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Memory Effects in Fractional Brownian Motion with Hurst Exponent H<1/3 (open access)

Memory Effects in Fractional Brownian Motion with Hurst Exponent H<1/3

This article discusses a study on the regression to the origin of a walker driven by dynamically generated fractional Brownian motion.
Date: August 27, 2010
Creator: Bologna, Mauro; Vanni, Fabio; Krokhin, Arkadii A. & Grigolini, Paolo
System: The UNT Digital Library
Electronic and Transport Properties of Artificial Gold Chains (open access)

Electronic and Transport Properties of Artificial Gold Chains

Article on electronic and transport properties of artificial gold chains.
Date: August 27, 2004
Creator: Calzolari, Arrigo; Cavazzoni, Carlo & Buongiorno Nardelli, Marco
System: The UNT Digital Library
["Bush takes middle-ground approach on gay issues" article, August 27, 2003] (open access)

["Bush takes middle-ground approach on gay issues" article, August 27, 2003]

An article, written by Ron Hutcheson for the Lesbian/Gay Rights Lobby of Texas, about Charles Francis' influence with President George W. Bush. It also covers Bush's policies and stance on several gay issues.
Date: August 27, 2003
Creator: Hutcheson, Ron
System: The UNT Digital Library
First-principles calculation of atomic structure and electrochemical potential of Li{sub 1+x}V{sub 3}O{sub 8}. (open access)

First-principles calculation of atomic structure and electrochemical potential of Li{sub 1+x}V{sub 3}O{sub 8}.

Interest in the {gamma}-bronze, Li{sub 1+x}V{sub 3}O{sub g}, as a possible electrode material in rechargeable Li batteries has stimulated several experimental studies on this system. Detailed interpretation of the electrochemical and physical-property measurements is complicated by uncertainties regarding the structural arrangement of Li atoms as a function of x and by a phase transition between two monoclinic structures ({gamma}{sub a}, {gamma}{sub b}) during intercalation. To elucidate the atomic structures and the phase transition, first-principles calculations are performed with the local-density-functional-theory (LDFT) planewave pseudopotential method for both {gamma}{sub a} and {gamma}{sub b}, as a function of lithiation. Calculations for the compositions 1 + x = 1.5 and 1 + x = 4 confirm that the Li configuration determined in the existing x-ray diffraction structure refinements (at 1 + x = 1.2 and 1 + x = 4 respectively), coincide with the predicted low-energy configurations. Structure predictions were made at intermediate compositions, for which no experimental structure measurement is available. The order in which the tetrahedrally coordinated Li sites are filled at equilibrium as a function of x in {gamma}{sub a}, was predicted. Calculated electrochemical potentials as a function of composition agree well with experimental data.
Date: August 27, 1998
Creator: Benedek, R.
System: The UNT Digital Library
Mechanical and electrical properties of ZnO/Ag nanocomposites. (open access)

Mechanical and electrical properties of ZnO/Ag nanocomposites.

Effects of Ag particle dispersions on microstructural development and some properties were investigated for ZnO/Ag nanocomposites. They were fabricated by Pulse Electric Current Sintering (PECS) Process to achieve finer and densified microstructure. ZnO/Ag nanocomposites with novel microstructure which were prepared by a reduction process using Ag{sub 2}O fine powders were compared with microcomposites prepared by mixing of Ag and ZnO powders. SEM observation indicated that fine Ag particles were homogeneously dispersed within the ZnO matrix grains and at the grain boundaries for ZnO/Ag nanocomposites prepared by the reduction process using Ag{sub 2}O fine powder. Hardness and fracture toughness increased with increasing the Ag volume fraction. Linear resistivity was decreased with increasing Ag volume fraction. However, the mechanical and electrical properties appeared to the significantly different for composites prepared by two different powder processes.
Date: August 27, 1998
Creator: Hayashi, Y.
System: The UNT Digital Library
Laser-generated metallic hydrogen (open access)

Laser-generated metallic hydrogen

Hydrogen reaches the minimum conductivity of a metal at 140 GPa (1.4 Mbar) and 3000 K. These conditions were achieved using a two-stage light-gas gun. The authors have investigated computationally the use of a laser-heated hohlraum to shock compress hydrogen to these conditions in samples sufficiently thin that the metallic fluid might be quenched metastably on release of dynamic pressure. A configuration was found such that the duration of maximum pressure is sufficiently long that the hydrogen film cools by thermal conduction before pressure is released.
Date: August 27, 1999
Creator: Nellis, W J & Pollaine, S M
System: The UNT Digital Library
Lawrence Livermore National Laboratory hot spot mobile laboratory (open access)

Lawrence Livermore National Laboratory hot spot mobile laboratory

Gross alpha/beta/tritium liquid The Hot Spot Mobile Laboratory is an asset used to analyze samples (some high hazard) from the field. Field laboratories allow the quick turnaround of samples needed to establish weapon condition and hazard assessment for the protection of responders and the public. The Hot Spot Lab is configured to fly anywhere in the world and is staffed by expert scientists and technicians from Lawrence Livermore National Laboratory who perform similar functions in their routine jobs. The Hot Spot Team carries sample control kits to provide responding field teams with the procedures, tools, and equipment for sample collection and field measurements. High-hazard samples brought back from the field are prepared for analysis in HEPA-filtered gloveboxes staffed by technicians from LLNL's Plutonium Facility. The samples are passed on to the Mobile Laboratory which carries a variety of radiological and chemical analytical equipment in portable configuration for use in the field. Equipment and personnel can also deploy special assets to local hospitals or the field for detection of plutonium in a lung or wound. Quick assessment of personnel contamination is essential for time-critical medical intervention. In addition to pulling the trailer, the Hot Spot Truck also stores some of the …
Date: August 27, 1999
Creator: Buddemeier, B.
System: The UNT Digital Library
Removal of heavy metals from aqueous waste streams using surface-modified nanosized TiO{sub 2} photocatalysts. (open access)

Removal of heavy metals from aqueous waste streams using surface-modified nanosized TiO{sub 2} photocatalysts.

Titanium dioxide (TiO{sub 2}) colloidal particles ({approximately}45{angstrom}) whose surfaces were modified with chelating agents for photocatalytic removal of heavy-metal ions and their subsequent reduction to metallic form were investigated. Experiments were performed on nanoparticle TiO{sub 2} colloids derivatized with bidentate and tridentate ligands (thiolactic acid [TLA], cysteine, and alanine [ALA]) in batch mode in a photoreactor with 254nm light. We used catalysts designed and synthesized for selective and efficient removal of Pb and Cu with and without added hole scavenger (methanol). Parallel experiments also have been carried out in the dark to study metal ion adsorption properties. Solutions have been filtered to remove TiO{sub 2}, and metal particulates. Both the native solution and the metal deposited on the nanocrystalline TiO{sub 2} particles were analyzed. Results demonstrate that for the case of lead, the most effective TiO{sub 2} surface modifier was TLA (&gt;99% Pb(II) removed from solution). Experiments performed to study Cn removal using TiO{sub 2} colloids modified with alanine showed that copper ions were effectively removed and reduced to metallic form in the presence of methanol.
Date: August 27, 1998
Creator: Meshkov, N. K.
System: The UNT Digital Library
Incident spectrum determination for time-of-flight neutron powder diffraction data analysis. (open access)

Incident spectrum determination for time-of-flight neutron powder diffraction data analysis.

Accurate characterization of the incident neutron spectrum is an important requirement for precise Rietveld analysis of time-of-flight powder neutron diffraction data. Without an accurate incident spectrum the calculated model for the measured relative intensities of individual Bragg reflections will possess systematic errors. We describe a method for obtaining an accurate numerical incident spectrum using data from a transmitted beam monitor.
Date: August 27, 1998
Creator: Hodges, J. P.
System: The UNT Digital Library
Simulation of intense heating and shock hydrodynamics in free-moving liquid targets. (open access)

Simulation of intense heating and shock hydrodynamics in free-moving liquid targets.

Recently, significant interest has focused on the use of free or open liquid-metal targets flowing with high velocities in various nuclear and high-energy physics applications such as the ISOLDE and muon collider projects. This is because the heat generated in solid targets due to beam bombardment cannot be removed easily and the resulting thermal shock damage is a serious problem. The behavior of a free-moving liquid mercury or gallium jet due to a proton beam deposition in a strong magnetic field has been modeled and analyzed for the muon collider project. Free liquid-metal jets offer significant advantages over conventional solid targets, particularly for the more demanding and challenging high-power applications.
Date: August 27, 1999
Creator: Hassanein, A.
System: The UNT Digital Library
Measurement of the critical current and transient characteristics of a high-temperature superconductor tube using a pulsed current supply. (open access)

Measurement of the critical current and transient characteristics of a high-temperature superconductor tube using a pulsed current supply.

The transient response of a melt-cast-processed BSCCO-2212 superconductor tube is investigated by using a pulsed current source. It was found that (1) the maximum induced current and the excitation current at field penetration increase with the maximum excitation current, and (2) there is a time delay between peak excitation current and peak magnetic field inside the superconductor. These observations can be explained by the concept of magnetic diffusion. The ac steady-state critical current of the superconductor was found to depend on the magnitude of the current increment. The critical current determined by using the pulsed current system agrees fairly well with the ac steady-state critical current determined by using relatively large current increment.
Date: August 27, 1998
Creator: Cha, Y. S.
System: The UNT Digital Library
Using synthetic model systems to understand charge separation and spin dynamics in photosynthetic reaction centers. (open access)

Using synthetic model systems to understand charge separation and spin dynamics in photosynthetic reaction centers.

Our current work in modeling reaction center dynamics has resulted in the observation of each major spin-dependent photochemical pathway that is observed in reaction centers. The development of new, simpler model systems has permitted us to probe deeply into the mechanistic issues that drive these dynamics. Based on these results we have returned to biomimetic chlorophyll-based electron donors to mimic these dynamics. Future studies will focus on the details of electronic structure and energetic of both the donor-acceptor molecules and their surrounding environment that dictate the mechanistic pathways and result in efficient photosynthetic charge separation.
Date: August 27, 1998
Creator: Wasielewski, M. R.
System: The UNT Digital Library
Graphical user interfaces for McCellan Nuclear Radiation Center (MNRC). (open access)

Graphical user interfaces for McCellan Nuclear Radiation Center (MNRC).

McClellan's Nuclear Radiation Center (MNRC) control console is in the process of being replaced due to spurious scrams, outdated software, and obsolete parts. The intent of the new control console is to eliminate the existing problems by installing a UNIX-based computer system with industry-standard interface software and incorporating human factors during all stages of the graphical user interface (GUI) development and control console design.
Date: August 27, 1998
Creator: Brown-VanHoozer, S. A.
System: The UNT Digital Library
Generation of partially coherent stationary time histories with non-Gaussian distributions (open access)

Generation of partially coherent stationary time histories with non-Gaussian distributions

In a previous paper Smallwood and Paez (1991) showed how to generate realizations of partially coherent stationary normal time histories with a specified cross-spectral density matrix. This procedure is generalized for the case of multiple inputs with a specified cross-spectral density function and a specified marginal probability density function (pdf) for each of the inputs. The specified pdfs are not required to be Gaussian. A zero memory nonlinear (ZMNL) function is developed for each input to transform a Gaussian or normal time history into a time history with a specified non-Gaussian distribution. The transformation functions have the property that a transformed time history will have nearly the same auto spectral density as the original time history. A vector of Gaussian time histories are then generated with the specified cross-spectral density matrix. These waveforms are then transformed into the required time history realizations using the ZMNL function.
Date: August 27, 1996
Creator: Smallwood, D.O.
System: The UNT Digital Library
Defense against common mode failures in protection system design (open access)

Defense against common mode failures in protection system design

The introduction of digital instrumentation and control into reactor safety systems creates a heightened concern about common-mode failure. This paper discusses the concern and methods to cope with the concern. Common-mode failures have been a ``fact-of-life`` in existing systems. The informal introduction of defense-in-depth and diversity (D-in-D&D)-coupled with the fact that hardware common-mode failures are often distributed in time-has allowed systems to deal with past common-mode failures. However, identical software operating in identical redundant systems presents the potential for simultaneous failure. Consequently, the use of digital systems raises the concern about common-mode failure to a new level. A more methodical approach to mitigating common-mode failure is needed to address these concerns. Purposeful introduction of D-in-D&D has been used as a defense against common-mode failure in reactor protection systems. At least two diverse systems are provided to mitigate any potential initiating event. Additionally, diverse displays and controls are provided to allow the operator to monitor plant status and manually initiate engineered safety features. A special form of conimon-mode failure analysis called ``defense-in-depth and diversity analysis`` has been developed to identify possible conimon-mode failure vulnerabilities in digital systems. An overview of this analysis technique is provided.
Date: August 27, 1997
Creator: Wyman, R. H. & Johnson, G. L.
System: The UNT Digital Library
Societal health and urban sustainability indicators (open access)

Societal health and urban sustainability indicators

Without the social will, no city can successfully Undertake the planning and programs necessary for meaningful progress toward sustainability. Social will derives from wellsprings of vital societal health. This paper presents an approach to helping cities in APEC member economies initiate a program for developing indicators of sustainability. Representative indicators of social capital and other aspects of civic engagement, as proxies for societal health, are presented.
Date: August 27, 1996
Creator: Petrich, C.H. & Tonn, B.E.
System: The UNT Digital Library
Hidden quasars in ultraluminous infared galaxies (open access)

Hidden quasars in ultraluminous infared galaxies

Abstract. Many ultraluminous infrared galaxies (ULIRGS) are pow- ered by quasars hidden in the center, but many are also powered by starbursts. A simply diagnostic diagram is proposed that can iden- tify obscured quasars in ULIRGs by their high-ionization emission lines ([0 III]X5007/HP ,? 5), and �warm� IR color (&/f6s 2 0.25).
Date: August 27, 1998
Creator: Brotherton, M. S.; Stanford, S. A.; Tran, H. & van Breugel, W.
System: The UNT Digital Library
Spatial frequency domain error budget (open access)

Spatial frequency domain error budget

The aim of this paper is to describe a methodology for designing and characterizing machines used to manufacture or inspect parts with spatial-frequency-based specifications. At Lawrence Livermore National Laboratory, one of our responsibilities is to design or select the appropriate machine tools to produce advanced optical and weapons systems. Recently, many of the component tolerances for these systems have been specified in terms of the spatial frequency content of residual errors on the surface. We typically use an error budget as a sensitivity analysis tool to ensure that the parts manufactured by a machine will meet the specified component tolerances. Error budgets provide the formalism whereby we account for all sources of uncertainty in a process, and sum them to arrive at a net prediction of how "precisely" a manufactured component can meet a target specification. Using the error budget, we are able to minimize risk during initial stages by ensuring that the machine will produce components that meet specifications before the machine is actually built or purchased. However, the current error budgeting procedure provides no formal mechanism for designing machines that can produce parts with spatial-frequency-based specifications. The output from the current error budgeting procedure is a single number …
Date: August 27, 1998
Creator: Hauschildt, H & Krulewich, D
System: The UNT Digital Library
ULTRADENSE QUARK STARS FROM PERTURBATIVE QCD. (open access)

ULTRADENSE QUARK STARS FROM PERTURBATIVE QCD.

None
Date: August 27, 2000
Creator: FRAGA,E.S.
System: The UNT Digital Library
The CDF Run 2 Offline Computer Farms (open access)

The CDF Run 2 Offline Computer Farms

Run 2 at Fermilab began in March 2001. CDF will collect data at a maximum rate of 20 MByte/sec during the run. The offline reconstruction of this data must keep up with the data taking rate. This reconstruction occurs on a large PC farm, which must have the capacity for quasi-real time data reconstruction, for reprocessing of some data and for generation and processing of Monte Carlo samples. In this paper they give the design requirements for the farm, describe the hardware and software design used to meet those requirements, describe the early experiences with Run 2 data processing, and discuss future prospects for the farm, including some ideas about Run 2b processing.
Date: August 27, 2001
Creator: al., Jaroslav Antos et
System: The UNT Digital Library
The CDF data acquisition system for Tevatron Run II (open access)

The CDF data acquisition system for Tevatron Run II

The CDF experiment at the Fermilab Tevatron has been significantly upgraded for the collider Run II, which started in March 2001 and is scheduled to last until 2006. Instantaneous luminosities of 10{sup 32} cm{sup -2} s{sup -1} and above are expected. A data acquisition system capable of efficiently recording the data has been one of the most critical elements of the upgrade. Key figures are the ability to deal with the short bunch spacing of 132 ns, event sizes of the order of 250 kB, and permanent logging of 20 MB/s. The design of the system and experience from the first months of data-taking operation are discussed.
Date: August 27, 2001
Creator: Meyer, Arnd
System: The UNT Digital Library
In-Situ STM Studies of Strain Stabilized Thin Film Dislocation Networks Under Applied Stress (open access)

In-Situ STM Studies of Strain Stabilized Thin Film Dislocation Networks Under Applied Stress

None
Date: August 27, 2000
Creator: Schaff, O.; Schmid, A. K.; Bartelt, N. C.; Figuera, J. de la & Hwang, R. Q.
System: The UNT Digital Library
Symposium on microscale separations and analysis. Final Technical Report (open access)

Symposium on microscale separations and analysis. Final Technical Report

The ''Symposium on Microscale Separations and Analysis'' event, held as a section of the American Chemical Society Annual meeting on 27 August 2001, brought together engineers, physicists, and chemists from both academia and industry to discuss the latest research in the area of biomolecule analysis on microfluidic devices for genomic and proteomic applications.
Date: August 27, 2001
Creator: unknown
System: The UNT Digital Library
Giving effective poster presentations (open access)

Giving effective poster presentations

Giving an effective poster presentation can be easy and rewarding with attention to a few proven concepts. Define your audience. Keep the words and graphics clear, concise, and eye-catching. Remember, you have three seconds to attract attention and 30 seconds to get your message across.
Date: August 27, 1998
Creator: Rice, J A
System: The UNT Digital Library