Publications

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Sandia National Laboratories and General Motors Global Energy Systems team conducted a joint biofuels systems analysis project from March to November 2008. The purpose of this study was to assess the feasibility, implications, limitations, and enablers of large-scale production of biofuels. 90 billion gallons of ethanol (the energy equivalent of approximately 60 billion gallons of gasoline) per year by 2030 was chosen as the book-end target to understand an aggressive deployment. Since previous studies have addressed the potential of biomass but not the supply chain rollout needed to achieve large production targets, the focus of this study was on a comprehensive systems understanding the evolution of the full supply chain and key interdependencies over time. The supply chain components examined in this study included agricultural land use changes, production of biomass feedstocks, storage and transportation of these feedstocks, construction of conversion plants, conversion of feedstocks to ethanol at these plants, transportation of ethanol and blending with gasoline, and distribution to retail outlets. To support this analysis, we developed a 'Seed to Station' system dynamics model (Biofuels Deployment Model - BDM) to explore the feasibility of meeting specified ethanol production targets. The focus of this report is water and its linkage to broad scale biofuel deployment.

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The Intergovernmental Panel on Climate Change (IPCC) Fourth Assessment Report (AR4) made extensive use of coordinated simulations by 18 international modeling groups using a variety of coupled general circulation models (GCMs) with different numerics, algorithms, resolutions, physics models, and parameterizations. These simulations span the 20th century and provide forecasts for various carbon emissions scenarios in the 21st century. All the output from this panoply of models is made available to researchers on an archive maintained by the Program for Climate Model Diagnosis and Intercomparison (PCMDI) at LLNL. I have downloaded this data and completed the first steps toward a statistical analysis of these ensembles for the US Southwest. This constitutes the final report for a late start LDRD project. Complete analysis will be the subject of a forthcoming report.

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Improvised Explosive Device (IED) defeat (IEDD) operations can involve intricate operations that exceed the current capabilities of the grippers on board current bombsquad robots. The Shadow Dexterous Hand from the Shadow Robot Company or 'ShadowHand' for short (www.shadowrobot.com) is the first commercially available robot hand that realistically replicates the motion, degrees-of-freedom and dimensions of a human hand (Figure 1). In this study we evaluate the potential for the ShadowHand to perform potential IED defeat tasks on a mobile platform.

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The purpose of this LDRD was to generate data that could be used to populate and thereby reduce the uncertainty in global carbon cycle models. These efforts were focused on developing a system for determining the dissolution rate of biogenic calcite under oceanic pressure and temperature conditions and on carrying out a digital transcriptomic analysis of gene expression in response to changes in pCO2, and the consequent acidification of the growth medium.

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We describe the current state-of-the-art in Trusted Computing Technologies - focusing mainly on Intel's Trusted Execution Technology (TXT). This document is based on existing documentation and tests of two existing TXT-based systems: Intel's Trusted Boot and Invisible Things Lab's Qubes OS. We describe what features are lacking in current implementations, describe what a mature system could provide, and present a list of developments to watch. Critical systems perform operation-critical computations on high importance data. In such systems, the inputs, computation steps, and outputs may be highly sensitive. Sensitive components must be protected from both unauthorized release, and unauthorized alteration: Unauthorized users should not access the sensitive input and sensitive output data, nor be able to alter them; the computation contains intermediate data with the same requirements, and executes algorithms that the unauthorized should not be able to know or alter. Due to various system requirements, such critical systems are frequently built from commercial hardware, employ commercial software, and require network access. These hardware, software, and network system components increase the risk that sensitive input data, computation, and output data may be compromised.

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Through the vehicle of a case study, this paper describes in detail how the guidance found in the suite of IPC (Association Connecting Electronics Industries) publications can be applied to develop a high level of design assurance that flexible printed boards intended for continuous flexing applications will satisfy specified lifetime requirements.

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The excitement surrounding the marriage of biosensors and nanotechnology is palpable even from a cursory examination of the scientific literature. Indeed, the word “nano” might be in danger of being overused and reduced to a cliché, although probably essential for publishing papers or securing research funding. The biosensor literature is littered with clever or catchy acronyms, birds being apparently favored (“CANARY”, “SPARROW”), quite apart from “electronic tongue,” “electronic nose,” and so on. Although biosensors have been around since glucose monitors were commercialized in the 1970s, the transition of laboratory research and innumerable research papers on biosensors into the world of commerce has lagged. There are several reasons for this phenomenon including the infamous “valley of death” afflicting entrepreneurs emerging from academic environment into the industrial world, where the rules for success can be radically different. In this context, musings on biosensors and especially nanobiosensors in an open access journal such as Journal of Biosensors and Bioelectronics is topical and appropriate especially since market surveys of biosensors are prohibitively expensive, sometimes running into thousands of dollars for a single copy. The contents and predictions of market share for biosensors in these reports also keep changing every time a report is published. Not only that, the market share projections for biosensors differs considerably amongst various reports. An editorial provides the opportunity to offer personal opinions and perhaps stimulate debate on a particular topic. In this sense, editorials are a departure from the rigor of a research paper. This editorial is no exception. With this preamble, it is worthwhile to stop and ponder the status of commercial biosensors and nanobiosensors.

The electrical power industry is facing the prospect of integrating a significant addition of variable generation technologies in the next several decades, primarily from wind and solar facilities. Overall, transmission and generation reserve levels are decreasing and power system infrastructure in general is aging. To maintain grid reliability modernization and expansion of the power system as well as more optimized use of existing resources will be required. Conventional and pumped storage hydroelectric facilities can provide an increasingly significant contribution to power system reliability by providing energy, capacity and other ancillary services. However, the potential role of hydroelectric power will be affected by another transition that the industry currently experiences - the evolution and expansion of electricity markets. This evolution to market-based acquisition of generation resources and grid management is taking place in a heterogeneous manner. Some North American regions are moving toward full-featured markets while other regions operate without formal markets. Yet other U.S. regions are partially evolved. This report examines the current structure of electric industry acquisition of energy and ancillary services in different regions organized along different structures, reports on the current role of hydroelectric facilities in various regions, and attempts to identify features of market and scheduling areas that either promote or thwart the increased role that hydroelectric power can play in the future. This report is part of a larger effort led by the Electric Power Research Institute with purpose of examining the potential for hydroelectric facilities to play a greater role in balancing the grid in an era of greater penetration of variable renewable energy technologies. Other topics that will be addressed in this larger effort include industry case studies of specific conventional and hydro-electric facilities, systemic operating constraints on hydro-electric resources, and production cost simulations aimed at quantifying the increased role of hydro.

Wind energy research activities at Sandia National Laboratories focus on developing large rotors that are lighter and more cost-effective than those designed with current technologies. Because gravity scales as the cube of the blade length, gravity loads become a constraining design factor for very large blades. Efforts to passively reduce turbulent loading has shown significant potential to reduce blade weight and capture more energy. Research in passive load reduction for wind turbines began at Sandia in the late 1990's and has moved from analytical studies to blade applications. This paper discusses the test results of two Sandia prototype research blades that incorporate load reduction techniques. The TX-100 is a 9-m long blade that induces bend-twist coupling with the use of off-axis carbon in the skin. The STAR blade is a 27-m long blade that induces bend-twist coupling by sweeping the blade in a geometric fashion.

We have observed the growth of monolayer graphene on Cu foils using low-energy electron microscopy. On the (100)-textured surface of the foils, four-lobed, 4-fold-symmetric islands nucleate and grow. The graphene in each of the four lobes has a different crystallographic alignment with respect to the underlying Cu substrate. These "polycrystalline" islands arise from complex heterogeneous nucleation events at surface imperfections. The shape evolution of the lobes is well explained by an angularly dependent growth velocity. Well-ordered graphene forms only above ∼790 °C. Sublimation-induced motion of Cu steps during growth at this temperature creates a rough surface, where large Cu mounds form under the graphene islands. Strategies for improving the quality of monolayer graphene grown on Cu foils must address these fundamental defect-generating processes. © 2010 American Chemical Society.

This article presents a generalized analysis on the significance of Galilean invariance in compressible flow computations with stabilized and variational multi-scale methods. The understanding of the key issues and the development of general approaches to Galilean-invariant stabilization are facilitated by the use of a matrix-operator description of Galilean transformations. The analysis of invariance for discontinuity capturing operators is also included. Published in 2010 by John Wiley & Sons, Ltd. This article is a U.S. Government work and is in the public domain in the U.S.A. Published in 2010 by John Wiley & Sons, Ltd.

The aerodynamic and acoustic performance of a Kevlar-walled anechoic wind tunnel test section has been analyzed. Aerodynamic measurements and panel method calculations were performed on a series of airfoils to reveal the influence of the test section walls, including their porosity and flexibility. A lift interference correction method was developed from first principles which shows consistently high accuracy when measurements are compared to viscous free-flight calculations. Interference corrections are an order of magnitude smaller than those associated with an open jet test section. Blockage corrections are found to be a fraction of those which would be associated with a hard-wall test section of the same size, and are negligible in most cases. New measurements showing the acoustic transparency of the Kevlar and the quality of the anechoic environment in the chambers are presented, along with benchmark trailing edge noise measurements. © 2010 by William J. Devenport, Ricardo A. Burdisso, Aurelien Borgoltz, Patricio Ravetta and Matthew F Barone.

Statistical analysis is typically used to reduce the dimensionality of and infer meaning from data. A key challenge of any statistical analysis package aimed at large-scale, distributed data is to address the orthogonal issues of parallel scalability and numerical stability. Many statistical techniques, e.g., descriptive statistics or principal component analysis, are based on moments and co-moments and, using robust online update formulas, can be computed in an embarrassingly parallel manner, amenable to a map-reduce style implementation. In this paper we focus on contingency tables, through which numerous derived statistics such as joint and marginal probability, point-wise mutual information, information entropy, and x2 independence statistics can be directly obtained. However, contingency tables can become large as data size increases, requiring a correspondingly large amount of communication between processors. This potential increase in communication prevents optimal parallel speedup and is the main difference with moment-based statistics (which we discussed in [1]) where the amount of inter-processor communication is independent of data size. Here we present the design trade-offs which we made to implement the computation of contingency tables in parallel.We also study the parallel speedup and scalability properties of our open source implementation. In particular, we observe optimal speed-up and scalability when the contingency statistics are used in their appropriate context, namely, when the data input is not quasi-diffuse. © 2010 IEEE.

Despite the many demonstrated applications of factor analysis (FA) in analyzing hyperspectral materials images, FA does have inherent mathematical limitations, preventing it from solving certain materials characterization problems. A notable limitation of FA is its parsimony restriction, referring to the fact that in FA the number of components cannot exceed the chemical rank of a dataset. Clustering is a promising alternative to FA for the phase classification of hyperspectral materials images. In contrast with FA, the phases extracted by clustering do not have to be parsimonious. Clustering has an added advantage in its insensitivity to spectral collinearity that can result in phase mixing using FA. For representative energy dispersive X-ray spectroscopy materials images, namely a solder bump dataset and a braze interface dataset, clustering generates phase classification results that are superior to those obtained using representative FA-based methods. For the solder bump dataset, clustering identifies a Cu-Sn intermetallic phase that cannot be isolated using FA alone due to the parsimony restriction. For the braze interface sample that has collinearity among the phase spectra, the clustering results do not exhibit the physically unrealistic phase mixing obtained by multivariate curve resolution, a commonly utilized FA algorithm. © Microscopy Society of America 2010.

Radiation sensing applications for SNM detection, identification, and characterization all face the same fundamental problem: each to varying degrees must infer the presence, identity, and configuration of a radiation source given a set of radiation signatures. This is a problem of inverse radiation transport: given the outcome of a measurement, what source terms and transport medium caused that observation? This paper presents a framework for solving inverse radiation transport problems, describes its essential components, and illustrates its features and performance. The framework implements an implicit solution to the inverse transport problem using deterministic neutron, electron, and photon transport calculations embedded in a Levenberg-Marquardt nonlinear optimization solver. The solver finds the layer thicknesses of a one-dimensional transport model by minimizing the difference between the gamma spectrum calculated by deterministic transport and the measured gamma spectrum. The fit to the measured spectrum is a full-spectrum analysisall spectral features are modeled, including photopeaks and continua from spontaneous and induced photon emissions. An example problem is solved by analyzing a high-resolution gamma spectrometry measurement of plutonium metal. © 2010 IEEE.

Thermoreflectance techniques are powerful tools for measuring thermophysical properties of thin film systems, such as thermal conductivity, Λ, of individual layers, or thermal boundary conductance across thin film interfaces (G). Thermoreflectance pump-probe experiments monitor the thermoreflectance change on the surface of a sample, which is related to the thermal properties in the sample of interest. Thermoreflectance setups have been designed with both continuous wave (cw) and pulsed laser systems. In cw systems, the phase of the heating event is monitored, and its response to the heating modulation frequency is related to the thermophysical properties; this technique is commonly termed a phase sensitive thermoreflectance (PSTR) technique. In pulsed laser systems, pump and probe pulses are temporally delayed relative to each other, and the decay in the thermoreflectance signal in response to the heating event is related to the thermophysical properties; this technique is commonly termed a transient thermoreflectance (TTR) technique. In this work, mathematical models are presented to be used with PSTR and TTR techniques to determine the Λ and G of thin films on substrate structures. The sensitivities of the models to various thermal and sample parameters are discussed, and the advantages and disadvantages of each technique are elucidated from the results of the model analyses. © 2010 Springer Science+Business Media, LLC.

Deformation bands in high porosity sandstone are an important geological feature for geologists and petroleum engineers; however, formation of these bands is not fully understood. The theoretical framework for deformation band formation in high porosity geomaterials is well established. It suggests that the intermediate principal stress influences the predicted deformation band type; however, these predictions have yet to be fully validated through experiments. Therefore, this study investigates the influence of the intermediate principal stress on failure and the formation of deformation bands in Castlegate sandstone. Mean stresses for these tests range from 30 to 150 MPa, covering brittle to ductile behavior. Deformation band orientations are measured with external observation as well as through acoustic emission locations. Results of experiments conducted at Lode angles of 30 and 14.5 degrees show trends that qualitatively agree with localization theory. The band angle (between the band normal and maximum compression) decreases with increasing mean stress. For tests at the same mean stress, band angle decreases with increasing Lode angle. Copyright 2010 ARMA, American Rock Mechanics Association.

This paper presents an integrated microfluidic system for selectively interrogating parallel biosensors at programmed time intervals. Specifically, the microfluidic system is used for delivering a volume of sample from a single source to a surface-based arrayed biosensor. In this case the biosensors were an array of electrochemical electrodes modified with sample specific capture probes. In addition, the sample was required to be captured, stored and removed for additional laboratory analysis. This was accomplished by a plastic laminate stack in which each thin laminate was patterned by CO2 laser ablation to form microchannels and two novel valves. The first valve was a normally closed type opened by heat via an electrically resistive wire. The second valve was a check type integrated into a removable storage chamber. This setup allows for remote and leave-behind sensing applications and also containment of sensed sample for further laboratory analysis. ©2010 IEEE.

Cooling with swirling jets is an effective means for enhancing heat transfer and improving spatial uniformity of the cooling rate in many applications. This paper investigates cooling a flat, isothermal plate at 1,000 K using a single and a triangular array of swirling air jets, and characterizes the resulting flow field and the air temperature above the plate. This problem was modeled using the Fuego computational fluid dynamics (CFD) code that is being developed at Sandia National Laboratories. The separation distance to jet diameter, L/D, varied from 3 to 12, Reynolds number, Re, varied from 5×103-5×104, and the swirl number, S varied from 0 to 2.49. The formation of the central recirculation zone (CRZ) and its impact on heat transfer were also investigated. For a hubless swirling jet, a CRZ was generated whenever S ≥ 0.67, in agreement with experimental data and our mathematical derivation for swirl (helicoid) azimuthal and axial velocities. On the other hand, for S <0.058, the velocity field closely approximated that of a conventional jet. With the azimuthal velocity of a swirling jet decaying as 1/z2, most mixing occurred only a few jet diameters from the jet nozzle. Highest cooling occurred when L/D = 3 and S = 0.12 to 0.79. Heat transfer enhancement increased as S or Re increased, or L/D decreased. © 2010 by ASME.

The transient response of Silicon Carbide (SiC) Metal-Oxide-Semiconductor Field Effect Transistors (MOSFETs) with three different gates due to a single ion strike is studied. Comparing the experiment and numerical simulation, it is suggested that the charge enhancement is due to the bipolar effect. We find the bipolar gain depends on the quality of gate oxide. The impact of fixed charge in SiO2 and interface traps at SiC/SiO2 on the charge collection is discussed. © 2010 IEEE.

Dielectric resonators are an effective means to realize isotropic, low-loss optical metamaterials. As proof of this concept, a cubic resonator is analytically designed and then tested in the long-wave infrared. © 2010 Optical Society of America.

An ultra-compact optical true time delay device is demonstrated that can support 112 antenna elements with better than six bits of delay in a volume 16″x5″x4″ including the box and electronics. Free-space beams circulate in a White cell, overlapping in space to minimize volume. The 18 mirrors are slow-tool diamond turned on two substrates, one at each end, to streamline alignment. Pointing accuracy of better than 10?rad is achieved, with surface roughness ∼45 nm rms. A MEMS tip-style mirror array selects among the paths for each beam independently, requiring ∼100 μs to switch the whole array. The micromirrors have 1.4° tip angle and three stable states (east, west, and flat). The input is a fiber-andmicrolens array, whose output spots are re-imaged multiple times in the White cell, striking a different area of the single MEMS chip in each of 10 bounces. The output is converted to RF by an integrated InP wideband optical combiner detector array. Delays were accurate to within 4% (shortest delay) to 0.03% (longest mirror train). The fiber-to- detector insertion loss is 7.82 dB for the shortest delay path. © 2010 SPIE.

Modern space based optical sensors place substantial demands on the focal plane array readout integrated circuit. Active pixel readout designs offer direct access to individual pixel data but require analog to digital conversion at or near each pixel. Thus, circuit designers must create precise, fundamentally analog circuitry within tightly constrained areas on the integrated circuit. Rapidly changing phenomena necessitate tradeoffs between sampling and conversion speed, data precision, and heat generation adjacent the detector array, especially of concern for thermally sensitive space grade infrared detectors. A simplified parametric model is presented that illustrates seeker system performance and analog to digital conversion requirements trends in the visible through mid-wave infrared, for varying sample rate. Notional limiting-case Earth optical backgrounds were generated using MODTRAN4 with a range of cloud extremes and approximate practical albedo limits for typical surface features from a composite of the Mosart and Aster spectral albedo databases. The dynamic range requirements imposed by these background spectra are discussed in the context of optical band selection and readout design impacts. © 2010 Copyright SPIE - The International Society for Optical Engineering.

Generating circular polarization for ultra-intense lasers requires solutions beyond traditional transmissive waveplates which have insufficient bandwidth and pose nonlinear phase (B-integral) problems. We demonstrate a reflective design employing 3 metallic mirrors to gen-erate circular polarization. © 2010 Optical Society of America.

The Explosive Destruction System (EDS) was developed by Sandia National Laboratories for the US Army Product Manager for Non-Stockpile Chemical Materiel (PMNSCM) to destroy recovered, explosively configured, chemical munitions. PMNSCM currently has five EDS units that have processed over 1,400 items. The system uses linear and conical shaped charges to open munitions and attack the burster followed by chemical treatment of the agent. The main component of the EDS is a stainless steel, cylindrical vessel, which contains the explosion and the subsequent chemical treatment. Extensive modeling and testing have been used to design and qualify the vessel for different applications and conditions. The high explosive (HE) pressure histories and subsequent vessel response (strain histories) are modeled using the analysis codes CTH and LS-DYNA, respectively. Using the model results, a load rating for the EDS is determined based on design guidance provided in the ASME Code, Sect. VIII, Div. 3, Code Case No. 2564. One of the goals is to assess and understand the vessel's capacity in containing a wide variety of detonation sequences at various load levels. Of particular interest are to know the total number of detonation events at the rated load that can be processed inside each vessel, and a maximum load (such as that arising from an upset condition) that can be contained without causing catastrophic failure of the vessel. This paper will discuss application of Code Case 2564 to the stainless steel EDS vessels, including a fatigue analysis using a J-R curve, vessel response to extreme upset loads, and the effects of strain hardening from successive events. Copyright © 2010 by ASME.

We demonstrate an optical gate architecture with optical isolation between input and output using interconnected PD-EAMs to perform AND and NOT functions. Waveforms for 10 Gbps AND and 40 Gbps NOT gates are shown. © 2010 Optical Society of America.

Beamforming is a methodology for collection-mode-independent SAR image formation. It is essentially equivalent to backprojection. The authors have in previous papers developed this idea and discussed the advantages and disadvantages of the approach to monostatic SAR image formation vis-à-vis the more standard and time-tested polar formatting algorithm (PFA). In this paper we show that beamforming for bistatic SAR imaging leads again to a very simple image formation algorithm that requires a minimal number of lines of code and that allows the image to be directly formed onto a three-dimensional surface model, thus automatically creating an orthorectified image. The same disadvantage of beamforming applied to monostatic SAR imaging applies to the bistatic case, however, in that the execution time for the beamforming algorithm is quite long compared to that of PFA. Fast versions of beamforming do exist to help alleviate this issue. Results of image reconstructions from phase history data are presented. © 2010 Copyright SPIE - The International Society for Optical Engineering.

We have demonstrated the ability to control the microstructure of PETN films deposited using physical vapor deposition by altering the interface between the film and substrate. Evolution of surface morphology, average density, and surface roughness with film thickness were characterized using surface profilometry and scanning electron microscopy. While films on all of the substrates investigated showed a trend toward a lower average density with increasing film thickness, there were significant variations in density, pore size, and surface morphology in films deposited on different substrates.

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Density Functional Theory (DFT) has over the last few years emerged as an indispensable tool for understanding the behavior of matter under extreme conditions. DFT based molecular dynamics simulations (MD) have for example confirmed experimental findings for shocked deuterium,1 enabled the first experimental evidence for a triple point in carbon above 850 GPa,2 and amended experimental data for constructing a global equation of state (EOS) for water, carrying implications for planetary physics.3 The ability to perform high-fidelity calculations is even more important for cases where experiments are impossible to perform, dangerous, and/or prohibitively expensive. For solid explosives, and other molecular crystals, similar success has been severely hampered by an inability of describing the materials at equilibrium. The binding mechanism of molecular crystals (van der Waals' forces) is not well described within traditional DFT.4 Among widely used exchange-correlation functionals, neither LDA nor PBE balances the strong intra-molecular chemical bonding and the weak inter-molecular attraction, resulting in incorrect equilibrium density, negatively affecting the construction of EOS for undetonated high explosives. We are exploring a way of bypassing this problem by using the new Armiento-Mattsson 2005 (AM05) exchange-correlation functional.5, 6 The AM05 functional is highly accurate for a wide range of solids,4, 7 in particular in compression.8 In addition, AM05 does not include any van der Waals' attraction,4 which can be advantageous compared to other functionals: Correcting for a fictitious van der Waals' like attraction with unknown origin can be harder than correcting for a complete absence of all types of van der Waals' attraction. We will show examples from other materials systems where van der Waals' attraction plays a key role, where this scheme has worked well,9 and discuss preliminary results for molecular crystals and explosives.

Decision-makers want to perform risk-based cost-benefit prioritization of security investments. However, strong nonlinearities in the most common physical security performance metric make it difficult to use for cost-benefit analysis. This paper extends the definition of risk for security applications and embodies this definition in a new but related security risk metric based on the degree of difficulty an adversary will encounter to successfully execute the most advantageous attack scenario. This metric is compatible with traditional cost-benefit optimization algorithms, and can lead to an objective risk-based cost-benefit method for security investment option prioritization. It also enables decision-makers to more effectively communicate the justification for their investment decisions with stakeholders and funding authorities. ©2010 IEEE.

Material control and accounting (MC&A) safeguards operations that track and account for critical assets at nuclear facilities provide a key protection approach for defeating insider adversaries. These activities, however, have been difficult to characterize in ways that are compatible with the probabilistic path analysis methods that are used to systematically evaluate the effectiveness of a site's physical protection (security) system (PPS). MC&A activities have many similar characteristics to operator procedures performed in a nuclear power plant (NPP) to check for anomalous conditions. This work applies human reliability analysis (HRA) methods and models for human performance of NPP operations to develop detection probabilities for MC&A activities. This has enabled the development of an extended probabilistic path analysis methodology in which MC&A protections can be combined with traditional sensor data in the calculation of PPS effectiveness. The extended path analysis methodology provides an integrated evaluation of a safeguards and security system that addresses its effectiveness for attacks by both outside and inside adversaries.

Compaction waves in porous energetic materials have been shown to induce reaction under impact loading. In the past, simple two-state burn models such as the Arrhenius Burn model have been developed to predict slapper initiation in Hexanitrostilbene (HNS) pellets; however, a more sophisticated, fundamental approach is needed to predict the shock response during impact loading, especially in pellets that have been shown to have strong density gradients. The intergranular stress measures the resistance to bed compaction or the removal of void space due to particle packing and rearrangement. A constitutive model for the intergranular stress is needed for closure in the Baer-Nunziato (BN) multiphase mixture theory for reactive energetic materials. The intergranular stress was obtained from both quasi-static compaction experiments and from dynamic compaction experiments. Additionally, historical data and more recently acquired data for porous pellets compacted to high densities under shock loading were used for model assessment. Predicted particle velocity profiles under dynamic compaction were generally in good agreement with the experimental data. Hence, a multiphase model of HNS has been developed to extend current predictive capability.

In the International HRA Empirical Study, human reliability analysis (HRA) method predictions for human failure events (HFEs) in steam generator tube rupture and loss of feedwater scenarios were compared against the performance of real crews in a nuclear power plant control room simulator. The comparisons examined both the qualitative and quantitative HRA method predictions. This paper discusses some of the lessons learned about HRA methods that have been identified to date. General strengths and weaknesses of HRA methods are addressed, along with the reasons for any limitations in the predictive results produced by the methods. However, the discussions of the lessons learned in this paper must be considered a "snapshot." While most of the data has been analyzed, more detailed analysis of the results from specific HRA methods are ongoing and additional information may emerge.

This paper derives a methodology to enable spatial and temporal control of thermally inhomogeneous molecular dynamics (MD) simulations. The primary goal is to perform non-equilibrium MD of thermal transport analogous to continuum solutions of heat flow which have complex initial and boundary conditions, moving MD beyond quasi-equilibrium simulations using periodic boundary conditions. In our paradigm, the entire spatial domain is filled with atoms and overlaid with a finite element (FE) mesh. The representation of continuous variables on this mesh allows fixed temperature and fixed heat flux boundary conditions to be applied, non-equilibrium initial conditions to be imposed and source terms to be added to the atomistic system. In effect, the FE mesh defines a large length scale over which atomic quantities can be locally averaged to derive continuous fields. Unlike coupling methods which require a surrogate model of thermal transport like Fourier's law, in this work the FE grid is only employed for its projection, averaging and interpolation properties. Inherent in this approach is the assumption that MD observables of interest, e.g. temperature, can be mapped to a continuous representation in a non-equilibrium setting. This assumption is taken advantage of to derive a single, unified set of control forces based on Gaussian isokinetic thermostats to regulate the temperature and heat flux locally in the MD. Example problems are used to illustrate potential applications. In addition to the physical results, data relevant to understanding the numerical effects of the method on these systems are also presented. © 2010 IOP Publishing Ltd.

In the preceding discussion paper, I proposed a theory of prefrontal cortical organization that was fundamentally intended to address the question: How does prefrontal cortex (PFC) support the various functions for which it seems to be selectively recruited? In so doing, I chose to focus on a particular function, analogy, that seems to have been largely ignored in the theoretical treatments of PFC, but that does underlie many other cognitive functions (Hofstadter, 2001; Holyoak & Thagard, 1997). At its core, this paper was intended to use analogy as a foundation for exploring one possibility for prefrontal function in general, although it is easy to see how the analogy-specific interpretation arises (as in the comment by Ibáñez). In an attempt to address this more foundational question, this response will step away from analogy as a focus, and will address first the various comments from the perspective of the initial motivation for developing this theory, and then specific issues raised by the commentators. © 2010 Psychology Press.

The U.S. Nuclear Regulatory Commission, in concert with industry, continues to explore the effects of fire on electrical cable and control circuit performance. The latest efforts, which are currently underway, are exploring issues related to fire-induced cable failure modes and effects for direct current (dc) powered electrical control circuits. An extensive series of small and intermediate scale fire tests has been performed. Each test induced electrical failure in copper conductor cables of various types typical of those used by the U.S. commercial nuclear power industry. The cables in each test were connected to one of several surrogate dc control circuits designed to monitor and detect cable electrical failure modes and effects. The tested dc control circuits included two sets of reversing dc motor starters typical of those used in motor-operated valve (MOV) circuits, two small solenoid-operated valves (SOV), one intermediate size (1-inch (25.4mm) diameter) SOV, a very large direct-acting valve coil, and a switchgear/breaker unit. Also included was a specialized test circuit designed specifically to monitor for electrical shorts between two cables (inter-cable shorting). Each of these circuits was powered from a nominal 125V battery bank comprised of 60 individual battery cells (nominal 2V lead-acid type cells with plates made from a lead-cadmium alloy). The total available short circuit current at the terminals of the battery bank was estimated at 13,000A. All of the planned tests have been completed with the data analysis and reporting currently being completed. This paper will briefly describe the test program, some of the preliminary test insights, and planned follow-on activities.

In this paper we demonstrate the potential for novel nanoporous framework materials (NFM) such as metal-organic frameworks (MOFs) to provide selectivity and sensitivity to a broad range of analytes including explosives, nerve agents, and volatile organic compounds (VOCs). NFM are highly ordered, crystalline materials with considerable synthetic flexibility resulting from the presence of both organic and inorganic components within their structure. Detection of chemical weapons of mass destruction (CWMD), explosives, toxic industrial chemicals (TICs), and volatile organic compounds (VOCs) using micro-electro-mechanical-systems (MEMS) devices, such as microcantilevers and surface acoustic wave sensors, requires the use of recognition layers to impart selectivity. Traditional organic polymers are dense, impeding analyte uptake and slowing sensor response. The nanoporosity and ultrahigh surface areas of NFM enhance transport into and out of the NFM layer, improving response times, and their ordered structure enables structural tuning to impart selectivity. Here we describe experiments and modeling aimed at creating NFM layers tailored to the detection of water vapor, explosives, CWMD, and VOCs, and their integration with the surfaces of MEMS devices. Force field models show that a high degree of chemical selectivity is feasible. For example, using a suite of MOFs it should be possible to select for explosives vs. CWMD, VM vs. GA (nerve agents), and anthracene vs. naphthalene (VOCs). We will also demonstrate the integration of various NFM with the surfaces of MEMS devices and describe new synthetic methods developed to improve the quality of VFM coatings. Finally, MOF-coated MEMS devices show how temperature changes can be tuned to improve response times, selectivity, and sensitivity. © 2010 Copyright SPIE - The International Society for Optical Engineering.

We present the design, fabrication, and characterization of a pixelated, hyperspectral arrayed component for Focal Plane Array (FPA) integration in the Long-Wave IR. This device contains tens of pixels within a single super-pixel which is tiled across the extent of the FPA. Each spectral pixel maps to a single FPA pixel with a spectral FWHM of 200nm. With this arrayed approach, remote sensing data may be accumulated with a non-scanning, "snapshot" imaging system. This technology is flexible with respect to individual pixel center wavelength and to pixel position within the array. Moreover, the entire pixel area has a single wavelength response, not the integrated linear response of a graded cavity thickness design. These requirements bar tilted, linear array technologies where the cavity length monotonically increases across the device. © 2010 Copyright SPIE - The International Society for Optical Engineering.

Modern space based optical sensors place substantial demands on the focal plane array readout integrated circuit. Active pixel readout designs offer direct access to individual pixel data but require analog to digital conversion at or near each pixel. Thus, circuit designers must create precise, fundamentally analog circuitry within tightly constrained areas on the integrated circuit. Rapidly changing phenomena necessitate tradeoffs between sampling and conversion speed, data precision, and heat generation adjacent the detector array, especially of concern for thermally sensitive space grade infrared detectors. A simplified parametric model is presented that illustrates seeker system performance and analog to digital conversion requirements trends in the visible through mid-wave infrared, for varying sample rate. Notional limiting-case Earth optical backgrounds were generated using MODTRAN4 with a range of cloud extremes and approximate practical albedo limits for typical surface features from a composite of the Mosart and Aster spectral albedo databases. The dynamic range requirements imposed by these background spectra are discussed in the context of optical band selection and readout design impacts. © 2010 Copyright SPIE - The International Society for Optical Engineering.

For the purpose of simulating the effects of neutron radiation damage on bipolar circuit performance, a bipolar junction transistor (BJT) compact model incorporating displacement damage effects and rapid annealing has been developed. A physics-based approach is used to model displacement damage effects, and this modeling approach is implemented as an augmentation to the Gummel-Poon BJT model. The model is presented and implemented in the Xyce circuit simulator, and is shown to agree well with experiments and TCAD simulation, and is shown to be superior to a previous compact modeling approach. © 2010 IEEE.

Biomolecular simulations have traditionally benefited from increases in the processor clock speed and coarse-grain inter-node parallelism on large-scale clusters. With stagnating clock frequencies, the evolutionary path for performance of microprocessors is maintained by virtue of core multiplication. Graphical processing units (GPUs) offer revolutionary performance potential at the cost of increased programming complexity. Furthermore, it has been extremely challenging to effectively utilize heterogeneous resources (host processor and GPU cores) for scientific simulations, as underlying systems, programming models and tools are continually evolving. In this paper, we present a parametric study demonstrating approaches to exploit resources of heterogeneous systems to reduce time-to-solution of a production-level application for biological simulations. By overlapping and pipelining computation and communication, we observe up to 10-fold application acceleration in multi-core and multi-GPU environments illustrating significant performance improvements over code acceleration approaches, where the host-to-accelerator ratio is static, and is constrained by a given algorithmic implementation. © 2010 IEEE.

Dish concentrators can produce highly concentrated flux for the operation of an engine, a chemical process, or other energy converter. The high concentration allows a small aperture to control thermal losses, and permits high temperature processes at the focal point. A variety of optical errors can influence the flux pattern both at the aperture and at the absorber surface. Impacts of these errors can be lost energy (intercept losses), aperture compromise (increased size to accommodate flux), high peak fluxes (leading to part failure or life reduction), and improperly positioned flux also leading to component failure. Optical errors can include small scale facet errors ("waviness"), facet shape errors, alignment (facet pointing) errors, structural deflections, and tracking errors. The errors may be random in nature, or may be systematic. The various sources of errors are often combined in a "root-mean-squared" process to present a single number as an "error budget". However, this approach ignores the fact that various errors can influence the performance in different ways, and can mislead the designer, leading to component damage in a system or poor system performance. In this paper, we model a hypothetical radial gore dish system using Sandia's CIRCE2 optical code. We evaluate the peak flux and incident power through the aperture and onto various parts of the receiver cavity. We explore the impact of different error sources on the character of the flux pattern, and demonstrate the limitations of lumping all of the errors into a single error budget. © 2010 by ASME.

The International Human Reliability Analysis (HRA) Empirical Study is a comparative benchmark of the prediction of HRA methods to the performance of nuclear power plant crews in a control room simulator. There are a number of unique aspects to the present study that distinguish it from previous HRA benchmarks, most notably the emphasis on a method-to-data comparison instead of a method-to-method comparison. This paper reviews seven lessons learned about HRA benchmarking from conducting the study: (1) the dual purposes of the study afforded by joining another HRA study; (2) the importance of comparing not only quantitative but also qualitative aspects of HRA; (3) consideration of both negative and positive drivers on crew performance; (4) a relatively large sample size of crews; (5) the use of multiple methods and scenarios to provide a well-rounded view of HRA performance; (6) the importance of clearly defined human failure events; and (7) the use of a common comparison language to "translate" the results of different HRA methods. These seven lessons learned highlight how the present study can serve as a useful template for future benchmarking studies.

In the International HRA Empirical Study, diverse Human Reliability Analysis (HRA) methods are assessed based on data from a dedicated simulator study, which examined the performance of licensed crews in nuclear power plant emergency scenarios. The HRA method assessments involve comparing the predictions obtained with the method with empirical reference data, in quantitative as well as qualitative terms. This paper discusses the assessment approach and criteria, the quantitative reference data, and the comparisons that use these data. Consistent with the expectations at the outset of the study, the statistical limitations of the data are a key issue. These limitations preclude concentrating solely on the failure counts defined by the Human Failure Event (HFE) success criteria and the failure probabilities based on these counts. In assessing quantitative predictive power, this study additionally uses a reference HFE difficulty (qualitative failure likelihood) ranking that accounts for qualitative observations in addition to the failure counts. Overall, the method assessment prioritizes qualitative comparisons, using the rich set of data collected on performance issues. Here, the quantitative predictions and data are used to determine the essential qualitative comparisons, demonstrating how quantitative and qualitative comparisons and criteria can be usefully combined in HRA method assessment.

The Office of Nuclear Regulatory Research (RES) of the U.S. Nuclear Regulatory Commission is sponsoring work in response to a Staff Requirements Memorandum (SRM) directing an effort to establish a single human reliability analysis (HRA) method for the agency or guidance for the use of multiple methods. One motivation is the variability in Human Failure Event (HFE) probabilities estimated by different analysts and methods. This work considers that a reduction of the variability in the HRA quantification outputs must address three sources: differences in the scope and implementation of qualitative analysis, the qualitative output-quantitative input interface, and the diversity of algorithms for estimating failure probabilities from these inputs. Two companion papers (Mosleh et al. and Hendrickson et al.) describe a proposed qualitative analysis approach The development of the corresponding quantification approach considers a number of alternatives including a module-based hybrid method and a data-driven quantification scheme. This paper presents on-going work and the views of the contributors.

Polymer foam encapsulants provide mechanical, electrical, and thermal isolation in engineered systems. In fire environments, foams, such as polyurethanes, can liquefy and flow during thermal decomposition, and evolved gases and vapors can cause pressurization and failure of sealed containers. Liquefaction and flow of decomposing foam can cause serious modeling issues in systems safety and hazard analyses. To mitigate the issues resulting from liquefaction and flow, a hybrid polyurethane-cyanate-ester-epoxy foam was developed that has mechanical properties similar to currently used polyurethane foams. The hybrid foam behaves predictably, does not liquefy, and forms 40-50 percent by weight uniform char during decomposition in nitrogen. The char forms predictably and is a relatively uniform "participating medium." A previous paper discussed the experimental and modeling approach developed to predict radiation and conduction heat transfer through decomposing hybrid foam in vented containers. This paper discusses application of a similar approach to the more difficult problem of predicting heat transfer, foam decomposition, and pressure growth in sealed containers. Model predictions are compared with results from radiant heat transfer experiments involving foam encapsulated objects in sealed containers. All model parameters were evaluated from independent laboratory-scale experiments such as TGA and DSC. The time dependent-pressure in the container and the timedependent temperature near the surface of a foam-encapsulated object agreed well with experimental data. © (2010) by BCC Research All rights reserved.

Cyber security analysis tools are necessary to evaluate the security, reliability, and resilience of networked information systems against cyber attack. It is common practice in modern cyber security analysis to separately utilize real systems computers, routers, switches, firewalls, computer emulations (e.g., virtual machines) and simulation models to analyze the interplay between cyber threats and safeguards. In contrast, Sandia National Laboratories has developed new methods to combine these evaluation platforms into a cyber Live, Virtual, and Constructive (LVC) testbed. The combination of real, emulated, and simulated components enables the analysis of security features and components of a networked information system. When performing cyber security analysis on a target system, it is critical to represent realistically the subject security components in high fidelity. In some experiments, the security component may be the actual hardware and software with all the surrounding components represented in simulation or with surrogate devices. Sandia National Laboratories has developed a cyber LVC testbed that combines modeling and simulation capabilities with virtual machines and real devices to represent, in varying fidelity, secure networked information system architectures and devices. Using this capability, secure networked information system architectures can be represented in our testbed on a single computing platform. This provides an "experiment-in-a-box" capability. The result is rapidly produced, large scale, relatively low-cost, multi-fidelity representations of networked information systems. These representations enable analysts to quickly investigate cyber threats and test protection approaches and configurations.

The launch of nuclear materials requires special care to minimize the risk of adverse effects to human health and the environment. This paper describes the special sources of risk that are inherent to the launch of radioactive materials and provides insights into the analysis and control of these risks that have been gained through the experience of previous US launches. Historically, launch safety has been achieved by eliminating, to the greatest degree possible, the potential for energetic insults to affect the radioactive material. For those insults that cannot be precluded, designers minimize the likelihood, magnitude and duration of their interaction with the material. Finally, when a radioactive release cannot be precluded, designers limit the magnitude and spatial extent of its dispersal.

We investigate the efficacy of mitigating radiation-based single event effects (SEE) within circuits incorporating SiGe heterojunction bipolar transistors (HBTs) built with an N-Ring, a transistor-level layout-based radiation hardened by design (RHBD) technique. Previous work of single-device ion-beam induced charge collection (IBICC) studies has demonstrated significant reductions in peak collector charge collection and sensitive area for charge collection; however, few circuit studies using this technique have been performed. Transient studies performed with Sandia National Laboratory's (SNL) 36 MeV 16O microbeam on voltage references built with N-Ring SiGe HBTs have shown mixed results, with reductions in the number of large voltage disruptions in addition to new sensitive areas of low-level output voltage disturbances. Similar discrepancies between device-level IBICC results and circuit measurements are found for the case of digital shift registers implemented with N-Ring SiGe HBTs irradiated in a broadbeam environment at Texas A&M's Cyclotron Institute. The error cross-section curve of the N-Ring based register is found to be larger at larger ion LETs than the standard SiGe register, which is clearly counter-intuitive. We have worked to resolve the discrepancy between the measured circuit results and the device-level IBICC measurements, by re-measuring single-device N-Ring SiGe HBTs using a time-resolved ion beam induced charge (TRIBIC) set-up that allows direct capture of nodal transients. Coupling these measurements with full 3-D TCAD simulations provides complete insight into the origin of transient currents in an N-Ring SiGe HBT. The detailed structure of these transients and their bias dependencies are discussed, together with the ramifications for the design of space-borne analog and digital circuits using SiGe HBTs. © 2010 IEEE.

Understanding the effects of gravity and wind loads on concentrating solar power (CSP) collectors is critical for performance calculations and developing more accurate alignment procedures and techniques. This paper presents a rigorous finite-element model of a parabolic trough collector that is used to determine the impact of gravity loads on bending and displacements of the mirror facets and support structure. The geometry of the LUZ LS-2 parabolic trough collector was modeled using SolidWorks, and gravity-induced loading and displacements were simulated in SolidWorks Simulation. The model of the trough collector was evaluated in two positions: the 90° position (mirrors facing upward) and the 0° position (mirrors facing horizontally). The slope errors of the mirror facet reflective surfaces were found by evaluating simulated angular displacements of node-connected segments along the mirror surface. The ideal (undeformed) shape of the mirror was compared to the shape of the deformed mirror after gravity loading. Also, slope errors were obtained by comparing the deformed shapes between the 90° and 0° positions. The slope errors resulting from comparison between the deformed vs. undeformed shape were as high as ∼2 mrad, depending on the location of the mirror facet on the collector. The slope errors resulting from a change in orientation of the trough from the 90° position to the 0° position with gravity loading were as high as ∼3 mrad, depending on the location of the facet. © 2010 by ASME.

A general-purpose algorithm for mesh optimization via node-movement, known as the Target-Matrix Paradigm, is introduced. The algorithm is general purpose in that it can be applied to a wide variety of mesh and element types, and to various commonly recurring mesh optimization problems such as shape improvement, and to more unusual problems like boundary-layer preservation with sliver removal, high-order mesh improvement, and edge-length equalization. The algorithm can be considered to be a direct optimization method in which weights are automatically constructed to enable definitions of application-specific mesh quality. The high-level concepts of the paradigm have been implemented in the Mesquite mesh-improvement library, along with a number of concrete algorithms that address mesh quality issues such as those shown in the examples of the present paper. © 2010 Springer-Verlag Berlin Heidelberg.

Diesel spray experimentation at controlled high-temperature and high-pressure conditions is intended to provide a more fundamental understanding of diesel combustion than can be achieved in engine experiments. This level of understanding is needed to develop the high-fidelity multi-scale CFD models that will be used to optimize future engine designs. Several spray chamber facilities capable of high-temperature, high-pressure conditions typical of engine combustion have been developed, but because of the uniqueness of each facility, there are uncertainties about their operation. For this paper, we describe results from comparative studies using constant-volume vessels at Sandia National Laboratories and IFP. Targeting the same ambient gas conditions (900 K, 60 bar, 22.8 kg/m 3, 15% oxygen) and using the same injector specifications (common rail, 1500 bar, KS 1.5/86 nozzle, 0.090 mm orifice diameter, n-dodecane, 363 K), we describe detailed measurements of the temperature and pressure boundary conditions at each facility, followed by observations of spray penetration, ignition, and combustion using high-speed imaging. The spray diagnostics show reasonable similarity despite the challenges of providing matched boundary conditions at these unique facilities. Performing experiments at the same high-temperature, highpressure operating conditions is an objective of the Engine Combustion Network (), which seeks to leverage the research capabilities and advanced diagnostics of all participants in the ECN. Thus, in addition to the presentation of a comparative study, this paper demonstrates steps that are needed for other interested groups to participate in ECN spray research. We expect that this collaborative effort will generate a high-quality dataset to be used for advanced computational model development at engine conditions. © 2010 SAE International.

Human Reliability Analysis (HRA) methods have been developed primarily to provide information for use in probabilistic risk assessments analyzing nuclear power plant (NPP) operations. Despite this historical focus on the control room, there has been growing interest in applying HRA methods to other NPP activities such as dry cask storage operations (DCSOs) in which spent fuel is transferred into dry cask storage systems. This paper describes a successful application of aspects of the "A Technique for Human Event Analysis" (ATHEANA) HRA approach [1, 2] in performing qualitative HRA activities that generated insights on the potential for dropping a spent fuel cask during DCSOs. This paper provides a description of the process followed during the analysis, a description of the human failure event (HFE) scenario groupings, discussion of inferred human performance vulnerabilities, a detailed examination of one HFE scenario and illustrative approaches for avoiding or mitigating human performance vulnerabilities that may contribute to dropping a spent fuel cask.

In May 2007, Forest City Military Communities won a US Department of Energy Solar America Showcase Award. As part of this award, executives and staff from Forest City Military Communities worked side-by-side with a DOE technical assistance team to overcome technical obstacles encountered by this large-scale real estate developer and manager. This paper describes the solar technical assistance that was provided and the key solar experiences acquired by Forest City Military Communities over an 18 month period.

The Department of Energy's 2008 Yucca Mountain Performance Assessment represents the culmination of more than two decades of analyses of post-closure repository performance in support of programmatic decision making for the proposed Yucca Mountain repository. The 2008 performance assessment summarizes the estimated long-term risks to the health and safety of the public resulting from disposal of spent nuclear fuel and high-level radioactive waste in the proposed Yucca Mountain repository. The standards at 10 CFR Part 63 request several numerical estimates quantifying performance of the repository over time. This paper summarizes the key quantitative results from the performance assessment and presents uncertainty and sensitivity analyses for these results.

We discuss and verify experimentally the design of a 1-D planar periodic combline leaky-wave antenna that avoids the open-stopband effects as the beam is scanned through broadside. ©2010 IEEE.

A tandem interferometer system measuring the absolute phase and amplitude of planar split-ring resonators fabricated on a BaF2 substrate with a designed resonance at 10.5 μm is presented. © 2010 Optical Society of America.

This paper presents a mixed-potential integral-equation formulation for analyzing 1-D periodic leaky-wave antennas in layered media. The structures are periodic in one dimension and finite in the other two dimensions. The unit cell consists of an arbitrary-shaped metallic/dielectric structure. The formulation has been implemented in the EIGER™ code in order to obtain the real and complex propagation wavenumbers of the bound and leaky modes of such structures. Validation results presented here include a 1-D periodic planar leaky-wave antenna and a fully 3-D waveguide test case. ©2010 IEEE.

The complexity of physical protection systems has increased to address modern threats to national security and emerging commercial technologies. A key element of modern physical protection systems is the data presented to the human operator used for rapid determination of the cause of an alarm, whether false (e.g., caused by an animal, debris, etc.) or real (e.g., a human adversary). Alarm assessment (the human validation of a sensor alarm) primarily relies on imaging technologies and video systems. Developing measures of effectiveness (MOE) that drive the design or evaluation of a video system or technology becomes a challenge, given the subjectivity of the application (e.g., alarm assessment). Sandia National Laboratories has conducted empirical analysis using field test data and mathematical models such as binomial distribution and Johnson target transfer functions to develop MOEs for video system technologies. Depending on the technology, the task of the security operator and the distance to the target, the Probability of Assessment (PAs) can be determined as a function of a variety of conditions or assumptions. PAs used as an MOE allows the systems engineer to conduct trade studies, make informed design decisions, or evaluate new higher-risk technologies. This paper outlines general video system design trade-offs, discusses ways video can be used to increase system performance, and lists MOEs for video systems used in subjective applications such as alarm assessment. ©2010 IEEE.

We present an RDFS closure algorithm, specifically designed and implemented on the Cray XMT supercomputer, that obtains inference rates of 13 million inferences per second on the largest system configuration we used. The Cray XMT, with its large global memory (4TB for our experiments), permits the construction of a conceptually straightforward algorithm, fundamentally a series of operations on a shared hash table. Each thread is given a partition of triple data to process, a dedicated copy of the ontology to apply to the data, and a reference to the hash table into which it inserts inferred triples. The global nature of the hash table allows the algorithm to avoid a common obstacle for distributed memory machines: the creation of duplicate triples. On LUBM data sets ranging between 1.3 billion and 5.3 billion triples, we obtain nearly linear speedup except for two portions: file I/O, which can be ameliorated with the additional service nodes, and data structure initialization, which requires nearly constant time for runs involving 32 processors or more.

Energy network optimization (ENO) models identify new strategies for designing, installing, and controlling stationary combined heat and power (CHP) fuel cell systems (FCSs) with the goals of 1) minimizing electricity and heating costs for building owners and 2) reducing emissions of the primary greenhouse gas (GHG) - carbon dioxide (CO2). A goal of this work is to employ relatively inexpensive simulation studies to discover more financially and environmentally effective approaches for installing CHP FCSs. ENO models quantify the impact of different choices made by power generation operators, FCS manufacturers, building owners, and governments with respect to two primary goals - energy cost savings for building owners and CO2 emission reductions. These types of models are crucial for identifying cost and CO 2 optima for particular installations. Optimal strategies change with varying economic and environmental conditions, FCS performance, the characteristics of building demand for electricity and heat, and many other factors. ENO models evaluate both "business-as-usual" and novel FCS operating strategies. For the scenarios examined here, relative to a base case of no FCSs installed, model results indicate that novel strategies could reduce building energy costs by 25% and CO2 emissions by 80%. Part I of II articles discusses model assumptions and methodology. Part II of II articles illustrates model results for a university campus town and generalizes these results for diverse communities. Copyright © 2010 by ASME.

Innovative energy system optimization models are deployed to evaluate novel fuel cell system (FCS) operating strategies, not typically pursued by commercial industry. Most FCS today are installed according to a 'business-as-usual' approach: (1) stand-alone (unconnected to district heating networks and low-voltage electricity distribution lines), (2) not load following (not producing output equivalent to the instantaneous electrical or thermal demand of surrounding buildings), (3) employing a fairly fixed heat-to-power ratio (producing heat and electricity in a relatively constant ratio to each other), and (4) producing only electricity and no recoverable heat. By contrast, models discussed here consider novel approaches as well. Novel approaches include (1) networking (connecting FCSs to electrical and/or thermal networks), (2) load following (having FCSs produce only the instantaneous electricity or heat demanded by surrounding buildings), (3) employing a variable heat-to-power ratio (such that FCS can vary the ratio of heat and electricity they produce), (4) co-generation (combining the production of electricity and recoverable heat), (5) permutations of these together, and (6) permutations of these combined with more 'business-as-usual' approaches. The detailed assumptions and methods behind these models are described in Part I of this article pair.

The U.S. Strategic Petroleum Reserve stores crude oil in 62 solution-mined caverns in salt domes located in Texas and Louisiana. Historically, three-dimensional geomechanical simulations of the behavior of the caverns have been performed using a power law creep model. Using this method, and calibrating the creep coefficient to field data such as cavern closure and surface subsidence, has produced varying degrees of agreement with observed phenomena. However, as new salt dome locations are considered for oil storage facilities, pre-construction geomechanical analyses are required that need site-specific parameters developed from laboratory data obtained from core samples. The multi-mechanism deformation (M-D) model is a rigorous mathematical description of both transient and steady-state creep phenomena. Recent enhancements to the numerical integration algorithm within the model have created a more numerically stable implementation of the M-D model. This report presents computational analyses to compare the results of predictions of the geomechanical behavior at the West Hackberry SPR site using both models. The recently-published results using the power law creep model produced excellent agreement with an extensive set of field data. The M-D model results show similar agreement using parameters developed directly from laboratory data. It is also used to predict the behavior for the construction and operation of oil storage caverns at a new site, to identify potential problems before a final cavern layout is designed. Copyright 2010 ARMA, American Rock Mechanics Association.

Fatigue crack growth rates and rising displacement fracture thresholds have been measured for a 4130X steel in 45 MPa hydrogen gas. the ratio of minimum to maximum load (R-ratio) and cyclic frequency was varied to assess the effects of these variables on fatigue crack growth rates. Decreasing frequency and increasing R were both found to increase crack growth rate, however, these variables are not independent of each other. Changing frequency from 0.1 Hz to 1 Hz reduced crack growth rates at R = 0.5, but had no effect at R = 0.1. When applied to a design life calculation for a steel pressure vessel consistent with a typical hydrogen trailer tube, the measured fatigue and fracture data predicted a re-inspection interval of nearly 29 years, consistent with the excellent service history of such vessels which have been in use for many years. Copyright © 2010 by ASME.

Digital single-event transient (SET) measurements in a bulk 65-nm process are compared to transients measured in 130-nm and 90-nm processes. The measured SET widths are shorter in a 65-nm test circuit than SETs measured in similar 90-nm and 130-nm circuits, but, when the factors affecting the SET width measurements (in particular pulse broadening and the parasitic bipolar effect) are considered, the actual SET width trends are found to be more complex. The differences in the SET widths between test circuits can be attributed in part to differences in n-well contact area. These results help explain some of the inconsistencies in SET measurements presented by various researchers over the past few years. © 2010 IEEE.

We report on the design and measured results of a new SiGe HBT radiation hardening by design technique called the inverse-mode cascode (IMC). A third-generation SiGe HBT IMC device was tested in a time resolved ion beam induced charge collection (TRIBICC) system, and was found to have over a 75% reduction in peak current transients with the use of an n-Tiedown on the IMC sub-collector node. Digital shift registers in a 1st-generation SiGe HBT technology were designed and measured under a heavy-ion beam, and shown to increase the LET threshold over standard npn only shift registers. Using the CREME96 tool, the expected orbital bit-errors/day were simulated to be approximately 70% lower with the IMC shift register. These measured results help demonstrate the efficacy of using the IMC device as a low-cost means for improving the SEE radiation hardness of SiGe HBT technology without increasing area or power. © 2010 IEEE.

Heavy-ion microbeam and broadbeam data are presented for a 65 nm bulk CMOS process showing the existence of pulse quenching at normal and angular incidence for designs where the pMOS transistors are in common n-wells or isolated in separate n-wells. Experimental data and simulations show that pulse quenching is more prevalent in the common n-well design than the separate n-well design, leading to significantly reduced SET pulsewidths and SET cross-section in the common n-well design. © 2010 IEEE.

Here we demonstrate the suitability of robust nucleic acid affinity reagents in an integrated point-of-care diagnostic platform for monitoring proteomic biomarkers indicative of astronaut health in spaceflight applications. A model thioaptamer[1] targeting nuclear factor-kappa B (NF-KB) is evaluated in an on-chip electrophoretic gel-shift assay for human serum. Key steps of i) mixing sample with the aptamer, ii) buffer exchange, and iii) preconcentration of sample were successfully integrated upstream of fluorescence-based detection. Challenges due to i) nonspecific interactions with serum, and ii) preconcentration at a nanoporous membrane are discussed and successfully resolved to yield a robust, rapid, and fully-integrated diagnostic system.

We present a method for counting white blood cells that is uniquely compatible with centrifugation based microfluidics. Blood is deposited on top of one or more layers of density media within a microfluidic disk. Spinning the disk causes the cell populations within whole blood to settle through the media, reaching an equilibrium based on the density of each cell type. Separation and fluorescence measurement of cell types stained with a DNA dye is demonstrated using this technique. The integrated signal from bands of fluorescent microspheres is shown to be proportional to their initial concentration in suspension.

The Explosive Destruction System (EDS) was developed by Sandia National Laboratories for the US Army Product Manager for Non-Stockpile Chemical Materiel (PMNSCM) to destroy recovered, explosively configured, chemical munitions. PMNSCM currently has five EDS units that have processed over 1,400 items. The system uses linear and conical shaped charges to open munitions and attack the burster followed by chemical treatment of the agent. The main component of the EDS is a stainless steel, cylindrical vessel, which contains the explosion and the subsequent chemical treatment. Extensive modeling and testing have been used to design and qualify the vessel for different applications and conditions. The high explosive (HE) pressure histories and subsequent vessel response (strain histories) are modeled using the analysis codes CTH and LS-DYNA, respectively. Using the model results, a load rating for the EDS is determined based on design guidance provided in the ASME Code, Sect. VIII, Div. 3, Code Case No. 2564. One of the goals is to assess and understand the vessel's capacity in containing a wide variety of detonation sequences at various load levels. Of particular interest are to know the total number of detonation events at the rated load that can be processed inside each vessel, and a maximum load (such as that arising from an upset condition) that can be contained without causing catastrophic failure of the vessel. This paper will discuss application of Code Case 2564 to the stainless steel EDS vessels, including a fatigue analysis using a J-R curve, vessel response to extreme upset loads, and the effects of strain hardening from successive events. Copyright © 2010 by ASME.

We present a platform that combines patterned photopolymerized polymer monoliths with living radical polymerization (LRP) to develop a low cost microfluidic based immunoassay capable of sensitive (low to sub pM) and rapid (<30 minute) detection of protein in 100 μL sample. The introduction of LRP functionality to the porous monolith allows one step grafting of functionalized affinity probes from the monolith surface while the composition of the hydrophilic graft chain reduces non-specific interactions and helps to significantly improve the limit of detection.

In this paper HPC architectural characteristics and their impact on application performance and scaling are investigated. Performance data gathered over several generations of very large HPC systems like: ASC Red Storm, ASC Purple, and a large InfiniBand cluster - Red Sky, are analyzed. As the number of cache coherent cores and number of NUMA domains at a compute node keeps increasing, we analyze their impact with a few simple benchmarks and several applications. We present bottlenecks and remedies examining production applications. We conclude with preliminary early-hardware performance data from the ASC Cielo, a petaFLOPS class future capability system. © 2010 American Institute of Physics.

We have designed, fabricated, and characterized a digital microfluidic (DMF) platform to function as a central hub for interfacing multiple lab-on-a-chip sample processing modules towards automating the preparation of clinically-derived DNA samples for ultrahigh throughput sequencing (UHTS). The platform enables plug-and-play installation of a two-plate DMF device with consistent spacing, offers flexible connectivity for transferring samples between modules, and uses an intuitive programmable interface to control droplet/electrode actuations. Additionally, the hub platform uses transparent indium-tin oxide (ITO) electrodes to allow complete top and bottom optical access to the droplets on the DMF array, providing additional flexibility for various detection schemes.

We demonstrate mid-infrared electroluminescence from intersublevel transitions in self-assembled InAs quantum dots coupled to surface plasmon modes on metal hole arrays. Subwavelength metal hole arrays with different periodicity are patterned into the top contact of the broadband (9 - 15 μm) quantum dot material and the measured electroluminescence is compared to devices without a metal hole array. The resulting normally directed emission is narrowed and a splitting in the spectral structure is observed. By applying a coupled quantum electrodynamic model and using reasonable values for quantum dot distributions and plasmon linewidths we are able to reproduce the experimentally measured spectral characteristics of device emission when using strong coupling parameters. © 2010 SPIE.

Decision Trees, algorithms, software code, risk management, reports, plans, drawings, change control, presentations, and analysis- all useful tools and efforts but time consuming, resource intensive, and potentially costly for projects that have absolute schedule and budget constraints. What are necessary and prudent efforts when a customer calls with a major security problem that needs to be fixed with a proven, off-the-approval-list, multi-layered integrated system with high visibility and limited funding and expires at the end of the Fiscal Year? Whether driven by budget cycles, safety, or by management decree, many such projects begin with generic scopes and funding allocated based on a rapid management "guestimate." Then a Project Manager (PM) is assigned a project with a predefined and potentially limited scope, compressed schedule, and potentially insufficient funding. The PM is tasked to rapidly and cost effectively coordinate a requirements-based design, implementation, test, and turnover of a fully operational system to the customer, all while the customer is operating and maintaining an existing security system. Many project management manuals call this an impossible project that should not be attempted. However, security is serious business and the reality is that rapid deployment of proven systems via an "Extreme Project" is sometimes necessary. Extreme Projects can be wildly successful but require a dedicated team of security professionals lead by an experienced project manager using a highly-tailored and agile project management process with management support at all levels, all combined with significant interface with the customer. This paper does not advocate such projects or condone eliminating the valuable analysis and project management techniques. Indeed, having worked on a well-planned project provides the basis for experienced team members to complete Extreme Projects. This paper does, however, provide insight into what it takes for projects to be successfully implemented and accepted when completed under extreme conditions. ©2010 IEEE.

As security systems integrate more Information Technology the design of these systems has tended to become more complex. Some of the most difficult issues in designing Complex Security Systems (CSS) are: • Capturing Requirements • Defining Hardware Interfaces • Defining Software Interfaces • Integrating Technologies • Radio Systems • Voice Over IP Systems • Situational Awareness Systems. ©2010 IEEE.

The complexity of physical protection systems has increased to address modern threats to national security and emerging commercial technologies. A key element of modern physical protection systems is the data presented to the human operator used for rapid determination of the cause of an alarm, whether false (e.g., caused by an animal, debris, etc.) or real (e.g., a human adversary). Alarm assessment (the human validation of a sensor alarm) primarily relies on imaging technologies and video systems. Developing measures of effectiveness (MOE) that drive the design or evaluation of a video system or technology becomes a challenge, given the subjectivity of the application (e.g., alarm assessment). Sandia National Laboratories has conducted empirical analysis using field test data and mathematical models such as binomial distribution and Johnson target transfer functions to develop MOEs for video system technologies. Depending on the technology, the task of the security operator and the distance to the target, the Probability of Assessment (PAs) can be determined as a function of a variety of conditions or assumptions. PAs used as an MOE allows the systems engineer to conduct trade studies, make informed design decisions, or evaluate new higher-risk technologies. This paper outlines general video system design trade-offs, discusses ways video can be used to increase system performance, and lists MOEs for video systems used in subjective applications such as alarm assessment. ©2010 IEEE.

In this paper HPC architectural characteristics and their impact on application performance and scaling are investigated. Performance data gathered over several generations of very large HPC systems like: ASC Red Storm, ASC Purple, and a large InfiniBand cluster - Red Sky, are analyzed. As the number of cache coherent cores and number of NUMA domains at a compute node keeps increasing, we analyze their impact with a few simple benchmarks and several applications. We present bottlenecks and remedies examining production applications. We conclude with preliminary early-hardware performance data from the ASC Cielo, a petaFLOPS class future capability system. © 2010 American Institute of Physics.

Many possible applications requiring or benefiting from a wireless network are available for bolstering physical security and awareness at high security installations or facilities. These enhancements are not always straightforward and may require careful analysis, selection, tuning, and implementation of wireless technologies. In this paper, an introduction to wireless networks and the task of enhancing physical security is first given. Next, numerous applications of a wireless network are brought forth. The technical issues that arise when using a wireless network to support these applications are then discussed. Finally, a summary is presented. ©2010 IEEE.

Motivated by social network data mining problems such as link prediction and collaborative filtering, significant research effort has been devoted to computing topological measures including the Katz score and the commute time. Existing approaches typically approximate all pairwise relationships simultaneously. In this paper, we are interested in computing: the score for a single pair of nodes, and the top-k nodes with the best scores from a given source node. For the pairwise problem, we apply an iterative algorithm that computes upper and lower bounds for the measures we seek. This algorithm exploits a relationship between the Lanczos process and a quadrature rule. For the top-k problem, we propose an algorithm that only accesses a small portion of the graph and is related to techniques used in personalized PageRank computing. To test the scalability and accuracy of our algorithms we experiment with three real-world networks and find that these algorithms run in milliseconds to seconds without any preprocessing. © 2010 Springer-Verlag.

In a world plagued with improvised explosive devices, drugs and dangerous people, the desire to field technology to protect our police and military is providing a fertile market for the proliferation of protection technologies that range from the unproven to the disproven. The market place is currently being flooded with detection equipment making inflated and inaccurate marketing claims of high reliably, high detection probabilities, and ease of operation - all while offering detection capabilities at safe distances. The manufacturers of these devices have found a willing global marketplace, which includes some of the most dangerous places in the world. Despite a wealth of contradictory performance and testing data available on the Internet, sales of these devices remain brisk and profitable. Rather than enhancing the security of police and military personnel, the reliance on these unproven and disproven devices is creating a sense of false security that is actually lowering the safety of front-line forces in places like Iraq and Afghanistan. This paper addresses the development and distribution history of some of these devices and describes the testing performed by Sandia National Laboratories in Albuquerque, and other reputable testing agencies that illustrate the real danger in using this kind of unproven technology. ©2010 IEEE.

Variance estimates that are used in the analysis of radiation measurements must represent all of the measurement and computational uncertainties in order to obtain accurate parameter and uncertainty estimates. This report describes an approach for estimating components of the variance associated with both statistical and computational uncertainties. A multi-sensor fusion method is presented that renders parameter estimates for one-dimensional source models based on input from different types of sensors. Data obtained with multiple types of sensors improve the accuracy of the parameter estimates, and inconsistencies in measurements are also reflected in the uncertainties for the estimated parameter. Specific analysis examples are presented that incorporate a single gross neutron measurement with gamma-ray spectra that contain thousands of channels. The parameter estimation approach is tolerant of computational errors associated with detector response functions and source model approximations. © 2010 IEEE.

In this paper, a numerical model incorporating micro-porous layers (MPLs) is presented for simulating water transport within the gas diffusion layers (GDLs) and MPLs as well as across their interfaces in a polymer electrolyte membrane (PEM) fuel cell. One-dimensional analysis is conducted to investigate the impacts of MPL and GDL properties on the liquid-water profile across the anode GDL-MPL and cathode MPL-GDL regions. Furthermore, two-dimensional numerical simulations that take MPLs into account are also carried out to elucidate liquid water transport, particularly through-plane liquid-water profile in a PEM fuel cell. Results from case studies are presented. ©The Electrochemical Society.

We report on advancements of our microscale isoelectric fractionation (μIEFr) methodology for fast on-chip separation and concentration of proteins based on their isoelectric points (pI). We establish that proteins can be fractionated depending on posttranslational modifications into different pH specific bins, from where they can be efficiently transferred to downstream membranes for additional processing and analysis. This technology can enable on-chip multidimensional glycoproteomics analysis, as a new approach to expedite biomarker identification and verification.

We present a shape-first approach to finding automobiles and trucks in overhead images and include results from our analysis of an image from the Overhead Imaging Research Dataset [1]. For the OIRDS, our shape-first approach traces candidate vehicle outlines by exploiting knowledge about an overhead image of a vehicle: a vehicle's outline fits into a rectangle, this rectangle is sized to allow vehicles to use local roads, and rectangles from two different vehicles are disjoint. Our shape-first approach can efficiently process high-resolution overhead imaging over wide areas to provide tips and cues for human analysts, or for subsequent automatic processing using machine learning or other analysis based on color, tone, pattern, texture, size, and/or location (shape first). In fact, computationally-intensive complex structural, syntactic, and statistical analysis may be possible when a shape-first work flow sends a list of specific tips and cues down a processing pipeline rather than sending the whole of wide area imaging information. This data flow may fit well when bandwidth is limited between computers delivering ad hoc image exploitation and an imaging sensor. As expected, our early computational experiments find that the shape-first processing stage appears to reliably detect rectangular shapes from vehicles. More intriguing is that our computational experiments with six-inch GSD OIRDS benchmark images show that the shape-first stage can be efficient, and that candidate vehicle locations corresponding to features that do not include vehicles are unlikely to trigger tips and cues. We found that stopping with just the shape-first list of candidate vehicle locations, and then solving a weighted, maximal independent vertex set problem to resolve conflicts among candidate vehicle locations, often correctly traces the vehicles in an OIRDS scene. © 2010 IEEE.

Sandia's Large Optics Coating Operation has extensive results of laser induced damage threshold (LIDT) testing of its anti-reflection (AR) and high reflection coatings on substrates pitch polished using ceria and washed in a process that includes an alumina wash step. The purpose of the alumina wash step is to remove residual polishing compound to minimize its role in laser damage. These LIDT tests are for multi longitudinal mode, ns class pulses at 1064 nm and 532 nm (NIF-MEL protocol) and mode locked, sub-ps class pulses at 1054 nm (Sandia measurements), and show reasonably high and adequate laser damage resistance for coatings in the beam trains of Sandia's Z-Backlighter terawatt and petawatt lasers. An AR coating in addition to coatings of our previous reports confirms this with LIDTs of 33.0 J/cm2 for 3.5 ns pulses and 1.8 J/cm2 for 350 fs pulses. In this paper, we investigate both ceria and zirconia in doublesided polishing (common for large flat Z-Backlighter laser optics) as they affect LIDTs of an AR coating on fused silica substrates washed with or without the alumina wash step. For these AR coated, double-sided polished surfaces, ceria polishing in general affords better resistance to laser damage than zirconia polishing and laser damage is less likely with the alumina wash step than without it. This is supported by specific results of laser damage tests with 3.5 ns, multi longitudinal mode, single shot pulses at 1064 nm and 532 nm, with 7.0 ns, single and multi longitudinal mode, single and multi shot pulses at 532 nm, and with 350 fs, mode-locked, single shot pulses at 1054 nm. © 2010 Copyright SPIE - The International Society for Optical Engineering.

This paper presents an integrated microfluidic system for selectively interrogating parallel biosensors at programmed time intervals. Specifically, the microfluidic system is used for delivering a volume of sample from a single source to a surface-based arrayed biosensor. In this case the biosensors were an array of electrochemical electrodes modified with sample specific capture probes. In addition, the sample was required to be captured, stored and removed for additional laboratory analysis. This was accomplished by a plastic laminate stack in which each thin laminate was patterned by CO2 laser ablation to form microchannels and two novel valves. The first valve was a normally closed type opened by heat via an electrically resistive wire. The second valve was a check type integrated into a removable storage chamber. This setup allows for remote and leave-behind sensing applications and also containment of sensed sample for further laboratory analysis. ©2010 IEEE.

An anisotropy in a scintillator's response to neutron elastic scattering interactions can in principle be used to gather directional information about a neutron source using interactions in a single detector. In crystalline organic scintillators, such as anthracene, both the amplitude and the time structure of the scintillation light pulse vary with the direction of the proton recoil with respect to the crystalline axes. Therefore, we have investigated the exploitation of this effect to enable compact, high-efficiency fast neutron detectors that have directional sensitivity via a precise measurement of the pulse shape. We report measurements of the pulse height and shape dependence on proton recoil angle in anthracene, stilbene, p-terphenyl, diphenyl anthracene (DPA), and tetraphenyl butadiene (TPB). Image reconstruction for simulated neutron sources is demonstrated using maximum likelihood methods for optimal directional sensitivity. © 2010 IEEE.

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The swing equations for renewable generators connected to the grid are developed and a wind turbine is used as an example. The swing equations for the renewable generators are formulated as a natural Hamiltonian system with externally applied non-conservative forces. A two-step process referred to as Hamiltonian Surface Shaping and Power Flow Control (HSSPFC) is used to analyze and design feedback controllers for the renewable generators system. This formulation extends previous results on the analytical verification of the Potential Energy Boundary Surface (PEBS) method to nonlinear control analysis and design and justifies the decomposition of the system into conservative and non-conservative systems to enable a two-step, serial analysis and design procedure. The first step is to analyze the system as a conservative natural Hamiltonian system with no externally applied non-conservative forces. The Hamiltonian surface of the swing equations is related to the Equal-Area Criterion and the PEBS method to formulate the nonlinear transient stability problem. This formulation demonstrates the effectiveness of proportional feedback control to expand the stability region. The second step is to analyze the system as natural Hamiltonian system with externally applied non-conservative forces. The time derivative of the Hamiltonian produces the work/rate (power flow) equations which is used to ensure balanced power flows from the renewable generators to the loads. The Second Law of Thermodynamics is applied to the power flow equations to determine the stability boundaries (limit cycles) of the renewable generators system and enable design of feedback controllers that meet stability requirements while maximizing the power generation and flow to the load. Necessary and sufficient conditions for stability of renewable generators systems are determined based on the concepts of Hamiltonian systems, power flow, exergy (the maximum work that can be extracted from an energy flow) rate, and entropy rate. © 2010 IEEE.

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An anisotropy in a scintillator's response to neutron elastic scattering interactions can in principle be used to gather directional information about a neutron source using interactions in a single detector. In crystalline organic scintillators, such as anthracene, both the amplitude and the time structure of the scintillation light pulse vary with the direction of the proton recoil with respect to the crystalline axes. Therefore, we have investigated the exploitation of this effect to enable compact, high-efficiency fast neutron detectors that have directional sensitivity via a precise measurement of the pulse shape. We report measurements of the pulse height and shape dependence on proton recoil angle in anthracene, stilbene, p-terphenyl, diphenyl anthracene (DPA), and tetraphenyl butadiene (TPB). Image reconstruction for simulated neutron sources is demonstrated using maximum likelihood methods for optimal directional sensitivity. © 2010 IEEE.

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We report on a scalable electrostatic process to transfer epitaxial graphene to arbitrary glass substrates, including Pyrex and Zerodur. This transfer process could enable wafer-level integration of graphene with structured and electronically-active substrates such as MEMS and CMOS. We will describe the electrostatic transfer method and will compare the properties of the transferred graphene with nominally-equivalent 'as-grown' epitaxial graphene on SiC. The electronic properties of the graphene will be measured using magnetoresistive, four-probe, and graphene field effect transistor geometries [1]. To begin, high-quality epitaxial graphene (mobility 14,000 cm2/Vs and domains >100 {micro}m2) is grown on SiC in an argon-mediated environment [2,3]. The electrostatic transfer then takes place through the application of a large electric field between the donor graphene sample (anode) and the heated acceptor glass substrate (cathode). Using this electrostatic technique, both patterned few-layer graphene from SiC(000-1) and chip-scale monolayer graphene from SiC(0001) are transferred to Pyrex and Zerodur substrates. Subsequent examination of the transferred graphene by Raman spectroscopy confirms that the graphene can be transferred without inducing defects. Furthermore, the strain inherent in epitaxial graphene on SiC(0001) is found to be partially relaxed after the transfer to the glass substrates.

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We report on the novel room temperature method of synthesizing advanced nuclear fuels; a method that virtually eliminates any volatility of components. This process uses radiolysis to form stable nanoparticle (NP) nuclear transuranic (TRU) fuel surrogates and in-situ heated stage TEM to sinter the NPs. The radiolysis is performed at Sandia's Gamma Irradiation Facility (GIF) 60Co source (3 x 10{sup 6} rad/hr). Using this method, sufficient quantities of fuels for research purposes can be produced for accelerated advanced nuclear fuel development. We are focused on both metallic and oxide alloy nanoparticles of varying compositions, in particular d-U, d-U/La alloys and d-UO2 NPs. We present detailed descriptions of the synthesis procedures, the characterization of the NPs, the sintering of the NPs, and their stability with temperature. We have employed UV-vis, HRTEM, HAADF-STEM imaging, single particle EDX and EFTEM mapping characterization techniques to confirm the composition and alloying of these NPs.

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This presentation on wind energy discusses: (1) current industry status; (2) turbine technologies; (3) assessment and siting; and (4) grid integration. There are no fundamental technical barriers to the integration of 20% wind energy into the nation's electrical system, but there needs to be a continuing evolution of transmission planning and system operation policy and market development for this to be most economically achieved.

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Magnetic Liner Inertial Fusion (MagLIF) [S. A. Slutz, et al., Phys. Plasmas 17 056303 (2010)] is a promising new concept for achieving >100 kJ of fusion yield on Z. The greatest threat to this concept is the Magneto-Rayleigh-Taylor (MRT) instability. Thus an experimental campaign has been initiated to study MRT growth in fast-imploding (<100 ns) cylindrical liners. The first sets of experiments studied aluminum liner implosions with prescribed sinusoidal perturbations (see talk by D. Sinars). By contrast, this poster presents results from the latest sets of experiments that used unperturbed beryllium (Be) liners. The purpose for using Be is that we are able to radiograph 'through' the liner using the 6-keV photons produced by the Z-Beamlet backlighting system. This has enabled us to obtain time-resolved measurements of the imploding liner's density as a function of both axial and radial location throughout the field of view. This data is allowing us to evaluate the integrity of the inside (fuel-confining) surface of the imploding liner as it approaches stagnation.

We present the preliminary design of a Z experiment intended to observe the growth of several hydrodynamic instabilities (RT, RM, and KH) in a high-energy-density plasma. These experiments rely on the Z-machine's unique ability to launch cm-sized slabs of cold material (known as flyer plates) to velocities of several times 10 km/s. During the proposed experiment, the flyer plate will impact a cm-sized target with an embedded interface that has a prescribed sinusoidal perturbation. The flyer plate will generate a strong shock that propagates into the target and later initiates unstable growth of the perturbation. The goal of the experiment is to observe the perturbation at various stages of its evolution as it transitions from linear to non-linear growth, and finally to a fully turbulent state.

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Laser-accelerated proton beams can be used in a variety of applications, e.g. ultrafast radiography of dense objects or strong electromagnetic fields. Therefore high energies of tens of MeV are required. We report on proton-acceleration experiments with a 150 TW laser system using mm-sized thin foils and mass-reduced targets of various thicknesses. Thin- foil targets yielded maximum energies of 50 MeV. A further reduction of the target dimensions from mm-size to 250 x 250 x 25 microns increased the maximum proton energy to >65 MeV, which is comparable to proton energies measured only at higher-energy, Petawatt-class laser systems. The dependence of the maximum energy on target dimensions was investigated, and differences between mm-sized thin foils and mass-reduced targets will be reported.

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The objectives of this presentation are: (1) To determine if healthcare settings serve as intensive transmission environments for influenza epidemics, increasing effects on communities; (2) To determine which mitigation strategies are best for use in healthcare settings and in communities to limit influenza epidemic effects; and (3) To determine which mitigation strategies are best to prevent illness in healthcare workers.

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Cigarette smoking presented the most significant public health challenge in the United States in the 20th Century and remains the single most preventable cause of morbidity and mortality in this country. A number of System Dynamics models exist that inform tobacco control policies. We reviewed them and discuss their contributions. We developed a theory of the societal lifecycle of smoking, using a parsimonious set of feedback loops to capture historical trends and explore future scenarios. Previous work did not explain the long-term historical patterns of smoking behaviors. Much of it used stock-and-flow to represent the decline in prevalence in the recent past. With noted exceptions, information feedbacks were not embedded in these models. We present and discuss our feedback-rich conceptual model and illustrate the results of a series of simulations. A formal analysis shows phenomena composed of different phases of behavior with specific dominant feedbacks associated with each phase. We discuss the implications of our society's current phase, and conclude with simulations of what-if scenarios. Because System Dynamics models must contain information feedback to be able to anticipate tipping points and to help identify policies that exploit leverage in a complex system, we expanded this body of work to provide an endogenous representation of the century-long societal lifecycle of smoking.

Negative bias temperature instability is an issue of critical importance as the space electronics industry evolves because it may dominate the reliability lifetime. Understanding its physical origin is therefore essential in determining how best to search for methods of mitigation. It has been suggested that the magnitude of the effect is strongly dependent on circuit operation conditions (static or dynamic modes). In the present work, we examine the time constants related to the charging and recovery of trapped charged induced by NBTI in HfSiON gate dielectric devices. In previous work, we avoided the issue of charge relaxation during acquisition of the I{sub ds}(V{sub gs}) curve by invoking a continuous stressing technique whereby {Delta}V{sub th} was extracted from a series of single point I{sub ds} measurements. This method relied heavily on determination of the initial value of the source-drain current (I{sub ds}{sup o}) prior to application of gate-source stress. In the present work we have used a new pulsed measurement system (Keithley SCS 4200-PIV) which not only removes this uncertainty but also permits dynamic measurements in which devices are AC stressed (Fig. 1a) or subjected to cycles of continued DC stresses followed by relaxation (Fig. 1b). We can now examine the charging and recovery characteristics of NBTI with higher precision than previously possible. We have performed NBTI stress experiments at room temperature on p-channel MOSFETs made with HfSiON gate dielectrics. In all cases the devices were stressed in the linear regime with V{sub ds}=-0.1V. We have defined two separate waveforms/pulse trains as illustrated in Fig 1. These were applied to the gate of the MOSFET. Firstly we examined the charging characteristics by applying an AC stress at 2.5MHz or 10Hz for different times. For a 50% duty cycle this corresponded to V{sub gs} = - 2V pulses for 200ns or 500ms followed by V{sub gs} = 0V pulses for 200ns or 500ms recovery respectively. In between 'bursts' of AC stress cycles, the I{sub ds}(V{sub gs}) characteristic in the range (-0.6V, -1.3V) was measured in 10.2 {micro}s. V{sub th} was extracted directly from this curve, or from a single I{sub ds} point normalized to the initial I{sub ds}{sup o} using our previous method. The resulting I{sub ds}/I{sub ds}{sup o} curves are compared; in Fig 2, the continuous stress results are included. In the second method, we examined the recovery dynamic by holding V{sub gs} = 0V for a finite amount of time (range 100 ns to 100 ms) following stress at V{sub gs} = - 2V for various times. In Fig 3 we compare |{Delta}V{sub th}(t)| results for recovery times of 100ms, 1ms, 100{micro}s, 50{micro}s, 25{micro}s, 10{micro}s, 100ns, and DC (i.e. no recovery) The data in Fig 2 shows that with a high frequency stress (2.5MHz) devices undergo significantly less (but finite) current degradation than devices stressed at 10Hz. This appears to be limited by charging and not by recovery. Fig 3 supports this hypothesis since for 100ns recovery periods, only a small percentage of the trapped charge relaxes. Detailed explanation of these experiments will be presented at the conference.

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Loki-Infect 3 is a desktop application intended for use by community-level decision makers. It allows rapid construction of small-scale studies of emerging or hypothetical infectious diseases in their communities and evaluation of the potential effectiveness of various containment strategies. It was designed with an emphasis on modularity, portability, and ease of use. Our goal is to make this program freely available to community workers across the world.

Injection of CO2 into formations containing brine is proposed as a long-term sequestration solution. A significant obstacle to sequestration performance is the presence of existing wells providing a transport pathway out of the sequestration formation. To understand how heterogeneity impacts the leakage rate, we employ two dimensional models of the CO2 injection process into a sandstone aquifer with shale inclusions to examine the parameters controlling release through an existing well. This scenario is modeled as a constant-rate injection of super-critical CO2 into the existing formation where buoyancy effects, relative permeabilities, and capillary pressures are employed. Three geologic controls are considered: stratigraphic dip angle, shale inclusion size and shale fraction. In this study, we examine the impact of heterogeneity on the amount and timing of CO2 released through a leaky well. Sensitivity analysis is performed to classify how various geologic controls influence CO2 loss. A 'Design of Experiments' approach is used to identify the most important parameters and combinations of parameters to control CO2 migration while making efficient use of a limited number of computations. Results are used to construct a low-dimensional description of the transport scenario. The goal of this exploration is to develop a small set of parametric descriptors that can be generalized to similar scenarios. Results of this work will allow for estimation of the amount of CO2 that will be lost for a given scenario prior to commencing injection. Additionally, two-dimensional and three-dimensional simulations are compared to quantify the influence that surrounding geologic media has on the CO2 leakage rate.

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