A model was needed to assess material throughput and validate the conceptual design of a production facility, including equipment lists and layout. The initial desire was to use a commercially available discrete event simulation package. However, the available software was found to be too limited in capability. Database interface software was used to develop autonomous intelligent manufacturing workstations and material transporters. The initial Extend model used to assess material throughput and develop equipment lists for the preconceptual design effort was upgraded with software add-ons from Simulation Dynamics, Inc. (SDI). Use of the SDI database interface allowed the upgraded model to include: 1. a material mass balance at any level of detail required by the user, and 2. a transport system model that includes all transport system movements, time delays, and transfers between systems. This model will assist in evaluating transport system capacity, sensitive time delays in the system, and optimal operating strategies. An additional benefit of using the SDI database interface is dramatically improved run time performance. This allows significantly more runs to be completed to provide better statistics for overall plant performance. The model has all system and process parameters entered into sub-component accessible tables. All information for the …

Research program on the rheological properties of flowing suspensions. The primary purpose of the research supported by this grant was to study the flow characteristics of concentrated suspensions of non-colloidal solid particles and thereby construct a comprehensive and robust theoretical framework for modeling such systems quantitatively. At first glance, this seemed like a modest goal, not difficult to achieve, given that such suspensions were viewed simply as Newtonian fluids with an effective viscosity equal to the product of the viscosity of the suspending fluid times a function of the particle volume fraction. But thanks to the research findings of the Principal Investigator and of his Associates, made possible by the steady and continuous support which the PI received from the DOE Office of Basic Energy Sciences, the subject is now seen to be more complicated and therefore much more interesting in that concentrated suspensions have been shown to exhibit fascinating and unique rheological properties of their own that have no counterpart in flowing Newtonian or even non-Newtonian (polymeric) fluids. In fact, it is generally acknowledged that, as the result of these investigations for which the PI received the 2001 National Medal of Science, our understanding of how suspensions behave under …

We present the first data on e{sup +}e{sup -} pair production accompanied by nuclear breakup in ultra-peripheral gold-gold collisions at a center of mass energy of 200 GeV per nucleon pair. The nuclear breakup requirement selects events at small impact parameters, where higher-order corrections to the pair production cross section should be enhanced. We compare the pair kinematic distributions with two calculations: one based on the equivalent photon approximation, and the other using lowest-order quantum electrodynamics (QED); the latter includes the photon virtuality. The cross section, pair mass, rapidity and angular distributions are in good agreement with both calculations. The pair transverse momentum, p{sub T}, spectrum agrees with the QED calculation, but not with the equivalent photon approach. We set limits on higher-order contributions to the cross section. The e{sup +} and e{sup -} p{sub T} spectra are similar, with no evidence for interference effects due to higher-order diagrams.

The goal of this project was to develop catalytic materials and processes that would be effective in the destruction of tars formed during the gasification of black liquor and biomass. We report here the significant results obtained at the conclusion of this two year project.

The overall objective of this research is to delineate the process of the dilute-acid hydrolysis of biomass and seek better understanding of the reactions involving dilute-acid treatment of lignocellulosic biomass. Specifically the scope of the work entails the following two primary technical elements: Verification of the heterogeneous nature of the reaction mechanism in dilute-acid hydrolysis of cellulosic component of the biomass. Experimental investigation to identify the overall reaction pattern and the kinetic constants associated with dilute-acid hydrolysis of the cellulosic component of the agricultural residues.

In the process of Savannah River Site (SRS) operations limited amounts of waste are generated containing petroleum, and radiological contaminated soils. Currently, this combination of radiological and petroleum contaminated waste does not have an immediate disposal route and is being stored in low activity vaults. SRS developed and implemented a successful plan for clean up of the petroleum portion of the soils in situ using simple, inexpensive, bioreactor technology. Treatment in a bioreactor removes the petroleum contamination from the soil without spreading radiological contamination to the environment. This bioreactor uses the bioventing process and bioaugmentation or the addition of the select hydrocarbon degrading bacteria. Oxygen is usually the initial rate-limiting factor in the biodegradation of petroleum hydrocarbons. Using the bioventing process allowed control of the supply of nutrients and moisture based on petroleum contamination concentrations and soil type. The results of this work have proven to be a safe and cost-effective means of cleaning up low level radiological and petroleum-contaminated soil. Many of the other elements of the bioreactor design were developed or enhanced during the demonstration of a ''biopile'' to treat the soils beneath a Polish oil refinery's waste disposal lagoons. Aerobic microorganisms were isolated from the aged refinery's …

Cross sections have been measured for the {sup 107}Ag({alpha},{gamma}){sup 111}In reaction at several a-particle energies between 7.8 MeV and 11.9 MeV. This reaction is of interest because it can provide a check on calculations of low-energy ({alpha},{gamma}) cross sections required for stellar nucleosynthesis predictions. Stacks of natural Ag foils of 1 mm thickness and 99.97% purity were bombarded with {sup 4}He{sup +} beams. Following irradiation, the yields of the 171-keV and 245-keV photons produced in the 2.805 day electron-capture decay of the {sup 111}In product nucleus were measured off-line. The Ag foils were interleaved with 99.6% purity, 6 {micro}m thick natural Ti foils so that known cross sections for the {sup 48}Ti({alpha},n) reaction could be used to check the accuracy of the beam current integration. For any given beam energy, beam energy degradation in the foils resulted in lower effective bombarding energies for successive foils in the stack, enabling measurements to be made for several energies per irradiation. The measured cross sections are compared with published statistical-model calculations.

The authors present molecular dynamics simulation results for the viscosity and mutual diffusion constant of a strongly asymmetric two-component plasma (TCP). They compare the results with available theoretical models previously tested for much smaller asymmetries. for the case of viscosity they propose a new predictive framework based on the linear mixing rule, while for mutual diffusion they point out some consistency problems of widely used Boltzmann equation based models.

The most commonly discussed measures of microstructure in composite materials are the spatial correlation functions, which in a porous medium measure either the grain-to-grain correlations, or the pore-to-pore correlations in space. Improved bounds based on this information such as the Beran-Molyneux bounds for bulk modulus and the Beran bounds for conductivity are well-known. It is first shown here how to make direct use of this information to provide estimates that always lie between these upper and lower bounds for any microstructure whenever the microgeometry parameters are known. Then comparisons are made between these estimates, the bounds, and two new types of estimates. One new estimate for elastic constants makes use of the Peselnick-Meister bounds (based on Hashin-Shtrikman methods) for random polycrystals of laminates to generate self-consistent values that always lie between the bounds. A second new type of estimate for conductivity assumes that measurements of formation factors (of which there are at least two distinct types in porous media, associated respectively with pores and grains) are available, and computes new bounds based on this information. The paper compares and contrasts these various methods in order to clarify just what microstructural information and how precisely that information needs to be known …

The first fossil hominid tooth recovered during 1999 excavations from the Cisanca River region in West Java, Indonesia, was associated with a series of bovid teeth from a single individual that was recovered 190 cm beneath the hominid tooth. The age of the fossil bovid teeth was determined using electron paramagnetic resonance (EPR) analysis as part of an effort to bracket the age of the hominid tooth. The EPR-derived age of the bovid teeth is (5.16 {+-} 2.01) x 10{sup 5} years. However, the age estimate reported here is likely an underestimate of the actual age of deposition since evidence of heating was detected in the EPR spectra of the bovid teeth, and the heating may have caused a decrease in the intensity of EPR components on which the age calculation is based.

In a solid-state heat capacity laser (SSHCL), waste heat is stored in the lasing slabs, minimizing temperature gradients and optical distortions. After the maximum number of pulses is reached, the slabs are cooled or rapidly exchanged with cool slabs. During the past several years, our laboratory at LLNL has built a number of SSHCLs, demonstrating powers beyond 10 kW. In this paper, we model target interactions produced by a 10 kW device (500 J/pulse and 20 Hz), operating at a wavelength of 1.053 {micro}m. The laser contains 9 Nd:glass slabs pumped by flashlamps.

This document outlines a proposal for extending UPC's point-to-point memcpy library with support for explicitly non-blocking transfers, and non-contiguous (indexed and strided) transfers. Various portions of this proposal could stand alone as independent extensions to the UPC library. The designs presented here are heavily influenced by analogous functionality which exists in other parallel communication systems, such as MPI, ARMCI, Titanium, and network hardware API's such as Quadricselan, Infiniband vapi, IBM LAPI and Cray X-1. Each section contains proposed extensions to the libraries in the UPC Language Specification (section 7) and corresponding extensions to the GASNet communication system API.

A Full Aperture Backscatter Station (FABS) target diagnostic has been activated on the first four beams of the National Ignition Facility (NIF). Backscattered light from the target propagates back down the beam path into the FABS diagnostic system. FABS measures both stimulated Brillouin scattering (SBS) and stimulated Raman scattering (SRS) with a suite of measurement instruments. Digital cameras and spectrometers record spectrally resolved energy for both P and S polarized light. Streaked spectrometers measure the spectral and temporal behavior of the backscattered light. Calorimeters and fast photodetectors measure the integrated energy and temporal behavior of the light, respectively. This paper provides an overview of the FABS measurements system and detailed descriptions of the diagnostic instruments and the optical path.

Stable and radiocarbon isotope measurements made on CO{sub 2} from high temperature hydrothermal vents on the Endeavour Segment of the Juan de Fuca Ridge indicate both magmatic and sedimentary sources of carbon to the hydrothermal system. The Endeavour segment is devoid of overlying sediments and has shown no observable signs of surficial magmatic activity during the {approx}20 years of ongoing studies. The appearance of isotopically heavy, radiocarbon dead CO{sub 2} after a 1999 earthquake swarm requires that this earthquake event was magmatic in origin. Evidence for a sedimentary organic carbon source suggests the presence of buried sediments at the ridge axis. These findings, which represent the first temporally coherent set of radiocarbon measurements from hydrothermal vent fluids, demonstrate the utility of radiocarbon analysis in hydrothermal studies. The existence of a sediment source at Endeavour and the occurrence of magmatic episodes illustrate the extremely complex and evolving nature of the Endeavour hydrothermal system.

The effect of oxygenate molecular structure on soot emissions from a DI diesel engine was examined using carbon-14 ({sup 14}C) isotope tracing. Carbon atoms in three distinct chemical structures within the diesel oxygenate dibutyl maleate (DBM) were labeled with {sup 14}C. The {sup 14}C from the labeled DBM was then detected in engine-out particulate matter (PM), in-cylinder deposits, and CO{sub 2} emissions using accelerator mass spectrometry (AMS). The results indicate that molecular structure plays an important role in determining whether a specific carbon atom either does or does not form soot. Chemical-kinetic modeling results indicate that structures that produce CO{sub 2} directly from the fuel are less effective at reducing soot than structures that produce CO before producing CO{sub 2}. Because they can follow individual carbon atoms through a real combustion process, {sup 14}C isotope tracing studies help strengthen the connection between actual engine emissions and chemical-kinetic models of combustion and soot formation/oxidation processes.

GaAs Blocked-Impurity-Band (BIB) photoconductor detectors have the potential to become the most sensitive, low noise detectors in the far-infrared below 45.5 cm{sup -1} (220 {micro}m). We have studied the characteristics of liquid phase epitaxial GaAs films relevant to BIB production, including impurity band formation and the infrared absorption of the active section of the device. Knowledge of the far-infrared absorption spectrum as a function of donor concentration combined with variable temperature Hall effect and resistivity studies leads us to conclude that the optimal concentration for the absorbing layer of a GaAs BIB detector lies between 1 x 10{sup 15} and 6.7 x 10{sup 15} cm{sup -3}. At these concentrations there is significant wavefunction overlap which in turn leads to absorption beyond the 1s ground to 2p bound excited state transition of 35.5 cm{sup -1} (282 {micro}m). There still remains a gap between the upper edge of the donor band and the bottom of the conduction band, a necessity for proper BIB detector operation.

Achievement of atomic-resolution electron-beam tomography will allow determination of the three-dimensional structure of nanoparticles (and other suitable specimens) at atomic resolution. Three-dimensional reconstructions will yield ''section'' images that resolve atoms overlapped in normal electron microscope images (projections), resolving lighter atoms such as oxygen in the presence of heavier atoms, and atoms that lie on non-lattice sites such as those in non-periodic defect structures. Our first demonstrations of 3-D reconstruction to atomic resolution used five zone-axis images from test specimens of staurolite consisting of a mix of light and heavy atoms. We propose combining ultra-high (sub-Angstrom) resolution zone-axis images with off-zone images by first using linear reconstruction of the off-zone images while excluding images obtained within a small range of tilts (of the order of 60 milliradian) of any zone-axis orientation, since it has been shown that dynamical effects can be mitigated by slight off-axis tilt of the specimen. The (partial) reconstruction would then be used as a model for forward calculation by image simulation in zone-axis directions and the structure refined iteratively to achieve satisfactory fits with the experimental zone-axis data. Another path to atomic-resolution tomography would combine ''zone-axis tomography'' with high-resolution dark-field hollow-cone (DFHC) imaging. Electron diffraction theory indicates …

Models with low-scale breaking of global symmetries in the neutrino sector provide an alternative to the seesaw mechanism for understanding why neutrinos are light. Such models can easily incorporate light sterile neutrinos required by the LSND experiment. Furthermore, the constraints on the sterile neutrino properties from nucleosynthesis and large scale structure can be removed due to the non-conventional cosmological evolution of neutrino masses and densities. We present explicit, fully realistic supersymmetric models, and discuss the characteristic signatures predicted in the angular distributions of the cosmic microwave background.

Strong WW scattering at the LHC is discussed as a manifestation of electroweak symmetry breaking in the absence of a light Higgs bosom. The general framework of the Higgs mechanism--with or without a Higgs boson--is reviewed, and unitarity is shown to fix the scale of strong WW scattering. Strong WW scattering is also shown to be a possible outcome of five-dimensional models, which do not employ the usual Higgs mechanism at the TeV scale. Precision electroweak constraints are briefly discussed. Illustrative LHC signals are reviewed for models with QCD-like dynamics, stressing the complementarity of the W{sup {+-}}Z and like-charge W{sup +}W{sup +} + W{sup -}W{sup -} channels.

Grain size is a critically important aspect of polycrystalline materials and experimental observations on Cu and Al polycrystals have shown that a Hall-Petchtype phenomenon does exist at the onset of plastic deformation. In this work, a parametric study is conducted to investigate the effect of microstructural and deformation-related length scales on the behavior of such FCC polycrystals. It relies on a recently proposed non-local dislocation-mechanics based crystallographic theory to describe the evolution of dislocation mean spacings within each grain, and on finite element techniques to incorporate explicitly grain interaction effects. Polycrystals are modeled as representative volume elements (RVEs) containing up to 64 randomly oriented grains. Predictions obtained from RVEs of Cu polycrystals with different grain sizes are shown to be consistent with experimental data. Furthermore, mesh sensitivity studies revealed that, when there is a predominance of geometrically necessary dislocations (GNDs) relative to statistically-stored dislocations (SSDs), the polycrystal response becomes increasingly mesh sensitive. This was found to occur specially during the early stages of deformation in polycrystals with small grains.

One of the critical challenges facing planar solid oxide fuel cell (SOFC) technology is the need for reliable sealing technology. Seals are required for long-term stability and integrity in the high temperature SOFC environment during normal and transient operations. Several different approaches for sealing SOFC stacks are under development, including glass or glass-ceramic seals, metallic brazes, and compressive seals. Compressive seals potentially offer a significant and unique advantage over the other approaches by providing a means of mechanically ''de-coupling'' adjacent stack components, thereby minimizing the need for closely matching the coefficients of thermal expansion (CTE) of the various SOFC stack components. In an attempt to help the SOFC industry overcome sealing challenges, PNNL is developing mica-based hybrid compressive seals which exhibit leak rates 2 to 3 orders of magnitude lower than obtained with simple mica gasket seals.

A planar solid oxide fuel cell (SOFC) was fabricated using a tape-cast Ni/yttria-stabilized zirconia (YSZ) anode support, a YSZ thin film electrolyte, and a composite cathode of YSZ and (La{sub 0.85}Sr{sup 0.14}){sub 0.98}MnO{sub 3} (LSM). Using pure hydrogen as the fuel gas, a three cell stack with a cross-flow design and external manifolds produced peak power densities of 0.85 W/cm{sup 2} and 0.41 W/cm{sup 2} at 800 C and 700 C, respectively. Using wet methane as the fuel gas, the stack produced a peak power density of 0.22 W/cm{sup 2} at 700 C. Individual cells in the stack showed identical current-voltage (I -V) characteristics. Stack lifetime was limited because of degradation of the cells from oxidation products coming from the metallic interconnect used.

A set of experiments has been performed on the High-Current Experiment (HCX) facility at LBNL, in which the ion beam is allowed to collide with an end plate and thereby induce a copious supply of desorbed electrons. Through the use of combinations of biased and grounded electrodes positioned in between and downstream of the quadrupole magnets, the flow of electrons upstream into the magnets can be turned on or off. Properties of the resultant ion beam are measured under each condition. The experiment is modeled via a full three-dimensional, two species (electron and ion) particle simulation, as well as via reduced simulations (ions with appropriately chosen model electron cloud distributions, and a high-resolution simulation of the region adjacent to the end plate). The three-dimensional simulations are the first of their kind and the first to make use of a timestep-acceleration scheme that allows the electrons to be advanced with a timestep that is not small compared to the highest electron cyclotron period. The simulations reproduce qualitative aspects of the experiments, illustrate some unanticipated physical effects, and serve as an important demonstration of a developing simulation capability.

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