Several groups of plastic molded CD4011 were electrically tested as part of an Army dormant storage program. For this test, parts had been in storage in missile containers for 4.5 years. Eight of the parts (out of 1200) failed the electrical tests and were subsequently analyzed to determine the cause of the failures. The root cause was found to be corrosion of the unpassivated Al bondpads. No significant attack of the passivated Al traces was found. Seven of the eight failures occurred in parts stored on a preposition ship (Jeb Stuart), suggesting a link between the external environment and observed corrosion.
Laser scanning confocal microscopy has been applied to study segregation in multi-component wetting. By labeling the two components of a blend with contrasting fluorescent dyes, the approximate local concentration can be determined from the relative fluorescence intensities. As a proof of concept, a coarsely blended mixture was imaged and parameters were adjusted to achieve good spectral separation of the two components. The technique was then applied to a well-blended drop of the two components and one component was observed to segregate to the air interface.
Social and ecological scientists emphasize that effective natural resource management depends in part on understanding the dynamic relationship between the physical and non-physical process associated with resource consumption. In this case, the physical processes include hydrological, climatological and ecological dynamics, and the non-physical process include social, economic and cultural dynamics among humans who do the resource consumption. This project represents a case study aimed at modeling coupled social and physical processes in a single decision support system. In central New Mexico, individual land use decisions over the past five decades have resulted in the gradual transformation of the Middle Rio Grande Valley from a primarily rural agricultural landscape to a largely urban one. In the arid southwestern U.S., the aggregate impact of individual decisions about land use is uniquely important to understand, because scarce hydrological resources will likely limit the viability of resulting growth and development trajectories. This decision support tool is intended to help planners in the area look forward in their efforts to create a collectively defined 'desired' social landscape in the Middle Rio Grande. Our research question explored the ways in which socio-cultural values impact decisions regarding that landscape and associated land use. Because of the constraints hydrological resources place on land use, we first assumed that water use, as embodied in water rights, was a reasonable surrogate for land use. We thought that modeling the movement of water rights over time and across water source types (surface and ground) would provide planners with insight into the possibilities for certain types of decisions regarding social landscapes, and the impact those same decisions would have on those landscapes. We found that water rights transfer data in New Mexico is too incomplete and inaccurate to use as the basis for the model. Furthermore, because of its lack of accuracy and completeness, water rights ownership was a poor indicator of water and land usage habits and patterns. We also found that commitment among users in the Middle Rio Grande Valley is to an agricultural lifestyle, not to a community or place. This commitment is conditioned primarily by generational cohort and past experience. If conditions warrant, many would be willing to practice the lifestyle elsewhere. A related finding was that sometimes the pressure to sell was not the putative price of the land, but the taxes on the land. These taxes were, in turn, a function of the level of urbanization of the neighborhood. This urbanization impacted the quality of the agricultural lifestyle. The project also yielded some valuable lessons regarding the model development process. A facilitative and collaborative style (rather than a top-down, directive style) was most productive with the inter-disciplinary , inter-institutional team that worked on the project. This allowed for the emergence of a process model which combined small, discipline- and/or task-specific subgroups with larger, integrating team meetings. The project objective was to develop a model that could be used to run test scenarios in which we explored the potential impact of different policy options. We achieved that objective, although not with the level of success or modeling fidelity which we had hoped for. This report only describes very superficially the results of test scenarios, since more complete analysis of scenarios would require more time and effort. Our greatest obstacle in the successful completion of the project was that required data were sparse, of poor quality, or completely nonexistent. Moreover, we found no similar modeling or research efforts taking place at either the state or local level. This leads to a key finding of this project: that state and local policy decisions regarding land use, development, urbanization, and water resource allocation are being made with minimal data and without the benefit of economic or social policy analysis.
Warm dense matter is the region in phase space of density and temperature where the thermal, Fermi, and Coulomb energies are approximately equal. The lack of a dominating scale and physical behavior makes it challenging to model the physics to high fidelity. For Sandia, a fundamental understanding of the region is of importance because of the needs of our experimental HEDP programs for high fidelity descriptive and predictive modeling. We show that multi-scale simulations of macroscopic physical phenomena now have predictive capability also for difficult but ubiquitous materials such as stainless steel, a transition metal alloy.
Imagine free-standing flexible membranes with highly-aligned arrays of carbon nanotubes (CNTs) running through their thickness. Perhaps with both ends of the CNTs open for highly controlled nanofiltration? Or CNTs at heights uniformly above a polymer membrane for a flexible array of nanoelectrodes or field-emitters? How about CNT films with incredible amounts of accessible surface area for analyte adsorption? These self-assembled crystalline nanotubes consist of multiple layers of graphene sheets rolled into concentric cylinders. Tube diameters (3-300 nm), inner-bore diameters (2-15 nm), and lengths (nanometers - microns) are controlled to tailor physical, mechanical, and chemical properties. We proposed to explore growth and characterize nanotube arrays to help determine their exciting functionality for Sandia applications. Thermal chemical vapor deposition growth in a furnace nucleates from a metal catalyst. Ordered arrays grow using templates from self-assembled hexagonal arrays of nanopores in anodized-aluminum oxide. Polymeric-binders can mechanically hold the CNTs in place for polishing, lift-off, and membrane formation. The stiffness, electrical and thermal conductivities of CNTs make them ideally suited for a wide-variety of possible applications. Large-area, highly-accessible gas-adsorbing carbon surfaces, superb cold-cathode field-emission, and unique nanoscale geometries can lead to advanced microsensors using analyte adsorption, arrays of functionalized nanoelectrodes for enhanced electrochemical detection of biological/explosive compounds, or mass-ionizers for gas-phase detection. Materials studies involving membrane formation may lead to exciting breakthroughs in nanofiltration/nanochromatography for the separation of chemical and biological agents. With controlled nanofilter sizes, ultrafiltration will be viable to separate and preconcentrate viruses and many strains of bacteria for 'down-stream' analysis.
Chemical microsensors rely on partitioning of airborne chemicals into films to collect and measure trace quantities of hazardous vapors. Polymer sensor coatings used today are typically slow to respond and difficult to apply reproducibly. The objective of this project was to produce a durable sensor coating material based on graphitic nanoporous-carbon (NPC), a new material first studied at Sandia, for collection and detection of volatile organic compounds (VOC), toxic industrial chemicals (TIC), chemical warfare agents (CWA) and nuclear processing precursors (NPP). Preliminary studies using NPC films on exploratory surface-acoustic-wave (SAW) devices and as a {micro}ChemLab membrane preconcentrator suggested that NPC may outperform existing, irreproducible coatings for SAW sensor and {micro}ChemLab preconcentrator applications. Success of this project will provide a strategic advantage to the development of a robust, manufacturable, highly-sensitive chemical microsensor for public health, industrial, and national security needs. We use pulsed-laser deposition to grow NPC films at room-temperature with negligible residual stress, and hence, can be deposited onto nearly any substrate material to any thickness. Controlled deposition yields reproducible NPC density, morphology, and porosity, without any discernable variation in surface chemistry. NPC coatings > 20 {micro}m thick with density < 5% that of graphite have been demonstrated. NPC can be 'doped' with nearly any metal during growth to provide further enhancements in analyte detection and selectivity. Optimized NPC-coated SAW devices were compared directly to commonly-used polymer coated SAWs for sensitivity to a variety of VOC, TIC, CWA and NPP. In every analyte, NPC outperforms each polymer coating by multiple orders-of-magnitude in detection sensitivity, with improvements ranging from 103 to 108 times greater detection sensitivity! NPC-coated SAW sensors appear capable of detecting most analytes tested to concentrations below parts-per-billion. In addition, the graphitic nature of NPC enables thermal stability > 600 C, several hundred degrees higher than the polymers. This superior thermal stability will enable higher-Temperature preconcentrator operation, as well as greatly prolonged device reliability, since polymers tend to degrade with time and repeated thermal cycling.
The convergence of nanoscience and biotechnology has opened the door to the integration of a wide range of biological molecules and processes with synthetic materials and devices. A primary biomolecule of interest has been DNA based upon its role as information storage in living systems, as well as its ability to withstand a wide range of environmental conditions. DNA also offers unique chemistries and interacts with a range of biomolecules, making it an ideal component in biological sensor applications. The primary goal of this project was to develop methods that utilize in vitro DNA synthesis to provide spatial localization of nanocrystal quantum dots (nQDs). To accomplish this goal, three specific technical objectives were addressed: (1) attachment of nQDs to DNA nucleotides, (2) demonstrating the synthesis of nQD-DNA strands in bulk solution, and (3) optimizing the ratio of unlabeled to nQD-labeled nucleotides. DNA nucleotides were successfully attached to nQDs using the biotin-streptavidin linkage. Synthesis of 450-nm long, nQD-coated DNA strands was demonstrated using a DNA template and the polymerase chain reaction (PCR)-based method of DNA amplification. Modifications in the synthesis process and conditions were subsequently used to synthesize 2-{micro}m long linear nQD-DNA assemblies. In the case of the 2-{micro}m structures, both the ratio of streptavidin-coated nQDs to biotinylated dCTP, and streptavidin-coated nQD-dCTPs to unlabeled dCTPs affected the ability to synthesize the nQD-DNA assemblies. Overall, these proof-of-principles experiments demonstrated the successful synthesis of nQD-DNA using DNA templates and in vitro replication technologies. Continued development of this technology may enable rapid, spatial patterning of semiconductor nanoparticles with Angstrom-level resolution, as well as optically active probes for DNA and other biomolecular analyses.
A combined experimental/modeling study was conducted to better understand the critical role of gas-surface interactions in rarefied gas flows. An experimental chamber and supporting diagnostics were designed and assembled to allow simultaneous measurements of gas heat flux and inter-plate gas density profiles in an axisymmetric, parallel-plate geometry. Measurements of gas density profiles and heat flux are made under identical conditions, eliminating an important limitation of earlier studies. The use of in situ, electron-beam fluorescence is demonstrated as a means to measure gas density profiles although additional work is required to improve the accuracy of this technique. Heat flux is inferred from temperature-drop measurements using precision thermistors. The system can be operated with a variety of gases (monatomic, diatomic, polyatomic, mixtures) and carefully controlled, well-characterized surfaces of different types (metals, ceramics) and conditions (smooth, rough). The measurements reported here are for 304 stainless steel plates with a standard machined surface coupled with argon, helium, and nitrogen. The resulting heat-flux and gas-density-profile data are analyzed using analytic and computational models to show that a simple Maxwell gas-surface interaction model is adequate to represent all of the observations. Based on this analysis, thermal accommodation coefficients for 304 stainless steel coupled with argon, nitrogen, and helium are determined to be 0.88, 0.80, and 0.38, respectively, with an estimated uncertainty of {+-}0.02.
Time domain reflectometry (TDR) operates by propagating a radar frequency electromagnetic pulse down a transmission line while monitoring the reflected signal. As the electromagnetic pulse propagates along the transmission line, it is subject to impedance by the dielectric properties of the media along the transmission line (e.g., air, water, sediment), reflection at dielectric discontinuities (e.g., air-water or water-sediment interface), and attenuation by electrically conductive materials (e.g., salts, clays). Taken together, these characteristics provide a basis for integrated stream monitoring; specifically, concurrent measurement of stream stage, channel profile and aqueous conductivity. Here, we make novel application of TDR within the context of stream monitoring. Efforts toward this goal followed three critical phases. First, a means of extracting the desired stream parameters from measured TDR traces was required. Analysis was complicated by the fact that interface location and aqueous conductivity vary concurrently and multiple interfaces may be present at any time. For this reason a physically based multisection model employing the S11 scatter function and Cole-Cole parameters for dielectric dispersion and loss was developed to analyze acquired TDR traces. Second, we explored the capability of this multisection modeling approach for interpreting TDR data acquired from complex environments, such as encountered in stream monitoring. A series of laboratory tank experiments were performed in which the depth of water, depth of sediment, and conductivity were varied systematically. Comparisons between modeled and independently measured data indicate that TDR measurements can be made with an accuracy of {+-}3.4x10{sup -3} m for sensing the location of an air/water or water/sediment interface and {+-}7.4% of actual for the aqueous conductivity. Third, monitoring stations were sited on the Rio Grande and Paria rivers to evaluate performance of the TDR system under normal field conditions. At the Rio Grande site (near Central Bridge in Albuquerque, New Mexico) continuous monitoring of stream stage and aqueous conductivity was performed for 6 months. Additionally, channel profile measurements were acquired at 7 locations across the river. At the Paria site (near Lee's Ferry, Arizona) stream stage and aqueous conductivity data were collected over a 4-month period. Comparisons drawn between our TDR measurements and USGS gage data indicate that the stream stage is accurate within {+-}0.88 cm, conductivity is accurate within {+-}11% of actual, and channel profile measurements agree within {+-}1.2 cm.
Despite continuing efforts to apply existing hazard analysis methods and comply with requirements, human errors persist across the nuclear weapons complex. Due to a number of factors, current retroactive and proactive methods to understand and minimize human error are highly subjective, inconsistent in numerous dimensions, and are cumbersome to characterize as thorough. An alternative and proposed method begins with leveraging historical data to understand what the systemic issues are and where resources need to be brought to bear proactively to minimize the risk of future occurrences. An illustrative analysis was performed using existing incident databases specific to Pantex weapons operations indicating systemic issues associated with operating procedures that undergo notably less development rigor relative to other task elements such as tooling and process flow. Future recommended steps to improve the objectivity, consistency, and thoroughness of hazard analysis and mitigation were delineated.
Deep X-ray lithography on PMMA resist is used in the LIGA process. The resist is exposed to synchrotron X-rays through a patterned mask and then is developed in a liquid developer to make high aspect ratio microstructures. The limitations in dimensional accuracies of the LIGA generated microstructure originate from many sources, including synchrotron and X-ray physics, thermal and mechanical properties of mask and resist, and from the kinetics of the developer. This work addresses the thermal analysis and temperature rise of the mask-resist assembly during exposure in air at the Advanced Light Source (ALS) synchrotron. The concern is that dimensional errors generated at the mask and the resist due to thermal expansion will lower the accuracy of the lithography. We have developed a three-dimensional finite-element model of the mask and resist assembly that includes a mask with absorber, a resist with substrate, three metal holders, and a water-cooling block. We employed the LIGA exposure-development software LEX-D to calculate volumetric heat sources generated in the assembly by X-ray absorption and the commercial software ABAQUS to calculate heat transfer including thermal conduction inside the assembly, natural and forced convection, and thermal radiation. at assembly outer and/or inner surfaces. The calculations of assembly maximum temperature. have been compared with temperature measurements conducted at ALS. In some of these experiments, additional cooling of the assembly was produced by forced nitrogen flow ('nitrogen jets') directed at the mask surface. The temperature rise in the silicon mask and the mask holder comes directly from the X-ray absorption, but nitrogen jets carry away a significant portion of heat energy from the mask surface, while natural convection carries away negligibly small amounts energy from the holder. The temperature rise in PMMA resist is mainly from heat conducted from the silicon substrate backward to the resist and from the inner cavity air forward to the resist, while the X-ray absorption is only secondary. Therefore, reduction of heat flow conducted from both substrate and cavity air to the resist is essential. An improved water-cooling block is expected to carry away most heat energy along the main heat conductive path, leaving the resist at a favorable working temperature.
Acts of terrorism could have a range of broad impacts on an economy, including changes in consumer (or demand) confidence and the ability of productive sectors to respond to changes. As a first step toward a model of terrorism-based impacts, we develop here a model of production and employment that characterizes dynamics in ways useful toward understanding how terrorism-based shocks could propagate through the economy; subsequent models will introduce the role of savings and investment into the economy. We use Aspen, a powerful economic modeling tool developed at Sandia, to demonstrate for validation purposes that a single-firm economy converges to the known monopoly equilibrium price, output, and employment levels, while multiple-firm economies converge toward the competitive equilibria typified by lower prices and higher output and employment. However, we find that competition also leads to churn by consumers seeking lower prices, making it difficult for firms to optimize with respect to wages, prices, and employment levels. Thus, competitive firms generate market ''noise'' in the steady state as they search for prices and employment levels that will maximize profits. In the context of this model, not only could terrorism depress overall consumer confidence and economic activity but terrorist acts could also cause normal short-run dynamics to be misinterpreted by consumers as a faltering economy.
The overall purpose of this LDRD is multifold. First, we are interested in preparing new homogeneous catalysts that can be used in the oligomerization of ethylene and in understanding commercially important systems better. Second, we are interested in attempting to support these new homogeneous catalysts in the pores of nano- or mesoporous materials in order to force new and unusual distributions of a-olefins to be formed during the oligomerization. Thus the overall purpose is to try to prepare new catalytic species and to possibly control the active site architecture in order to yield certain desired products during a catalytic reaction, much like nature does with enzymes. In order to rationally synthesize catalysts it is imperative to comprehend the function of the various components of the catalyst. In heterogeneous systems, it is of utmost importance to know how a support interacts with the active site of the catalyst. In fact, in the catalysis world this lack of fundamental understanding of the relationship between active site and support is the single largest reason catalysis is considered an 'empirical' or 'black box' science rather than a well-understood one. In this work we will be preparing novel ethylene oligomerization catalysts, which are normally P-O chelated homogeneous complexes, with new ligands that replace P with a stable carbene. We will also examine a commercially catalyst system and investigate the active site in it via X-ray crystallography. We will also attempt to support these materials inside the pores of nano- and mesoporous materials. Essentially, we will be tailoring the size and scale of the catalyst active site and its surrounding environment to match the size of the molecular product(s) we wish to make. The overall purpose of the study will be to prepare new homogeneous catalysts, and if successful in supporting them to examine the effects that steric constraints and pore structures can have on growing oligomer chains.
Lien, Steve J.; Baxter, Larry L.; Frederick Jr., W.J.; Wessel, Richard A.
As part of the U.S. Department of Energy (DOE) Office of Industrial Technologies (OIT) Industries of the Future (IOF) Forest Products research program, the mechanisms of particle deposition and properties of deposits that form in the convection passes of recovery boilers were investigated. Research from experimental facilities at Sandia National Laboratories, the Institute of Paper Science and Technology (IPST), and the University of Toronto (U of T) was coordinated into a single effort to define the controlling mechanisms and rates of deposition. Deposition rates were recorded on a volumetric and mass basis in a Sandia facility for particle sizes in the range of 0.1 to 150 {micro}m. Deposit thickness, mass, spectral emissivity, thermal conductivity, surface temperature, and apparent density were monitored simultaneously and in situ on instrumented probes that allow determination of heat flux and probe surface temperature. Particle composition and mass deposition rates were also recorded in a U of T facility for particle sizes in the range of 100 to 600 {micro}m. These measurements allowed determination of the liquid content and sticking efficiency of carryover particles that inertially impact on a deposition probe. In addition, information on particulates, stable gas species, gas temperature and velocity were obtained from field tests in an operating recovery boiler. The results were used to develop algorithms appropriate for use in computer codes that simulate recovery boilers. Representative calculations were performed using B&W's comprehensive recovery boiler model to demonstrate the use of the algorithms in such computer codes. Comparisons between observations in commercial systems and model predictions were made to identify algorithm strengths and weaknesses.
Property-based testing is a testing technique that evaluates executions of a program. The method checks that specifications, called properties, hold throughout the execution of the program. TASpec is a language used to specify these properties. This paper compares some attributes of the language with the specification patterns used for model-checking languages, and then presents some descriptions of properties that can be used to detect common security flaws in programs. This report describes the results of a one year research project at the University of California, Davis, which was funded by a University Collaboration LDRD entitled ''Property-based Testing for Cyber Security Assurance''.
The Matrixed Business Support Comparison Study reviewed the current matrixed Chief Financial Officer (CFO) division staff models at Sandia National Laboratories. There were two primary drivers of this analysis: (1) the increasing number of financial staff matrixed to mission customers and (2) the desire to further understand the matrix process and the opportunities and challenges it creates.
At Sandia National Laboratories, miniaturization dominates future hardware designs, and technologies that address the manufacture of micro-scale to nano-scale features are in demand. Currently, Sandia is developing technologies such as photolithography/etching (e.g. silicon MEMS), LIGA, micro-electro-discharge machining (micro-EDM), and focused ion beam (FIB) machining to fulfill some of the component design requirements. Some processes are more encompassing than others, but each process has its niche, where all performance characteristics cannot be met by one technology. For example, micro-EDM creates highly accurate micro-scale features but the choice of materials is limited to conductive materials. With silicon-based MEMS technology, highly accurate nano-scale integrated devices are fabricated but the mechanical performance may not meet the requirements. Femtosecond laser processing has the potential to fulfill a broad range of design demands, both in terms of feature resolution and material choices, thereby improving fabrication of micro-components. One of the unique features of femtosecond lasers is the ability to ablate nearly all materials with little heat transfer, and therefore melting or damage, to the surrounding material, resulting in highly accurate micro-scale features. Another unique aspect to femtosecond radiation is the ability to create localized structural changes thought nonlinear absorption processes. By scanning the focal point within transparent material, we can create three-dimensional waveguides for biological sensors and optical components. In this report, we utilized the special characteristics of femtosecond laser processing for microfabrication. Special emphasis was placed on the laser-material interactions to gain a science-based understanding of the process and to determine the process parameter space for laser processing of metals and glasses. Two areas were investigated, including laser ablation of ferrous alloys and direct-write optical waveguides and integrated optics in bulk glass. The effects of laser and environmental parameters on such aspects as removal rate, feature size, feature definition, and ablation angle during the ablation process of metals were studied. In addition, the manufacturing requirements for component fabrication including precision and reproducibility were investigated. The effect of laser processing conditions on the optical properties of direct-written waveguides and an unusual laser-induced birefringence in an optically isotropic glass are reported. Several integrated optical devices, including a Y coupler, directional coupler, and Mach-Zehnder interferometer, were made to demonstrate the simplicity and flexibility of this technique in comparison to the conventional waveguide fabrication processes.
We have studied the feasibility of using the 3D fully electromagnetic implicit hybrid particle code LSP (Large Scale Plasma) to study laser plasma interactions with dense, compressed plasmas like those created with Z, and which might be created with the planned ZR. We have determined that with the proper additional physics and numerical algorithms developed during the LDRD period, LSP was transformed into a unique platform for studying such interactions. Its uniqueness stems from its ability to consider realistic compressed densities and low initial target temperatures (if required), an ability that conventional PIC codes do not possess. Through several test cases, validations, and applications to next generation machines described in this report, we have established the suitability of the code to look at fast ignition issues for ZR, as well as other high-density laser plasma interaction problems relevant to the HEDP program at Sandia (e.g. backlighting).
A theory is presented which couples a dynamical laser model to a fully microscopic calculation of scattering effects. Calculations for two optically pumped GaInNAs laser structures show how this approach can be used to analyze nonequilibrium and dynamical laser properties over a wide range of system parameters.
A variety of solution deposition routes have been reported for processing complex perovskite-based materials such as ferroelectric oxides and conductive electrode oxides, due to ease of incorporating multiple elements, control of chemical stoichiometry, and feasibility for large area deposition. Here, we report an extension of these methods toward long length, epitaxial film solution deposition routes to enable biaxially oriented YBa{sub 2}Cu{sub 3}O{sub 7-{delta}} (YBCO)-coated conductors for superconducting transmission wires. Recent results are presented detailing an all-solution deposition approach to YBCO-coated conductors with critical current densities J{sub c} (77 K) > 1 MA/cm{sup 2} on rolling-assisted, biaxially textured, (200)-oriented Ni-W alloy tapes. Solution-deposition methods such as this approach and those of other research groups appear to have promise to compete with vapor phase methods for superconductor electrical properties, with potential advantages for large area deposition and low cost/kA {center_dot} m of wire.
The combination of phase diversity and adaptive optics offers great flexibility. Phase diverse images can be used to diagnose aberrations and then provide feedback control to the optics to correct the aberrations. Alternatively, phase diversity can be used to partially compensate for aberrations during post-detection image processing. The adaptive optic can produce simple defocus or more complex types of phase diversity. This report presents an analysis, based on numerical simulations, of the efficiency of different modes of phase diversity with respect to compensating for specific aberrations during post-processing. It also comments on the efficiency of post-processing versus direct aberration correction. The construction of a bench top optical system that uses a membrane mirror as an active optic is described. The results of characterization tests performed on the bench top optical system are presented. The work described in this report was conducted to explore the use of adaptive optics and phase diversity imaging for responsive space applications.
Sandia National Laboratories was tasked with developing the Defense Nuclear Material Stewardship Integrated Inventory Information Management System (IIIMS) with the sponsorship of NA-125.3 and the concurrence of DOE/NNSA field and area offices. The purpose of IIIMS was to modernize nuclear materials management information systems at the enterprise level. Projects over the course of several years attempted to spearhead this modernization. The scope of IIIMS was broken into broad enterprise-oriented materials management and materials forecasting. The IIIMS prototype was developed to allow multiple participating user groups to explore nuclear material requirements and needs in detail. The purpose of material forecasting was to determine nuclear material availability over a 10 to 15 year period in light of the dynamic nature of nuclear materials management. Formal DOE Directives (requirements) were needed to direct IIIMS efforts but were never issued and the project has been halted. When restarted, duplicating or re-engineering the activities from 1999 to 2003 is unnecessary, and in fact future initiatives can build on previous work. IIIMS requirements should be structured to provide high confidence that discrepancies are detected, and classified information is not divulged. Enterprise-wide materials management systems maintained by the military can be used as overall models to base IIIMS implementation concepts upon.
We report low-dimensional tunneling in an independently contacted vertically coupled quantum wire system. This nanostructure is fabricated in a high quality GaAs/AlGaAs parallel double quantum well heterostructure. Using a unique flip chip technique to align top and bottom split gates to form low-dimensional constrictions in each of the independently contacted quantum wells we explicitly control the subband occupation of the individual wires. In addition to the expected two-dimensional (2D)-2D tunneling results, we have found additional tunneling features that are related to the one-dimensional quantum wires.
The impact of 3D structure on wire array z-pinch dynamics is a topic of current interest, and has been studied by the controlled seeding of wire perturbations. First, Al wires were etched at Sandia, creating 20% radial perturbations with variable axial wavelength. Observations of magnetic bubble formation in the etched regions during experiments on the MAGPIE accelerator are discussed and compared to 3D MHD modeling. Second, thin NaF coatings of 1 mm axial extent were deposited on Al wires and fielded on the Zebra accelerator. Little or no axial transport of the NaF spectroscopic dopant was observed in spatially resolved K-shell spectra, which places constraints on particle diffusivity in dense z-pinch plasmas. Finally, technology development for seeding perturbations is discussed.
This paper presents a 3D facial recognition algorithm based on the Hausdorff distance metric. The standard 3D formulation of the Hausdorff matching algorithm has been modified to operate on a 2D range image, enabling a reduction in computation from O(N2) to O(N) without large storage requirements. The Hausdorff distance is known for its robustness to data outliers and inconsistent data between two data sets, making it a suitable choice for dealing with the inherent problems in many 3D datasets due to sensor noise and object self-occlusion. For optimal performance, the algorithm assumes a good initial alignment between probe and template datasets. However, to minimize the error between two faces, the alignment can be iteratively refined. Results from the algorithm are presented using 3D face images from the Face Recognition Grand Challenge database version 1.0.
The U.S. Department of Energy's Radiological Threat Reduction (RTR) Program strives to reduce the threat of a Radiological Dispersion Device (RDD) incident that could affect U.S. interests worldwide. Sandia National Laboratories supports the RTR program on many different levels. Sandia works directly with DOE to develop strategies, including the selection of countries to receive support and the identification of radioactive materials to be protected. Sandia also works with DOE in the development of guidelines and in training DOE project managers in physical protection principles. Other support to DOE includes performing rapid assessments and providing guidance for establishing foreign regulatory and knowledge infrastructure. Sandia works directly with foreign governments to establish cooperative agreements necessary to implement the RTR Program efforts to protect radioactive sources. Once necessary agreements are in place, Sandia works with in-country organizations to implement various security related initiatives, such as installing security systems and searching for (and securing) orphaned radioactive sources. The radioactive materials of interest to the RTR program include Cobalt 60, Cesium 137, Strontium 90, Iridium 192, Radium 226, Plutonium 238, Americium 241, Californium 252, and Others. Security systems are implemented using a standardized approach that provides consistency through out the RTR program efforts at Sandia. The approach incorporates a series of major tasks that overlap in order to provide continuity. The major task sequence is to: Establish in-country contacts - integrators, Obtain material characterizations, Perform site assessments and vulnerability assessments, Develop upgrade plans, Procure and install equipment, Conduct acceptance testing and performance testing, Develop procedures, and Conduct training. Other tasks are incorporated as appropriate and commonly include such as support of reconfiguring infrastructure, and developing security plans, etc. This standardized approach is applied to specific country and regional needs. Recent examples (FY 2003-2004) include foreign missions to Lithuania, Russian Federation Navy, Russia - PNPI, Greece (joint mission with IAEA), Tanzania, Iraq, Chile, Ecuador, and Egypt. Some of the ambitions and results of the RTR program may be characterized by the successes in Lithuania, Greece, and Russia.
Recent 3D hybrid simulation of a plasma current-carrying column revealed two regimes of sausage and kink instability development. In the first regime, with small Hall parameter, development of instabilities leads to appearance of large-scale axial perturbations and eventually to the bending of the plasma column. In the second regime, with five times larger Hall parameter, small-scale perturbations dominated and no bending of the plasma column was observed. Simulation results are compared to recent experimental data, including laser probing, x-ray spectroscopy and time-gated x-ray imaging during wire array implosions at NTF.
This report documents the author's efforts in the deterministic modeling of copper-sulfidation corrosion on non-planar substrates such as diodes and electrical connectors. A new framework based on Goma was developed for multi-dimensional modeling of atmospheric copper-sulfidation corrosion on non-planar substrates. In this framework, the moving sulfidation front is explicitly tracked by treating the finite-element mesh as a pseudo solid with an arbitrary Lagrangian-Eulerian formulation and repeatedly performing re-meshing using CUBIT and re-mapping using MAPVAR. Three one-dimensional studies were performed for verifying the framework in asymptotic regimes. Limited model validation was also carried out by comparing computed copper-sulfide thickness with experimental data. The framework was first demonstrated in modeling one-dimensional copper sulfidation with charge separation. It was found that both the thickness of the space-charge layers and the electrical potential at the sulfidation surface decrease rapidly as the Cu{sub 2}S layer thickens initially but eventually reach equilibrium values as Cu{sub 2}S layer becomes sufficiently thick; it was also found that electroneutrality is a reasonable approximation and that the electro-migration flux may be estimated by using the equilibrium potential difference between the sulfidation and annihilation surfaces when the Cu{sub 2}S layer is sufficiently thick. The framework was then employed to model copper sulfidation in the solid-state-diffusion controlled regime (i.e. stage II sulfidation) on a prototypical diode until a continuous Cu{sub 2}S film was formed on the diode surface. The framework was also applied to model copper sulfidation on an intermittent electrical contact between a gold-plated copper pin and gold-plated copper pad; the presence of Cu{sub 2}S was found to raise the effective electrical resistance drastically. Lastly, future research needs in modeling atmospheric copper sulfidation are discussed.
Wind turbine system reliability is a critical factor in the success of a wind energy project. Poor reliability directly affects both the project's revenue stream through increased operation and maintenance (O&M) costs and reduced availability to generate power due to turbine downtime. Indirectly, the acceptance of wind-generated power by the financial and developer communities as a viable enterprise is influenced by the risk associated with the capital equipment reliability; increased risk, or at least the perception of increased risk, is generally accompanied by increased financing fees or interest rates. Cost of energy (COE) is a key project evaluation metric, both in commercial applications and in the U.S. federal wind energy program. To reflect this commercial reality, the wind energy research community has adopted COE as a decision-making and technology evaluation metric. The COE metric accounts for the effects of reliability through levelized replacement cost and unscheduled maintenance cost parameters. However, unlike the other cost contributors, such as initial capital investment and scheduled maintenance and operating expenses, costs associated with component failures are necessarily speculative. They are based on assumptions about the reliability of components that in many cases have not been operated for a complete life cycle. Due to the logistical and practical difficulty of replacing major components in a wind turbine, unanticipated failures (especially serial failures) can have a large impact on the economics of a project. The uncertainty associated with long-term component reliability has direct bearing on the confidence level associated with COE projections. In addition, wind turbine technology is evolving. New materials and designs are being incorporated in contemporary wind turbines with the ultimate goal of reducing weight, controlling loads, and improving energy capture. While the goal of these innovations is reduction in the COE, there is a potential impact on reliability whenever new technologies are introduced. While some of these innovations may ultimately improve reliability, in the short term, the technology risks and the perception of risk will increase. The COE metric used by researchers to evaluate technologies does not address this issue. This paper outlines the issues relevant to wind turbine reliability for wind turbine power generation projects. The first sections describe the current state of the industry, identify the cost elements associated with wind farm O&M and availability and discuss the causes of uncertainty in estimating wind turbine component reliability. The latter sections discuss the means for reducing O&M costs and propose O&M related research and development efforts that could be pursued by the wind energy research community to reduce COE.