Towards a Sustainable Energy Balance: Progressive Efficiency and the Return of Energy Conservation (open access)

Towards a Sustainable Energy Balance: Progressive Efficiency and the Return of Energy Conservation

We argue that a primary focus on energy efficiency may not be sufficient to slow (and ultimately reverse) the growth in total energy consumption and carbon emissions. Instead, policy makers need to return to an earlier emphasis on"conservation," with energy efficiency seen as a means rather than an end in itself. We briefly review the concept of"intensive" versus"extensive" variables (i.e., energy efficiency versus energy consumption), and why attention to both consumption and efficiency is essential for effective policy in a carbon- and oil-constrained world with increasingly brittle energy markets. To start, energy indicators and policy evaluation metrics need to reflect energy consumption as well as efficiency. We introduce the concept of"progressive efficiency," with the expected or required level of efficiency varying as a function of house size, appliance capacity, or more generally, the scale of energy services. We propose introducing progressive efficiency criteria first in consumer information programs (including appliance labeling categories) and then in voluntary rating and recognition programs such as ENERGY STAR. As acceptance grows, the concept could be extended to utility rebates, tax incentives, and ultimately to mandatory codes and standards. For these and other programs, incorporating criteria for consumption as well as efficiency offers a path …
Date: August 13, 2007
Creator: Diamond, Rick; Harris, Jeff; Diamond, Rick; Iyer, Maithili; Payne, Christopher; Blumstein, Carl et al.
Object Type: Article
System: The UNT Digital Library
Toward Fast Computation of Dense Image Correspondence on the GPU (open access)

Toward Fast Computation of Dense Image Correspondence on the GPU

Large-scale video processing systems are needed to support human analysis of massive collections of image streams. Video, from both current small-format and future large-format camera systems, constitutes the single largest data source of the near future, dwarfing the output of all other data sources combined. A critical component to further advances in the processing and analysis of such video streams is the ability to register successive video frames into a common coordinate system at the pixel level. This capability enables further downstream processing, such as background/mover segmentation, 3D model extraction, and compression. We present here our recent work on computing these correspondences. We employ coarse-to-fine hierarchical approach, matching pixels from the domain of a source image to the domain of a target image at successively higher resolutions. Our diamond-style image hierarchy, with total pixel counts increasing by only a factor of two at each level, improves the prediction quality as we advance from level to level, and reduces potential grid artifacts in the results. We demonstrate the quality our approach on real aerial city imagery. We find that registration accuracy is generally on the order of one quarter of a pixel. We also benchmark the fundamental processing kernels on the …
Date: August 13, 2007
Creator: Duchaineau, M; Cohen, J & Vaidya, S
Object Type: Article
System: The UNT Digital Library
Soft X-ray Mirrors for the Linac Coherent Light Source (open access)

Soft X-ray Mirrors for the Linac Coherent Light Source

The Linac Coherent Light Source (LCLS) is a 0.15-1.5 nm wavelength free-electron laser (FEL) being constructed at the Stanford Linear Accelerator Center (SLAC) by a multi-institution consortium, including Lawrence Livermore National Laboratory (LLNL). One of LLNL's responsibilities involves the design and construction of two grazing-incidence mirror systems whose primary intent is to reduce radiation levels in the experimental halls by separating the FEL beam from unwanted high-energy photons. This paper discusses one of these systems, the Soft X-ray Offset Mirror System (SOMS) that will operate in the wavelength range 0.62-1.5 nm (0.827-2.00 keV). The unusual properties of the FEL beam translate to stringent specifications in terms of stability, material choice and mirror properties. It also precludes using approaches previously developed for synchrotron light sources. This situation has led us to a unique mirror design, consisting of a reflective boron carbide layer deposited on a silicon substrate. In the first part of this paper, we discuss the basic system requirements for the SOMS and motivate the need for these novel reflective elements. In the second part of this paper, we discuss the development work we have performed, including simulation and experimental verification of the boron carbide coating properties, and the expected …
Date: August 13, 2007
Creator: Pivovaroff, M. J.; Bionta, R. M.; Mccarville, T. J.; Soufli, R. & Stefan, P. M.
Object Type: Article
System: The UNT Digital Library
Editorial (open access)

Editorial

The Tenth International Conference on Accelerator Mass Spectrometry (AMS-10) was held from September 5-10 at the University of California, Berkeley campus. The conference attracted 305 attendees from 26 countries who gave 144 platform presentations and presented a total of 170 posters. The conference opened with a special tribute to the late Roy Middleton, which was followed by a companion session on 'ion sourcery'. A plenary talk by Wally Broecker on his '53 years in the Radiocarbon Trenches', provided thought-provoking challenges to commonly accepted paradigms. A workshop on issues in the estimation of isotopic ratios and evaluations of activities from AMS measurements preceded the conference and a workshop on AMS in low-dose bioscience concluded it. Conference attendees had ample opportunity to sample local sights and mid-week excursions to the Napa Valley wine region and the Monterey Bay Aquarium were well attended. The social highlight of the conference was a dinner cruise on San Francisco Bay aboard the San Francisco Belle, which toured the bay on a clear evening and afforded spectacular views of the city front as well as the Bay and Golden Gate bridges. The proceedings of AMS-10 contain 140 peer-reviewed papers that detail recent developments in AMS technology and …
Date: August 13, 2007
Creator: Knezovich, J; Brown, T; Buchholz, B; Finkel, B; Guilderson, T; Kashgarian, M et al.
Object Type: Article
System: The UNT Digital Library
Electrostatic Modeling of Vacuum Insulator Triple Junctions (open access)

Electrostatic Modeling of Vacuum Insulator Triple Junctions

A comprehensive matrix of 60 tests was designed to explore the effect of calcium chloride vs. sodium chloride and the ratio R of nitrate concentration over chloride concentration on the repassivation potential of Alloy 22. Tests were conducted using the cyclic potentiodynamic polarization (CPP) technique at 75 C and at 90 C. Results show that at a ratio R of 0.18 and higher nitrate was able to inhibit the crevice corrosion in Alloy 22 induced by chloride. Current results fail to show in a consistent way a different effect on the repassivation potential of Alloy 22 for calcium chloride solutions than for sodium chloride solutions.
Date: August 13, 2007
Creator: Tully, L. K.; White, A. D.; Goerz, D. A.; Javedani, J. B. & Houck, T. L.
Object Type: Article
System: The UNT Digital Library
A Study of Detonation Propagation and Diffraction with Compliant Confinement (open access)

A Study of Detonation Propagation and Diffraction with Compliant Confinement

A previous computational study of diffracting detonations with the ignition-and-growth model demonstrated that contrary to experimental observations, the computed solution did not exhibit dead zones. For a rigidly confined explosive it was found that while diffraction past a sharp corner did lead to a temporary separation of the lead shock from the reaction zone, the detonation re-established itself in due course and no pockets of unreacted material were left behind. The present investigation continues to focus on the potential for detonation failure within the ignition-and-growth (IG) model, but now for a compliant confinement of the explosive. The aim of the present paper is two fold. First, in order to compute solutions of the governing equations for multi-material reactive flow, a numerical method of solution is developed and discussed. The method is a Godunov-type, fractional-step scheme which incorporates an energy correction to suppress numerical oscillations that would occur near the material interface separating the reactive material and the inert confiner for standard conservative schemes. The numerical method uses adaptive mesh refinement (AMR) on overlapping grids, and the accuracy of solutions is well tested using a two-dimensional rate-stick problem for both strong and weak inert confinements. The second aim of the paper …
Date: August 13, 2007
Creator: Banks, J; Schwendeman, D; Kapila, A & Henshaw, W
Object Type: Article
System: The UNT Digital Library
Flux analysis of central metabolic pathways in the Fe(III)-reducing organism Geobacter metallireducens via 13C isotopiclabeling (open access)

Flux analysis of central metabolic pathways in the Fe(III)-reducing organism Geobacter metallireducens via 13C isotopiclabeling

We analyzed the carbon fluxes in the central metabolism ofGeobacter metallireducens strain GS-15 using 13C isotopomer modeling.Acetate labeled in the 1st or 2nd position was the sole carbon source,and Fe-NTA was the sole terminal electron acceptor. The measured labeledacetate uptake rate was 21 mmol/gdw/h in the exponential growth phase.The resulting isotope labeling pattern of amino acids allowed an accuratedetermination of the in vivo global metabolic reaction rates (fluxes)through the central metabolic pathways using a computational isotopomermodel. The model indicated that over 90 percent of the acetate wascompletely oxidized to CO2 via a complete tricarboxylic acid (TCA) cyclewhile reducing iron. Pyruvate carboxylase and phosphoenolpyruvatecarboxykinase were present under these conditions, but enzymes in theglyoxylate shunt and malic enzyme were absent. Gluconeogenesis and thepentose phosphate pathway were mainly employed for biosynthesis andaccounted for less than 3 percent of total carbon consumption. The modelalso indicated surprisingly high reversibility in the reaction betweenoxoglutarate and succinate. This step operates close to the thermodynamicequilibrium possibly because succinate is synthesized via a transferasereaction, and its product, acetyl-CoA, inhibits the conversion ofoxoglutarate to succinate. These findings enable a better understandingof the relationship between genome annotation and extant metabolicpathways in G. metallireducens.
Date: August 13, 2007
Creator: Tang, Yinjie J.; Chakraborty, Romy; Martin, Hector Garcia; Chu,Jeannie; Hazen, Terry C. & Keasling, Jay D.
Object Type: Article
System: The UNT Digital Library
MatProps: Material Properties Database and Associated Access Library (open access)

MatProps: Material Properties Database and Associated Access Library

Coefficients for analytic constitutive and equation of state models (EOS), which are used by many hydro codes at LLNL, are currently stored in a legacy material database (Steinberg, UCRL-MA-106349). Parameters for numerous materials are available through this database, and include Steinberg-Guinan and Steinberg-Lund constitutive models for metals, JWL equations of state for high explosives, and Mie-Gruniesen equations of state for metals. These constitutive models are used in most of the simulations done by ASC codes today at Livermore. Analytic EOSs are also still used, but have been superseded in many cases by tabular representations in LEOS (http://leos.llnl.gov). Numerous advanced constitutive models have been developed and implemented into ASC codes over the past 20 years. These newer models have more physics and better representations of material strength properties than their predecessors, and therefore more model coefficients. However, a material database of these coefficients is not readily available. Therefore incorporating these coefficients with those of the legacy models into a portable database that could be shared amongst codes would be most welcome. The goal of this paper is to describe the MatProp effort at LLNL to create such a database and associated access library that could be used by codes throughout the …
Date: August 13, 2007
Creator: Durrenberger, J K; Becker, R C; Goto, D M; Neely, J R & Wallin, B K
Object Type: Report
System: The UNT Digital Library
Final Report-Passive Safety Optimization in Liquid Sodium-Cooled Reactors. (open access)

Final Report-Passive Safety Optimization in Liquid Sodium-Cooled Reactors.

This report summarizes the results of a three-year collaboration between Argonne National Laboratory (ANL) and the Korea Atomic Energy Research Institute (KAERI) to identify and quantify the performance of innovative design features in metallic-fueled, sodium-cooled fast reactor designs. The objective of the work was to establish the reliability and safety margin enhancements provided by design innovations offering significant potential for construction, maintenance, and operating cost reductions. The project goal was accomplished with a combination of advanced model development (Task 1), analysis of innovative design and safety features (Tasks 2 and 3), and planning of key safety experiments (Task 4). Task 1--Computational Methods for Analysis of Passive Safety Design Features: An advanced three-dimensional subassembly thermal-hydraulic model was developed jointly and implemented in ANL and KAERI computer codes. The objective of the model development effort was to provide a high-accuracy capability to predict fuel, cladding, coolant, and structural temperatures in reactor fuel subassemblies, and thereby reduce the uncertainties associated with lower fidelity models previously used for safety and design analysis. The project included model formulation, implementation, and verification by application to available reactor tests performed at EBR-II. Task 2--Comparative Analysis and Evaluation of Innovative Design Features: Integrated safety assessments of innovative liquid …
Date: August 13, 2007
Creator: Cahalana, J. E. & Hahn, D.
Object Type: Report
System: The UNT Digital Library
Baseline Parameter Update for Human Health Input and Transfer Factors for Radiological Performance Assessments at the Savannah River Site (open access)

Baseline Parameter Update for Human Health Input and Transfer Factors for Radiological Performance Assessments at the Savannah River Site

The purpose of this report is to update parameters utilized in Human Health Exposure calculations and Bioaccummulation Transfer Factors utilized at SRS for Performance Assessment modeling.
Date: August 13, 2007
Creator: Coffield, T & Patricia Lee, P
Object Type: Report
System: The UNT Digital Library
HPC Colony: Linux at Large Node Counts (open access)

HPC Colony: Linux at Large Node Counts

None
Date: August 13, 2007
Creator: Jones, T; Tauferner, A; Inglett, T & Sidelnik, A
Object Type: Report
System: The UNT Digital Library
EFFECTS OF TRITIUM GAS EXPOSURE ON THE DYNAMIC MECHANICAL PROPERTIES OF EPDM ELASTOMER (open access)

EFFECTS OF TRITIUM GAS EXPOSURE ON THE DYNAMIC MECHANICAL PROPERTIES OF EPDM ELASTOMER

Samples of ethylene propylene diene monomer (EPDM) elastomer were exposed to tritium gas in closed containers initially at 101 kPa (1 atmosphere) pressure and ambient temperature for about one week. Tritium exposure effects on the samples were characterized by dynamic mechanical analysis (DMA) and radiolysis products were characterized by measuring the total final pressure and composition in the exposure containers at the end of exposure period. There was no effect of one week tritium exposure on the glass transition temperature, Tg, of the samples tested. Impurity gases produced in the closed containers included HT and lesser amounts of H{sub 2}, DTO, and CT{sub 4}. The total pressure remained the same during exposure.
Date: August 13, 2007
Creator: Clark, E & Gregory Staack, G
Object Type: Article
System: The UNT Digital Library
Sugar Policy and the 2007 Farm Bill (open access)

Sugar Policy and the 2007 Farm Bill

None
Date: August 13, 2007
Creator: unknown
Object Type: Report
System: The UNT Digital Library
Pushing the limits of plasma length scaling in inertial fusion laser-plasma interaction experiments (open access)

Pushing the limits of plasma length scaling in inertial fusion laser-plasma interaction experiments

None
Date: August 13, 2007
Creator: Froula, D; Divol, L; London, R; Michel, P; Berger, R L; Meezan, N B et al.
Object Type: Article
System: The UNT Digital Library
[Marine Dead Zones: Understanding the Problem, August 13, 2007] (open access)

[Marine Dead Zones: Understanding the Problem, August 13, 2007]

None
Date: August 13, 2007
Creator: Buck, Eugene H.
Object Type: Report
System: The UNT Digital Library