Publications

Abstract not provided.

Abstract not provided.

Abstract not provided.

Complex simulations (in particular, those involving multiple coupled physics) cannot be understood solely using geometry-based visualizations. Such visualizations are necessary in interpreting results and gaining insights into kinematics, however they are insufficient when striving to understand why or how something happened, or when investigating a simulation's dynamic evolution. For multiphysics simulations (e.g. those including solid dynamics with thermal conduction, magnetohydrodynamics, and radiation hydrodynamics) complex interactions between physics and material properties take place within the code which must be investigated in other ways. Drawing on the extensive previous work in view coordination, brushing and linking techniques, and powerful visualization libraries, we have developed Prism, an application targeted for a specific analytic need at Sandia National Laboratories. This multiview scientific visualization tool tightly integrates geometric and phase space views of simulation data and material models. Working closely with analysts, we have developed this production tool to promote understanding of complex, multiphysics simulations. We discuss the current implementation of Prism, along with specific examples of results obtained by using the tool.

Abstract not provided.

Abstract not provided.

Abstract not provided.

Economists, systems analysts, engineers, regulatory specialists, and other experts were assembled from academia, the national laboratories, and the energy industry to discuss present restoration practices (many have already been defined to the level of operational protocols) in the sectors of the energy infrastructure as well as other infrastructures, to identify whether economics, a discipline concerned with the allocation of scarce resources, is explicitly or implicitly a part of restoration strategies, and if there are novel economic techniques and solution methods that could be used help encourage the restoration of energy services more quickly than present practices or to restore service more efficiently from an economic perspective. AcknowledgementsDevelopment of this work into a coherent product with a useful message has occurred thanks to the thoughtful support of several individuals:Kenneth Friedman, Department of Energy, Office of Energy Assurance, provided the impetus for the work, as well as several suggestions and reminders of direction along the way. Funding from DOE/OEA was critical to the completion of this effort.Arnold Baker, Chief Economist, Sandia National Laboratories, and James Peerenboom, Director, Infrastructure Assurance Center, Argonne National Laboratory, provided valuable contacts that helped to populate the authoring team with the proper mix of economists, engineers, and systems and regulatory specialists to meet the objectives of the work.Several individuals provided valuable review of the document at various stages of completion, and provided suggestions that were valuable to the editing process. This list of reviewers includes Jeffrey Roark, Economist, Tennessee Valley Authority; James R. Dalrymple, Manager of Transmission System Services and Transmission/Power Supply, Tennessee Valley Authority; William Mampre, Vice President, EN Engineering; Kevin Degenstein, EN Engineering; and Patrick Wilgang, Department of Energy, Office of Energy Assurance.With many authors, creating a document with a single voice is a difficult task. Louise Maffitt, Senior Research Associate, Institute for Engineering Research and Applications at New Mexico Institute of Mining & Technology (on contract to Sandia National Laboratories) served a vital role in the development of this document by taking the unedited material (in structured format) and refining the basic language so as to make the flow of the document as close to a single voice as one could hope for. Louise's work made the job of reducing the content to a readable length an easier process. Additional editorial suggestions from the authors themselves, particularly from Sam Flaim, Steve Folga, and Doug Gotham, expedited this process.

Visualization in scientific computing refers to the process of transforming data produced by a simulation into graphical representations that help scientific users interpret the results. While the back-end rendering phase of this work can be performed efficiently in graphics card hardware, the front-end 'post processing' portion of visualization is currently performed entirely in software. Field-Programmable Gate Arrays (FPGAs) are an attractive option for accelerating post-processing operations because they enable users to offload computations into reconfigurable hardware. A key challenge in utilizing FPGAs for this work is developing an infrastructure that allows FPGAs to be integrated into a distributed visualization system. We propose a networked approach, where each post-processing FPGA is equipped with specialized network interface (NI) hardware that is capable of transporting graphics commands across the network to existing rendering resources. In this paper we discuss a NI for FPGAs that is comprised of a Chromium OpenGL interface, a TCP Offload Engine, and a Gigabit Ethernet module. A prototype system has been tested for a distributed isosurfacing application.

Abstract not provided.

Abstract not provided.

The Sandia Z accelerator has become a unique platform to study matter at extreme conditions. The large currents (20 MA, 200-300 ns rise time) and magnetic fields (several MG) produced by Z generate magnetic compression in the multi-Mbar regime, enabling quasi-isentropic compression experiments (ICE) to several Mbar stresses. Thus, the Z platform is useful in determining high stress material isentropes, performing phase transition studies (including rapid solidification), obtaining constitutive property information, and estimating material strength at high stress. Furthermore, the magnetic pressure can also accelerate macroscopic flyer plates to velocities in excess of 30 km/s. Thus, impact experiments can be performed to ultra-high pressures. Furthermore, the adiabatic release response of materials can be investigated through shock and release experiments, allowing hot, dense liquid states to be probed. The Z platform allows a large expanse of the equation of state surface to be explored enabling new and exciting material dynamics experiments. Specific examples from each of the areas mentioned above will be discussed.

Concerns about acts of terrorism against critical infrastructures have been on the rise for several years. Critical infrastructures are those physical structures and information systems (including cyber) essential to the minimum operations of the economy and government. The President's Commission on Critical Infrastructure Protection (PCCIP) probed the security of the nation's critical infrastructures. The PCCIP determined the water infrastructure is highly vulnerable to a range of potential attacks. In October 1997, the PCCIP proposed a public/private partnership between the federal government and private industry to improve the protection of the nation's critical infrastructures. In early 2000, the EPA partnered with the Awwa Research Foundation (AwwaRF) and Sandia National Laboratories to create the Risk Assessment Methodology for Water Utilities (RAM-W{trademark}). Soon thereafter, they initiated an effort to create a template and minimum requirements for water utility Emergency Response Plans (ERP). All public water utilities in the US serving populations greater than 3,300 are required to undertaken both a vulnerability assessment and the development of an emergency response plan. This paper explains the initial steps of RAM-W{trademark} and then demonstrates how the security risk assessment is fundamental to the ERP. During the development of RAM-W{trademark}, Sandia performed several security risk assessments at large metropolitan water utilities. As part of the scope of that effort, ERPs at each utility were reviewed to determine how well they addressed significant vulnerabilities uncovered during the risk assessment. The ERP will contain responses to other events as well (e.g. natural disasters) but should address all major findings in the security risk assessment.

This report summarizes progress from the Laboratory Directed Research and Development (LDRD) program during fiscal year 2004. In addition to a programmatic and financial overview, the report includes progress reports from 352 individual R and D projects in 15 categories. The 15 categories are: (1) Advanced Concepts; (2) Advanced Manufacturing; (3) Biotechnology; (4) Chemical and Earth Sciences; (5) Computational and Information Sciences; (6) Differentiating Technologies; (7) Electronics and Photonics; (8) Emerging Threats; (9) Energy and Critical Infrastructures; (10) Engineering Sciences; (11) Grand Challenges; (12) Materials Science and Technology; (13) Nonproliferation and Materials Control; (14) Pulsed Power and High Energy Density Sciences; and (15) Corporate Objectives.

Abstract not provided.

Abstract not provided.

Abstract not provided.

Abstract not provided.

Abstract not provided.

Abstract not provided.

Abstract not provided.

Abstract not provided.

Abstract not provided.

Experimental results [1] for the reflection coefficient of shock compressed xenon are compared with results from quantum molecular dynamics calculations with density functional theory (DFT). The real part of the optical conductivity is calculated within the Kubo-Greenwood formalism and the Kramers-Kroenig relations are used to generate the reflectivity and other optical properties. Improved agreement over non-ideal plasma theory [2] is found with the DFT calculations, but significant differences with the data remain. Since DFT in the various local density approximations tends to underestimate the band gap and overestimate the free electron population, we have used the ionizations from [2] to correct the DFT band gaps. This results in much improved agreement with the xenon reflectivity data and demonstrates a new approach to correcting DFT band gaps.

INVICE (INVerse analysis of Isentropic Compression Experiments) is a FORTRAN computer code that implements the inverse finite-difference method to analyze velocity data from isentropic compression experiments. This report gives a brief description of the methods used and the options available in the first beta version of the code, as well as instructions for using the code.

Abstract not provided.

Abstract not provided.

Abstract not provided.

Agile ready-when-needed patterning of refractive index structures in photosensitive materials requires an understanding of the impact of local application environment on mechanisms contributing to the desired photoinduced index change. The present work examines the impact of atmosphere on the photosensitive response of poly(methylphenylsilane) (PMPS) thin films whose high photoinduced index'change under low incident optical fluence make them attractive candidates for such applications. Changes in optical absorption and refractive index are investigated after exposure to ultraviolet (UV) light resonant with the lowest energy transition exhibited by the Si-Si backbone structure in the material. A comparison between photoinduced absorption changes for thin films exposed in an air atmosphere versus those observed for samples subjected to a nitrogen environment during photoexposure is made for the first time. The study reveals that the anaerobic conditions of the nitrogen atmosphere significantly reduce the photosensitive response of the material to light. These results are discussed in terms of photooxidation processes within the polysilane structure and in the context of the need for predictable photosensitive refractive index change in varied photoimprinting environments. © 2004 Elsevier B.V. All rights reserved.

Abstract not provided.

Abstract not provided.

Abstract not provided.

Abstract not provided.

Abstract not provided.

Abstract not provided.

Abstract not provided.

Metallic Phases in extraterrestrial materials are composed of Fe-Ni with minor amounts of Co, P, Si, Cr, etc. Electron microscopy techniques (SEM, TEM, EPMA, AEM) have been used for almost 50 years to study micron and submicron microscopic features in the metal phases (Fig. 1) such as clear taenite, cloudy zone, plessite, etc [1,2]. However lack of instrumentation to prepare TEM thin foils in specific sample locations and to obtain micro-scale crystallographic data have limited these investigations. New techniques such as the focused ion beam (FIB) and the electron backscatter electron diffraction (EBSD) techniques have overcome these limitations. The application of the FIB instrument has allowed us to prepare {approx}10 um long by {approx} 5um deep TEM thin sections of metal phases from specific regions of metal particles, in chondrites, irons and stony iron meteorites, identified by optical and SEM observation. Using a FEI dual beam FIB we were able to study very small metal particles in samples of CH chondrites [3] and zoneless plessite (ZP) in ordinary chondrites. Fig. 2 shows a SEM photomicrograph of a {approx}40 um ZP particle in Kernouve, a H6 chondrite. Fig. 3a,b shows a TEM photograph of a section of the FIB prepared TEM foil of the ZP particle and a Ni trace through a tetrataenite/kamacite region of the particle. It has been proposed that the Widmanstatten pattern in low P iron meteorites forms by martensite decomposition, via the reaction {gamma} {yields} {alpha}{sub 2} + {gamma} {yields} {alpha} + {gamma} in which {alpha}{sub 2}, martensite, decomposes to the equilibrium {alpha} and {gamma} phases during the cooling process [4]. In order to show if this mechanism for Widmanstatten pattern formation is correct, crystallographic information is needed from the {gamma} or taenite phases throughout a given meteorite. The EBSD technique was employed in this study to obtain the orientation of the taenite surrounding the initial martensite phase and the kamacite which forms as {alpha}{sub 2} or as Widmanstatten plates in a series of IVB irons. Fig. 4a,b shows EBSD orientation maps of taenite and kamacite from the Tawallah Valley IVB iron. We observe that the orientation of the taenite in the IVB meteorites is the same throughout the sample consistent with the orientation of the high temperature single phase taenite before formation of the Widmanstatten pattern.

Abstract not provided.

Abstract not provided.

The potential energy surface for the reaction between OH and acetylene has been calculated using the RQCISD(T) method and extrapolated to the complete basis-set limit. Rate coefficients were determined for a wide range of temperatures and pressures, based on this surface and the solution of the one-dimensional and two-dimensional master equations. With a small adjustment to the association energy barrier (1.1 kcal/mol), agreement with experiments is good, considering the discrepancies in such data. The rate coefficient for direct hydrogen abstraction is significantly smaller than that commonly used in combustion models. Also in contrast to previous models, ketene + H is found to be the main product at normal combustion conditions. At low temperatures and high pressures, stabilization of the C{sub 2}H{sub 2}OH adduct is the dominant process. Rate coefficient expressions for use in modeling are provided.

The National Spent Nuclear Fuel Program, located at the Idaho National Laboratory (INL), coordinates and integrates national efforts in management and disposal of US Department of Energy (DOE)-owned spent nuclear fuel. These management functions include development of standardised systems for long-term disposal in the proposed Yucca Mountain repository. Nuclear criticality control measures are needed in these systems to avoid restrictive fissile loading limits because of the enrichment and total quantity of fissile material in some types of the DOE spent nuclear fuel. This need is being addressed by development of corrosion-resistant, neutron-absorbing structural alloys for nuclear criticality control. This paper outlines results of a metallurgical development programme that is investigating the alloying of gadolinium into a nickel-chromium-molybdenum alloy matrix. Gadolinium has been chosen as the neutron absorption alloying element due to its high thermal neutron absorption cross section and low solubility in the expected repository environment. The nickel-chromium-molybdenum alloy family was chosen for its known corrosion performance, mechanical properties, and weldability. The workflow of this programme includes chemical composition definition, primary and secondary melting studies, ingot conversion processes, properties testing, and national consensus codes and standards work. The microstructural investigation of these alloys shows that the gadolinium addition is present in the alloy as a gadolinium-rich second phase. The mechanical strength values are similar to those expected for commercial Ni-Cr-Mo alloys. The alloys have been corrosion tested with acceptable results. The initial results of weldability tests have also been acceptable. Neutronic testing in a moderated critical array has generated favourable results. An American Society for Testing and Materials material specification has been issued for the alloy and a Code Case has been submitted to the American Society of Mechanical Engineers for code qualification.

Abstract not provided.

Wear is a critical factor in determining the durability of microelectromechanical systems (MEMS). While the reliability of polysilicon MEMS has received extensive attention, the mechanisms responsible for this failure mode at the microscale have yet to be conclusively determined. We have used on-chip polycrystalline silicon side-wall friction MEMS specimens to study active mechanisms during sliding wear in ambient air. Worn parts were examined by analytical scanning and transmission electron microscopy, while local temperature changes were monitored using advanced infrared microscopy. Observations show that small amorphous debris particles ({approx}50-100 nm) are removed by fracture through the silicon grains ({approx}500 nm) and are oxidized during this process. Agglomeration of such debris particles into larger clusters also occurs. Some of these debris particles/clusters create plowing tracks on the beam surface. A nano-crystalline surface layer ({approx}20-200 nm), with higher oxygen content, forms during wear at and below regions of the worn surface; its formation is likely aided by high local stresses. No evidence of dislocation plasticity or of extreme local temperature increases was found, ruling out the possibility of high temperature-assisted wear mechanisms.

Microanalysis is typically performed to analyze the near surface of materials. There are many instances where chemical information about the third spatial dimension is essential to the solution of materials analyses. The majority of 3D analyses however focus on limited spectral acquisition and/or analysis. For truly comprehensive 3D chemical characterization, 4D spectral images (a complete spectrum from each volume element of a region of a specimen) are needed. Furthermore, a robust statistical method is needed to extract the maximum amount of chemical information from that extremely large amount of data. In this paper, an example of the acquisition and multivariate statistical analysis of 4D (3-spatial and 1-spectral dimension) x-ray spectral images is described. The method of utilizing a single- or dual-beam FIB (w/o or w/SEM) to get at 3D chemistry has been described by others with respect to secondary-ion mass spectrometry. The basic methodology described in those works has been modified for comprehensive x-ray microanalysis in a dual-beam FIB/SEM (FEI Co. DB-235). In brief, the FIB is used to serially section a site-specific region of a sample and then the electron beam is rastered over the exposed surfaces with x-ray spectral images being acquired at each section. All this is performed without rotating or tilting the specimen between FIB cutting and SEM imaging/x-ray spectral image acquisition. The resultant 4D spectral image is then unfolded (number of volume elements by number of channels) and subjected to the same multivariate curve resolution (MCR) approach that has proven successful for the analysis of lower-dimension x-ray spectral images. The TSI data sets can be in excess of 4Gbytes. This problem has been overcome (for now) and images up to 6Gbytes have been analyzed in this work. The method for analyzing such large spectral images will be described in this presentation. A comprehensive 3D chemical analysis was performed on several corrosion specimens of Cu electroplated with various metals. Figure 1A shows the top view of the localized corrosion region prepared for FIB sectioning. The TSI region has been coated with Pt and a trench has been milled along the bottom edge of the region, exposing it to the electron beam as seen in Figure 1B. The TSI consisted of 25 sections and was approximately 6Gbytes. Figure 1C shows several of the components rendered in 3D: Green is Cu; blue is Pb; cyan represents one of the corrosion products that contains Cu, Zn, O, S, and C; and orange represents the other corrosion product with Zn, O, S and C. Figure 1 D shows all of the component spectral shapes from the analysis. There is severe pathological overlap of the spectra from Ni, Cu and Zn as well as Pb and S. in spite of this clean spectral shapes have been extracted from the TSI. This powerful TSI technique could be applied to other sectioning methods well.

Analyzing the performance of a complex System of Systems (SoS) requires a systems engineering approach. Many such SoS exist in the Military domain. Examples include the Army's next generation Future Combat Systems 'Unit of Action' or the Navy's Aircraft Carrier Battle Group. In the case of a Unit of Action, a system of combat vehicles, support vehicles and equipment are organized in an efficient configuration that minimizes logistics footprint while still maintaining the required performance characteristics (e.g., operational availability). In this context, systems engineering means developing a global model of the entire SoS and all component systems and interrelationships. This global model supports analyses that result in an understanding of the interdependencies and emergent behaviors of the SoS. Sandia National Laboratories will present a robust toolset that includes methodologies for developing a SoS model, defining state models and simulating a system of state models over time. This toolset is currently used to perform logistics supportability and performance assessments of the set of Future Combat Systems (FCS) for the U.S. Army's Program Manager Unit of Action.

Abstract not provided.

Abstract not provided.

Abstract not provided.

We design a density-functional-theory (DFT) exchange-correlation functional that enables an accurate treatment of systems with electronic surfaces. Surface-specific approximations for both exchange and correlation energies are developed. A subsystem functional approach is then used: an interpolation index combines the surface functional with a functional for interior regions. When the local density approximation is used in the interior, the result is a straightforward functional for use in self-consistent DFT. The functional is validated for two metals (Al, Pt) and one semiconductor (Si) by calculations of (i) established bulk properties (lattice constants and bulk moduli) and (ii) a property where surface effects exist (the vacancy formation energy). Good and coherent results indicate that this functional may serve well as a universal first choice for solid-state systems and that yet improved functionals can be constructed by this approach.

In this paper, we explore the stability properties of time-domain numerical methods for multitime partial differential equations (MPDEs) in detail. We demonstrate that simple techniques for numerical discretization can lead easily to instability. By investigating the underlying eigenstructure of several discretization techniques along different artificial time scales, we show that not all combinations of techniques are stable. We identify choices of discretization method and step size, along fast and slow time scales, that lead to robust, stable time-domain integration methods for the MPDE. One of our results is that applying overstable methods along one time-scale can compensate for unstable discretization along others. Our novel integration schemes bring robustness to time-domain MPDE solution methods, as we demonstrate with examples.