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Photoacoustic Sounds from Meteors

Sandia journal manuscript; Not yet accepted for publication

Spalding, Richard; Tencer, John T.; Sweatt, W.C.; Foulk, James W.; Boslough, Mark; Gonzales, Gigi

High-speed photometric observations of meteor fireballs have shown that they often produce high-amplitude light oscillations with frequency components in the kHz range, and in some cases exhibit strong millisecond flares. We built a light source with similar characteristics and illuminated various materials in the laboratory, generating audible sounds. Models suggest that light oscillations and pulses can radiatively heat dielectric materials, which in turn conductively heats the surrounding air on millisecond timescales. The sound waves can be heard if the illuminated material is sufficiently close to the observer’s ears. The mechanism described herein may explain many reports of meteors that appear to be audible while they are concurrently visible in the sky and too far away for sound to have propagated to the observer. This photoacoustic (PA) explanation provides an alternative to electrophonic (EP) sounds hypothesized to arise from electromagnetic coupling of plasma oscillation in the meteor wake to natural antennas in the vicinity of an observer.

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TYPE Journal Article YEAR 2015
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The 2014 Sandia Nonlinear Mechanics and Dynamics Summer Research Institute

Brake, M.R.W.; Reuss, Pascal; Schwingshackl, Christoph W.; Salles, Loic; Negus, Michaela; Peebles, Diane; Mayes, Randall L.; Bilbao-Ludena, Juan-Carlos; Bonney, Matthew S.; Catalfamo, Simone; Gastaldi, Chiara; Gross, Johann; Lacayo, Robert M.; Robertson, Brett A.; Smith, Scott; Swacek, Christian; Tiedemann, Merten

A collaborative research institute was organized and held at Sandia Albuquerque for a period of six weeks. This research institute brought together researchers from around the world to work collaboratively on a set of research projects. These research projects included: developing experimental guidelines for studying variability and repeatability of nonlinear structures; decoupling aleatoric and epistemic uncertainty in measurements to improve dynamic predictions; a numerical round robin to assess the performance of five different numerical codes for modeling systems with strong nonlinearities; and an assessment of experimentally derived and numerically derived reduced order models. In addition to the technical collaborations, the institute also included a series of seminars given by both Sandians and external experts, as well as a series of tours and field trips to local places of scientific and engineering importance. This report details both the technical research and the programmatic organization of the 2014 Sandia Nonlinear Mechanics and Dynamics Summer Research Institute.

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TYPE SAND Report YEAR 2015
DOIOSTI

Dominion. A game exploring information exploitation

Hobbs, Jacob; Estrada, Trilce

FlipIt is a game theoretic framework published in 2012[1] to investigate optimal strategies for managing security resources in response to Advanced Persistent Threats. It is a two-player game wherein a resource is controlled by exactly one player at any time. A player may move at any time to capture the resource, incurring a move cost, and is informed of the last time their opponent has moved only upon completing their move. Thus, moves may be wasted and takeover is considered \stealthy", with regard to the other player. The game is played for an unlimited period of time, and the goal of each player is to maximize the amount of time they are in control of the resource minus their total move cost, normalized by the current length of play. Marten Van Dijk and others[1] provided an analysis of various player strategies and proved optimal results for certain subclasses of players. We extend their work by providing a reformulation of the original game, wherein the optimal player strategies can be solved exactly, rather than only for certain subclasses. We call this reformulation Dominion, and place it within a broader framework of stealthy move games. We de ne Dominion to occur over a nite time scale (from 0 to 1), and give each player a certain number of moves to make within the time frame. Their expected score in this new scenario is the expected amount of time they have control, and the point of the game is to dominate as much of the unit interval as possible. We show how Dominion can be treated as a two player, simultaneous, constant sum, unit square game, where the gradient of the bene t curves for the players are linear and possibly discontinuous. We derive Nash equilibria for a basic version of Dominion, and then further explore the roles of information asymmetry in its variants. We extend these results to FlipIt and other cyber security applications.

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TYPE Thesis or Dissertation YEAR 2015
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CCC7-119 Reactive Molecular Dynamics Simulations of Hot Spot Growth in Shocked Energetic Materials

Thompson, A.P.

The purpose of this work is to understand how defects control initiation in energetic materials used in stockpile components; Sequoia gives us the core-count to run very large-scale simulations of up to 10 million atoms and; Using an OpenMP threaded implementation of the ReaxFF package in LAMMPS, we have been able to get good parallel efficiency running on 16k nodes of Sequoia, with 1 hardware thread per core.

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TYPE Other Report YEAR 2015
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Ensuring a Viable Future for the Weapons Laboratories

Exchange Monitor

Buican, Ileana G.

As recognized by the Mies-Augustine report (A New Foundation for the Nuclear Enterprise, Report of the Congressional Advisory Panel on the Governance of the Nuclear Security Enterprise, Nov. 2014), any consideration of governance must begin with an understanding of mission. At first glance, the mission of these three laboratories seems obvious: We are national security laboratories with the core mission being our support of nuclear deterrence. This is certainly true. However, there are nuances here that I believe are very important to consider. Furthermore, I suspect that, if I were to ask you what a “national security laboratory” means, I would get a wide variety of answers.

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TYPE Journal Article YEAR 2015
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An Elastic Plastic Contact Model with Strain Hardening for the LAMMPS Granular Package

Kuhr, Bryan; Brake, M.R.W.; Lechman, Jeremy B.

The following details the implementation of an analytical elastic plastic contact model with strain hardening for normal im pacts into the LAMMPS granular package. The model assumes that, upon impact, the co llision has a period of elastic loading followed by a period of mixed elastic plas tic loading, with contributions to each mechanism estimated by a hyperbolic seca nt weight function. This function is implemented in the LAMMPS source code as the pair style gran/ep/history. Preliminary tests, simulating the pouring of pure nickel spheres, showed the elastic/plastic model took 1.66x as long as similar runs using gran/hertz/history.

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TYPE SAND Report YEAR 2015
DOIOSTI

Laboratory Building

Herrera, Joshua M.

This report is an analysis of the means of egress and life safety requirements for the laboratory building. The building is located at Sandia National Laboratories (SNL) in Albuquerque, NM. The report includes a prescriptive-based analysis as well as a performance-based analysis. Following the analysis are appendices which contain maps of the laboratory building used throughout the analysis. The top of all the maps is assumed to be north.

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TYPE Other Report YEAR 2015
DOIOSTI

Parameter Estimation for Single Diode Models of Photovoltaic Modules

Hansen, Clifford

Many popular models for photovoltaic system performance employ a single diode model to compute the I - V curve for a module or string of modules at given irradiance and temperature conditions. A single diode model requires a number of parameters to be estimated from measured I - V curves. Many available parameter estimation methods use only short circuit, o pen circuit and maximum power points for a single I - V curve at standard test conditions together with temperature coefficients determined separately for individual cells. In contrast, module testing frequently records I - V curves over a wide range of irradi ance and temperature conditions which, when available , should also be used to parameterize the performance model. We present a parameter estimation method that makes use of a fu ll range of available I - V curves. We verify the accuracy of the method by recov ering known parameter values from simulated I - V curves . We validate the method by estimating model parameters for a module using outdoor test data and predicting the outdoor performance of the module.

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TYPE SAND Report YEAR 2015
DOIOSTI

Sandia_HighTemperatureComponentEvaluation_2015

Cashion, Avery T.

The objective of this project is to perform independent evaluation of high temperature components to determine their suitability for use in high temperature geothermal tools. Development of high temperature components has been increasing rapidly due to demand from the high temperature oil and gas exploration and aerospace industries. Many of these new components are at the late prototype or first production stage of development and could benefit from third party evaluation of functionality and lifetime at elevated temperatures. In addition to independent testing of new components, this project recognizes that there is a paucity of commercial-off-the-shelf COTS components rated for geothermal temperatures. As such, high-temperature circuit designers often must dedicate considerable time and resources to determine if a component exists that they may be able to knead performance out of to meet their requirements. This project aids tool developers by characterization of select COTS component performances beyond published temperature specifications. The process for selecting components includes public announcements of project intent (e.g., FedBizOps), direct discussions with candidate manufacturers,and coordination with other DOE funded programs.

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TYPE Other Report YEAR 2015
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Experimental Evaluation of the Free Piston Engine - Linear Alternator (FPLA)

Leick, Michael T.; Moses, Ronald W.

This report describes the experimental evaluation of a prototype free piston engine - linear alternator (FPLA) system developed at Sandia National Laboratories. The opposed piston design wa developed to investigate its potential for use in hybrid electric vehicles (HEVs). The system is mechanically simple with two - stroke uniflow scavenging for gas exchange and timed port fuel injection for fuel delivery, i.e. no complex valving. Electrical power is extracted from piston motion through linear alternators wh ich also provide a means for passive piston synchronization through electromagnetic coupling. In an HEV application, this electrical power would be used to charge the batteries. The engine - alternator system was designed, assembled and operated over a 2 - year period at Sandia National Laboratories in Livermore, CA. This report primarily contains a description of the as - built system, modifications to the system to enable better performance, and experimental results from start - up, motoring, and hydrogen combus tion tests.

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TYPE SAND Report YEAR 2015
DOIOSTI

ASC-ATDM Performance Portability Requirements for 2015-2019

Edwards, Harold C.; Trott, Christian R.

This report outlines the research, development, and support requirements for the Advanced Simulation and Computing (ASC ) Advanced Technology, Development, and Mitigation (ATDM) Performance Portability (a.k.a., Kokkos) project for 2015 - 2019 . The research and development (R&D) goal for Kokkos (v2) has been to create and demonstrate a thread - parallel programming model a nd standard C++ library - based implementation that enables performance portability across diverse manycore architectures such as multicore CPU, Intel Xeon Phi, and NVIDIA Kepler GPU. This R&D goal has been achieved for algorithms that use data parallel pat terns including parallel - for, parallel - reduce, and parallel - scan. Current R&D is focusing on hierarchical parallel patterns such as a directed acyclic graph (DAG) of asynchronous tasks where each task contain s nested data parallel algorithms. This five y ear plan includes R&D required to f ully and performance portably exploit thread parallelism across current and anticipated next generation platforms (NGP). The Kokkos library is being evaluated by many projects exploring algorithm s and code design for NGP. Some production libraries and applications such as Trilinos and LAMMPS have already committed to Kokkos as their foundation for manycore parallelism an d performance portability. These five year requirements includes support required for current and antic ipated ASC projects to be effective and productive in their use of Kokkos on NGP. The greatest risk to the success of Kokkos and ASC projects relying upon Kokkos is a lack of staffing resources to support Kokkos to the degree needed by these ASC projects. This support includes up - to - date tutorials, documentation, multi - platform (hardware and software stack) testing, minor feature enhancements, thread - scalable algorithm consulting, and managing collaborative R&D.

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TYPE SAND Report YEAR 2015
DOIOSTI

Submittal of SWMU Assessment Report for Building 9960 Surface Discharge

Dotson, Patrick W.

Sandia National Laboratories is a multi-purpose engineering and science laboratory owned by the U.S. Department of Energy (DOE)/National Nuclear Security Administration and managed and operated by Sandia Corporation (Sandia), a wholly-owned subsidiary of Lockheed Martin Corporation. This Solid Waste Management Unit (SWMU) Assessment Report (SAR) for the Sandia National Laboratories, New Mexico (SNL/NM), Coyote Test Field, Building 9960 Surface Discharge, has been prepared in accordance with Section V of the Compliance Order on Consent (the Consent Order) between the New Mexico Environment Department (NMED), DOE, and Sandia (NMED April 2004). The DOE and Sandia formally notified the NMED of this newly identified or suspected SWMU or Area of Concern (AOC) by letter dated December 9, 2014. This SAR is being submitted in accordance with the NMED Hazardous Waste Bureau (HWB) letter dated February 16, 2015 letter (Kieling February 2015). This SAR presents the available information for the Building 9960 Surface Discharge, including location, designation of type and function, a general description, the operational dates, waste characteristics, and a summary of existing analytical wastewater and soil data

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TYPE Other Report YEAR 2015
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FY14 Laboratory Directed Research and Development Annual Report

Chavez, Donna L.; Schunk, Peter R.

This report summarizes progress from the Laboratory Directed Research and Development (LDRD) program during fiscal year 2014. In addition to the programmatic and financial overview, the report includes progress reports from 419 individual R&D projects in 16 categories. Information for 176 projects in their final year is presented in a more comprehensive format, while for those 243 in their pre-final years, only an abstract is presented herein.

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TYPE Other Report YEAR 2015
DOIOSTI

Optimizing the Configuration of Sensor Networks to Detect Intruders

Sandia journal manuscript; Not yet accepted for publication

Brown, Nathanael J.K.; Jones, Katherine; Nozick, Linda; Xu, Ningxiong

This paper focuses on optimizing the selection and configuration of detection technologies to protect a target of interest. The ability of an intruder to simply reach the target is assumed to be sufficient to consider the security system a failure. To address this problem, we develop a game theoretic model of the strategic interactions between the system owner and a knowledgeable intruder. A decomposition-based exact method is used to solve the resultant model.

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TYPE Journal Article YEAR 2015
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2015 Neuro-Inspired Computational Elements (NICE) Workshop: Information Processing and Computation Systems beyond von Neumann/Turing Architecture and Moore’s Law Limits (Summary Report)

Okandan, Murat

The third Neuro-Inspired Computational Elements (NICE) Workshop was held February 23-25, 2015 in Albuquerque, New Mexico. The goal of the Workshop was to bring together researchers from different scientific disciplines and application areas to provide a common point from which to develop the next generation of information processing/computing architectures that go beyond stored program architecture and Moore’s Law limits.

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TYPE Other Report YEAR 2015
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On Bipartite Graphs Trees and Their Partial Vertex Covers

ACM Transactions on Algorithms

Caskurlu, Bugra; Mkrtchyan, Vahan; Parekh, Ojas D.; Subramani, K.

Graphs can be used to model risk management in various systems. Particularly, Caskurlu et al. in [7] have considered a system, which has threats, vulnerabilities and assets, and which essentially represents a tripartite graph. The goal in this model is to reduce the risk in the system below a predefined risk threshold level. One can either restricting the permissions of the users, or encapsulating the system assets. The pointed out two strategies correspond to deleting minimum number of elements corresponding to vulnerabilities and assets, such that the flow between threats and assets is reduced below the predefined threshold level. It can be shown that the main goal in this risk management system can be formulated as a Partial Vertex Cover problem on bipartite graphs. It is well-known that the Vertex Cover problem is in P on bipartite graphs, however; the computational complexity of the Partial Vertex Cover problem on bipartite graphs has remained open. In this paper, we establish that the Partial Vertex Cover problem is NP-hard on bipartite graphs, which was also recently independently demonstrated [N. Apollonio and B. Simeone, Discrete Appl. Math., 165 (2014), pp. 37–48; G. Joret and A. Vetta, preprint, arXiv:1211.4853v1 [cs.DS], 2012]. We then identify interesting special cases of bipartite graphs, for which the Partial Vertex Cover problem, the closely related Budgeted Maximum Coverage problem, and their weighted extensions can be solved in polynomial time. We also present an 8/9-approximation algorithm for the Budgeted Maximum Coverage problem in the class of bipartite graphs. We show that this matches and resolves the integrality gap of the natural LP relaxation of the problem and improves upon a recent 4/5-approximation.

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TYPE Journal Article YEAR 2015
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Results 49201–49400 of 99,299
Results 49201–49400 of 99,299