We have developed cermet membranes that nongalvanically separate hydrogen from gas mixtures. The highest measured hydrogen flux was 16.2 cm{sup 3} (STP)/min-cm{sup 2} for an ANL-3a membrane at 900 C. For ANL-3 membranes with thickness of 0.04-0.5 mm, permeation rate is limited by the bulk diffusion of hydrogen through the metal phase. The effect of hydrogen partial pressure on permeation rate confirmed this conclusion and suggested that higher permeation rates may be obtained by decreasing the membrane thickness. Permeation rate in a syngas atmosphere for times up to 190 h showed no degradation in performance, which indicates that ANL-3 may be suitable for long-term, practical hydrogen separation.

With the advent of a rapidly proliferating international computer network, it became feasible to consider remote operation of instrumentation normally operated locally. For modern electron microscopes, the growing automation and computer control of many instrumental operations facilitated the task of providing remote operation. In order to provide use of NCEM TEMs by distant users, a project was instituted in 1995 to place a unique instrument, a Kratos EM-1500 operating at 1.5MeV, on-line for remote use. In 1996, the Materials Microcharacterization Collaboratory (MMC) was created as a pilot project within the US Department of Energy's DOE2000 program to establish national collaboratories to provide access via the Internet to unique or expensive DOE research facilities as well as to expertise for remote collaboration, experimentation, production, software development, modeling, and measurement. A major LBNL contribution to the MMC was construction of DeepView, a microscope-independent computer-control system that could be ported to other MMC members to provide a common graphical user-interface (GUI) for control of any MMC instrument over the wide area network.

A sacrificial layer is usually used to release electroformed microstructures. Because of the chemistry applied to the sacrificial layer, only a limited number of metals can be used for electroforming. A novel method to fabricate freestanding electroformed copper structures is presented. A graphite substrate allows the release of the metal part, by abrasive removal of the graphite after electroforming. Results on fabrication of high-aspect-ratio freestanding copper grids are presented; these can be used as x-ray collimator in medical imaging to reduce scattered radiation. This process has potential application to the fabrication of injection molds and microparts on pick-and-place carriers for microelectromechanical systems (MEMS).

Varved sediments of the tropical Cariaco basin provide a new {sup 14}C calibration data set for the period of deglaciation (10,000 to 14,500 years before present: 10-14.5 cal ka BP). Independent evaluations of the Cariasco Basin calendar and {sup 14}C chronologies were based on the agreement of varve ages with the GISP2 ice core layer chronology for similar high-resolution paleoclimate records, in addition to {sup 14}C age agreement with terrestrial {sup 14}C dates, even during large climatic changes. These assessments indicate that the Cariaco Basin {sup 14}C reservoir age remained stable throughout the Younger Dryas and late Alleroed climatic events and that the varve and {sup 14}C chronologies provide an accurate alternative to existing calibrations based on coral U/Th dates. The Cariaco Basin calibration generally agrees with coral-derived calibrations but is more continuous and resolves century-scale details of {sup 14}C change not seen in the coral records. {sup 14}C plateaus can be identified at 9.6, 11.4, and 11.7 {sup 14}C ka BP, in addition to a large, sloping plateau during the Younger Dryas ({approximately}10 to 11 {sup 14}C ka BP). Accounting for features such as these is crucial to determining the relative timing and rates of change during abrupt global …

We report tests of a refuelable zinc/air battery of modular, bipolar-cell design, intended for fleet electric busses and vans. The stack consists of twelve 250-cm{sup 2} cells built of two units: (1) a copper-clad glass-reinforced epoxy board supporting anode and cathode current collectors, and (2) polymer frame providing for air- and electrolyte distribution and zinc fuel storage. The stack was refueled in 4 min. by a hydraulic transfer of zinc particles entrained in solution flow.

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CgWind is a high-fidelity large eddy simulation (LES) tool designed to meet the modeling needs of wind turbine and wind park engineers. This tool combines several advanced computational technologies in order to model accurately the complex and dynamic nature of wind energy applications. The composite grid approach provides high-quality structured grids for the efficient implementation of high-order accurate discretizations of the incompressible Navier-Stokes equations. Composite grids also provide a natural mechanism for modeling bodies in relative motion and complex geometry. Advanced algorithms such as matrix-free multigrid, compact discretizations and approximate factorization will allow CgWind to perform highly resolved calculations efficiently on a wide class of computing resources. Also in development are nonlinear LES subgrid-scale models required to simulate the many interacting scales present in large wind turbine applications. This paper outlines our approach, the current status of CgWind and future development plans.

The principal aim of the National Waste Terminal Storage (NWTS) program is to develop repositories in several different rock formations in various parts of the country. Rocks such as salt, shale, limestone, and granite may qualify as host media for the disposition of radioactive wastes in the proper environments. In general, the only requirement for any rock formation or storage area is that it be able to contain any emplaced wastes for so long as it takes for the radioactive materials to decay to innocuous levels. This requirement, though, is a formidable one because some of the wastes will remain active for periods of hundreds of thousands of years and because the physical and chemical properties of rocks that govern circulating ground water and, hence, the containment may be difficult to determine and define. Rock salt has long been regarded as the most favored geologic medium for the containment of radioactive wastes in the United States. This stems largely from the plastic behavior of salt, which promotes self-healing and otherwise makes it impermeable to circulating ground water. Other important advantages of salt include its wide distribution, ease of mining, and favorable heat dissipation characteristics. In addition to the salt domes …

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Algebraic multigrid (AMG) is an attractive choice for solving large linear systems {Lambda}x = b on unstructured grids. While AMG is applicable as a solver for a variety of problems, its robustness may be enhanced by using it as a preconditioner for Krylov solvers, such as GMRES. The sheer size of modern problems, hundreds of millions or billions of unknowns, dictates the use of massively parallel computers. AMG consists of two phases: the setup phase, in which smaller and smaller linear systems are generated by means of linear transfer operators (interpolation and restriction); and the solve phase, which employs a smoothing operator, such as Gauss-Seidel or Jacobi relaxation. Most of these components can be parallelized in a straightforward fashion; however, the coarse-grid selection, in which the grid for a smaller linear system is created on which the error can be approximated, is highly sequential. It is important to develop parallel coarsening techniques. They briefly present here the coarsening algorithms used in the parallel AMG code ''Boomer AMG'' and summarize some performance results for those algorithms. A detailed discussion of the algorithms and numerical results will be found.

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Despite recent advances in named entity extraction technologies, state-of-the-art extraction tools achieve insufficient accuracy rates for practical use in many operational settings. However, they are not generally prone to the same types of error, suggesting that substantial improvements may be achieved via appropriate combinations of existing tools, provided their behavior can be accurately characterized and quantified. In this paper, we present an inference methodology for the aggregation of named entity extraction technologies that is founded upon a black-box analysis of their respective error processes. This method has been shown to produce statistically significant improvements in extraction relative to standard performance metrics and to mitigate the weak performance of entity extractors operating under suboptimal conditions. Moreover, this approach provides a framework for quantifying uncertainty and has demonstrated the ability to reconstruct the truth when majority voting fails.

Dimensional changes in PBX materials resulting from temperature change are of interest to engineers, designers and modelers. In this paper we present data from recent measurements made on LX17-1, as well as on the material's binder and its energetic constituent. LX17-1 is made from 7.5% KEL-F 800 binder combined with 92.5% wet aminated TATB energetic crystals. Due apparently to the anisotropic expansionary behavior of the TATB, the material exhibits irreversible growth, in addition to the usual reversible expansions and contractions associated with temperature change. In an effort understand reversible and irreversible growth behavior and to verify consistency between our measurements and those made historically, measurements were performed on billet pressed LX17-1, on die pressed TATB, and on KEL-F alone. It is important to realize that, for materials involving TATB, expansionary behavior results from the combined effects of reversible and irreversible (ratchet growth) phenomena.

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WARPrz is a 2.5 dimensional, cylindrically symmetric, electrostatic, particle-in-cell code. It is part of the WARP family of codes which has been developed to study heavy ion fusion driver issues. WARPrz is being used to study the longitudinal dynamics of heavy ion beams including a longitudinal instability that is driven by the impedance of the LINAC accelerating modules. This instability is of concern because it can enhance longitudinal momentum spread; chromatic abhoration in the lens system restricts the amount of momentum spread allowed in the beam in the final focusing system. The impedance of the modules is modeled by a continuum of resistors and capacitors in parallel in WARPrz. We discuss simulations of this instability including the effect of finite temperature and reflection of perturbations off the beam ends. We also discuss intermittency of axial confining fields (``ears`` fields) as a seed for this instability.

Deep Space Program Science Experiment (DSPSE), also known as Clementine, is a collection of science experiments conducted in near-earth with the goal of demonstrating Strategic Defense Initiative Office (SDIO) developed technologies. The 785 lb (fully fueled) spacecraft will be launched into low Earth orbit in February 1994 together with a Star 37 solid kick motor and interstage. After orbit circulation using Clementine`s 110 lb Delta-V thruster, the Star 37 will execute a trans-lunar injection burn that will send the spacecraft toward lunar obit. The 110-lb will then be used in a sequence of burns to insert Clementine into a trimmed, polar orbit around the moon. After a two month moon mapping mission, Clementine will execute burns to leave lunar orbit, sling-shot around Earth, and flyby the moon on a 9.4 million km journey toward the asteroid Geographos. After about three months in transit, Clementine will attempt a flyby with a closest point of approach of 100 km from the asteroid on August 31, 1994. During its approach to Geographos, Clementine will be tracked by the Deep Space Network (DSN) and receive guidance updates. The last update and correction burn will occur about one day out of the flyby. Multiple experiments …

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In this paper, we present the recent results of our research on the high power ultra-fast silicon RF switches. This switch is composed of a group of PIN diodes on a high purity SOI (silicon on oxide) wafer. The wafer is inserted into a cylindrical waveguide under TE01 mode, performing switching by injecting carriers into the bulk silicon. Our current design use a CMOS compatible process and the device was fabricated at SNF (Stanford Nanofabrication Facility). This design is able to achieve sub-100ns switching time, while the switching speed can be improved further with 3-D device structure and faster circuit. Power handling capacity of the switch is at the level of 10MW. The switch was designed for active X-band RF pulse compression systems--especially for NLC, but it is also possible to be modified for other applications and other frequencies such as L-band.

Operating accelerating gradient in normal conducting accelerating structures is often limited by rf breakdown. The limit depends on multiple parameters, including input rf power, rf circuit, cavity shape and material. Experimental and theoretical study of the effects of these parameters on the breakdown limit in full scale structures is difficult and costly. We use 11.4 GHz single-cell traveling wave and standing wave accelerating structures for experiments and modeling of rf breakdown behavior. These test structures are designed so that the electromagnetic fields in one cell mimic the fields in prototype multicell structures for the X-band linear collider. Fields elsewhere in the test structures are significantly lower than that of the single cell. The setup uses matched mode converters that launch the circular TM{sub 01} mode into short test structures. The test structures are connected to the mode launchers with vacuum rf flanges. This setup allows economic testing of different cell geometries, cell materials and preparation techniques with short turn-around time. Simple 2D geometry of the test structures simplifies modeling of the breakdown currents and their thermal effects.

GLAST (Gamma-ray Large Area Space Telescope) is a gamma-ray astronomy mission that will be launched in mid 2007. The main instrument is the LAT (Large Area Telescope), a pair conversion telescope with sensitivity in the range 20 MeV-300 GeV. Data Challenge One (DC1) was the simulation of one week of observation of the entire gamma-ray sky by the LAT detector. the simulated data was similar to the real data, which allowed for the development of scientific software. In this paper they present the GRB simulations and the detection algorithms developed by the GLAST GRB and Solar Flare Science Team.

Electron-positron colliders have been operating in a top-up-and-coast fashion with a cycle time depending on the beam life time, typically one or more hours. Each top-up involves ramping detector systems in addition to the actual filling time. The loss in accumulated luminosity may be 20-50%. During the last year, both B-Factories have commissioned a continuous-injection mode of operation in which beam is injected without ramping the detector, thus raising luminosity integration by always operating at peak luminosity. Constant beam currents also reduce thermal drift and trips caused by change in beam loading. To achieve this level of operation, special efforts were made to reduce the injection losses and also to implement gating procedures in the detectors, minimizing dead time. Beam collimation can reduce injection noise but also cause an increase in background rates. A challenge can be determining beam lifetime, important to maintain tuning of the beams.

Beam-beam deflection scans provide important beam diagnostics at the interaction point of a linear collider. Beam properties such as spot sizes, alignment, and waists are measured by sweeping one beam across the other. Proposed linear colliders use trains of bunches; if beam-beam scans can be done within the time of a bunch-train crossing rather than integrating over the bunch train, the acquisition rate of diagnostic information can be increased and the sensitivity of the scan to pulse-to-pulse jitter and slow drifts reduced. The existence of intra-train deflection feedback provides most of the hardware needed to implement intra-train beam-beam scans for diagnostic purposes. A conceptual design is presented for such beam-beam scans at the Next Linear Collider (NLC).

Instabilities in the gun region of a high-power klystron can occur when there is positive feedback between a mode and an induced current on the quasi-steady state beam emitted by the gun cathode[1]. This instability is dependent on the gun voltage, and is predicted on the basis of a negative total Q. The established method for computing the beam-loaded Q of a cavity involves using a time-dependent electromagnetic particle-in-cell (PIC) code to track beam particles through the quasi-static gun fields perturbed by the electromagnetic fields of a cavity eigenmode[2]. The energy imparted to the beam by the mode is obtained by integrating the Lorentz force along the particle tracks, and this quantity is simply related to the beam-loaded Q. We have developed an alternative approach that yields comparable accuracy but is computationally much simpler. The new method is based on a time-independent electrostatic PIC calculation, resulting in much faster solutions without loss of accuracy. We will present the theory and implementation of the new method, as well as benchmarks and results from analysis of the XP-4 klystron that show a potential instability near 3 GHz.