5,503 Matching Results

Search Results

Comparison of predicted far-field temperatures for discrete and smeared heat sources

Description: A fundamental concern in the design of the potential repository at Yucca Mountain. Nevada is the response of the host rock to the emplacement of heat-generating waste. The thermal perturbation of the rock mass has implications regarding the structural, hydrologic. and geochemical performance of the potential repository. The phenomenological coupling of many of these performance aspects makes repository thermal modeling a difficult task. For many of the more complex, coupled models, it is often necessary to reduce the geometry of the potential repository to a smeared heat-source approximation. Such simplifications have impacts on induced thermal profiles that in turn may influence other predicted responses through one- or two-way thermal couplings. The effect of waste employment layout on host-rock thermal was chosen as the primary emphasis of this study. Using a consistent set of modeling and input assumptions, far-field thermal response predictions made for discrete-source as well as plate source approximations of the repository geometry. Input values used in the simulations are consistent with a design-basis a real power density (APD) of 80 kW/acre as would be achieved assuming a 2010 emplacement start date, a levelized receipt schedule, and a limitation on available area as published in previous design studies. It was found that edge effects resulting from general repository layout have a significant influence on the shapes and extents of isothermal profiles, and should be accounted for in far-field modeling efforts.
Date: December 16, 1992
Creator: Ryder, E.E.
Partner: UNT Libraries Government Documents Department

Determination of coupled-lattice properties using turn-by-turn data

Description: A formalism for extracting coupled betatron parameters from multiturn, shock excited, beam position monitor data is described. The most important results are nonperturbative in that they do not rely on the underlying ideal lattice model. Except for damping, which is assumed to be exponential and small enough to be removed empirically, the description is symplectic. As well as simplifying the description, this leads to self-consistency checks that are applied to the data. The most important of these is a {open_quotes}magic ratio{close_quotes} of Fourier coefficients that is required to be a lattice invariant, the same at every beam position monitor. All formulas are applied to both real and simulated data. The real data was acquired June, 1992 at LEP as part of decoupling studies, using the LEP beam orbit measurement system. Simulated data, obtained by numerical tracking (TEAPOT) in the same (except for unknown errors) lattice, agrees well with real data when subjected to identical analysis. For both datasets, deviations between extracted and design parameters and deviations from self-consistency can be accounted for by noise and signal processing limitations. This investigation demonstrates that the LEP beam position system yields reliable local coupling measurements. It can be conservatively assumed that systems of similar design at the SSC and LHC will provide the measurements needed for local decoupling.
Date: December 1, 1992
Creator: Bourianoff, G.; Hunt, S. & Mathieson, D.
Partner: UNT Libraries Government Documents Department

SPECT reconstruction using a backpropagation neural network implemented on a massively parallel SIMD computer

Description: In this paper, the feasibility of reconstructing a single photon emission computed tomography (SPECT) image via the parallel implementation of a backpropagation neural network is shown. The MasPar, MP-1 is a single instruction multiple data (SIMD) massively parallel machine. It is composed of a 128 x 128 array of 4-bit processors. The neural network is distributed on the array by dedicating a processor to each node and each interconnection of the network. An 8 x 8 SPECT image slice section is projected into eight planes. It is shown that based on the projections, the neural network can produce the original SPECT slice image exactly. Likewise, when trained on two parallel slices, separated by one slice, the neural network is able to reproduce the center, untrained image to an RMS error of 0.001928.
Date: December 31, 1992
Creator: Kerr, J.P. & Bartlett, E.B.
Partner: UNT Libraries Government Documents Department

Vertex detectors

Description: The purpose of a vertex detector is to measure position and angles of charged particle tracks to sufficient precision so as to be able to separate tracks originating from decay vertices from those produced at the interaction vertex. Such measurements are interesting because they permit the detection of weakly decaying particles with lifetimes down to 10{sup {minus}13} s, among them the {tau} lepton and charm and beauty hadrons. These two lectures are intended to introduce the reader to the different techniques for the detection of secondary vertices that have been developed over the past decades. The first lecture includes a brief introduction to the methods used to detect secondary vertices and to estimate particle lifetimes. It describes the traditional technologies, based on photographic recording in emulsions and on film of bubble chambers, and introduces fast electronic registration of signals derived from scintillating fibers, drift chambers and gaseous micro-strip chambers. The second lecture is devoted to solid state detectors. It begins with a brief introduction into semiconductor devices, and then describes the application of large arrays of strip and pixel diodes for charged particle tracking. These lectures can only serve as an introduction the topic of vertex detectors. Time and space do not allow for an in-depth coverage of many of the interesting aspects of vertex detector design and operation.
Date: July 1, 1992
Creator: Lueth, V.
Partner: UNT Libraries Government Documents Department

The impact of thermal loading on repository performance at Yucca Mountain

Description: In the unsaturated zone at Yucca Mountain, liquid flow along preferential fracture pathways is the only credible mechanism capable of bringing water to waste packages and transporting radionuclide to the water table. Three categories of features or mechanisms will mitigate the impact of flow along preferential fracture pathways: (1) discontinuity in fracture pathways, (2) liquid-phase dispersion in fracture networks, and (3) fracture-matrix interaction. For repository areal power densities (APDs) that are too low to result in significant boiling or rock dry-out effects, the primary mode of fracture-matrix interaction is matrix imbibition. For high APDs, boiling and enhanced matrix imbibition due to rock dry-out significantly add to the capacity of the unsaturated zone to retard fracture-dominated flow. With the use of V-TOUGH code, hydrothermal flow calculations are made for a range of APDs and spent fuel ages. For APD > 20 kW/acre, repository-heat-generated flow of vapor and liquid in fractures is found to dominate the ambient hydrological system. For high APDs, boiling conditions can persist for 10,000 yr or longer and rock-dry benefits for at least 100,000 yr.
Date: January 15, 1992
Creator: Buscheck, T.A. & Nitao, J.J.
Partner: UNT Libraries Government Documents Department

Nonequilibrium molecular dynamics: The first 25 years

Description: Equilibrium Molecular Dynamics has been generalized to simulate Nonequilibrium systems by adding sources of thermodynamic heat and work. This generalization incorporates microscopic mechanical definitions of macroscopic thermodynamic and hydrodynamic variables, such as temperature and stress, and augments atomistic forces with special boundary, constraint, and driving forces capable of doing work on, and exchanging heat with, an otherwise Newtonian system. The underlying Lyapunov instability of these nonequilibrium equations of motion links microscopic time-reversible deterministic trajectories to macroscopic time-irreversible hydrodynamic behavior as described by the Second Law of Thermodynamics. Green-Kubo linear-response theory has been checked. Nonlinear plastic deformation, intense heat conduction, shockwave propagation, and nonequilibrium phase transformation have all been simulated. The nonequilibrium techniques, coupled with qualitative improvements in parallel computer hardware, are enabling simulations to approximate real-world microscale and nanoscale experiments.
Date: August 1, 1992
Creator: Hoover, W.G.
Partner: UNT Libraries Government Documents Department

Challenges and opportunities facing the international oil industry

Description: The report is divided into two sections. The first discusses the broad range of challenges facing the industry as it moves towards the 21st century. The author identifies four areas that present challenges: the quantity of oil; its quality; oil`s image; and the industry`s broader responsibilities. The second section looks at possible opportunities to meet these challenges: making the best use of the new world economic and political order; deriving the maximum benefit from a more unified international oil industry; and participating in environmental and other forms aimed at realigning the global energy mix.
Date: December 31, 1992
Partner: UNT Libraries Government Documents Department

Suppression of beam induced pulse shortening modes in high power RF generator TW output structures

Description: Several different style 11.4 GHz relativistic klystrons, operating with beam pulse widths of 50 ns and using large aperture, tapered phase-velocity TW structures,` have recently demonstrated output RF power levels in the range of 100 to 300 MW without breakdown or pulse shortening. To extend this performance into the long pulse regime (1 {mu}s) or to demonstrate a threefold increase in output power by using higher currents, the existing TW circuit designs must be modified (a) to reduce the cavity maximum surface E-fields by a factor of 2 to 3, and (b) to elevate the current threshold values of the beam induced higher order modes (HOM) to ensure avoidance of RF pulse shortening and associated instabilities. A technique for substantially elevating this threshold current is described, and microwave data and photographs are presented showing the degree of HOM damping achieved in a recently constructed 11.4 GHz TW structure.
Date: December 31, 1992
Creator: Haimson, J. & Mecklenburg, B.
Partner: UNT Libraries Government Documents Department

Temperature anisotropy and rotation upgrades to the ICRF modules in SNAP and TRANSP

Description: Fokker-Plank and transport codes have significantly better velocity-space treatment of the plasma than do the RF deposition models: FPP uses a 2 or 3D velocity space calculation, TRANSP uses Monte-Carlo particles, e.g., 3D in velocity space, many 2 and 3D spatial RF deposition codes are based on Maxwellians, with a single velocity-space parameter, i.e., the isotropic temperature. The ultimate goal of this effort was to provide the deposition codes with better velocity-space physics. For ICRH heating on TFTR, two important physics issues are velocity-space anisotropy (because of high energy tails), and plasma rotation (because of simultaneous NBI-RF heating). In addition, these two physical effects are among the suite of experimentally measurable quantities, and most of the required new formulas already exist in the literature.
Date: December 31, 1992
Creator: Smithe, D.N.
Partner: UNT Libraries Government Documents Department

A retrospective survey of the use of laboratory tests to simulate internal combustion engine materials tribology problems

Description: Progress in the Field of tribology strongly parallels, and has always been strongly driven by, developments and needs in transportation and related industries. Testing of candidate materials for internal combustion engine applications has historically taken several routes: (1) replacement of parts in actual engines subjected to daily use, (2) testing in special, instrumented test engines, (3) and simulative testing in laboratory tribometers using relatively simple specimens. The advantages and disadvantages of each approach are reviewed using historical examples. A four-decade, retrospective survey of the tribomaterials literature focused on the effectiveness of laboratory simulations for engine materials screening. Guidelines for designing and ducting successful tribology laboratory simulations will be discussed. These concepts were used to design a valve wear simulator at Oak Ridge National Laboratory.
Date: December 31, 1992
Creator: Blau, P.J.
Partner: UNT Libraries Government Documents Department

Low-level waste forum meeting reports

Description: This paper provides highlights from the spring meeting of the Low Level Radioactive Waste Forum. Topics of discussion included: state and compact reports; New York`s challenge to the constitutionality of the Low-Level Radioactive Waste Amendments Act of 1985; DOE technical assistance for 1993; interregional import/export agreements; Department of Transportation requirements; superfund liability; nonfuel bearing components; NRC residual radioactivity criteria.
Date: December 31, 1992
Partner: UNT Libraries Government Documents Department

Low-level waste forum meeting reports

Description: This report provides highlights from the 1992 fall meeting of the Low LEvel Radioactive Waste Forum. Topics included: disposal options after 1992; interregional agreements; management alternatives; policy; and storage.
Date: December 31, 1992
Partner: UNT Libraries Government Documents Department

Report on the Taos round table: Oil and money in the next decade

Description: This report summarizes the content of the conference held May 8--10, 1992 in Taos, Mexico. The conference explored the topic ``what is required from the world oil and gas community and what does it cost?`` The topics included areas of growth potential, changing demand patterns for refined product, and cost of pollution regulations. The conference then explored the requirements from the oil exploration and production sector, the requirements from the financial community and the priorities which should be set, and finally what strategy should be developed for survival growth and profitability in the next decade.
Date: December 31, 1992
Partner: UNT Libraries Government Documents Department

Regulatory policy issues and the Clean Air Act: An interim report on the state implementation workshops

Description: The National Regulatory Research Institute (NRRI), with funding from the U.S. Environmental Protection Agency (EPA) and U.S. Department of Energy (DOE), conducted two workshops on state public utility commission implementation of the Clean Air Act Amendments of 1990 (CAAA). The first workshop was held in Charlotte, North Carolina for southern and eastern states in April 1992 and the second was held in St. Louis, Missouri for Midwestern states in May. The workshops had four objectives: (1) discuss key issues and concerns on CAAA implementation, (2) encourage a discussion among states on issues of common interest, (3) attempt to reach consensus, where possible, on some key issues, and (4) provide the workshop participants with information and materials to assist in developing rules, orders, and procedures in their state. Of primary interest from the federal perspective was for workshop participants to return to their states with additional background and understanding of how state commission actions may affect implementation of the CAAA and enable them to provide guidance to their jurisdictional utilities. It was hoped this would reduce some of the uncertainty utilities face and assist in the development of an efficient allowance market. The basic format of the workshops was that invited speakers made presentations on specific issues. {open_quotes}Primary participants{close_quotes} from each state and other workshop attendees then discussed the issues raised by the speakers and other related concerns. The primary participants were state commissioners, commission staff, representatives from state consumer advocate organizations, EPA, DOE, and the Federal Energy Regulatory Commission (FERC). Other attendees were utility representatives, consultants, and other interested parties. All participants were given a workbook with excerpts from an NRRI report on CAAA implementation and papers or outlines from speakers.
Date: August 1, 1992
Creator: Rose, K. & Burns, R.E.
Partner: UNT Libraries Government Documents Department

Proceedings of the 1992 DOE/NREL hydrogen program review

Description: These proceedings contain 18 papers presented at the meeting. While the majority of the papers (11) had to do with specific hydrogen production methods, other papers were related to hydrogen storage systems, evaluations of and systems analysis for a hydrogen economy, and environmental transport of hydrogen from a pipeline leak.
Date: July 1, 1992
Creator: Rocheleau, R.E.; Gao, Q.H. & Miller, E.
Partner: UNT Libraries Government Documents Department

Measurements of barium photocathode quantum yields at four excimer laser wavelengths

Description: The electron quantum yields from barium cathodes excited by excimer laser radiation at 193, 248, 308, and 351 nm have been determined. Experiments with different cathode surface preparation techniques reveal that deposition of barium film a few microns thick on a clean copper surface under moderate vacuum conditions achieves relatively high quantum efficiencies. Quantum yields measured from surfaces prepared in this manner are 2.3 x 10{sup -3} at 193 nm, 7.6 x 10{sup - 4} at 248 nm, 6.1 x 10{sup -4} at 308 nm, and 4.0 x 10{sup -4} at 351 nm. Other preparation techniques, such as laser cleaning of a solid barium surface, produced quantum yields that were at least an order of magnitude lower than these values.
Date: June 1992
Creator: Van Loy, M. D.; Young, A. T. & Leung, K. N.
Partner: UNT Libraries Government Documents Department

Modeling the earth system

Description: The 1990 Global Change Institute (GCI) on Earth System Modeling is the third of a series organized by the Office for Interdisciplinary Earth Studies to look in depth at particular issues critical to developing a better understanding of the earth system. The 1990 GCI on Earth System Modeling was organized around three themes: defining critical gaps in the knowledge of the earth system, developing simplified working models, and validating comprehensive system models. This book is divided into three sections that reflect these themes. Each section begins with a set of background papers offering a brief tutorial on the subject, followed by working group reports developed during the institute. These reports summarize the joint ideas and recommendations of the participants and bring to bear the interdisciplinary perspective that imbued the institute. Since the conclusion of the 1990 Global Change Institute, research programs, nationally and internationally, have moved forward to implement a number of the recommendations made at the institute, and many of the participants have maintained collegial interactions to develop research projects addressing the needs identified during the two weeks in Snowmass.
Date: December 31, 1992
Creator: Ojima, D.
Partner: UNT Libraries Government Documents Department

Report on energy trends in the 90`s -- Implications for company strategies

Description: This report summarizes the content of the conference held on May 6--8, 1992, in Dallas, Texas. Three panel discussions were held on international issues and outlook: Emerging trends in Latin America; Update on the former Soviet Union; and Balancing world energy markets. The sessions on company strategies and perspectives included presentations by Enserch Corp., Union Pacific Resources, Union Texas Petroleum Holdings, Inc., and Triton Energy Corp. These sessions included the current position of the company, problems with development of specific fields, sharing the risks of exploratory drilling, commitment to domestic exploration, and international ventures in exploration.
Date: December 31, 1992
Partner: UNT Libraries Government Documents Department

The data base of the standards and related cross sections after ENDF/B-VI

Description: A brief description is given of the procedure used in the global evaluation of the standards and other important cross sections for ENDF/B-VI. The standards involved were {sup 6}Li(n,t), {sup 10}B(n,{alpha}{sub 1}), {sup 197}Au(n,{gamma}), and {sup 235}U(n,f). Other standards evaluated independently were H(n,p), {sup 3}He(n,p), C(n,f). The other cross sections involved were {sup 238}U(n,{gamma}), {sup 238}U(n,f), and {sup 239}Pu(n,f). The results of the evaluation are compared with new or revised experimental data which have become available after the completion of ENDF/B-VI. Overall good agreement is found, but a few problems are indicated by the new data.
Date: December 31, 1992
Creator: Poenitz, W.P. & Carlson, A.D.
Partner: UNT Libraries Government Documents Department

DOE UST interim subsurface barrier technologies workshop

Description: This document contains information which was presented at a workshop regarding interim subsurface barrier technologies that could be used for underground storage tanks, particularly the tank 241-C-106 at the Hanford Reservation.
Date: September 1, 1992
Partner: UNT Libraries Government Documents Department

Electroproduction of light quark baryons

Description: The status of electromagnetic excitation of light quark (u, d) baryon states is reviewed and confronted with results of calculations within the framework of microscopic models of the baryon structure and the photon - baryon coupling. Prospects for a qualitative improvement of their knowledge in this sector using photon and electron beams at the new, intermediate energy continuous wave (CW) electron machines are discussed.
Date: April 1, 1992
Creator: Burkert, V.
Partner: UNT Libraries Government Documents Department