We present our approach to enabling approximate ad hoc queries on terabyte-scale mesh data generated from large scientific simulations through the extension and integration of database, statistical, and data mining techniques. There are several significant barriers to overcome in achieving this objective. First, large-scale simulation data is already at the multi-terabyte scale and growing quickly, thus rendering traditional forms of interactive data exploration and query processing untenable. Second, a priori knowledge of user queries is not available, making it impossible to tune special-purpose solutions. Third, the data has spatial and temporal aspects, as well as arbitrarily high dimensionality, which exacerbates the task of finding compact, accurate, and easy-to-compute data models. Our approach is to preprocess the mesh data to generate highly compressed, lossy models that are used in lieu of the original data to answer users' queries. This approach leads to interesting challenges. The model (equivalently, the content-oriented metadata) being generated must be smaller than the original data by at least an order of magnitude. Second, the metadata representation must contain enough information to support a broad class of queries. Finally, the accuracy and speed of the queries must be within the tolerances required by users. In this paper we …

Over the course of the year 2000, five workshops were conducted by the Center for Global Security Research at the Lawrence Livermore National Laboratory on threats to international security in the 2015 to 2020 timeframe due to the global availability of advanced technology. These workshops focused on threats that are enabled by nuclear, missile, and space technology; military technology; information technology; bio technology; and geo systems technology. The participants included US national leaders and experts from the Department of Energy National Laboratories; the Department of Defense: Army, Navy, Air Force, Office of the Secretary of Defense, Defense Threat Reduction Agency, and Defense Advanced Research Projects Agency; the Department of State, NASA, Congressional technical staff, the intelligence community, universities and university study centers, think tanks, consultants on security issues, and private industry. For each workshop the process of analysis involved identification and prioritization of the participants' perceived most severe threat scenarios (worst nightmares), discussion of the technologies which enabled those threats, and ranking of the technologies' threat potentials. The threats ranged from local/regional to global, from intentional to unintended to natural, from merely economic to massively destructive, and from individual and group to state actions. We were not concerned in this …

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The NIF Integrated Computer Control System (ICCS) application software uses a set of service frameworks that assures uniform behavior spanning the front-end processors (FEPs) and supervisor programs. This uniformity is visible both in the way each program employs shared services and in the flexibility it affords for attaching graphical user interfaces (GUIs). Uniformity of structure across applications is desired for the benefit of programmers who will be maintaining the many programs that constitute the ICCS. In this paper, the framework components that have the greatest impact on the application structure are discussed.

The increased use of object-oriented toolkits in large-scale scientific simulation presents new opportunities and challenges for the use of automatic (or algorithmic) differentiation (AD) techniques, especially in the context of optimization. Because object-oriented toolkits use well-defined interfaces and data structures, there is potential for simplifying the AD process. Furthermore, derivative computation can be improved by exploiting high-level information about numerical and computational abstractions. However, challenges to the successful use of AD with these toolkits also exist. Among the greatest challenges is balancing the desire to limit the scope of the AD process with the desire to minimize the work required of a user. They discuss their experiences in integrating AD with the PETSc, PVODE, and TAO toolkits and the plans for future research and development in this area.

A study was performed to elucidate the chemical-kinetic mechanism of combustion of toluene. A detailed chemical-kinetic mechanism for toluene was improved by adding a more accurate description of the phenyl + O{sub 2} reaction channels, toluene decomposition reactions and the benzyl + 0 reaction. Results of the chemical kinetic mechanism are compared with experimental data obtained from premixed and nonpremixed systems. Under premixed conditions, predicted ignition delay times are compared with new experimental data obtained in shock tube. Also, calculated species concentration histories are compared to experimental flow reactor data from the literature. Under nonpremixed conditions, critical conditions of extinction and autoignition were measured in strained laminar flows in the counterflow configuration. Numerical calculations are performed using the chemical-kinetic mechanism at conditions corresponding to those in the experiments. Critical conditions of extinction and autoignition are predicted and compared with the experimental data. Comparisons between the model predictions and experimental results of ignition delay times in shock tube, and extinction and autoignition in nonpremixed systems show that the chemical-kinetic mechanism predicts that toluene/air is overall less reactive than observed in the experiments. For both premixed and nonpremixed systems, sensitivity analysis was used to identify the reaction rate constants that control the …

Dimming controls for electric lighting have been one of the mainstays of the effort to use daylighting to reduce annual lighting energy consumption. The coincidence of daylighting with electric utility peak demand makes daylighting controls an effective strategy for reducing commercial building peak electric loads. During times of energy shortage, there is a greatly increased need to reduce electricity use during peak periods, both to ease the burden on electricity providers and to control the operating costs of buildings. The paper presents a typical commercial building electric demand profile during summer, and shows how daylighting-linked lighting controls and load shedding techniques can reduce lighting at precisely those times when electricity is most expensive. We look at the importance of dimming for increasing the reliability of the electricity grid in California and other states, as well as examine the potential cost-effectiveness of widespread use of daylighting to save energy and reduce monthly electricity bills.

In this paper, we discuss the specific issues related to the design of the Fast Kicker Systems for high intensity proton accelerators. To address these issues in the preliminary design stage can be critical since the fast kicker systems affect the machine lattice structure and overall design parameters. Main topics include system architecture, design strategy, beam current coupling, grounding, end user cost vs. system cost, reliability, redundancy and flexibility. Operating experience with the Alternating Gradient Synchrotron injection and extraction kicker systems at Brookhaven National Laboratory and their future upgrade is presented. Additionally, new conceptual designs of the extraction kicker for the Spallation Neutron Source at Oak Ridge and the Advanced Hydrotest Facility at Los Alamos are discussed.

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Detailed chemical kinetic reaction mechanisms are developed for combustion of all nine isomers of heptane (C{sub 7}H{sub 16}), and these mechanisms are tested by simulating autoignition of each isomer under rapid compression machine conditions. The reaction mechanisms focus on the manner in which the molecular structure of each isomer determines the rates and product distributions of possible classes of reactions. The reaction pathways emphasize the importance of alkylperoxy radical isomerizations and addition reactions of molecular oxygen to alkyl and hydroperoxyalkyl radicals. A new reaction group has been added to past models, in which hydroperoxyalkyl radicals that originated with abstraction of an H atom from a tertiary site in the parent heptane molecule are assigned new reaction sequences involving additional internal H atom abstractions not previously allowed. This process accelerates autoignition in fuels with tertiary C-H bonds in the parent fuel. In addition, the rates of hydroperoxyalkylperoxy radical isomerization reactions have all been reduced so that they are now equal to rates of analogous alkylperoxy radical isomerizations, significantly improving agreement between computed and experimental ignition delay times in the rapid compression machine. Computed ignition delay times agree well with experimental results in the few cases where experiments have been carried out …

We are conducting research into the direct electrochemical conversion of reactive carbons into electricity--with experimental evidence of total efficiencies exceeding 80% of the heat of combustion of carbon. Together with technologies for extraction of reactive carbons from broad based fossil fuels, direct carbon conversion addresses the objectives of DOE's ''21st Century Fuel Cell'' with exceptionally high efficiency (>70% based on standard heat of reaction, {Delta}H{sub std}), as well as broader objectives of managing CO{sub 2} emissions. We are exploring the reactivity of a wide range of carbons derived from diverse sources, including pyrolyzed hydrocarbons, petroleum cokes, purified coals and biochars, and relating their electrochemical reactivity to nano/microstructural characteristics.

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In this article, the authors compare the effects of O2, Ar, and H2 gases on the field-emission (FE) properties of single-walled carbon nanotubes (SWNTs) and multiwalled carbon nanotubes (MWNTs).

We report on the experimental results of the dielectric based two beam accelerator (step-up transformer). By using a single high charge beam, we have generated and extracted a high power RF pulse from a 7.8 GHz primary dielectric structure and then subsequently transferred to a second accelerating structure with higher dielectric constant and smaller transverse dimensions. We have measured the energy change of a second (witness) beam passing through the acceleration stage. The measured gradient is > 4 times the deceleration gradient. The detailed experiment of set-up and results of the measurements are discussed. Future plans for the development of a 100 MeV demonstration accelerator based on this technique is presented.

Researchers at Brookhaven National Laboratory and the National Renewable Energy Laboratory have tested polymer-based coating systems to reduce the capital equipment and maintenance costs of heat exchangers in corrosive and fouling geothermal environments. These coating systems act as barriers to corrosion to protect low-cost carbon steel tubing; they are formulated to resist wear from hydroblasting and to have high thermal conductivity. Recently, new filler materials have been developed for coating systems that use polyphenylenesulphide as a matrix. These materials include boehmite crystals (orthorhombic aluminum hydroxide, which is grown in situ as a product of reaction with the geothermal fluid), which enhance wear and corrosion resistance, and carbon fibers, which improve mechanical, thermal, and corrosion-resistance properties of the composite.

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We have performed high resolution transmission electron microscope (HRTEM) image simulations to qualitatively assess the visibility of various structural defects in ultra-thin gate oxides of MOSFET devices, and to quantitatively examine the accuracy of HRTEM in performing gate oxide metrology. Structural models contained crystalline defects embedded in an amorphous 16 {angstrom}-thick gate oxide. Simulated images were calculated for structures viewed in cross-section. Defect visibility was assessed as a function of specimen thickness and defect morphology, composition, size and orientation. Defect morphologies included asperities lying on the substrate surface, as well as ''bridging'' defects connecting the substrate to the gate electrode. Measurements of gate oxide thickness extracted from simulated images were compared to actual dimensions in the model structure to assess TEM accuracy for metrology. The effects of specimen tilt, specimen thickness, objective lens defocus and coefficient of spherical aberration (C{sub s}) on measurement accuracy were explored for nominal 10{angstrom} gate oxide thickness. Results from this work suggest that accurate metrology of ultra-thin gate oxides (i.e. limited to several per cent error) is feasible on a consistent basis only by using a C{sub s}-corrected microscope. However, fundamental limitations remain for characterizing defects in gate oxides using HRTEM, even with the new …

One disadvantage of conventional iris-loaded accelerating structures is the high ratio of the peak surface electric field to the peak axial electric field useful for accelerating a beam. Typically this ratio E{sub s}/E{sub a} {ge} 2. The high surface electric field relative to the accelerating gradient may prove to be a limitation for realizing technologies for very high gradient accelerators. In this paper, we present a scheme that uses a hybrid dielectric and iris loaded periodic structure to reduce E{sub s}/E{sub a} to near unity, while the shunt impedance per unit length r and the quality factor Q compare favorably with conventional metallic structures. The analysis based on MAFIA simulations of such structures shows that we can lower the peak surface electric field close to the accelerating gradient while maintaining high acceleration efficiency as measured by r/Q. Numerical examples of X-band hybrid accelerating structures are given.

A new code, named Hybrid Molecular Dynamics--Kinetic Monte Carlo (Hybrid MD/KMC), has been developed and employed to analyze possible growth pathways that lead to high molecular mass compounds. The Hybrid MD-KMC code combines the strengths of two common simulation methods: Kinetic Monte Carlo, and Molecular Dynamics. This code puts the two simulation procedures on an equal footing and involves alternating between MD and KMC steps during the simulation. The strength of this approach is that it provides information on the physical as well as chemical structure of soot precursors providing at the long term potential for information on particle characteristics such as density, porosity, and other physical properties. The Kinetic Monte Carlo and Molecular Dynamics simulation are used in conjunction with high-level quantum chemical calculations.

There are a number of novel instrumentation issues relating to the generation cooling and acceleration of high power muon beams. Specific issues are monitoring the cooling water in the magnet nearest the target to minimize corrosion, monitoring the behavior of the target after the impact of the beam, and following the beam through the cooling accelerator chain. The muon cooling system also produces a number of unique issues such as making beam profile measurements in the presence of large backgrounds, measuring these backgrounds, losses, and the angular momentum of the beam. We describe the techniques we intend to use, and some of the constraints involved in their implementation.

The interaction of strong shock waves, such as those generated by the explosion of supernovae with interstellar clouds, is a problem of fundamental importance in understanding the evolution and the dynamics of the interstellar medium (ISM) as it is disrupted by shock waves. The physics of this essential interaction is critical to understanding the evolution of the ISM, the mixing of interstellar clouds with the ISM and the viability of this mechanism for triggered star formation. Here we present the results of a series of new OMEGA laser experiments investigating the evolution of a high density sphere embedded in a low density medium after the interaction of a strong shock wave, thereby emulating the supernova shock-cloud interaction. The interaction is viewed from two orthogonal directions enabling visualization of the both the initial distortion of the sphere into a vortex ring as well as the onset of an azimuthal instability that ultimately results in the three-dimensional breakup of the ring. These studies augment previous studies [1,2] on the NOVA laser by enabling the full three-dimensional topology of the interaction to be understood. We show that the experimental results for the vortex ring are in remarkable agreement with the incompressible theory of …

An analytical system is presented that is used to take measurements of objects perceived in stereo image pairs obtained from a scanning electron microscope (SEM). Our system operates by presenting a single stereo view that contains stereo image data obtained from the SEM, along with geometric representations of two types of virtual measurement instruments, a ''protractor'' and a ''caliper''. The measurements obtained from this system are an integral part of a medical study evaluating surfactant, a liquid coating the inner surface of the lung which makes possible the process of breathing. Measurements of the curvature and contact angle of submicron diameter droplets of a fluorocarbon deposited on the surface of airways are performed in order to determine surface tension of the air/liquid interface. This approach has been extended to a microscopic level from the techniques of traditional surface science by measuring submicrometer rather than millimeter diameter droplets, as well as the lengths and curvature of cilia responsible for movement of the surfactant, the airway's protective liquid blanket. An earlier implementation of this approach for taking angle measurements from objects perceived in stereo image pairs using a virtual protractor is extended in this paper to include distance measurements and to use …

Parameterization of cumulus convection in general circulation model (GCM) has been recognized as one of the most important and complex issues in the model physical parameterizations. In earlier studies, most cumulus parameterizations were developed and evaluated using data observed over tropical oceans, such as the GATE (the Global Atmospheric Research Program's Atlantic Tropical Experiment) data. This is partly due to inadequate field measurements in the midlatitudes. In this study, we compare and evaluate a total of eight types of the state-of-the-art cumulus parameterizations used in fifteen Single-Column Models (SCM) under the summertime midlatitude continental conditions using the Atmospheric Radiation Measurement (ARM) Southern Great Plains (SGP) summer 1997 Intensive Operational Period (IOP) data, which covers several continental convection events. The purpose is to systematically compare and evaluate the performance of these cumulus parameterizations under summertime midlatitude continental conditions. Through the study we hope to identify strengths and weaknesses of these cumulus parameterizations that will lead to further improvements. Here, we briefly present our most interesting results. A full description of this study can be seen in Xie et al. (2001). The authors conclude that: (1) The SCM simulation errors are closely related to problems with model cumulus parameterizations. The schemes with …