This paper focuses on our recent work at Sandia National Laboratories toward engineering a physics-based swarm of mobile vehicles for distributed sensing applications. Our goal is to coordinate a sensor array that optimizes sensor coverage and multivariate signal analysis by implementing artificial intelligence and evolutionary computational techniques. These intelligent control systems integrate both globally operating decision-making systems and locally cooperative information-sharing modes using genetically-trained neural networks. Once trained, neural networks have the ability to enhance real-time operational responses to dynamical environments, such as obstacle avoidance, responding to prevailing wind patterns, and overcoming other natural obscurants or interferences (jammers). The swarm realizes a collective set of sensor neurons with simple properties incorporating interactions based on basic community rules (potential fields) and complex interconnecting functions based on various neural network architectures, Therefore, the swarm is capable of redundant heterogeneous measurements which furnishes an additional degree of robustness and fault tolerance not afforded by conventional systems, while accomplishing such cognitive tasks as generalization, error correction, pattern recognition, and sensor fission. The robotic platforms could be equipped with specialized sensor devices including transmit/receive dipole antennas, chemical or biological sniffers in combination with recognition analysis tools, communication modulators, and laser diodes. Our group has been …

We review the progress made by amorphous silicon solar cells, including the emerging technology of solar cells of microcrystalline silicon. The long-term trend in the efficiency of stabilized laboratory cells based on a-Si:H has been a rise of {approx}0.6 % per year. The recent trend in the a-Si,Ge:H cell efficiency alone, measured in the spectral window assigned to the bottom device in a triple-junction cell, has been an increase of {approx}0.16% per year. These improvements have brought within reach the target of 15% efficiency identified by EPRI and DOE for widespread application. Our review leads to an identification of areas of promising research, with emphasis on the fundamental science required to reach the 15% target, and then to move to the next-level efficiency goal.

The Los Alamos National Laboratory Colt facility has been used to create target plasma for Magnetized Target Fusion (MTF). The primary results regarding magnetic field, plasma density, plasma temperature, and hot plasma lifetime are summarized and the suitability of these plasma targets for MTF is assessed.

In an effort to more easily assess various combinations of 3-D neutronic/thermal-hydraulic codes, the USNRC has sponsored the development of a generalized interface module for the coupling of any thermal-hydraulics code to any spatial kinetics code. In this design, the thermal-hydraulics, general interface, and spatial kinetics codes function independently and utilize the Parallel Virtual Machine (PVM) software to manage inter-process communication. Using this interface, the USNRC version of the 3D neutron kinetics code, PARCS, has been coupled to the USNRC system analysis codes RELAP5 and TRAC-M. RELAP5/PARCS assessment results are presented for an OECD/NEA main steam line break benchmark problem. The assessment of TRAC-M/PARCS has only recently been initiated; nonetheless, the capabilities of the coupled code are presented for the OECD/NEA main steam line break benchmark problem.

We report on the application of the one-level FETI method to the solution of a class of structural problems associated with the Department of Energy's Accelerated Strategic Computing Initiative (ASCI). We focus on numerical and parallel scalability issues,and discuss the treatment by FETI of severe structural heterogeneities. We also report on preliminary performance results obtained on the ASCI Option Red supercomputer configured with as many as one thousand processors, for problems with as many as 5 million degrees of freedom.

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The Accelerator Production of Tritium (APT) Target/Blanket (T/B) system is comprised of an assembly of tritium producing modules supported by control, heat removal, shielding and retargeting systems. The T/B assembly produces tritium using a high-energy proton beam, a tungsten/lead spallation neutron source and {sup 3}He gas as the tritium producing feedstock. For the nominal production mode, protons are accelerated to an energy of 1030 MeV at a current of 100 mA and are directed onto the T/B assembly. The protons are expanded using a raster/expansion system to illuminate a 0.19m by 1.9m beam spot on the front face of a centrally located tungsten neutron source. A surrounding lead blanket produces additional neutrons from scattered high-energy particles. The tungsten neutron source consists of nested, Inconel-718 clad tungsten cylinders assembled in horizontal Inconel-718 tubes. Each tube contains up to 6 cylinders with annular flow channel gaps of 0.102 cm. These horizontal tubes are manifolded into larger diameter vertical inlet and outlet pipes, which provide coolant. The horizontal and vertical tubes make up a structure similar to that of rungs on a ladder. The entire tungsten neutron source consists of 11 such ladders separated into two modules, one containing five ladders and the …

This paper examines three thin-film PV technologies: amorphous silicon, cadmium telluride, and copper indium selenide. The purpose is to: (1) assess their status and potential; (2) provide an improved set of criteria for comparing these existing thin films against any new PV technological alternatives, and examining the longer-term (c. 2050) potential of thin films to meet cost goals that would be competitive with conventional sources of energy without any added value from the substantial environmental advantages of PV. Among the conclusions are: (1) today's thin films have substantial economic potential, (2) any new approach to PV should be examined against the substantial achievements and potential of today's thin films, (3) the science and technology base of today's thin films needs substantial strengthening, (4) some need for alternative technologies exists, especially as the future PV marketplace expands beyond about 30 GW of annual production.

A brief review is presented of fundamental research topics of primary importance to the development of improved solar cells based on chalcopyrite-structure materials. The opinions presented are a consensus opinion of the authors of the paper, with input from members of the chalcopyrite solar cells research community in the United States. Major topical areas identified included, in order of importance, are (1) development of an integrated predictive understanding of CIGS(S) materials and devices, (2) development of novel deposition techniques and characterization of the mechanisms of growth in existing and novel processes, (3) novel materials, especially with wide-energy gaps (is greater than or equal to 1.7 eV) other than Cu-based chalcopyrites, (4) development of real-time material characterizations for process control, and (5) alternative front- and rear-contact materials. Although the five topics identified are quite broad, they do not include all topics of interest. Also discussed briefly are some other potential research areas not in the highest priority topics, in particular, areas identified as primarily ''engineering'' rather than ''science.''

Photovoltaic (PV) technology for conversion of sunlight to electricity is the most cost-effective method for meeting the electric power needs of many consumers around the world today. This document is the preface and executive summary from the workshop to be held in May 1999 in Seattle, Washington.

As the Jefferson Lab Free Electron Laser steadily approaches its goal of producing 1 kW of IR radiation at 5 mA of beam current at 42 MeV, plans are being considered for possible upgrade scenarios, which will extend the IR power output and allow generation of UV radiation. The upgrade scenario presently considered will bring the beam current to 10 mA and increase the energy to values close to 200 MeV. These parameters will most likely be realized in a machine configuration with a single recirculation loop for energy recovery and a linac consisting of three IRFEL-type cryomodules. Measurements of frequencies and external Q's of the revealed anomalous high-Q resonances which could lead to transverse BBU instabilities at currents close to the operating current of the machine. In this paper the authors use the simulation code TDBBU to study the BBU behavior of the FEL upgrade and estimate its threshold current under nominal settings. Furthermore, they study its dependencies on small variations of machine parameters, such as the path length of the recirculator and the frequency of selected HOMs, around their nominal points.

A series of beam experiments is being planned in the Jefferson Lab FEL driver accelerator in order to study multi-pass beam breakup instabilities in the machine and to test the predictions of the numerical code TDBBU. The tests are extensions of previously performed or proposed experiments, and will be considerably more sensitive with the present configuration. The experiments will include: (a) observing the onset of instabilities by lowering the threshold current through manipulation of the beam energy, phase advance, and beam transfer matrices; (b) measurements of beam transfer functions in the recirculating mode; and (c) measurements of the single pass beam transfer functions to obtain direct measurements of the transverse shunt impedance of cavity modes with strong coupling to the beam. Simulations of the different experiments and studies of the sensitivities to the accelerator and beam parameters are presented.

Buildings often do not perform as well in practice as expected during pre-design planning, nor as intended at the design stage. While this statement is generally considered to be true, it is difficult to quantify the impacts and long-term economic implications of a building in which performance does not meet expectations. This leads to a building process that is devoid of quantitative feedback that could be used to detect and correct problems both in an individual building and in the building process itself. One key element in this situation is the lack of a standardized method for documenting and communicating information about the intended performance of a building. This paper describes the Building Life-cycle Information System (BLISS); designed to manage a wide range of building related information across the life cycle of a building project. BLISS is based on the Industry Foundation Classes (IFC) developed by the International Alliance for Interoperability. A BLISS extension to th e IFC that adds classes for building performance metrics is described. Metracker, a prototype tool for tracking performance metrics across the building life cycle, is presented.

Experimental Hall B at Jefferson Laboratory houses the CEBAF Large Acceptance Spectrometer, the magnetic field of which is produced by a superconducting toroid. The six coils of this toroid divide the detector azimuthally into six sectors, each of which contains three large multi-layer drift chambers for tracking charged particles produced from a fixed target on a toroidal axis. Within the 18 drift chambers are a total of 35,148 individually instrumented hexagonal drift cells. The novel geometry of these chambers provides for good tracking resolution and efficiency, along with large acceptance. The design and construction challenges posed by these large-scale detectors are described, and detailed results are presented from in-beam measurements.

A vexing feature in granular materials compaction is density extrema interior to a compacted shape. Such inhomogeneities can lead to weaknesses and loss of dimensional control in ceramic parts, unpredictable dissolution of pharmaceuticals, and undesirable stress concentration in load-bearing soil. As an example, the centerline density in a cylindrical compact often does not decrease monotonically from the pressure source but exhibits local maxima and minima. Two lines of thought in the literature predict, respectively, diffusive and wavelike propagation of stress. Here, a general memory function approach has been formulated that unifies these previous treatments as special cases; by analyzing a convenient intermediate case, the telegrapher's equation, one sees that local density maxima arise via semidiffusive stress waves reflecting from the die walls and adding constructively at the centerline.

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X-ray computed tomography (CT) imaging techniques in nondestructive evaluation (NDE) have seen increasing use in an array of industrial, environmental, military, and medical applications (Goebbels, et al., 1999). A brief overview and three diverse application studies of x-ray CT at the Lawrence Livermore National Laboratory (LLNL) will be discussed. (1) Bridge pins are fracture critical elements for some multi-span steel bridges. Recently, pins were removed from their hanger pin assemblies. These pins were selected for further examination by laboratory NDE techniques. High-energy x-ray radiography and CT were used to characterize these pins. (2) Cast light metals, aluminum and magnesium, are being used in an ever increasing number of applications to reduce automobile weight for improved gas mileage and lower emissions. After mechanical testing, the damage in notched Al-tensile test specimens was first determined using CT and subsequently by metallography analysis intended to benchmark the CT technique. (3) A computational approach to normal joint kinematics and prosthetic joint analysis offers an opportunity to evaluate and improve prosthetic joint replacements before they are manufactured or surgically implanted. Computed tomography data are combined with computational analysis to reveal regions where the joint design can be improved for better performance and longevity, prior to …

As part of a project for the Defense Advanced Research Projects Agency, Sandia National Laboratories is developing and testing the feasibility of using of a cooperative team of robotic sentry vehicles to guard a perimeter and to perform surround and diversion tasks. This paper describes on-going activities in the development of these robotic sentry vehicles. To date, we have developed a robotic perimeter detection system which consists of eight ''Roving All Terrain Lunar Explorer Rover'' (RATLER{trademark}) vehicles, a laptop-based base-station, and several Miniature Intrusion Detection Sensors (MIDS). A radio frequency receiver on each of the RATLER vehicles alerts the sentry vehicles of alarms from the hidden MIDS. When an alarm is received, each vehicle decides whether it should investigate the alarm based on the proximity of itself and the other vehicles to the alarm. As one vehicle attends an alarm, the other vehicles adjust their position around the perimeter to better prepare for another alarm. We have also demonstrated the ability to drive multiple vehicles in formation via tele-operation or by waypoint GPS navigation. This is currently being extended to include mission planning capabilities. At the base-station, the operator can draw on an aerial map the goal regions to be …

The existence of six crystallographic allotropes from room temperature up to the solid-liquid transition just above 913 K at atmospheric pressure makes solid Plutonium unique among the elements in the periodic table. Among these phases (labeled {alpha}, {beta}, {gamma}, {delta}{delta}{prime}), and {var_epsilon}, the {delta} phase, stable between 593 K and 736 K, has commanded considerable interest in the metallurgical and solid state communities. In contrast to the low-temperature monoclinic {alpha} phase, which is brittle, the face-centered cubic (fcc) {delta} phase is ductile, a property that makes it convenient for engineering applications. This phase can also be stabilized through alloying with a number of other elements such as Ga, Al, Sc, and Am.

An important need while using robots or remotely operated equipment is the ability for the operator or an observer to easily and accurately perceive the operating environment. A classic problem in providing a complete representation of a work area is sensory overload or excessive complexity in the human–machine interface. In addition, remote operations often benefit from depth perception capability while viewing or manipulating objects. Thus, there is an on going effort within the robotic field to develop simplified telepresence interfaces. The Department of Energy’s Idaho National Engineering and Environmental Laboratory (INEEL) has been researching methods to generalize a human-machine interface for telepresence applications. Initial telepresence research conducted at the INEEL developed and implemented a concept called the VirtualwindoW. This system minimized the complexity of remote stereo viewing controls and provided the operator the “feel” of viewing the environment, including depth perception, in a natural setting. The VirtualwindoW has shown that the human-machine interface can be simplified while increasing operator performance. This paper deals with the continuing research and development of the VirtualwindoW to provide a generalized, reconfigurable system that easily utilizes commercially available components. The original system has now been expanded to include support for zoom lenses, camera blocks, wireless …

An important need while using robots or remotely operated equipment is the ability for the operator or an observer to easily and accurately perceive the operating environment. A classic problem in providing a complete representation of a work area is sensory overload or excessive complexity in the human�machine interface. In addition, remote operations often benefit from depth perception capability while viewing or manipulating objects. Thus, there is an on going effort within the robotic field to develop simplified telepresence interfaces. The Department of Energy�s Idaho National Engineering and Environmental Laboratory (INEEL) has been researching methods to generalize a human-machine interface for telepresence applications. Initial telepresence research conducted at the INEEL developed and implemented a concept called the VirtualwindoW. This system minimized the complexity of remote stereo viewing controls and provided the operator the �feel� of viewing the environment, including depth perception, in a natural setting. The VirtualwindoW has shown that the human-machine interface can be simplified while increasing operator performance. This paper deals with the continuing research and development of the VirtualwindoW to provide a generalized, reconfigurable system that easily utilizes commercially available components. The original system has now been expanded to include support for zoom lenses, camera blocks, wireless …

Easy-to-use interfaces are a class of interfaces that fall between public access interfaces and graphical user interfaces in usability and cognitive difficulty. We describe characteristics of easy-to-use interfaces by the properties of four dimensions: selection, navigation, direct manipulation, and contextual metaphors. Another constraint we introduced was to include as little text as possible, and what text we have will be in at least four languages. Formative evaluations were conducted to identify and isolate these characteristics. Our application is a visual interface for a home automation system intended for a diverse set of users. The design will be expanded to accommodate the visually disabled in the near future.

In this presentation the electron field emission and electrical conductivity of undoped and nitrogen doped DLC films have been investigated. Undoped and nitrogen doped DLC films were grown by PE CVD from CH{sub 4}:H{sub 2} and CH{sub 4}:H{sub 2}:N{sub 2} gas mixtures, correspondingly. During nitrogen doped DLC film deposition, the nitrogen content in the gas mixture was varied within the range 0 to 45%. In-situ gas-phase doping allowed them to deposit DLC films with different content nitrogen. DLC films were deposited under three different levels of gas pressure in the chamber: 0.2, 0.6 and 0.8 Torr. The measurements of emission current from samples were performed in the vacuum system which could be pumped to a stable pressure of 10{sup {minus}6} Torr. The emission current was measured in the diode structure. The emitter-anode spacing L was constant and equal to 20 {micro}m. The current-voltage characteristics of the Si field electron emission arrays covered with undoped and nitrogen doped DLC films show that at the beginning the threshold voltage (V{sub th}) increases remarkably with nitrogen content, then V{sub th} is observed to decrease and finally V{sub th} increases. Corresponding Fowler-Nordheim (F-N) plots follow F-N tunneling over a wide range. The F-N plots …

A simple and elegant model, based on Reggeized t-channel exchanges, is successful in reproducing the main features of all existing data of the reactions ep-->e'K{sup +}Sigma{sup 0}. In particular, the original way in which gauge invariance is taken into account is found to be essential to describe the ration between the Coulomb and the transverse cross sections at large Q{sup 2} that has been measured recently at Jefferson Laboratory.