Modeling Free Convection Flow of Liquid Hydrogen within a Cylindrical Heat Exchanger Cooled to 14 K (open access)

Modeling Free Convection Flow of Liquid Hydrogen within a Cylindrical Heat Exchanger Cooled to 14 K

None
Date: May 8, 2004
Creator: Green, Michael A.; Yang, S. W.; Green, M. A. & Lau, W.
Object Type: Article
System: The UNT Digital Library
Tropical Warm Pool International Cloud Experiment (TWP-ICE): Cloud and Rain Characteristics in the Australian Monsoon (open access)

Tropical Warm Pool International Cloud Experiment (TWP-ICE): Cloud and Rain Characteristics in the Australian Monsoon

The impact of oceanic convection on its environment and the relationship between the characteristics of the convection and the resulting cirrus characteristics is still not understood. An intense airborne measurement campaign combined with an extensive network of ground-based observations is being planned for the region near Darwin, Northern Australia, during January-February, 2006, to address these questions. The Tropical Warm Pool – International Cloud Experiment (TWP-ICE) will be the first field program in the tropics that attempts to describe the evolution of tropical convection, including the large scale heat, moisture, and momentum budgets, while at the same time obtaining detailed observations of cloud properties and the impact of the clouds on the environment. The emphasis will be on cirrus for the cloud properties component of the experiment. Cirrus clouds are ubiquitous in the tropics and have a large impact on their environment but the properties of these clouds are poorly understood. A crucial product from this experiment will be a dataset suitable to provide the forcing and testing required by cloud-resolving models and parameterizations in global climate models. This dataset will provide the necessary link between cloud properties and the models that are attempting to simulate them. The experiment is a …
Date: May 30, 2004
Creator: May, P. T.; Jakob, C. & Mather, J. H.
Object Type: Report
System: The UNT Digital Library
Streamlined Approach for Environmental Restoration Plan for Corrective Action Unit 496: Buried Rocket Site, Antelope Lake, Tonopah Test Range (open access)

Streamlined Approach for Environmental Restoration Plan for Corrective Action Unit 496: Buried Rocket Site, Antelope Lake, Tonopah Test Range

This Streamlined Approach for Environmental Restoration (SAFER) plan details the activities necessary to close Corrective Action Unit 496: Buried Rocket Site, Antelope Lake. CAU 496 consists of one site located at the Tonopah Test Range, Nevada.
Date: May 1, 2004
Creator: United States. National Nuclear Security Administration. Nevada Site Office.
Object Type: Report
System: The UNT Digital Library
ASIC Development for Three-Dimensional Silicon Imaging Array for Cold Neutrons (open access)

ASIC Development for Three-Dimensional Silicon Imaging Array for Cold Neutrons

An Integrated Circuit (IC) readout chip with four channels arranged so as to receive input charge from the corners of the chip was designed for use with 5- to 7-mm pixel detectors. This Application Specific IC (ASIC) can be used for cold neutron imaging, for study of structural order in materials using cold neutron scattering or for particle physics experiments. The ASIC is fabricated in a 0.5-{micro}m n-well AMI process. The design of the ASIC and the test measurements made is reported. Noise measurements are also reported.
Date: May 19, 2004
Creator: Britton, C.L.; Jagadish, U. & Bryan, W.L.
Object Type: Report
System: The UNT Digital Library
Modeling Free Convection Flow of Liquid Hydrogen within a Cylindrical Heat Exchanger Cooled to 14 K (open access)

Modeling Free Convection Flow of Liquid Hydrogen within a Cylindrical Heat Exchanger Cooled to 14 K

A liquid hydrogen in a absorber for muon cooling requires that up to 300 W be removed from 20 liters of liquid hydrogen. The wall of the container is a heat exchanger between the hydrogen and 14 K helium gas in channels within the wall. The warm liquid hydrogen is circulated down the cylindrical walls of the absorber by free convection. The flow of the hydrogen is studied using FEA methods for two cases and the heat transfer coefficient to the wall is calculated. The first case is when the wall is bare. The second case is when there is a duct some distance inside the cooled wall.
Date: May 8, 2004
Creator: Green, Michael A.; Yang, S. W.; Green, M. A. & Lau, W.
Object Type: Article
System: The UNT Digital Library
Developing a next-generation community college curriculum forenergy-efficient high-performance building operations (open access)

Developing a next-generation community college curriculum forenergy-efficient high-performance building operations

The challenges of increased technological demands in today's workplace require virtually all workers to develop higher-order cognitive skills including problem solving and systems thinking in order to be productive. Such ''habits of mind'' are viewed as particularly critical for success in the information-based workplace, which values reduced hierarchy, greater worker independence, teamwork, communications skills, non-routine problem solving, and understanding of complex systems. The need is particularly compelling in the buildings arena. To scope the problem, this paper presents the results of interviews and focus groups--conducted by Oakland California's Peralta Community College District and Lawrence Berkeley National Laboratory--in which approximately 50 industry stakeholders discussed contemporary needs for building operator education at the community college level. Numerous gaps were identified between the education today received by building operators and technicians and current workplace needs. The participants concurred that many of the problems seen today in achieving and maintaining energy savings in buildings can be traced to inadequacies in building operation and lack of awareness and knowledge about how existing systems are to be used, monitored, and maintained. Participants and others we interviewed affirmed that while these issues are addressed in various graduate-level and continuing education programs, they are virtually absent at the …
Date: May 1, 2004
Creator: Crabtree, Peter; Kyriakopedi, Nick; Mills, Evan; Haves, Philip; Otto, Roland J.; Piette, Mary Ann et al.
Object Type: Article
System: The UNT Digital Library
'Shim pulses' for NMR spectroscopy in inhomogeneous magneticfields (open access)

'Shim pulses' for NMR spectroscopy in inhomogeneous magneticfields

NMR spectroscopy conveys information about chemical structure through ppm-scale shifts of the resonance frequency depending on the chemical environment. In order to observe these small shifts, magnets with highly homogeneous magnetic field B{sub 0} are used. The high cost and large size of these magnets are a consequence of the requirement for high homogeneity. In this contribution we introduce a new method for recording high-resolution NMR spectra from samples in inhomogeneous B{sub 0}, opening up the possibility of exploiting magnets of lower homogeneity and cost. Instead of using the traditional B{sub 0} ''shim coils'', adiabatic radiofrequency (RF) pulse sequences and modulated B{sub 0} gradients generated by coils in the probe are used to produce ''shim pulses''. A great deal of work has been devoted to finding methods for retrieving chemical shift information even when B{sub 0} is inhomogeneous. One class of methods relies on zero- or multiple quantum coherences which evolve independently of B{sub 0}. These methods are inherently two-dimensional and the high-resolution information is obtained indirectly. In order to minimize experimental time it is desirable to acquire a high-resolution spectrum directly just as for traditional NMR in homogeneous fields. A further advantage with direct acquisition is that modification of …
Date: May 19, 2004
Creator: Topgaard, Daniel; Martin, Rachel W.; Sakellariou, Dimitris; Meriles, Carlos & Pines, Alexander
Object Type: Article
System: The UNT Digital Library
Small-Column Ion-Exchange Alternative to Remove 137Cs from Low-Curie Salt Waste: Summary of Phase 1 (open access)

Small-Column Ion-Exchange Alternative to Remove 137Cs from Low-Curie Salt Waste: Summary of Phase 1

A Small-Column Ion-Exchange (SCIX) system is being evaluated for removing cesium from the Type 2 and/or Type 3 dissolved saltcake wastes at the Savannah River Site (SRS) to ensure that the dissolved saltcake meets the waste acceptance criteria at the Saltstone Facility. Both crystalline silicotitanate (CST) and IONSIV{trademark} IE-96 zeolite were evaluated as the ion-exchange media. The accelerated alternative, using CST in the SCIX, could save as much as $3 billion in operating and storage costs and {approx}20 years in processing time compared to the current baseline. With its proven high cesium-loading capacity for the expected dissolved saltcake compositions and temperatures, CST is the preferred sorbent for SCIX. The low-cost alternative sorbent, zeolite, greatly increases the volume of sorbent required because of its much lower cesium-loading capacity. Thus, zeolite greatly increases the cost for the alternative, mainly because of the increased number of Defense Waste Processing Facility canisters required to dispose of the loaded sorbent (potentially over 7000 for zeolite, compared with <500 for CST). The models previously developed for predicting cesium loading on CST compared favorably with laboratory measurements of equilibrium distribution ratios and column loading performance using dissolved saltcake simulants. These models predict that a column of 432 …
Date: May 12, 2004
Creator: Walker, J. F. Jr.
Object Type: Report
System: The UNT Digital Library
Clothes washer standards in China -- The problem of water andenergy trade-offs in establishing efficiency standards (open access)

Clothes washer standards in China -- The problem of water andenergy trade-offs in establishing efficiency standards

Currently the sales of clothes washers in China consist ofseveral general varieties. Some use more energy (with or withoutincluding hot water energy use) and some use more water. Both energy andwater are in short supply in China. This poses the question - how do youtrade off water versus energy in establishing efficiency standards? Thispaper discusses how China dealt with this situation and how itestablished minimum efficiency standards for clothes washers.
Date: May 19, 2004
Creator: Biermayer, Peter J. & Lin, Jiang
Object Type: Article
System: The UNT Digital Library
Reconstruction of Sedimentary Rock Based on MechanicalProperties (open access)

Reconstruction of Sedimentary Rock Based on MechanicalProperties

We describe a general, physics-based approach to numericalreconstruction of the geometrical structure and mechanical properties ofnatural sedimentary rock in 3D. Our procedure consists of three mainsteps: sedimentation, compaction, and diagenesis, followed by theverification of rock mechanical properties. The dynamic geologicprocesses of grain sedimentation and compaction are simulated by solvinga dimensionless form of Newton's equations of motion for an ensemble ofgrains. The diagenetic rock transformation is modeled using a cementationalgorithm, which accounts for the effect of rock grain size on therelative rate of cement overgrowth. Our emphasis is on unconsolidatedsand and sandstone. The main input parameters are the grain sizedistribution, the final rock porosity, the type and amount of cement andclay minerals, and grain mechanical properties: the inter-grain frictioncoefficient, the cement strength, and the grain stiffness moduli. We usea simulated 2D Fontainebleau sandstone to obtain the grain mechanicalproperties. This Fontainebleau sandstone is also used to study theinitiation, growth, and coalescence of micro-cracks under increasingvertical stress. The box fractal dimension of the micro-crackdistribution, and its variation with the applied stress areestimated.
Date: May 4, 2004
Creator: Jin, Guodong; Patzek, Tad W. & Silin, Dmitry B.
Object Type: Report
System: The UNT Digital Library
Quantitative models of subduction zone fluids: How hydrous phases in the slab determine the composition of subduction zone lavas (open access)

Quantitative models of subduction zone fluids: How hydrous phases in the slab determine the composition of subduction zone lavas

None
Date: May 27, 2004
Creator: Feineman, M; Ryerson, F J & DePaolo, D
Object Type: Article
System: The UNT Digital Library
High-energy coherent THz radiation from laser wakefieldaccelerated ultrashort electron bunches (open access)

High-energy coherent THz radiation from laser wakefieldaccelerated ultrashort electron bunches

None
Date: May 3, 2004
Creator: van Tilborg, J.; Fubiani, G. J.; Geddes, C. G. R.; Toth, C.; Esarey, E.; Schroeder, C. B. et al.
Object Type: Article
System: The UNT Digital Library
Multi-Channel Time-Reversal Communications in a Highly Reverberative, Environment (open access)

Multi-Channel Time-Reversal Communications in a Highly Reverberative, Environment

None
Date: May 20, 2004
Creator: Candy, J V; Guidry, B L; Poggio, A J; Robbins, C & Kent, C
Object Type: Article
System: The UNT Digital Library
Behavior of Aqueous Electrolytes in Steam Cycles - The Final Report on the Solubility and Volatility of copper(I) and Copper(II) Oxides (open access)

Behavior of Aqueous Electrolytes in Steam Cycles - The Final Report on the Solubility and Volatility of copper(I) and Copper(II) Oxides

Measurements were completed on the solubility of cupric and cuprous oxides in liquid water and steam at controlled pH conditions from 25 to 400 C (77 to 752 F). The results of this study have been combined with those reported from this laboratory in two previous EPRI reports to provide a complete description of the solubility of these oxides and the speciation of copper dissolved in liquid water and steam as a function of oxidation state, temperature, pH, and in the case of steam, pressure. These constitute the first set of reliable data for cuprous oxide solubility over this range of conditions. For the more intensively studied CuO case, agreement was found between our results and those of previous studies of its solubility in steam, whereas only partial agreement was evident for its solubility in liquid water. For both oxides this disagreement often amounted to orders of magnitude. The solubility of cuprous oxide is somewhat lower than that of CuO at ambient conditions, except as very high pH. However, by 350 C (662 F), Cu{sub 2}O is the more soluble phase. At 100 C (212 F) and above, the logarithm of the solubility of both phases decreases linearly with increasing …
Date: May 1, 2004
Creator: Palmer, Donald; Benezeth, Pascale & Simonson, J Michael {Mike}
Object Type: Report
System: The UNT Digital Library
The SNM Scanner: A Non-invasive Protocol for Effective Monitoring of Special Nuclear Material Inventories (open access)

The SNM Scanner: A Non-invasive Protocol for Effective Monitoring of Special Nuclear Material Inventories

None
Date: May 20, 2004
Creator: Lanier, R G; Dauffy, L S & Hodge, A M
Object Type: Report
System: The UNT Digital Library
Theoretical study of the electronic states of Nb4, Nb5 clusters and their anions (Nb4?, Nb5?) (open access)

Theoretical study of the electronic states of Nb4, Nb5 clusters and their anions (Nb4?, Nb5?)

Geometries and energy separations of the various low-lying electronic states of Nb{sub n} and Nb{sub n}{sup -} (n = 4, 5) clusters with various structural arrangements have been investigated. The complete active space multi-configuration self-consistent field (CASMCSCF) method followed by multi-reference singles and doubles configuration interaction (MRSDCI) calculations that included up to 52 million configuration spin functions have been used to compute several electronic states of these clusters. The ground states of both Nb{sub 4} ({sup 1}A', pyramidal) and Nb{sub 4}{sup -} ({sup 2}B{sub 3g}, rhombus) are low-spin states at the MRSDCI level. The ground state of Nb{sub 5} cluster is a doublet with a distorted trigonal bipyramid (DTB) structure. The anionic cluster of Nb{sub 5} has two competitive ground states with singlet and triplet multiplicities (DTB). The low-lying electronic states of these clusters have been found to be distorted due to Jahn-Teller effect. On the basis of the energy separations of our computed electronic states of Nb{sub 4} and Nb{sub 5}, we have assigned the observed photoelectron spectrum of Nb{sub n}{sup -}(n = 4, 5) clusters. We have also compared our MRSDCI results with density functional calculations. The electron affinity, ionization potential, dissociation and atomization energies of Nb{sub 4} …
Date: May 6, 2004
Creator: Balasubramanian, K & Majumdar, D
Object Type: Article
System: The UNT Digital Library
DESIGN, CONSTRUCTION, AND STATUS OF ALL NIOBIUM SUPERCONDUCTING PHOTOINJECTOR AT BNL. (open access)

DESIGN, CONSTRUCTION, AND STATUS OF ALL NIOBIUM SUPERCONDUCTING PHOTOINJECTOR AT BNL.

We present here the design and construction of an all niobium superconducting RF injector to generate high average current, high brightness electron beam. A 1/2 cell superconducting cavity has been designed, built, and tested. A cryostat has been built to cool the cavity to {approx}2 K. The RF system can deliver up to 500 W at 1.3 GHz to the cavity. A mode-locked Nd:YVO{sub 4} laser, operating at 266 nm with 0.15 W average power, phase locked to the RF, will irradiate a laser cleaned Nb surface at the back wall of the cavity. Description of critical components and their status are presented in the paper. Based on DC measurements, QE of up to 10{sup 4} can be expected from such cavity.
Date: May 12, 2004
Creator: SRINIVASAN-RAO,T. BEN-ZVI,I. BURRILL,A. CITVER,G. ET AL.
Object Type: Article
System: The UNT Digital Library
Multi-Tube Power Leads Tower for Bepcii Ir Magnets. (open access)

Multi-Tube Power Leads Tower for Bepcii Ir Magnets.

A power lead tower containing the multi-tube power leads is designed and under fabrication for the superconducting IR quadrupole magnets in the Beijing Electron Position Collider Upgrade (BEPCII). The lead tower consists of six pairs of gas-cooled leads for seven superconducting coils at various operating currents. The power lead is designed in a modular fashion, which can be easily applied to suit different operating current. The end copper block of the tube lead has a large cold mass that provide a large time constant in case of cooling flow interruption. A novel cryogenic electrical isolator is used for the leads.
Date: May 11, 2004
Creator: Jia, L. X.; Zhang, X. B.; Wang, L.; Wang, T. H. & Yao, Z. L.
Object Type: Article
System: The UNT Digital Library
Transforming the Market for Sustainable Design: Effective Public Policies and Strategies; Preprint (open access)

Transforming the Market for Sustainable Design: Effective Public Policies and Strategies; Preprint

The federal government strives to lead by example in energy and resource management and architectural design. This paper explores how public agencies are supporting that goal by using sustainable practices in the design and operation of their buildings. It presents some elements to consider in establishing a policy for sustainable design and a system for implementing that policy, including some of the most difficult implementation issues agencies have to face. The paper also highlights some of the strengths and weaknesses of federal, state, and local policies and practices governing the design of public buildings; two case studies provide examples. Different approaches are included to help agencies evaluate their effectiveness at various levels of government. And recommendations are made for agencies and others who are committed to sustainable design in both new construction and major renovations.
Date: May 1, 2004
Creator: Carlisle, N.; Glickman, J.; Brown, M.; Foster, M.; Bennett, A. K. & Sandler, K.
Object Type: Article
System: The UNT Digital Library
Intracavity adaptive correction of a 10 kW, solid-state, heat-capacity laser (open access)

Intracavity adaptive correction of a 10 kW, solid-state, heat-capacity laser

The Solid-State, Heat-Capacity Laser (SSHCL), under development at Lawrence Livermore National Laboratory (LLNL) is a large aperture (100 cm{sup 2}), confocal, unstable resonator requiring near-diffraction-limited beam quality. There are two primary sources of the aberrations in the system: residual, static aberrations from the fabrication of the optical components and predictable, time-dependent, thermally-induced index gradients within the gain medium. A deformable mirror placed within the cavity is used to correct the aberrations that are sensed externally with a Shack-Hartmann wavefront sensor. Although the complexity of intracavity adaptive correction is greater than that of external correction, it enables control of the mode growth within the resonator, resulting in the ability to correct a more aberrated system longer. The overall system design, measurement techniques and correction algorithms are discussed. Experimental results from initial correction of the static aberrations and dynamic correction of the time-dependent aberrations are presented.
Date: May 13, 2004
Creator: LaFortune, K N; Hurd, R L; Brase, J M & Yamamoto, R M
Object Type: Article
System: The UNT Digital Library
Small Wind Electric Systems: A Wisconsin Consumer's Guide (open access)

Small Wind Electric Systems: A Wisconsin Consumer's Guide

Small Wind Electric Systems: A Wisconsin Consumer's Guide provides consumers with information to help them determine whether a small wind electric system can provide all or a portion of the energy they need for their home or business based on their wind resource, energy needs, and their economics. Topics discussed in the guide include how to make a home more energy efficient, how to choose the correct turbine size, the parts of a wind electric system, how to determine whether enough wind resource exists, how to choose the best site for a turbine, how to connect a system to the utility grid, and whether it's possible to become independent of the utility grid using wind energy. In addition, the cover of the guide contains a regional wind resource map and a list of incentives and contacts for more information.
Date: May 1, 2004
Creator: unknown
Object Type: Text
System: The UNT Digital Library
Study and Development of Anti-Islanding Control for Grid-Connected Inverters (open access)

Study and Development of Anti-Islanding Control for Grid-Connected Inverters

This is a report on the development of anti-islanding control for grid-connected inverters from distributed generation sources. Islanding occurs when a distributed generation source continues to provide electricity to a portion of the utility grid after the utility experiences a disruption in service. Since the utility no longer controls this part of the distribution system, islanding can pose problems for utility personnel safety, power quality, equipment damage, and restoration of service. This report proposes a new family of anti-islanding schemes that meet IEEE 1547 interconnection standards, that can detect all disruptions in service, have minimum power-quality impact, require low-cost implementation, work for multiple distributed generators, and work for any multi-phase inverters. It also provides design guidelines for the schemes, and evaluates and validates the proposed schemes for practical applications.
Date: May 1, 2004
Creator: Ye, Z.; Walling, R.; Garces, L.; Zhou, R.; Li, L. & Wang, T.
Object Type: Report
System: The UNT Digital Library
Investigation of Gettering Mechanisms in Crystalline Silicon: Final Subcontract Report, 21 July 1997--30 September 2003 (open access)

Investigation of Gettering Mechanisms in Crystalline Silicon: Final Subcontract Report, 21 July 1997--30 September 2003

In this investigation, various aspects of the mechanisms of gettering contaminant impurities away from device active regions in Si have been systematically conducted. Also systematically studied are the modeling of electrical activity of metallic precipitates in Si based on the Schottky effect. With these studies, our knowledge of gettering in Si and on the electrical activity of metallic precipitates in Si has become substantially complete in the sense that interpretations of major experimental results have become self- and mutually consistent. The purpose of conducting the studies supported by this project was to obtain consistent interpretations of existing experimental results, as well as to conduct the needed new experiments, concerning the various phenomena associated with gettering in Si. The investigated gettering method is that by using an Al layer, and the involved works span from studies concerning basic point defect behaviors during gettering to studies of application of the gettering method to improve multicrystalline Si minority-carrier diffusion lengths. A preliminary study of the effect of gettering in affecting the solar cell efficiency has been conducted. Moreover, a study of the electrical behavior of precipitated metallic impurities in Si based on the Schottky property of the precipitates, which is a newly proposed …
Date: May 1, 2004
Creator: Tan, T. Y.
Object Type: Report
System: The UNT Digital Library
High Volume, Low Pressure Drop, Bioaerosol Collector Using a Multi-slit Virtual Impactor (open access)

High Volume, Low Pressure Drop, Bioaerosol Collector Using a Multi-slit Virtual Impactor

None
Date: May 18, 2004
Creator: Bergman, W; Shinn, J; Lochner, R; Sawyer, S; Milanovich, F & Jr, R M
Object Type: Article
System: The UNT Digital Library