The nature of electronic excitations in crystalline solid nitromethane under conditions of shock loading and static compression are examined. Density functional theory calculations are used to determine the crystal bandgap under hydrostatic stress, uniaxial strain, and shear strain. Bandgap lowering under uniaxial strain due to molecular defects and vacancies is considered. In all cases, the bandgap is not lowered enough to produce a significant population of excited states in the crystal. Preliminary simulations on the formation of detonation product molecules from HMX are discussed.

Expression profiling and genomic DNA sequence comparisons are increasingly being applied to the identification and analysis of the genes involved in lipid metabolism. Not only has genome-wide expression profiling aided in the identification of novel genes involved in important processes in lipid metabolism such as sterol efflux, but the utilization of information from these studies has added to our understanding of the regulation of pathways participating in the process. Coupled with these gene expression studies, cross species comparison, searching for sequences conserved through evolution, has proven to be a powerful tool to identify important non-coding regulatory sequences as well as the discovery of novel genes relevant to lipid biology. An example of the value of this approach was the recent chance discovery of a new apolipoprotein gene (apo AV) that has dramatic effects upon triglyceride metabolism in mice and humans.

To facilitate the study of flux heterogeneity within a region, the authors have designed, built, and field-tested a highly portable, rapidly deployable, eddy covariance CO{sub 2} flux measurement system. The system is built from off-the-shelf parts and was assembled at a minimal cost. The unique combination of features of this system allow for a very rapid deployment with a minimal number of field personnel. The system is capable of making high precision, unattended measurements of turbulent CO{sub 2} fluxes, latent heat (LE) fluxes, sensible heat fluxes (H), and momentum transfer fluxes. In addition, many of the meteorological and ecosystem variables necessary for quality control of the fluxes and for running ecosystem models are measured. A side-by-side field comparison of the system at a pair of established AmeriFlux sites has verified that, for single measurements, the system is capable of CO{sub 2} flux accuracy of about {+-} 1.2 {micro}mole/m{sup 2}/sec, LE flux accuracy of about {+-} 15 Watts/m{sup 2}, H flux accuracy of about {+-} 7 Watts/m{sup 2}, and momentum transfer flux accuracy of about {+-} 11 gm-m/sec/sec. System deployment time is between 2 and 4 hours by a single person. The system was measured to draw between 30 and 35 …

The first irradiation experiment to evaluate the technical feasibility of proposed acitnide transmutation fuels for the US. Accelerator Transmutation of Waste program is currently under design. The goal of this irradiation experiment is to obtain initial irradiation performance data on candidate transmutation fuel concepts. The candidate fuels include non-fertile variations of (1) metallic alloys, (2) nitrides, (3) oxides, and (4) metal-matrix dispersion fuels. These fuels will be irradiated in the form of rodlets in the Advanced Test Reactor in Idaho beginning in September 2002. it is expected that postirradiation examinations will be performed on these fuels at the {approx} 7 and 20 at.-% burnup levels. This paper presents the design of the irradiation test vehicle and the fuel rodlets; the test matrix of fuel variations, the target test conditions; and the planned postirradiation examinations.

A recent increase in interest and development of wind energy in the Midwestern United States has focused the need for updating wind resource maps of this area. The wind resource assessment group at the National Renewable Energy Lab., a U.S. Department of Energy (DOE) laboratory, has produced updated high-resolution (1-km) wind resource maps for several states in this region. This abstract describes the computerized tools and methodology used by NREL to create the higher resolution maps.

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We report a method for making weld joints, capable of transmitting high supercurrent densities, in bulk samples of melt textured YBCO. The joining procedure is carried out in a flowing atmosphere of O{sub 2} to eliminate problems associated with nitrogen gas, which can become trapped in the joint. No filler or fluxing material is used. The method can be used to join large areas (several cm{sup 2}) that are capable of transmitting supercurrent densities exceeding 10{sup 4} A/cm{sup 2}.

Iron- and cobalt-exchanged ZSM-5 are active catalysts for the dissociation of nitrous oxide. In this study, density functional theory was used to assess a possible reaction pathway for the catalytic dissociation of N2O. The active center was taken to be mononuclear [FeO]+ or [CoO]+, and the surrounding portion of the zeolite was represented by a 24-atom cluster. The first step of N2O decomposition involves the formation of [FeO2]+ or [CoO2]+ and the release of N2. The metal-oxo species produced in this step then reacts with N2O again, to release N2 and O2. The apparent activation energies for N2O dissociation in Fe-ZSM-5 and Co-ZSM-5 are 39.4 and 34.6 kcal/mol, respectively. The preexponential factor for the apparent first-order rate coefficient is estimated to be of the order 107 s-1 Pa-1. While the calculated activation energy for Fe-ZSM-5 is in good agreement with that measured experimentally, the value of the preexponential factor is an order of magnitude smaller than that observed . The calculated activation energy for Co-ZSM-5 is higher than that reported experimentally. However, consistent with experiment, the rate of N2O decomposition on Co-ZSM-5 is predicted to be significantly higher than that on Fe-ZSM-5.

Prompt {gamma} rays from the neutron-induced fission of {sup 235}U have been studied using the GEANIE spectrometer situated at the LANSCE/WNR ''white'' neutron facility. Gamma-ray production cross sections for 29 ground-state-band transitions in 18 even-even fission fragments were obtained as a function of incident neutron energy, using the time-of-flight technique. Independent yields were deduced from these cross sections and fitted with standard formulations of the fragment charge and mass distributions to study the transition from asymmetric to symmetric fission. The results are interpreted in the context of the disappearance of shell structure at high excitation energies.

A newly proposed type of multicharged ion source offers the possibility of an economically advantageous high-charge-state fusion driver. Multiphoton absorption in an intense uniform laser focus can give multiple charge states of high purity, simplifying or eliminating the need for charge-state separation downstream. Very large currents (hundreds of amperes) can be extracted from this type of source. Several arrangements are possible. For example, the laser plasma could be tailored for storage in a magnetic bucket, with beam extracted from the bucket. A different approach, described in this report, is direct beam extraction from the expanding laser plasma. They discuss extraction and focusing for the particular case of a 4.1-MV beam of Xe{sup 16+} ions. The maximum duration of the beam pulse is limited by the total charge in the plasma, while the practical pulse length is determined by the range of plasma radii over which good beam optics can be achieved. The extraction electrode contains a solenoid for beam focusing. The design studies were carried out first with an envelope code and then with a self-consistent particle code. Results from the initial model showed that hundreds of amperes could be extracted, but that most of this current missed the solenoid …

The atmospheric dispersion of hazardous materials within the urban environment is a topic of great current interest. Urban structures have been shown/are known to cause overall slowing of the winds, channeling through street canyons, heat island phenomena, wake vortices and enhanced turbulence. Simulations that explicitly resolve individual buildings are limited by computational requirements to domains of a few kilometers. For models that simulate regions covering tens of kilometers with resolutions on the order of a kilometer, the effects of individual buildings must be parameterized by incorporating area-averaged canopy effects. For emergency response applications, results must be provided significantly faster than real time. ADAPT (Sugiyama and Chin, 1998) is a diagnostic model used by the Department of Energy's National Atmospheric Release Advisory Capability (NARAC) at Lawrence Livermore National Laboratory. It produces non-divergent wind, turbulence, and other meteorological fields required by the NARAC dispersion model LODI (Nasstrom et al., 2000). We have incorporated an urban parameterization into ADAPT for simulations with resolutions on the order of a kilometer. We have concentrated upon parameterizing what we believe are the most significant impacts of the urban canopy--the reduction of the mean velocity and the increased turbulence. The parameterization we have implemented is a modification …

An Intelligent Collection Environment for a data interpretation system is described. The environment accepts two inputs: A data model and a number between 0.0 and 1.0. The data model is as simple as a single word or as complex as a multi-level/multidimensional model. The number between 0.0 and 1.0 is a control knob to indicate the user's desire to allow loose matching of the data (things are ambiguous and unknown) versus strict matching of the data (things are precise and known). The environment produces a set of possible interpretations, a set of requirements to further strengthen or to differentiate a particular subset of the possible interpretation from the others, a set of inconsistencies, and a logic map that graphically shows the lines of reasoning used to derive the above output. The environment is comprised of a knowledge editor, model explorer, expertise server, and the World Wide Web. The Knowledge Editor is used by a subject matter expert to define Linguistic Types, Term Sets, detailed explanations, and dynamically created URI's, and to create rule bases using a straight forward hyper matrix representation. The Model Explorer allows rapid construction and browsing of multi-level models. A multi-level model is a model whose elements …

As part of a laser fusion diagnostic development program, we have performed pulsed neutron and pulsed laser tests of a CVD diamond detector manufactured from DIAFILM, a commercial grade of CVD diamond. The laser tests were performed at the short pulse UV laser at Bechtel Nevada in Livermore, CA. The pulsed neutrons were provided by DT capsule implosions at the OMEGA laser fusion facility in Rochester, NY. From these tests, we have determined the impulse response to be 250 ps fwhm for an applied E-field of 500 V/mm. Additionally, we have determined the sensitivity to be 2.8 mA/W at 500 V/mm and 4.5 mA/W at 1000 V/mm (2 to 6x times higher than reported values for natural Type IIa diamond). These detector characteristics allow us to conceive of a neutron time-of-flight current mode spectrometer based on CVD diamond. Such an instrument would sit inside the laser fusion target chamber close to TCC, and would record neutron spectra fast enough such that backscattered neutrons and y rays from the target chamber wall would not be a concern. However, the data we have taken show that the Electromagnetic Pulse (EMP) noise could be a limiting factor in performance. Determining the degree to …

This paper will present a survey of the current published work and products available to do off-line data mining for computer network security information. Hundreds of megabytes of data are collected every second that are of interest to computer security professionals. This data can answer questions ranging from the proactive, ''Which machines are the attackers going to try to compromise?'' to the reactive, ''When did the intruder break into my system and how?'' Unfortunately, there's so much data that computer security professionals don't have time to sort through it all. What we need are systems that perform data mining at various levels on this corpus of data in order to ease the burden of the human analyst. Such systems typically operate on log data produced by hosts, firewalls and intrusion detection systems as such data is typically in a standard, machine readable format and usually provides information that is most relevant to the security of the system. Systems that do this type of data mining for security information fall under the classification of intrusion detection systems. It is important to point out that we are not surveying real-time intrusion detection systems. Instead, we examined what is possible when the analysis …

Accelerator mass spectrometry (AMS) measured the relative contribution of ethanol to engine particulate matter (PM) from four ethanol-diesel blended fuels using contemporary grain alcohol as a tracer in low {sup 14}C diesel fuel. An emulsifier (Span 85) or cosolvent (butyl alcohol) facilitated mixing of the 12-25% ethanol blends. We operated the laboratory test engine, a 1993 Cummins B5.9 diesel, at a steady-state medium load and collected PM samples on pre-combusted quartz filters following dilution of engine exhaust in a mini-dilution tunnel. The ethanol blends emitted less PM and NOX than the control. The cosolvent blends reduced PM more effectively than the emulsified blends with similar oxygen content. The distribution of the oxygen, not just the quantity, was an important factor in reducing PM emissions. Any bio-derived fuel component is easily traced on the fossil background. Schemes for measuring volatile fractions of soot and gaseous emissions can be implemented.

We have investigated the flash of light that accompanies laser damage using time-resolved spectroscopy. Damage events were initiated in the bulk of both fused silica and DKDP crystals with 355-nm 3-ns pulsed radiation. Spectra from the accompanying flash were recorded in the 200-500 nm wavelength range with 5-ns temporal resolution. Ten ns following damage initiation, the spectra were found to be roughly blackbody with temperatures on the order of 5000 K to 7000 K, depending on the material studied and excitation energy used. The observed temperatures and cooling rates can be related to the size and electron density of the plasma ''fireball'' that initiates the damage event.

An important purpose of a programming language is to insulate the programmer from low level details and provide a high enough level of abstraction to be productive and develop reasonably portable application codes. For these reasons scientific programming is longer done using assembly language. But high performance of scientific applications often requires that critical sections of code be expressed at a particularly low level to avoid inefficiencies introduced by the comiler (function call overhead, poor cache use, etc.). The use of high-level abstractions exaserbates this problem since the compiler is often unable to generate the equivalent low-level code required for good performance. The result is often significantly degraded performance. Libraries provide a way for domain specific knowledge to be developed for large numbers of users. Libraries thus simplify the development of many application codes and the work spent building libraries can be amortized across large numbers of applications and application developers. Such a hierarchy puts languages and compilers at the root of tree of abstractsions developed within numerous libraries at one level and numerous applications at a second level. Libraries provide a way to define high-level abstractions. We have developed specific libraries to simplify the development of serial and parallel …

Geologic sequestration represents a promising strategy for isolating CO{sub 2} waste streams from the atmosphere. Successful implementation of this approach hinges on our ability to predict the relative effectiveness of subsurface CO{sub 2} migration and sequestration as a function of key target-formation and cap-rock properties, which will enable us to identify optimal sites and evaluate their long-term isolation performance. Quantifying this functional relationship requires a modeling capability that explicitly couples multiphase flow and kinetically controlled geochemical processes. We have developed a unique computational package that meets these criteria, and used it to model CO{sub 2} injection at Statoil's North-Sea Sleipner facility, the world's first saline-aquifer storage site. The package integrates a state-of-the-art reactive transport simulator (NUFT) with supporting geochemical software and databases (SUPCRT92). In our Sleipner study, we have quantified--for the first time--the influence of intra-aquifer shales and aquifer/cap-rock composition on migration/sequestration balance, sequestration partitioning among hydrodynamic, solubility, and mineral trapping mechanisms, and the isolation performance of shale cap rocks. Here, we review the fundamental elements of geologic CO{sub 2} sequestration in saline aquifers as revealed from model XSH of our Sleipner study; this model, unlike CSH and DSH, does not address the complicating (yet advantageous) presence of intra-aquifer shales.

The field of research into the optical properties of silicon nanostructures has seen enormous growth over the last decade. The discovery that silicon nanoparticles exhibit visible photoluminescence (PL) has led to new insights into the mechanisms responsible for such phenomena. The importance of understanding and controlling the PL properties of any silicon based material is of paramount interest to the optoelectronics industry where silicon nanoclusters could be embedded into existing silicon based circuitry. In this talk, we present a combination of quantum Monte Carlo and density functional approaches to the calculation of the electronic, structural, and optical properties of silicon nanostructures.

The control network for the National Ignition Facility (NIF) is designed to meet the needs for common object request broker architecture (CORBA) inter-process communication, multicast video transport, device triggering, and general TCP/IP communication within the NIF facility. The network will interconnect approximately 650 systems, including the embedded controllers, front-end processors (FEPs), supervisory systems, and centralized servers involved in operation of the NIF. All systems are networked with Ethernet to serve the majority of communication needs, and asynchronous transfer mode (ATM) is used to transport multicast video and synchronization triggers. CORBA software infra-structure provides location-independent communication services over TCP/IP between the application processes in the 15 supervisory and 300 FEP systems. Video images sampled from 500 video cameras at a 10-Hz frame rate will be multicast using direct ATM Application Programming Interface (API) communication from video FEPs to any selected operator console. The Ethernet and ATM control networks are used to broadcast two types of device triggers for last-second functions in a large number of FEPs, thus eliminating the need for a separate infrastructure for these functions. Analysis, design, modeling, and testing of the NIF network has been performed to provide confidence that the network design will meet NIF control requirements.

The Atmospheric Science Division at Lawrence Livermore National Laboratory uses the Naval Research Laboratory's Couple Ocean-Atmosphere Mesoscale Prediction System (COAMPS) for both operations and research. COAMPS is a non-hydrostatic model, designed as a multi-scale simulation system ranging from synoptic down to meso, storm and local terrain scales. As model resolution increases, the forcing due to small-scale complex terrain features including urban structures and surfaces, intensifies. An urban parameterization has been added to the Naval Research Laboratory's mesoscale model, COAMPS. The parameterization attempts to incorporate the effects of buildings and urban surfaces without explicitly resolving them, and includes modeling the mean flow to turbulence energy exchange, radiative transfer, the surface energy budget, and the addition of anthropogenic heat. The Chemical and Biological National Security Program's (CBNP) URBAN field experiment was designed to collect data to validate numerical models over a range of length and time scales. The experiment was conducted in Salt Lake City in October 2000. The scales ranged from circulation around single buildings to flow in the entire Salt Lake basin. Data from the field experiment includes tracer data as well as observations of mean and turbulence atmospheric parameters. Wind and turbulence predictions from COAMPS are used to drive …

In order to provide broader scientific recognition and to advance the science of shock compressed condensed matter, a group of American Physical Society (APS) members worked within the Society to make this field an active part of the APS. Individual papers were presented at APS meetings starting in the 1940's and shock wave sessions were organized starting with the 1967 Pasadena meeting. Shock wave topical conferences began in 1979 in Pullman, WA. Signatures were obtained on a petition in 1984 from a balanced cross-section of the shock wave community to form an APS Topical Group (TG). The APS Council officially accepted the formation of the Shock Compression of Condensed Matter (SCCM) TG at its October 1984 meeting. This action firmly aligned the shock wave field with a major physical science organization. Most early topical conferences were sanctioned by the APS while those held after 1992 were official APS meetings. The topical group organizes a shock wave topical conference in odd numbered years while participating in shock wavehigh pressure sessions at APS general meetings in even numbered years.