the complete topological characterization of a scalar field, as shown in Figure 1. Data exploration time is reduced since the user understands the evolution of level set components with changing isovalue. The Augmented Contour Tree provides even more accurate information segmenting the range space of the scalar field in portion of invariant topology. The exploration time for a single isosurface is also improved since its genus is known in advance. Our first new algorithm augments any given Contour Tree with the Betti numbers of all possible corresponding isocontours in linear time with the size of the tree. Moreover we show how to extend the scheme introduced in [3] with the Betti number computation without increasing its complexity. Thus, we improve on the time complexity from our previous approach [10] from O(m …
Date: December 16, 2004
Creator: Pascucci, V & Cole-McLaughlin, K
System: The UNT Digital Library
Singlet Free Energies of a Static Quark-Antiquark Pair. (open access)

Singlet Free Energies of a Static Quark-Antiquark Pair.

We study the singlet part of the free energy of a static quark anti-quark (Q{bar Q}) pair at finite temperature. The model is three flavor QCD with degenerate quark masses using N{sub {tau}} = 4 and 6 lattices with Asqtad staggered fermion action. We look at thermodynamics of the system around phase transition and study its scaling with lattice spacing and quark masses.
Date: June 16, 2004
Creator: Petrov, Konstantin
System: The UNT Digital Library
Supersymmetric Froggatt-Nielsen Models with Baryon- and Lepton-Number Violation (open access)

Supersymmetric Froggatt-Nielsen Models with Baryon- and Lepton-Number Violation

We systematically investigate the embedding of U(1)_X Froggatt-Nielsen models in (four-dimensional) local supersymmetry. We restrict ourselves to models with a single flavon field. We do not impose a discrete symmetry by hand, e.g., R-parity, baryon-parity or lepton-parity. Thus we determine the order of magnitude of the baryon- and/or lepton violating coupling constants through the Froggatt-Nielsen mechanism. We then scrutinize whether the predicted coupling constants are in accord with weak or GUT scale constraints. Many models turn out to be incompatible.
Date: April 16, 2004
Creator: Dreiner, Herbi K. & Thormeier, Marc
System: The UNT Digital Library
Warped Supersymmetric Unification with Non-Unified Superparticle Spectrum (open access)

Warped Supersymmetric Unification with Non-Unified Superparticle Spectrum

We present a new supersymmetric extension of the standard model. The model is constructed in warped space, with a unified bulk symmetry broken by boundary conditions on both the Planck and TeV branes. In the supersymmetric limit, the massless spectrum contains exotic colored particles along with the particle content of the minimal supersymmetric standard model (MSSM). Nevertheless, the model still reproduces the MSSM prediction for gauge coupling unification and does not suffer from a proton decay problem. The exotic states acquire masses from supersymmetry breaking, making the model completely viable, but thereis still the possibility that these states will be detected at the LHC. The lightest of these states is most likely A_5^XY, the fifth component of the gauge field associated with the broken unified symmetry. Because supersymmetry is broken on the SU(5)-violating TeV brane, the gaugino masses generated at the TeV scale are completely independent of one another. We explore some of the unusual features that the superparticle spectrum might have as a consequence.
Date: March 16, 2004
Creator: Nomura, Yasunori; Tucker-Smith, David & Tweedie, Brock
System: The UNT Digital Library
Matter Unification in Warped Supersymmetric SO(10) (open access)

Matter Unification in Warped Supersymmetric SO(10)

We construct models of warped unification with a bulk SO(10) gauge symmetry and boundary conditions that preserve the SU(4)_C x SU(2)_L x SU(2)_R Pati-Salam gauge group (422). In the dual 4D description, these models are 422 gauge theories in which the apparent unification of gauge couplings in the minimal supersymmetric standard model is explained as a consequence of strong coupling in the ultraviolet. The weakness of the gauge couplings at low energies is ensured in this 4D picture by asymptotically non-free contributions from the conformal sector, which are universal due to an approximate SO(10) global symmetry. The 422 gauge symmetry is broken to the standard model group by a simple set of Higgs fields. An advantage of this setup relative to SU(5) models of warped unification is that matter is automatically required to fill out representations of 422, providing an elegant understanding of the quantum numbers of the standard-model quarks and leptons. The models also naturally incorporate the see-saw mechanism for neutrino masses and bottom-tau unification. Finally, they predict a rich spectrum of exotic particles near the TeV scale, including states with different quantum numbers than those that appear in SU(5) models.
Date: March 16, 2004
Creator: Nomura, Yasunori & Tucker-Smith, David
System: The UNT Digital Library
Electron-helium scattering in the S-wave model using exterior complex scaling (open access)

Electron-helium scattering in the S-wave model using exterior complex scaling

Electron-impact excitation and ionization of helium is studied in the S-wave model. The problem is treated in full dimensionality using a time-dependent formulation of the exterior complex scaling method that does not involve the solution of large linear systems of equations. We discuss the steps that must be taken to compute stable ionization amplitudes. We present total excitation, total ionization and single differential cross sections from the ground and n=2 excited states and compare our results with those obtained by others using a frozen-core model.
Date: June 16, 2004
Creator: Horner, Daniel A.; McCurdy, C. William & Rescigno, Thomas N.
System: The UNT Digital Library
New advances in three dimensional transient electromagnetic inversion (open access)

New advances in three dimensional transient electromagnetic inversion

Inversion of transient electromagnetic (TEM) data sets to image the subsurface three-dimensional (3-D) electrical conductivity and magnetic permeability properties can be done directly in the time domain. The technique, first introduced by Wang et al. (1994) for causal and diffusive electromagnetic fields and subsequently implemented by Zhdanov and Portniaguine (1997) in the framework of iterative migration, is based upon imaging methods originally developed for seismic wavefields (Claerbout, 1971; Tarantola, 1984). In this paper we advance the original derivations of Wang et al. (1994) and Zhdanov and Portniaguine (1997) to treat non-causal TEM fields, as well as correct a flaw in the theory for treatment of magnetic field data. Our 3D imaging scheme is based on a conjugate-gradient search for the minimum of an error functional involving EM measurements governed by Maxwell's equations without displacement currents. Treatment for magnetic field, voltage (time derivative of the magnetic field) and electric field data are given. The functional can be computed by propagating the data errors back into the model in reverse time along with a DC field, sourced by the integrated data errors over the measurement time range. By correlating these fields, including the time-integrated back-propagated fields, with the corresponding incident field and …
Date: June 16, 2004
Creator: Newman, Gregory A. & Commer, Michael
System: The UNT Digital Library
Evolution of the New Breed of TID; Not Just for Tamper Indication (open access)

Evolution of the New Breed of TID; Not Just for Tamper Indication

Although the application of passive tamper indicating device (TID) systems will always have their place in specific material storage applications, the implementation of an active seal system with remote interrogation/monitoring capabilities presents opportunities not previously achievable. This paper discusses the Savannah River Site (SRS) K-Area's progress over the past few years to successfully implement and operate a remote material monitoring system using an active seal platform. Active TID systems are evolving to allow true remote monitoring of seal state data as well as incorporating monitoring of other variables such as material condition, facility status and/or environmental surroundings. Since 1996, K-Area has been testing and evaluating various TID systems for site-wide use. From the origins of a joint effort between SRS/Sandia National Labs/Russian Federation in 1999 to demonstrate transparency with active monitoring systems to having the first International Atomic Energy Agency recognized dual containment/surveillance system using active seals in the United States, K-Area has been successful in implementing a system which using an internally authenticated active TID to provide remote material monitoring. The Sandia-developed T-1 Electronic Sensor Platform (ESP), the primary component of the ''dual surveillance'' system installed in K-Area, has received ''authorization for use'' by both DOE-SR and the IAEA. …
Date: July 16, 2004
Creator: KOENIG, RICHARD
System: The UNT Digital Library
Design and implementation of a vacuum compatible laser-basedsub-nm resolution absolute distance measurement gauge (open access)

Design and implementation of a vacuum compatible laser-basedsub-nm resolution absolute distance measurement gauge

We describe the design and implementation of a vacuum compatible laser-based absolute distance measurement gauge with sub-nm resolution. The present system is compatible with operation in the 10{sup -8} Torr range and with some minor modifications could be used in the 10{sup -9} Torr range. The system is based on glancing incidence reflection and dual segmented diode detection. The system has been implemented as a focus sensor for extreme ultraviolet interferometry and microlithography experiments at Lawrence Berkeley National Laboratory's Advanced Light Source synchrotron radiation facility and 1{sigma} operational measurement noise floor of 0.26 nm has been demonstrated.
Date: February 16, 2004
Creator: Naulleau, Patrick P.; Denham, Paul E. & Rekawa, Senajith
System: The UNT Digital Library
Enhanced vibrations at surfaces with back-bonds nearly parallel to the surface (open access)

Enhanced vibrations at surfaces with back-bonds nearly parallel to the surface

It has been discovered that several very different surfaces exhibit a common property: unusually large vibration amplitudes of the outermost atoms, well beyond the enhancement normally expected at typical clean surfaces. These special surfaces are: ice H2O(0001), alpha-Al2O3(0001), alpha-Ga(010) and Si(111)-(2x1). The root-mean-square vibration amplitudes in these surfaces are at least double the bulk values. The common cause that may explain these vibration amplitudes is that the surface atoms (or molecules in the case of ice) only have back-bonds that are nearly parallel to the surface. In this geometry, vibrations, especially perpendicular to the surface, involve primarily bond bending rather than bond stretching/compression: since bond bending is relatively soft, the corresponding vibration modes can have larger amplitudes. It is suggested that theory examine and confirm this cause of enhanced surface vibration amplitudes, and explore its implication for other phenomena such as adsorption and catalysis.
Date: March 16, 2004
Creator: Van Hove, M.A.
System: The UNT Digital Library
Performance Improvements of a Tritiated Water Recovery System (open access)

Performance Improvements of a Tritiated Water Recovery System

Tritium processing equipment is installed inside gloveboxes. Leaks of tritium, normal and accidental, are captured by a tritium stripping system using an oxidation-absorption process. Tritium is captured as tritiated water in zeolite beds and is recovered by desorption and reduction. The regenerated zeolite beds are reused. Reduction of the tritiated water is accomplished by a zeolite bed recovery system using hot magnesium beds. The system has been in operation for about 10 years and met original design requirements. Recent expansion of the facility requires a higher capacity of the system. Operation data are collected and analyzed. Ways to increase the system capacity are discussed.
Date: August 16, 2004
Creator: Heung, Leung K.; Hsu, R. H.; Rice, J. L. & McGee, T. S.
System: The UNT Digital Library
Deep Vs Profiling Along the Top of Yucca Mountain Using a Vibroseis Source and Surface Waves (open access)

Deep Vs Profiling Along the Top of Yucca Mountain Using a Vibroseis Source and Surface Waves

Yucca Mountain, Nevada, was approved as the site for development of the geologic repository for high-level radioactive waste and spent nuclear fuel in the United States. The U.S. Department of Energy has been conducting studies to characterize the site and assess its future performance as a geologic repository. As part of these studies, a program of deep seismic profiling, to depths of 200 m, was conducted along the top of Yucca Mountain to evaluate the shear-wave velocity (V{sub s}) structure of the repository block. The resulting V{sub s} data were used as input into the development of ground motions for the preclosure seismic design of the repository and for postclosure performance assessment. The noninvasive spectral-analysis-of-surface-waves (SASW) method was employed in the deep profiling. Field measurements involved the use of a modified Vibroseis as the seismic source. The modifications allowed the Vibroseis to be controlled by a signal analyzer so that slow frequency sweeps could be performed while simultaneous narrow-band filtering was performed on the receiver outputs. This process optimized input energy from the source and signal analysis of the receiver outputs. Six deep V{sub s} profiles and five intermediate-depth (about 100 m) profiles were performed along the top of Yucca …
Date: March 16, 2004
Creator: Stokoe, K.; Rosenblad, B.; Wong, I.; Bay, J.; Thomas, P. & Silva, W.
System: The UNT Digital Library
Local structure around Sn in CeCoIn{sub 5-x}Sn{sub x} (open access)

Local structure around Sn in CeCoIn{sub 5-x}Sn{sub x}

The local structure around Sn dopants in CeCoIn{sub 5-x}Sn{sub z} has been probed by extended x-ray absorption fine structure (EXAFS) technique. The fit results for both x = 0.12 and x = 0.18 clearly indicate the dopant Sn atoms predominantly occupying the planar In(1) site. These results are consistent with the quasi-two-dimensional electronic properties of CeCoIn{sub 5} and is discussed in relation to the observed bulk properties.
Date: June 16, 2004
Creator: Daniel, M.; Han, S.-W.; Booth, C.H.; Cornelius, A.L.; Bauer, E.D. & Sarrao, J.L.
System: The UNT Digital Library
Imaging detectors and electronics - A view of the future (open access)

Imaging detectors and electronics - A view of the future

Imaging sensors and readout electronics have made tremendous strides in the past two decades. The application of modern semiconductor fabrication techniques and the introduction of customized monolithic integrated circuits have made large scale imaging systems routine in high energy physics. This technology is now finding its way into other areas, such as space missions, synchrotron light sources, and medical imaging. I review current developments and discuss the promise and limits of new technologies. Several detector systems are described as examples of future trends. The discussion emphasizes semiconductor detector systems, but I also include recent developments for large-scale superconducting detector arrays.
Date: June 16, 2004
Creator: Spieler, Helmuth
System: The UNT Digital Library
YbiV from E. coli K12 is a HAD phosphatase (open access)

YbiV from E. coli K12 is a HAD phosphatase

The protein YbiV from Escherichia coli K12 MG1655 is a hypothetical protein with sequence homology to the haloacid dehalogenase (HAD) superfamily of proteins. Although numerous members of this family have been identified, the functions of few are known. Using the crystal structure, sequence analysis, and biochemical assays, we have characterized ybiV as a HAD phosphatase. The crystal structure of YbiV reveals a two domain protein, one with the characteristic HAD hydrolase fold, the other an inserted a/b fold. In an effort to understand the mechanism we also solved and report the structures of YbiV in complex with beryllofluoride (BeF3-) and aluminum trifluoride (AlF3) which have been shown to mimic the phosphorylated intermediate and transition state for hydrolysis, respectively, in analogy to other HAD phosphatases. Analysis of the structures reveals the substrate binding cavity, which is hydrophilic in nature. Both structure and sequence homology indicate ybiV may be a sugar phosphatase, which is supported by biochemical assays which measured the release of free phosphate on a number of sugar-like substrates. We also investigated available genomic and functional data in an effort to determine the physiological substrate.
Date: March 16, 2004
Creator: Roberts, Anne; Lee, Seok-Yong; McCullagh, Emma; Silversmith, Ruth E. & Wemmer, David E.
System: The UNT Digital Library
Harmonic cascade FEL designs for LUX (open access)

Harmonic cascade FEL designs for LUX

LUX is a design concept for an ultrafast X-ray science facility, based on an electron beam accelerated to GeV energies in are circulating linac. Included in the design are short duration (200 fs or shorter FWHM) light sources using multiple stages of higher harmonic generation, seeded by a 200-250 nm laser of similar duration. This laser modulates the energy of a group of electrons within the electron bunch; this section of the electron bunch then produces radiation at a higher harmonic after entering a second, differently tuned undulator. Repeated stages in a cascade yield increasing photon energies up to 1 keV. Most of the undulators in the cascade operate in the low-gain FEL regime. Harmonic cascades have been designed for each pass of the recirculating linac up to a final electron beam energy of 3.1 GeV. For a given cascade, the photon energy can be selected over a wide range by varying the seed laser frequency and the field strength in the undulators. We present simulation results using the codes GENESIS and GINGER, as well as the results of analytical models which predict FEL performance. We discuss lattice considerations pertinent for harmonic cascade FELs, as well as sensitivity studies and …
Date: July 16, 2004
Creator: Penn, G.; Reinsch, M.; Wurtele, J.; Corlett, J. N.; Fawley, W. M.; Zholents, A. et al.
System: The UNT Digital Library