Umbra is a new Sandia-developed modeling and simulation framework. The Umbra framework allows users to quickly build models and simulations for intelligent system development, analysis, experimentation, and control and supports tradeoff analyses of complex robotic systems, device, and component concepts. Umbra links together heterogeneous collections of modeling tools. The models in Umbra include 3D geometry and physics models of robots, devices and their environments. Model components can be built with varying levels of fidelity and readily switched to allow models built with low fidelity for conceptual analysis to be gradually converted to high fidelity models for later phase detailed analysis. Within control environments, the models can be readily replaced with actual control elements. This paper describes Umbra at a functional level and describes issues that Sandia uses Umbra to address.
The construction of inverse states in a finite field F{sub P{sub P{alpha}}} enables the organization of the mass scale by associating particle states with residue class designations. With the assumption of perfect flatness ({Omega}total = 1.0), this approach leads to the derivation of a cosmic seesaw congruence which unifies the concepts of space and mass. The law of quadratic reciprocity profoundly constrains the subgroup structure of the multiplicative group of units F{sub P{sub {alpha}}}* defined by the field. Four specific outcomes of this organization are (1) a reduction in the computational complexity of the mass state distribution by a factor of {approximately}10{sup 30}, (2) the extension of the genetic divisor concept to the classification of subgroup orders, (3) the derivation of a simple numerical test for any prospective mass number based on the order of the integer, and (4) the identification of direct biological analogies to taxonomy and regulatory networks characteristic of cellular metabolism, tumor suppression, immunology, and evolution. It is generally concluded that the organizing principle legislated by the alliance of quadratic reciprocity with the cosmic seesaw creates a universal optimized structure that functions in the regulation of a broad range of complex phenomena.
This report describes the use of PorSalsa, a parallel-processing, finite-element-based, unstructured-grid code for the simulation of subsurface nonisothermal two-phase, two component flow through heterogeneous porous materials. PorSalsa can also model the advective-dispersive transport of any number of species. General source term and transport coefficient implementation greatly expands possible applications. Spatially heterogeneous flow and transport data are accommodated via a flexible interface. Discretization methods include both Galerkin and control volume finite element methods, with various options for weighting of nonlinear coefficients. Time integration includes both first and second-order predictor/corrector methods with automatic time step selection. Parallel processing is accomplished by domain decomposition and message passing, using MPI, enabling seamless execution on single computers, networked clusters, and massively parallel computers.
Arithmetic conditions relating particle masses can be defined on the basis of (1) the supersymmetric conservation of congruence and (2) the observed characteristics of particle reactions and stabilities. Stated in the form of common divisors, these relations can be interpreted as expressions of genetic elements that represent specific particle characteristics. In order to illustrate this concept, it is shown that the pion triplet ({pi}{sup {+-}}, {pi}{sup 0}) can be associated with the existence of a greatest common divisor d{sub 0{+-}} in a way that can account for both the highly similar physical properties of these particles and the observed {pi}{sup {+-}}/{pi}{sup 0} mass splitting. These results support the conclusion that a corresponding statement holds generally for all particle multiplets. Classification of the respective physical states is achieved by assignment of the common divisors to residue classes in a finite field F{sub P{sub {alpha}}} and the existence of the multiplicative group of units F{sub P{sub {alpha}}} enables the corresponding mass parameters to be associated with a rich subgroup structure. The existence of inverse states in F{sub P{sub {alpha}}} allows relationships connecting particle mass values to be conveniently expressed in a form in which the genetic divisor structure is prominent. An example is given in which the masses of two neutral mesons (K{degree} {r_arrow} {pi}{degree}) are related to the properties of the electron (e), a charged lepton. Physically, since this relationship reflects the cascade decay K{degree} {r_arrow} {pi}{degree} + {pi}{degree}/{pi}{degree} {r_arrow} e{sup +} + e{sup {minus}}, in which a neutral kaon is converted into four charged leptons, it enables the genetic divisor concept, through the intrinsic algebraic structure of the field, to provide a theoretical basis for the conservation of both electric charge and lepton number. It is further shown that the fundamental source of supersymmetry can be expressed in terms of hierarchical relationships between odd and even order subgroups of F{sub P{sub {alpha}}}, an outcome that automatically reflects itself in the phenomenon of fermion/boson pairing of individual particle systems. Accordingly, supersymmetry is best represented as a group rather than a particle property. The status of the Higgs subgroup of order 4 is singular; it is isolated from the hierarchical pattern and communicates globally to the mass scale through the seesaw congruence by (1) fusing the concepts of mass and space and (2) specifying the generators of the physical masses.
The stress of scandium dideuteride, ScD{sub 2}, thin films is investigated during each stage of vacuum processing including metal deposition via evaporation, reaction and cooldown. ScD{sub 2} films with thin Cr underlayers are fabricated on three different substrate materials: molybdenum-alumina cermet, single crystal sapphire and quartz. In all experiments, the evaporated Cr and Sc metal is relatively stress-free. However, reaction of scandium metal with deuterium at elevated temperature to form a stoichiometric dideuteride phase leads to a large compressive in-plane film stress. Compression during hydriding results from an increased atomic density compared with the as-deposited metal film. After reaction with deuterium, samples are cooled to ambient temperature, and a tensile stress develops due to mismatched coefficients of thermal expansion (CTE) of the substrate-film couple. The residual film stress and the propensity for films to crack during cooldown depends principally on the substrate material when using identical process parameters. Films deposited onto quartz substrates show evidence of stress relief during cooldown due to a large CTE misfit; this is correlated with crack nucleation and propagation within films. All ScD{sub 2} layers remain in a state of tension when cooled to 30 C. An in-situ, laser-based, wafer curvature sensor is designed and implemented for studies of ScD{sub 2} film stress during processing. This instrument uses a two-dimensional array of laser beams to noninvasively monitor stress during sample rotation and with samples stationary. Film stress is monitored by scattering light off the backside of substrates, i.e., side opposite of the deposition flux.
An experiment to measure surface pressure data on a series of three stainless steel simulated parachute ribbons was conducted. During the first phase of the test, unsteady pressure measurements were made on the windward and leeward sides of the ribbons to determine the statistical properties of the surface pressures. Particle Image Velocimetry (PIV) measurements were simultaneously made to establish the velocity field in the wake of the ribbons and its correlation with the pressure measurements. In the second phase of the test, steady-state pressure measurements were made to establish the pressure distributions. In the third phase, the stainless steel ribbons were replaced with nylon ribbons and PIV measurements were made in the wake. A detailed error analysis indicates that the accuracy of the pressure measurements was very good. However, an anomaly in the flow field caused the wake behind the stainless steel ribbons to establish itself in a stable manner on one side of the model. This same stability was not present for the nylon ribbon model although an average of the wake velocity data indicated an apparent 2{degree} upwash in the wind tunnel flow field. Since flow angularity upstream of the model was not measured, the use of the data for code validation is not recommended without a second experiment to establish that upstream boundary condition.
In support of two major SNL programs, the Long-term Inflow and Structural Test (LIST) program and the Blade Manufacturing Initiative (BMI), three Micon 65/13M wind turbines have been erected at the USDA Agriculture Research Service (ARS) center in Bushland, Texas. The inflow and structural response of these turbines are being monitored with an array of 60 instruments: 34 to characterize the inflow, 19 to characterize structural response and 7 to characterize the time-varying state of the turbine. The primary characterization of the inflow into the LIST turbine relies upon an array of five sonic anemometers. Primary characterization of the structural response of the turbine uses several sets of strain gauges to measure bending loads on the blades and the tower and two accelerometers to measure the motion of the nacelle. Data are sampled at a rate of 30 Hz using a newly developed data acquisition system. The system features a time-synchronized continuous data stream and telemetered data from the turbine rotor. This paper documents the instruments and infrastructure that have been developed to monitor these turbines and their inflow.
Numerical methods may require derivatives of functions whose values are known only on irregularly spaced calculation points. This document presents and quantifies the performance of Moving Least-Squares (MLS), a method of derivative evaluation on irregularly spaced points that has a number of inherent advantages. The user selects both the spatial dimension of the problem and order of the highest conserved moment. The accuracy of calculations is maintained on highly irregularly spaced points. Not required are creation of additional calculation points or interpolation of the calculation points onto a regular grid. Implementation of the method requires the use of only a relatively small number of calculation points. The method is fast, robust and provides smooth results even as the order of the derivative increases.
Meso-scale manufacturing processes are bridging the gap between silicon-based MEMS processes and conventional miniature machining. These processes can fabricate two and three-dimensional parts having micron size features in traditional materials such as stainless steels, rare earth magnets, ceramics, and glass. Meso-scale processes that are currently available include, focused ion beam sputtering, micro-milling, micro-turning, excimer laser ablation, femtosecond laser ablation, and micro electro discharge machining. These meso-scale processes employ subtractive machining technologies (i.e., material removal), unlike LIGA, which is an additive meso-scale process. Meso-scale processes have different material capabilities and machining performance specifications. Machining performance specifications of interest include minimum feature size, feature tolerance, feature location accuracy, surface finish, and material removal rate. Sandia National Laboratories is developing meso-scale mechanical components and actuators which require meso-scale parts fabricated in a variety of materials. Subtractive meso-scale manufacturing processes expand the functionality of meso-scale components and complement silicon based MEMS and LIGA technologies.
This technical report presents the initial proposal and renewable proposals for an LDRD project whose intended goal was to enable applications to take full advantage of the hardware available on Sandia's current and future massively parallel supercomputers by analyzing various ways of combining distributed-memory and shared-memory programming models. Despite Sandia's enormous success with distributed-memory parallel machines and the message-passing programming model, clusters of shared-memory processors appeared to be the massively parallel architecture of the future at the time this project was proposed. They had hoped to analyze various hybrid programming models for their effectiveness and characterize the types of application to which each model was well-suited. The report presents the initial research proposal and subsequent continuation proposals that highlight the proposed work and summarize the accomplishments.
This paper studies the implementation of polar format, synthetic aperture radar image formation in modern Field Programmable Gate Arrays (FPGA's). The polar format algorithm is described in rough terms and each of the processing steps is mapped to FPGA logic. This FPGA logic is analyzed with respect to throughput and circuit size for compatibility with airborne image formation.
The progress in the fabrication of high voltage GaN and AlGaN rectifiers, GaN/AlGaN HBT and GaN MOSFET is reviewed. Improvements in epitaxial layer quality are studied. The advances in fabrication techniques that led to the improvement of device performance are discussed.
This paper documents work performed to convert scanned range data to CAD solid model representation. The work successfully developed surface fitting algorithms for quadric surfaces (e.g. plane, cone, cylinder, and sphere), and a segmentation algorithm based entirely on surface type, rather than on a differential metric like Gaussian curvature. Extraction of all CAD-required parameters for quadric surface representation was completed. Approximate face boundaries derived from the original point cloud were constructed. Work to extrapolate surfaces, compute exact edges and solid connectivity was begun, but left incomplete due to funding reductions. The surface fitting algorithms are robust in the face of noise and degenerate surface forms.
As part of a project with SEMATECH, detailed chemical reaction mechanisms have been developed that describe the gas-phase and surface chemistry occurring during the fluorocarbon plasma etching of silicon dioxide and related materials. The fluorocarbons examined are C{sub 2}F{sub 6}, CHF{sub 3} and C{sub 4}F{sub 8}, while the materials studied are silicon dioxide, silicon, photoresist, and silica-based low-k dielectrics. These systems were examined at different levels, ranging from in-depth treatment of C{sub 2}F{sub 6} plasma etch of oxide, to a fairly cursory examination of C{sub 4}F{sub 8} etch of the low-k dielectric. Simulations using these reaction mechanisms and AURORA, a zero-dimensional model, compare favorably with etch rates measured in three different experimental reactors, plus extensive diagnostic absolute density measurements of electron and negative ions, relative density measurements of CF, CF{sub 2}, SiF and SiF{sub 2} radicals, ion current densities, and mass spectrometric measurements of relative ion densities.
As computers become faster, have more memory, and use multiple parallel processors, large, complex codes that more accurately simulate physical phenomena have emerged to utilize this capability. Most problems can benefit from this approach and many require it. But not all! There are problems for which simpler methods on more modest computers still work. The trick is to identify those problems, write the codes, and make their implementation sufficiently simple that they can be used conveniently by those who could profit from them. A Simple Plasma Code has been written with this philosophy in mind. It retains just enough physics to allow realistic simulations to be formulated and run quickly, even on a personal computer. This paper describes the physical model, its numerical implementation, and presents a sample simulation.
Window and free surface interfaces perturb the flow in compression wave experiments. The velocity of these interfaces is routinely measured in shock-compression experiments using interferometry (i.e., VISAR). Interface perturbations often must be accounted for before meaningful material property results can be obtained. For shockless experiments when stress is a single valued function of strain, the governing equations of motion are hyperbolic and can be numerically integrated forward or backward in either time or space with assured stability. Using the VISAR results as ''initial conditions'' the flow fields are integrated backward in space to the interior of the specimen where the VISAR interface has not perturbed the flow at earlier times and results can be interpreted as if the interface had not been present. This provides a rather exact correction for free surface perturbations. The method can also be applied to window interfaces by selecting the appropriate initial conditions. Applications include interpreting Z-accelerator ramp wave experiments. The method applies to multiple layers and multiple reverberations. For an elastic-plastic material model the flow is dissipative and the governing equations are parabolic. When the parabolic terms are small, the equations also can be successfully integrated backward in space. This is verified by using a traditional elastic-plastic wave propagation code with a backward-derived stress history as the boundary condition for a forward calculation. Calculated free surface histories match the starting VISAR record verifying that the backward method produced an accurate solution to the governing equations. With our cooperation, workers at Los Alamos have successfully applied the Sandia-developed backward technique for the time-dependent quasielastic material model and are analyzing stress histories at a spall plane using the VISAR free surface velocity measurement from a ''pullback'' experiment.
Superresolution concepts offer the potential of resolution beyond the classical limit. This great promise has not generally been realized. In this study we investigate the potential application of superresolution concepts to synthetic aperture radar. The analytical basis for superresolution theory is discussed. The application of the concept to synthetic aperture radar is investigated as an operator inversion problem. Generally, the operator inversion problem is ill posed. A criterion for judging superresolution processing of an image is presented.
This report is a supplement to ''The Unique Signal Concept for Detonation Safety in Nuclear Weapons,'' SAND91-1269, which provides a prerequisite fundamental background on the unique signal (UQS) concept. The UQS is one of the key constituents of Enhanced Nuclear Detonation Safety (ENDS), as outlined in Section 1 of that report. There have been many documents written over the past quarter of a century describing various aspects of the UQS, but none of these emphasized the mathematical approaches that help explain why the UQS is effective in resisting inadvertent pre-arming, even in abnormal environments and how UQS implementations can be quantitatively assessed. The intent of this report is to describe various pertinent mathematical methodologies (many of which have not been previously reported) without duplicating, any more than necessary, background information available in other reports. Mathematical UQS analysis is needed because of quantitative requirements associated with ENDS, and because limited comparisons of various implementation approaches can be quantified under mathematical modeling assumptions. Some of the mathematics-based results shown in this report are presented to explain: (1) The reasons that the UQS methodology can provide greater protection against accident environments than could combinational techniques (Sections 2.1 through 2.4); (2) The reason that the probability of inadvertently duplicating a UQS comprising n bivalued events cannot be estimated as low as (1/2) inches (Section 2.4); (3) The value of, and the Sandia National Laboratories policy on independent sequential communication of UQS events (Section 3.4); and (4) The care that must be exercised if any signal processing is necessary (Section 4). There are also numerous examples (e.g., in Appendices A and B) of ill-advised deviations from UQS methodology that can seriously degrade safety. These examples help demonstrate that the UQS methodology should not be compromised.
Dual control volume molecular dynamics was employed to study the flux of methane through channels of thin silicalite membranes. The DCANIS force field was analyzed to describe the adsorption isotherms of methane and ethane in silicalite. The alkane parameters and silicalite parameters were determined by fiiting the DCANIS force field to single-component vapor-liquid coexistence curves (VLCC) and adsorption isotherms respectively. The adsorption layers on the surfaces of thin silicalite membranes showed a sifnificant resistance to the flux of methane. The results depicted the insensitivity of permeance to both the average pressure and pressure drop.
For highly cross-linked polymer networks bonded to a solid surface, the effect of interfacial bond density and system size on interfacial fracture is studied using molecular dynamics simulations. Results for tensile and shear mode simulations are given. The correspondence between the stress-strain curve and the sequence of molecular deformations is obtained. The failure strain for a fully bonded surface is equal to the strain necessary to make taut the average of the minimal paths through the network from a bonded site on the bottom solid surface to a bonded site on the top surface. At fractional interfacial bond densities, cavities form above the nonbonded surface, yielding an inhomogeneous strain profile and a smaller failure strain. The failure strain and stress are linearly proportional to the number of bonds at the interface except in the tensile mode when number of bonds is so few that van der Waals interactions dominate. The failure mode is successfully constructed to be interracial by limiting the interfacial bond density to be less than the bulk bond density.
Advanced thin-film processing and packaging technologies are employed in the fabrication of new planar thin-film multijunction thermal converters (MJTCs). The processing, packaging, and design features build on experience gained from prior NIST demonstrations of thin-film converters and are optimized for improved sensitivity, bandwidth, manufacturability, and reliability.
This case study describes a success in technology transfer out of Sandia National Laboratories that resulted in commercialization supporting both the laboratories' national security mission and economic development. This case exemplifies how the process of technology innovation stretches from national legislation to laboratory management to entrepreneurs, and then out into the community where the technology must be developed and commercialized if innovation is to occur. Two things emerged from the research for this case study that have implications for technology transfer and commercialization from other national laboratories and may also be relevant to technology commercialization out of other federal laboratories and universities. The first is the very clear theme that partnerships were critical to the ultimate successful commercialization of the technology--partnerships between public and private research groups as well as between business development groups. The second involves identifiable factors that played a role in moving the process forward to successful commercialization. All of the factors, with two significant exceptions, focused on technology and business development directly related to creating research and business partnerships. The two exceptions, a technology with significant market applications, and entrepreneurs willing and able to take the risks and accomplish the hard work of technology innovation, were initiating requirements for the process.
The Sandia Photovoltaic Program conducted research in crystalline-silicon solar cells between 1986 and 2000 for the U.S. Department of Energy. This period saw rapid improvements in the fundamental understanding of c-Si materials and devices, improvements in c-Si PV manufacturing and control, and a rapid expansion of c-Si PV manufacturing capacity. Crystalline-silicon technology has provided the basis for PV to emerge as a serious option for global energy needs. The c-Si cell research at Sandia examined c-Si materials, devices, processing, and process integration. This report summarizes research conducted in this program over the past 15 years.
Despite the end of the Cold War, the US and Russia continue to maintain their ICBMs and many SLBMs in a highly alerted state--they are technically prepared to launch the missiles within minutes of a command decision to do so. Some analysts argue that, particularly in light of the distressed condition of the Russian military, these high alert conditions are tantamount to standing on the edge of a nuclear cliff from which we should now step back. They have proposed various bilateral ''de-alerting'' measures, to be taken prior to and outside the context of the formal strategic arms reduction treaty (START) process. This paper identifies several criteria for a stable de-alerting regime, but fails to find de-alerting measures that convincingly satisfy the criteria. However, some de-alerting measures have promise as de-activation measures for systems due for elimination under the START II and prospective START III treaties. Moreover, once these systems are deactivated, a considerable part of the perceived need to keep nuclear forces on high alert as a survivability hedge will be reduced. At the same time, the U.S. and Russia could consider building on their earlier cooperative actions to reduce the risk of inadvertent nuclear war by enhancing their communications links and possibly joining in efforts to improve early warning systems.
The authors have developed novel metal-assisted texturing processes that have led to optically favorable surfaces for solar cells. Large area ({approximately} 200 cm{sup 2}) uniform texturing has been achieved. The physical dimensions of the chamber limited texturing of even larger wafers. Surface contamination and residual RIE-induced damage were removed by incorporation of a complete RCA clean process followed by wet-chemical etching treatments. RIE-textured solar cells with optimized profiles providing performance comparable to the random, wet-chemically etched cells have been demonstrated. A majority of the texture profiles exhibit an enhanced IQE response in the near IR region.using scanning electron microscope measurements, they carried out a detailed analysis of the microstructure of random RIE-textured surfaces. The random microstructure represents a superposition of sub-{micro}m grating structures with a wide distribution of periods, depths, and profiles as determined by the SEM measurements. These structures were modeled using GSOLVER{trademark} software for periodic patterns. The enhanced IR response from random, RIE-textured surfaces is attributed to enhanced coupling of light into the transmitted diffraction orders. These obliquely propagating diffraction orders generate electron-hole pairs closer to the surface, thus, reducing bulk recombination losses relative to a non-scattering, planar surface with identical hemispherical reflection. The optimized texture and damage removal processes have been applied to large area (100--132 cm{sup 2}) multi-crystalline wafers. initial results have demonstrated improved performance relative to planar, control wafers. However, the texture and solar cell fabrication processes require further optimization in the RCA clean, DRE treatments, and emitter formation in order to fully realize the benefits of the low-reflection ({approximately}1-2%) textured surfaces.
We have used selective AlGaAs oxidation, dry-etching, and high-gain semiconductor laser simulation to create new in-plane lasers with interconnecting passive waveguides for use in high-density photonic circuits and future integration of photonics with electronics. Selective oxidation and doping of semiconductor heterostructures have made vertical cavity surface emitting lasers (VCSELs) into the world's most efficient low-power lasers. We apply oxidation technology to improve edge-emitting lasers and photonic-crystal waveguides, making them suitable for monolithic integrated microsystems. Two types of lasers are investigated: (1) a ridge laser with resonant coupling to an output waveguide; (2) a selectively-oxidized laser with a low active volume and potentially sub-milliAmp threshold current. Emphasis is on development of high-performance lasers suited for monolithic integration with photonic circuit elements.
Ion implantation of O and Al were used to form nanometer-size precipitates of NiO or Al{sub 2}O{sub 3} in the near-surface of Ni. The yield strengths of the treated layers were determined by nanoindentation testing in conjunction with finite-element modeling. The strengths range up to {approximately}5 GPa, substantially above values for hard bearing steels. These results agree quantitatively with predictions of dispersion-hardening theory based on the precipitate microstructures observed by transmission electron microscopy. Such surface hardening by ion implantation may be beneficial for Ni components in micro-electromechanical systems.
An effort is underway at Sandia National Laboratories to develop a library of algorithms to search for potential interactions between surfaces represented by analytic and discretized topological entities. This effort is also developing algorithms to determine forces due to these interactions for transient dynamics applications. This document describes the Application Programming Interface (API) for the ACME (Algorithms for Contact in a Multiphysics Environment) library.
The type of polymeric material used in the manufacturing of tubing determines its strength, elasticity, and durability. Tubing made of polymeric material is commonly used for analytical work because it is readily available, inexpensive and can be relatively inert. Polymeric tubing is used in many sampling applications for explosive compounds. A major concern is the uptake of the explosive compounds into or onto the tubing during sampling. Because of the reactive nature of explosives, it is important that as little of the detectable explosive as possible is lost by tubing uptake. It is also important that nothing leaches out of the tubing to interfere with the detection of explosives. High Performance Liquid Chromatography (HPLC) is commonly used for the analysis of trace levels of explosive compounds in the range of parts per billion (ppb) to parts per million (ppm). This study attempts to determine which types of polymers are most conducive to sampling applications where large volumes of dilute explosive solutions are collected through a length of tubing for analysis. This was determined by analyzing the amount of explosive lost from solution per cm{sup 2} of tubing in solution. It was determined that tubing made of polyethylene, teflon, polypropylene, or KYNAR{reg_sign} is recommended for dilute trinitrotoluene (TNT) solution analyses. Tubing made of polypropylene, PHARMED{reg_sign}, KYNAR{reg_sign}, or polyethylene is recommended for analyses involving dilute explosive solutions of RDX. Tubing made from polyurethane, TYGON{reg_sign}, nylon, vinyl, gum rubber, or reinforced PVC are not recommended because they leach contaminants into solution that may interfere with HPLC analysis of explosive peaks.
The next major performance plateau for high-speed, long-haul networks is at 10 Gbps. Data visualization, high performance network storage, and Massively Parallel Processing (MPP) demand these (and higher) communication rates. MPP-to-MPP distributed processing applications and MPP-to-Network File Store applications already require single conversation communication rates in the range of 10 to 100 Gbps. MPP-to-Visualization Station applications can already utilize communication rates in the 1 to 10 Gbps range. This LDRD project examined some of the building blocks necessary for developing a 10 to 100 Gbps computer network architecture. These included technology areas such as, OS Bypass, Dense Wavelength Division Multiplexing (DWDM), IP switching and routing, Optical Amplifiers, Inverse Multiplexing of ATM, data encryption, and data compression; standards bodies activities in the ATM Forum and the Optical Internetworking Forum (OIF); and proof-of-principle laboratory prototypes. This work has not only advanced the body of knowledge in the aforementioned areas, but has generally facilitated the rapid maturation of high-speed networking and communication technology by: (1) participating in the development of pertinent standards, and (2) by promoting informal (and formal) collaboration with industrial developers of high speed communication equipment.
The NEWPEP thermochemical code is a computer program that has been developed to help predict the performance of a user generated propellant system. Sandia has used the program to model the use of different oxidizer/fuel combinations. The program has been adapted to fit Sandia's need by expanding the programs combustion species database and the ingredient list. This paper provides the user with a thorough set of operating instructions.
Several years ago Sandia National Laboratories developed a prototype interior robot [1] that could navigate autonomously inside a large complex building to aid and test interior intrusion detection systems. Recently the Department of Energy Office of Safeguards and Security has supported the development of a vehicle that will perform limited security functions autonomously in a structured exterior environment. The goal of the first phase of this project was to demonstrate the feasibility of an exterior robotic vehicle for security applications by using converted interior robot technology, if applicable. An existing teleoperational test bed vehicle with remote driving controls was modified and integrated with a newly developed command driving station and navigation system hardware and software to form the Robotic Security Vehicle (RSV) system. The RSV, also called the Sandia Mobile Autonomous Navigator (SANDMAN), has been successfully used to demonstrate that teleoperated security vehicles which can perform limited autonomous functions are viable and have the potential to decrease security manpower requirements and improve system capabilities.
This report provides a brief summary of the characteristics of contemporary high-power microwave sources. The focus is on their physical and operational characteristics and regions of application rather than their theory of operation. Magnetrons, linear beam tubes, split-cavity oscillators, virtual cathode oscillators, gyrotrons, free-electron lasers, and orbitron microwave masers are described. Power supply requirements and engineering issues of the application of HPM devices are addressed.
In support of the Cassini Mission Final Safety Analysis Report (FSAR), Sandia National Laboratories (SNL) was requested by Lockheed Martin Corporation (LMC) to investigate for various scenarios, the distribution of aerosol and particulate mass in a stabilized buoyant plume created as a result of a fireball explosion. The information obtained from these calculations is to provide background information for the radiological consequence analysis of the FSAR. Specifically, the information is used to investigate the mass distribution within the ''cap and stem'' portions of the initial fireball plume, a modeling feature included in the SATRAP module in the LMC SPARRC code. The investigation includes variation of the plume energy and the application of several meteorological conditions for a total of seven sensitivity case studies. For each of the case studies, the calculations were performed for two configurations of particle mass in the plume (total mass and plutonium mass).
The DAKOTA (Design Analysis Kit for Optimization and Terascale Applications) toolkit provides a flexible and extensible interface between simulation codes and iterative analysis methods. DAKOTA contains algorithms for optimization with gradient and nongradient-based methods; uncertainty quantification with sampling, analytic reliability, and stochastic finite element methods; parameter estimation with nonlinear least squares methods; and sensitivity analysis with design of experiments and parameter study methods. These capabilities may be used on their own or as components within advanced strategies such as surrogate-based optimization, mixed integer nonlinear programming, or optimization under uncertainty. By employing object-oriented design to implement abstractions of the key components required for iterative systems analyses, the DAKOTA toolkit provides a flexible and extensible problem-solving environment for design and performance analysis of computational models on high performance computers. This report serves as a reference manual for the commands specification for the DAKOTA software, providing input overviews, option descriptions, and example specifications.
Steady and oscillatory shear 3-D simulations of electro- and magnetorheology in uniaxial and biaxial fields are presented, and compared to the predictions of the chain model. These large scale simulations are three dimensional, and include the effect of Brownian motion. In the absence of thermal fluctuations, the expected shear thinning viscosity is observed in steady shear, and a striped phase is seen to rapidly form in a uniaxial field, with a shear slip zone in each sheet. However, as the influence of Brownian motion increases, the fluid stress decreases, especially at lower Mason numbers, and the striped phase eventually disappears, even when the fluid stress is still high. In a biaxial field, an opposite trend is seen, where Brownian motion decreases the stress most significantly at higher Mason numbers. To account for the uniaxial steady shear data we propose a microscopic chain model of the role played by thermal fluctuations on the rheology of ER and MR fluids that delineates the regimes where an applied field can impact the fluid viscosity, and gives an analytical prediction for the thermal effect. In oscillatory shear, a striped phase again appears in a uniaxial field, at strain amplitudes greater than ∼0.15, and the presence of a shear slip zone creates strong stress nonlinearities at low strain amplitudes. In a biaxial field, a shear slip zone is not created, and so the stress nonlinearities develop only at expected strain amplitudes. The nonlinear dynamics of these systems is shown to be in good agreement with the Kinetic Chain Model.
In this study, twelve embedded atom method (EAM) function sets were tested for their ability to predict liquid/vapor surface tension. Testing was carried out in the isochoric-isothermal (NVT) ensemble with a Berendsen thermostat. It was shown that the use of charge gradient corrections in conjunction with appropriate EAM functions provide surface property predictions in excellent agreement with experiment for solid and liquid metals.
A method for decomposing a volume with a prescribed quadrilateral surface mesh, into a hexahedral-dominated mesh is proposed. With this method, known as Hex-Morphing (H-Morph), an initial tetrahedral mesh is provided. Tetrahedra are transformed and combined starting from the boundary and working towards the interior of the volume. The quadrilateral faces of the hexahedra are treated as internal surfaces, which can be recovered using constrained triangulation techniques. Implementation details of the edge and face recovery process are included. Examples and performance of the H-Morph algorithm are also presented.
Remarkable materials ordered at the nano scale emerge when a sol-gel solution becomes co-organized with a surfactant. At sufficiently high concentration, the surfactant forms crystalline or liquid-crystalline arrays of micelles in the presence of the sol-gel, and as gelation proceeds the arrays become locked into the gel. Recent experiments demonstrate that the degree of order in the resulting mesoporous ceramic phase can be enhanced and controlled by continuous dip coating in which the solution, initially dilute, evolves through the critical micelle concentration by steady-state evaporation. The long-range order and microstructural orientation in these films suggest that the propagation of a critical-micelle-concentration transition front, with large physico-chemical gradients, promotes oriented self assembly of surfactant aggregates. This "steep-gradient" view is supported by results from unsteady evaporation of aerosols of similar solutions, in which internally well-ordered but complex particles are formed.
Remarkable materials ordered at the nano scale emerge when a sol-gel solution becomes co-organized with a surfactant. At sufficiently high concentration, the surfactant forms crystalline or liquid-crystalline arrays of micelles in the presence of the sol-gel, and as gelation proceeds the arrays become locked into the gel. Recent experiments demonstrate that the degree of order in the resulting mesoporous ceramic phase can be enhanced and controlled by continuous dip coating in which the solution, initially dilute, evolves through the critical micelle concentration by steady-state evaporation. The long-range order and microstructural orientation in these films suggest that the propagation of a critical-micelle-concentration transition front, with large physico-chemical gradients, promotes oriented self assembly of surfactant aggregates. This "steep-gradient" view is supported by results from unsteady evaporation of aerosols of similar solutions, in which internally well-ordered but complex particles are formed.
We have demonstrated the dc and rf characteristics of a novel p-n-p GaAs/InGaAsN/GaAs double heterojunction bipolar transistor. This device has near ideal current-voltage (I-V) characteristics with a current gain greater than 45. The smaller bandgap energy of the InGaAsN base has led to a device turn-on voltage that is 0.27 V lower than in a comparable p-n-p AlGaAs/GaAs heterojunction bipolar transistor. This device has shown f T and f MAX values of 12 GHz. In addition, the aluminum-free emitter structure eliminates issues typically associated with AlGaAs.
Contaminant release scenarios proposed for the Waste Isolation Pilot Plant (WIPP) repository suggest that the Culebra Dolomite member of the Rustler Formation could be an important radionuclide release path. This thin, vuggy, highly fractured unit is the most transmissive geologic unit overlying the WIPP. Many of the samples obtained from drill cores in the Culebra exhibit fractures that are lined with iron-oxyhydroxide-rich and clay-rich mineral coatings. The coatings are mineralogically distinct from the rock matrix, and may have sorptive characteristics that are different from a clay-poor dolomite matrix. Where locally abundant, such coatings could affect advective/diffusive exchange between matrix blocks and fractures and the accessible mineral surface area available for radionuclide adsorption. Clay minerals are present in the matrix and as fracture coatings in the samples from all the drill core locations examined in this study. Visual examination of rock sample surfaces in the H -19b7 core suggests that at least 7% of the total fracture surface area is coated with iron oxhydroxides or clays. In the samples from H-19b7, the amount of clay disseminated in the matrix varies from <1% to {approx}12 % by weight, and generally increases with stratigraphic height within the unit. In a suite of samples obtained from 12 other locations in the vicinity of the WIPP site, matrix samples from the Culebra contain 0.6--7% clay. These samples were taken from the more transmissive lower two-thirds of the unit (Culebra Units 2-4) which was considered to be the accessible portion of the unit in the WIPP Compliance Certification Application (CCA). Clay minerals also occur as clay-rich laminae and partings with the geometries of primary sedimentary structures and dissolution residues. Such partings are the loci of bedding plane fractures, and have the heaviest clay coatings found in the unit. Crosscutting fractures also commonly exhibit clay mineral coatings, but these are generally discontinuous and much thinner.
The restructuring of the U.S. power industry will surely lead to a greater dependence on computers and communications to allow appropriate information sharing for management and control of the power grid. This report describes the operating environment for system operations that control the bulk power system as it exists today including the role NERC plays in this process. Some high-level functional requirements for new approaches to control of the grid are listed followed by a description of the next research steps that are needed to identify specific information management functions.
Intelligent agents and multi-agent systems promise to take information management for real-time control of the power grid to a new level. This report presents our concept for intelligent agents to mediate and coordinate communications between Control Areas and Security Coordinators for real-time control of the power grid. An appendix describes the organizations and publications that deal with agent technologies.
Magnesium vanadates are potentially important catalytic materials for the conversion of alkanes to alkenes via oxidative dehydrogenation. However, little is known about the active sites at which the catalytic reactions take place. It may be possible to obtain a significant increase in the catalytic efficiency if the effects of certain material properties on the surface reactions could be quantified and optimized through the use of appropriate preparation techniques. Given that surface reactivity is often dependent upon surface structure and that the atomic level structure of the active sites in these catalysts is virtually unknown, we desire thin film samples consisting of a single magnesium vanadate phase and a well defined crystallographic orientation in order to reduce complexity and simplify the study of active sites. This report describes the use of reactive RF sputter deposition to fabricate very highly oriented, stoichiometric Mg{sub 3}(VO{sub 4}){sub 2} thin films, and subsequent studies of the reactivity of these films under reaction conditions typically found during oxidative dehydrogenation. We demonstrate that the synthesis methods employed do in fact result in stoichiometric films with the desired crystallographic orientation, and that the chemical behavior of the films closely approximates that of bulk, high surface area Mg{sub 3}(VO{sub 4}){sub 2} powders. We further use these films to demonstrate the effects of oxygen vacancies on chemical behavior, demonstrate that surface composition can vary significantly under reaction conditions, and obtain the first evidence for structure sensitivity in Mg{sub 3}(VO{sub 4}){sub 2} catalysts.
Consider a system of rigid bodies with multiple concurrent contacts. The multi-rigid-body contact problem is to predict the accelerations of the bodies and the normal friction loads acting at the contacts. This paper presents theoretical results for the multi-rigid-body contact problem under the assumptions that one or more contacts occur over locally planar, finite regions and that friction forces are consistent with the maximum work inequality. Existence and uniqueness results are presented for this problem under mild assumptions on the system inputs. In addition, the performance of two different time-stepping methods for integrating the dynamics are compared on two simple multi-body systems.
In this study, the erosion rates of four reconstituted sediments in both rectangular and circular sample tubes have been determined as a function of density and shear stress by means of a high shear stress sediment erosion flume at Sandia National Laboratories. This was done to determine if circular cores used in field sampling would provide the same results found using the existing technology of rectangular cores. Two samples were natural, cohesive sediments retrieved from different sites in the Boston Harbor identified as Open Cell and Mid Channel. The other two sediments were medium and coarse grain, non-cohesive quartz sediments. For each sediment type, erosion tests were performed with both rectangular and circular core tubes. For all cores, bulk density was determined as a function of depth and consolidation time. Sediments were eroded to determine erosion rates as a function of density and shear stress for both types of core tubes used. No measurable difference was found between the two core types.
Sandia National Laboratories has sponsored an LDRD (Laboratory Directed Research and Development) project to investigate and develop micro-chemical sensors for in-situ monitoring of subsurface contaminants. As part of this project, a literature search has been conducted to survey available technologies and identify the most promising methods for sensing and monitoring subsurface contaminants of interest. Specific sensor technologies are categorized into several broad groups, and these groups are then evaluated for use in subsurface, long-term applications. This report introduces the background and specific scope of the problem being addressed by this LDRD project, and it provides a summary of the advantages and disadvantages of each sensor technology identified from the literature search.
Atomistic simulations of the growth of helium bubbles in metals are performed. The metal is represented by embedded atom method potentials for palladium. The helium bubbles are treated via an expanding repulsive spherical potential within the metal lattice. The simulations predict bubble pressures that decrease monotonically with increasing helium to metal ratios. The swelling of the material associated with the bubble growth is also computed. It is found that the rate of swelling increases with increasing helium to metal ratio consistent with experimental observations on the swelling of metal tritides. Finally, the detailed defect structure due to the bubble growth was investigated. Dislocation networks are observed to form that connect the bubbles. Unlike early model assumptions, prismatic loops between the bubbles are not retained. These predictions are compared to available experimental evidence.
This suggested practices manual examines the requirements of the National Electrical Code (NEC) as they apply to photovoltaic (PV) power systems. The design requirements for the balance of systems components in a PV system are addressed, including conductor selection and sizing, overcurrent protection ratings and location, and disconnect ratings and location. PV array, battery, charge controller, and inverter sizing and selection are not covered, as these items are the responsibility of the system designer, and they in turn determine the items in this manual. Stand-alone, hybrid, and utility-interactive PV systems are all covered.
Current copper backplane technology has reached the technical limits of clock speed and width for systems requiring multiple boards. Currently, bus technology such as VME and PCI (types of buses) will face severe limitations are the bus speed approaches 100 MHz. At this speed, the physical length limit of an unterminated bus is barely three inches. Terminating the bus enables much higher clock rates but at drastically higher power cost. Sandia has developed high bandwidth parallel optical interconnects that can provide over 40 Gbps throughput between circuit boards in a system. Based on Sandia's unique VCSEL (Vertical Cavity Surface Emitting Laser) technology, these devices are compatible with CMOS (Complementary Metal Oxide Semiconductor) chips and have single channel bandwidth in excess of 20 GHz. In this project, we are researching the use of this interconnect scheme as the physical layer of a greater ATM (Asynchronous Transfer Mode) based backplane. There are several advantages to this technology including small board space, lower power and non-contact communication. This technology is also easily expandable to meet future bandwidth requirements in excess of 160 Gbps sometimes referred to as UTOPIA 6. ATM over optical backplane will enable automatic switching of wide high-speed circuits between boards in a system. In the first year we developed integrated VCSELs and receivers, identified fiber ribbon based interconnect scheme and a high level architecture. In the second year, we implemented the physical layer in the form of a PCI computer peripheral card. A description of future work including super computer networking deployment and protocol processing is included.
Surface and groundwater resources do not recognize political boundaries. Where nature and boundary cross, tension over shared water resources can erupt. Such tension is exacerbated in regions where demand approaches or exceeds sustainable supplies of water. Establishing equitable management strategies can help prevent and resolve conflict over shared water resources. This paper describes a methodology for addressing transboundary water issues predicated on the integration of monitoring and modeling within a framework of cooperation. Cooperative monitoring begins with agreement by international scientists and/or policy makers on transboundary monitoring goals and strategies; it leads to the process of obtaining and sharing agreed-upon information among parties with the purpose of providing verifiable and secure data. Cooperative modeling is the process by which the parties jointly interpret the data, forecast future events and trends, and quantify cause and effect relationships. Together, cooperative monitoring and modeling allow for the development and assessment of alternative management and remediation strategies that could form the basis of regional watershed agreements or treaties. An example of how this multifaceted approach might be used to manage a shared water resource is presented for the Kura River basin in the Caucasus.