Laser beam welding is the principal welding process for the joining of Sandia weapon components because it can provide a small fusion zone with low overall heating. Improved process robustness is desired since laser energy absorption is extremely sensitive to joint variation and filler metal is seldom added. This project investigated the experimental and theoretical advantages of combining a fiber optic delivered Nd:YAG laser with a miniaturized GMAW system. Consistent gas metal arc droplet transfer employing a 0.25 mm diameter wire was only obtained at high currents in the spray transfer mode. Excessive heating of the workpiece in this mode was considered an impractical result for most Sandia micro-welding applications. Several additional droplet detachment approaches were investigated and analyzed including pulsed tungsten arc transfer(droplet welding), servo accelerated transfer, servo dip transfer, and electromechanically braked transfer. Experimental observations and rigorous analysis of these approaches indicate that decoupling droplet detachment from the arc melting process is warranted and may someday be practical.
The Solar Thermal Program at Sandia supports work developing dish/Stirling systems to convert solar energy into electricity. Heat pipe technology is ideal for transferring the energy of concentrated sunlight from the parabolic dish concentrators to the Stirling engine heat tubes. Heat pipes can absorb the solar energy at non-uniform flux distributions and release this energy to the Stirling engine heater tubes at a very uniform flux distribution thus decoupling the design of the engine heater head from the solar absorber. The most important part of a heat pipe is the wick, which transports the sodium over the heated surface area. Bench scale heat pipes were designed and built to more economically, both in time and money, test different wicks and cleaning procedures. This report covers the building, testing, and post-test analysis of the sixth in a series of bench scale heat pipes. Durability heat pipe No.6 was built and tested to determine the effects of a high temperature bakeout, 950 C, on wick corrosion during long-term operation. Previous tests showed high levels of corrosion with low temperature bakeouts (650-700 C). Durability heat pipe No.5 had a high temperature bakeout and reflux cleaning and showed low levels of wick corrosion after long-term operation. After testing durability heat pipe No.6 for 5,003 hours at an operating temperature of 750 C, it showed low levels of wick corrosion. This test shows a high temperature bakeout alone will significantly reduce wick corrosion without the need for costly and time consuming reflux cleaning.
This report presents the major findings of the Montana State University Composite Materials Fatigue Program from 1997 to 2001, and is intended to be used in conjunction with the DOE/MSU Composite Materials Fatigue Database. Additions of greatest interest to the database in this time period include environmental and time under load effects for various resin systems; large tow carbon fiber laminates and glass/carbon hybrids; new reinforcement architectures varying from large strands to prepreg with well-dispersed fibers; spectrum loading and cumulative damage laws; giga-cycle testing of strands; tough resins for improved structural integrity; static and fatigue data for interply delamination; and design knockdown factors due to flaws and structural details as well as time under load and environmental conditions. The origins of a transition to increased tensile fatigue sensitivity with increasing fiber content are explored in detail for typical stranded reinforcing fabrics. The second focus of the report is on structural details which are prone to delamination failure, including ply terminations, skin-stiffener intersections, and sandwich panel terminations. Finite element based methodologies for predicting delamination initiation and growth in structural details are developed and validated, and simplified design recommendations are presented.
This report describes research and development of the large eddy simulation (LES) turbulence modeling approach conducted as part of Sandia's laboratory directed research and development (LDRD) program. The emphasis of the work described here has been toward developing the capability to perform accurate and computationally affordable LES calculations of engineering problems using unstructured-grid codes, in wall-bounded geometries and for problems with coupled physics. Specific contributions documented here include (1) the implementation and testing of LES models in Sandia codes, including tests of a new conserved scalar--laminar flamelet SGS combustion model that does not assume statistical independence between the mixture fraction and the scalar dissipation rate, (2) the development and testing of statistical analysis and visualization utility software developed for Exodus II unstructured grid LES, and (3) the development and testing of a novel new LES near-wall subgrid model based on the one-dimensional Turbulence (ODT) model.
This report summarizes progress from the Laboratory Directed Research and Development (LDRD) program during fiscal year 2001. In addition to a programmatic and financial overview, the report includes progress reports from 295 individual R and D projects in 14 categories.
To identify connections between technology needs for countering terrorism and underlying science issues and to recommend investment strategies to increase the impact of basic research on efforts to counter terrorism.
We have used a nonionic inverse micelle synthesis technique to form nanoclusters of platinum and palladium. These nanoclusters can be rendered hydrophobic or hydrophilic by the appropriate choice of capping ligand. Unlike Au nanoclusters, Pt nanoclusters show great stability with thiol ligands in aqueous media. Alkane thiols, with alkane chains ranging from C6 to C18, were used as hydrophobic ligands, and with some of these we were able to form two-dimensional and/or three-dimensional superlattices of Pt nanoclusters as small as 2.7 nm in diameter. Image processing techniques were developed to reliably extract from transmission electron micrographs (TEMs) the particle size distribution, and information about the superlattice domains and their boundaries. The latter permits us to compute the intradomain vector pair correlation function of the particle centers, from which we can accurately determine the lattice spacing and the coherent domain size. From these data the gap between the particles in the coherent domains can be determined as a function of the thiol chain length. It is found that as the thiol chain length increases, the interparticle gaps increase more slowly than the measured hydrodynamic radius of the functionalized nanoclusters in solution, possibly indicating thiol chain interdigitation in the superlattices.
The oxidation behavior of nickel-matrix/aluminum-particle composite coatings was studied using thermogravimetric (TG) analysis and long-term furnace exposure in air at 1000°C. The coatings were applied by the composite-electrodeposition technique and vacuum heat treated for 3 hr at 825°C prior to oxidation testing. The heat-treated coatings consisted of a two-phase mixture of γ (Ni) + γ′(Ni3Al). During short-term exposure at 1000°C, a thin α-Al2O3 layer developed below a matrix of spinel NiAl2O4, with θ-Al2O3 needles at the outer oxide surface. After 100 hr of oxidation, remnants of θ-Al2O3 are present with spinel at the surface and an inner layer of θ-Al2O3. After 1000-2000 hr, a relatively thick layer of α-Al2O3 is found below a thin, outer spinel layer. Oxidation kinetics are controlled by the slow growth of the inner Al2O3 layer at short-term and intermediate exposures. At long times, an increase in mass gain is found due to oxidation at the coating-substrate interface and enhanced scale formation possibly in areas of reduced Al content. Ternary Si additions to Ni-Al composite coatings were found to have little effect on oxidation performance. Comparison of coatings with bulk Ni-Al alloys showed that low Al γ-alloys exhibit a healing Al2O3 layer after transient Ni-rich oxide growth. Higher Al alloys display Al2O3-controlled kinetics with low mass gain during TG analysis.
Laser safety evaluation and output emission measurements were performed (during October and November 2001) on SNL MILES and Mini MILES laser emitting components. The purpose, to verify that these components, not only meet the Class 1 (eye safe) laser hazard criteria of the CDRH Compliance Guide for Laser Products and 21 CFR 1040 Laser Product Performance Standard; but also meet the more stringent ANSI Std. z136.1-2000 Safe Use of Lasers conditions for Class 1 lasers that govern SNL laser operations. The results of these measurements confirmed that all of the Small Arms Laser Transmitters, as currently set (''as is''), meet the Class 1 criteria. Several of the Mini MILES Small Arms Transmitters did not. These were modified and re-tested and now meet the Class 1 laser hazard criteria. All but one System Controllers (hand held and rifle stock) met class 1 criteria for single trigger pulls and all presented Class 3a laser hazard levels if the trigger is held (continuous emission) for more than 5 seconds on a single point target. All units were Class 3a for ''aided'' viewing. These units were modified and re-tested and now meet the Class 1 hazard criteria for both ''aided'' as well as ''unaided'' viewing. All the Claymore Mine laser emitters tested are laser hazard Class 1 for both ''aided'' as well as ''unaided'' viewing.
The use of biometrics for the identification of individuals is becoming more prevalent in society and in the general government community. As the demand for these devices increases, it becomes necessary for the user community to have the facts needed to determine which device is the most appropriate for any given application. One such application is the use of biometric devices in areas where an individual may not be able to present a biometric feature that requires contact with the identifier (e.g., when dressed in anti-contamination suits or when wearing a respirator). This paper discusses a performance evaluation conducted on the IrisScan2200 from Iridian Technologies to determine if it could be used in such a role.
The theory, numerical algorithm, and user documentation are provided for a new ''Centroidal Voronoi Tessellation (CVT)'' method of filling a region of space (2D or 3D) with particles at any desired particle density. ''Clumping'' is entirely avoided and the boundary is optimally resolved. This particle placement capability is needed for any so-called ''mesh-free'' method in which physical fields are discretized via arbitrary-connectivity discrete points. CVT exploits efficient statistical methods to avoid expensive generation of Voronoi diagrams. Nevertheless, if a CVT particle's Voronoi cell were to be explicitly computed, then it would have a centroid that coincides with the particle itself and a minimized rotational moment. The CVT code provides each particle's volume and centroid, and also the rotational moment matrix needed to approximate a particle by an ellipsoid (instead of a simple sphere). DIATOM region specification is supported.
This report describes the results of a Laboratory-Directed Research and Development project on techniques for pattern discovery in discrete event time series data. In this project, we explored two different aspects of the pattern matching/discovery problem. The first aspect studied was the use of Dynamic Time Warping for pattern matching in continuous data. In essence, DTW is a technique for aligning time series along the time axis to optimize the similarity measure. The second aspect studied was techniques for discovering patterns in discrete event data. We developed a pattern discovery tool based on adaptations of the A-priori and GSP (Generalized Sequential Pattern mining) algorithms. We then used the tool on three different application areas--unattended monitoring system data from a storage magazine, computer network intrusion detection, and analysis of robot training data.
The requirements in modeling and simulation are driven by two fundamental changes in the nuclear weapons landscape: (1) The Comprehensive Test Ban Treaty and (2) The Stockpile Life Extension Program which extends weapon lifetimes well beyond their originally anticipated field lifetimes. The move from confidence based on nuclear testing to confidence based on predictive simulation forces a profound change in the performance asked of codes. The scope of this document is to improve the confidence in the computational results by demonstration and documentation of the predictive capability of electrical circuit codes and the underlying conceptual, mathematical and numerical models as applied to a specific stockpile driver. This document describes the High Performance Electrical Modeling and Simulation software normal environment Verification and Validation Plan.
FAILPROB is a computer program that applies the Weibull statistics characteristic of brittle failure of a material along with the stress field resulting from a finite element analysis to determine the probability of failure of a component. FAILPROB uses the statistical techniques for fast fracture prediction (but not the coding) from the N.A.S.A. - CARES/life ceramic reliability package. FAILPROB provides the analyst at Sandia with a more convenient tool than CARES/life because it is designed to behave in the tradition of structural analysis post-processing software such as ALGEBRA, in which the standard finite element database format EXODUS II is both read and written. This maintains compatibility with the entire SEACAS suite of post-processing software. A new technique to deal with the high local stresses computed for structures with singularities such as glass-to-metal seals and ceramic-to-metal braze joints is proposed and implemented. This technique provides failure probability computation that is insensitive to the finite element mesh employed in the underlying stress analysis. Included in this report are a brief discussion of the computational algorithms employed, user instructions, and example problems that both demonstrate the operation of FAILPROB and provide a starting point for verification and validation.
This report documents the strategies for verification and validation of the codes LSP and ICARUS used for simulating the operation of the neutron tubes used in all modern nuclear weapons. The codes will be used to assist in the design of next generation neutron generators and help resolve manufacturing issues for current and future production of neutron devices. Customers for the software are identified, tube phenomena are identified and ranked, software quality strategies are given, and the validation plan is set forth.
The theory and algorithm for the Material Point Method (MPM) are documented, with a detailed discussion on the treatments of boundary conditions and shock wave problems. A step-by-step solution scheme is written based on direct inspection of the two-dimensional MPM code currently used at the University of Missouri-Columbia (which is, in turn, a legacy of the University of New Mexico code). To test the completeness of the solution scheme and to demonstrate certain features of the MPM, a one-dimensional MPM code is programmed to solve one-dimensional wave and impact problems, with both linear elasticity and elastoplasticity models. The advantages and disadvantages of the MPM are investigated as compared with competing mesh-free methods. Based on the current work, future research directions are discussed to better simulate complex physical problems such as impact/contact, localization, crack propagation, penetration, perforation, fragmentation, and interactions among different material phases. In particular, the potential use of a boundary layer to enforce the traction boundary conditions is discussed within the framework of the MPM.
Nuclear energy has been proposed as a heat source for producing hydrogen from water using a sulfur-iodine thermochemical cycle. This document presents an assessment of the suitability of various reactor types for this application. The basic requirement for the reactor is the delivery of 900 C heat to a process interface heat exchanger. Ideally, the reactor heat source should not in itself present any significant design, safety, operational, or economic issues. This study found that Pressurized and Boiling Water Reactors, Organic-Cooled Reactors, and Gas-Core Reactors were unsuitable for the intended application. Although Alkali Metal-Cooled and Liquid-Core Reactors are possible candidates, they present significant development risks for the required conditions. Heavy Metal-Cooled Reactors and Molten Salt-Cooled Reactors have the potential to meet requirements, however, the cost and time required for their development may be appreciable. Gas-Cooled Reactors (GCRs) have been successfully operated in the required 900 C coolant temperature range, and do not present any obvious design, safety, operational, or economic issues. Altogether, the GCRs approach appears to be very well suited as a heat source for the intended application, and no major development work is identified. This study recommends using the Gas-Cooled Reactor as the baseline reactor concept for a sulfur-iodine cycle for hydrogen generation.
The blast parameters for the 6-foot diameter by 200-foot long, explosively driven shock tube are presented in this report. The purpose, main characteristics, and blast simulation capabilities of this PETN Primacord, explosively driven facility are included. Experimental data are presented for air and Sulfurhexaflouride (SF6) test gases with initial pressures between 0.5 to 12.1 psia (ambient). Experimental data are presented and include shock wave time of amval at various test stations, flow duration, static or side-on overpressure, and stagnation or head-on overpressure. The blast parameters calculated from the above measured parameters and presented in this report include shock wave velocity, shock strength, shock Mach number, flow Mach Number, reflected pressure, dynamic pressure, particle velocity, density, and temperature. Graphical data for the above parameters are included. Algorithms and least squares fit equations are also included.
The assembly and packaging of MEMS (Microelectromechanical Systems) devices raise a number of issues over and above those normally associated with the assembly of standard microelectronic circuits. MEMS components include a variety of sensors, microengines, optical components, and other devices. They often have exposed mechanical structures which during assembly require particulate control, free space in the package, non-contact handling procedures, low-stress die attach, precision die placement, unique process schedules, hermetic sealing in controlled environments (including vacuum), and other special constraints. These constraints force changes in the techniques used to separate die on a wafer, in the types of packages which can be used, in the assembly processes and materials, and in the sealing environment and process. This paper discusses a number of these issues and provides information on approaches being taken or proposed to address them.
The Geothermal Research Dept. at Sandia Natl. Laboratories, in collaboration with Drill Cool Systems Inc., has worked to develop and test insulated drillpipe (IDP). IDP will allow much cooler drilling fluid to reach the bottom of the hole, making possible the use of downhole motors, electronics, and steering tools that are now useless in high-temperature formations. Other advantages of cooler fluid include reduced degradation of drilling fluid, longer bit life, and reduced corrosion rates. This article describes the theoretical background, laboratory testing, and field testing of IDP, including structural and thermal laboratory testing procedures and results. We also give results for a field test in a geothermal well in which circulating temperatures in IDP are compared with those in conventional drillpipe (CDP) at different flow rates. A brief description of the software used to model wellbore temperature and to calculate sensitivity in IDP design differences is included, along with a comparison of calculated and measured wellbore temperatures in the field test. There is also analysis of mixed (IDP and CDP) drillstrings and discussion of where IDP should be placed in a mixed string.
A study was performed on the Sandia Heat Flux Gauge (HFG) developed as a rugged, cost effective technique for performing steady state heat flux measurements in the pool fire environment. The technique involved reducing the time-temperature history of a thin metal plate to an incident heat flux via a dynamic thermal model, even though the gauge was intended for use at steady state. A validation experiment was presented where the gauge was exposed to a step input of radiant heat flux.
We consider the steady-state transport of normally incident pencil beams of radiation in slabs of material. A method has been developed for determining the exact radial moments of three-dimensional (3-D) beams of radiation as a function of depth into the slab, by solving systems of one-dimensional (1-D) transport equations. We implement these radial-moment equations in the ONEBFP discrete ordinates code and simulate energy-dependent, coupled electron-photon beams using CEPXS-generated cross sections. Modified PN synthetic acceleration is employed to speed up the iterative convergence of the 1-D charged-particle calculations. For high-energy photon beams, a hybrid Monte Carlo/discrete ordinates method is examined. We demonstrate the efficiency of the calculations and make comparisons with 3-D Monte Carlo calculations. Thus, by solving 1-D transport equations, we obtain realistic multidimensional information concerning the broadening of electron-photon beams. This information is relevant to fields such as industrial radiography, medical imaging, radiation oncology, particle accelerators, and lasers.
A family of transients with the property that the initial and final acceleration, velocity, and displacement are all zero is derived. The transients are based on a relatively arbitrary function multiplied by window of the form cosm(x). Several special cases are discussed which result in odd acceleration and displacement functions. This is desirable for shaker reproduction because the required positive and negative peak accelerations and displacements will be balanced. Another special case is discussed which will permit the development of transients with the first five (0-4) temporal moments specified. The transients are defined with three or four parameters that will allow sums of components to be found which will match a variety of shock response spectra.
The verification and validation (V & V) in computational fluid dynamics was presented. The methods and procedures for assessing V & V were presented. The issues such as code verification versus solution verification, model validation versus solution validation, the distinction between error and uncertainity, conceptual sources of error and uncertainity, and the relationship between validation and prediction was discussed. Methods for determining the accuracy of numerical solutions were presented and the importance of software testing during verification activities were emphasized.
The Computational Plant or Cplant is a commodity-based supercomputer under development at Sandia National Laboratories. This paper describes resource-allocation strategies to achieve processor locality for parallel jobs in Cplant and other supercomputers. Users of Cplant and other Sandia supercomputers submit parallel jobs to a job queue. When a job is scheduled to run, it is assigned to a set of processors. To obtain maximum throughput, jobs should be allocated to localized clusters of processors to minimize communication costs and to avoid bandwidth contention caused by overlapping jobs. This paper introduces new allocation strategies and performance metrics based on space-filling curves and one dimensional allocation strategies. These algorithms are general and simple. Preliminary simulations and Cplant experiments indicate that both space-filling curves and one-dimensional packing improve processor locality compared to the sorted free list strategy previously used on Cplant. These new allocation strategies are implemented in the new release of the Cplant System Software, Version 2.0, phased into the Cplant systems at Sandia by May 2002.
The ABO3 perovskite oxides constitute an important family of technologically important ferroelectrics whose relatively simple chemical and crystallographic structures have contributed significantly to our understanding of ferroelectricity. They readily undergo structural phase transitions involving both polar and non-polar distortions from the ideal cubic lattice. This paper focuses on the mixed perovskite system KTa1-xNbxO3, or KTN, which has turned out to be a model system. While the end members KTaO3 and KNbO3 might be expected to be similar, in reality they exhibit very different properties. Their mixed crystals, which can be grown over the whole composition range, exhibit a rich set of phenomena whose study has added greatly to our current understanding of the phase trsitions and dielectric properties of these materials. Included among these phenomena are soft mode response, ferroelectric (FE)-to-relaxor (R) crossover, quantum mechanical suppression of the transition, the appearance of a quantum paraelectric state and relaxational effects associated with dipolar impurities. Each of these phenomena is discussed briefly and illustrated. Some emphasis is on the unique role of pressure in elucidating the physics involved.
We consider two fundamental problems in dynamic scheduling: scheduling to meet deadlines in a preemptive multiprocessor setting, and scheduling to provide good response time in a number of scheduling environments. When viewed from the perspective of traditional worst-case analysis, no good on-line algorithms exist for these problems, and for some variants no good off-line algorithms exist unless T = NP. We study these problems using a relaxed notion of competitive analysis, introduced by Kalyanasundaram and Pruhs, in which the on-line algorithm is allowed more resources than the optimal off-line algorithm to which it is compared. Using this approach, we establish that several well-known on-line algorithms, that have poor performance from an absolute worst-case perspective, are optimal for the problems in question when allowed moderately more resources. For optimization of average flow time, these are the first results of any sort, for any NP-hard version of the problem, that indicate that it might be possible to design good approximation algorithms.
One of the concerns surrounding composite doubler technology pertains to long-term survivability, especially in the presence of non-optimum installations. This test program demonstrated the damage-tolerance capabilities of bonded composite doublers. The fatigue and strength tests quantified the structural response and crack-abatement capabilities of boron-epoxy doublers in the presence of worst-case flaw scenarios. The engineered flaws included cracks in the parent material, disbonds in the adhesive layer, and impact damage to the composite laminate. Environmental conditions representing temperature and humidity exposure were also included in the coupon tests. Large strains immediately adjacent to the doubler flaws emphasize the fact that relatively large disbond or delamination flaws (up to 100 diameter) in the composite doubler have only localized effects on strain and minimal effect on the overall doubler performance (i.e., undesirable strain relief over disbond but favorable load transfer immediately next to disbond). This statement is made relative to the inspection requirement that result in the detection of disbonds/delaminations of 0.5 '' diameter or greater. The point at which disbonds become detrimental depends upon the size and location of the disbond and the strain field around the doubler. This study did not attempt to determine a "flaw size vs. effect" relation. Rather, it used flaws that were twice as large as the detectable limit to demonstrate the ability of composite doublers to tolerate potential damage.
Two major issues associated with model validation are addressed here. First, we present a maximum likelihood approach to define and evaluate a model validation metric. The advantage of this approach is it is more easily applied to nonlinear problems than the methods presented earlier by Hills and Trucano (1999, 2001); the method is based on optimization for which software packages are readily available; and the method can more easily be extended to handle measurement uncertainty and prediction uncertainty with different probability structures. Several examples are presented utilizing this metric. We show conditions under which this approach reduces to the approach developed previously by Hills and Trucano (2001). Secondly, we expand our earlier discussions (Hills and Trucano, 1999, 2001) on the impact of multivariate correlation and the effect of this on model validation metrics. We show that ignoring correlation in multivariate data can lead to misleading results, such as rejecting a good model when sufficient evidence to do so is not available.
Collaboration between Sandia National Laboratories and the University of New Mexico Biology Department resulted in the capability to train students in microarray techniques and the interpretation of data from microarray experiments. These studies provide for a better understanding of the role of stationary phase and the gene regulation involved in exit from stationary phase, which may eventually have important clinical implications. Importantly, this research trained numerous students and is the basis for three new Ph.D. projects.
Hyperspectral Fourier transform infrared images have been obtained from a neoprene sample aged in air at elevated temperatures. The massive amount of spectra available from this heterogeneous sample provides the opportunity to perform quantitative analysis of the spectral data without the need for calibration standards. Multivariate curve resolution (MCR) methods with non-negativity constraints applied to the iterative alternating least squares analysis of the spectral data has been shown to achieve the goal of quantitative image analysis without the use of standards. However, the pure-component spectra and the relative concentration maps were heavily contaminated by the presence of system artifacts in the spectral data. We have demonstrated that the detrimental effects of these artifacts can be minimized by adding an estimate of the error covariance structure of the spectral image data to the MCR algorithm. The estimate is added by augmenting the concentration and pure-component spectra matrices with scores and eigenvectors obtained from the mean-centered repeat image differences of the sample. The implementation of augmentation is accomplished by employing efficient equality constraints on the MCR analysis. Augmentation with the scores from the repeat images is found to primarily improve the pure-component spectral estimates while augmentation with the corresponding eigenvectors primarily improves the concentration maps. Augmentation with both scores and eigenvectors yielded the best result by generating less noisy pure-component spectral estimates and relative concentration maps that were largely free from a striping artifact that is present due to system errors in the FT-IR images. The MCR methods presented are general and can also be applied productively to non-image spectral data.
One of the major needs of the law enforcement field is a product that quickly, accurately, and inexpensively identifies whether a person has recently fired a gun--even if the suspect has attempted to wash the traces of gunpowder off. The Field Test Kit for Gunshot Residue Identification based on Sandia National Laboratories technology works with a wide variety of handguns and other weaponry using gunpowder. There are several organic chemicals in small arms propellants such as nitrocellulose, nitroglycerine, dinitrotoluene, and nitrites left behind after the firing of a gun that result from the incomplete combustion of the gunpowder. Sandia has developed a colorimetric shooter identification kit for in situ detection of gunshot residue (GSR) from a suspect. The test kit is the first of its kind and is small, inexpensive, and easily transported by individual law enforcement personnel requiring minimal training for effective use. It will provide immediate information identifying gunshot residue.
The Nonactinide Isotopes and Sealed Sources (NISS) Web Application is a web-based database query and data management tool designed to facilitate the identification and reapplication of radioactive sources throughout the Department of Energy (DOE) complex. It provides search capability to the general Internet community and detailed data management functions to contributing site administrators.
The present document summarizes the experimental efforts of a three-year study funded under the Laboratory Directed Research and Development program of Sandia National Laboratories. The Innovative Diagnostics LDRD project was designed to develop new measurement capabilities to examine the interaction of a propulsive spin jet in a transonic freestream for a model in a wind tunnel. The project motivation was the type of jet/fin interactions commonly occurring during deployment of weapon systems. In particular, the two phenomena of interest were the interaction of the propulsive spin jet with the freestream in the vicinity of the nozzle and the impact of the spin rocket plume and its vortices on the downstream fins. The main thrust of the technical developments was to incorporate small-size, Lagrangian sensors for pressure and roll-rate on a scale model and include data acquisition, transmission, and power circuitry onboard. FY01 was the final year of the three-year LDRD project and the team accomplished much of the project goals including use of micron-scale pressure sensors, an onboard telemetry system for data acquisition and transfer, onboard jet exhaust, and roll-rate measurements. A new wind tunnel model was designed, fabricated, and tested for the program which incorporated the ability to house multiple MEMS-based pressure sensors, interchangeable vehicle fins with pressure instrumentation, an onboard multiple-channel telemetry data package, and a high-pressure jet exhaust simulating a spin rocket motor plume. Experiments were conducted for a variety of MEMS-based pressure sensors to determine performance and sensitivity in order to select pressure transducers for use. The data acquisition and analysis path was most successful by using multiple, 16-channel data processors with telemetry capability to a receiver outside the wind tunnel. The development of the various instrumentation paths led to the fabrication and installation of a new wind tunnel model for baseline non-rotating experiments to validate the durability of the technologies and techniques. The program successfully investigated a wide variety of instrumentation and experimental techniques and ended with basic experiments for a non-rotating model with jet-on with the onboard jets operating and both rotating and non-rotating model conditions.
This report summarizes a multiyear effort to establish a new capability for determining dynamic material properties. By utilizing a significant reduction in experimental length and time scales, this new capability addresses both the high per-experiment costs of current methods and the inability of these methods to characterize materials having very small dimensions. Possible applications include bulk-processed materials with minimal dimensions, very scarce or hazardous materials, and materials that can only be made with microscale dimensions. Based on earlier work to develop laser-based techniques for detonating explosives, the current study examined the laser acceleration, or photonic driving, of small metal discs (''flyers'') that can generate controlled, planar shockwaves in test materials upon impact. Sub-nanosecond interferometric diagnostics were developed previously to examine the motion and impact of laser-driven flyers. To address a broad range of materials and stress states, photonic driving levels must be scaled up considerably from the levels used in earlier studies. Higher driving levels, however, increase concerns over laser-induced damage in optics and excessive heating of laser-accelerated materials. Sufficiently high levels require custom beam-shaping optics to ensure planar acceleration of flyers. The present study involved the development and evaluation of photonic driving systems at two driving levels, numerical simulations of flyer acceleration and impact using the CTH hydrodynamics code, design and fabrication of launch assemblies, improvements in diagnostic instrumentation, and validation experiments on both bulk and thin-film materials having well-established shock properties. The primary conclusion is that photonic driving techniques are viable additions to the methods currently used to obtain dynamic material properties. Improvements in launch conditions and diagnostics can certainly be made, but the main challenge to future applications will be the successful design and fabrication of test assemblies for materials of interest.
SERAPHIM technology appears capable of efficiently driving a tip driven fan. If the motor is powered using an inverter and resonant circuit, the size and weight could be considerably below that of a comparable rotary electric motor.
Recyclable transmission lines (RTL) are studied as a means of repetitively driving z pinches. The lowest reprocessing costs should be obtained by minimizing the mass of the RTL. Low mass transmission lines (LMTL) could also help reduce the cost of a single shot facility such as the proposed X-1 accelerator and make z-pinch driven space propulsion feasible. We present calculations to determine the minimum LMTL electrode mass to provide sufficient inertia against the magnetic pressure produced by the large currents needed to drive the z pinches. The results indicate an electrode thickness which is much smaller than the resistive skin depth. We have performed experiments to determine if such thin electrodes can efficiently carry the required current. The tests were performed with various thickness of materials. The results indicate that LMTLs should efficiently carry the large z-pinch currents needed for inertial fusion. We also use our results to estimate of the performance of pulsed power driven pulsed nuclear rockets.
High-brightness flash x-ray sources are needed for penetrating dynamic radiography for a variety of applications. Various bremsstrahlung source experiments have been conducted on the TriMeV accelerator (3MV, 60 {Omega}, 20 ns) to determine the best diode and focusing configuration in the 2-3 MV range. Three classes of candidate diodes were examined: gas cell focusing, magnetically immersed, and rod pinch. The best result for the gas cell diode was 6 rad at 1 meter from the source with a 5 mm diameter x-ray spot. Using a 0.5 mm diameter cathode immersed in a 17 T solenoidal magnetic field, the best shot produced 4.1 rad with a 2.9 mm spot. The rod pinch diode demonstrated very reproducible radiographic spots between 0.75 and 0.8 mm in diameter, producing 1.2 rad. This represents a factor of eight improvement in the TriMeV flash radiographic capability above the original gas cell diode to a figure of merit (dose/spot diameter) > 1.8 rad/mm. These results clearly show the rod pinch diode to be the choice x-ray source for flash radiography at 2-3 M V endpoint.
This report describes the development of bulk hydrous titanium oxide (HTO)- and silica-doped hydrous titanium oxide (HTO:Si)-supported Pt catalysts for lean-burn NOx catalyst applications. The effects of various preparation methods, including both anion and cation exchange, and specifically the effect of Na content on the performance of Pt/HTO:Si catalysts, were evaluated. Pt/HTO:Si catalysts with low Na content (< 0.5 wt.%) were found to be very active for NOx reduction in simulated lean-burn exhaust environments utilizing propylene as the major reductant species. The activity and performance of these low Na Pt/HTO:Si catalysts were comparable to supported Pt catalysts prepared using conventional oxide or zeolite supports. In ramp down temperature profile test conditions, Pt/HTO:Si catalysts with Na contents in the range of 3-5 wt.% showed a wide temperature window of appreciable NOx conversion relative to low Na Pt/HTO:Si catalysts. Full reactant species analysis using both ramp up and isothermal test conditions with the high Na Pt/HTO:Si catalysts, as well as diffuse reflectance FTIR studies, showed that this phenomenon was related to transient NOx storage effects associated with NaNO{sub 2}/NaNO{sub 3} formation. These nitrite/nitrate species were found to decompose and release NOx at temperatures above 300 C in the reaction environment (ramp up profile). A separate NOx uptake experiment at 275 C in NO/N{sub 2}/O{sub 2} showed that the Na phase was inefficiently utilized for NOx storage. Steady state tests showed that the effect of increased Na content was to delay NOx light-off and to decrease the maximum NOx conversion. Similar results were observed for high K Pt/HTO:Si catalysts, and the effects of high alkali content were found to be independent of the sample preparation technique. Catalyst characterization (BET surface area, H{sub 2} chemisorption, and transmission electron microscopy) was performed to elucidate differences between the HTO- and HTO:Si-supported Pt catalysts and conventional oxide- or zeolite-supported Pt catalysts.
Sandia National Laboratories has previously developed a unidirectional High Shear Stress Sediment Erosion flume for the US Army Corps of Engineers, Coastal Hydraulics Laboratory. The flow regime for this flume has limited applicability to wave-dominated environments. A significant design modification to the existing flume allows oscillatory flow to be superimposed upon a unidirectional current. The new flume simulates highshear stress erosion processes experienced in coastal waters where wave forcing dominates the system. Flow velocity measurements, and erosion experiments with known sediment samples were performed with the new flume. Also, preliminary computational flow models closely simulate experimental results and allow for a detailed assessment of the induced shear stresses at the sediment surface.
The Department of Energy (DOE) is moving towards Long-Term Stewardship (LTS) of many environmental restoration sites that cannot be released for unrestricted use. One aspect of information management for LTS is geospatial data archiving. This report discusses the challenges facing the DOE LTS program concerning the data management and archiving of geospatial data. It discusses challenges in using electronic media for archiving, overcoming technological obsolescence, data refreshing, data migration, and emulation. It gives an overview of existing guidance and policy and discusses what the United States Geological Service (USGS), National Oceanic and Atmospheric Administration (NOAA) and the Federal Emergency Management Agency (FEMA) are doing to archive the geospatial data that their agencies are responsible for. In the conclusion, this report provides issues for further discussion around long-term spatial data archiving.
Solar Two was a collaborative, cost-shared project between 11 U. S. industry and utility partners and the U. S. Department of Energy to validate molten-salt power tower technology. The Solar Two plant, located east of Barstow, CA, comprised 1926 heliostats, a receiver, a thermal storage system, a steam generation system, and steam-turbine power block. Molten nitrate salt was used as the heat transfer fluid and storage media. The steam generator powered a 10-MWe (megawatt electric), conventional Rankine cycle turbine. Solar Two operated from June 1996 to April 1999. The major objective of the test and evaluation phase of the project was to validate the technical characteristics of a molten salt power tower. This report describes the significant results from the test and evaluation activities, the operating experience of each major system, and overall plant performance. Tests were conducted to measure the power output (MW) of the each major system, the efficiencies of the heliostat, receiver, thermal storage, and electric power generation systems and the daily energy collected, daily thermal-to-electric conversion, and daily parasitic energy consumption. Also included are detailed test and evaluation reports.
This document provides a guide to the deployment of the software verification activities, software engineering practices, and project management principles that guide the development of Accelerated Strategic Computing Initiative (ASCI) applications software at Sandia National Laboratories (Sandia). The goal of this document is to identify practices and activities that will foster the development of reliable and trusted products produced by the ASCI Applications program. Document contents include an explanation of the structure and purpose of the ASCI Quality Management Council, an overview of the software development lifecycle, an outline of the practices and activities that should be followed, and an assessment tool. These sections map practices and activities at Sandia to the ASCI Software Quality Engineering: Goals, Principles, and Guidelines, a Department of Energy document.
Water shortages affect 88 developing countries that are home to half of the world's population. In these places, 80-90% of all diseases and 30% of all deaths result from poor water quality. Furthermore, over the next 25 years, the number of people affected by severe water shortages is expected to increase fourfold. Low cost methods of purifying freshwater, and desalting seawater are required to contend with this destabilizing trend. Membrane distillation (MD) is an emerging technology for separations that are traditionally accomplished via conventional distillation or reverse osmosis. As applied to desalination, MD involves the transport of water vapor from a saline solution through the pores of a hydrophobic membrane. In sweeping gas MD, a flowing gas stream is used to flush the water vapor from the permeate side of the membrane, thereby maintaining the vapor pressure gradient necessary for mass transfer. Since liquid does not penetrate the hydrophobic membrane, dissolved ions are completely rejected by the membrane. MD has a number of potential advantages over conventional desalination including low temperature and pressure operation, reduced membrane strength requirements, compact size, and 100% rejection of non-volatiles. The present work evaluated the suitability of commercially available technology for sweeping gas membrane desalination. Evaluations were conducted with Celgard Liqui-Cel{reg_sign} Extra-Flow 2.5X8 membrane contactors with X-30 and X-40 hydrophobic hollow fiber membranes. Our results show that sweeping gas membrane desalination systems are capable of producing low total dissolved solids (TDS) water, typically 10 ppm or less, from seawater, using low grade heat. However, there are several barriers that currently prevent sweeping gas MD from being a viable desalination technology. The primary problem is that large air flows are required to achieve significant water yields, and the costs associated with transporting this air are prohibitive. To overcome this barrier, at least two improvements are required. First, new and different contactor geometries are necessary to achieve efficient contact with an extremely low pressure drop. Second, the temperature limits of the membranes must be increased. In the absence of these improvements, sweeping gas MD will not be economically competitive. However, the membranes may still find use in hybrid desalination systems.
The use of oxidized metal powders in mechanical shock or crush safety enhancers in nuclear weapons has been investigated. The functioning of these devices is based on the remarkable electrical behavior of compacts of certain oxidized metal powders when subjected to compressive stress. For example, the low voltage resistivity of a compact of oxidized tantalum powder was found to decrease by over six orders of magnitude during compaction between 1 MPa, where the thin, insulating oxide coatings on the particles are intact, to 10 MPa, where the oxide coatings have broken down along a chain of particles spanning the electrodes. In this work, the behavior of tantalum and aluminum powders was investigated. The low voltage resistivity during compaction of powders oxidized under various conditions was measured and compared. In addition, the resistivity at higher voltages and the dielectric breakdown strength during compaction were also measured. A key finding was that significant changes in the electrical properties persist after the removal of the stress so that a mechanical shock enhancer is feasible. This was verified by preliminary shock experiments. Finally, conceptual designs for both types of enhancers are presented.
Preliminary thermal decomposition experiments with Ablefoam and EF-AR20 foam (Ablefoam replacement) were done to determine the important chemical and associated physical phenomena that should be investigated to develop the foam decomposition chemistry sub-models that are required in numerical simulations of the fire-induced response of foam-filled engineered systems for nuclear safety applications. Although the two epoxy foams are physically and chemically similar, the thermal decomposition of each foam involves different chemical mechanisms, and the associated physical behavior of the foams, particularly ''foaming'' and ''liquefaction,'' have significant implications for modeling. A simplified decomposition chemistry sub-model is suggested that, subject to certain caveats, may be appropriate for ''scoping-type'' calculations.
This report is a presentation of modeling and simulation work for analyzing three designs of Micro Electro Mechanical (MEM) Compound Pivot Mirrors (CPM). These CPMs were made at Sandia National Laboratories using the SUMMiT{trademark} process. At 75 volts and above, initial experimental analysis of fabricated mirrors showed tilt angles of up to 7.5 degrees for one design, and 5 degrees for the other two. Nevertheless, geometric design models predicted higher tilt angles. Therefore, a detailed study was conducted to explain why lower tilt angles occurred and if design modifications could be made to produce higher tilt angles at lower voltages. This study showed that the spring stiffnesses of the CPMs were too great to allow for desired levels of rotation at lower levels of voltage. To produce these lower stiffnesses, a redesign is needed.
The semiconductor bridge (SCB) is an electroexplosive device used to initiate detonators. A C cable is commonly used to connect the SCB to a firing set. A series of tests were performed to identify smaller, lighter cables for firing single and multiple SCBs. This report provides a description of these tests and their results. It was demonstrated that lower threshold voltages and faster firing times can be achieved by increasing the wire size, which reduces ohmic losses. The RF 100 appears to be a reasonable substitute for C cable when firing single SCBs. This would reduce the cable volume by 68% and the weight by 67% while increasing the threshold voltage by only 22%. In general, RG 58 outperforms twisted pair when firing multiple SCBs in parallel. The RG 58's superior performance is attributed to its larger conductor size.
Chemometric analysis of nuclear magnetic resonance (NMR) spectroscopy has increased dramatically in recent years. Various chemometric techniques have been applied to a wide range of problems in food, agricultural, medical, process, and industrial system. This article gives a brief review of chemometric analysis of NMR spectral data, including a summary of the types of mixtures and experiments analyzed with chemometric techniques. Common experiment problems encountered during the chemometric analysis of NMR data are also discussed.
Stiction and friction in micromachines is commonly inhibited through the use of silane coupling agents such as 1H-, 1H-, 2H-, 2H-perfluorodecyltrichlorosilane (FDTS). FDTS coatings have allowed micromachine parts processed in water to be released without debilitating capillary adhesion occurring. These coatings are frequently considered as densely-packed monolayers, well-bonded to the substrate. In this paper, it is demonstrated that FDTS coatings can exhibit complex nanoscale structures, which control whether micromachine parts release or not. Surface images obtained via atomic force microscopy reveal that FDTS coating solutions can generate micellar aggregates that deposit on substrate surfaces. Interferometric imaging of model beam structures shows that stiction is high when the droplets are present and low when only monolayers are deposited. As the aggregate thickness (tens of nanometers) is insufficient to bridge the 2 μm gap under the beams, the aggregates appear to promote beam-substrate adhesion by changing the wetting characteristics of coated surfaces. Contact angle measurements and condensation figure experiments have been performed on surfaces and under coated beams to quantify the changes in interfacial properties that accompany different coating structures. These results may explain the irreproducibility that is often observed with these films.
A DOE/Sandia project termed the Blade Manufacturing Program was established at Sandia to develop means of advancing manufacturing processes in ways that lower costs and improve the reliability of turbine blades. Through industry contracts, manufacturers are improving processes such as resin infusion, resin transfer molding, and thermoplastic casting. Testing and modeling research at universities and national labs are adding to the knowledge of how composite materials perform in substructures and sub-scale blades as a function of their fabrication process.
Optimal estimation theory has been applied to the problem of estimating process variables during vacuum arc remelting (VAR), a process widely used in the specialty metals industry to cast large ingots of segregation sensitive and/or reactive metal alloys. Four state variables were used to develop a simple state-space model of the VAR process: electrode gap (G), electrode mass (M), electrode position (X) and electrode melting rate (R). The optimal estimator consists of a Kalman filter that incorporates the model and uses electrode feed rate and measurement based estimates of G, M and X to produce optimal estimates of all four state variables. Simulations show that the filter provides estimates that have error variances between one and three orders-of-magnitude less than estimates based solely on measurements. Examples are presented that verify this for electrode gap, an extremely important control parameter for the process.
Direct Simulation Monte Carlo (DSMC) and Navier-Stokes calculations are performed for a Mach 11 25 deg.-55 deg. spherically blunted biconic. The conditions are such that flow is laminar, with separation occurring at the cone-cone juncture. The simulations account for thermochemical nonequilibrium based on standard Arrhenius chemical rates for nitrogen dissociation and Millikan and White vibrational relaxation. The simulation error for the Navier-Stokes (NS) code is estimated to be 2% for the surface pressure and 10% for the surface heat flux. The grid spacing for the DSMC simulations was adjusted to be less than the local mean-freepath (mfp) and the time step less than the cell transient time of a computational particle. There was overall good agreement between the two simulations; however, the recirculation zone was computed to be larger for the NS simulation. A sensitivity study is performed to examine the effects of experimental uncertainty in the freestream properties on the surface pressure and heat flux distributions. The surface quantities are found to be extremely sensitive to the vibrational excitation state of the gas at the test section, with differences of 25% found in the surface pressure and 25%-35% for the surface heat flux. These calculations are part of a blind validation comparison and thus the experimental data has not yet been released.
Simulations of a turbulent methanol pool fire are conducted using both Reynolds-Averaged Navier-Stokes (RANS) and Large Eddy Simulation (LES) modeling methodologies. Two simple conserved scalar flameletbased combustion models with assumed PDF are developed and implemented. The first model assumes statistical independence between mixture fraction and its variance and results in poor predictions of time-averaged temperature and velocity. The second combustion model makes use of the PDF transport equation for mixture fraction and does not employ the statistical independence assumption. Results using this model show good agreement with experimental data for both the 2D and 3D LES, indicating that the use of statistical independence between mixture fraction and its dissipation is not valid for pool fire simulations. Lastly, "finger-like" flow structures near the base of the plume, generated from stream-wise vorticity, are shown to be important mixing mechanisms for accurate prediction of time-averaged temperature and velocity.
The concept of genetic divisors can be given a quantitative measure with a non-Archimedean p-adic metric that is both computationally convenient and physically motivated. For two particles possessing distinct mass parameters x and y, the metric distance D(x, y) is expressed on the field of rational numbers Q as the inverse of the greatest common divisor [gcd (x , y)]. As a measure of genetic similarity, this metric can be applied to (1) the mass numbers of particle states and (2) the corresponding subgroup orders of these systems. The use of the Bezout identity in the form of a congruence for the expression of the gcd (x , y) corresponding to the v{sub e} and {sub {mu}} neutrinos (a) connects the genetic divisor concept to the cosmic seesaw congruence, (b) provides support for the {delta}-conjecture concerning the subgroup structure of particle states, and (c) quantitatively strengthens the interlocking relationships joining the values of the prospectively derived (i) electron neutrino (v{sub e}) mass (0.808 meV), (ii) muon neutrino (v{sub {mu}}) mass (27.68 meV), and (iii) unified strong-electroweak coupling constant ({alpha}*{sup -1} = 34.26).
Alkylation reactions of benzene with propylene using zeolites were studied for their affinity for cumene production. The current process for the production of cumene involves heating corrosive acid catalysts, cooling, transporting, and distillation. This study focused on the reaction of products in a static one-pot vessel using non-corrosive zeolite catalysts, working towards a more efficient one-step process with a potentially large energy savings. A series of experiments were conducted to find the best reaction conditions yielding the highest production of cumene. The experiments looked at cumene formation amounts in two different reaction vessels that had different physical traits. Different zeolites, temperatures, mixing speeds, and amounts of reactants were also investigated to find their affects on the amount of cumene produced. Quantitative analysis of product mixture was performed by gas chromatography. Mass spectroscopy was also utilized to observe the gas phase components during the alkylation process.
The ultimate goal of many environmental measurements is to determine the risk posed to humans or ecosystems by various contaminants. Conventional environmental monitoring typically requires extensive sampling grids covering several media including air, water, soil and vegetation. A far more efficient, innovative and inexpensive tactic has been found using honeybees as sampling mechanisms. Members from a single bee colony forage over large areas ({approx}2 x 10{sup 6} m{sup 2}), making tens of thousands of trips per day, and return to a fixed location where sampling can be conveniently conducted. The bees are in direct contact with the air, water, soil and vegetation where they encounter and collect any contaminants that are present in gaseous, liquid and particulate form. The monitoring of honeybees when they return to the hive provides a rapid method to assess chemical distributions and impacts (1). The primary goal of this technology is to evaluate the efficiency of the transport mechanism (honeybees) to the hive using preconcentrators to collect samples. Once the extent and nature of the contaminant exposure has been characterized, resources can be distributed and environmental monitoring designs efficiently directed to the most appropriate locations. Methyl salicylate, a chemical agent surrogate was used as the target compound in this study.
Using intense magnetic pressure, a method was developed to launch flyer plates to velocities in excess of 20 km/s. This technique was used to perform plate-impact, shock wave experiments on cryogenic liquid deuterium (LD{sub 2}) to examine its high-pressure equation of state (EOS). Using an impedance matching method, Hugoniot measurements were obtained in the pressure range of 30-70 GPa. The results of these experiments disagree with previously reported Hugoniot measurements of LD{sub 2} in the pressure range above {approx}40 GPa, but are in good agreement with first principles, ab-initio models for hydrogen and its isotopes.
Sandstones that overlie or that are interbedded with evaporitic or other ductile strata commonly contain numerous localized domains of fractures, each covering an area of a few square miles. Fractures within the Entrada Sandstone at the Salt Valley Anticline are associated with salt mobility within the underlying Paradox Formation. The fracture relationships observed at Salt Valley (along with examples from Paleozoic strata at the southern edge of the Holbrook basin in northeastern Arizona, and sandstones of the Frontier Formation along the western edge of the Green River basin in southwestern Wyoming), show that although each fracture domain may contain consistently oriented fractures, the orientations and patterns of the fractures vary considerably from domain to domain. Most of the fracture patterns in the brittle sandstones are related to local stresses created by subtle, irregular flexures resulting from mobility of the associated, interbedded ductile strata (halite or shale). Sequential episodes of evaporite dissolution and/or mobility in different directions can result in multiple, superimposed fracture sets in the associated sandstones. Multiple sets of superimposed fractures create reservoir-quality fracture interconnectivity within restricted localities of a formation. However, it is difficult to predict the orientations and characteristics of this type of fracturing in the subsurface. This is primarily because the orientations and characteristics of these fractures typically have little relationship to the regional tectonic stresses that might be used to predict fracture characteristics prior to drilling. Nevertheless, the high probability of numerous, intersecting fractures in such settings attests to the importance of determining fracture orientations in these types of fractured reservoirs.
Carbon is an important support for heterogeneous catalysts, such as platinum supported on activated carbon (AC). An important property of these catalysts is that they decompose upon heating in air. Consequently, Pt/AC catalysts can be used in applications requiring rapid decomposition of a material, leaving little residue. This report describes the catalytic effects of platinum on carbon decomposition in an attempt to maximize decomposition rates. Catalysts were prepared by impregnating the AC with two different Pt precursors, Pt(NH{sub 3}){sub 4}(NO{sub 3}){sub 2} and H{sub 2}PtCl{sub 6}. Some catalysts were treated in flowing N{sub 2} or H{sub 2} at elevated temperatures to decompose the Pt precursor. The catalysts were analyzed for weight loss in air at temperatures ranging from 375 to 450 C, using thermogravimetric analysis (TGA). The following results were obtained: (1) Pt/AC decomposes much faster than pure carbon; (2) treatment of the as-prepared 1% Pt/AC samples in N{sub 2} or H{sub 2} enhances decomposition; (3) autocatalytic behavior is observed for 1% Pt/AC samples at temperatures {ge} 425 C; (4) oxygen is needed for decomposition to occur. Overall, the Pt/AC catalyst with the highest activity was impregnated with H{sub 2}PtCl{sub 6} dissolved in acetone, and then treated in H{sub 2}. However, further research and development should produce a more active Pt/AC material.
The Microsystems Subgrid Physics project is intended to address gaps between developing high-performance modeling and simulation capabilities and microdomain specific physics. The initial effort has focused on incorporating electrostatic excitations, adhesive surface interactions, and scale dependent material and thermal properties into existing modeling capabilities. Developments related to each of these efforts are summarized, and sample applications are presented. While detailed models of the relevant physics are still being developed, a general modeling framework is emerging that can be extended to incorporate evolving material and surface interaction modules.
Recently an innovative technique known as the Isentropic Compression Experiment (ICE) was developed that allows the dynamic compressibility curve of a material to be measured in a single experiment. Hence, ICE significantly reduces the cost and time required for generating and validating theoretical models of dynamic material response. ICE has been successfully demonstrated on several materials using the 20 MA Z accelerator, resulting in a large demand for its use. The present project has demonstrated its use on another accelerator, Saturn. In the course of this study, Saturn was tailored to produce a satisfactory drive time structure, and instrumented to produce velocity data. Pressure limits are observed to be approximately 10-15 GPa (''LP'' configuration) or 40-50 GPa (''HP'' configuration), depending on sample material. Drive reproducibility (panel to panel within a shot and between shots) is adequate for useful experimentation, but alignment fixturing problems make it difficult to achieve the same precision as is possible at Z. Other highlights included the useful comparison of slightly different PZT and ALOX compositions (neutron generator materials), temperature measurement using optical pyrometry, and the development of a new technique for preheating samples. 28 ICE tests have been conducted at Saturn to date, including the experiments described herein.
Sandia is investigating the shock response of single-crystal diamond up to several Mbar pressure in a collaborative effort with the Institute for Shock Physics (ISP) at Washington State University (WSU). This is project intended to determine (i) the usefulness of diamond as a window material for high pressure velocity interferometry measurements, (ii) the maximum stress level at which diamond remains transparent in the visible region, (iii) if a two-wave structure can be detected and analyzed, and if so, (iv) the Hugoniot elastic limit (HEL) for the [110] orientation of diamond. To this end experiments have been designed and performed, scoping the shock response in diamond in the 2-3 Mbar pressure range using conventional velocity interferometry techniques (conventional VISAR diagnostic). In order to perform more detailed and highly resolved measurements, an improved line-imaging VISAR has been developed and experiments using this technique have been designed. Prior to performing these more detailed experiments, additional scoping experiments are being performed using conventional techniques at WSU to refine the experimental design.
Explosive charges placed on the fuze end of a drained chemical munition are expected to be used as a means to destroy the fuze and burster charges of the munition. Analyses are presented to evaluate the effect of these additional initiation charges on the fragmentation characteristics for the M121A1 155mm chemical munition, modeled with a T244 fuze attached, and to assess the consequences of these fragment impacts on the walls of a containment chamber--the Burster Detonation Vessel. A numerical shock physics code (CTH) is used to characterize the mass and velocity of munition fragments. Both two- and three-dimensional simulations of the munition have been completed in this study. Based on threshold fragment velocity/mass results drawn from both previous and current analyses, it is determined that under all fragment impact conditions from the munition configurations considered in this study, no perforation of the inner chamber wall will occur, and the integrity of the Burster Detonation Vessel is retained. However, the munition case fragments have sufficient mass and velocity to locally damage the surface of the inner wall of the containment vessel.
Schells, Regina L.; Bogdan, Carolyn W.; Wix, Steven D.
This document describes the High Performance Electrical Modeling and Simulation (HPEMS) Global Verification Test Suite (VERTS). The VERTS is a regression test suite used for verification of the electrical circuit simulation codes currently being developed by the HPEMS code development team. This document contains descriptions of the Tier I test cases.
The Geometric Search Engine is a software system for storing and searching a database of geometric models. The database maybe searched for modeled objects similar in shape to a target model supplied by the user. The database models are generally from CAD models while the target model may be either a CAD model or a model generated from range data collected from a physical object. This document describes key generation, database layout, and search of the database.
This report provides a summary of the work completed in the Source Code Assurance Tool project. This work was done as part of the Laboratory Directed Research and Development program.
This report provides a preliminary functional description of a novel software application, the Source Code Assurance Tool, which would assist a system analyst in the software assessment process. An overview is given of the tool's functionality and design; and how the analyst would use it to assess a body of source code. This work was done as part of a Laboratory Directed Research and Development project.
In this paper we describe a new language, Visual Structure Language (VSL), designed to describe the structure of a program and explain its pieces. This new language is built on top of a general-purpose language, such as C. The language consists of three extensions: explanations, nesting, and arcs. Explanations are comments explicitly associated with code segments. These explanations can be nested. And arcs can be inserted between explanations to show data- or control-flow. The value of VSL is that it enables a developer to better control a code. The developer can represent the structure via nested explanations, using arcs to indicate the flow of data and control. The explanations provide a ''second opinion'' about the code so that at any level, the developer can confirm that the code operates as it is intended to do. We believe that VSL enables a programmer to use in a computer language the same model--a hierarchy of components--that they use in their heads when they conceptualize systems.
We present the tool we built as part of a Laboratory Directed Research and Development (LDRD) project. This tool consists of a commercially-available, graphical editor front-end, combined with a back end ''slicer.'' The significance of the tool is that it shows how to slice across system components. This is an advance from slicing across program components.
This report details experimental data useful in validating radiative transfer codes involving participating media, particularly for cases involving combustion. Special emphasis is on data for pool fires. Features sought in the references are: Flame geometry and fuel that approximate conditions for a pool fire or a well-defined flame geometry and characteristics that can be completely modeled; detailed information that could be used as code input data, including species concentration and temperature profiles and associated absorption coefficients, soot morphology and concentration profiles, associated scattering coefficients and phase functions, specification of system geometry, and system boundary conditions; detailed information that could be compared against code output predictions, including measured boundary radiative energy flux distributions (preferably spectral) and/or boundary temperature distributions; and a careful experimental error analysis so that code predictions could be rationally compared with experimental measurements. Reference data were gathered from more than 35 persons known to be active in the field of radiative transfer and combustion, particularly in experimental work. A literature search was carried out using key words. Additionally, the reference lists in papers/reports were pursued for additional leads. The report presents extended abstracts of the cited references, with comments on available and missing data for code validation, and comments on reported error. A graphic for quick reference is added to each abstract that indicates the completeness of data and how well the data mimics a large-scale pool fire. The references are organized into Lab-Scale Pool Fires, Large-Scale Pool Fires, Momentum-Driven Diffusion Flames, and Enclosure Fires. As an additional aid to report users, the Tables in Appendix A show the types of data included in each reference. The organization of the tables follows that used for the abstracts.
Sandia National Laboratories is developing innovative alternative technology to replace open burn/open detonation (OB/OD) operations for the destruction and disposal of obsolete, excess, and off-spec energetic materials. Alternatives to OB/OD are necessary to comply with increasingly stringent regulations. This program is developing an alternative technology to destruct energetic materials using organic amines with minimal discharge of toxic chemicals to the environment and defining the application of the by-products for the manufacture of structural materials.
Wire explosion experiments have been carried out at the University of Nevada, Reno. These experiments investigated the explosion phase of wires with properties and current-driving conditions comparable to that used in the initial stage of wire array z-pinch implosions on the Z machine at Sandia National Laboratories. Specifically, current pulses similar to and faster than the pre-pulse current on Z (current prior to fast rise in current pulse) were applied to single wire loads to study wire heating and the early development of plasmas in the wire initiation process. Understanding such issues are important to larger pulsed power machines that implode cylindrical wire array loads comprised of many wires. It is thought that the topology of an array prior to its acceleration influences the implosion and final stagnation properties, and therefore may depend on the initiation phase of the wires. Single wires ranging from 4 to 40 pm in diameter and comprised of material ranging from AI to W were investigated. Several diagnostics were employed to determine wire current, voltage, total emitted-light energy and power, along with the wire expansion velocity throughout the explosion. In a number of cases, the explosion process was also observed with x-ray backlighting using x-pinches. The experimental data indicates that the characteristics of a wire explosion depend dramatically on the rate of rise of the current, on the diameter of the wire, and on the heat of vaporization of the wire material. In this report, these characteristics will be described in detail. Of particular interest is the result that a faster current rise produces a higher energy deposition into the wire prior to explosion. This result introduces a different means of increasing the efficiency of wire heating. In this case, the energy deposition along the wire and its subsequent expansion, is uniform compared to a ''slow'' current rise (170 A/ns compared to 22 A /s current rise into a short circuit) and the expansion velocity is larger. The energy deposition and wire expansion is further modified by the wire diameter and material. Investigations of wire diameter indicate that the diameter primarily effects the expansion velocity and energy deposition; thicker wires explode with greater velocities but absorb less energy per atom. The heat of vaporization also categorizes the wire explosion; wires with a low heat of vaporization expand faster and emit less radiation than their high heat of vaporization counterparts.
An important capability in conducting underground nuclear tests is to be able to determine the nuclear test yield accurately within hours after a test. Due to a nuclear test moratorium, the seismic method that has been used in the past has not been exercised since a non-proliferation high explosive test in 1993. Since that time, the seismic recording system and the computing environment have been replaced with modern equipment. This report describes the actions that have been taken to preserve the capability for determining seismic yield, in the event that nuclear testing should resume. Specifically, this report describes actions taken to preserve seismic data, actions taken to modernize software, and actions taken to document procedures. It concludes with a summary of the current state of the data system and makes recommendations for maintaining this system in the future.
This report describes testing of prototype InfiniBand{trademark} host channel adapters from Intel Corporation, using the Linux(reg sign) operating system. Three generations of prototype hardware were obtained, and Linux device drivers were written which exercised the data movement capabilities of the cards. Latency and throughput results obtained were similar to other SAN technologies, but not significantly better.
This project set out to scientifically-tailor ''smart'' interfacial films and 3-D composite nanostructures to exhibit photochromic responses to specific, highly-localized chemical and/or mechanical stimuli, and to integrate them into optical microsystems. The project involved the design of functionalized chromophoric self-assembled materials that possessed intense and environmentally-sensitive optical properties (absorbance, fluorescence) enabling their use as detectors of specific stimuli and transducers when interfaced with optical probes. The conjugated polymer polydiacetylene (PDA) proved to be the most promising material in many respects, although it had some drawbacks concerning reversibility. Throughout his work we used multi-task scanning probes (AFM, NSOM), offering simultaneous optical and interfacial force capabilities, to actuate and characterize the PDA with localized and specific interactions for detailed characterization of physical mechanisms and parameters. In addition to forming high quality mono-, bi-, and tri-layers of PDA via Langmuir-Blodgett deposition, we were successful in using the diacetylene monomer precursor as a surfactant that directed the self-assembly of an ordered, mesostructured inorganic host matrix. Remarkably, the diacetylene was polymerized in the matrix, thus providing a PDA-silica composite. The inorganic matrix serves as a perm-selective barrier to chemical and biological agents and provides structural support for improved material durability in microsystems. Our original goal was to use the composite films as a direct interface with microscale devices as optical elements (e.g., intracavity mirrors, diffraction gratings), taking advantage of the very high sensitivity of device performance to real-time dielectric changes in the films. However, our optical physics colleagues (M. Crawford and S. Kemme) were unsuccessful in these efforts, mainly due to the poor optical quality of the composite films.
The intention of this project was to collaborate with Harvard University in the general area of nanoscale structures, biomolecular materials and their application in support of Sandia's MEMS technology. The expertise at Harvard was crucial in fostering these fundamentally interdisciplinary developments. Areas that were of interest included: (1) nanofabrication that exploits traditional methods (from Si technology) and developing new methods; (2) self-assembly of organic and inorganic systems; (3) assembly and dynamics of membranes and microfluidics; (4) study of the hierarchy of scales in assembly; (5) innovative imaging methods; and (6) hard (engineering)/soft (biological) interfaces. Specifically, we decided to work with Harvard to design and construct an experimental test station to measure molecular transport through single nanopores. The pore may be of natural origin, such as a self-assembled bacterial protein in a lipid bilayer, or an artificial structure in silicon or silicon nitride.
This report documents work supporting the Sandia National Laboratories initiative in Distributed Energy Resources (DERs) and Supervisory Control and Data Acquisition (SCADA) systems. One approach for real-time control of power generation assets using feedback control, Quantitative feedback theory (QFT), has recently been applied to voltage, frequency, and phase-control of power systems at Sandia. QFT provided a simple yet powerful philosophy for designing the control systems--allowing the designer to optimize the system by making design tradeoffs without getting lost in complex mathematics. The feedback systems were effective in reducing sensitivity to large and sudden changes in the power grid system. Voltage, frequency, and phase were accurately controlled, even with large disturbances to the power grid system.
This report is divided into two parts: a study of the glass transition in confined geometries, and formation mechanisms of block copolymer mesophases by solvent evaporation-induced self-assembly. The effect of geometrical confinement on the glass transition of polymers is a very important consideration for applications of polymers in nanotechnology applications. We hypothesize that the shift of the glass transition temperature of polymers in confined geometries can be attributed to the inhomogeneous density profile of the liquid. Accordingly, we assume that the glass temperature in the inhomogeneous state can be approximated by the Tg of a corresponding homogeneous, bulk polymer, but at a density equal to the average density of the inhomogeneous system. Simple models based on this hypothesis give results that are in remarkable agreement with experimental measurements of the glass transition of confined liquids. Evaporation-induced self-assembly (EISA) of block copolymers is a versatile process for producing novel, nanostructured materials and is the focus of much of the experimental work at Sandia in the Brinker group. In the EISA process, as the solvent preferentially evaporates from a cast film, two possible scenarios can occur: microphase separation or micellization of the block copolymers in solution. In the present investigation, we established the conditions that dictate which scenario takes place. Our approach makes use of scaling arguments to determine whether the overlap concentration c* occurs before or after the critical micelle concentration (CMC). These theoretical arguments are used to interpret recent experimental results of Yu and collaborators on EISA experiments on Silica/PS-PEO systems.
In exploring the question of how humans reason in ambiguous situations or in the absence of complete information, we stumbled onto a body of knowledge that addresses issues beyond the original scope of our effort. We have begun to understand the importance that philosophy, in particular the work of C. S. Peirce, plays in developing models of human cognition and of information theory in general. We have a foundation that can serve as a basis for further studies in cognition and decision making. Peircean philosophy provides a foundation for understanding human reasoning and capturing behavioral characteristics of decision makers due to cultural, physiological, and psychological effects. The present paper describes this philosophical approach to understanding the underpinnings of human reasoning. We present the work of C. S. Peirce, and define sets of fundamental reasoning behavior that would be captured in the mathematical constructs of these newer technologies and would be able to interact in an agent type framework. Further, we propose the adoption of a hybrid reasoning model based on his work for future computational representations or emulations of human cognition.
This article summarizes information related to the automated course of action (COA) development effort. The information contained in this document puts the COA effort into an operational perspective that addresses command and control theory, as well as touching on the military planning concept known as effects-based operations. The sections relating to the COA effort detail the rationale behind the functional models developed and identify technologies that could support the process functions. The functional models include a section related to adversarial modeling, which adds a dynamic to the COA process that is missing in current combat simulations. The information contained in this article lays the foundation for building a unique analytic capability.
This report is an update to previous ''smart gun'' work and the corresponding report that were completed in 1996. It incorporates some new terminology and expanded definitions. This effort is the product of an open source look at what has happened to the ''smart gun'' technology landscape since the 1996 report was published.
The Comprehensive Test Ban Treaty of 1996 banned any future nuclear explosions or testing of nuclear weapons and created the CTBTO in Vienna to implement the treaty. The U.S. response to this was the cessation of all above and below ground nuclear testing. As such, all stockpile reliability assessments are now based on periodic testing of subsystems being stored in a wide variety of environments. This data provides a wealth of information and feeds a growing web of deterministic, physics-based computer models for assessment of stockpile reliability. Unfortunately until 1996 it was difficult to relate the deterministic materials aging test data to component reliability. Since that time we have made great strides in mathematical techniques and computer tools that permit explicit relationships between materials degradation, e.g. corrosion, thermo-mechanical fatigue, and reliability. The resulting suite of tools is known as CRAX and the mathematical library supporting these tools is Cassandra. However, these techniques ignore the historical data that is also available on similar systems in the nuclear stockpile, the DoD weapons complex and even in commercial applications. Traditional statistical techniques commonly used in classical re liability assessment do not permit data from these sources to be easily included in the overall assessment of system reliability. An older, alternative approach based on Bayesian probability theory permits the inclusion of data from all applicable sources. Data from a variety of sources is brought together in a logical fashion through the repeated application of inductive mathematics. This research brings together existing mathematical methods, modifies and expands those techniques as required, permitting data from a wide variety of sources to be combined in a logical fashion to increase the confidence in the reliability assessment of the nuclear weapons stockpile. The application of this research is limited to those systems composed of discrete components, e.g. those that can be characterized as operating or not operating. However, there is nothing unique about the underlying principles and the extension to continuous subsystem/systems is straightforward. The framework is also laid for the consideration of systems with multiple correlated failure modes. While an important consideration, time and resources limited the specific demonstration of these methods.