Using CARM (Computer Aided Reduction Method), a computer program that automates the mechanism reduction process, a variety of different reduced chemical kinetic mechanisms for ethylene and n-heptane have been generated. The reduced mechanisms have been compared to detailed chemistry calculations in simple homogeneous reactors and experiments. Reduced mechanisms for combustion of ethylene having as few as 10 species were found to give reasonable agreement with detailed chemistry over a range of stoichiometries and showed significant improvement over currently used global mechanisms. The performance of reduced mechanisms derived from a large detailed mechanism for n-heptane was compared to results from a reduced mechanism derived from a smaller semi-empirical mechanism. The semi-empirical mechanism was advantageous as a starting point for reduction for ignition delay, but not for PSR calculations. Reduced mechanisms with as few as 12 species gave excellent results for n-heptane/air PSR calculations but 16-25 or more species are needed to simulate n-heptane ignition delay.

Charge-coupled devices (CCD's) of novel design have been fabricated at Lawrence Berkeley National Laboratory (LBNL), and the first large-format science-grade chips for astronomical imaging are now being characterized at Lick Observatory. They are made on 300-μm thick n-type high-resistivity (~10,000 Ω-cm) silicon wafers, using a technology developed at LBNL to fabricate low-leakage silicon microstrip detectors for high-energy physics. A bias voltage applied via a transparent contact on the back side fully depletes the substrate, making the entire volume photosensitive and ensuring that charge reaches the potential wells with minimal lateral diffusion. The development of a thin, transparent back side contact compatible with fully depleted operation permits blue response comparable to that obtained with thinned CCD's. Since he entire region is active, high quantum efficiency is maintained to nearly λ = 1000 nm, above which the silicon bandgap effectively truncates photoproduction. Early characterization results indicate a charge transfer efficiency > 0.999995, readout noise 4 e's at -132°C, full well capacity > 300,000 e's, and quantum efficiency > 85% at λ = 900 nm.

The acceleration stages for a muon collider require that the muons be accelerated within a given ring in fewer than twenty turns. One type of accelerator that appears to be attractive for a synchrotron that accelerates the muon a factor of four in energy in a few turns is the Fixed Field Alternating Gradient (FFAG) type of accelerator. As the energy of the muon beam increases, the muons move toward a higher field region of a DC combined function dipole. The following dipole and quadrupole magnet characteristics are required for a muon FFAG machine to be successful: (1) The dipole will be a fixed field dipole with an impressed quadrupole and sextupole field. There may or may not be separate quadrupoles that mayor may not have added sextupole windings. (2) The horizontal aperture of the required good field region is wider than the vertical aperture of the required good field region. (3) The magnet is relatively short, so that the conventional SSC type of superconducting dipole or quadrupole ends can not be used. The field at the end of the magnet must fall off abruptly within the distance of less than one vertical aperture. For a magnet that is 400 …

XPS studies have been carried out on sputter deposited copper on a substantially hydroxylated {alpha}-Al{sub 2}O{sub 3}(0001) (sapphire) surface under ultra-high vacuum (UHV) conditions. XPS-derived Cu uptake curves show a sharp change in slope at a coverage of 0.35 monolayer (on a Cu/O atomic basis), indicative of initial layer-by-layer growth. CU(LMM) lineshape data indicate that, prior to the first break in the curve, Cu is oxidized to Cu(I). At higher coverages, metallic CU(0) is. observed. These data agree with first principles theoretical calculations, indicating that the presence of ad-hydroxyl groups greatly enhances the binding of Cu to bulk sapphire surfaces, stabilizing Cu(I) adatoms over two-dimensional metallic islands. In the absence of hydroxylation, calculations indicate significantly weaker Cu binding to the bulk sapphire substrate and non-wetting. Calculations also predict that at Cu coverages above 1/3 monolayer (ML), Cu-Cu interactions predominate, leading to Cu(0) formation. These results are in excellent agreement with experiment. The ability of surface hydroxyl groups to enhance binding to alumina substrates suggests a reason for contradictory experimental results reported in the literature for Cu wetting of alumina.

A spent fuel storage cask must efficiently transfer the heat released by the fuel assemblies through the cask walls to the environment. This heat must be transferred through passive means, limiting the energy transfer mechanisms from the cask to natural convection and radiation heat transfer.. Natural convection is essentially independent of the characteristics of the array of casks, provided there is space between casks to permit a convection loop. Radiation heat transfer, however, depends on the geometric arrangement of the array of casks because the peripheral casks will shadow the interior casks and restrict radiant heat transfer from all casks to the environment. The shadowing of one cask by its neighbors is determined by a view factor that represents the fraction of radiant energy that leaves the surface of a cask and reaches the environment. This paper addresses the evaluation of the view factor between a centrally located spent fuel storage cask and the environment. By combining analytic expressions for the view factor of (1) infinitely long cylinders and (2) finite cylinders with a length-to-diameter ratio of 2 to represent spent fuel storage casks, the view factor can be evaluated for any practical array of spent fuel storage casks.

Quartz crystal microbalance techniques and in situ spectroscopic ellipsometry are used to probe the structure-dependent intrinsic viscoelastic properties of self-assembled CH{sub 3}(CH{sub 2}){sub 8}SH alkanethiol monolayer adsorbed from the gas phase onto Au(111)-textured substrates. Physisorbed molecules, mixed chemisorbed-fluid/solid phases and solid-phase domain boundaries make sequentially dominant contributions to the measured energy dissipation in the growing monolayer. Deviations from Langmuir adsorption kinetics reveal a precursor-mediated adsorption channel. These studies reveal the impact of structural heterogeneity in tribological studies of monolayer lubricants.

The linear shaped charge is designed to produce a knife blade-like flat jet, which will perforate and sever one side of a modestly hard target from the other. This charge is approximately plane wave initiated and used a water pipe quality circular copper liner. To establish the quality of this jet we report about an experiment using several of the Lawrence Livermore National Laboratory high-resolution diagnostics previously published in this meeting [1]. Image converter tube camera stereo image pairs were obtained early in the jet formation process. Individual IC images were taken just after the perforation of a thin steel plate. These pictures are augmented with 70 mm format rotating mirror framing images, orthogonal 450 KeV flash radiograph pairs, and arrival time switches (velocity traps) positioned along the length of the jet edge. We have confirmed that linear shaped charges are subject to the same need for high quality copper as any other metal jetting device.

A feed-forward multilayer neural net is trained to learn the correspondence between seismic data and well logs. The introduction of a virtual input layer, connected to the nominal input layer through a special nonlinear transfer function, enables ultrafast (single iteration), near-optimal training of the net using numerical algebraic techniques. A unique computer code, named DeepNet, has been developed, that has achieved, in actual field demonstrations, results unattainable to date with industry standard tools.

Imaging through biologic tissue relies on the discrimination of weakly scattered from multiply scattered photons. The degree of polarization can be used as the discrimination criterion by which to reject multiply scattered photons. Polarized light propagation through biologic tissue is typically studied using tissue phantoms consisting of dilute aqueous suspensions of microsphere. We show that, although such phantoms are designed to match the macroscopic scattering properties of tissue (i.e.. the scattering coefficient, {mu}{sub 3}, and scattering anisotropy, g), they do not accurately represent biologic tissue for polarization-sensitive studies. In common tissue phantoms, such as dilute Intralipid and dilute 1-{micro}m-diameter polystyrene microsphere suspensions, we find that linearly polarized light is depolarized more quickly than circularly polarized light. In dense tissue, however, where scatterers are often located in close proximity to one another, circularly polarized light is depolarized similar to or more quickly than linearly polarized light. We also demonstrate that polarized light propagates differently in dilute versus densely packed microsphere suspensions, which may account for the differences seen between polarized light propagation in common dilute tissue phantoms versus dense biologic tissue.

Today, there are several drawbacks that impede the necessary and much needed use of robot learning techniques in real applications. First, the time needed to achieve the synthesis of any behavior is prohibitive. Second, the robot behavior during the learning phase is � by definition � bad, it may even be dangerous. Third, except within the lazy learning approach, a new behavior implies a new learning phase. We propose in this paper to use self-organizing maps to encode the non explicit model of the robot-world interaction sampled by the lazy memory, and then generate a robot behavior by means of situations to be achieved, i.e., points on the self-organizing maps. Any behavior can instantaneously be synthesized by the definition of a goal situation. Its performance will be minimal (not evidently bad) and will improve by the mere repetition of the behavior.

Lawrence Livermore National Laboratory in Livermore, California, is now performing significant astrophysics experiments on its huge Nova laser facility, and a similar effort has started at the Gekko laser facility at Osaka University in Japan. Our experiments on the Nova and Gekko lasers so far encourage us that our astrophysics work is already leading to a better understanding of the hydrodynamics of supernovae and astrophysical jets. The ability of large inertial confinement fusion lasers to recreate star-like conditions in the laboratory greatly improves our understanding of the heavens; for the first time in our history, we can study the stars up close on Earth.

There are currently two proposed standards for agent communication languages, namely, KQML (Finin, Lobrou, and Mayfield 1994) and the FIPA ACL. Neither standard has yet achieved primacy, and neither has been evaluated extensively in an open environment such as the Internet. It seems prudent therefore to design a general-purpose agent communications facility for new agent architectures that is flexible yet provides an architecture that accepts many different specializations. In this paper we exhibit the salient features of an agent communications architecture based on distributed metaobjects. This architecture captures design commitments at a metaobject level, leaving the base-level design and implementation up to the agent developer. The scope of the metamodel is broad enough to accommodate many different communication protocols, interaction protocols, and knowledge sharing regimes through extensions to the metaobject framework. We conclude that with a powerful distributed object substrate that supports metaobject communications, a general framework can be developed that will effectively enable different approaches to agent communications in the same agent system. We have implemented a KQML-based communications protocol and have several special-purpose interaction protocols under development.

Having laser intensities of 10{sup 21} W/cm{sup 2} yield electrical field strengths of 10{sup 12} V/cm which is comparable to the field strength at the K-shell of neon. Instant field ionization becomes part of the laser-matter interaction allowing to transfer most of the photons momenta directly onto the ions by driving an electrostatic shock through the target equivalent to pressures of several 100 Gbar. Utilization of these high-pressure conditions in form of equation of state measurements, however, strongly depends on the contrast of the femtosecond laser pulse. Currently, the Livermore USP and JanUSP lasers reach contrast values up to 10{sup 8}. This is sufficient to explore near-isochorically heated materials at moderate intensities (10{sup 13}-10{sup 15} W/cm{sup 2}) attaining pressures around 100 Mbar.

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There now exist close to 20 years of history in the application of Probabilistic Risk Assessment (PRA) for the analysis of fire risk at nuclear power plants. The current methods are based on various assumptions regarding fire phenomena, the impact of fire on equipment and operator response, and the overall progression of a fire event from initiation through final resolution. Over this same time period, a number of significant fire incidents have occurred at nuclear power plants around the world. Insights gained from US experience have been used in US studies as the statistical basis for establishing fire initiation frequencies both as a function of the plant area and the initiating fire source.To a lesser extent, the fire experience has also been used to assess the general severity and duration of fires. However, aside from these statistical analyses, the incidents have rarely been scrutinized in detail to verify the underlying assumptions of fire PRAs. This paper discusses an effort, under which a set of fire incidents are being reviewed in order to gain insights directly relevant to the methods, data, and assumptions that form the basis for current fire PRAs. The paper focuses on the objectives of the effort, the …

A new method is being developed to quickly screen for the human exposure potential to polycyclic aromatic hydrocarbons (PAHs) and organochlorines (OCs). The development involves two key elements: identifying suitable signals that represent intracellular changes that are specific to PAH and OC exposure, and constructing a device to guide the biological cell growth so that signals from individual cells are consistent and reproducible. We are completing the identification of suitable signals by using synchrotron radiation-based (SR) Fourier-transform infrared (FTIR) spectromicroscopy in the mid-infrared region (4000-400 cm-1). Distinct changes have been observed in the IR spectra after treatment of human cells in culture medium with PAHs and OCs. The potential use of this method for detecting exposure to PAHs and OCs has been tested and compared to a reverse transcription polymerase chain reaction (RT-PCR) assay that quantifies increased expression of the CYP1A1 gene in response to exposu re to PAHs or OCs.

The sensitivity of surface acoustic wave (SAW) sensors has been enhanced by increasing the active surface area of these devices. Electrodepositions of Ni, Pd, and Pt in a mass-transport-limited mode with trace foreign metals yield highly dendritic crystal structures of uniform macroscopic thickness. The concentration of metal ions, supporting electrolyte, agitation, and additives greatly impact the crystal morphology of the deposit. This methodology can be used simply and economically to provide high-area films in selective regions.

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Positron emission tomography (PET) studies mapping monoamine oxidase in the human brain have been used to measure the turnover rate for MAO B; to determine the minimum effective dose of a new MAO inhibitor drug lazabemide and to document MAO inhibition by cigarette smoke. These studies illustrate the power of PET and radiotracer chemistry to measure normal biochemical processes and to provide information on the effect of drug exposure on specific molecular targets.

The primary goals of this report are to (1) understand experimental radiography better (radiograph known static targets); and (2) to better understand the sources and effects of short wavelength perturbations on the long wavelength RT growth. Some secondary goals are to initiate Richtmyer-Meshkov mix targets; test beryllium cylinder implosions (if available); and observe emission spectroscopy from chlorinated foam to study implosions. To achieve these goals the authors: (1) shot mix targets with late backlighter and confirmed set up of radiography, begin static targets; (2) did a sequence of unperturbed and perturbed targets of different smoothness and thickness, fill in static, beryllium, and chlorinated foam targets; and (3) repeated step number 2 at a different backlighter time.

A long-standing conjecture in combinatorial optimization says that the integrality gap of the famous Held-Karp relaxation of the symmetric TSP is precisely 4/3. In this paper, we show that a slight strengthening of this conjecture implies a tight 4/3 integrality gap for a linear programming relaxation of the asymmetric TSP. This is surprising since no constant-factor approximation is known for the latter problem. Our main tools are a new characterization of the integrality gap for linear objective functions over polyhedra, and the isolation of ''hard-to-round'' solutions of the relaxations.

Development of isentropic loading techniques is a long standing goal of the shock physics community. The authors have used the Sandia Z Accelerator to produce smoothly increasing pressure loading on planar iron specimens over time durations of 100 ns and for pressures to 300 Mbar. Free surface velocity measurements on the rear surface of the continuously loaded specimens were made on specimens 0.5-mm and 0.8-mm thick and clearly show the effects of wave evolution into the well known two-wave structure resulting from the {alpha}-{var_epsilon} phase transition beginning at 125 kbar. The resulting wave profiles are analyzed with a rate-dependent, phase transition model to extract information on phase transformation kinetics for isentropic compression of iron. Comparison of the experiments and calculations demonstrate the value of isentropic loading for studying phase transition kinetics.

While nuclear safety analyses must always be conservative, invoking excessive conservatisms does not provide additional margins of safety. Rather, beyond a fairly narrow point, conservatisms skew a facility's true safety envelope by exaggerating risks and creating unreasonable bounds on what is required for safety. The conservatism has itself become unreasonable. A thorough review of the assumptions and methodologies contained in a facility's safety analysis can provide substantial reward, reducing both construction and operational costs without compromising actual safety.

Some recent theoretical results on coherent electromagnetic processes in ultrarelativistic heavy ion reactions are surveyed. In ultrarelativistic heavy ion collisions, Coulomb induced cross sections are huge, much larger than geometric. For the RHIC case of 100 GeV x 100 GeV colliding gold ions the predicted cross section for bound-electron positron pairs is about 110 barns. The corresponding cross section for continuum electron-positron pairs has recently been recalculated to be 34,000 barns, consistent with the result of the classic formula of Landau and Lifshitz. The cross section for Coulomb dissociation of the nucleus is about 95 barns, and the cross section for ionization of a single electron on one of the ions is about 100,000 barns.