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2004 Rock Deformation Gordon Conference - August 8-12, 2004 (open access)

2004 Rock Deformation Gordon Conference - August 8-12, 2004

Rock Deformation Gordon Conference Agenda and Final Report.
Date: August 8, 2004
Creator: Kronenberg, A. K.
System: The UNT Digital Library
5th Biotechnological Investigations Ocean Margins Program (open access)

5th Biotechnological Investigations Ocean Margins Program

BI-OMP supports DOE's mission in Climate Change Research. The program provides the fundamental understanding of the linkages between carbon and nitrogen cycles in ocean margins. Researchers are providing a mechanistic understanding of these cycles, using the tools of modern molecular biology. The models that will allow policy makers to determine safe levels of greenhouse gases for the Earth System.
Date: January 8, 2004
Creator: Massol, Arturo & Buxeda, Rosa
System: The UNT Digital Library
Amplifying Real Estate Value through Energy&WaterManagement: From ESCO to 'Energy Services Partner' (open access)

Amplifying Real Estate Value through Energy&WaterManagement: From ESCO to 'Energy Services Partner'

The energy service company (ESCO) business model could become significantly more effective by integrating the energy-efficiency purveyor and their capital into the underlying building ownership and operation partnership, rather than the current model in which the ESCO remains an outsider with higher transaction costs and limited interest and participation in the value created by the cost savings. Resource conservation advocates rarely use the language of real estate to articulate the cost effectiveness of capital improvements aimed at reducing utility costs in commercial and residential income properties. Conventional methods that rely on rarefied academic notions of simple payback time or a narrow definition of return on investment fail to capture a significant component of the true market value created by virtue of reduced operating expenses. Improvements in energy and water efficiency can increase the fundamental profitability of real estate investments by raising Net Operating Income (NOI), and hence returns during the holding period, and, ultimately, proceeds at time of sale. We introduce the concept of an Energy Services Partner, who takes an equity interest in a real estate partnership in exchange for providing the expertise and capital required to reduce utility operating costs. Profit to all partners increases considerably as a …
Date: June 8, 2004
Creator: Mills, Evan
System: The UNT Digital Library
Analysis of copper-rich precipitates in silicon: chemical state,gettering, and impact on multicrystalline silicon solar cellmaterial (open access)

Analysis of copper-rich precipitates in silicon: chemical state,gettering, and impact on multicrystalline silicon solar cellmaterial

In this study, synchrotron-based x-ray absorption microspectroscopy (mu-XAS) is applied to identifying the chemical states of copper-rich clusters within a variety of silicon materials, including as-grown cast multicrystalline silicon solar cell material with high oxygen concentration and other silicon materials with varying degrees of oxygen concentration and copper contamination pathways. In all samples, copper silicide (Cu3Si) is the only phase of copper identified. It is noted from thermodynamic considerations that unlike certain metal species, copper tends to form a silicide and not an oxidized compound because of the strong silicon-oxygen bonding energy; consequently the likelihood of encountering an oxidized copper particle in silicon is small, in agreement with experimental data. In light of these results, the effectiveness of aluminum gettering for the removal of copper from bulk silicon is quantified via x-ray fluorescence microscopy (mu-XRF),and a segregation coefficient is determined from experimental data to beat least (1-2)'103. Additionally, mu-XAS data directly demonstrates that the segregation mechanism of Cu in Al is the higher solubility of Cu in the liquid phase. In light of these results, possible limitations for the complete removal of Cu from bulk mc-Si are discussed.
Date: November 8, 2004
Creator: Buonassisi, Tonio; Marcus, Matthew A.; Istratov, Andrei A.; Heuer, Matthias; Ciszek, Theodore F.; Lai, Barry et al.
System: The UNT Digital Library
Analysis of TPV Network Losses (a Presentation) (open access)

Analysis of TPV Network Losses (a Presentation)

This talk focuses on the theoretical analysis of electrical losses associated with electrically networking large numbers of TPV cells to produce high power TPV power generators.
Date: December 8, 2004
Creator: DePoy, DM; Dashiell, MW; Rahner, DD; Danielson, LR; Oppenlander, JE; Vell, JL et al.
System: The UNT Digital Library
Antenna-coupled bolometer arrays using transition-edgesensors (open access)

Antenna-coupled bolometer arrays using transition-edgesensors

We describe the development of an antenna-coupled bolometer array for use in a Cosmic Microwave Background polarization experiment. Prototype single pixels using double-slot dipole antennas and integrated microstrip band defining filters have been built and tested. Preliminary results of optical testing and simulations are presented. A bolometer array design based on this pixel will also be shown and future plans for application of the technology will be discussed.
Date: June 8, 2004
Creator: Myers, Michael J.; Ade, Peter; Engargiola, Greg; Holzapfel,William; Lee,Adrian T.; O'Brient, Roger et al.
System: The UNT Digital Library
Aspects of the Tribology of the Plastic Bonded Explosive LX-04 (open access)

Aspects of the Tribology of the Plastic Bonded Explosive LX-04

The coefficient of friction, {mu}, of the plastic bonded explosive (PBX) LX-04 was measured on stainless steel, aluminum, Teflon and the explosive itself as a function of temperature between ambient and 135 C at a rotational speed of 0.0025 rad/sec{sup -1}. An optical profilometer was used to analyze the mean surface roughness, R{sub a}, of the various materials. LX-04 is a composite of the explosive 1,3,5,7-tetranitroazacyclooctane (HMX) and Viton A in an 85/15 weight ratio. The average roughness of the pressed explosive surface was R{sub a} = 0.55 {micro}m. The coefficient of friction for LX-04 on stainless steel of R{sub a} = 0.40 {micro}m decreased from 0.38 at ambient to 0.18 at 95 C. Above this temperature {mu} was nearly constant to about 125 C, where the coefficient began to increase again. The opposite behavior was observed with aluminum with R{sub a} = 0.31 {micro}m. The coefficient of friction increased from about 0.3 at ambient to 0.46 at 125 C. At this temperature or above, {mu} tended to increase during the measurement, indicating that the sample may have been sticking to the counter surface. The coefficient of friction against Teflon of R{sub a} = 0.054 {micro}m was nearly constant from …
Date: July 8, 2004
Creator: Hoffman, D. M. & Chandler, J. B.
System: The UNT Digital Library
Aspects of the Tribology of the Plastic Bonded Explosive (PBX) 9404 (open access)

Aspects of the Tribology of the Plastic Bonded Explosive (PBX) 9404

The coefficient of friction, {mu}, of the plastic bonded explosive (PBX) 9404 was measured on stainless steel, aluminum, Teflon and the explosive itself as a function of temperature between ambient and 135 C at a rotational speed of 0.0025 rad/sec{sup -1}. An optical profilometer was used to analyze the mean surface roughness, R{sub a}, of the various materials. PBX 9404 is a composite of the explosive 1,3,5,7-tetranitroazacyclooctane (HMX) chloroethyl phosphate (CEF) and nitrocellulose in an 96/3/3 weight ratio. The average roughness of the pressed explosive surface was R{sub a} = 1.37 {micro}m. The coefficient of friction for PBX 9404 on stainless steel of R{sub a} = 0.40 {micro}m increased from 0.22 at ambient to 0.34 at 95 C. Above this temperature {mu} decreased to about 0.23 at 125 C. Similar behavior was observed with aluminum with R{sub a} = 0.31 {micro}m. The coefficient of friction increased from about 0.08 at ambient to 0.48 at 115 C. Above this temperature, {mu} tended to decrease slightly. The coefficient of friction against Teflon of R{sub a} = 0.054 {micro}m was sigmoidal, increasing from about 0.3 at ambient to about at 0.49 {+-} 0.002 above 115 C. Against a PBX 9404 counter surface, the …
Date: July 8, 2004
Creator: Hoffman, D. M. & Chandler, J. B.
System: The UNT Digital Library
Checkpointing Shared Memory Programs at the Application-level (open access)

Checkpointing Shared Memory Programs at the Application-level

Trends in high-performance computing are making it necessary for long-running applications to tolerate hardware faults. The most commonly used approach is checkpoint and restart(CPR)-the state of the computation is saved periodically on disk, and when a failure occurs, the computation is restarted from the last saved state. At present, it is the responsibility of the programmer to instrument applications for CPR. Our group is investigating the use of compiler technology to instrument codes to make them self-checkpointing and self-restarting, thereby providing an automatic solution to the problem of making long-running scientific applications resilient to hardware faults. Our previous work focused on message-passing programs. In this paper, we describe such a system for shared-memory programs running on symmetric multiprocessors. The system has two components: (i)a pre-compiler for source-to-source modification of applications, and (ii) a runtime system that implements a protocol for coordinating CPR among the threads of the parallel application. For the sake of concreteness, we focus on a non-trivial subset of OpenMP that includes barriers and locks. One of the advantages of this approach is that the ability to tolerate faults becomes embedded within the application itself, so applications become self-checkpointing and self-restarting on any platform. We demonstrate this by …
Date: September 8, 2004
Creator: Bronevetsky, Greg; Schulz, Martin; Szwed, Peter; Marques, Daniel & Pingali, Keshav
System: The UNT Digital Library
Clocking Femtosecond X-Rays (open access)

Clocking Femtosecond X-Rays

The Sub-Picosecond Pulse Source (SPPS) at the Stanford Linear Accelerator Center (SLAC) produces the brightest ultrafast x-ray pulses in the world, and is the first to employ compressed femtosecond electron bunches for the x-ray source. Both SPPS and future X-ray Free Electron Lasers (XFEL's) will use precise measurements of individual electron bunches to time the arrival of x-ray pulses for time-resolved experiments. At SPPS we use electro-optic sampling (EOS) to perform these measurements. Here we present the first results using this method. An ultrafast laser pulse (135 fs) passes through an electro-optic crystal adjacent to the electron beam. The refractive index of the crystal is distorted by the strong electromagnetic fields of the ultra-relativistic electrons, and this transient birefringence is imprinted on the laser polarization. A polarizer decodes this signal, producing a time-dependent image of the compressed electron bunch. Our measurements yield the relative timing between an ultrafast optical laser and an ultrafast x-ray pulse to within 60 fs, making it possible to use the SPPS to observe atomic-scale ultrafast dynamics initiated by laser-matter interaction.
Date: October 8, 2004
Creator: Cavalieri, A. L.; Fritz, D. M.; Lee, S. H.; Bucksbaum, P. H.; Reis, D. A.; Mills, D. M. et al.
System: The UNT Digital Library
Comments on Shimony's 'An Analysis of Stapp's 'A bell-type theoremwithout hidden variables'' (open access)

Comments on Shimony's 'An Analysis of Stapp's 'A bell-type theoremwithout hidden variables''

The hidden-variable theorems of Bell and followers depend upon an assumption, namely the hidden-variable assumption, that conflicts with the precepts of quantum philosophy. Hence from an orthodox quantum perspective those theorems entail no faster-than-light transfer of information. They merely reinforce the ban on hidden variables. The need for some sort of faster-than-light information transfer can be shown by using counterfactuals instead of hidden variables. Shimony's criticism of that argument fails to take into account the distinction between no-faster-than-light connection in one direction and that same condition in both directions. The argument can be cleanly formulated within the framework of a fixed past, open future interpretation of quantum theory, which neatly accommodates the critical assumptions that the experimenters are free to choose which experiments they will perform. The assumptions are compatible with the Tomonaga-Schwinger formulation of quantum field theory, and hence with orthodox quantum precepts, and with the relativistic requirement that no prediction pertaining to an outcome in one region can depend upon a free choice made in a region spacelike-separated from the first.
Date: September 8, 2004
Creator: Stapp, Henry P.
System: The UNT Digital Library
A Comparison of Inexact Newton and Coordinate Descent Meshoptimization Technqiues (open access)

A Comparison of Inexact Newton and Coordinate Descent Meshoptimization Technqiues

We compare inexact Newton and coordinate descent methods for optimizing the quality of a mesh by repositioning the vertices, where quality is measured by the harmonic mean of the mean-ratio metric. The effects of problem size, element size heterogeneity, and various vertex displacement schemes on the performance of these algorithms are assessed for a series of tetrahedral meshes.
Date: July 8, 2004
Creator: Diachin, L F; Knupp, P; Munson, T & Shontz, S
System: The UNT Digital Library
Creep of Nearly Lamellar TiAl Alloy Containing W (open access)

Creep of Nearly Lamellar TiAl Alloy Containing W

Effects of W on the creep resistance of two nearly fully lamellar TiAl alloys with 1.0 and 2.0 at.%W have been investigated. In the low stress regime (LS) a nearly quadratic (1.5<n<2) creep behavior was observed. It is found that the addition of W can improve the creep resistance; however, the addition of excess W can result in the formation of {beta} phase, which produces an adverse effect on the creep strength.
Date: April 8, 2004
Creator: Hodge, A M; Hsiung, L M & Nieh, T
System: The UNT Digital Library
Defects in p-GaN and their atomic structure (open access)

Defects in p-GaN and their atomic structure

In this paper defects formed in p-doped GaN:Mg grown with Ga polarity will be discussed. The atomic structure of these characteristic defects (Mg-rich hexagonal pyramids and truncated pyramids) in bulk and thin GaN:Mg films grown with Ga polarity was determined at atomic resolution by direct reconstruction of the scattered electron wave in a transmission electron microscope. Small cavities were present inside the defects. The inside walls of the cavities were covered by GaN which grew with reverse polarity compared to the matrix. It was proposed that lateral overgrowth of the cavities restores matrix polarity on the defect base. Exchange of Ga and N sublattices within the defect compared to the matrix lead to a 0.6 {+-} 0.2 {angstrom} displacement between the Ga sublattices of these two areas. A [1{und 1}00]/3 shift with change from AB stacking in the matrix to BC within the entire pyramid is observed
Date: October 8, 2004
Creator: Liliental-Weber, Z.; Tomaszewicz, T.; Zakharov, D.; Jasinski, J. & and O'Keefe, M.
System: The UNT Digital Library
Development of a Quantitative Approach to Incorporating Stakeholder Values into Total Maximum Daily Loads: Dominguez Channel Case Study (open access)

Development of a Quantitative Approach to Incorporating Stakeholder Values into Total Maximum Daily Loads: Dominguez Channel Case Study

The federal Clean Water Act (CWA) Section 303(d)(1)(A) requires each state to conduct a biennial assessment of its waters, and identify those waters that are not achieving water quality standards. The result of this assessment is called the 303(d) list. The CWA also requires states to establish a priority ranking for waters on the 303(d) list of impaired waters and to develop and implement Total Maximum Daily Loads (TMDLs) for these waters. Over 30,000 segments of waterways have been listed as impaired by the Environmental Protection Agency (EPA). The EPA has requested local communities to submit plans to reduce discharges by specified dates or have them developed by the EPA. An investigation of this process found that plans to reduce discharges were being developed based on a wide range of site investigation methods. The Department of Energy requested Lawrence Livermore National Laboratory to develop appropriate tools to assist in improving the TMDL process. The EPA has shown support and encouragement of this effort. Our investigation found that improving the stakeholder input process would facilitate many of the TMDL processes, given the resources available to the interested and responsible parties. The first model that we have developed is a stakeholder allocation …
Date: June 8, 2004
Creator: Stewart, J.
System: The UNT Digital Library
Development of a Real-Time Radiological Area Monitoring Network for Emergency Response at Lawrence Livermore National Laboratory (open access)

Development of a Real-Time Radiological Area Monitoring Network for Emergency Response at Lawrence Livermore National Laboratory

A real-time radiological sensor network for emergency response was developed and deployed at the Lawrence Livermore National Laboratory (LLNL). The Real-Time Radiological Area Monitoring (RTRAM) network is comprised of 16 Geiger-Mueller (GM) sensors positioned on the LLNL Livermore site perimeter to continuously monitor for a radiological condition resulting from a terrorist threat to site security and the health and safety of LLNL personnel. The RTRAM network sensor locations coincide with wind sector directions to provide thorough coverage of the one square mile site. These low-power sensors are supported by a central command center (CCC) and transmit measurement data back to the CCC computer through the LLNL telecommunications infrastructure. Alarm conditions are identified by comparing current data to predetermined threshold parameters and are validated by comparison with plausible dispersion modeling scenarios and prevailing meteorological conditions. Emergency response personnel are notified of alarm conditions by automatic radio and computer based notifications. A secure intranet provides emergency response personnel with current condition assessment data that enable them to direct field response efforts remotely. The RTRAM network has proven to be a reliable system since initial deployment in August 2001 and maintains stability during inclement weather conditions.
Date: March 8, 2004
Creator: Bertoldo, N; Hunter, S; Fertig, R; Laguna, G & MacQueen, D
System: The UNT Digital Library
Effect of Aging on the Toughness of Human Cortical Bone: Evaluation by R-Curves (open access)

Effect of Aging on the Toughness of Human Cortical Bone: Evaluation by R-Curves

Age-related deterioration of the fracture properties of bone, coupled with increased life expectancy, are responsible for increasing incidence of bone fracture in the elderly, and hence, an understanding of how its fracture properties degrade with age is essential. The present study describes ex vivo fracture experiments to quantitatively assess the effect of aging on the fracture toughness properties of human cortical bone in the longitudinal direction. Because cortical bone exhibits rising crack-growth resistance with crack extension, unlike most previous studies the toughness is evaluated in terms of resistance-curve (R-curve) behavior, measured for bone taken from wide range of age groups (34-99 years). Using this approach, both the ex vivo crack-initiation and crack-growth toughness are determined and are found to deteriorate with age; the initiation toughness decreases some 40% over six decades from 40 to 100 years, while the growth toughness is effectively eliminated over the same age range. The reduction in crack-growth toughness is considered to be associated primarily with a degradation in the degree of extrinsic toughening, in particular involving crack bridging in the wake of the crack.
Date: October 8, 2004
Creator: Kinney, J
System: The UNT Digital Library
The Effect of Organic Ligand Binding on the Growth CdSe Nanoparticles Probed by Ab-Initio Calculations (open access)

The Effect of Organic Ligand Binding on the Growth CdSe Nanoparticles Probed by Ab-Initio Calculations

None
Date: October 8, 2004
Creator: Puzder, A.; Williamson, A. J.; Zaitseva, N.; Galli, G.; Manna, L. & Alivisatos, A. P.
System: The UNT Digital Library
Effect of the grain boundary on the evolution of deformation in a bicrystal (open access)

Effect of the grain boundary on the evolution of deformation in a bicrystal

The role of grain boundary constraint in strain localization and concomitant constitutive response was examined by performing a series of uniaxial compression tests on a tantalum bicrystal. Tantalum single crystals were diffusion bonded to form a (011) 90 twist boundary that was compressed along the common [011] direction. The plastic deformation resulted in the creation of deformation bands away from the highly constraining grain boundary, resembling those bands known from single crystal plastic deformation. Near the grain boundary, such deformation band formation could not be detected. Instead a distinctive pattern of crystal lattice rotation was observed that filled a rather large volume (several millimeters in size) around the bicrystal grain boundary. The internal deformation band structure as well as the crystal lattice rotation pattern near the bicrystal grain boundary were characterized and found to give greater rates of work hardening in the neighborhood of the grain boundary.
Date: September 8, 2004
Creator: Ziegler, Alexander; Campbell, Geoffrey H.; Kumar, Mukul & Stolken, James S.
System: The UNT Digital Library
Effects of backlight structure on absorption experiments (open access)

Effects of backlight structure on absorption experiments

The impact of spectral details in the backlight of absorption spectroscopy experiments is considered. It is shown that experimentally unresolved structure in the backlight spectrum can introduce significant errors in the inferred transmission. Furthermore, it is shown that a valuable experimental procedure previously used to test the accuracy of the data fails to reveal these errors.
Date: November 8, 2004
Creator: Iglesias, C A
System: The UNT Digital Library
An electron front end for the Fermilab multi-species 8 GeV SCRF linac (open access)

An electron front end for the Fermilab multi-species 8 GeV SCRF linac

Fermilab is considering a 8 GeV superconducting linac whose primary mission is to serve as an intense H{sup -} injector for the main injector. This accelerator is also planned to be used for accelerating various other species (e.g. electrons, protons and muons). In the present paper we investigate the possibility of such a linac to accelerate high-brightness electron beam up to {approx} 7 GeV. We propose a design for the electron front end based on a photoinjector and consider the electron beam dynamics along the linac. Start-to-end simulations of the full accelerator for electrons are presented. Finally the potential applications of such an electron beam are outlined.
Date: July 8, 2004
Creator: Piot, Philippe R.-G. & Foster, G W
System: The UNT Digital Library
Empirical analysis of the spot market implications ofprice-elastic demand (open access)

Empirical analysis of the spot market implications ofprice-elastic demand

Regardless of the form of restructuring, deregulated electricity industries share one common feature: the absence of any significant, rapid demand-side response to the wholesale (or, spotmarket) price. For a variety of reasons, electricity industries continue to charge most consumers an average cost based on regulated retail tariff from the era of vertical integration, even as the retailers themselves are forced to purchase electricity at volatile wholesale prices set in open markets. This results in considerable price risk for retailers, who are sometimes forbidden by regulators from signing hedging contracts. More importantly, because end-users do not perceive real-time (or even hourly or daily) fluctuations in the wholesale price of electricity, they have no incentive to adjust their consumption in response to price signals. Consequently, demand for electricity is highly inelastic, and electricity generation resources can be stretched to the point where system stability is threatened. This, then, facilitates many other problems associated with electricity markets, such as market power and price volatility. Indeed, economic theory suggests that even modestly price-responsive demand can remove the stress on generation resources and decrease spot prices. To test this theory, we use actual generator bid data from the New York control area to construct supply …
Date: July 8, 2004
Creator: Siddiqui, Afzal S.; Bartholomew, Emily S. & Marnay, Chris
System: The UNT Digital Library
Evidence for neutrino mass: A decade of discovery (open access)

Evidence for neutrino mass: A decade of discovery

Neutrino mass and mixing are amongst the major discoveries of recent years. From the observation of flavor change in solar and atmospheric neutrino experiments to the measurements of neutrino mixing with terrestrial neutrinos, recent experiments have provided consistent and compelling evidence for the mixing of massive neutrinos. The discoveries at Super-Kamiokande, SNO, and KamLAND have solved the long-standing solar neutrino problem and demand that we make the first significant revision of the Standard Model in decades. Searches for neutrinoless double-beta decay probe the particle nature of neutrinos and continue to place limits on the effective mass of the neutrino. Possible signs of neutrinoless double-beta decay will stimulate neutrino mass searches in the next decade and beyond. I review the recent discoveries in neutrino physics and the current evidence for massive neutrinos.
Date: December 8, 2004
Creator: Heeger, Karsten M.
System: The UNT Digital Library
Experimental study of 351-nm and 527-nm laser-initiated surface damage on fused silica surfaces due to typical contaminants (open access)

Experimental study of 351-nm and 527-nm laser-initiated surface damage on fused silica surfaces due to typical contaminants

Optics damage under high-intensity illumination may be the direct result of laser light interaction with a contaminant on the surface. Contaminants of interest are small particles of the materials of construction of large laser systems and include aluminum, various absorbing glasses, and fused silica. In addition, once a damage site occurs and begins to grow, the ejecta from the growing damage site create contamination on nearby optic surfaces and may initiate damage on these surfaces via a process we call ''fratricide.'' We report on a number of experiments that we have performed on fused silica optics that were deliberately contaminated with materials of interest. The experiments were done using 527-nm light as well as 351-nm light. We have found that many of the contaminant particles are removed by the interaction with the laser and the likelihood of removal and/or damage is a function of both fluence and contaminant size. We have developed an empirical model for damage initiation in the presence of contaminants.
Date: November 8, 2004
Creator: Honig, J.; Norton, M. A.; Hollingsworth, W. G.; Donohue, E. E. & Johnson, M. A.
System: The UNT Digital Library