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Generic small modular reactor plant design

Cipiti, Benjamin B.; Jordan, Sabina E.; Baum, Gregory; Lewis, Tom G.

This report gives an overview of expected design characteristics, concepts, and procedures for small modular reactors. The purpose of this report is to provide those who are interested in reducing the cost and improving the safety of advanced nuclear power plants with a generic design that possesses enough detail in a non-sensitive manner to give merit to their conclusions. The report is focused on light water reactor technology, but does add details on what could be different in a more advanced design (see Appendix). Numerous reactor and facility concepts were used for inspiration (documented in the bibliography). The final design described here is conceptual and does not reflect any proposed concept or sub-systems, thus any details given here are only relevant within this report. This report does not include any design or engineering calculations.

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Renewable Source Controls for Grid Stability

Neely, Jason C.; Elliott, Ryan T.; Silva-Monroy, Cesar A.; Schoenwald, David A.

The goal of this study was to evaluate the small signal and transient stability of the Western Electricity Coordinating Council (WECC) under high penetrations of renewable energy, and to identify control technologies that would improve the system performance. The WECC is the regional entity responsible for coordinating and promoting bulk electric system reliability in the Western Interconnection. Transient stability is the ability of the power system to maintain synchronism after a large disturbance while small signal stability is the ability of the power system to maintain synchronism after a small disturbance. Transient stability analysis usually focuses on the relative rotor angle between synchronous machines compared to some stability margin. For this study we employed generator speed relative to system speed as a metric for assessing transient stability. In addition, we evaluated the system transient response using the system frequency nadir, which provides an assessment of the adequacy of the primary frequency control reserves. Small signal stability analysis typically identifies the eigenvalues or modes of the system in response to a disturbance. For this study we developed mode shape maps for the different scenarios. Prony analysis was applied to generator speed after a 1.4 GW, 0.5 second, brake insertion at various locations. Six different WECC base cases were analyzed, including the 2022 light spring case which meets the renewable portfolio standards. Because of the difficulty in identifying the cause and effect relationship in large power system models with different scenarios, several simulations were run on a 7-bus, 5-generator system to isolate the effects of different configurations. Based on the results of the study, for a large power system like the WECC, incorporating frequency droop into wind/solar systems provides a larger benefit to system transient response than replacing the lost inertia with synthetic inertia. From a small signal stability perspective, the increase in renewable penetration results in subtle changes to the system modes. In general, mode frequencies increase slightly, and mode shapes remain similar. The system frequency nadir for the 2022 light spring case was slightly lower than the other cases, largely because of the reduced system inertia. However, the nadir is still well above the minimum load shedding frequency of 59.5 Hz. Finally, several discrepancies were identified between actual and reported wind penetration, and additional work on wind/solar modeling is required to increase the fidelity of the WECC models.

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A Comparative Critical Analysis of Modern Task-Parallel Runtimes

Wheeler, Kyle B.; Stark, Dylan T.

The rise in node-level parallelism has increased interest in task-based parallel runtimes for a wide array of application areas. Applications have a wide variety of task spawning patterns which frequently change during the course of application execution, based on the algorithm or solver kernel in use. Task scheduling and load balance regimes, however, are often highly optimized for specific patterns. This paper uses four basic task spawning patterns to quantify the impact of specific scheduling policy decisions on execution time. We compare the behavior of six publicly available tasking runtimes: Intel Cilk, Intel Threading Building Blocks (TBB), Intel OpenMP, GCC OpenMP, Qthreads, and High Performance ParalleX (HPX). With the exception of Qthreads, the runtimes prove to have schedulers that are highly sensitive to application structure. No runtime is able to provide the best performance in all cases, and those that do provide the best performance in some cases, unfortunately, provide extremely poor performance when application structure does not match the scheduler's assumptions.

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Enhanced Micellar Catalysis LDRD

Betty, Rita G.; Glen, Crystal C.; Alam, Todd M.; Taggart, Gretchen S.; Tucker, Mark D.; Rivera, Danielle; Kinnan, Mark

The primary goals of the Enhanced Micellar Catalysis project were to gain an understanding of the micellar environment of DF-200, or similar liquid CBW surfactant-based decontaminants, as well as characterize the aerosolized DF-200 droplet distribution and droplet chemistry under baseline ITW rotary atomization conditions. Micellar characterization of limited surfactant solutions was performed externally through the collection and measurement of Small Angle X-Ray Scattering (SAXS) images and Cryo-Transmission Electron Microscopy (cryo-TEM) images. Micellar characterization was performed externally at the University of Minnesotas Characterization Facility Center, and at the Argonne National Laboratory Advanced Photon Source facility. A micellar diffusion study was conducted internally at Sandia to measure diffusion constants of surfactants over a concentration range, to estimate the effective micelle diameter, to determine the impact of individual components to the micellar environment in solution, and the impact of combined components to surfactant phase behavior. Aerosolized DF-200 sprays were characterized for particle size and distribution and limited chemical composition. Evaporation rates of aerosolized DF-200 sprays were estimated under a set of baseline ITW nozzle test system parameters.

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Simulating neural systems with Xyce

Schiek, Richard; Thornquist, Heidi K.; Warrender, Christina E.; Mei, Ting; Teeter, Corinne M.; Aimone, James B.

Sandias parallel circuit simulator, Xyce, can address large scale neuron simulations in a new way extending the range within which one can perform high-fidelity, multi-compartment neuron simulations. This report documents the implementation of neuron devices in Xyce, their use in simulation and analysis of neuron systems.

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Methodology to Determine the Technical Performance and Value Proposition for Grid-Scale Energy Storage Systems: A Study for the DOE Energy Storage Systems Program

Byrne, Raymond H.

As the amount of renewable generation increases, the inherent variability of wind and photovoltaic systems must be addressed in order to ensure the continued safe and reliable operation of the nation’s electricity grid. Grid-scale energy storage systems are uniquely suited to address the variability of renewable generation and to provide other valuable grid services. The goal of this report is to quantify the technical performance required to provide different grid benefits and to specify the proper techniques for estimating the value of grid-scale energy storage systems.

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Forming Rotated SAR Images by Real-Time Motion Compensation

Doerry, Armin W.

Proper waveform parameter selection allows collecting Synthetic Aperture Radar (SAR) phase history data on a rotated grid in the Fourier Space of the scene being imaged. Subsequent image formation preserves the rotated geometry to allow SAR images to be formed at arbitrary rotation angles without the use of computationally expensive interpolation or resampling operations. This should be useful where control of image orientation is desired such as generating squinted stripmaps and VideoSAR applications, among others.

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Transmitter Passband Requirements for Imaging Radar

Doerry, Armin W.

In high-power microwave power amplifiers for radar, distortion in both amplitude and phase should generally be expected. Phase distortions can be readily equalized. Some amplitude distortions are more problematic than others. In general, especially for SAR using LFM chirps, low frequency modulations such as gain slopes can be tolerated much better than multiple cycles of ripple across the passband of the waveform.

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Discriminative feature-rich models for syntax-based machine translation

Dixon, Kevin R.

This report describes the campus executive LDRD %E2%80%9CDiscriminative Feature-Rich Models for Syntax-Based Machine Translation,%E2%80%9D which was an effort to foster a better relationship between Sandia and Carnegie Mellon University (CMU). The primary purpose of the LDRD was to fund the research of a promising graduate student at CMU; in this case, Kevin Gimpel was selected from the pool of candidates. This report gives a brief overview of Kevin Gimpel's research.

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Use of radial self-field geometry for intense pulsed ion beam generation above 6 MeV on Hermes III

Harper-Slaboszewicz, V.

We investigate the generation and propagation of intense pulsed ion beams at the 6 MeV level and above using the Hermes III facility at Sandia National Laboratories. While high-power ion beams have previously been produced using Hermes III, we have conducted systematic studies of several ion diode geometries for the purpose of maximizing focused ion energy for a number of applications. A self-field axial-gap diode of the pinch reflex type and operated in positive polarity yielded beam power below predicted levels. This is ascribed both to power flow losses of unknown origin upstream of the diode load in Hermes positive polarity operation, and to anomalies in beam focusing in this configuration. A change to a radial self-field geometry and negative polarity operation resulted in greatly increased beam voltage (> 6 MeV) and estimated ion current. A comprehensive diagnostic set was developed to characterize beam performance, including both time-dependent and time-integrated measurements of local and total beam power. A substantial high-energy ion population was identified propagating in reverse direction, i.e. from the back side of the anode in the electron beam dump. While significant progress was made in increasing beam power, further improvements in assessing the beam focusing envelope will be required before ultimate ion generation efficiency with this geometry can be completely determined.

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Computational optimization of synthetic water channels

Rempe, Susan; Rogers, David M.

Membranes for liquid and gas separations and ion transport are critical to water purification, osmotic energy generation, fuel cells, batteries, supercapacitors, and catalysis. Often these membranes lack pore uniformity and robustness under operating conditions, which can lead to a decrease in performance. The lack of uniformity means that many pores are non-functional. Traditional membranes overcome these limitations by using thick membrane materials that impede transport and selectivity, which results in decreased performance and increased operating costs. For example, limitations in membrane performance demand high applied pressures to deionize water using reverse osmosis. In contrast, cellular membranes combine high flux and selective transport using membrane-bound protein channels operating at small pressure differences. Pore size and chemistry in the cellular channels is defined uniformly and with sub-nanometer precision through protein folding. The thickness of these cellular membranes is limited to that of the cellular membrane bilayer, about 4 nm thick, which enhances transport. Pores in the cellular membranes are robust under operating conditions in the body. Recent efforts to mimic cellular water channels for efficient water deionization produced a significant advance in membrane function. The novel biomimetic design achieved a 10-fold increase in membrane permeability to water flow compared to commercial membranes and still maintained high salt rejection. Despite this success, there is a lack of understanding about why this membrane performs so well. To address this lack of knowledge, we used highperformance computing to interrogate the structural and chemical environments experienced by water and electrolytes in the newly created biomimetic membranes. We also compared the solvation environments between the biomimetic membrane and cellular water channels. These results will help inform future efforts to optimize and tune the performance of synthetic biomimetic membranes for applications in water purification, energy, and catalysis.

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Estimating the Maximum Potential Revenue for Grid Connected Electricity Storage: Arbitrage and Regulation

Byrne, Raymond H.

The valuation of an electricity storage device is based on the expected future cash flow generated by the device. Two potential sources of income for an electricity storage system are energy arbitrage and participation in the frequency regulation market. Energy arbitrage refers to purchasing (storing) energy when electricity prices are low, and selling (discharging) energy when electricity prices are high. Frequency regulation is an ancillary service geared towards maintaining system frequency, and is typically procured by the independent system operator in some type of market. This paper outlines the calculations required to estimate the maximum potential revenue from participating in these two activities. First, a mathematical model is presented for the state of charge as a function of the storage device parameters and the quantities of electricity purchased/sold as well as the quantities offered into the regulation market. Using this mathematical model, we present a linear programming optimization approach to calculating the maximum potential revenue from an electricity storage device. The calculation of the maximum potential revenue is critical in developing an upper bound on the value of storage, as a benchmark for evaluating potential trading strategies, and a tool for capital finance risk assessment. Then, we use historical California Independent System Operator (CAISO) data from 2010-2011 to evaluate the maximum potential revenue from the Tehachapi wind energy storage project, an American Recovery and Reinvestment Act of 2009 (ARRA) energy storage demonstration project. We investigate the maximum potential revenue from two different scenarios: arbitrage only and arbitrage combined with the regulation market. Our analysis shows that participation in the regulation market produces four times the revenue compared to arbitrage in the CAISO market using 2010 and 2011 data. Then we evaluate several trading strategies to illustrate how they compare to the maximum potential revenue benchmark. We conclude with a sensitivity analysis with respect to key parameters.

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Creep behavior of a Sn-Ag-Bi Pb-free solder

Materials

Vianco, Paul; Rejent, Jerome A.; Grazier, John M.; Kilgo, Alice C.

Compression creep tests were performed on the ternary 91.84Sn-3.33Ag-4.83Bi (wt.%, abbreviated Sn-Ag-Bi) Pb-free alloy. The test temperatures were: -25 °C, 25 °C, 75 °C, 125 °C, and 160 °C (± 0.5 °C). Four loads were used at the two lowest temperatures and five at the higher temperatures. The specimens were tested in the as-fabricated condition or after having been subjected to one of two air aging conditions: 24 hours at either 125 °C or 150 °C. The strain-time curves exhibited frequent occurrences of negative creep and small-scale fluctuations, particularly at the slower strain rates, that were indicative of dynamic recrystallization (DRX) activity. The source of tertiary creep behavior at faster strain rates was likely to also be DRX rather than a damage accumulation mechanism. Overall, the strain-time curves did not display a consistent trend that could be directly attributed to the aging condition. The sinh law equation satisfactorily represented the minimum strain rate as a function of stress and temperature so as to investigate the deformation rate kinetics: dε/dtmin = Asinhn (ασ) exp (-ΔH/RT). The values of α, n, and ΔH were in the following ranges (±95% confidence interval): α, 0.010-0.015 (±0.005 1/MPa); n, 2.2-3.1 (±0.5); and ΔH, 54-66 (±8 kJ/mol). The rate kinetics analysis indicated that short-circuit diffusion was a contributing mechanism to dislocation motion during creep. The rate kinetics analysis also determined that a minimum creep rate trend could not be developed between the as-fabricated versus aged conditions. This study showed that the elevated temperature aging treatments introduced multiple changes to the Sn-Ag-Bi microstructure that did not result in a simple loss ("softening") of its mechanical strength. © 2012 by Sandia Corporation.

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Quality Engineering as a Profession

Kolb, Rachel R.; Hoover, Marcey L.

Over the course of time, the profession of quality engineering has witnessed significant change, from its original emphasis on quality control and inspection to a more contemporary focus on upholding quality processes throughout the organization and its product realization activities. This paper describes the profession of quality engineering, exploring how today's quality engineers and quality professionals are certified individuals committed to upholding quality processes and principles while working with different dimensions of product development. It also discusses the future of the quality engineering profession and the future of the quality movement as a whole.

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Quality Engineering as a Discipline of Study

Kolb, Rachel R.; Hoover, Marcey L.

The current framework for quality scholarship in the United States ranges from the training and education of future quality engineers, managers, and professionals to focused and sustained research initiatives that, through academic institutions and other organizations, aim to improve the knowledge and application of quality across a variety of sectors. Numerous quality journals also provide a forum for professional dissemination of information.

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Final Report on Reliability and Lifetime Prediction

Gillen, Kenneth T.; Wise, Jonathan; Jones, Gary D.; Al Causa, G.; Terrill, Edward R.; Borowczak, Marc

This document highlights the important results obtained from the subtask of the Goodyear CRADA devoted to better understanding reliability of tires and to developing better lifetime prediction methods. The overall objective was to establish the chemical and physical basis for the degradation of tires using standard as well as unique models and experimental techniques. Of particular interest was the potential application of our unique modulus profiling apparatus for assessing tire properties and for following tire degradation. During the course of this complex investigation, extensive relevant information was generated, including experimental results, data analyses and development of models and instruments. Detailed descriptions of the findings are included in this report.

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Component-Based Scientific Application Development

Salinger, Andrew G.

Over the past few years, we have defined and gone a long ways towards implementing a component-based strategy for building scientific application codes. We have asserted that this approach offers significant advantages over a model of writing project-based application codes. There are now several technical and programmatic successes that validate these claims. Not only are there net benefits to code projects that follow this strategy, but also the most striking gains are for the long-term impact and productivity of our computational science organizations.

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Elpasolite scintillators

Doty, F.P.; Yang, Pin; Zhou, Xiaowang; Rodriguez, Mark A.

This work was funded by the U.S. Department of Energy Office of Nonproliferation Research to develop elpasolite materials, with an emphasis on high-atomic-number rare-earth elpasolites for gamma-ray spectrometer applications. Low-cost, high-performance gamma-ray spectrometers are needed for detection of nuclear proliferation. Cubic materials, such as some members of the elpasolite family (A2BLnX6; Ln-lanthanide and X-halogen), hold promise due to their high light output, proportionality, and potential for scale-up. Using both computational and experimental studies, a systematic investigation of the compositionstructureproperty relationships of these high-atomic-number elpasolite halides was performed. The results reduce the barrier to commercialization of large single crystals or transparent ceramics, and will facilitate economical scale-up of elpasolites for high-sensitivity gamma-ray spectroscopy.

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Thermally programmable pH buffers

ACS Applied Materials and Interfaces

Van Gough, Dara; Bunker, B.C.; Roberts, Mark E.; Huber, Dale L.; Zarick, Holly F.; Austin, Mariah J.; Wheeler, Jill S.; Moore, Diana; Spoerke, Erik D.

Many reactions in both chemistry and biology rely on the ability to precisely control and fix the solution concentrations of either protons or hydroxide ions. In this report, we describe the behavior of thermally programmable pH buffer systems based on the copolymerization of varying amounts of acrylic acid (AA) groups into N-isopropylacrylamide polymers. Because the copolymers undergo phase transitions upon heating and cooling, the local environment around the AA groups can be reversibly switched between hydrophobic and hydrophilic states affecting the ionization behavior of the acids. Results show that moderate temperature variations can be used to change the solution pH by two units. However, results also indicate that the nature of the transition and its impact on the pH values are highly dependent on the AA content and the degree of neutralization. © 2012 American Chemical Society.

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Spatiotemporal mapping of concentration polarization induced pH changes at nanoconstrictions

ACS Nano

Mai, Junyu; Miller, Hanna; Hatch, Anson

Under an applied electric field, concentration polarization (CP) arises from ion permselectivity of most nanoporous materials and biological ion channels. We present novel methods to quantitatively assess CP-induced spatiotemporal changes of pH that may significantly impact transport dynamics, device functionality, and physicochemical properties of molecular analytes in devices with nanofluidic constrictions. We measured pH fluctuations of >1.5 pH units and changes extending over 100's of micrometers from nanoconstrictions. The degree of change depends on key system parameters including buffer composition, surface charge, and strength of electric field. The results highlight the importance of neglected contributions of pH changes, and the approach can aid characterization and manipulation of mass transport in nanofluidic systems. © 2012 American Chemical Society.

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A distributed approach to taming peak demand

2012 International Green Computing Conference, IGCC 2012

Sabolish, Michael; Amer, Ahmed; Kroeger, Thomas

A significant portion of all energy capacity is wasted in over-provisioning to meet peak demand. The current state-of-the-art in reducing peak demand requires central authorities to limit device usage directly, and are generally reactive. We apply techniques drawn from established distributed computing principles to propose a novel and proactive solution to decentralize management of demand and to provide a more scalable and resilient approach to reducing overall peak demand. We demonstrate that such a system approaches the performance of an ideal centralized control authority, and experimentally demonstrate a 10-25% reduction in peak energy demand under conservative assumptions. Under worst-case demand scenarios, our approach has the potential to reduce peak demand by 65-85%. © 2012 IEEE.

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Arc-fault detector algorithm evaluation method utilizing prerecorded arcing signatures

Conference Record of the IEEE Photovoltaic Specialists Conference

Johnson, Jay; Kang, Jack

The 2011 National Electrical Code® Article 690.11 requires photovoltaic systems on or penetrating a building to include a DC arc-fault protection device. In order to satisfy this requirement, new Arc-Fault Detectors (AFDs) are being developed by multiple manufacturers including Sensata Technologies. Arc-fault detection algorithms often utilize the AC noise on the PV string to determine when arcing conditions exist in the DC system. In order to accelerate the development and testing of Sensata Technologies' arc-fault detection algorithm, Sandia National Laboratories (SNL) provided a number of data sets. These prerecorded 10 MHz baseline and arc-fault data sets included different inverter and arc-fault noise signatures. Sensata Technologies created a data evaluation method focused on regeneration of the prerecorded arcing and baseline test data with an arbitrary function generator, thereby reducing AFD development time. © 2012 IEEE.

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Evaluation of alternatives to the FERC SGIP screens for PV interconnection studies

Conference Record of the IEEE Photovoltaic Specialists Conference

Broderick, Robert J.; Ellis, Abraham

Existing screening procedures contained in state and federal interconnection rules are designed to balance the need for efficiency and technical rigor for all Distributed Generation (DG). The interconnection of DG that pose no risk of system impacts based on the screens can be expedited without the need for further studies. While the interconnection screening procedures have served the industry well, they also need to evolve in order to remain relevant with respect to evolving standards, technology, and practical experience. This is particularly important considering the large and increasing volume of DG applications, particularly photovoltaic (PV) generation. This paper discusses the application of two screens from the point of view of PV: the 15% penetration on line sections and the 20 kW aggregate capacity screen for single-phase secondary circuits. We discuss extensions to the existing interconnection screens that allow for a more rigorous upfront technical evaluation to identify potential system impacts, based on the characteristics of PV generation. More effective and efficient screens will allow utilities to focus the interconnection study effort for PV systems on the cases most likely to impact the electric distribution system and avoid unnecessary interconnection study costs and delays. © 2012 IEEE.

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Photovoltaic prognostics and heath management using learning algorithms

Conference Record of the IEEE Photovoltaic Specialists Conference

Riley, Daniel; Johnson, Jay

A novel model-based prognostics and health management (PHM) system has been designed to monitor the health of a photovoltaic (PV) system, measure degradation, and indicate maintenance schedules. Current state-of-the-art PV monitoring systems require module and array topology details or extensive modeling of the PV system. We present a method using an artificial neural network (ANN) which eliminates the need for a priori information by teaching the algorithm "good" performance behavior based on the initial performance of the array. The PHM algorithm was tested on two PV systems under test at the Outdoor Test Facility (OTF) at the National Renewable Energy Laboratory (NREL). The PHM algorithm was trained using two months of AC power production. The model then predicted the output power of the system using irradiance, wind, and temperature data. Based on the deviation in measured AC power from the AC power predicted by the trained ANN model, system outages and other faults causing a reduction in power were detected. Had these been commercial installations, rather than research installations, an alert for maintenance could have been initiated. Further use of the PHM system may be able to indicate degradation, detect module or inverter failures, or detect excessive soiling. © 2012 IEEE.

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Simulation and experimental characterization of the point spread function, pixel saturation, and blooming of a mercury cadmium telluride focal plane array

Applied Optics

Soehnel, Grant; Tanbakuchi, Anthony

A custom IR spot scanning experiment was constructed to project subpixel spots on a mercury cadmium telluride focal plane array (FPA). The hardware consists of an FPA in a liquid nitrogen cooled Dewar, high precision motorized stages, a custom aspheric lens, and a 1.55 and 3.39 laser source. By controlling the position and intensity of the spot, characterizations of cross talk, saturation, blooming, and (indirectly) the minority carrier lifetime were performed. In addition, a Monte–Carlo-based charge diffusion model was developed to validate experimental data and make predictions. Results show very good agreement between the model and experimental data. Parameters such as wavelength, reverse bias, and operating temperature were found to have little effect on pixel crosstalk in the absorber layer of the detector. Saturation characterizations show that these FPAs, which do not have antiblooming circuitry, exhibit an increase in cross talk due to blooming at ∼39% beyond the flux required for analog saturation. © 2012 Optical Society of America.

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Computing Stackelberg equilibria in discounted stochastic games

Proceedings of the National Conference on Artificial Intelligence

Vorobeychik, Yevgeniy; Singh, Satinder

Stackelberg games increasingly influence security policies deployed in real-world settings. Much of the work to date focuses on devising a fixed randomized strategy for the defender, accounting for an attacker who optimally responds to it. In practice, defense policies are often subject to constraints and vary over time, allowing an attacker to infer characteristics of future policies based on current observations. A defender must therefore account for an attacker's observation capabilities in devising a security policy. We show that this general modeling framework can be captured using stochastic Stackelberg games (SSGs), where a defender commits to a dynamic policy to which the attacker devises an optimal dynamic response. We then offer the following contributions. 1) We show that Markov stationary policies suffice in SSGs, 2) present a finite-time mixed-integer non-linear program for computing a Stackelberg equilibrium in SSGs, and 3) present a mixed-integer linear program to approximate it. 4) We illustrate our algorithms on a simple SSG representing an adversarial patrolling scenario, where we study the impact of attacker patience and risk aversion on optimal defense policies. Copyright © 2012, Association for the Advancement of Artificial Intelligence. All rights reserved.

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A starting point for negotiations - Delivering with a heterogeneous team

Proceedings - 2012 Agile Conference, Agile 2012

Lorber, Alfred; Tieszen, Sheldon R.

This paper presents a counterintuitive Pre-Sprint Work Balancing methodology that has substantially increased the ability of our highly heterogeneous Scrum [1] team to deliver what it promises at the end of each sprint. The process essentially consists of preplanning steps that acknowledge both the heterogeneity in developer's time and skill level, as well as Product Owner priorities. These preplanning activities act as a starting point for negotiations with the team during the Sprint Planning Meeting. For our team, delivery of all promised tasks in a sprint has increased from less than 1/3 of our sprints to more than 2/3, with indications that we are heading towards nearly 100% delivery. © 2012 IEEE.

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Application of FIB/SEM/EDXS tomographic spectral imaging and multivariate statistical analysis to the analysis of localized corrosion

2012 IEEE Statistical Signal Processing Workshop, SSP 2012

Kotula, Paul G.; Van Benthem, Mark H.; Sorensen, Neil R.

Tomographic spectral imaging is a powerful technique for the 3D analysis of materials. The present work describes the application of this technique to the analysis of localized corrosion of a connector pin. Implemented via serial sectioning in a focused ion-beam/scanning electron microscope, electron-excited x-ray spectra were acquired from each voxel in a 3D array. The resultant tomographic spectral image was analyzed in its entirety with Sandia's Automated eXpert Spectral Image Analysis multivariate statistical analysis software. The result of the analysis is a small number of chemical components which describe the 3D phase distribution in the volume of material sampled. © 2012 IEEE.

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Highly parameterized inverse estimation of hydraulic conductivity and porosity in a three-dimensional, heterogeneous transport experiment

Water Resources Research

Yoon, Hongkyu; Mckenna, Sean A.

Assessing the impact of parameter estimation accuracy in models of heterogeneous, three-dimensional (3-D) groundwater systems is critical for predictions of solute transport. A unique experimental data set provides concentration breakthrough curves (BTCs) measured at a 0.253 cm 3 scale over the 13 × 8 × 8 cm3 domain (∼53,000 measurement locations). Advective transport is used to match the first temporal moments of BTCs (or mean arrival times, m1) averaged at 0.253 and 1.0 cm3 scales through simultaneous inversion of highly parameterized heterogeneous hydraulic conductivity (K) and porosity (φ) fields. Pilot points parameterize the fields within eight layers of the 3-D medium, and estimations are completed with six different models of the K-φ relationship. Parameter estimation through advective transport shows accurate estimation of the observed m1 values. Results across the six different K-φ relationships have statistically similar fits to the observed m1 values and similar spatial estimates of m1 along the main flow direction. The resulting fields provide the basis for forward transport modeling of the advection-dispersion equation (ADE). Using the estimated K and φ fields demonstrates that advective transport coupled with inversion using dense spatial field parameterization provides an efficient surrogate for the ADE. These results indicate that there is not a single set of model parameters, or a single K-φ relationship, that leads to a best representation of the actual experimental sand packing pattern (i.e., nonuniqueness). Additionally, knowledge of the individual sand K and values along with their arrangement in the 3-D experiment does not reproduce the observed transport results at small scales. Small-scale variation in the packing and mixing of the sands causes large deviations from the expected transport results as highlighted in forward ADE simulations. Highly parameterized inverse estimation is able to identify those regions where variations in mixing and packing alter the expected property values and significantly improve results relative to the nave application of the experimentally derived property values. Impacts of the observation scale, the scale over which results are averaged and the number of observations and parameters on the final estimations are also examined. Results indicate existence of a representative element volume (REV) at 0.25 cm3, the existence of subgrid scale heterogeneity that impacts transport and the accuracy of highly parameterized models with even relatively small amounts of observations. Finally, this work suggests that local-heterogeneity features below the REV scale are difficult to incorporate into parameterized models, highlighting the importance of addressing prediction uncertainty for small-scale variability (i.e., uncaptured variability) in modeling practice. © 2012. American Geophysical Union. All Rights Reserved.

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An examination of fuel consumption trends in construction projects

Energy Policy

Hines, Valerie A.; Manley, Dawn K.

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Cationic cure kinetics of a polyoxometalate loaded epoxy nanocomposite

Journal of Polymer Science, Part A: Polymer Chemistry

Anderson, Benjamin J.

The reaction cure kinetics of a novel polyoxometalate (POM) loaded epoxy nanocomposite is described. The POM is dispersed in the epoxy resin up to volume fractions of 0.1. Differential scanning calorimetry measurements show the cure of the epoxy resin to be sensitive to the POM loading. A kinetics study of the cure exotherm confirms that POM acts as a catalyst promoting cationic homopolymerization of the epoxy resin. The cure reaction is shown to propagate through two cure regimes. A fast cure at short time is shown to be propagation by the activated chain end (ACE) mechanism. A slow cure at long time is shown to be propagation by the activated monomer (AM) mechanism. The activation energies for the fast and slow cure regimes agree well with other epoxy based systems that have been confirmed to propagate by the ACE and AM mechanisms.© 2012 Wiley Periodicals, Inc.

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Turbulence of a fin trailing vortex in subsonic compressible flow

AIAA Journal

Beresh, Steven J.; Henfling, John F.; Spillers, Russell

Stereoscopic Particle Image Velocimetry data of a trailing vortex shed from a tapered fin installed on a wind-tunnel wall have been analyzed to provide turbulent statistics. After correcting for the effects of vortex meander, the radial and azimuthal turbulent normal stresses are smallest at the vortex center, reaching a maximum around its periphery to produce an annulus of turbulence. Conversely, the streamwise turbulent stress peaks at the vortex center. The ringed turbulent structure is consistent with rotation stabilizing the flow in the vortex core, whereas a fluctuating axial velocity contributes to vortex decay. All three turbulent normal stresses decay with downstream distance. Turbulent shear stresses also decay with downstream distance but possess a relatively small magnitude, suggesting minimal coupling between turbulent velocity components. The vortex turbulence is strongly anisotropic in a manner that varies greatly with spatial position. As the vortex strength is reduced, the axial turbulent normal stress diminishes more sharply than the two cross-plane turbulent normal stresses, possibly because the latter components are influenced by external turbulence spiraling towards the vortex core. The turbulent shear stresses do not show discernable reductions in magnitude with lower vortex strength.

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Polar Format Algorithm: Survey of Assumptions and Approximations

Musgrove, Cameron

Since the Polar Format Algorithm (PFA) was first introduced by Jack Walker 30 years ago, digital processing and Moore’s law have provided the means by which to process an increasing amount of data, at finer resolutions, over a larger area, and in real-time. Inherent in the polar format algorithm are assumptions that limit the focused scene size. This report presents a development of PFA for a linear frequency modulated chirp pulsed radar utilizing stretch processing to illustrate how PFA approximations are used to form an image. Also techniques to mitigate the errors resulting from the approximations are presented from a survey of literature sources. There are many techniques that are successful at increasing the focused scene size, these include image corrections made after image formation, subaperture processing, and careful selection of processing coordinates. This report only considers methods that use the polar format algorithm.

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The Portals 4.0 Network Programming Interface

Brightwell, Ronald B.; Pedretti, Kevin; Wheeler, Kyle B.; Hemmert, Karl S.; Barrett, Brian

This report presents a specification for the Portals 4.0 network programming interface. Portals 4.0 is intended to allow scalable, high-performance network communication between nodes of a parallel computing system. Portals 4.0 is well suited to massively parallel processing and embedded systems. Portals 4.0 represents an adaption of the data movement layer developed for massively parallel processing platforms, such as the 4500-node Intel TeraFLOPS machine. Sandia’s Cplant cluster project motivated the development of Version 3.0, which was later extended to Version 3.3 as part of the Cray Red Storm machine and XT line. Version 4.0 is targeted to the next generation of machines employing advanced network interface architectures that support enhanced offload capabilities.

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Results 60601–60800 of 99,299
Results 60601–60800 of 99,299