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Effective File I/O Bandwidth Benchmark

Description: The effective I/O bandwidth benchmark (b{_}eff{_}io) covers two goals: (1) to achieve a characteristic average number for the I/O bandwidth achievable with parallel MPI-I/O applications, and (2) to get detailed information about several access patterns and buffer lengths. The benchmark examines ''first write'', ''rewrite'' and ''read'' access, strided (individual and shared pointers) and segmented collective patterns on one file per application and non-collective access to one file per process. The number of parallel accessing processes is also varied and well-formed I/O is compared with non-well formed. On systems, meeting the rule that the total memory can be written to disk in 10 minutes, the benchmark should not need more than 15 minutes for a first pass of all patterns. The benchmark is designed analogously to the effective bandwidth benchmark for message passing (b{_}eff) that characterizes the message passing capabilities of a system in a few minutes. First results of the b{_}eff{_}io benchmark are given for IBM SP and Cray T3E systems and compared with existing benchmarks based on parallel Posix-I/O.
Date: February 15, 2000
Creator: Rabenseifner, R. & Koniges, A.E.
Partner: UNT Libraries Government Documents Department

WebDB Component Builder - Lessons Learned

Description: Oracle WebDB is the easiest way to produce web enabled lightweight and enterprise-centric applications. This concept from Oracle has tantalized our taste for simplistic web development by using a purely web based tool that lives nowhere else but in the database. The use of online wizards, templates, and query builders, which produces PL/SQL behind the curtains, can be used straight ''out of the box'' by both novice and seasoned developers. The topic of this presentation will introduce lessons learned by developing and deploying applications built using the WebDB Component Builder in conjunction with custom PL/SQL code to empower a hybrid application. There are two kinds of WebDB components: those that display data to end users via reporting, and those that let end users update data in the database via entry forms. The presentation will also discuss various methods within the Component Builder to enhance the applications pushed to the desktop. The demonstrated example is an application entitled HOME (Helping Other's More Effectively) that was built to manage a yearly United Way Campaign effort. Our task was to build an end to end application which could manage approximately 900 non-profit agencies, an average of 4,100 individual contributions, and $1.2 million dollars. Using WebDB, the shell of the application was put together in a matter of a few weeks. However, we did encounter some hurdles that WebDB, in it's stage of infancy (v2.0), could not solve for us directly. Together with custom PL/SQL, WebDB's Component Builder became a powerful tool that enabled us to produce a very flexible hybrid application.
Date: February 15, 2000
Creator: Macedo, C.
Partner: UNT Libraries Government Documents Department

Calibration Facilities for NIF

Description: The calibration facilities will be dynamic and will change to meet the needs of experiments. Small sources, such as the Manson Source should be available to everyone at any time. Carrying out experiments at Omega is providing ample opportunity for practice in pre-shot preparation. Hopefully, the needs that are demonstrated in these experiments will assure the development of (or keep in service) facilities at each of the laboratories that will be essential for in-house preparation for experiments at NIF.
Date: June 15, 2000
Creator: Perry, T. S.
Partner: UNT Libraries Government Documents Department

Canister Cleaning System Final Design Report Project A-2A

Description: Approximately 2,300 metric tons Spent Nuclear Fuel (SNF) are currently stored within two water filled pools, the 105 K East (KE) fuel storage basin and the 105 K West (KW) fuel storage basin, at the U.S. Department of Energy, Richland Operations Office (RL). The SNF Project is responsible for operation of the K Basins and for the materials within them. A subproject to the SNF Project is the Debris Removal Subproject, which is responsible for removal of empty canisters and lids from the basins. The Canister Cleaning System (CCS) is part of the Debris Removal Project. The CCS will be installed in the KW Basin and operated during the fuel removal activity. The KW Basin has approximately 3600 canisters that require removal from the basin. The CCS is being designed to ''clean'' empty fuel canisters and lids and package them for disposal to the Environmental Restoration Disposal Facility complex. The system will interface with the KW Basin and be located in the Dummy Elevator Pit.
Date: June 15, 2000
Creator: FARWICK, C.C.
Partner: UNT Libraries Government Documents Department

Evaluation of Multi Canister Overpack (MCO) Handling Machine Uplift Restraint for a Seismic Event During Repositioning Operations

Description: Insertion of the Multi-Canister Overpack (MCO) assemblies into the Canister Storage Building (CSB) storage tubes involves the use of the MCO Handling Machine (MHM). During MCO storage tube insertion operations, inadvertent movement of the MHM is prevented by engaging seismic restraints (''active restraints'') located adjacent to both the bridge and trolley wheels. During MHM repositioning operations, the active restraints are not engaged. When the active seismic restraints are not engaged, the only functioning seismic restraints are non-engageable (''passive'') wheel uplift restraints which function only if the wheel uplift is sufficient to close the nominal 0.5-inch gap at the uplift restraint interface. The MHM was designed and analyzed in accordance with ASME NOG-1-1995. The ALSTHOM seismic analysis reported seismic loads on the MHM uplift restraints and EDERER performed corresponding structural calculations to demonstrate structural adequacy of the seismic uplift restraint hardware. The ALSTHOM and EDERER calculations were performed for a parked MHM with the active seismic restraints engaged, resulting in uplift restraint loading only in the vertical direction. In support of development of the CSB Safety Analysis Report (SAR), an evaluation of the MHM seismic response was requested for the case where the active seismic restraints are not engaged. If a seismic event occurs during MHM repositioning operations, a moving contact at a seismic uplift restraint would introduce a friction load on the restraint in the direction of the movement. These potential horizontal friction loads on the uplift restraints were not included in the existing restraint hardware design calculations. One of the purposes of the current evaluation is to address the structural adequacy of the MHM seismic uplift restraints with the addition of the horizontal friction associated with MHM repositioning movements.
Date: May 15, 2000
Creator: SWENSON, C.E.
Partner: UNT Libraries Government Documents Department

Effect of Magnetic Geometry on ELM Heat Flux Profiles

Description: In this paper we explore how precisely the magnetic up/down symmetry must be controlled to insure sharing of edge localized mode (ELM) heat flux between upper and lower diverters in a double-null tokamak. We show for DIII-D, using infrared thermography, that the spatial distribution of Type-I ELM energy is less strongly affected by variations in magnetic geometry than is the time-averaged peak heat flux in attached discharges. The degree of control necessary to share ELM heat flux deposition equally between diverters was less stringent than the control needed to balance the time averaged heat flux. ELM energy is transported more than four times further into the scrape-off layer than the time-averaged heat flux.
Date: May 15, 2000
Creator: Lasnier, C.J.; Leonard, A.W.; Petrie, T.W. & Watkins, J.G.
Partner: UNT Libraries Government Documents Department

The ''Kinetic Stabilizer'': A Simpler Tandem Mirror Confinement?

Description: In the search for better approaches to magnetic fusion it is important to keep in mind the lessons learned in the 50 years that fusion plasma confinement has been studied. One of the lessons learned is that ''closed'' and ''open'' fusion devices differ fundamentally with respect to an important property of their confinement, as follows: Without known exception closed systems such as the tokamak, the stellarator, or the reversed-field pinch, have been found to have their confinement times limited by non-classical, i.e., turbulence-related, processes, leading to the requirement that such systems must be scaled-up in dimensions to sizes much larger than would be the case in the absence of turbulence. By contrast, from the earliest days of fusion research, it has been demonstrated that open magnetic systems of the mirror variety can achieve confinement times close to that associated with classical, i.e., collisional, processes. While these good results have been obtained in both axially symmetric fields and in non-axisymmetric fields, the clearest cases have been those in which the confining fields are solenoidal and axially symmetric. These observations, i.e., of confinement not enhanced by turbulence, can be traced theoretically to such factors as the absence of parallel currents in the plasma, and to the constraints on particle drifts imposed by the adiabatic invariants governing particle confinement in axisymmetric open systems. In the past the MHD instability of axially symmetric open systems has been seen as a barrier to their use. However, theory predicts MHD-stable confinement is achievable if sufficient plasma is present in the ''good curvature'' regions outside the mirrors. This theory has been confirmed by experiments on the Gas Dynamic Trap mirror-based experiment at Novosibirsk, In this paper a new way of exploiting this stabilizing principle, involving creating a localized ''stabilizer plasma'' outside a mirror, will be discussed. To ...
Date: June 15, 2000
Creator: Post, R.F.
Partner: UNT Libraries Government Documents Department

Stochastic Generator of Chemical Structure. 3. Reaction Network Generation

Description: A new method to generate chemical reaction network is proposed. The particularity of the method is that network generation and mechanism reduction are performed simultaneously using sampling techniques. Our method is tested for hydrocarbon thermal cracking. Results and theoretical arguments demonstrate that our method scales in polynomial time while other deterministic network generator scale in exponential time. This finding offers the possibility to investigate complex reacting systems such as those studied in petroleum refining and combustion.
Date: July 15, 2000
Creator: FAULON,JEAN-LOUP & SAULT,ALLEN G.
Partner: UNT Libraries Government Documents Department

Terrestrial photovoltaic technologies - Recent progress in manufacturing R&D

Description: This paper describes photovoltaics (PV) as used for energy generation in terrestrial applications. A brief historical perspective of PV development is provided. Solar-to-electricity conversion efficiencies for various photovoltaic materials are presented, as well as expectations for further material improvements. Recent progress in reducing manufacturing costs through process R&D and product improvements are described. Applications that are most suitable for the different technologies are discussed. Finally, manufacturing capacities and current and projected module manufacturing costs are presented.
Date: May 15, 2000
Creator: Witt, C. E.; Surek, T.; Mitchell, R. L.; Symko-Davies, M. & Thomas, H. P.
Partner: UNT Libraries Government Documents Department

GaAsSb/InGaAs type-II quantum wells for long-wavelength lasers on GaAs substrates

Description: The authors have investigated the properties of GaAsSb/InGaAs type-II bilayer quantum well structures grown by molecule beam epitaxy for use in long-wavelength lasers on GaAs substrates. Structures with layer, strains and thicknesses designed to be thermodynamically stable against dislocation formation exhibit room-temperature photoluminescence at wavelengths as long as 1.43 {mu}m. The photoluminescence emission wavelength is significantly affected by growth temperature and the sequence of layer growth (InGaAs/GaAsSb vs GaAsSb/InGaAs), suggesting that Sb and/or In segregation results in non-ideal interfaces under certain growth conditions. At low injection currents, double heterostructure lasers with GaAsSb/InGaAs bilayer quantum well active regions display electroluminescence at wavelengths comparable to those obtained in photoluminescence, but at higher currents the electroluminescence shifts to shorter wavelengths. Lasers have been obtained with threshold current densities as low as 120 A/cm{sup 2} at 1.17 {mu}m, and 2.1 kA/cm{sup 2} at 1.21 {mu}m.
Date: March 15, 2000
Creator: Klem, John F.; Spahn, Olga B.; Kurtz, Steven R.; Fritz, Ian J. & Choquette, Kent D.
Partner: UNT Libraries Government Documents Department

Die Soldering in Aluminium Die Casting

Description: Two types of tests, dipping tests and dip-coating tests were carried out on small steel cylinders using pure aluminum and 380 alloy to investigate the mechanism of die soldering during aluminum die casting. Optical and scanning electron microscopy were used to study the morphology and composition of the phases formed during soldering. A soldering mechanism is postulated based on experimental observations. A soldering critical temperature is postulated at which iron begins to react with aluminum to form an aluminum-rich liquid phase and solid intermetallic compounds. When the temperature at the die surface is higher than this critical temperature, the aluminum-rich phase is liquid and joins the die with the casting during the subsequent solidification. The paper discusses the mechanism of soldering for the case of pure aluminum and 380 alloy casting in a steel mold, the factors that promote soldering, and the strength of the bond formed when soldering occurs. conditions, an aluminum-rich soldering layer may also form over the intermetallic layer. Although a significant amount of research has been conducted on the nature of these intermetallics, little is known about the conditions under which soldering occurs.
Date: March 15, 2000
Creator: Han, Q.; Kenik, E.A. & Viswanathan, S.
Partner: UNT Libraries Government Documents Department

Some remarks on antenna response in a reverberation chamber

Description: The simple formula, {l_angle}P{sub r}{r_angle}=(E{sub o}{sup 2}/{eta})({lambda}{sup 2}/8{pi}), for the received power of an antenna with a matched load in an over-moded cavity actually holds for an antenna of any shape and size. This can be seen from the close connection between the correlation tensor of the cavity field at two different points and the imaginary part of the free-space dyadic Green's function.
Date: March 15, 2000
Creator: WARNE,LARRY K. & LEE,K.S.H.
Partner: UNT Libraries Government Documents Department

Stability characterizations of fixtured rigid bodies with Coulomb friction

Description: This paper formally introduces several stability characterizations of fixtured three-dimensional rigid bodies initially at rest and in unilateral contact with Coulomb friction. These characterizations, weak stability and strong stability, arise naturally from the dynamic model of the system, formulated as a complementarity problem. Using the tools of complementarity theory, these characterizations are studied in detail to understand their properties and to develop techniques to identify the stability classifications of general systems subjected to known external loads.
Date: February 15, 2000
Creator: PANG,J.S. & TRINKLE,JEFFREY C.
Partner: UNT Libraries Government Documents Department

Role of beam absorption in plasma during laser welding

Description: The relationship between beam focus position and penetration depth in CW laser welding was studied numerically and experimentally for different welding conditions. Calculations were performed using a transient hydrodynamic model that incorporates the effect of evaporation recoil pressure and the associated melt expulsion. The simulation results are compared with measurements made on a series of test welds obtained using a 1650 W CO{sub 2} laser. The simulations predict, and the experiments confirm, that maximum penetration occurs with a specific location of the beam focus, with respect to the original sample surface, and that this relationship depends on the processing conditions. In particular, beam absorption in the plasma has a significant effect on the relationship between penetration and focus position. When the process parameters result in strong beam absorption in the keyhole plasma, the maximum penetration will occur when the laser focus is at or above the sample surface. In a case of weak absorption however, the penetration depth reaches its maximum value when the beam focus is located below the sample surface. In all cases, the numerical results are in good agreement with the experimental measurements.
Date: May 15, 2000
Creator: SEMAK,V.V.; STEELE,R.J.; FUERSCHBACH,PHILLIP W. & DAMKROGER,BRIAN K.
Partner: UNT Libraries Government Documents Department

A novel manufacturing process for fabricating CdS/CdTe polycrystalline thin-film solar cells

Description: There are several production disadvantages inherent in conventional SnO{sub 2}/CdS/CdTe manufacturing processes. In this paper, the authors report a novel manufacturing process for fabricating polycrystalline Cd{sub 2}SnO{sub 4}/Zn{sub 2}SnO{sub 4}/CdS/CdTe thin-film solar cells that yielded a CdS/CdTe device with an NREL-confirmed efficiency of 14.0%. This process addresses undesirable manufacturing issues such as time-consuming and expensive heat-up and cool-down processes and generation of large amounts of liquid waste. CdTe cells prepared by this process have good performance, good uniformity, acceptable device stability, and excellent reproducibility.
Date: May 15, 2000
Creator: Wu, X. & Sheldon, P.
Partner: UNT Libraries Government Documents Department

Micromechanics of deformation in porous liquid phase sintered alumina under hertzian contact

Description: A series of fine-grained porous alumina samples, with and without a liquid phase, were fabricated in compositions matched closely to commercially available alumina used as a microelectronic substrates. Hertzian indentation on monolithic specimens of the glass-containing samples produced a greater quasi-ductile stress-strain response compared to that observed in the pure alumina. Maximum residual indentation depths, determined from surface profilometry, correlated with the stress-strain results. Moreover, microstructural observations from bonded interface specimens revealed significantly more damage in the form of microcracking and under extreme loading, pore collapse, in the glass-containing specimens. The absence of the typical twin faulting mechanism observed for larger-grained alumina suggests that the damage mechanism for quasi-ductility in these fine-grained porous alumina derived from the pores acting as a stress concentrator and the grain boundary glass phase providing a weak path for short crack propagation.
Date: May 15, 2000
Creator: DIGIOVANNI,ANTHONY A.; CHAN,HELEN M.; HARMER,MARTIN P. & NIED,HERMAN F.
Partner: UNT Libraries Government Documents Department

Beam emittance calculation in the presence of an axially symmetric magnetic field

Description: The Fermilab electron cooling project requires low transverse electron velocities (both coherent and incoherent) in the solenoidal cooling section. One of the possible reasons for an increase of these velocities is aberrations introduced by optical elements in the axially symmetric portion of the beam channel (first of all, in the acceleration tube) preceding the cooling section. Most of these optical elements can be treated as thin lenses so that the aberrations can be characterized by an increase of an effective beam emittance as a function of the beam radius in this element. The goal of this note is to formulate a method that would allow to correctly estimate these aberrations in the presence of linear coupling and a non-zero longitudinal magnetic field at the cathode. This is of particular interest for electron beam simulation programs that are employed to optimize beam transport in the presence of a varying longitudinal magnet field.
Date: May 15, 2000
Creator: Shemyakin, Sergei Nagaitsev and Alexander
Partner: UNT Libraries Government Documents Department

The effect of laser welding process parameters on the mechanical and microstructural properties of V-4Cr-4Ti structural materials.

Description: This paper reports on a systematic study which was conducted to examine the use of a pulsed Nd:YAG laser to weld sheet materials of V-Cr-Ti alloys and to characterize the microstructural and mechanical properties of the resulting joints. Deep penetration and defect-free welds were achieved under an optimal combination of laser parameters including focal length of lens, pulse energy, pulse repetition rate, beam travel speed, and shielding gas arrangement. The key for defect-free welds was found to be the stabilization of the keyhole and providing an escape path for the gas trapped in the weld. An innovative method was developed to obtain deep penetration and oxygen contamination free welds. Oxygen and nitrogen uptake were reduced to levels only a few ppm higher than the base metal by design and development of an environmental control box. Effort directed at developing an acceptable postwelding heat treatment showed that five passes of a diffuse laser beam over the welded region softened the weld material, especially in the root region of the weld.
Date: June 15, 2000
Creator: Reed, C.; Natesan, K.; Xu, Z. & Smith, D.
Partner: UNT Libraries Government Documents Department

Testing to support improvements to PV components and systems

Description: The National Photovoltaic (PV) Program is sponsored by the U.S. Department of Energy, and includes a PV Manufacturing Research and Development (R&D) project conducted with industry. This project includes advancements in PV components to improve reliability, reduce costs, and develop integrated PV systems. Participants submit prototypes, pre-production hardware products, and examples of the resulting final products for a range of tests conducted at several national laboratories, independent testing laboratories, and recognized listing agencies. The purpose of this testing is to use the results to assist industry in determining a product's performance and reliability, and to identify areas for potential improvement. This paper briefly describes the PV Manufacturing R&D project; participants in the area of PV systems, balance of systems, and components; and several examples of the different types of product and performance testing used to support and confirm product performance.
Date: May 15, 2000
Creator: Thomas, H., Kroposki, B.; Witt, C.; Bower, W.; Bonn, R.; Ginn, J. & Gonzales, S.
Partner: UNT Libraries Government Documents Department

Spectroscopy and lifetime of bottom and charm hadrons

Description: There are several motivations for studying masses and lifetimes of the hadrons containing a heavy quark, either the bottom or the charm quark. First, the mass and the lifetime are fundamental properties of an elementary particle. Second, the spectroscopy of hadrons gives insights into the QCD potential between quarks. In particular, a symmetry exists for heavy hadrons when the heavy quark mass is taken to be infinite, providing a powerful tool to predict and understand properties of those heavy hadrons. Third, studies of the lifetimes of heavy hadrons probe their decay mechanisms. A measurement of the lifetime, or the total decay width, is necessary when the authors extract magnitudes of elements of the Kobayashi-Maskawa matrix. Again, in the limit of an infinite heavy quark mass things become simple and decay of a heavy hadron should be the decay of the heavy quark Q. This leads to a prediction that all hadrons containing the heavy quark Q should have the same lifetime, that of the quark Q. This is far from reality in the case of charm hadrons, where the D{sup +} meson lifetime is about 2.5 times longer than the D{sup 0} meson lifetime. Perhaps the charm quark is not heavy enough. The simple quark decay picture should be a better approximation for the bottom hadrons because of the larger b quark mass. On the experimental side, the measurements and knowledge of the heavy hadrons (in particular bottom hadrons) have significantly improved over the last decade, thanks to high statistics data accumulated by various experiments. The authors shall review recent developments in these studies in the remainder of this manuscript.
Date: May 15, 2000
Creator: Ukegawa, F.
Partner: UNT Libraries Government Documents Department

Photovoltaics R and D: A tour through the 21st century

Description: The future investments for photovoltaics research and development are contemplated for this new millennium. Current technologies are used as the foundation for what might be expected for the next 50 years. A tour is conducted through what coming generations can anticipate for this technology; emphasizing non-conventional applications beyond the expected. Next-generation research approaches are predicted indicating the horizon of PV technology. Conjectures of those PV and related technologies that are beyond this horizon are presented, with prognosis what the coming generations might have as their conventional energy sources.
Date: May 15, 2000
Creator: Kazmerski, L. L.
Partner: UNT Libraries Government Documents Department

Analytical Chemistry Laboratory progress report for FY 1999

Description: This report summarizes the activities of the Analytical Chemistry Laboratory (ACL) at Argonne National Laboratory (ANL) for Fiscal Year (FY) 1999 (October 1998 through September 1999). This annual progress report, which is the sixteenth in this series for the ACL, describes effort on continuing projects, work on new projects, and contributions of the ACL staff to various programs at ANL.
Date: June 15, 2000
Creator: Green, D. W.; Boparai, A. S.; Bowers, D. L. & Graczyk, D. G.
Partner: UNT Libraries Government Documents Department