Publications

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A code, Charon, is described which simulates the effects that neutron damage has on silicon semiconductor devices. The code uses a stabilized, finite-element discretization of the semiconductor drift-diffusion equations. The mathematical model used to simulate semiconductor devices in both normal and radiation environments will be described. Modeling of defect complexes is accomplished by adding an additional drift-diffusion equation for each of the defect species. Additionally, details are given describing how Charon can efficiently solve very large problems using modern parallel computers. Comparison between Charon and experiment will be given, as well as comparison with results from commercially-available TCAD codes.

The Global Nuclear Energy Partnership fuels development program is currently developing metallic, oxide, and nitride fuel forms as candidate fuels for an Advanced Burner Reactor. The Advance Burner Reactor is being designed to fission actinides efficiently, thereby reducing the long-term storage requirements for spent fuel repositories. Small fuel samples are being fabricated and evaluated with different transuranic loadings and with extensive burnup using the Advanced Test Reactor. During the next several years, numerous fuel samples will be fabricated, evaluated, and tested, with the eventual goal of developing a transmuter fuel database that supports the down selection to the most suitable fuel type. To provide a comparative database of safety margins for the range of potential transmuter fuels, this report describes a plan to conduct a set of early transient tests in the Annular Core Research Reactor at Sandia National Laboratories. The Annular Core Research Reactor is uniquely qualified to perform these types of tests because of its wide range of operating capabilities and large dry central cavity which extents through the center of the core. The goal of the fuels testing program is to demonstrate that the design and fabrication processes are of sufficient quality that the fuel will not fail at its design limit--up to a specified burnup, power density, and operating temperature. Transient testing is required to determine the fuel pin failure thresholds and to demonstrate that adequate fuel failure margins exist during the postulated design basis accidents.

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While existing work in neural interfaces is largely geared toward the restoration of lost function in amputees or victims of neurological injuries, similar technology may also facilitate augmentation of healthy subjects. One example is the potential to learn a new, unnatural sense through a neural interface. The use of neural interfaces in healthy subjects would require an even greater level of safety and convenience than in disabled subjects, including reliable, robust bidirectional implants with highly-portable components outside the skin. We present our progress to date in the development of a bidirectional neural interface system intended for completely untethered use. The system consists of a wireless stimulating and recording peripheral nerve implant powered by a rechargeable battery, and a wearable package that communicates wirelessly both with the implant and with a computer or a network of independent sensor nodes. Once validated, such a system could permit the exploration of increasingly realistic use of neural interfaces both for restoration and for augmentation. © 2007 IEEE.

Accurate, periodic calibration is required to operate IMS, GC, and portal security systems with maximum efficiency, surety, and operator confidence. To this end, we are presently developing a microfabricated device for on-demand calibration of fleldable contraband detection instruments. Using robotically-assisted picoliter dispensing methods, precise nanogram or larger amounts of calibration compound(s) are placed on micron-sized bridge structures. Resistively heating these structures delivers precisely quantified low-levels of calibration compounds to the detector systems. This provides reliable calibration for identification and quantification of explosives, narcotics, and other contraband. © 2007 IEEE.

S-Learning is a sequence-based learning algorithm patterned on human motor behavior. Discrete-time and quantized sensory information is amassed in real-time to form a dynamic model of the system being controlled and its environment. No explicit model is provided a priori, nor any hint about what the structure of the model might be. As the core of a Brain-Emulating Cognition and Control Architecture (BECCA), S-Learning provides a mechanism for human-inspired learning, memory, and control in machines. In a simulation of a point-to-point reaching task, S-Learning demonstrates several attributes of human motor behavior, including learning through exploration and task transfer. © 2007 IEEE.

We present a study of multithreaded implementations of Thorup 's algorithm, for solving the Single Source Shortest Path (SSSP) problem for undirected graphs. Our implementations leverage the fledgling Multithreaded Graph Library (MTGL) to perform operations such as finding connected components and extracting induced subgraphs. To achieve good parallel performance from this algorithm, we deviate from several theoretically optimal algorithmic steps. In this paper, we present simplifications that perform better in practice, and we describe details of the multithreaded implementation that were, necessary for scalability, We study synthetic graphs that model unstructured networks, such as social networks and economic transaction networks. Most of the recent progress in shortest path algorithms relies on structure that these networks do not have. In this work, we take a step back and explore the synergy between an elegant theoretical algorithm and an elegant computer architecture. Finally, we conclude with a prediction that this work will become relevant to shortest path computation on structured networks. ©2007 IEEE.

Observed peptide gas-phase fragmentation patterns are a complex function of many variables. In order to systematically probe this phenomenon, an array of 40 peptides was synthesized for study. The array of sequences was designed to hold certain variables (peptide length) constant and randomize or balance others (peptide amino acid distribution and position). A high-quality tandem mass spectrometry (MS/MS) data set was acquired for each peptide for all observed charge states on multiple MS instruments, quadrupole-time-of-flight and quadrupole ion trap. The data were analyzed as a function of total charge state and number of mobile protons. Previously known dissociation trends were observed, validating our approach. In addition, the general influence of basic amino acids on dissociation could be determined because, in contrast to the more widely studied tryptic peptides, the amino acids H, K, and R were positionally distributed. Interestingly, our results suggest that cleavage at all basic amino acids is suppressed when a mobile proton is available. Cleavage at H becomes favored only under conditions where a partially mobile proton is present, a caveat to the previously reported trend of enhanced cleavage at H. In conclusion, all acquired data were used as a benchmark to determine how well these sequences would have been identified in a database search using a common algorithm, Mascot.

Here, we examine the coupling of the patterned-interface-reconstruction (PIR) algorithm with the extended finite element method (X-FEM) for general multi-material problems over structured and unstructured meshes. The coupled method offers the advantages of allowing for local, element-based reconstructions of the interface, and facilitates the imposition of discrete conservation laws. Of particular note is the use of an interface representation that is volume-of-fluid based, giving rise to a segmented interface representation that is not continuous across element boundaries. In conjunction with such a representation, we employ enrichment with the ridge function for treating material interfaces and an analog to Heaviside enrichment for treating free surfaces. We examine a series of benchmark problems that quantify the convergence aspects of the coupled method and examine the sensitivity to noise in the interface reconstruction. Finally, the fidelity of a remapping strategy is also examined for a moving interface problem.

This paper presents a new algebraic extension of the Rayleigh quotient multigrid (RQMG) minimization algorithm to compute the smallest eigenpairs of a symmetric positive definite pencil (A, M). Earlier versions of RQMG minimize the Rayleigh quotient over a hierarchy of geometric grids. We replace the geometric mesh information with the algebraic information defined by an algebraic multigrid preconditioner. At each level, we minimize the Rayleigh quotient with a block preconditioned algorithm. Numerical experiments illustrate the efficiency of this new algorithm to compute several eigenpairs. Copyright © 2007 John Wiley & Sons, Ltd.

The addition of hydrogen to the natural gas feedstocks of midsize (30-150 MW) gas turbines was analyzed as a method of reducing nitrogen oxides (NOx) and CO2 emissions. In particular, the costs of hydrogen addition were evaluated against the combined costs for other current NOx and CO2 emissions control technologies for both existing and new systems to determine its benefits and market feasibility. Markets for NOx emissions credits currently exist in California and the Northeast States and are expected to grow. Although regulations are not currently in place in the United States, several other countries have implemented carbon tax and carbon credit programs. The analysis thus assumes that the United States adopts future legislation similar to these programs. Therefore, potential sale of emissions credits for volunteer retrofits was also included in the study. It was found that hydrogen addition is a competitive alternative to traditional emissions abatement techniques under certain conditions. The existence of carbon credits shifts the system economics in favor of hydrogen addition. © 2007.

We present a new algorithm for wide-angle propagation through a general class of optical-waveguide structures defined by dielectric interfaces that may be slanted with respect to the direction of propagation. No regularity of the structure shapes is assumed, no coordinate transformations are employed, and the movement of each grid point between propagation steps is arbitrary within modest angular limitations. When used with an appropriate grid-generation algorithm, this method allows the modeling of an extremely wide variety of high-index-contrast waveguide structures, including meanders and tapers, with good phase accuracy and energy conservation. © 2007 IEEE.

This report details the development of a microfabricated preconcentrator that functions as a fully integrated chemical extractor-injector for a microscale gas chromatograph (GC). The device enables parts-per-billion detection and quantitative analysis of volatile organic compounds (VOCs) in indoor air with size and power advantages over macro-scale systems. The 44 mm{sup 3} preconcentrator extracts VOCs using highly adsorptive, granular forms of graphitized carbon black and carbon molecular sieves. The micron-sized silicon cavities have integrated heating and temperature sensing allowing low power, yet rapid heating to thermally desorb the collected VOCs (GC injection). The keys to device construction are a new adsorbent-solvent filling technique and solvent-tolerant wafer-level silicon-gold eutectic bonding technology. The product is the first granular adsorbent preconcentrator integrated at the wafer level. Other advantages include exhaustive VOC extraction and injection peak widths an order of magnitude narrower than predecessor prototypes. A mass transfer model, the first for any microscale preconcentrator, is developed to describe both adsorption and desorption behaviors. The physically intuitive model uses implicit and explicit finite differences to numerically solve the required partial differential equations. The model is applied to the adsorption and desorption of decane at various concentrations to extract Langmuir adsorption isotherm parameters from effluent curve measurements where properties are unknown a priori.

TPI Composites, Inc. (TPI), Global Energy Concepts, LLC (GEC), and MDZ Consulting (MDZ) have collaborated on a project to design, manufacture, and test prototype carbon-fiberglass hybrid wind turbine blades of 9-m length. The project, funded by Sandia National Laboratories, involves prototype blades in both conventional (unidirectional spar fibers running along the blade span) and ''adaptive'' (carbon fibers in off-axis orientation to achieve bend-twist-coupling) configurations. After manufacture, laboratory testing is being conducted to determine the static and fatigue strength of the prototypes, in conjunction with field testing to evaluate the performance under operational conditions.

We report an analysis of four strains of baker's yeast Saccharomyces cerevisiae using biocavity laser spectroscopy. The four strains are grouped in two pairs wild type and altered, in which one strain differs genetically at a single locus, affecting mitochondrial function. In one pair, the wild-type + and a 0 strain differ by complete removal of mitochondrial DNA mtDNA. In the second pair, the wild-type + and a ? strain differ by knock-out of the nuclear gene encoding Cox4, an essential subunit of cytochrome c oxidase. The biocavity laser is used to measure the biophysical optic parameter , a laser wavelength shift relating to the optical density of cell or mitochondria that uniquely reflects its size and biomolecular composition. As such, is a powerful parameter that rapidly interrogates the biomolecular state of single cells and mitochondria. Wild-type cells and mitochondria produce Gaussian-like distributions with a single peak. In contrast, mutant cells and mitochondria produce leptokurtotic distributions that are asymmetric and highly skewed to the right. These distribution changes could be self-consistently modeled with a single, log-normal distribution undergoing a thousand-fold increase in variance of biomolecular composition. These features reflect a new state of stressed or diseased cells that we call a reactive biomolecular divergence RBD that reflects the vital interdependence of mitochondria and the nucleus. © 2007 Society of Photo-Optical Instrumentation Engineers.

Recently published results for a rigid spherical indenter contacting a thin, linear elastic coating on a rigid planar substrate have been extended to include the case of two contacting spheres, where each sphere is rigid and coated with a thin, linear elastic material. This is done by using an appropriately chosen effective radius and coating modulus. The earlier work has also been extended to provide analytical results that span the transition between the previously derived Derjaguin-Müller-Toporov (DMT)-like (work of adhesion/ coating-modulus ratio is small) and Johnson-Kendall-Roberts (JKR)-like (work of adhesion/coating-modulus ratio is large) limits.

An error was discovered in the ALGEBBRA script used to calculate the disturbed rock zone around the disposal room and the shear failure zone in the anhydrite layers in the original version. To correct the error, a memorandum of correction was submitted according to the Waste Isolation Pilot Plant (WIPP) Quality Assurance program. The recommended course of action was to correct the error, to repeat the post-process, and to rewrite Section 7.4, 7.5, 8, and Appendix B in the original report. The sections and appendix revised by the post-process using the corrected ALGEBRA scripts are provided in this revision. The original report summarizes a series of structural calculations that examine effects of raising the WIPP repository horizon from the original design level upward 2.43 meters. Calculations were then repeated for grid changes appropriate for the new horizon raised to Clay Seam G. Results are presented in three main areas: (1) Disposal room porosity, (2) Disturbed rock zone characteristics, and (3) Anhydrite marker bed failure. No change to the porosity surface for the compliance re-certification application is necessary to account for raising the repository horizon, because the new porosity surface is essentially identical. The disturbed rock zone evolution and devolution are charted in terms of a stress invariant criterion over the regulatory period. This model shows that the propagation of the DRZ into the surrounding rock salt does not penetrate through MB 139 in the case of both the original horizon and the raised room. Damaged salt would be expected to heal in nominally 150 years. The shear failure does not occur in either the upper or lower anhydrite layers at the moment of excavation, but appears above and below the middle of the pillar one day after the excavation. The damaged anhydrite is not expected to heal as the salt in the DRZ is expected to.

This document is the final report for the Antarctica Synthetic Aperture Radar (SAR) Project. The project involved the modification of a Sandia National Laboratories MiniSAR system to operate at X-band in order to assess the feasibility of an airborne radar to detect crevasses in Antarctica. This radar successfully detected known crevasses at various geometries. The best results were obtained for synthetic aperture radar resolutions of at most one foot and finer. In addition to the main goal of detecting crevasses, the radar was used to assess conops for a future operational radar. The radar scanned large areas to identify potential safe landing zones. In addition, the radar was used to investigate looking at objects on the surface and below the surface of the ice. This document includes discussion of the hardware development, system capabilities, and results from data collections in Antarctica.

Environmental legislation related to lead-free soldering technology that have been imposed in several nations are requiring manufacturers to consider several technical and business issues to effectively use the lead-free soldering technology. Several researches for reflow/furnace soldering have focused on tin-silver-copper compositions, commonly referred to as the SAC alloys. These alloys exhibit similar processing performance but presents both solderability and temperature sensitivity issues. The SAC396 alloy has been recommended as a standard replacement for tin/lead solders by the International Electronics Manufacturing Initiative. Long-term reliability is also a primary concern associated with the adaptation of lead-free solder alloys for critical applications. The international soldering community is continuously working to meet the technical challenges of implementing a lead-free soldering technology into consumer and high-reliability electronics.

CHARICE is a multi-platform computer application that analyzes velocity waveform data from ramp-wave experiments to determine a material's quasi-isentropic loading response in stress and density using an iterative characteristics-based approach. The application was built using ITT Visual Information Solutions Interactive Data Language (IDL{reg_sign}), and features graphical interfaces for all user interaction. This report describes the calculation method and available analysis options, and gives instructions for using the application.

This document provides an empirically based performance model for grid-connected photovoltaic inverters used for system performance (energy) modeling and for continuous monitoring of inverter performance during system operation. The versatility and accuracy of the model were validated for a variety of both residential and commercial size inverters. Default parameters for the model can be obtained from manufacturers specification sheets, and the accuracy of the model can be further refined using measurements from either well-instrumented field measurements in operational systems or using detailed measurements from a recognized testing laboratory. An initial database of inverter performance parameters was developed based on measurements conducted at Sandia National Laboratories and at laboratories supporting the solar programs of the California Energy Commission.

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An unavoidable by-product of a metallic structure's use is the appearance of crack, corrosion, erosion and other flaws. Economic barriers to the replacement of these structures have created an aging civil and military infrastructure and placed even greater demands on efficient and safe repair and inspection methods. As a result of Homeland Security issues and these aging infrastructure concerns, increased attention has been focused on the rapid repair and preemptive reinforcement of structures such as buildings and bridges. This Laboratory Directed Research and Development (LDRD) program established the viability of using bonded composite patches to repair metallic structures. High modulus fiber-reinforced polymer (FRP) material may be used in lieu of mechanically fastened metallic patches or welds to reinforce or repair damaged structures. Their use produces a wide array of engineering and economic advantages. Current techniques for strengthening steel structures have several drawbacks including requiring heavy equipment for installation, poor fatigue performance, and the need for ongoing maintenance due to continued corrosion attack or crack growth. The use of bonded composite doublers has the potential to correct the difficulties associated with current repair techniques and the ability to be applied where there are currently no rehabilitation options. Applications include such diverse structures as: buildings, bridges, railroad cars, trucks and other heavy machinery, steel power and communication towers, pipelines, factories, mining equipment, ships, tanks and other military vehicles. This LDRD also proved the concept of a living infrastructure by developing custom sensors and self-healing chemistry and linking this technology with the application of advanced composite materials. Structural Health Monitoring (SHM) systems and mountable, miniature sensors were designed to continuously or periodically assess structural integrity. Such systems are able to detect incipient damage before catastrophic failure occurs. The ease of monitoring an entire network of distributed sensors means that structural health assessments can occur more often, allowing operators to be even more vigilant with respect to flaw onset. In addition, the realization of smart structures, through the use of in-situ sensors, allows condition-based maintenance to be substituted for conventional time-based maintenance practices. The sensitivity and reliability of a series of sensor systems was quantified in laboratory and real-world environments. Finally, self healing methods for composite materials were evolved--using resin modules that are released in response to the onset of delaminations--so that these components can provide a living infrastructure with minimal need for human intervention. This program consisted of four related research elements: (1) design, installation, and performance assessment of composite repairs, (2) in-situ sensors for real-time health monitoring, (3) self healing of in-service damage in a repair, and (4) numerical modeling. Deployment of FRP materials and bonded joints requires proper design, suitable surface preparation methods, and adequate surveillance to ensure structural integrity. By encompassing all 'cradle-to-grave' tasks --including design, analysis, installation, durability, flaw containment, and inspection--this program is designed to firmly establish the capabilities of composite doubler repairs and introduce technology to incorporate self-monitoring and self-healing (living structures) methodologies. A proof-of-concept repair was completed on a steel highway bridge in order to demonstrate the potential of composite doubler technology for critical infrastructure use.

This report (Nuclear Power Plant Security Assessment Technical Manual) is a revision to NUREG/CR-1345 (Nuclear Power Plant Design Concepts for Sabotage Protection) that was published in January 1981. It provides conceptual and specific technical guidance for U.S. Nuclear Regulatory Commission nuclear power plant design certification and combined operating license applicants as they: (1) develop the layout of a facility (i.e., how buildings are arranged on the site property and how they are arranged internally) to enhance protection against sabotage and facilitate the use of physical security features; (2) design the physical protection system to be used at the facility; and (3) analyze the effectiveness of the PPS against the design basis threat. It should be used as a technical manual in conjunction with the 'Nuclear Power Plant Security Assessment Format and Content Guide'. The opportunity to optimize physical protection in the design of a nuclear power plant is obtained when an applicant utilizes both documents when performing a security assessment. This document provides a set of best practices that incorporates knowledge gained from more than 30 years of physical protection system design and evaluation activities at Sandia National Laboratories and insights derived from U.S. Nuclear Regulatory Commission technical staff into a manual that describes a development and analysis process of physical protection systems suitable for future nuclear power plants. In addition, selected security system technologies that may be used in a physical protection system are discussed. The scope of this document is limited to the identification of a set of best practices associated with the design and evaluation of physical security at future nuclear power plants in general. As such, it does not provide specific recommendations for the design and evaluation of physical security for any specific reactor design. These best practices should be applicable to the design and evaluation of physical security for all future plants. Note that the original NUREG/CR-1345 remains valid for many light water reactor designs. While the focus of this document is on new plants, existing nuclear power plants and nuclear material facilities may be able to apply these best practices and security system technologies when upgrading or modifying their physical protection systems.

As the power requirements for modern electronics continue to decrease, many devices which were once dependent on wired power are now being implemented as portable devices operating from self-contained power sources. The most prominent source of portable power is the electrochemical battery, which converts chemical energy into electricity. However, long lasting batteries require large amounts of space for chemical storage, and inevitably require replacement when the chemical reaction no longer takes place. There are many transducers and scavenging energy sources (SES) that are able to exploit their environment to generate low levels of electrical power over a long-term time period, including photovoltaic cells, thermoelectric generators, thermionic generators, and kinetic/piezoelectric power generators. This generated power is sustainable as long as specific environmental conditions exist and also does not require the large volume of a long lifetime battery. In addition to the required voltage generation, stable power conversion requires excess energy to be efficiently stored in an ultracapacitor or similar device and monitoring control algorithms to be implemented, while computer modeling and simulation can be used to complement experimental testing. However, building an efficient and stable power source scavenged from a varying input source is challenging.

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Pakistani and Indian militaries have been occupying the Siachen Glacier and surrounding regions for decades. Although a cease-fire is in place, continued occupation carries the risk of an inadvertent conflict, which could escalate into a full-fledged nuclear-backed confrontation. Political and military analysts in Pakistan and India now question the strategic significance of the Siachen Glacier and agree that under the right circumstances, military withdrawal from the Siachen Glacier region would not adversely affect either state. The difficulty lies in conducting the withdrawal in such a way that neither side feels vulnerable, and in maintaining the demilitarization in a way that can be verified. In this paper, the authors who have both held command responsibilities in the Siachen Glacier region present a process for conducting and verifying the demilitarization of the Siachen Glacier region. The authors discuss the role of monitoring and verification tools and their relevance to this border zone of conflict.

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A web-based brainstorm was conducted in the summer of 2007 within the Sandia Restricted Network. This brainstorming experiment was modeled around the 'yellow sticky' brainstorms that are used in many face-to-face meetings at Sandia National Laboratories. This document discusses the implementation and makes suggestions for future implementations.

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This guide describes the R&A process, Common Look and Feel requirements, and preparation and publishing procedures for communication products at Sandia National Laboratories. Samples of forms and examples of published communications products are provided. This guide takes advantage of the wealth of material now available on the Web as a resource. Therefore, it is best viewed as an electronic document. If some of the illustrations are too small to view comfortably, you can enlarge them on the screen as needed. The most significant changes since Version 1 involve the introduction of the electronic Review and Approval application at the Sandia/California (CA) and Sandia/New Mexico (NM) sites. Authors are advised to check the most current material on the application Web site before initiating the R&A process. The format of this document is considerably different than that expected of a SAND Report. It was selected to permit the large number of illustrations and examples to be placed closer to the text that references them. In the case of forms, covers, and other items that are included as examples, a link to the Web is provided so that you can access the items and download them for use.

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Energy demand and GDP per capita are strongly correlated, while public concern over the role of energy in climate change is growing. Nuclear power plants produce 16% of world electricity demands without greenhouse gases. Generation-IV advanced nuclear energy systems are being designed to be safe and economical. Minimizing the handling and storage of nuclear waste is important. NIF and ITER are bringing sustainable fusion energy closer, but a significant gap in fusion technology development remains. Fusion-fission hybrids could be a synergistic step to a pure fusion economy and act as a technology bridge. We discuss how a pulsed power-driven Z-pinch hybrid system producing only 20 MW of fusion yield can drive a sub-critical transuranic blanket that transmutes 1280 kg of actinide wastes per year and produces 3000 MW. These results are applicable to other inertial and magnetic fusion energy systems. A hybrid system could be introduced somewhat sooner because of the modest fusion yield requirements and can provide both a safe alternative to fast reactors for nuclear waste transmutation and a maturation path for fusion technology. The development and demonstration of advanced materials that withstand high-temperature, high-irradiation environments is a fundamental technology issue that is common to both fusion-fission hybrids and Generation-IV reactors.

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The key piece of knowledge necessary for building defenses capable of withstanding or surviving cyber and kinetic attacks is an understanding of the capabilities posed by threats to a government, function, or system. With the number of threats continuing to increase, it is no longer feasible to enumerate the capabilities of all known threats and then build defenses based on those threats that are considered, at the time, to be the most relevant. Exacerbating the problem for critical infrastructure entities is the fact that the majority of detailed threat information for higher-level threats is held in classified status and is not available for general use, such as the design of defenses and the development of mitigation strategies. To reduce the complexity of analyzing threat, the threat space must first be reduced. This is achieved by taking the continuous nature of the threat space and creating an abstraction that allows the entire space to be grouped, based on measurable attributes, into a small number of distinctly different levels. The work documented in this report is an effort to create such an abstraction.

The need to protect national critical infrastructure has led to the development of a threat analysis framework. The threat analysis framework can be used to identify the elements required to quantify threats against critical infrastructure assets and provide a means of distributing actionable threat information to critical infrastructure entities for the protection of infrastructure assets. This document identifies and describes five key elements needed to perform a comprehensive analysis of threat: the identification of an adversary, the development of generic threat profiles, the identification of generic attack paths, the discovery of adversary intent, and the identification of mitigation strategies.

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The need to anticipate the consequences of policy decisions becomes ever more important as the magnitude of the potential consequences grows. The multiplicity of connections between the components of society and the economy makes intuitive assessments extremely unreliable. Agent-based modeling has the potential to be a powerful tool in modeling policy impacts. The direct mapping between agents and elements of society and the economy simplify the mapping of real world functions into the world of computation assessment. Our modeling initiative is motivated by the desire to facilitate informed public debate on alternative policies for how we, as a nation, provide healthcare to our population. We explore the implications of this motivation on the design and implementation of a model. We discuss the choice of an agent-based modeling approach and contrast it to micro-simulation and systems dynamics approaches.

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The use of combined imagery from different imaging sensors has the potential to provide significant performance improvements over the use of a single image sensor for beyond-the-fence detection and assessment of intruders. Sensing beyond the fence is very challenging for imagers due to uncertain dynamic and harsh environmental conditions. The use of imagery from varying spectral bands can alleviate some of this difficulty by providing stronger truth data that can be combined with truth data from other spectral bands to increase detection capabilities. Imagery fusion of collocated, aligned sensors covering varying spectral bands [1,2,3] has already been shown to improve the probability of detection and the reduction of nuisance alarms. The development of new multi-spectral sensing algorithms that incorporate sensors that are not collocated will enable automated sensor-based detection, assessment, localization, and tracking in harsh dynamic environments. This level of image fusion will provide the capability of creating spatial information about the intruders. In turn, the fidelity of sensed activities is increased resulting in opportunities for greater system intelligence for inferring and interpreting these activities and formulating automated responses. The goal of this work is to develop algorithms that will enable the fusion of multi-spectral data for improved detection of intruders and the creation of spatial information that can be further used in assessment decisions.

This report documents the results for the FY07 ASC Integrated Codes Level 2 Milestone number 2354. The description for this milestone is, 'Demonstrate level set free surface tracking capabilities in ARIA to simulate the dynamics of the formation and time evolution of a weld pool in laser welding applications for neutron generator production'. The specialized boundary conditions and material properties for the laser welding application were implemented and verified by comparison with existing, two-dimensional applications. Analyses of stationary spot welds and traveling line welds were performed and the accuracy of the three-dimensional (3D) level set algorithm is assessed by comparison with 3D moving mesh calculations.

Constitutive models for computational solid mechanics codes are in LAME--the Library of Advanced Materials for Engineering. These models describe complex material behavior and are used in our finite deformation solid mechanics codes. To ensure the correct implementation of these models, regression tests have been created for constitutive models in LAME. A selection of these tests is documented here. Constitutive models are an important part of any solid mechanics code. If an analysis code is meant to provide accurate results, the constitutive models that describe the material behavior need to be implemented correctly. Ensuring the correct implementation of constitutive models is the goal of a testing procedure that is used with the Library of Advanced Materials for Engineering (LAME) (see [1] and [2]). A test suite for constitutive models can serve three purposes. First, the test problems provide the constitutive model developer a means to test the model implementation. This is an activity that is always done by any responsible constitutive model developer. Retaining the test problem in a repository where the problem can be run periodically is an excellent means of ensuring that the model continues to behave correctly. A second purpose of a test suite for constitutive models is that it gives application code developers confidence that the constitutive models work correctly. This is extremely important since any analyst that uses an application code for an engineering analysis will associate a constitutive model in LAME with the application code, not LAME. Therefore, ensuring the correct implementation of constitutive models is essential for application code teams. A third purpose of a constitutive model test suite is that it provides analysts with example problems that they can look at to understand the behavior of a specific model. Since the choice of a constitutive model, and the properties that are used in that model, have an enormous effect on the results of an analysis, providing problems that highlight the behavior of various constitutive models to the engineer can be of great benefit. LAME is currently implemented in the Sierra based solid mechanics codes Adagio [3] and Presto [4]. The constitutive models in LAME are available in both codes. Due to the nature of a transient dynamics code--e.g. Presto--it is difficult to test a constitutive model due to inertia effects that show up in the solution. Therefore the testing of constitutive models is primarily done in Adagio. All of the test problems detailed in this report are run in Adagio. It is the goal of the constitutive model test suite to provide a useful service for the constitutive model developer, application code developer and engineer that uses the application code. Due to the conflicting needs and tight time constraints on solid mechanics code development, no requirements exist for implementing test problems for constitutive models. Model developers are strongly encouraged to provide test problems and document those problems, but given the choice of having a model without a test problem or no model at all, certain requirements must be kept loose. A flexible code development environment, especially with regards to research and development in constitutive modeling, is essential to the success of such an environment. This report provides documentation of a number of tests for the constitutive models in LAME. Each section documents a separate test with a brief description of the model, the test problem and the results. This report is meant to be updated periodically as more test problems are created and put into the test suite.

The Library of Advanced Materials for Engineering (LAME) provides a common repository for constitutive models that can be used in computational solid mechanics codes. A number of models including both hypoelastic (rate) and hyperelastic (total strain) constitutive forms have been implemented in LAME. The structure and testing of LAME is described in Scherzinger and Hammerand ([3] and [4]). The purpose of the present report is to describe the material models which have already been implemented into LAME. The descriptions are designed to give useful information to both analysts and code developers. Thus far, 33 non-ITAR/non-CRADA protected material models have been incorporated. These include everything from the simple isotropic linear elastic models to a number of elastic-plastic models for metals to models for honeycomb, foams, potting epoxies and rubber. A complete description of each model is outside the scope of the current report. Rather, the aim here is to delineate the properties, state variables, functions, and methods for each model. However, a brief description of some of the constitutive details is provided for a number of the material models. Where appropriate, the SAND reports available for each model have been cited. Many models have state variable aliases for some or all of their state variables. These alias names can be used for outputting desired quantities. The state variable aliases available for results output have been listed in this report. However, not all models use these aliases. For those models, no state variable names are listed. Nevertheless, the number of state variables employed by each model is always given. Currently, there are four possible functions for a material model. This report lists which of these four methods are employed in each material model. As far as analysts are concerned, this information is included only for the awareness purposes. The analyst can take confidence in the fact that model has been properly implemented and the methods necessary for achieving accurate and efficient solutions have been incorporated. The most important method is the getStress function where the actual material model evaluation takes place. Obviously, all material models incorporate this function. The initialize function is included in most material models. The initialize function is called once at the beginning of an analysis and its primary purpose is to initialize the material state variables associated with the model. Many times, there is some information which can be set once per load step. For instance, we may have temperature dependent material properties in an analysis where temperature is prescribed. Instead of setting those parameters at each iteration in a time step, it is much more efficient to set them once per time step at the beginning of the step. These types of load step initializations are performed in the loadStepInit method. The final function used by many models is the pcElasticModuli method which changes the moduli that are to be used by the elastic preconditioner in Adagio. The moduli for the elastic preconditioner are set during the initialization of Adagio. Sometimes, better convergence can be achieved by changing these moduli for the elastic preconditioner. For instance, it typically helps to modify the preconditioner when the material model has temperature dependent moduli. For many material models, it is not necessary to change the values of the moduli that are set initially in the code. Hence, those models do not have pcElasticModuli functions. All four of these methods receive information from the matParams structure as described by Scherzinger and Hammerand.

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Full coupling of the Calore and Fuego codes has been exercised in this report. This is done to allow solution of general conjugate heat transfer applications that require more than a fluid flow analysis with a very simple conduction region (solved using Fuego alone) or more than a complex conduction/radiation analysis using a simple Newton's law of cooling boundary condition (solved using Calore alone). Code coupling allows for solution of both complex fluid and solid regions, with or without thermal radiation, either participating or non-participating. A coupled physics model is developed to compare to data taken from a horizontal concentric cylinder arrangement using the Penlight heating apparatus located at the thermal test complex (TTC) at Sandia National Laboratories. The experimental set-up requires use of a conjugate heat transfer analysis including conduction, nonparticipating thermal radiation, and internal natural convection. The fluids domain in the model is complex and can be characterized by stagnant fluid regions, laminar circulation, a transition regime, and low-level turbulent regions, all in the same domain. Subsequently, the fluids region requires a refined mesh near the wall so that numerical resolution is achieved. Near the wall, buoyancy exhibits its strongest influence on turbulence (i.e., where turbulence conditions exist). Because low-Reynolds number effects are important in anisotropic natural convective flows of this type, the {ovr {nu}{sup 2}}-f turbulence model in Fuego is selected and compared to results of laminar flow only. Coupled code predictions are compared to temperature measurements made both in the solid regions and a fluid region. Turbulent and laminar flow predictions are nearly identical for both regions. Predicted temperatures in the solid regions compare well to data. The largest discrepancies occur at the bottom of the annulus. Predicted temperatures in the fluid region, for the most part, compare well to data. As before, the largest discrepancies occur at the bottom of the annulus where the flow transitions to or is a low-level turbulent flow.

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There is a need in security systems to rapidly and accurately grant access of authorized personnel to a secure facility while denying access to unauthorized personnel. In many cases this role is filled by security personnel, which can be very costly. Systems that can perform this role autonomously without sacrificing accuracy or speed of throughput are very appealing. To address the issue of autonomous facility access through the use of technology, the idea of a ''secure portal'' is introduced. A secure portal is a defined zone where state-of-the-art technology can be implemented to grant secure area access or to allow special privileges for an individual. Biometric technologies are of interest because they are generally more difficult to defeat than technologies such as badge swipe and keypad entry. The biometric technologies selected for this concept were facial and gait recognition. They were chosen since they require less user cooperation than other biometrics such as fingerprint, iris, and hand geometry and because they have the most potential for flexibility in deployment. The secure portal concept could be implemented within the boundaries of an entry area to a facility. As a person is approaching a badge and/or PIN portal, face and gait information can be gathered and processed. The biometric information could be fused for verification against the information that is gathered from the badge. This paper discusses a facial recognition technology that was developed for the purposes of providing high verification probabilities with low false alarm rates, which would be required of an autonomous entry control system. In particular, a 3-D facial recognition approach using Fisher Linear Discriminant Analysis is described. Gait recognition technology, based on Hidden Markov Models has been explored, but those results are not included in this paper. Fusion approaches for combining the results of the biometrics would be the next step in realizing the secure portal concept.

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The sintering behavior of Sandia chem-prep high field varistor materials was studied using techniques including in situ shrinkage measurements, optical and scanning electron microscopy and x-ray diffraction. A thorough literature review of phase behavior, sintering and microstructure in Bi{sub 2}O{sub 3}-ZnO varistor systems is included. The effects of Bi{sub 2}O{sub 3} content (from 0.25 to 0.56 mol%) and of sodium doping level (0 to 600 ppm) on the isothermal densification kinetics was determined between 650 and 825 C. At {ge} 750 C samples with {ge}0.41 mol% Bi{sub 2}O{sub 3} have very similar densification kinetics, whereas samples with {le}0.33 mol% begin to densify only after a period of hours at low temperatures. The effect of the sodium content was greatest at {approx}700 C for standard 0.56 mol% Bi{sub 2}O{sub 3} and was greater in samples with 0.30 mol% Bi{sub 2}O{sub 3} than for those with 0.56 mol%. Sintering experiments on samples of differing size and shape found that densification decreases and mass loss increases with increasing surface area to volume ratio. However, these two effects have different causes: the enhancement in densification as samples increase in size appears to be caused by a low oxygen internal atmosphere that develops whereas the mass loss is due to the evaporation of bismuth oxide. In situ XRD experiments showed that the bismuth is initially present as an oxycarbonate that transforms to metastable {beta}-Bi{sub 2}O{sub 3} by 400 C. At {approx}650 C, coincident with the onset of densification, the cubic binary phase, Bi{sub 38}ZnO{sub 58} forms and remains stable to >800 C, indicating that a eutectic liquid does not form during normal varistor sintering ({approx}730 C). Finally, the formation and morphology of bismuth oxide phase regions that form on the varistors surfaces during slow cooling were studied.

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A new rotary MEMS actuator has been developed and tested at Sandia National Laboratories that utilizes a linear thermal actuator as the drive mechanism. This actuator was designed to be a low-voltage, high-force alternative to the existing electrostatic torsional ratcheting actuator (TRA) [1]. The new actuator, called the Thermal Rotary Actuator (ThRA), is conceptually much simpler than the TRA and consists of a gear on a hub that is turned by a linear thermal actuator [2] positioned outside of the gear. As seen in Figure 1, the gear is turned through a ratcheting pawl, with anti-reverse pawls positioned around the gear for unidirectional motion (see Figure 1). A primary consideration in the design of the ThRA was the device reliability and in particular, the required one-to-one relationship between the ratcheting output motion and the electrical input signal. The electrostatic TRA design has been shown to both over-drive and under-drive relative to the number of input pulses [3]. Two different ThRA designs were cycle tested to measure the skip rate. This was done in an automated test setup by using pattern matching to measure the angle of rotation of the output gear after a defined number of actuation pulses. By measuring this gear angle over time, the number of skips can be determined. Figure 2 shows a picture of the ThRA during testing, with the pattern-matching features highlighted. In the first design tested, it was found that creep in the thermal actuator limited the number of skip-free cycles, as the rest position of the actuator would creep forward enough to prevent the counter-rotation pawls from fully engaging (Figure 3). Even with this limitation, devices were measured with up to 100 million cycles with no skipping. A design modification was made to reduce the operating temperature of the thermal actuator which has been shown in a previous study [2] to reduce the creep rate. In addition, changes were made to the drive ratchet design and actuation direction to increase the available output force. This new design was tested and shown to operate in one case out to greater than 360 million cycles without any skipping, after which the test was stopped without failure. The output force was also measured as a function of input voltage (Figure 4), and shown to be higher than the previous design. The maximum force shown in the figure is a limit of the gauge used, not the actuator itself. Continued work for this design will focus on understanding the actuator performance while driving a load, as all current tests were performed with no load on the output gear.

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A recent report on criticality accidents in nuclear facilities indicates that human error played a major role in a significant number of incidents with serious consequences and that some of these human errors may be related to the emotional state of the individual. A pre-shift test to detect a deleterious emotional state could reduce the occurrence of such errors in critical operations. The effectiveness of pre-shift testing is a challenge because of the need to gather predictive data in a relatively short test period and the potential occurrence of learning effects due to a requirement for frequent testing. This report reviews the different types of reliability and validity methods and testing and statistical analysis procedures to validate measures of emotional state. The ultimate value of a validation study depends upon the percentage of human errors in critical operations that are due to the emotional state of the individual. A review of the literature to identify the most promising predictors of emotional state for this application is highly recommended.

The present paper explores group dynamics and electronic communication, two components of wicked problem solving that are inherent to the national security environment (as well as many other business environments). First, because there can be no ''right'' answer or solution without first having agreement about the definition of the problem and the social meaning of a ''right solution'', these problems (often) fundamentally relate to the social aspects of groups, an area with much empirical research and application still needed. Second, as computer networks have been increasingly used to conduct business with decreased costs, increased information accessibility, and rapid document, database, and message exchange, electronic communication enables a new form of problem solving group that has yet to be well understood, especially as it relates to solving wicked problems.

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This report summarizes the major research and development accomplishments for the late start LDRD project (investment area: Enable Predictive Simulation) entitled 'Atomically Engineering Cu/Ta Interfaces'. Two ultimate goals of the project are: (a) use atomistic simulation to explore important atomistic assembly mechanisms during growth of Cu/Ta multilayers; and (b) develop a non-continuum model that has sufficient fidelity and computational efficiency for use as a design tool. Chapters 2 and 3 are essentially two papers that address respectively these two goals. In chapter 2, molecular dynamics simulations were used to study the growth of Cu films on (010) bcc Ta and Cu{sub x}Ta{sub 1-x} alloy films on (111) fcc Cu. The results indicated that fcc crystalline Cu films with a (111) texture are always formed when Cu is grown on Ta. The Cu films are always polycrystalline even when the Ta substrate is single crystalline. These polycrystalline films are composed of grains with only two different orientations, which are separated by either orientational grain boundaries or misfit dislocations. Periodic misfit dislocations and stacking fault bands are observed. The Cu film surface roughness was found to decrease with increasing adatom energy. Due to a Cu surface segregation effect, the Cu{sub x}Ta{sub 1-x} films deposited on Cu always have a higher Cu composition than that used in the vapor mixture. When Cu and Ta compositions in the films are comparable, amorphous structures may form. The fundamental origins for all these phenomena have been studied in terms of crystallography and interatomic interactions. In chapter 3, a simplified computational method, diffusional Monte Carlo (dMC) method, was developed to address long time kinetic processes of materials. Long time kinetic processes usually involve material transport by diffusion. The corresponding microstructural evolution of materials can be analyzed by kinetic Monte Carlo simulation methods, which essentially simulate structural evolution by tracing each atomic jump. However, if the simulation is carried out at a high temperature, or a jump mechanism with a very low energy barrier is encountered, the jump frequency may approach the atom vibration frequency, and the computational efficiency of the kinetic Monte Carlo method rapidly decreases to that of a molecular dynamics simulation. The diffusional Monte Carlo method addresses the net effects of many atom jumps over a finite duration, kinetically controlled process. First, atom migration due to both random and non-random jumps is discussed. The concept of dMC is then introduced for random jump diffusion. The validity of the method is demonstrated using several diffusion cases in one-, two- and three-dimensional spaces, including the dissolution of spinodal structures. The application of the non-random diffusion theory to spinodal decomposition is also demonstrated.

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An experiment is proposed which will compare the effectiveness of individual versus group brainstorming in addressing difficult, real world challenges. Previous research into electronic brainstorming has largely been limited to laboratory experiments using small groups of students answering questions irrelevant to an industrial setting. The proposed experiment attempts to extend current findings to real-world employees and organization-relevant challenges. Our employees will brainstorm ideas over the course of several days, echoing the real-world scenario in an industrial setting. The methodology and hypotheses to be tested are presented along with two questions for the experimental brainstorming sessions. One question has been used in prior work and will allow calibration of the new results with existing work. The second question qualifies as a complicated, perhaps even wickedly hard, question, with relevance to modern management practices.

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