Publications

In certain penetration events the primary mode of deformation of the target can be approximated by known analytical expressions. In the context of an analysis code, this approximation eliminates the need for modeling the target as well as the need for a contact algorithm. This technique substantially reduces execution time. In this spirit, a forcing function which is derived from a spherical-cavity expansion analysis has been implemented in PRONTO 3D. This implementation is capable of computing the structural and component responses of a projectile due to three dimensional penetration events. Sample problems demonstrate good agreement with experimental and analytical results.

This report documents the work performed for the ``Advanced Tomographic Flow Diagnostics for Opaque Multiphase Fluids`` LDRD (Laboratory-Directed Research and Development) project and is presented as the fulfillment of the LDRD reporting requirement. Dispersed multiphase flows, particularly gas-liquid flows, are industrially important to the chemical and applied-energy industries, where bubble-column reactors are employed for chemical synthesis and waste treatment. Due to the large range of length scales (10{sup {minus}6}-10{sup 1}m) inherent in real systems, direct numerical simulation is not possible at present, so computational simulations are forced to use models of subgrid-scale processes, the accuracy of which strongly impacts simulation fidelity. The development and validation of such subgrid-scale models requires data sets at representative conditions. The ideal measurement techniques would provide spatially and temporally resolved full-field measurements of the distributions of all phases, their velocity fields, and additional associated quantities such as pressure and temperature. No technique or set of techniques is known that satisfies this requirement. In this study, efforts are focused on characterizing the spatial distribution of the phases in two-phase gas-liquid flow and in three-phase gas-liquid-solid flow. Due to its industrial importance, the bubble-column geometry is selected for diagnostics development and assessment. Two bubble-column testbeds are utilized: one at laboratory scale and one close to industrial scale. Several techniques for measuring the phase distributions at conditions of industrial interest are examined: level-rise measurements, differential-pressure measurements, bulk electrical impedance measurements, electrical bubble probes, x-ray tomography, gamma-densitometry tomography, and electrical impedance tomography.

MC1814 Interconnection Boxes from dismantled B57 bombs, and MC2839 firing Sets from retired W70-1 warheads were obtained from the Pantex facility. Printed circuit boards were selected from these components for microstructural analysis of their solder joints. The analysis included a qualitative examination of the solder joints and quantitative assessments of (1) the thickness of the intermetallic compound layer that formed between the solder and circuit board Cu features, and (2) the Pb-rich phase particle distribution within the solder joint microstructure. The MC2839 solder joints had very good workmanship qualities. The intermetallic compound layer stoichiometry was determined to be that of Cu6Sn5. The mean intermetallic compound layer thickness for all solder joints was 0.885 mm. The magnitude of these values did not indicate significant growth over the weapon lifetime. The size distribution of the Pb-rich phase particles for each of the joints were represented by the mean of 9.85 {times} 10{sup {minus}6} mm{sup 2}. Assuming a spherical geometry, the mean particle diameter would be 3.54 mm. The joint-to-joint difference of intermetallic compound layer thickness and Pb-rich particle size distribution was not caused by varying thermal environments, but rather, was a result of natural variations in the joint microstructure that probably existed at the time of manufacture. The microstructural evaluation of the through-hole solder joints form the MC2839 and MC1814 components indicated that the environmental conditions to which these electronic units were exposed in the stockpile, were benign regarding solder joint aging. There was an absence of thermal fatigue damage in MC2839 circuit board, through-hole solder joints. The damage to the eyelet solder joints of the MC1814 more likely represented infant mortality failures at or very near the time of manufacture, resulting from a marginal design status of this type of solder joint design.

Phenomena that can decontaminate aerosol-laden gases sparging through steam suppression pools of boiling water reactors during reactor accidents are described. Uncertainties in aerosol properties, aerosol behavior within gas bubbles, and bubble behavior in plumes affect predictions of decontamination by steam suppression pools. Uncertainties in the boundary and initial conditions that are dictated by the progression of severe reactor accidents and that will affect predictions of decontamination by steam suppression pools are discussed. Ten parameters that characterize boundary and initial condition uncertainties, nine parameters that characterize aerosol property and behavior uncertainties, and eleven parameters that characterize uncertainties in the behavior of bubbles in steam suppression pools are identified. Ranges for the values of these parameters and subjective probability distributions for parametric values within the ranges are defined. These uncertain parameters are used in Monte Carlo uncertainty analyses to develop uncertainty distributions for the decontamination that can be achieved by steam suppression pools and the size distribution of aerosols that do emerge from such pools. A simplified model of decontamination by steam suppression pools is developed by correlating features of the uncertainty distributions for total decontamination factor, DF(total), mean size of emerging aerosol particles, d{sub p}, and the standard deviation of the emerging aerosol size distribution, {sigma}, with pool depth, H. Correlations of the median values of the uncertainty distributions are suggested as the best estimate of decontamination by suppression pools. Correlations of the 10 percentile and 90 percentile values of the uncertainty distributions characterize the uncertainty in the best estimates. 295 refs., 121 figs., 113 tabs.

Neutron reflection is one of only a few characterization techniques which can be used to study buried interfaces in situ. While restricted to model samples, interfacial density and composition profiles can be obtained with a resolution of {approx}5 {angstrom} using isotopic substitution (typically H/D for organic materials). We are using neutron reflection to address several problems of fundamental importance to the durability of organic/inorganic interphases. One important focus of this study is water adsorption within interphases with and without coupling agents. From the time and temperature dependence of moisture uptake and removal in vacuum, information regarding the nature of the interaction of water with the interphase species can be obtained.

This work was conducted as part of a Near-wellbore Mechanics program at Sandia National Laboratories. An understanding of the interaction of the perforator jet from an explosive shaped charge with the fluid filled porous sandstone media is of basic importance to the completion of oil wells. Tests were conducted using the five-head Flash X-ray Test Site to measure the jet tip velocities and jet geometry for the OMNI and CAPSULE Conical Shaped Charge (CSC) oil well perforator jets fired into air. These tests were conducted to generate jet velocity and geometry information to be used in validating the CTH hydrocode modeling/simulation development of pressed powder, metal liner jets in air. Ten tests were conducted to determine the CSC jet penetration into 6061-T6 aluminum targets. Five tests were conducted with the OMNI CSC at 0.25, 6.0, and 19 inch standoffs from the target. Five tests were conducted with the CAPSULE CSC at 0.60, 5.0, 10.0, and 19 inch standoffs from the target. These tests were conducted to generate jet penetration into homogeneous target information for use in validating the CTH code modeling/simulation of pressed powder, metal liner jets penetrating aluminum targets. The Flash X-ray radiographs, jet velocities, jet diameters, and jet lengths data for jets fired into air are presented in this report. The jet penetration into aluminum and penetration hole profile data are also presented for the OMNI and CAPSULE perforators. Least Squares fits are presented for the measured jet velocity and jet penetration data.

Large scale experiments were performed to determine the effectiveness of thermal glow plug igniters to burn hydrogen in a condensing steam environment due to the presence of water sprays. The experiments were designed to determine if a detonation or accelerated flame could occur in a hydrogen-air-steam mixture which was initially nonflammable due to steam dilution but was rendered flammable by rapid steam condensation due to water sprays. Eleven Hydrogen Igniter Tests were conducted in the test vessel. The vessel was instrumented with pressure transducers, thermocouple rakes, gas grab sample bottles, hydrogen microsensors, and cameras. The vessel contained two prototypic engineered systems: (1) a deliberate hydrogen ignition system and (2) a water spray system. Experiments were conducted under conditions scaled to be nearly prototypic of those expected in Advanced Light Water Reactors (such as the Combustion Engineering (CE) System 80+), with prototypic spray drop diameter, spray mass flux, steam condensation rates, hydrogen injection flow rates, and using the actual proposed plant igniters. The lack of any significant pressure increase during the majority of the burn and condensation events signified that localized, benign hydrogen deflagration(s) occurred with no significant pressure load on the containment vessel. Igniter location did not appear to be a factor in the open geometry. Initially stratified tests with a stoichiometric mixture in the top showed that the water spray effectively mixes the initially stratified atmosphere prior to the deflagration event. All tests demonstrated that thermal glow plugs ignite hydrogen-air-steam mixtures under conditions with water sprays near the flammability limits previously determined for hydrogen-air-steam mixtures under quiescent conditions. This report describes these experiments, gives experimental results, and provides interpretation of the results. 12 refs., 127 figs., 16 tabs.

Metathesis-catalyzed polymerizations of primary silanes were performed to generate polysilanes suitable for functionalization with a variety of side groups. Modeling was employed to predict conformations and estimate electronic properties of candidate functionalized polysilanes. Chemical functionalization of oligo(hydrido)silanes with terminal {alpha}, {omega}-dienes under free radical conditions yielded highly crosslinked, nonporous polysilane networks. Ketone reduction with oligo(hydrido)silanes under free radical conditions led to novel poly(phenylalkoxysilanes). Free radical reduction of terminal alkenyl(alkoxy)silanes forms functionalized polysilanes which can be further transformed into sol-gel matrices with the polysilane functionality intact. These gels may be processed into nonporous xerogels or high surface area aerogels.

Ion-beam driven hohlraum targets were designed to absorb the energy of PBFAII lithium ion beams within a foam, which converted the ion beam energy into x-rays. The foam was held within a gold hohlraum. X-ray radiation was observed from the top of the target through a circular diagnostic aperture. On the bottom of the target was a gold-coated aluminum witness plate, which was a component of an active, shock-breakout diagnostic. Surrounding the outside of the hohlraum were five titanium pins which produced ion-induced inner-shell x-rays (4.5 keV) to diagnose the lithium beam. Several different manufacturing processes and characterization techniques were utilized to prepare these targets. Extensive documentation provided quality control on their preparation. This report summarizes the preparation, characterization, and documentation of targets for ion-beam driven hohlraum experiments.

A team of analysts designed and conducted a scoping evaluation to estimate the technical capabilities of fifteen Department of Energy sites for disposal of the hazardous metals in mixed low-level waste (i.e., waste that contains both low-level radioactive materials and hazardous constituents). Eight hazardous metals were evaluated: arsenic, barium, cadmium, chromium, lead, mercury, selenium, and silver. The analysis considered transport only through the groundwater pathway. The results are reported as site-specific estimates of maximum concentrations of each hazardous metal in treated mixed low-level waste that do not exceed the performance measures established for the analysis. Also reported are site-specific estimates of travel times of each hazardous metal to the point of compliance.

Central Europe has experienced environmental degradation for hundreds of years. The proximity of countries, their shared resources, and transboundary movement of environmental pollution, create the potential for regional environmental strife. The goal of this project was to identify the sources and sinks of environmental pollution in Central Europe and evaluate the possible impact of transboundary movement of pollution on the countries of Central Europe. In meeting the objectives of identifying sources of contaminants, determining transboundary movement of contaminants, and assessing socio-economic implications, large quantities of disparate data were examined. To facilitate use of the data, the authors refined mapping procedures that enable processing information from virtually any map or spreadsheet data that can be geo-referenced. Because the procedure is freed from a priori constraints of scale that confound most Geographical Information Systems, they have the capacity to generate new projections and apply sophisticated statistical analyses to the data. The analysis indicates substantial environmental problems. While transboundary pollution issues may spawn conflict among the Central European countries and their neighbors, it appears that common environmental problems facing the entire region have had the effect of bringing the countries together, even though opportunities for deteriorating relationships may still arise.

The goal of this work was to evaluate chemically-functionalized block copolymers as adhesion promoters for metal/thermoset resin interfaces. Novel block copolymers were synthesized which contain pendant functional groups reactive toward copper and epoxy resins. In particular, imidazole and triazole functionalities that chelate with copper were incorporated onto one block, while secondary amines were incorporated onto the second block. These copolymers were found to self-assemble from solution onto copper surfaces to form monolayers. The structure of the adsorbed monolayers were studied in detail by neutron reflection and time-of-flight secondary ion mass spectrometry. The monolayer structure was found to vary markedly with the solution conditions and adsorption protocol. Appropriate conditions were found for which the two blocks form separate layers on the surface with the amine functionalized block exposed at the air surface. Adhesion testing of block copolymer-coated copper with epoxy resins was performed in both lap shear and peel modes. Modest enhancements in bond strengths were observed with the block copolymer applied to the native oxide. However, it was discovered that the native oxide is the weak link, and that by simply removing the native oxide, and then applying an epoxy resin before the native oxide can reform, excellent bond strength in the as-prepared state as well as excellent retention of bond strength after exposure to solder in ambient conditions are obtained. It is recommended that long term aging studies be performed with and without the block copolymer. In addition, the functionalized block copolymer method should be evaluated for another system that has inherently poor bonding, such as the nickel/silicone interface, and for systems involving metals and alloys which form oxides very rapidly, such as aluminum and stainless steel, where bonding strategies involve stabilizing the native oxide.

In-pile experiments addressing late-phase processes in Light Water Reactors (LWRs) were performed in the Annular Core Research Reactor (ACRR) at Sandia National Laboratories. Melt Progression (MP) experiments were designed to provide information to develop and verify computer models for analysis of LWR core damage in severe accidents. Experiments examine the formation and motion of ceramic molten pools in disrupted reactor core regions. The MP-2 experiment assembly consisted of: (1) a rubble bed of enriched UO{sub 2} and ZrO{sub 2} simulating severely disrupted reactor core regions, (2) a ceramic/metallic crust representing blockage formed by early phase melting, relocation, and refreezing of core components, and (3) an intact rod stub region that remained in place below the blockage region. The test assembly was fission heated in the central cavity of the ACRR at an average rate of about 0.2 KA, reaching a peak molten pool temperature around 3400 K. Melting of the debris bed ceramic components was initiated near the center of the bed. The molten material relocated downward, refreezing to form a ceramic crust near the bottom of the rubble bed. As power levels were increased, the crust gradually remelted and reformed at progressively lower positions in the bed until late in the experiment when it penetrated into and attacked the ceramic/metallic blockage. The metallic components of the blockage region melted and relocated to the bottom of the intact rod stub region before the ceramic melt penetrated the blockage region from above. The ceramic pool penetrated halfway into the blockage region by the end of the experiment. Measurements of thermal response and material relocation are compared to the results of the computer simulations. Postexperiment examination of the assembly with the associated material interactions and metallurgy are also discussed in detail with the analyses and interpretation of results. 16 refs., 206 figs., 24 tabs.

The capabilities of Interfacial Force Microscopy (IFM) are illustrated utilizing the following examples: the bonding interaction between chemically distinct end groups on self-assembling molecules adsorbed on the sample and and probe tip; and a study of the effect of morphological defects on the nanomechanical properties of gold single crystal surfaces.

Different applications have different security requirements for data privacy, data integrity, and authentication. Encryption is one technique that addresses these requirements. Encryption hardware, designed for use in high-speed communications networks, can satisfy a wide variety of security requirements if that hardware is key-agile, robustness-agile and algorithm-agile. Hence, multiply-agile encryption provides enhanced solutions to the secrecy, interoperability and quality of service issues in high-speed networks. This paper defines these three types of agile encryption. Next, implementation issues are discussed. While single-algorithm, key-agile encryptors exist, robustness-agile and algorithm-agile encryptors are still research topics.

The Korean Peninsula is one of the world`s most tense military confrontational sites. Nearly 2 million North Korean, South Korean, and U.S. troops face each other along the 255-km long military demarcation line. Confidence building measures (CBMs), particularly military ones, that address the security needs of both countries could decrease the danger of conflict and help create an environment where a peace regime might be negotiated. In spite of the present high level of mutual distrust, steps can still be taken to prepare for future development and implementation of CBMs. This paper defines some simple and specific first steps toward CBMs that might be useful on the Korean Peninsula.

Under the sponsorship of the US Department of Energy (DOE) Office of Utility Technologies, the Energy Storage Systems Analysis and Development Department at Sandia National Laboratories contracted Sentech, Inc., to assess the impact of power quality problems on the electricity supply system. This report contains the results of several studies that have identified the cost of power quality events for electricity users and providers. The large annual cost of poor power quality represents a national inefficiency and is reflected in the cost of goods sold, reducing US competitiveness. The Energy Storage Systems (ESS) Program takes the position that mitigation merits the attention of not only the DOE but affected industries as well as businesses capable of assisting in developing solutions to these problems. This study represents the preliminary stages of an overall strategy by the ESS Program to understand the magnitude of these problems so as to begin the process of engaging industry partners in developing solutions.

End-to-end encryption can protect proprietary information as it passes through a complex inter-city computer network, even if the intermediate systems are untrusted. This technique involves encrypting the body of computer messages while leaving network addressing and control information unencrypted for processing by intermediate network nodes. Because high speed implementations of end-to-end encryption with easy key management for standard network protocols are unavailable, this technique is not widely used today. Specifically, no end-to-end encryptors exist to protect Asynchronous Transfer Mode (ATM) traffic, nor to protect Switched Multi-megabit Data Service (SMDS), which is the first ``Broadband Integrated Services Digital Network`` (BISDN) service now being used by long distance telephone companies. This encryption technology is required for the protection of data in transit between industrial sites and central Massively Parallel Supercomputing Centers over high bandwidth, variable bit rate (BISDN) services. This research effort investigated techniques to scale end-to-end encryption technology from today`s state of the art ({approximately} 0.001 Gb/s) to 2.4 Gb/s and higher. A cryptosystem design has been developed which scales for implementation beyond SONET OC-48 (2.4Gb/s) data rates. A prototype for use with OC-3 (0.155 Gb/s) ATM variable bit rate services was developed.

Nanometer sized metal particles were encapsulated in the micropores of xerogels and aerogels. The synthesis involves the sequential reduction of a metal salt followed by sol-gel processing in an inverse micelle solution. The inverse micelle solution solubilizes the metal salt and provides a micro-reactor for the nucleation, growth, and stabilization of the nanometer sized clusters. Hydrolysis and condensation of an added siloxane precursor produces a wet gel embedding the particles. Characterization of the particle size and composition and the particle growth process was completed with transmission electron microscopy (TEM), electron diffraction, and UV-visible absorption spectrometry. Characterization of the gel surface areas was completed with N{sub 2} porosimetry. Material properties determined as a function of the gel precursor (TEOS vs. a pre-hydrolyzed form of TEOS), the water to gel precursor reaction stoichiometry, and surfactant concentration are discussed in terms of the unique solution chemistry occurring in the micro-heterogeneous inverse micelle solutions. Finally, catalyst development and catalyst activity of the materials are discussed. 1-hexene hydrogenation was chosen as a model reaction.

Dispensable materials, such as sticky foams and rigid polyurethane foams, have been used as access deterrent systems by DOE security since the 1970`s. While these have been very effective systems, they also have some intrinsic problems such as toxicity, flammability and a limited range of temperature in which they remain functional. Current trends to use less-than-lethal methods to gain advantage in military and civilian conflict scenarios demand that new and better deterrent materials be designed. The most effective sticky foam is a hydrocarbon-based material which is composed of high molecular weight polymers, low molecular weight tackifying agents, fire retardants and foam stabilizing surfactants. In order to expand and fully utilize sticky foam technology, a truly nonflammable analog is required. To this end, this work involves first generation development of silicone-based deterrent systems. Two basic types of silicone systems were evaluated. First, systems based on commercial resins were prepared using a variety of thixotropic materials, plasticizers and formulation strategies. Second, systems were prepared using in situ sol-gel techniques to rapidly promote gelation in blends of functionalized silicone polymers. The resulting materials were evaluated for their foamability using non-CFC foaming agents and found to be suitable for foam formation. The properties of these sticky materials can be tailored by virtue of the formulation flexibility; thus, they represent a new class of nontoxic, nonflammable deterrents with a wide temperature range of use.

Two new and related true-triaxial apparatus are described that make use of conventional triaxial pressure vessles in combination with specially configured, high-pressure hydraulic jacks inside these vessels. The development combines advantages not found in existing facilities, including a compact design, pore-pressure and flow-through capabilities, the ability to attain high principal stresses and principal stress differences, direct access to parts of the sample, and provisions to go to relatively large deformations without developing serious stress field inhomogeneities.

The first sinkhole at the Weeks Island Strategic Petroleum Reserve (SPR) site was initially observed in May 1992. Concurrent with the increasing dissolution of salt over the mined oil storage area below, it has gradually enlarged and deepened. Beginning in 1994 and continuing to the present, the injection of saturated brine directly into the sinkhole throat some 76 m beneath the ground surface essentially arrested further dissolution, providing time to make adequate preparation for the safe and orderly transfer of crude oil to other storage facilities. This mitigation measure marked the first time that such a control procedure has been used in salt mining; previously all control has been achieved by either in-mine or from-surface grouting. A second and much smaller sinkhole was noticed in early 1995 on an opposite edge of the SPR mine, but with a very similar geological and mine mechanics setting. Both sinkholes occur where the edges of upper 152 m and lower 213 m mined storage levels are nearly vertically aligned. Such coincidence maximizes the tensional stress development, leading to fracturing in the salt. This cracking takes 20 or more years to develop. The cracks then become flow paths for brine incursion, which after time progress into the mined openings. Undersaturated ground water gradually enlarges the cracks in salt through dissolution, leading to eventual collapse of the overlying sand to form sinkholes. Other geologic conditions may also be secondary factors in controlling both mining extent and sinkhole location.

This paper discusses the design and testing results of a resonant accelerometer developed for integrated surface-micromachining processes.First- and second-generation designs are presented. The sensors use leverage mechanisms to transfer force from a proof mass to double-ended tuning fork (DETF) resonators, used as force transducers. Each fork forms the basis of an integrated oscillator to provide the output waveforms. The DETF`s on the first-generation device have a nominal frequency of 175 kHz, and the sensor has a measured scale factor of 2.4 Hz/g. The oscillators on this device exhibit a root Allan variance floor of 38 mHz (220 ppb). The second-generation, higher-sensitivity sensor uses DETF`s with a nominal frequency of 68 kHz and has measured a scale factor of 45 Hz/g.

Transient power supply voltage (V{sub DDT}) analysis is a new testing technique demonstrated as a powerful alternative and complement to I{sub DDQ} testing. V{sub DDT} takes advantage of the limited response time of a voltage supply to the changing power demands of an IC during operation. Changes in the V{sub DD} response time are used to detect increases in power demand with resolutions of 100 nA at 100 kHz, 1 {mu}A at 1 MHz, and 2.5 {mu}A at 1.5 MHz. These current sensitivities have been shown for ICs with quiescent currents < 0.1 {mu}A and > 300 {mu}A. The V{sub DDT} signal acquisition protocols, frequency versus sensitivity tradeoffs, hardware considerations and limitations, data examples, and areas for future research are described.

A historical perspective is given for Sandia National Laboratories from its beginnings as a small engineering group at an offshoot of Los Alamos Laboratory to a facility of 7000 people at its main facility in Albuquerque, another 1000 people in Livermore, California and test ranges in Tonopah, Nevada and Kauai, Hawaii. The Sandia army base became the Z division of Los Alamos and $25 million construction program began the structures that would carry out a test program for nuclear weapons during the cold war. Bell System/AT&T stewardship of the site continued from 1949 to 1993, when Martin Marietta (now Lockheed Martin) was chosen as the new contractor. Management decisions, personnel, and political aspects of the Laboratory are presented up to 1997 and forecasts are given for future policy and programs of Sandia.

This paper presents the construction of the smart pixel arrays which perform AND and XOR functions with three-input and one-output optical signals for the application of an optical database filter. The device is based on oxide confined VCSELs bump bonded to GaAs MESFET pixels. The MSM photodetectors are monolithically integrated with MESFETs.

The need for collision detection arises in several robotics areas, including motion-planning, online collision avoidance, and simulation. At the heart of most current methods are algorithms for interference detection and/or distance computation. A few recent algorithms and implementations are very fast, but to use them for accurate collision detection, very small step sizes can be necessary, reducing their effective efficiency. We present a fast, implemented technique for doing exact distance computation and interference detection for translationally-swept bodies. For rotationally swept bodies, we adapt this technique to improve accuracy, for any given step size, in distance computation and interference detection. We present preliminary experiments that show that the combination of basic and swept-body calculations holds much promise for faster accurate collision detection.

This paper describes the initial results of one portion of a project to develop effective analytical tools for predicting the effect of atmospheric corrosion on the reliability of electronic devices. The specific objectives of this work were to experimentally characterize the atmospheric corrosion of aluminum-gold wirebonds and to develop a statistical-based model that describes the effect of the resulting stochastic process on the reliability of a selected electronic assembly. The experimental characterization included an attempt at accelerated aging. Modeling involved: (1) the development and validation of empirical models that describe the effects of environmental parameters on corrosion rate, and (2) the formulation and validation of a reliability-prediction model using the accelerated aging data and long-term field information as it becomes available. A preliminary assessment of the effect of three environmental factors on wirebond failure rate was performed and an empirical rate model defined. Subsequently, a statistical treatment of the rate information was used in a Monte Carlo simulation technique to determine the service life of a hypothetical electronic assembly. This work demonstrated that stochastic, corrosion-induced degradation can be successfully incorporated in classical techniques to analyze component reliability. 19 figs., 3 tabs.

A 3-D non-linear electromagnetic inversion scheme has been developed to produce images of subsurface conductivity structure from electromagnetic geophysical data. The solution is obtained by successive linearized model updates where full forward modeling is employed at each iteration to compute model sensitivities and predicted data. Regularization is applied to the problem to provide stability. Because the inverse part of the problem requires the solution of 10`s to 100`s of thousands of unknowns, and because each inverse iteration requires many forward models to be computed, the code has been implemented on massively parallel computer platforms. The use of the inversion code to image environmental sites is demonstrated on a data set collected with the Apex Parametrics {open_quote}MaxMin I-8S{close_quote} over a section of stacked barrels and metal filled boxes at the Idaho National Laboratory`s {open_quote}Cold Test Pit{close_quote}. The MaxMin is a loop-loop frequency domain system which operates from 440 Hz up to 56 kHz using various coil separations; for this survey coil separations of 15, 30 and 60 feet were employed. The out-of phase data are shown to be of very good quality while the in-phase are rather noisy due to slight mispositioning errors, which cause improper cancellation of the primary free space field in the receiver. Weighting the data appropriately by the estimated noise and applying the inversion scheme is demonstrated to better define the structure of the pit. In addition, comparisons are given for single coil separations and multiple separations to show the benefits of using multiple offset data.

A doped-channel heterostructure field effect transistor (H-FET) technology has been developed with self-aligned refractory gate processing and using both enhancement- and depletion-mode transistors. D-HFET devices are obtained with a threshold voltage adjust implant into material designed for E-HFET operation. Both E- and D-HFETs utilize W/WSi bilayer gates, sidewall spacers, and rapid thermal annealing for controlling short channel effects. The 0.5 {mu}m E- HFETs (D-HFETs) have been demonstrated with transconductance of 425 mS/mm (265-310 mS/mm) and f{sub t} of 45-50 GHz. Ring oscillator gate delays of 19 ps with a power of 0.6 mW have been demonstrated using direct coupled FET logic. These results are comparable to previous doped-channel HFET devices and circuits fabricated by selective reactive ion etching rather than ion implantation for threshold voltage adjustment.

The Federal Aviation Administration Airworthiness Assurance Nondestructive Inspection Validation Center (FAA-AANC) and Boeing Commercial Airplane Group are currently developing a study pertaining to the detection of cracks in multi-layered aluminum sheets. The specimen panels model pertinent aspects of the lap splice joints for Boeing 737 aircraft, Line Numbers 292 - 2565. Upon initial characterization of the specimen panels, it became clear that signals produced from a sliding probe at fastener sites were not representative of an in-service lap splice, and therefore, could not be used in a probability of detection experiment. This paper discusses specimen characterization and steps taken to make the specimens useful for nondestructive technology assessment.

Low-density, microcellular foams prepared from the natural polymers agar and gelatin have been developed for pulsed-power physics experiments. Numerous experiments were supported with foams having densities at or below 10 mg/cm{sup 3}. For some of the experiments, the agar/gelatin foam was uniformly doped with metallic elements using soluble salts. Depending on the method of preparation, cell sizes were typically below 10 microns and for one process were below 1.0 micron.

Inverters are key building blocks of photovoltaic (PV) systems that produce ac power. The balance of systems (BOS) portion of a PV system can account for up to 50% of the system cost, and its reliable operation is essential for a successful PV system. As part of its BOS program, Sandia National Laboratories (SNL) maintains a laboratory wherein accurate electrical measurements of power systems can be made under a variety of conditions. This paper outlines the work that is done in that laboratory.

The ability to monitor and control the depth of a laser weld in real-time is critical in many laser welding applications. Consequently, the authors have investigated the use of an optical method to sense weld depth. Welds were generated on kovar samples, using a pulsed Nd:YAG laser. The sensing method uses digital high-speed photography to measure the velocity of the plume of vaporized metal atoms ejected from the metal surface. An energy balance equation is then used to relate the plume velocity to the size of the weld. Numerical solution of the energy balance equation yielded values for weld depth that were within 8% of the actual measured values.

The use of backscattered X rays to image buried land mines and distinguish between surface and buried features has been well documented. Laboratory imaging experiments, being conducted at Sandia National Laboratories/New Mexico (SNL/NM), have been used to develop preliminary data acquisition hardware and software for an upcoming Advanced Technology Demonstration (ATD). In addition image processing techniques, developed by the Department of Nuclear Engineering at the University of Florida (UF), are utilized. Previous buried land mine imaging studies focused on antitank mines buried in screened sand and have included well defined surface features such as a broad or a small diameter rock. In the present study the authors have examined imaging under a variety of practical environmental conditions. They have successfully imaged antitank mines (ATM) buried in sand and rocky New Mexico (NM) soil. Images have been obtained for bare surfaces as well s for surfaces covered with limestone road coarse base (gravel), snow, water, and native grass. In addition, they have imaged buried ATM and surface antipersonnel (AP) mines covered with debris consisting of various size rocks, a log, and leaves such that no mine was visible to the eye.

A continuously operating, scanning x-ray machine is being developed for landmine detection using backscattered x-rays. The source operates at 130 kV and 650 mA. The x-rays are formed by electrons striking a high Z target. Target shape is an approximate 5 cm wide by 210 cm long racetrack. The electron beam is scanned across this target with electromagnets. There are 105, 1-cm by 1-cm collimators in each leg of the racetrack for a total of 210 collimators. The source is moved in the forward direction(the direction perpendicular to the 210-cm dimension) at 3 mi/h. The forward velocity and collimator spacing are such that a grid of collimated x-rays are projected at normal incidence to the soil. The spacing between the collimators and the ground results in a 2-cm by 2-cm x-ray pixel on the ground. A unique detector arrangement of collimated and uncollimated detectors allows surface features to be recognized and removed, leaving an image of a buried landmine. Another detector monitors the uncollimated x-ray output and is used to normalize the source output. The mine detector is being prepared for an Advanced Technology Demonstration (ATD). The ATD is scheduled for midyear of 1998. The results of the source performance in pre ATD tests will be presented.

Effective utilization of unattended ground sensors (UGSs) in a theater reconnaissance, surveillance, target acquisition, and kill assessment environment requires that a human operator be able to interpret, and collectively assess, the significance of real time data obtained from UGS emplacements over large geographical regions of interest. The products of this UGS data interpretation and assessment activity can then be used in the decision support process for command level evaluation of appropriate courses of action. Advancements in both sensor hardware technology and in software systems and processing technology have enabled the development of practical real time situation assessment capabilities based upon information from unattended ground sensors. A decision support workstation that employs rule-based expert system processing of reports from unattended ground sensors is described. The primary goal of this development activity is to produce a suite of software to track vehicles using data from unattended ground sensors. The situational assessment products from this system have stand-alone utility, but are also intended to provide cueing support for overhead sensors and supplementary feeds to all-source fusion centers. The conceptual framework, developmental architecture, and demonstration field tests of the system are described.

A survey of ohmic contact materials and properties to GaAs, InP, GaN will be presented along with critical issues pertaining to each semiconductor material. Au-based alloys (e.g., GeAuNi for n-type GaAs) are the most commonly used contacts for GaAs and InP materials for both n- and p-type contacts due to the excellent contact resistivity, reliability, and usefulness over a wide range of doping levels. Research into new contacting schemes for these materials has focused on addressing limitations of the conventional Au-alloys in thermal stability, propensity for spiking, poor edge definition, and new approaches for a non-alloyed contact. The alternative contacts to GaAs and InP include alloys with higher temperature stability, contacts based on solid phase regrowth, and contacts that react with the substrate to form lower bandgap semiconductors alloys at the interface. A new area of contact studies is for the wide bandgap group III-Nitride materials. At present, low resistivity ohmic contact to p-type GaN has not been obtained primarily due to the large acceptor ionization energy and the resultant difficulty in achieving high free hole concentrations at room temperature. For n-type GaN, however, significant progress has been reported with reactive Ti-based metalization schemes or the use of graded InGaN layers. The present status of these approaches will be reviewed.

This report summarizes progress from the Laboratory Directed Research and Development (LDRD) program during fiscal year 1996. In addition to a programmatic and financial overview, the report includes progress reports from 259 individual R&D projects in seventeen categories. The general areas of research include: engineered processes and materials; computational and information sciences; microelectronics and photonics; engineering sciences; pulsed power; advanced manufacturing technologies; biomedical engineering; energy and environmental science and technology; advanced information technologies; counterproliferation; advanced transportation; national security technology; electronics technologies; idea exploration and exploitation; production; and science at the interfaces - engineering with atoms.

Nuclear operations have resulted in the accumulation of large quantities of contaminated metallic waste which are stored at various DOE, DOD, and commercial sites under the control of DOE and the Nuclear Regulatory Commission (NRC). This waste will accumulate at an increasing rate as commercial nuclear reactors built in the 1950s reach the end of their projected lives, as existing nuclear powered ships become obsolete or unneeded, and as various weapons plants and fuel processing facilities, such as the gaseous diffusion plants, are dismantled, repaired, or modernized. For example, recent estimates of available Radioactive Scrap Metal (RSM) in the DOE Nuclear Weapons Complex have suggested that as much as 700,000 tons of contaminated 304L stainless steel exist in the gaseous diffusion plants alone. Other high-value metals available in the DOE complex include copper, nickel, and zirconium. Melt processing for the decontamination of radioactive scrap metal has been the subject of much research. A major driving force for this research has been the possibility of reapplication of RSM, which is often very high-grade material containing large quantities of strategic elements. To date, several different single and multi-step melting processes have been proposed and evaluated for use as decontamination or recycling strategies. Each process offers a unique combination of strengths and weaknesses, and ultimately, no single melt processing scheme is optimum for all applications since processes must be evaluated based on the characteristics of the input feed stream and the desired output. This paper describes various melt decontamination processes and briefly reviews their application in developmental studies, full scale technical demonstrations, and industrial operations.

The electromagnetic integrated demonstration (EMID) is a baseline study in electromagnetic (EM) exploration of the shallow subsurface (< 10 m). Eleven distinct EM systems, covering the geophysical spectrum, acquired data on a grid over the Idaho National Engineering Laboratory (INEL) Cold Test Pit (CTP). The systems are investigated and evaluated for the purpose of identifying and reviewing existing geophysical characterization instrumentation (commercial and experimental), integrating those technologies with multi-dimensional interpretational algorithms, and identifying gaps in shallow subsurface EM imaging technology. The EMID data, are valuable for testing and evaluating new interpretational software, and developing techniques for integrating multiple datasets. The experimental field techniques shows how the acquisition of data in a variety of array configurations can considerably enhance interpretation. All data are available on the world wide web. Educators and students are encouraged to use the data for both classroom and graduate studies. The purpose of this paper is to explain why, where, how and what kind of data were collected. It is left to the reader to assess the value of a given system for their particular application. Information about the EMID is organized into two general categories: survey description and system evaluation.

Intelligent Systems are characterized by the intensive use of computer power. The computer revolution of the last few years is what has made possible the development of the first generation of Intelligent Systems. Software for second generation Intelligent Systems will be more complex and will require more powerful computing engines in order to meet real-time constraints imposed by new robots, sensors, and applications. A multiprocessor architecture was developed that merges the advantages of message-passing and shared-memory structures: expendability and real-time compliance. The HyperForest architecture will provide an expandable real-time computing platform for computationally intensive Intelligent Systems and open the doors for the application of these systems to more complex tasks in environmental restoration and cleanup projects, flexible manufacturing systems, and DOE`s own production and disassembly activities.

Linear chemometric algorithms were used to model the quantitative response of an evanescent fiber optic chemical sensor in aqueous mixtures with concentrations between 20 and 300 ppm. Four data sets were examined with two different experimental arrangements. Two data sets contained trichloroethene, 1,1,2 trichloroethane, and toluene. Partial Least Squares, PLS, and Principal Component Regression, PCR, algorithms performed comparably on these calibration sets with cross-validated root mean squared errors of prediction (RMSEP) for trichloroethene, 1,1,1 trichloroethane, and toluene of approximately 26, 29 and 22 ppm, respectively. The third data set contained trichloroethene, 1,1,2 trichloroethane, toluene, and chloroform and the fourth contained these four analytes as well as tetrachloroethene. Again, both chemometric algorithms performed comparably on a given data set with RMSEP for trichloroethene, 1,1,2 trichloroethane, toluene, and chloroform of approximately 6, 6, 9, and 16 ppm from the first set, and 7, 11, 13, and 31 ppm from the second set with tetrachloroethene RMSEP of 31 ppm. The decrease in the quantitative performance of the sensor for modeling toluene and chloroform upon addition of tetrachloroethene to the sample solutions is due to increased cladding absorption features in the spectral response matrix. These features overlap with the analyte absorption features of toluene and chloroform. These results suggest one of the limitations with this type of sensing format.

To insert high-performance oxide-confined vertical-cavity surface- emitting lasers (VCSELs) into the manufacturing arena, we have examined the critical parameters that must be controlled to establish a repeatable and uniform wet thermal oxidation process for AlGaAs. These parameters include the AlAs mole fraction, sample temperature, carrier gas flow, and bubbler water temperature. Knowledge of these parameters has enable the compilation of oxidation rate data for AlGaAs which exhibits an Arrhenius rate dependence. The compositionally dependent activation energies for Al{sub x}Ga{sub 1-x}As layers of x=1.00, 0.98, and 0.92 are found to be 1.24, 1.75, and 1.88 eV, respectively. 7 figs, 1 tab, 14 refs.

The authors consider the problem of defining the fracture permeability tensor for each grid lock in a rock mass from maps of natural fractures. For this purpose they implement a statistical model of cracked rock due to M. Oda [1985], where the permeability tensor is related to the crack geometry via a volume average of the contribution from each crack in the population. In this model tectonic stress is implicitly coupled to fluid flow through an assumed relationship between crack aperture and normal stress across the crack. The authors have included the following enhancements to the basic model: (1) a realistic model of crack closure under stress has been added along with the provision to apply tectonic stresses to the fracture system in any orientation, the application of stress results in fracture closure and consequently a reduction in permeability; (2) the fracture permeability can be superimposed onto an arbitrary anisotropic matrix permeability; (3) the fracture surfaces are allowed to slide under the application of shear stress, causing fractures to dilate and result in a permeability increase. Through an example, the authors demonstrate that significant changes in permeability magnitudes and orientations are possible when tectonic stress is applied to a fracture system.

This report is a collection of studies performed at Sandia National Laboratories in support of Phase One (inert debris) for the Risk and Lethality Commonality Team. This team was created by the Range Safety Group of the Range Commander`s Council to evaluate the safety issues for debris generated during flight tests and to develop debris safety criteria that can be adopted by the national ranges. Physiological data on the effects of debris impacts on people are presented. Log-normal curves are developed to relate the impact kinetic energy of fragments to the probability of fatality for people exposed in standing, sitting, or prone positions. Debris hazards to aircraft resulting from engine ingestion or penetration of a structure or windshield are discussed. The smallest mass fragments of aluminum, steel, and tungsten that may be hazardous to current aircraft are defined. Fragment penetration of the deck of a small ship or a pleasure craft is also considered. The smallest mass fragments of aluminum, steel, or tungsten that can penetrate decks are calculated.

In this study the authors employed the Monte Carlo/Latin Hypercube sampling technique to generate input parameters for a liquid polymeric-film drying model with prescribed uncertainty distributions. The one-dimensional drying model employed in this study was that developed by Cairncross et al. They found that the non-deterministic analysis with Monte Carlo/Latin Hypercube sampling provides a useful tool for characterizing the two responses (residual solvent volume and the maximum solvent partial vapor pressure) of a liquid polymeric-film drying process. More precisely, they found that the non-deterministic analysis via Monte Carlo/Latin Hypercube sampling not only provides estimates of statistical variations of the response variables but also yields more realistic estimates of mean values, which can differ significantly from those calculated using deterministic simulation. For input-parameter uncertainties in the range from 2 to 10% of their respective means, variations of response variables were found to be comparable to the mean values.

Sacrificial polysilicon surface micromachining is emerging as a technology that enables the mass production of complex microelectromechanical systems by themselves or integrated with microelectronic systems. Early versions of these micromachined systems-on-a-chip have already found application in the commercial world as acceleration sensors for airbag deployment (for example, ADI`s ADXL50). Two technologies described here, enable systems with increasing degrees of complexity to be fabricated. The first is a three-level polysilicon micromachining process which includes a fourth polysilicon electrical interconnect level, while the other is a single-level (+ second electrical interconnect level) polysilicon surface micromachining process integrated with 1.25 micron CMOS. Samples of systems-on-a-chip built in these processes such as combination locks, pop-up mirrors, and multi-axis accelerometers are also given.

Smaller, lighter instruments can be fabricated as Micro-Electro-Mechanical Systems (MEMS), having micron scale moving parts packaged together with associated control and measurement electronics. Batch fabrication of these devices will make economical applications such as condition-based machine maintenance and remote sensing. The choice of instrumentation is limited only by the designer`s imagination. This paper presents one genre of MEMS fabrication, surface-micromachined polycrystalline silicon (polysilicon). Two currently available but slightly different polysilicon processes are presented. One is the ARPA-sponsored ``Multi-User MEMS ProcesS`` (MUMPS), available commercially through MCNC; the other is the Sandia National Laboratories ``Sandia Ultra-planar Multilevel MEMS Technology`` (SUMMiT). Example components created in both processes will be presented, with an emphasis on actuators, actuator force testing instruments, and incorporating actuators into larger instruments.

In the present study of design optimization of a liquid-distribution chamber-slot die, the DAKOTA (Design Analysis Kit for OpTimizAtion) toolkit, which is being developed by Sandia National Laboratories, was employed to navigate the search for the optimal die shape. This shape minimizes non-uniformity of flow at the slot exit for a given set of liquid properties and operating conditions. Three-dimensional, steady newtonian-liquid flow fields inside the chamber-slot die were computed using FIDAP, a commercial computer code based on the finite element method. The objective function of flow nonuniformity at the slot exit is formulated as the percentage of coating material across the slot width having local-flowrate deviation greater than 1% from the mean. Computation of the objective function requires the integration of the velocity profile over the outflow plane. Two constraints, namely maximum hydrodynamic pressure and average residence time, were imposed in the optimization problem. The modified method of feasible directions algorithm was used to optimize the die geometry and to reduce the flow nonuniformity at the slot exit from 16.5% (initial design) to 3.2% (final design) for the chosen liquid properties and process conditions. The case study demonstrates that liquid-distribution chamber-slot dies can be systematically optimized using DAKOTA.