AC Loss Measurements with a Cryocooled Sample (open access)

AC Loss Measurements with a Cryocooled Sample

A new cryostat cooled by a closed-cycle Cryomech GB-37 cryocooler for superconductor measurements at temperatures down to 20 K is described. The sample is conductively coupled to the cold stage so as to minimize vibration and thermal stresses. AC losses have been measured calorimetrically in several HTSC coils that have been wound to simulate sub-scale transformer winding pairs. Stable temperatures down to 20 K were reached on these coils, allowing measurements at practical levels of ac current and I{sub c}. By using short ac current pulses, losses on individual turns could be resolved. Results are reported mainly to showcase the apparatus, measurement procedure and analytical approach.
Date: February 15, 2001
Creator: Schwenterly, S.W.
System: The UNT Digital Library
Anti-Idling Laws and Regulations (open access)

Anti-Idling Laws and Regulations

None
Date: March 15, 2001
Creator: Levinson, Terry
System: The UNT Digital Library
Assessing Risk of Innovation (open access)

Assessing Risk of Innovation

Today's manufacturing systems and equipment must perform at levels thought impossible a decade ago. Companies must push operations, quality, and efficiencies to unprecedented levels while holding down costs. In this new economy, companies must be concerned with market shares, equity growth, market saturation, and profit. U.S. manufacturing is no exception and is a prime example of businesses forced to adapt to constant and rapid changes in customer needs and product mixes, giving rise to the term ''Agile Manufacturing''. The survival and ultimate success of the American Manufacturing economy may depend upon its ability to create, innovate, and quickly assess the impact that new innovations will have on its business practices. Given the need for flexibility, companies need proven methods to predict and measure the impact that new technologies and strategies will have on overall plant performance from an enterprise perspective. The Value-Derivative Model provides a methodology and approach to assess such impacts in terms of energy savings, production increases, quality impacts, emission reduction, and maintenance and operating costs as they relate to enabling and emerging technologies. This is realized by calculating a set of first order sensitivity parameters obtained from expanding a Taylor Series about the system's operating point. These …
Date: August 15, 2001
Creator: Allgood, GO
System: The UNT Digital Library
Automatic differentiation tools in optimization software. (open access)

Automatic differentiation tools in optimization software.

The authors discuss the role of automatic differentiation tools in optimization software. We emphasize issues that are important to large-scale optimization and that have proved useful in the installation of nonlinear solvers in the NEOS Server. Our discussion centers on the computation of the gradient and Hessian matrix for partially separable functions and shows that the gradient and Hessian matrix can be computed with guaranteed bounds in time and memory requirements.
Date: January 15, 2001
Creator: More, J. J.
System: The UNT Digital Library
CALORIMETRY FOR GLOBAL MEASUREMENTS IN PHENIX. (open access)

CALORIMETRY FOR GLOBAL MEASUREMENTS IN PHENIX.

The charged particle multiplicity, dN{sub ch}/d{eta}, and transverse energy, E{sub t}, are fundamental aspects of Heavy Ion collisions which PHENIX has measured in Au-Au collisions at a center-of-mass (c.m.s.) energy {radical}s{sub N}N = 130 GeV. E{sub t} is a multiparticle global observable related, through the Bjorken relation, to the maximum energy density achieved in the collision. For a given c.m.s. energy, the multiplicity and transverse energy are expected to increase with the number of nucleons participating in a collision (n{sub part}). The dependence on n{sub part} is found to be (dE{sub t}/d{eta}, dN{sub ch}/d{eta}) {approx} n{sub part}{sup {alpha}}, where {alpha} is larger than unity. This rapid growth (i.e. more rapid than linear) is not surprising in the collision of large nuclei since an individual participant nucleon may undergo more than one collision. The variable n{sub collision} is also introduced to denote the number of binary collisions. Whereas n{sub part} can be directly measured, in principle, directly from the number of non-participating nucleons detected in the forward direction, n{sub collision} is not observable but can be calculated statistically from n{sub part}, using the Glauber model.
Date: January 15, 2001
Creator: WHITE,S.N. FOR PHENIX COLLABORATION
System: The UNT Digital Library
CO{sub 2} injection for enhanced gas production and carbon sequestration (open access)

CO{sub 2} injection for enhanced gas production and carbon sequestration

Analyses suggest that carbon dioxide (CO{sub 2}) can be injected into depleted gas reservoirs to enhance methane (CH{sub 4}) recovery for periods on the order of 10 years, while simultaneously sequestering large amounts of CO{sub 2}. Simulations applicable to the Rio Vista Gas Field in California show that mixing between CO{sub 2} and CH{sub 4} is slow relative to repressurization, and that vertical density stratification favors enhanced gas recovery.
Date: November 15, 2001
Creator: Oldenburg, Curtis M. & Benson, Sally M.
System: The UNT Digital Library
Combining Semi-Classical and Quantum Mechanical Methodologies for Nuclear Cross-section Calculations Between 1 Mev and 5 Gev (open access)

Combining Semi-Classical and Quantum Mechanical Methodologies for Nuclear Cross-section Calculations Between 1 Mev and 5 Gev

With a goal to develop a nuclear cross-section code usable over the wide energy range of 1 MeV to 5 GeV, one option is to combine intranuclear cascade, pre-equilibrium, and Hauser-Feshbach models in existing codes. However, the first two models are semi-classical while the third one is quantum mechanical, and combining them is not straightforward because the third model requires spin and parity distributions for all excited states that cannot be supplied by either one of the first two models. Approximations to overcome this difficulty are described in this paper. Success of this combined model will allow nuclear data evaluations for a large number of materials whose cross sections are needed in a wide range of applications, including the design, operation, and future upgrades of the SNS (1 GeV proton). The incident particles may be neutrons, protons, charged pions, or photons. Though only partially completed at this time, the new model compares well with experimental radionuclide production cross sections from thresholds to 2.6 GeV for proton-induced reactions on Fe.
Date: August 15, 2001
Creator: Fu, C.Y.
System: The UNT Digital Library
Convalency of Neptunium(IV) Organometallics from {sup 237}Np Moessbauer Spectra (open access)

Convalency of Neptunium(IV) Organometallics from {sup 237}Np Moessbauer Spectra

The results of {sup 237}Np Moessbauer spectra provide a picture of the bonding of {sup 237}Np organometallics and their uranium analogues that could be obtained by no other method. In essence, Moessbauer results give a view of the compound from the position of the neptunium nucleus; the work summarized in this paper shows that the {sup 237}Np isomer shift results are consistent with available data and provide a useful picture of the bonding in actinide organometallics.
Date: March 15, 2001
Creator: Karraker, D.G.
System: The UNT Digital Library
Cooperative Robot Teams Applied to the Site Preparation Task (open access)

Cooperative Robot Teams Applied to the Site Preparation Task

Prior to human missions to Mars, infrastructures on Mars that support human survival must be prepared. robotic teams can assist in these advance preparations in a number of ways. This paper addresses one of these advance robotic team tasks--the site preparation task--by proposing a control structure that allows robot teams to cooperatively solve this aspect of infrastructure preparation. A key question in this context is determining how robots should make decisions on which aspect of the site preparation t6ask to address throughout the mission, especially while operating in rough terrains. This paper describes a control approach to solving this problem that is based upon the ALLIANCE architecture, combined with performance-based rough terrain navigation that addresses path planning and control of mobile robots in rough terrain environments. They present the site preparation task and the proposed cooperative control approach, followed by some of the results of the initial testing of various aspects of the system.
Date: June 15, 2001
Creator: Parker, LE
System: The UNT Digital Library
D0 calorimeter upgrades for Tevatron Run II (open access)

D0 calorimeter upgrades for Tevatron Run II

The electronic readout system for the D0 liquid argon calorimeter has been upgraded to take advantage of the upcoming Tevatron Run II. New scintillation preshower detectors have been installed as well as replacements for scintillation detectors in the intercryostat regions. These upgrades and preliminary testing and calibration results are described.
Date: August 15, 2001
Creator: Groer, Leslie S.
System: The UNT Digital Library
Design and implementation of the medium-beta insert of the Fermilab recycler ring (open access)

Design and implementation of the medium-beta insert of the Fermilab recycler ring

The design of the newly installed medium-{beta} insert of the Fermilab Recycler Ring is presented. The design philosophy is outlined. The stringent optical and physical constraints, as well as their influence on the design, are discussed. The impact of the medium-{beta} insert on the Recycler Ring is shown. Engineering design and installation of the new insert is presented.
Date: August 15, 2001
Creator: al., Weishi Wan et
System: The UNT Digital Library
Development and Test of World's First Industrial High-Temperature Superconducting (HTS) Power Cable (open access)

Development and Test of World's First Industrial High-Temperature Superconducting (HTS) Power Cable

Southwire Company has installed the world's first industrial high-temperature superconducting cable system to power three of its main manufacturing plants. The cable consists of three single-phase, 30-m long cables designed to carry 1250 A at 12.4 kV. The cable is cooled by a liquid nitrogen (LN) system that can supply LN at sub-cooled temperatures down to 72 K and at pressures up to 15 atmospheres. The design of the 30-m cables is based upon two 5-m cable prototypes, which were tested at a specially developed facility at ORNL. In addition to critical current and ac loss measurements, simulated fault-current tests were performed at ORNL on the 5-m cables. Cable terminations were designed to allow smooth transition from the cryogenic temperature and pressure environment of the HTS cable to ambient temperature and pressure for copper cables. A dielectric tape material, Cryoflex(trademark), was also developed for use at cryogenic temperatures.
Date: February 15, 2001
Creator: Sinha, U.K.
System: The UNT Digital Library
Does Incomputable Mean Not Engineerable? (open access)

Does Incomputable Mean Not Engineerable?

Self-referential systems have some remarkable properties. The processes of life and mind are not only self-referential, but self-reference turns out to be a crucial property of both. However, they are difficult to understand. From a given starting point, both endogenous systems (self-referential natural systems) and impredicative systems (self-referential formal systems) have infinitely many logically consistent consequences. Both are incomputable; neither halts after a finite number of steps. Therefore, neither can produce an exact prediction of the behavior of the other in finitely many steps. Despite the fact that all engineering decisions are based on incomplete information, this inherent inability of an impredicative model to produce exact predictions of an endogenous system is troubling to some engineers. Nevertheless, self-reference leads to a more general, but no less rational, form of modeling than that provided by traditional reductionism. Although the mathematics of self-reference is unfamiliar to engineers, its power is dramatic. For example, it resolves the apparent paradox of how a brain/mind possessing freewill can operate in a deterministic Universe.
Date: August 15, 2001
Creator: Kercel, Stephen W.
System: The UNT Digital Library
The Effect of Spatial Variability of Meteorological Data on Annual Average Air Concentrations Predicted by a Wind-Rose Model (open access)

The Effect of Spatial Variability of Meteorological Data on Annual Average Air Concentrations Predicted by a Wind-Rose Model

This paper discusses the effect of spatial variability of meteorological data on annual average air concentrations for distance from the source ranging from 2-21 km. Annual average relative air concentrations varied by about 20 percent for the stations examined. This study also showed that annual average concentrations obtained with a simple wind-rose model, although overpredicting by a factor of 3, are not particularly sensitive to the amount of meteorological data used to represent the frequency distribution of wind and stability. These results indicate that a much smaller data recovery rate than the 90 percent required by NRC might be more appropriate.
Date: March 15, 2001
Creator: Pendergast, M. M.
System: The UNT Digital Library
Electrochemical studies of the Mg2Si thin films prepared with pulsed laser deposition (open access)

Electrochemical studies of the Mg2Si thin films prepared with pulsed laser deposition

Electrochemically active thin films of Mg2Si (film thickness of 137 nm) have been prepared with the pulsed laser deposition technique. The film showed stable cycle behavior at 0.1 * 1.0 V vs Li with capacity greater than 800 mAh/g for more than 100 cycles. Though film morphology becomes remarkably rougher with cycling, this film showed continuous high stability in cycling. The capacity retention might be attributed to limited structural volume change in 2-dimensional film, easier lithium diffusion to film surface and enhanced conductivity supported from stainless steel substrate. The goal of this film study is to help clarify capacity failure of powder intermetallics alloy anodes.
Date: September 15, 2001
Creator: Song, Seung-Wan; Striebel, Kathryn & Cairns, Elton
System: The UNT Digital Library
Enhancement of dislocation velocities by stress assisted kink nucleation at the native oxide/SiGe interface (open access)

Enhancement of dislocation velocities by stress assisted kink nucleation at the native oxide/SiGe interface

Experiments have shown that the presence of a thin native oxide layer on the surface of a strained SiGe epilayer causes an order of magnitude increase in dislocation velocities during annealing over those observed in atomically clean samples and during crystal growth. This behavior is explained herein by stress-assisted dislocation kink nucleation at the oxide/epilayer interface. Finite element models are used to estimate the magnitude of stress local to steps at this interface due to both intrinsic and thermal expansion stresses, and dislocation theory is used to determine the resulting increase in single kink nucleation.
Date: February 15, 2001
Creator: Stach, E. A. & Hull, R.
System: The UNT Digital Library
ESCO market and industry trends: Updated results from the NAESCO database project (open access)

ESCO market and industry trends: Updated results from the NAESCO database project

Today's U.S. energy efficiency services industry is one of the most successful examples of private sector energy efficiency services in the world, yet little empirical information is available on the actual market activity of this industry. LBNL, together with the National Association of Energy Services Companies (NAESCO), has compiled the most comprehensive dataset of the energy efficiency services industry: nearly 1,500 case studies of energy efficiency projects. Our analysis of these projects helps shed light on some of the conventional wisdom regarding industry performance and evolution. We report key statistics about typical projects and industry trends that will aid state, federal, and international policymakers, and other investors interested in the development of a private sector energy efficiency services industry.
Date: October 15, 2001
Creator: Osborn, Julie G.; Goldman, Charles A. & Hopper, Nicole C.
System: The UNT Digital Library
Fabrication and test results of a high field, Nb3Sn superconducting racetrack dipole magnet (open access)

Fabrication and test results of a high field, Nb3Sn superconducting racetrack dipole magnet

The LBNL Superconducting Magnet Program is extending accelerator magnet technology to the highest possible fields. A 1 meter long, racetrack dipole magnet, utilizing state-of-the-art Nb{sub 3}Sn superconductor, has been built and tested. A record dipole filed of 14.7 Tesla has been achieved. Relevant features of the final assembly and tested results are discussed.
Date: June 15, 2001
Creator: Benjegerdes, R.; Bish, P.; Byford, D.; Caspi, S.; Dietderich, D.R.; Gourlay, S.A. et al.
System: The UNT Digital Library
FAST{_}AD Code Verification: A Comparison to ADAMS (open access)

FAST{_}AD Code Verification: A Comparison to ADAMS

The National Renewable Energy Laboratory's National Wind Technology Center (NWTC) has refocused its wind turbine design-code comparison effort to verify FAST{_}AD with ADAMS. FAST{_}AD is a wind turbine structural-response code developed by Oregon State University for the NWTC. ADAMS is a commercial, general-purpose, multibody-dynamics code developed by Mechanical Dynamics, Inc. ADAMS, which is used in many industries, has been rigorously tested. Both ADAMS and FAST{_}AD use the AeroDyn subroutine package for calculating aerodynamic forces. The University of Utah developed AeroDyn for the NWTC. To compare FAST{_}AD to ADAMS, we modeled a rough approximation of the AWT-27 P4 turbine, using the same properties for both simulators. The AWT-27 is a 275-kilowatt (kW), two-bladed wind turbine. We also created three-bladed versions of the turbine models to verify FAST{_}AD for three-bladed turbines. In this paper, we list the aerodynamic features used in the comparison. We also explain how the programs model the turbine structure, describe the degrees of freedom (DOFs) used for this study, and present simulation comparisons that show very good agreement.
Date: February 15, 2001
Creator: Buhl, M. L.; Wright, A. D. & Pierce, K. G.
System: The UNT Digital Library
First Results of Reaction Propagation Rates in HMX at High Pressure (open access)

First Results of Reaction Propagation Rates in HMX at High Pressure

The authors have measured the reaction propagation rate (RPR) in weapons-grade, ultrafine octahydro-1,3,57-tetranitro-1,3,5,7-tetrazocine (HMX) powder in a diamond anvil cell over the pressure range 0.7-35 GPa. In order to have a cross-comparison of their experiments, they carried out a series of experiments on nitromethane (NM) up to 15 GPa. The results on NM are indistinguishable from previous measurements of Rice and Folz. In comparison to high-pressure, NM, the burn process for solid HMX is not spatially uniform.
Date: June 15, 2001
Creator: Farber, D L; Esposito, A; Zaug, J M & Aracne-Ruddle, C
System: The UNT Digital Library
First Results of Reaction Propagation Rates in HMX at High Pressure (open access)

First Results of Reaction Propagation Rates in HMX at High Pressure

The authors have measured the reaction propagation rate (RPR) in weapons-grade, ultrafine octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX) powder in a diamond anvil cell over the pressure range 0.7-35 GPa. In order to have a cross-comparison of their experiments, they carried out a series of experiments on nitromethane (NM) up to 15 GPa. The results on NM are indistinguishable from previous measurements of Rice and Folz. In comparison to high-pressure NM, the burn process for solid HMX is between 5-10 times faster at pressures above 10 GPa.
Date: June 15, 2001
Creator: Farber, D L; Esposito, A; Zaug, J M & Aracne-Ruddle, C
System: The UNT Digital Library
Fracture Toughness Testing of ASTM A285 Steel for Fracture Analysis of Savannah River Site Storage Tanks (open access)

Fracture Toughness Testing of ASTM A285 Steel for Fracture Analysis of Savannah River Site Storage Tanks

The fracture toughness properties of A285 steels are being measured at specific material and test conditions for application to elastic-plastic fracture mechanics analysis of storage tanks at the Department of Energy Savannah River Site.
Date: May 15, 2001
Creator: Subramanian, K. H.
System: The UNT Digital Library
High flux compact neutron generators (open access)

High flux compact neutron generators

Compact high flux neutron generators are developed at the Lawrence Berkeley National Laboratory. The neutron production is based on D-D or D-T reaction. The deuterium or tritium ions are produced from plasma using either a 2 MHz or 13.56 MHz radio frequency (RF) discharge. RF-discharge yields high fraction of atomic species in the beam which enables higher neutron output. In the first tube design, the ion beam is formed using a multiple hole accelerator column. The beam is accelerated to energy of 80 keV by means of a three-electrode extraction system. The ion beam then impinges on a titanium target where either the 2.4 MeV D-D or 14 MeV D-T neutrons are generated. The MCNP computation code has predicted a neutron flux of {approximately}10{sup 11} n/s for the D-D reaction at beam intensity of 1.5 A at 150 kV. The neutron flux measurements of this tube design will be presented. Recently new compact high flux tubes are being developed which can be used for various applications. These tubes also utilize RF-discharge for plasma generation. The design of these tubes and the first measurements will be discussed in this presentation.
Date: June 15, 2001
Creator: Reijonen, J.; Lou, T. P.; Tolmachoff, B.; Leung, K. N.; Verbeke, J. & Vujic, J.
System: The UNT Digital Library
Impact of Air Leakage on the Thermal and Moisture Performance of the Building Envelope (open access)

Impact of Air Leakage on the Thermal and Moisture Performance of the Building Envelope

The air tightness of building envelopes systems is critical to the performance of a building. Uncontrolled airflow movements can cause moisture-induced damage by transporting large amounts of moisture, and may also impact occupant health and safety, sound control, fire control and energy efficiency. Building envelopes are often designed to control airflow by providing a resistance to the bulk flow. Implementation of air barrier systems to restrict airflow is commonly used to reduce the quantity of airflow movement between the exterior and interior environments through the wall. This paper presents a preliminary assessment of the influence of airflow on the moisture performance of a residential building envelope system. The combined heat, air and moisture (hygrothermal) transport in a selected wall is numerically investigated. Vapor diffusion, liquid transport and temperature dependent sorption isotherms are included in the investigation.
Date: August 15, 2001
Creator: Karagiozis, A
System: The UNT Digital Library