AN ASSESSMENT OF SIMPLIFIED VS. DETAILED METHODOLOGIES FOR SSI ANALYSES OF DEEPLY EMBEDDED STRUCTURES. (open access)

AN ASSESSMENT OF SIMPLIFIED VS. DETAILED METHODOLOGIES FOR SSI ANALYSES OF DEEPLY EMBEDDED STRUCTURES.

Sponsored by the US Nuclear Regulatory Commission (NRC), Brookhaven National Laboratory (BNL) is carrying out a research program to develop a technical basis to support the safety evaluation of deeply embedded and/or buried (DEB) structures as proposed for advanced reactor designs. In this program, the methods and computer programs established for the assessment of soil-structure interaction (SSI) effects for the current generation of light water reactors are evaluated to determine their applicability and adequacy in capturing the seismic behavior of DEB structures. This paper presents an assessment of the simplified vs. detailed methodologies for seismic analyses of DEB structures. In this assessment, a lump-mass beam model is used for the simplified approach and a finite element representation is employed for the detailed method. A typical containment structure embedded in a soil profile representative of a typical nuclear power plant site was utilized, considering various embedment depths from shallow to full burial. BNL used the CARES program for the simplified model and the SASSI2000 program for the detailed analyses. The calculated response spectra at the key locations of the DEB structure are used for the performance assessment of the applied methods for different depths of burial. Included in the paper are: …
Date: March 4, 2004
Creator: XU,J. MILLER,C. HOFMAYER,C. GRAVES,H.
System: The UNT Digital Library
Beat wave injection of electrons into plasma waves using two interfering laser pulses (open access)

Beat wave injection of electrons into plasma waves using two interfering laser pulses

An electron injector concept that uses a single injection laser pulse colliding with a pump laser pulse in a plasma is analyzed. The pump pulse generates a large amplitude laser wakefield (plasma wave). The counter propagating injection pulse collides with the pump laser pulse to generate a beat wave with a slow phase velocity. The ponderomotive force of the slow beat wave is responsible for injecting plasma electrons into the wakefield near the back of the pump pulse. Test particle simulations indicate that significant amounts of charge can be trapped and accelerated ({approx} 10 pC). For higher charge, beam loading limits the validity of the simulations. The accelerated bunches are ultrashort ({approx} 1 fs) with good beam quality (relative energy spread of a few percent at a mean energy of {approx} 10 MeV and a normalized rms emittance on the order 0.4 mm.mrad). The effects of interaction angle and polarization are also explored, e.g., efficient trapping can occur for near-collinear geometries. Beat wave injection using a single injection pulse has the advantages of simplicity, ease of experimental implementation, and requires modest laser intensity I {approx_equal} 8.8 x 10{sup 17} W/cm{sup 2}.
Date: March 4, 2004
Creator: Fubiani, G.; Esarey, E.; Schroeder, C. B. & Leemans, W. P.
System: The UNT Digital Library
Comment regarding"On the Crooks fluctuation theorem and the Jarzynski equality" [J. Chem. Phys. 129, 091101 (2008)]and"Nonequilibrium fluctuation-dissipation theorem of Brownian dynamics" [J. Chem. Phys. 129, 144113 (2008)] (open access)

Comment regarding"On the Crooks fluctuation theorem and the Jarzynski equality" [J. Chem. Phys. 129, 091101 (2008)]and"Nonequilibrium fluctuation-dissipation theorem of Brownian dynamics" [J. Chem. Phys. 129, 144113 (2008)]

The incongruous"unexpected inapplicability of the [Crook's fluctuation theorem]" is due to an inexplicable, inappropriate use of inconsistent expressions. The girding is secure.
Date: March 4, 2009
Creator: Crooks, Gavin E
System: The UNT Digital Library
Continuing Studies on Direct Aqueous Mineral Carbonation of CO{sub 2} Sequestration (open access)

Continuing Studies on Direct Aqueous Mineral Carbonation of CO{sub 2} Sequestration

Direct aqueous mineral carbonation has been investigated as a process to convert gaseous CO{sub 2} into a geologically stable, solid final form. The process utilizes a solution of sodium bicarbonate (NaHCO{sub 3}), sodium chloride (NaCl), and water, mixed with a mineral reactant, such as olivine (Mg{sub 2}SiO{sub 4}) or serpentine [Mg{sub 3}Si{sub 2}O{sub 5}(OH){sub 4}]. Carbon dioxide is dissolved into this slurry, by diffusion through the surface and gas dispersion within the aqueous phase. The process includes dissolution of the mineral and precipitation of the magnesium carbonate mineral magnesite (MgCO{sub 3}) in a single unit operation. Activation of the silicate minerals has been achieved by thermal and mechanical means, resulting in up to 80% stoichiometric conversion of the silicate to the carbonate within 30 minutes. Heat treatment of the serpentine, or attrition grinding of the olivine and/or serpentine, appear to activate the minerals by the generation of a non-crystalline phase. Successful conversion to the carbonate has been demonstrated at ambient temperature and relatively low (10 atm) partial pressure of CO{sub 2} (P{sub CO2}). However, optimum results have been achieved using the bicarbonate-bearing solution, and high P{sub CO2}. Specific conditions include: 185 C; P{sub CO2}=150 atm; 30% solids. Studies suggest that …
Date: March 4, 2002
Creator: O'Connor, W. K.; Dahlin, D. C.; Nilsen, D. N.; Gerdemann, S. J.; Rush, G. E.; Penner, L. R. et al.
System: The UNT Digital Library
Critical Soil-Structure Interaction Analysis Considerations for Seismic Qualification of Safety Equipment (open access)

Critical Soil-Structure Interaction Analysis Considerations for Seismic Qualification of Safety Equipment

While developing seismic analysis models for buildings that support safety-related equipment, a number of issues should be considered to ensure that the input motions for performing seismic qualification of safety-related equipment are properly defined. These considerations are listed and discussed here with special attention to the effect and importance of the interaction among the foundation soil, the building structure, the equipment anchors, and the equipment structure. Typical industry practices are critically examined to assess their adequacy for determining the input motions for equipment seismic qualification. The features that are considered essential in a soil-structure interaction (SSI) model are described. Also, the effects of inappropriate treatment or representation of these features are discussed.
Date: March 4, 2004
Creator: Hossain, Q A
System: The UNT Digital Library
Crystal Structure of the Bromide-Bound D85S Mutant of Bacteriorhodopsin: Principles of Ion Pumping (open access)

Crystal Structure of the Bromide-Bound D85S Mutant of Bacteriorhodopsin: Principles of Ion Pumping

None
Date: March 4, 2004
Creator: Facciotti, Marc T.; Cheung, Vincent S.; Nguyen, Doris; Rouhani, Shahab & Glaeser, Robert M.
System: The UNT Digital Library
Delta to Alpha-Prime Phase Transformation in a Pu-Ga Alloy Under Hydrostatic Pressure (open access)

Delta to Alpha-Prime Phase Transformation in a Pu-Ga Alloy Under Hydrostatic Pressure

None
Date: March 4, 2008
Creator: Schwartz, A J; Wall, M A; Farber, D L; Moore, K T & Blobaum, K M
System: The UNT Digital Library
Detection and Tracking of the Back-Reflection of KDP Images in the Presence or Absence of a Phase Mask (open access)

Detection and Tracking of the Back-Reflection of KDP Images in the Presence or Absence of a Phase Mask

The KDP crystals present in the final optics assembly at the National Ignition Facility (NIF) are used for conversion of infrared laser light beam into ultraviolet. The conversion is highest for a certain incident angle, the alignment of which is determined from the position of the back reflection beam, which exhibits a distinct characteristics shape. When a phase plate device is introduced before the final assembly to increase the uniformity of the beam, the back reflection pattern changes drastically. The algorithm which is best for tracking the special shaped beam is no longer suitable to track the phase modified beam. The work presented here discusses our detection schemes for both the situations. In particular, we demonstrate how the algorithm senses the modified beam using a newly proposed criterion of ''correlation peak pedestal area'' and execute an alternate algorithm in real time without operator intervention. This new algorithm continuously tracks the beam pattern to guarantee reliable and repeatable sensing. Results from simulation and real world implementation of the algorithm at the NIF facility are presented.
Date: March 4, 2005
Creator: Awwal, A.; McClay, W. A.; Ferguson, S. W.; Candy, J. V.; Salmon, J. T. & Wegner, P. J.
System: The UNT Digital Library
Early universe cosmology and tests of fundamental physics (open access)

Early universe cosmology and tests of fundamental physics

This is the report of the Working Group on Early Universe Cosmology and tests of Fundamental Physics, group P4.8 of the of the Snowmass 2001 conference. Here we summarize the impressive array of advances that have taken place in this field, and identify opportunities for even greater progress in the future. Topics include Dark Energy, Cosmic Acceleration, Inflation, Phase Transitions, Baryogenesis, and String/M-theory Cosmology. The introductory section gives an executive summary with six key open questions on which we can expect to make significant progress.
Date: March 4, 2002
Creator: Andreas Albrecht, Joshua A. Frieman and Mark Trodden
System: The UNT Digital Library
Effects of Tritium in Elastomers (open access)

Effects of Tritium in Elastomers

A number of elastomers, used as flange gaskets in the piping system of the Savannah River Plant tritium facilities, are being examined to identify those compounds more radiation-resistant that the currently specified Buna-N rubber and to study the mechanism of tritium radiation damage. This paper discusses this study.
Date: March 4, 2003
Creator: Zapp, P.E.
System: The UNT Digital Library
Electrical Safety and Arc Flash Protections (open access)

Electrical Safety and Arc Flash Protections

Over the past four years, the Electrical Safety Program at PPPL has evolved in addressing changing regulatory requirements and lessons learned from accident events, particularly in regards to arc flash hazards and implementing NFPA 70E requirements. This presentation will discuss PPPL's approaches to the areas of electrical hazards evaluation, both shock and arc flash; engineered solutions for hazards mitigation such as remote racking of medium voltage breakers, operational changes for hazards avoidance, targeted personnel training and hazard appropriate personal protective equipment. Practical solutions for nominal voltage identification and zero voltage checks for lockout/tagout will also be covered. Finally, we will review the value of a comprehensive electrical drawing program, employee attitudes expressed as a personal safety work ethic, integrated safety management, and sustained management support for continuous safety improvement.
Date: March 4, 2008
Creator: Camp, R.
System: The UNT Digital Library
A fast inversion method for interpreting borehole electromagnetic data (open access)

A fast inversion method for interpreting borehole electromagnetic data

None
Date: March 4, 2003
Creator: Kim, Hee Joon; Lee, Ki Ha & Wilt, Michael
System: The UNT Digital Library
FINAL FRONTIER AT HANFORD TACKLING THE CENTRAL PLATEAU (open access)

FINAL FRONTIER AT HANFORD TACKLING THE CENTRAL PLATEAU

The large land area in the center of the vast Department of Energy (DOE) Hanford Site in southeast Washington State is known as 'the plateau'--aptly named because its surface elevations are 250-300 feet above the groundwater table. By contrast, areas on the 585-square mile Site that border the Columbia River sit just 30-80 feet above the water table. The Central Plateau, which covers an ellipse of approximately 70 square miles, contains Hanford's radiochemical reprocessing areas--the 200 East and 200 West Areas--and includes the most highly radioactive waste and contaminated facilities on the Site. Five 'canyons' where chemical processes were used to separate out plutonium (Pu), 884 identified soil waste sites (including approximately 50 miles of solid waste burial trenches), more than 900 structures, and all of Hanford's liquid waste storage tanks reside in the Central Plateau. (Notes: Canyons is a nickname given by Hanford workers to the chemical reprocessing facilities. The 177, underground waste tanks at Hanford comprise a separate work scope and are not under Fluor's management). Fluor Hanford, a DOE prime cleanup contractor at the Site for the past 12 years, has moved aggressively to investigate Central Plateau waste sites in the last few years, digging more than …
Date: March 4, 2008
Creator: MS, GERBER
System: The UNT Digital Library
The form, distribution and mobility of arsenic in soilscontaminated by arsenic trioxide, at sites in southeast USA (open access)

The form, distribution and mobility of arsenic in soilscontaminated by arsenic trioxide, at sites in southeast USA

Soils from many industrial sites in southeastern USA arecontaminated with As because of the application of herbicide containingAs2O3. Among those contaminated sites, two industrial sites, FW and BH,which are currently active and of most serious environmental concerns,were selected to characterize the occurrence of As in the contaminatedsoils and to evaluate its environmental leachability. The soils are bothsandy loams with varying mineralogical and organic matter contents.Microwave-assisted acid digestion (EPA method 3051) of the contaminatedsoils indicated As levels of up to 325 mg/kg and 900 mg/kg (dry weightbasis) for FW and BH soils, respectively. However, bulk X-ray powderdiffraction (XRD) analysis failed to find any detectable As-bearingphases in either of the studied soil samples. Most of the soil As wasobserved by scanning electron microscopy, coupled with energy dispersiveX-ray spectroscopy (SEM/EDX), to be disseminated on the surfaces offine-grained soil particles in close association with Al and Fe. A fewAs-bearing particles were detected in BH soil using electron microprobeanalysis (EMPA). Synchrotron micro-XRD and X-ray absorption near-edgestructure (XANES) analyses indicated that these As-rich particles werepossibly phaunouxite, a mineral similar to calcium arsenate, which couldhave been formed by natural weathering after the application of As2O3.However, the scarcity of those particles eliminated them from playing anyimportant role in …
Date: March 4, 2005
Creator: Yang, Li & Donahoe, Rona J.
System: The UNT Digital Library
Generating Intense Attosecond X-Ray Pulses Using Ultraviolet-Laser-Induced Microbunching in Electron Beams (open access)

Generating Intense Attosecond X-Ray Pulses Using Ultraviolet-Laser-Induced Microbunching in Electron Beams

We propose a scheme that combines the echo-enabled harmonic generation technique with the bunch compression and allows to generate harmonic numbers of a few hundred in a microbunched beam through up-conversion of the frequency of an ultraviolet seed laser. Sending this beam through a short undulator results in an isolated sub-100 attoseconds pulse of x-ray radiation. Using a representative realistic set of parameters, we show that 1 nm x-ray pulse with peak power exceeding 100 MW and duration as short as 34 attoseconds (FWHM) can be generated from a 200 nm ultraviolet seed laser.
Date: March 4, 2009
Creator: Xiang, D.; Huang, Z. & Stupakov, G.
System: The UNT Digital Library
Generation of attosecond x-ray pulses with a multi-cycle two-color ESASE scheme (open access)

Generation of attosecond x-ray pulses with a multi-cycle two-color ESASE scheme

Generation of attosecond x-ray pulses is attracting much attention within the x-ray free-electron laser (FEL) user community. Several schemes using extremely short laser pulses to manipulate the electron bunches have been proposed. In this paper, we extend the attosecond two-color ESASE scheme proposed by Zholents et al. to the long optical cycle regime using a second detuned laser and a tapered undulator. Both lasers can be about ten-optical-cycles long, with the second laser frequency detuned from the first to optimize the contrast between the central and side current spikes. A tapered undulator mitigates the degradation effect of the longitudinal space charge (LSC) force in the undulator and suppresses the FEL gain of all side current peaks. Simulations using the LCLS parameters show a single attosecond x-ray spike of {approx} 110 attoseconds can be produced. The second laser can also be detuned to coherently control the number of the side x-ray spikes and the length of the radiation pulse.
Date: March 4, 2009
Creator: Ding, Y.; Huang, Z.; Ratner, D.; Bucksbaum, P. & Merdji, H.
System: The UNT Digital Library
High sensitivity resonance frequency measurements of individualmicro-cantilevers using fiber optical interferometry (open access)

High sensitivity resonance frequency measurements of individualmicro-cantilevers using fiber optical interferometry

We describe a setup for the resonance frequency measurement of individual microcantilevers. The setup displays both high spatial selectivity and sensitivity to specimen vibrations by utilizing a tapered uncoated fiber tip. The high sensitivity to specimen vibrations is achieved by the combination of optical Fabry-Perot interferometry and narrow band RF detection. Wave fronts reflected on the specimen and on the fiber tip end face interfere, thus no reference plane on the specimen is needed, as demonstrated with the example of freestanding silicon nitride micro-cantilevers. The resulting system is integrated in a DB-235 dual beam FIB system, thereby allowing the measurement of micro-cantilever responses during observation in SEM mode. The FIB was used to modify the optical fiber tip. At this point of our RF system development, the microcantilevers used to characterize the detector were not modified in situ.
Date: March 4, 2009
Creator: Duden, Thomas & Radmilovic, Velimir
System: The UNT Digital Library
High-speed horizontal-path atmospheric turbulence correction using a large actuator-number MEMS spatial light modulator in an interferometric phase conjugation engine (open access)

High-speed horizontal-path atmospheric turbulence correction using a large actuator-number MEMS spatial light modulator in an interferometric phase conjugation engine

Atmospheric propagation results for a high-speed, large-actuator-number, adaptive optics system are presented. The system uses a MEMS-based spatial light modulator correction device with 1024 actuators. Tests over a 1.35 km path achieved correction speeds in excess of 800 Hz and Strehl ratios close to 0.5. The wave-front sensor was based on a quadrature interferometer that directly measures phase. This technique does not require global wave-front reconstruction, making it relatively insensitive to scintillation and phase residues. The results demonstrate the potential of large actuator number MEMS-based spatial light modulators to replace conventional deformable mirrors.
Date: March 4, 2004
Creator: Baker, K.; Stappaerts, E.; Gavel, D.; Wilks, S.; Tucker, J.; Silva, D. et al.
System: The UNT Digital Library
ILC Marx Modulator Development Program Status (open access)

ILC Marx Modulator Development Program Status

Development of a first generation prototype (P1) Marx-topology klystron modulator for the International Linear Collider is nearing completion at the Stanford Linear Accelerator Center. It is envisioned as a smaller, lower cost, and higher reliability alternative to the present, bouncer-topology, 'Baseline Conceptual Design'. The Marx presents several advantages over conventional klystron modulator designs. It is physically smaller; there is no pulse transformer (quite massive at ILC parameters) and the energy storage capacitor bank is quite small, owing to the active droop compensation. It is oil-free; voltage hold-off is achieved using air insulation. It is air cooled; the secondary air-water heat exchanger is physically isolated from the electronic components. The P1-Marx employs all solid state elements; IGBTs and diodes, to control the charge, discharge and isolation of the cells. A general overview of the modulator design and the program status are presented.
Date: March 4, 2009
Creator: Burkhart, C.; Beukers, T.; Larsen, R.; Macken, K.; Nguyen, M.; Olsen, J. et al.
System: The UNT Digital Library
Improving the performance of the actinic inspection tool with an optimized alignment procedure (open access)

Improving the performance of the actinic inspection tool with an optimized alignment procedure

Extreme ultraviolet (EUV) microscopy is an important tool for the investigation of the performance of EUV masks, for detecting the presence and the characteristics of defects, and for evaluating the effectiveness of defect repair techniques. Aerial image measurement bypasses the difficulties inherent to photoresist imaging and enables high data collection speed and flexibility. It provides reliable and quick feedback for the development of masks and lithography system modeling methods. We operate the SEMATECH Berkeley Actinic Inspection Tool (AIT), a EUV microscope installed at the Advanced Light Source at Lawrence Berkeley National Laboratory. The AIT is equipped with several high-magnification Fresnel zoneplate lenses, with various numerical aperture values, that enable it image the reflective mask surface with various resolution and magnification settings. Although the AIT has undergone significant recent improvements in terms of imaging resolution and illumination uniformity, there is still room for improvement. In the AIT, an off-axis zoneplate lens collects the light coming from the sample and an image of the sample is projected onto an EUV-sensitive CCD camera. The simplicity of the optical system is particularly helpful considering that the AIT alignment has to be performed every time that a sample or a zoneplate is replaced. The alignment …
Date: March 4, 2009
Creator: Mochi, I.; Goldberg, K.A.; Naulleau, P. & Huh, Sungmin
System: The UNT Digital Library
International X-Band Linear Collider Accelerator Structure R&D (open access)

International X-Band Linear Collider Accelerator Structure R&D

For more than fifteen years before the International Technology Recommendation Panel (ITRP) decision in August, 2004, there were intensive R&D activities and broad international collaboration among the groups at SLAC, KEK, FNAL, LLNL and other labs for the room temperature X-Band accelerator structures. The goal was to provide an optimized design of the main linac structure for the NLC (Next Linear Collider) or GLC (Global Linear Collider). There have been two major challenges in developing X-band accelerator structures for the linear colliders. The first is to demonstrate stable, long-term operation at the high gradient (65 MV/m) that is required to optimize the machine cost. The second is to strongly suppress the beam induced long-range wakefields, which is required to achieve high luminosity. More than thirty X-band accelerator structures with various RF parameters, cavity shapes and coupler types have been fabricated and tested since 1989. A summary of the main achievements and experiences are presented in this talk including the structure design, manufacturing techniques, high power performance, and other structure related issues. Also, the new progress in collaborating with the CLIC, high gradient structures and X-Band structure applications for RF deflectors and others are briefly introduced.
Date: March 4, 2009
Creator: Wang, J. W.
System: The UNT Digital Library
Multivariate Clustering of Large-Scale Simulation Data (open access)

Multivariate Clustering of Large-Scale Simulation Data

Simulations of complex scientific phenomena involve the execution of massively parallel computer programs. These simulation programs generate large-scale data sets over the spatiotemporal space. Modeling such massive data sets is an essential step in helping scientists discover new information from their computer simulations. In this paper, we present a simple but effective multivariate clustering algorithm for large-scale scientific simulation data sets. Our algorithm utilizes the cosine similarity measure to cluster the field variables in a data set. Field variables include all variables except the spatial (x, y, z) and temporal (time) variables. The exclusion of the spatial space is important since 'similar' characteristics could be located (spatially) far from each other. To scale our multivariate clustering algorithm for large-scale data sets, we take advantage of the geometrical properties of the cosine similarity measure. This allows us to reduce the modeling time from O(n{sup 2}) to O(n x g(f(u))), where n is the number of data points, f(u) is a function of the user-defined clustering threshold, and g(f(u)) is the number of data points satisfying the threshold f(u). We show that on average g(f(u)) is much less than n. Finally, even though spatial variables do not play a role in building …
Date: March 4, 2003
Creator: Eliassi-Rad, T. & Critchlow, T.
System: The UNT Digital Library
Open and hidden charm production in dA collisions at RHIC andLHC (open access)

Open and hidden charm production in dA collisions at RHIC andLHC

We discuss aspects of open and hidden charm production in deuterium-nucleus collisions at RHIC and LHC energies. We describe calculations of the total c{bar c} cross section and the charm quark transverse momentum distributions. We next explain how shadowing and moderate nuclear absorption can explain the PHENIX J/{psi} dAu/pp ratios and predict the combined effect of shadowing and absorption in 6.2 TeV d+Pb collisions.
Date: March 4, 2005
Creator: Vogt, R.
System: The UNT Digital Library
Preliminary assessment of the availability of U.S. natural gas resources to meet U.S. transportation energy demand. (open access)

Preliminary assessment of the availability of U.S. natural gas resources to meet U.S. transportation energy demand.

Recent studies have indicated that substitutes for conventional petroleum resources will be needed to meet U.S. transportation energy demand in the first half of this century. One possible substitute is natural gas which can be used as a transportation fuel directly in compressed natural gas or liquefied natural gas vehicles or as resource fuel for the production of hydrogen for fuel cell vehicles. This paper contains a preliminary assessment of the availability of U.S. natural gas resources to meet future U.S. transportation fuel demand. Several scenarios of natural gas demand, including transportation demand, in the U.S. to 2050 are developed. Natural gas resource estimates for the U. S. are discussed. Potential Canadian and Mexican exports to the U.S. are estimated. Two scenarios of potential imports from outside North America are also developed. Considering all these potential imports, U.S. natural gas production requirements to 2050 to meet the demand scenarios are developed and compared with the estimates of U.S. natural gas resources. The comparison results in a conclusion that (1) given the assumptions made, there are likely to be supply constraints on the availability of U.S. natural gas supply post-2020 and (2) if natural gas use in transportation grows substantially, it …
Date: March 4, 2002
Creator: Singh, M. K. & Moore, J. S.
System: The UNT Digital Library