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Viscoelastic material inversion using Sierra-SD and ROL

Walsh, Timothy; Aquino, Wilkins; Ridzal, Denis; Kouri, Drew P.; Van Bloemen Waanders, Bart; Urbina, Angel U.

In this report we derive frequency-domain methods for inverse characterization of the constitutive parameters of viscoelastic materials. The inverse problem is cast in a PDE-constrained optimization framework with efficient computation of gradients and Hessian vector products through matrix free operations. The abstract optimization operators for first and second derivatives are derived from first principles. Various methods from the Rapid Optimization Library (ROL) are tested on the viscoelastic inversion problem. The methods described herein are applied to compute the viscoelastic bulk and shear moduli of a foam block model, which was recently used in experimental testing for viscoelastic property characterization.

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TYPE SAND Report YEAR 2014
DOIOSTI

Active Control of Nitride Plasmonic Dispersion in the Far Infrared

Shaner, Eric A.; Dyer, Gregory C.; Seng, William F.; Bethke, Donald; Grine, Albert; Baca, Albert G.; Allerman, A.A.

We investigate plasmonic structures in nitride-based materials for far-infrared (IR) applications. The two dimensional electron gas (2DEG) in the GaN/AlGaN material system, much like metal- dielectric structures, is a patternable plasmonic medium. However, it also permits for direct tunability via an applied voltage. While there have been proof-of-principle demonstrations of plasma excitations in nitride 2DEGs, exploration of the potential of this material system has thus far been limited. We recently demonstrated coherent phenomena such as the formation of plasmonic crystals, strong coupling of tunable crystal defects to a plasmonic crystal, and electromagnetically induced transparency in GaAs/AlGaAs 2DEGs at sub-THz frequencies. In this project, we explore whether these effects can be realized in nitride 2DEG materials above 1 THz and at temperatures exceeding 77 K.

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TYPE SAND Report YEAR 2014
DOIOSTI

Ultrafast Laser Diagnostics for Energetic-Material Ignition Mechanisms: Tools for Physics-Based Model Development

Kearney, Sean P.; Jilek, Brook A.; Kohl, Ian T.; Farrow, Darcie; Urayama, Junji

We present the results of an LDRD project to develop diagnostics to perform fundamental measurements of material properties during shock compression of condensed phase materials at micron spatial scales and picosecond time scales. The report is structured into three main chapters, which each focus on a different diagnostic devel opment effort. Direct picosecond laser drive is used to introduce shock waves into thin films of energetic and inert materials. The resulting laser - driven shock properties are probed via Ultrafast Time Domain Interferometry (UTDI), which can additionally be used to generate shock Hugoniot data in tabletop experiments. Stimulated Raman scattering (SRS) is developed as a temperature diagnostic. A transient absorption spectroscopy setup has been developed to probe shock - induced changes during shock compressio n. UTDI results are presented under dynamic, direct - laser - drive conditions and shock Hugoniots are estimated for inert polystyrene samples and for the explosive hexanitroazobenzene, with results from both Sandia and Lawrence Livermore presented here. SRS a nd transient absorption diagnostics are demonstrated on static thin - film samples, and paths forward to dynamic experiments are presented.

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TYPE SAND Report YEAR 2014
DOIOSTI

Design Process Overview

Halkjaer-Knudsen, Vibeke N.

For the purposes of this paper, a Biocontainment facility is a laboratory, production facility, or similar building that handles contagious biological materials in a safe and responsible manner. This specialized facility, also called a containment facility or a high containment facility reduces the potential for biological agents to be released into the environment, provides a safe work environment for the employees, and supports good laboratory practices.

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TYPE Other Report YEAR 2014
DOIOSTI

Precision circuit calculations in hostile environments

Sandia journal manuscript; Not yet accepted for publication

Hembree, Charles; Keiter, Eric R.

Sensing and calculating electronic systems with stringent accuracy requirements use internal standard voltages for references. Conceptually, this is related to using some unit measurement for counting any quantity. The high precision electronic components used in systems in the nation’s stockpile also make use of these standard voltages. The need for stable voltage references has been long-standing in the overall electronics industry. For many applications, the most pressing need is for stability of a reference voltage as the circuit temperature varies. Typical circuit components have temperature coefficients for their operational characteristics that are given in some delta per degree centigrade and these coefficients can be either positive or negative. Thus, it is natural to consider building a circuit out of components that have complementary temperature coefficients so that the operating characteristics of the circuit have a net zero temperature coefficient. This is the fundamental basis of precision voltage reference (PVR) circuit operation and it is straightforward to extend this type of stabilization to reduce shifts caused by hostile environment radiation.

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TYPE Journal Article YEAR 2014
OSTI

Comparison of Aleph and BOLSIG+ Results for Electron-Nitrogen Chemistry

Hopkins, Matthew M.; Crozier, Paul; Moore, Christopher H.

The goal of this report is to document the current status of Aleph with regards to electron collisions under an electric field. Aleph and the community-accepted BOLSIG+ code are both used to compute reactions rates for a set of 25 electron-nitrogen interactions. A reasonable comparison is found (see below) providing evidence that Aleph is successfully simulating or implementing: (1) Particle-particle collision cross-sections via DSMC methodology, (2) Energy balance for simple particle interactions, and (3) Electron energy distribution function (EEDF) evolution

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TYPE SAND Report YEAR 2014
DOIOSTI

Adaptive Beam Smoothing with Plasma-Pinholes for Laser-Entrance-Hole Transmission Studies

Geissel, Matthias; Awe, Thomas J.; Campbell, Edward M.; Gomez, Matthew R.; Harding, Eric H.; Harvey-Thompson, Adam J.; Jennings, Christopher A.; Kimmel, Mark; Lewis, Sean M.; Mcbride, Ryan; Peterson, K.J.; Schollmeier, Marius; Sefkow, Adam B.; Shores, Jonathon; Sinars, Daniel; Slutz, Stephen A.; Smith, Ian C.; Speas, Christopher S.; Stahoviak, John W.; Porter, John L.

Abstract not provided.

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TYPE Conference Poster YEAR 2014
OSTI

Attaining and Maintaining a Continuity of Knowledge to Draw Safeguards Conclusions with Confidence

ESARDA Bulletin

Blair, Dianna S.; Pickett, Chris; Bean, Robert

As the 21st century progresses, new nuclear facilities and the expansion of nuclear activities into new countries will require the International Atomic Energy Agency (IAEA) to place a higher reliance on attaining and maintaining a Continuity of Knowledge (CoK) of its safeguards information than is currently practiced. Additionally, a conceptual view of where and how CoK can be applied will need to evolve to support improved efficiency and efficacy of drawing a safeguards conclusion for each Member State. The ability to draw a safeguards conclusion for a Member State will be predicated on the confidence that CoK has been attained and subsequently maintained with respect to the data and information streams used by the IAEA. This confidence can be described as a function of factors such as elapsed time since the measurement, surveillance of attributes, authentication of information, historic knowledge of potential system failures, and the number and type of data collections. A set of general scenarios are further described for determining what is required to attain CoK and whether CoK has been maintained. A high-level analysis of example scenarios is presented to identify failures or gaps that could cause a loss of CoK. Potential areas for technological research and development are discussed for the next generation of CoK tools.

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TYPE Journal Article YEAR 2014
OSTI

Structural Changes of Self-Assembled Leas Sulfide, Polystyrene Thin Films Under Extreme Pressure Using in-situ High Pressure Small Angle X-ray Scattering

Pepple, Mark; Hill, Joshua

Polymer nanocomposite films consisting of polystyrene (PS) and lead sulfide (PbS) quantum dots, as well as pure PbS quantum dot films were synthesized for the purpose of investigating the pressure directed assembly (PDA) of the nanomaterials and the interactions of polystyrene and the quantum dot superlattice under pressure. Samples were compressed using a diamond anvil cell (DAC) to pressures greater than 15 GPa and studied using x-ray synchrotron radiation in order to show the changes in the d-spacing of the superlattice with respect to pressure. Absorption characteristics were investigated with ultraviolet visible spectroscopy (UV/Vis), while structure and long range ordering of the lattice were studied using small angle x-ray scattering (SAXS) as well as grazing incidence small angle scattering (GISAXS). Particle size was examined with transmission electron microscopy (TEM). These inquiries into size, structure, and interactions were performed in order to gain a baseline understanding of the interplay between nanoparticles and a simple polymer in a composite system and how the composite systems can be composed in future experiments.

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TYPE Other Report YEAR 2014
DOIOSTI

Addressing Modeling Requirements for Radiation Heat Transfer

Tencer, John T.; Akau, Ron L.; Dobranich, Dean; Brown, Alexander L.; Dodd, Amanda B.; Foulk, James W.; Okusanya, Tolulope O.; Phinney, Leslie; Pierce, Flint

Thermal analysts address a wide variety of applications requiring the simulation of radiation heat transfer phenomena. There are gaps in the currently available modeling capabilities. Addressing these gaps would allow for the consideration of additional physics and increase confidence in simulation predictions. This document outlines a five year plan to address the current and future needs of the analyst community with regards to modeling radiation heat transfer processes. This plan represents a significant multi-year effort that must be supported on an ongoing basis.

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TYPE SAND Report YEAR 2014
DOIOSTI

Time-Encoded Imagers

Marleau, P.; Brubaker, E.

This report provides a short overview of the DNN R&D funded project, Time-Encoded Imagers. The project began in FY11 and concluded in FY14. The Project Description below provides the overall motivation and objectives for the project as well as a summary of programmatic direction. It is followed by a short description of each task and the resulting deliverables.

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TYPE SAND Report YEAR 2014
DOIOSTI

Low-Cost Spectral Sensor Development Description

Armijo, Kenneth M.; Yellowhair, Julius

Solar spectral data for all parts of the US is limited due in part to the high cost of commercial spectrometers. Solar spectral information is necessary for accurate photovoltaic (PV) performance forecasting, especially for large utility-scale PV installations. A low-cost solar spectral sensor would address the obstacles and needs. In this report, a novel low-cost, discrete-band sensor device, comprised of five narrow-band sensors, is described. The hardware is comprised of commercial-off-the-shelf components to keep the cost low. Data processing algorithms were developed and are being refined for robustness. PV module short-circuit current ($I_{sc}$) prediction methods were developed based on interaction-terms regression methodology and spectrum reconstruction methodology for computing $I_{sc}$. The results suggest the computed spectrum using the reconstruction method agreed well with the measured spectrum from the wide-band spectrometer (RMS error of 38.2 W/m2 -nm). Further analysis of computed $I_{sc}$ found a close correspondence of 0.05 A RMS error. The goal is for ubiquitous adoption of the low-cost spectral sensor in solar PV and other applications such as weather forecasting.

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TYPE SAND Report YEAR 2014
DOIOSTI

Photovoltaic Microinverter Testbed for Multiple Device Interoperability

Quiroz, Jimmy E.; Gonzalez, Sigifredo; King, Bruce H.; Riley, Daniel; Johnson, Jay; Stein, Joshua

IEEE Standard 1547-2003 conformance of several interconnected microinverters was performed by Sandia National Laboratories (SNL) to determine if there were emergent adverse behaviors of co-located aggregated distributed energy resources. Experiments demonstrated the certification tests could be expanded for multi-manufacturer microinverter interoperability. Evaluations determined the microinverters' response to abnormal conditions in voltage and frequency, interruption in grid service, and cumulative power quality. No issues were identified to be caused by the interconnection of multiple devices.

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TYPE SAND Report YEAR 2014
DOIOSTI

Programming Abstractions for Data Locality

Tate, Adrian; Kamil, Amir; Dubey, Anshu; Groblinger, Armin; Chamberlain, Brad; Goglin, Brice; Edwards, Harold C.; Newburn, Chris J.; Padua, David; Unat, Didem; Jeannot, Emmanuel; Hannig, Frank; Tobias, Gysi; Ltaief, Hatem; Sexton, James; Labarta, Jesus; Shalf, John; Fuerlinger, Karl; Brien, Leonidas'; Linardakis, Leonidas; Besta, MacIej; Sawley, Marie-Christine; Abraham, Mark; Bianco, Mauro; Pericas, Miquel; Maruyama, Naoya; Kelly, Paul H.J.; Messmer, Peter; Ross, Robert B.; Ciedat, Romain; Matsuoka, Satoshi; Schulthess, Thomas; Hoefler, Torsten; Leung, Vitus J.

The goal of the workshop and this report is to identify common themes and standardize concepts for locality-preserving abstractions for exascale programming models.

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TYPE Other Report YEAR 2014
DOIOSTI

Evaluation of the Tellabs 1150 GPON multiservice access platform

Brenkosh, Joseph P.; Wolf, Jimmie V.

For over two years, Sandia National Laboratories has been using a Gigabit Passive Optical Network (GPON) access layer for selected networks. The GPON equipment includes the Tellabs 1150 Multiservice Access Platform (MSAP) Optical Line Terminal (OLT), the Tellabs ONT709 and ONT709GP Optical Network Terminals (ONTs), and the Panorama PON Network Manager. In late 2013, the Tellabs equipment was updated to Software Release FP27.1_015130. Because a new software release has the potential to affect performance and functionality, it needed to be thoroughly tested. This report documents that testing. It also provides a comparison between the current release and the previous Software Release FP25.5.1_013274 that was being used.

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TYPE SAND Report YEAR 2014
DOIOSTI

Finding Hierarchical and Overlapping Dense Subgraphs using Nucleus Decompositions

Comandur, Seshadhri; Pinar, Ali P.; Sariyuce, Ahmet E.; Catalyurek, Umit

Finding dense substructures in a graph is a fundamental graph mining operation, with applications in bioinformatics, social networks, and visualization to name a few. Yet most standard formulations of this problem (like clique, quasiclique, k-densest subgraph) are NP-hard. Furthermore, the goal is rarely to nd the \true optimum", but to identify many (if not all) dense substructures, understand their distribution in the graph, and ideally determine a hierarchical structure among them. Current dense subgraph nding algorithms usually optimize some objective, and only nd a few such subgraphs without providing any hierarchy. It is also not clear how to account for overlaps in dense substructures. We de ne the nucleus decomposition of a graph, which represents the graph as a forest of nuclei. Each nucleus is a subgraph where smaller cliques are present in many larger cliques. The forest of nuclei is a hierarchy by containment, where the edge density increases as we proceed towards leaf nuclei. Sibling nuclei can have limited intersections, which allows for discovery of overlapping dense subgraphs. With the right parameters, the nuclear decomposition generalizes the classic notions of k-cores and k-trusses. We give provable e cient algorithms for nuclear decompositions, and empirically evaluate their behavior in a variety of real graphs. The tree of nuclei consistently gives a global, hierarchical snapshot of dense substructures, and outputs dense subgraphs of higher quality than other state-of-theart solutions. Our algorithm can process graphs with tens of millions of edges in less than an hour.

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TYPE Other Report YEAR 2014
DOIOSTI
Results 50601–50800 of 99,299
Results 50601–50800 of 99,299