Publications

Cooperative monitoring holds the promise of utilizing many technologies from conflicts of the past to implement agreements of peace in the future. Important approaches to accomplish this are to develop the framework for assessing monitoring opportunities and to provide education and training on the technologies and experience available for sharing with others. The Cooperative Monitoring Center (CMC) at Sandia National Laboratories is working closely with agencies throughout the federal government, academics at home and abroad, and regional organizations to provide the technical tools needed to assess, design, analyze, and implement these cooperative agreements. In doing so, the goals of building regional confidence and increasing trust and communication can be furthered.

Several techniques to predict pad failure during tungsten CMP were investigated for a specific consumable set. These techniques include blanket polish rate measurements and metrics derived from two endpoint detection schemes. Blanket polish rate decreased significantly near pad failure. Metrics from the thermal endpoint technique included change in peak temperature, change in the time to reach peak temperature, and the change in the slope of the temperature trace just prior to peak temperature all as a function of pad life. Average carrier motor current before endpoint was also investigated. Changes in these metrics were observed however these changes, excluding time to peak process temperature, were either not consistent between pads or too noisy to be reliable predictors of pad failure.

This paper details the analysis of vibration monitoring for end-point control in oxide CMP processes. Two piezoelectric accelerometers were integrated onto the backside of a stainless steel polishing head of an IPEC 472 polisher. One sensor was placed perpendicular to the carrier plate (vertical) and the other parallel to the plate (horizontal). Wafers patterned with metal and coated with oxide material were polished at different speeds and pressures. Our results show that it is possible to sense a change in the vibration signal over time during planarization of oxide material on patterned wafers. The horizontal accelerometer showed more sensitivity to change in vibration amplitude compared to the vertical accelerometer for a given polish condition. At low carrier and platen rotation rates, the change in vibration signal over time at fixed frequencies decreased approximately ½ - 1 order of magnitude (over the 2 to 10 psi polish pressure ranges). At high rotation speeds, the vibration signal remained essentially constant indicating that other factors dominated the vibration signaL These results show that while it is possible to sense changes in acceleration during polishing, more robust hardware and signal processing algorithms are required to ensure its use over a wide range of process conditions.

Abstract not provided.

Casing deformation in wells is a common problem in many geothermal fields. Casing remediation is necessary to keep wells in production and occasionally, to even enter the well for an approved plug and abandonment procedure. The costly alternative to casing remediation is to incur the expense of drilling a new well to maintain production or drilling a well to intersect a badly damaged well below the deformation for abandonment purposes. The U.S. Department of Energy and the Geothermal Drilling Organization sponsor research and development work at Sandia National Laboratories in an effort to reduce these remediation expenditures. Sandia, in cooperation with Halliburton Energy Services, has developed a low cost, commercially available, bridge-plug-type packer for use in geothermal well environments. This report documents the development and testing of this tool for use in casing remediation work.

Silicon micromachine designs include engines that consist of orthog- onally oriented linear comb drive actuators mechanically connected to a rotating gear. These gears are as small as 50 {micro}m in diameter and can be driven at rotation rates exceeding 300,000 rpm. Generally, these en- gines will run with non-uniform rotation rates if the drive signals are not properly designed and maintained over a range of system parameters. We present a method for producing constant rotation rates in a micro-engine driven by an orthogonal linkage system. We show that provided the val- ues of certain masses, springs, damping factors, and lever arms are in the right proportions, the system behaves as though it were symmetrical. We will refer to systems built in this way as being quasi-symmetrical. We show that if a system is built quasi-symmetrically , then it is possible to achieve constant rotation rates even if one does not know the form of the friction function, or the value of the friction. We analyze this case in some detail.

In this paper we present an approach that facilitates the validation of high consequence system requirements. This approach consists of automatically generating a graphical representation from an informal document. Our choice of a graphical notation is statecharts. We proceed in two steps: we first extract a hierarchical decomposition tree from a textual description, then we draw a graph that models the statechart in a hierarchical fashion. The resulting drawing is an effective requirements assessment tool that allows the end user to easily pinpoint inconsistencies and incompleteness.

We investigate the apparent charge transfer between adatoms in the GeXPb[l.XjGe(lll) interface both experimentally and theoretically. Scanning tunneling microscopy and surface core level measurements suggest significant charge transfer from the Ge adatoms to the Pb adatoms. However, first-principles calculations unambiguously find that the total electronic displacement is negligibly small, and that the results of published experiments can be explained as a result of bond rearrangement.

Friction force microscopy measurements of a polydiacetylene monolayer film reveal a 300% friction anisotropy that is correlated with the film structure. The film consists of a monolayer of the red form of N-(2-ethanol)- 10,12 pentacosadiynamide, prepared on a Langmuir trough and deposited on a mica substrate. As confirmed by atomic force microscopy and fluorescence microscopy, the monolayer consists of domains of linearly oriented conjugated backbones with pendant hydrocarbon side chains above and below the backbones. Maximum friction occurs when the sliding direction is perpendicular to the backbone. We propose that the backbones impose anisotropic packing of the hydrocarbon side chains which leads to the observed friction anisotropy. Friction anisotropy is therefore a sensitive, optically-independent indicator of polymer backbone direction and monolayer structural properties.

Abstract not provided.

We have synthesized the Z and E isomers of 1,4-bis(triethoxysilyl)-2- butene and polymerized them under acid and base catalyzed sol-gel conditions. As expected the E system formed crosslinked, insoluble gels. The Z isomer, by nature of its geometry, formed high molecular weight, soluble polymeric products under acidic conditions. We were able to prepare and isolate both the cyclic disilsesquioxane monomer, and its dimer. Comparison of their spectral characterization with that of the soluble polymers suggests that the cyclics are present within the polymers. lle synthesis of a dimer likely present at some early stage of the polymerization suggests that we may be able to control the reaction and form rigid polymers with controllable tacticity. In addition, most of the gels were found to be non-porous indicating that the gels were, in fact, more compliant than ethenylene-bridged polysilsesquioxanes leading to collapse of pores during drying.

The detection of mines, both during and after hostilities, is a growing international problem. It limits military operations during wartime and unrecovered mines create tragic consequences for civilians. From a purely humanitarian standpoint an estimated 100 million or more unrecovered mines are located in over 60 countries worldwide. This paper presents an overview of some of the technologies currently being investigated by Sandia National Laboratories for the detection and monitoring of minefields in land and water environments. The three technical areas described in this paper are: 1) the development of new mathematical techniques for combining or fusing the data from multiple sources for enhanced decision-making; 2) an environmental fate and transport (EF&T) analysis approach that is central to improving trace chemical sensing technique; and 3) the investigation of an underwater range imaging device to aid in locating and characterizing mines and other obstacles in coastal waters.

In the scanning electron microscope (SEM), using electron backscattered diffraction (EBSD), it is possible to measure the spacing of the layers in the reciprocal lattice. These values are of great use in confirming the identification of phases. The technique derives the layer spacing from the HOLZ rings which appear in patterns from many materials. The method adapts results from convergent-beam electron diffraction (CBED) in the transmission electron microscope (TEM). For many materials the measured layer spacing compares well with the calculated layer spacing. A noted exception is for higher atomic number materials. In these cases an extrapolation procedure is described that requires layer spacing measurements at a range of accelerating voltages. This procedure is shown to improves the accuracy of the technique significantly. The application of layer spacing measurements in EBSD is shown to be of use for the analysis of two polytypes of SiC.

Our vision of the future of information systems is one that includes engineered collectives of software agents which are situated in an environment over years and which increasingly improve the performance of the overall system of which they are a part. At a minimum, the movement of agent and multi-agent technology into National Security applications, including their use in information assurance, is apparent today. The use of deliberative, autonomous agents in high-consequence/high-security applications will require a commensurate level of protection and confidence in the predictability of system-level behavior. At Sandia National Laboratories, we have defined and are addressing a research agenda that integrates the surety (safety, security, and reliability) into agent-based systems at a deep level. Surety is addressed at multiple levels: The integrity of individual agents must be protected by addressing potential failure modes and vulnerabilities to malevolent threats. Providing for the surety of the collective requires attention to communications surety issues and mechanisms for identifying and working with trusted collaborators. At the highest level, using agent-based collectives within a large-scale distributed system requires the development of principled design methods to deliver the desired emergent performance or surety characteristics. This position paper will outline the research directions underway at Sandia, will discuss relevant work being performed elsewhere, and will report progress to date toward assurance in agent-based systems.

The solution-mediated syntheses and single crystal structures of (CH₃NH₃)₃·Zn₄0(AsO₄)₃ and (CH₃NH₃)₃·Zn₄O(P0₄)₃ are reported. These compounds are built up from vertex-sharing three-dimensional Zn0₄ + AsO₄/P0₄ tetrahedral frameworks encapsulating methylammonium cations in three-dimensional channel systems. These phases are closely related to the zeolite- like M₃Zn₄O(XO₄)₃·nH₂O family of phases. Crystal data for (CH₃NH₃)₃·Zn₄0(AsO₄)₃, M, = 790.47, monoclinic, space group P2₁ (No. 4), a = 7.814 (3)Å, b = 15.498 (6)Å, c = 7.815 (3) Å, {beta} = 92.91 (2)0, V = 945.1 (9) ų, Z = 2, R(F) = 3.01%, R_W(F) = 3.98% (2301 reflections, 236 parameters). Crystal data for (CH₃NH₃)₃·Zn₄0(P0₄)₃: M, = 658.63, monoclinic, space group P2₁ (No. 4), a = 7.6569 (5) Å, b = 15.241 (1)Å, c= 7.6589 (5) Å, {beta} = 92.740 (1)0, V= 892.7 (5) ų, Z = 2, R(F)= 8.07%, R_W(F)= 9.60% (2694 reflections, 106 parameters).

Zeolite W has been synthesized using organometallic silicon and aluminum precursors in two hydrothermal systems: organocation containing and organocation-free. The reaction using the organocation yielded a fully crystalline, relatively uniform crystal size product, with no organic molecules occluded in the pores. In contrast, the product obtained from an identical reaction, except for the absence of the organocation, contained amorphous as well as crystalline material and the crystalline phase showed a large diversity of both crystal size and morphology. The use of organometallic precursors, either with or without an organocation, allows for the crystallization of the MER framework at much lower 0H/Si02 and (K+ Na - Al)/Si ratios than is typical of inorganic systems. The reaction products were characterized by XRD, SEM, EDS, and thermal analyses.

The solution-mediated syntheses and single crystal structures of (N₂C₆H₁₄)·Zn(HPO₄)₂·H₂O (I), H₃N(CH₂)₃NH₃·Zn₂(HPO₄)₃ (II), and (N₂C₆H₁₄)·Zn₃(HPO₄)₄ (III) are described. These phases contain vertex-sharing Zn0₄ and HP0₄ tetrahedra, accompanied by doubly- protonated organic cations. Despite their formal chemical relationship, as members of the series of t·Zn_n(HP0₄)_n+1 (t= template, n = 1-3), these phases adopt fimdamentally different crystal structures, as one-dimensional, two-dimensional, and three-dimensional Zn0₄/HP0₄ networks, for I, II, and III respectively. Similarities and differences to some other zinc phosphates are briefly discussed. Crystal data: (N₂C₆H₁₄)·Zn(HP0₄)₂·H₂0, M_r = 389.54, monoclinic, space group P2₁/n (No. 14), a = 9.864 (4) Å, b = 8.679 (4) Å, c = 15.780 (3) Å, β = 106.86 (2)°, V= 1294.2 (8) ų, Z = 4, R(F) = 4.58%, R_W(F) = 5.28% [1055 reflections with I >3σ(I)]. H₃N(CH₂)₃NH₃·Zn₂(HP0₄)₃, M_r = 494.84, monoclinic, space group P2₁/c (No. 14), a= 8.593 (2)Å, b= 9.602 (2)Å, c= 17.001 (3)Å, β= 93.571 (8)°, V = 1400.0 (5) ų, Z = 4, R(F) = 4.09%, R_W(F) = 4.81% [2794 reflections with I > 3σ (I)]. (N₂C₆H₁₄)·Zn₃(HP0₄)₄, M_r= 694.25, monoclinic, space group P2₁/n (No. 14), a = 9.535 (2) Å, b = 23.246 (4)Å, c= 9.587 (2)Å, β= 117.74 (2)°, V= 1880.8 (8) ų, Z = 4, R(F) = 3.23%, R_W(F) = 3.89% [4255 reflections with 1> 3σ(I)].

Due to the vast diversity of chemical media in which metal separations are executed, a wide range of ion separation materials are employed. This results in an ongoing effort to discover new phases with novel ion exchange properties. We present here the synthesis of a novel class of thermally and chemically stable microporous, niobate-based materials. Ion exchange studies show these new phases are highly selective for Sr²⁺ and other bivalent metals.

Silica nanoparticles exhibiting hexagonal, cubic, and vesicular mesostructures have been prepared using aerosol assisted, self-assembled process. This process begins with homogennous aerosol droplets containing silica source, water, ethanol, and surfactant, in which surfactant concentration is far below the critical micelle concentration (cmc). Solvent evaporation enriches silica and surfactant inducing interfacial self-assembly confined to a spherical aerosol droplet and results in formation of completely solid, ordered spherical particles with stable hexagonal, cubic, or vesicular mesostructures.

Understanding of single and multi-phase flow and transport in fractures can be greatly enhanced through experimentation in transparent systems (analogs or replicas) where light transmission techniques yield quantitative measurements of aperture, solute concentration, and phase saturation fields. Here we quanti@ aperture field measurement error and demonstrate the influence of this error on the results of flow and transport simulations (hypothesized experimental results) through saturated and partially saturated fractures. find that precision and accuracy can be balanced to greatly improve the technique and We present a measurement protocol to obtain a minimum error field. Simulation results show an increased sensitivity to error as we move from flow to transport and from saturated to partially saturated conditions. Significant sensitivity under partially saturated conditions results in differences in channeling and multiple-peaked breakthrough curves. These results emphasize the critical importance of defining and minimizing error for studies of flow and transpoti in single fractures.

An investigation of the synthesis of novel dodecaarylporphyrins using the Suzuki coupling reaction of arylboronic acids with octabromotetraarylporphyrins is reported. Studies of the dynamic properties of these new porphyrins using variable temperature (VT) ¹H NMR spectroscopy and molecular mechanics provide interesting insights into their dynamic properties, including the first determination of {beta} aryl rotation in a porphyrin system.

The time evolution of the amplitude of periodic nanoscale ripple patterns formed on Ar+ sputtered Si(OOl ) surfaces was examined using a recently developed in situ spectroscopic technique. At sufficiently long times, we find that the amplitude does not continue to grow exponentially as predicted by the standard Bradley-Harper sputter rippling model. In accounting for this discrepancy, we rule out effects related to the concentration of mobile species, high surface curvature, surface energy anisotropy, and ion-surface interactions. We observe that for all wavelengths the amplitude ceases to grow when the width of the topmost terrace of the ripples is reduced to approximately 25 nm. This observation suggests that a short circuit relaxation mechanism limits amplitude . growth. A strategy for influencing the ultimate ripple amplitude is discussed.

Optimal selection of array sensors for a chemical sensing application is a nontrivial task. It is commonly believed that "more is better" when choosing the number of sensors required to achieve good chemical selectivity. However, cost and system complexity issues point towards the choice of small arrays. A quantitative array optimization is carried out to explore the selectivity of arrays of partially-selective chemical sensors as a function of array size. It is shown that modest numbers (dozens) of target analytes are completely distinguished with a range of arrays sizes. However, the array selectivity and the robustness against sensor sensitivity variability are significantly degraded if the array size is increased above a certain number of sensors, so that relatively small arrays provide the best performance. The results also suggest that data analyses for very large arrays of partially-selective sensors will be optimized by separately anal yzing small sensor subsets.

Controlled impact experiments have been performed to determine the spall strength of four different concrete compositions. The four concrete compositions are identified as, `SAC-5, CSPC', ("3/4") large, and ("3/8") small, Aggregate. They differ primarily in aggregate size but with average densities varying by less than five percent. Wave profiles from sixteen experiments, with shock amplitudes of 0.07 to 0.55 GPa, concentrate primarily within the elastic regime. Free-surface particle velocity measurements indicate consistent pullback signals in the release profiles, denoting average span strength of approximately 40 MPa. It is the purpose of this paper to present spall measurements under uniaxial strain loading. Notwithstanding considerable wave structure that is a unique characteristic to the heterogeneous nature of the scaled concrete, the spall amplitudes appear reproducible and consistent over the pressure range reported in this study.

This paper summarizes the current status of the treatment of human reliability in fire risk analyses for nuclear power plants and identifies areas that need to be addressed. A new approach is suggested to improve the modeling.

Many hazardous material handling needs exist in remote unstructured environments. Currently these operations are accomplished using personnel in direct contact with the hazards. A safe and cost effective alternative to this approach is the use of intelligent robotic systems for safe handling, packaging, transport, and even excavation of hazardous materials. The Intelligent Systems and Robotics Center of Sandia National Laboratories has developed and deployed robotic technologies for use in hazardous environments, three of which have been deployed in DOE production facilities for handling of special nuclear materials. Other systems are currently under development for packaging special nuclear materials. This paper presents an overview of the research activities, including five delivered systems, at %ndia National Laboratories on the use of robotics in hazardous environments.

Thermal instabilities were identified in SONY-type lithium-ion cells and correlated with interactions of cell constituents and reaction products. Three temperature regions of interaction were identified and associated with the state of charge (degree of Li intercalation) of the cell. Anodes were shown to undergo exothermic reactions as low as 100°C involving the solid electrolyte interface (SEI) layer and the LiPF₆ salt in the electrolyte (EC: PC: DEC/LiPF₆). These reactions could account for the thermal runaway observed in these cells beginning at 100°C. Exothermic reactions were also observed in the 200°C-300°C region between the intercalated lithium anodes, the LiPF₆ salt and the PVDF. These reactions were followed by a high- temperature reaction region, 300°C-400°C, also involving the PVDF binder and the intercalated lithium anodes. The solvent was not directly involved in these reactions but served as a moderator and transport medhun. Cathode exotherrnic reactions with the PVDF binder were observed above 200oC and increased with the state of charge (decreasing Li content). This offers an explanation for the observed lower thermal runaway temperatures for charged cells.

This paper reports progress on implementing a new capability of adaptive mesh refinement into the Eulerian multimaterial shock- physics code CTH. The adaptivity is block-based with refinement and unrefinement occurring in an isotropic 2:1 manner. The code is designed to run on serial, multiprocessor and massive parallel platforms. An approximate factor of three in memory and performance improvements over comparable resolution non-adaptive calculations has-been demonstrated for a number of problems.

The nucleation of GaN thin films on GaAs is investigated for growth at 620 "C. An rf plasma cell is used to generate chemically active nitrogen from N₂. An arsenic flux is used in the first eight monolayer of nitride growth to enhance nucleation of the cubic phase. Subsequent growth does not require an As flux to preserve the cubic phase. The nucleation of smooth interfaces and GaN films with low stacking fault densities is dependent upon relative concentrations of active nitrogen species in the plasma and on the nitrogen to gallium flux ratio.

A management system approach for evaluating environment, safety, health, and quality is in use at Sandia National Laboratories (SNL). Sandia is a multiprogram laboratory operated by Sandia Corporation, a Lockheed Martin Company, for the United States Department of Energy under contract DE-AC04-94AL85000. As a multi-program national laboratory, SNL has many diverse operations including research, engineering development and applications, production, and central services supporting all activities and operations. Basic research examples include fusion power generation, nuclear reactor experiments, and investigation of combustion processes. Engineering development examples are design, testing, and prototype developments of micro-mechanical systems for safe'~arding computer systems, air bags for automobiles, satellite systems, design of transportation systems for nuclear materials, and systems for use in medical applications such as diagnostics and surgery. Production operations include manufacture of instrumented detection devices, radioisotopes, and replacement parts for previously produced engineered systems. Support services include facilities engineering, construction, and site management, site security, packaging and transportation of hazardous materials wastes, ES&H functional programs to establish requirements and guidance to comply with federal, state, local, and contractual requirements and work safety. In this diverse environment, unlike more traditional single function business units, an integrated consistent management system is not typical. Instead, each type of diverse activity has its own management system designed and distributed around the operations, personnel, customers, and facilities (e.g., hazards involved, security, regulatory requirements, and locations). Laboratory managers are not likely to have experience in the more traditional hierarchical or command and control structures and thus do not share oversight expectations found in centralized management systems. The resulting corporate management system gives the appearance of an assembly of multiple, nearly independent operating units. The executive management system maintains these separate units, encouraging autonomy and creativity by establishing a minimum of requirements and procedures. In any organization, senior management has a responsibility to ensure that all operating units are meeting requirements. Part of this responsibility is fulfilled by conducting oversight or assurance activities, to determine the effectiveness of established systems in meeting requirements and performance expectations. Internal independent assessment is one of these assurance activities. Independent appraisals are combined with external audits and appraisals, self-assessments, peer reviews, project reviews, and other internal and external audits (e.g., financial, contractual) for a more complete assurance view. At SNL, internal independent appraisals are performed by the Audit Center, which reports directly to the Executive Vice President. ES&H independent appraisals are the responsibility of the ES&H and Quality Assessments Department, with a staff complement of eight. With our organization's charter to perform internal, independent appraisals, we set out to develop an approach and associated tools, which would be useful in the overall SNL environment and within our resource limitations.

Solid Polymer Electrolytes (SPE) are widely used in batteries and fuel cells because of the high ionic conductivity that can be achieved at room temperature. The ions are usually Li or protons, although other ions can be shown to conduct in these polymer films. There has been very little work on using these films as chemical sensors. We have found that thin films of polymers like polyethyleneoxide (PEO) are very sensitive to low concentrations of volatile organic compounds (VOCS) like common solvents. We will present impedance spectroscopy of PEO films in the frequency range 0.01 Hz to 1 MHz for different concentrations of VOCS. We find that the measurement frequency is important for distinguishing ionic conductivity from the double layer capacitance and parasitic capacitances.

A procedure has been developed to represent the loading on a penetrator and its motion during oblique penetration into geologic media. The penetrator is modeled with the explicit dynamics, finite element computer program PRONTO 3D and the coupled pressure on the penetrator is given in a new loading option based on a separate cavity expansion (CE) solution that accounts for the pressure-reduction from a nearby target free surface. The free-surface influ- ence distance is selected in a predictive manner by considering the pressure to expand a spherical cavity in a finite radius sphere of the target material. The CE/PRONTO 3D procedure allows a detailed description of the penetrator for predicting shock environments or structural failure dur- ing the entire penetration event and is sufficiently rapid to be used in design optimization. It has been evaluated by comparing its results with data from two field tests of a full-scale penetrator into frozen soil at an impact angles of 49.6 and 52.5 degrees from the horizontal. The measured penetrator rotations were 24 and 22 degrees, respectively. In the simulation, the rotation was21 degrees and predominately resulted from the pressure reduction of the free surface. Good agree- ment was also found for the penetration depth and axial and lateral acceleration at two locations in the penetrator.

Chemical Equilibrium calculations are presented that are relevant to the purification of molten silicon by gas-blowing. The equilibrium distributions of silicon, boron, phosphorus carbon and iron among the solid, liquid and gas phases are reported for a variety of added chemicals, temperatures and total pressures. The identities of the dominant chemical species for each element in each phase are also provided for these conditions. The added gases examined are O(2), air, water, wet air, HCl, Cl(2), Cl(2)/O(2), SiCl(4), NH(3), NH(4)OH, and NH(4)Cl. These calculations suggest possible purification schemes, although kinetic or transport limitations may prove to be significant

Results from a Fire Test with a three-by-three stack of standard 6 m long International Standards Organization shipping containers containing combustible fuels and empty radioactive materials packages are reported and discussed. The stack is intended to simulate fire conditions that could occur during on-deck stowage on container cargo ships. The fire is initated by locating the container stack adjacent to a 9.8 x 6 m pool fire. Temperatures of both cargoes (empty and simulated radioactive materials packages) and containers are recorded and reported. Observations on the duration, intensity and spread of the fire are discussed. Based on the results, models for simulation of fire exposure of radioactive materials packages in such fires are suggested.

As a way to bootstrap the DISCOM(2) Distance Computing Program the SP2 Pilot Project was launched in March 1998. The Pilot was directed towards creating an environment to allow Sandia users to run their applications on the Accelerated Strategic Computing Initiative's (ASCI) Blue Pacific computation platform, the unclassified IBM SP2 platform at Lawrence Livermore National Laboratory (LLNL). The DISCOM(2) Pilot leverages the ASCI PSE (Problem solving Environment) efforts in networking and services to baseline the performance of the current system. Efforts in the following areas of the pilot are documented: applications, services, networking, visualization, and the system model. It details not only the running of two Sandia codes CTH and COYOTE on the Blue Pacific platform, but also the buildong of the Sandia National Laboratories (SNL) proxy environment of the RS6000 platforms to support the Sandia users.

Eigenanalysis is a critical component of structural dynamics which is essential for determinating the vibrational response of systems. This effort addresses the development of numerical algorithms associated with scalable eigensolver techniques suitable for use on massively parallel, distributed memory computers that are capable of solving large scale structural dynamics problems. An iterative Lanczos method was determined to be the best choice for the application. Scalability of the eigenproblem depends on scalability of the underlying linear solver. A multi-level solver (FETI) was selected as most promising for this component. Issues relating to heterogeneous materials, mechanisms and multipoint constraints have been examined, and the linear solver algorithm has been developed to incorporate features that result in a scalable, robust algorithm for practical structural dynamics applications. The resulting tools have been demonstrated on large problems representative of a weapon's system.

Thermal instabilities were identified in SONY-type lithium-ion cells and correlated with interactions of cell constituents and reaction products. Three temperature regions of interaction were identified and associated with the state of charge (degree of Li intercalation) of the cell. Anodes were shown to undergo exothermic reactions as low as 100 degree C involving the solid electrolyte interface (SEI) layer and the LiPF(6) salt in the electrolyte (EC-PC:DEC/IM LiPF(6)). These reactions could account for the thermal runaway observed in these cells beginning at 100 degree C. Exothermic reactions were also observed in the 200 degree C to 300 degree C region between the intercalated lithium anodes, the LiPF(6) salt, and the PVDF. These reactions were followed by a high-temperature reaction region, 300 degree C to 400 degree C, also involving the PVDF binder and the intercalated lithium anodes. The solvent was not directly involved in these reactions but served as a moderator and transport medium. Cathode exothermic reactions with the PVDF binder were observed above 200 degree C and increased with the state of charge (decreasing Li content). The stability of the PVDF binder as a function of electrochemical cycling was studied using FTIR. The infrared spectra from the extracts of both electrodes indicate that PVDF is chemically modified by exposure to the lithium cell electrolyte (as well as electrochemical cycling) in conjunction with NMP extraction. Preconditioning of PVDF to dehydrohalogenation, which may be occurring by reaction with LiPf(6), makes the PVDF susceptible to attack by a range of nucleophiles.

The steady state and transient thermal behavior of an electromigration test structure was analyzed. The test structure was a Sandia SHIELD (Self-stressing HIgh fregquency rELiability Device) electromigration test device manufactured by an outside vendor. This device has a high frequency oscillator circuit, a buffer circuit to isolate and drive the metal line to the tested (DUT), the DUT to be electromigrated itself, a metal resistance thermometry monitor, and a heater elment to temperature accelerate the electromigration effect.

A furnace has been built for the purpose of producing anisotropic porous metals through solid-gas eutectic solidification. This process allows control of continuously formed anisotropic pores in metals and was discovered at the State Metallurgical Academic' University in Dnepropetrovsk Ukraine. The process incorporates hydrogen gas within the metal as it solidifies from the molten state. Metals which do not form hydrides, including iron, nickel, aluminum, copper and others can be formed in this manner. The furnace is housed within a ~.64 meter³ (30 ft³) ASME code stamped cylindrical stainless steel vacuum/pressure vessel. The vessel is a water chilled vertical cylinder with removable covers at the top and bottom. It can be evacuated to 20 mTorr or pressurized to 5.5 MPa (800 psi). A charge of 2700 cc (167 in³) of molten metal can be melted in a crucible in the upper portion within a watercooled 30 cm (12 in.) ID induction coil. A 175 kW Inductotherm power source energizes the coil. Vertical actuation of a ceramic stopper rod allows the molten metal to be tapped into a solidification mold beneath the melting crucible. The cylindrical mold rests on a water cooled copper base inducing directional solidification from the bottom. Mixtures of hydrogen and argon gases are introduced during the process. The system is remotely controlled and located in a structure with frangible walls specially designed for possible ambient pressure excursions as a result of equipment failure. This paper includes a general description of the furnace and operating procedure and a detailed description of the control, monitoring and interlock systems.

We have developed a new multilayer a-tC material that is thick stress-free, adherent, low friction, and with hardness and stiffness near that of diamond. The new a-tC material is deposited by J pulsed-laser deposition (PLD) at room temperature, and fully stress-relieved by a short thermal anneal at 600°C. A thick multilayer is built up by repeated deposition and annealing steps. We measured 88 GPa hardness, 1100 GPa Young's modulus, and 0.1 friction coefficient (under high load). Significantly, these results are all well within the range reported for crystalline diamond. In fact, this material, if considered separate from crystalline diamond, is the 2nd hardest material known to man. Stress-free a-tC also has important advantages over thin film diamond; namely, it is smooth, processed at lower temperature, and can be grown on a much broader range of substrates. This breakthrough will enable a host of applications that we are actively pursuing in MEMs, sensors, LIGA, etc.

The Integrated Fuel-Coolant Interaction Code (IFCI) is a best-estimate computer program for analysis of phenomena related to mixing of molten nuclear reactor core material with reactor coolant (water). The stand-alone version of the code, IFCI 7.0, has been designed for analysis of small- and intermediate-scale experiments in order to gain insight into the physics (including scaling effects) of molten fuel-coolant interactions. The code's methods, models, and correlations are being assessed. This report describes the flow regime, friction factor, and heat-transfer models used in the current version of IFCI (IFCI 7.0).

Object-oriented analysis methods have been used in the computer science arena for a number of years to model the behavior of computer-based systems. This report documents how such methods can be applied to surety analysis. By embodying the causality and behavior of a system in a common object-oriented analysis model, surety analysts can make the assumptions that underlie their models explicit and thus better communicate with system designers. Furthermore, given minor extensions to traditional object-oriented analysis methods, it is possible to automatically derive a wide variety of traditional risk and reliability analysis methods from a single common object model. Automatic model extraction helps ensure consistency among analyses and enables the surety analyst to examine a system from a wider variety of viewpoints in a shorter period of time. Thus it provides a deeper understanding of a system's behaviors and surety requirements. This report documents the underlying philosophy behind the common object model representation, the methods by which such common object models can be constructed, and the rules required to interrogate the common object model for derivation of traditional risk and reliability analysis models. The methodology is demonstrated in an extensive example problem.

The integrated fuel-coolant interaction (IFCI) computer code is being developed at Sandia National Laboratories to investigate the fuel-coolant interaction (FCI) problem at large scale using a two-dimensional, three-field hydrodynamic framework and physically based models. IFCI will be capable of treating all major FCI processes in an integrated manner. This document is a description of IFCI 7.0. The user's manual describes the hydrodynamic method and physical models used in IFCI 7.0. Appendix A is an input manual provided for the creation of working decks.

We have developed a wafer fusion technology to achieve integration of semiconductor materials and heterostructures with widely disparate lattice parameters, electronic properties, and/or optical properties for novel devices not now possible on any one substrate. Using our simple fusion process which uses low temperature (400-600 C) anneals in inert N{sub 2} gas, we have extended the scope of this technology to examine hybrid integration of dissimilar device technologies. As a specific example, we demonstrate wafer bonding vertical cavity surface emitting lasers (VCSELs) to transparent AlGaAs and GaP substrates to fabricate bottom-emitting short wavelength VCSELs. As a baseline fabrication technology applicable to many semiconductor systems, wafer fusion will revolutionize the way we think about possible semiconductor devices, and enable novel device configurations not possible by epitaxial growth.

In this combination background and position paper, the authors argue that careful work is needed to develop accurate methods for relating the results of fine-scale numerical simulations of material processes to meaningful values of macroscopic properties for use in constitutive models suitable for finite element solid mechanics simulations. To provide a definite context for this discussion, the problem is couched in terms of the lack of general objective criteria for identifying the size of the representative volume (RV) of a material. The objective of this report is to lay out at least the beginnings of an approach for applying results and methods from statistical physics to develop concepts and tools necessary for determining the RV size, as well as alternatives to RV volume-averaging for situations in which the RV is unmanageably large. The background necessary to understand the pertinent issues and statistical physics concepts is presented.

This report is a cradle-to-grave fabrication and postmortem analysis of a sodium-filled heat pipe solar receiver. The Stirling Thermal Motors Gen. H engine was tested with the Thermacore, Inc. heat pipe receiver on Sandia's Test Bed Concentrator II in the fall of 1996. Although engine performance was significantly increased relative to a direct insolation version of the receiver, hot spots did develop on the heat pipe receiver dome. Over the course of a couple of weeks, after tests were completed, the sodium was distilled out of this receiver, and the front dome was removed. Several failure spots and/or cracks (dubbed volcanoes ) were present on the surface of the wick. Postmortem analysis indicates that the cracks in the wick of the heat pipe are not a product of corrosive oxide action. Voids formed within the wick (created either by mechanical or thermal means) serve to concentrate phosphorous from the electroless plating into the liquid sodium. The presence of phosphorous has an apparently harmful effect on the wick. Examination of a virgin piece of the nickel wick material treated in the same manner as the bulk, prior to the introduction of sodium, would be the best baseline sample for comparison. This sample could be analyzed for phosphorous migration into the wick and determine if there is any initial crack formation from the sintering process. Utiortunately a sample of this material was not available during the preparation of this report. Continued work to determine the mechanism of crack formation could significantly increase the hours of available lifetime testing for future solar thermal heat pipe receivers

A tutorial is presented discussing the basic issues associated with propagation of uncertainty analysis and statistical validation of engineering and scientific models. The propagation of uncertainty tutorial illustrates the use of the sensitivity method and the Monte Carlo method to evaluate the uncertainty in predictions for linear and nonlinear models. Four example applications are presented; a linear model, a model for the behavior of a damped spring-mass system, a transient thermal conduction model, and a nonlinear transient convective-diffusive model based on Burger's equation. Correlated and uncorrelated model input parameters are considered. The model validation tutorial builds on the material presented in the propagation of uncertainty tutoriaI and uses the damp spring-mass system as the example application. The validation tutorial illustrates several concepts associated with the application of statistical inference to test model predictions against experimental observations. Several validation methods are presented including error band based, multivariate, sum of squares of residuals, and optimization methods. After completion of the tutorial, a survey of statistical model validation literature is presented and recommendations for future work are made.

In this paper, we report details of our computational study of two shock wave physics experiments performed on the Sandia Z machine in 1998. The novelty of these particular experiments is that they represent the first successful appli- cation of VISAR interferometry to diagnose shock waves generated in experi- mental payloads by the primary X-ray pulse of the machine. We use the Sandia shock-wave physics code ALEGRA to perform the simulations reported in this study. Our simulations are found to be in fair agreement with the time-resolved VISAR experimental data. However, there are also interesting and important discrepancies. We speculate as to future use of time-resolved shock wave data to diagnose details of the Z machine X-ray pulse in the future.

Optical Micro Electro Mechanical Systems (Optical MEMS) Technology holds the promise of one-day producing highly integrated optical systems on a common, monolithic substrate. The choice of fabrication technology used to manufacture Optical MEMS will play a pivotal role in the size, functionality and ultimately the cost of optical Microsystems. By leveraging the technology base developed for silicon integrated circuits, large batches of routers, emitters, detectors and amplifiers will soon be fabricated for literally pennies per part. In this article we review the current status of technologies used for Optical MEMS, as well as fabrication technologies of the future, emphasizing manufacturable surface micromachining approaches to producing reliable, low-cost devices for optical communications applications.

The Sandia National Laboratories (SNL) Data Encryption Standard (DES) Application Specific Integrated Circuit (ASIC) is the fastest known implementation of the DES algorithm as defined in the Federal Information Processing Standards (FIPS) Publication 46-2. DES is used for protecting data by cryptographic means. The SNL DES ASIC, over 10 times faster than other currently available DES chips, is a high-speed, filly pipelined implementation offering encryption, decryption, unique key input, or algorithm bypassing on each clock cycle. Operating beyond 105 MHz on 64 bit words, this device is capable of data throughputs greater than 6.7 Billion bits per second (tester limited). Simulations predict proper operation up to 9.28 Billion bits per second. In low frequency, low data rate applications, the ASIC consumes less that one milliwatt of power. The device has features for passing control signals synchronized to throughput data. Three SNL DES ASICS may be easily cascaded to provide the much greater security of triple-key, triple-DES.

We have observed low threshold operation of a broadly tunable (2.18-3.4 µm) pump-resonant cw periodically poled lithium niobate (PPLN) optical parametric oscillator (OPO). When pumped at 806 nm with 410 mW from a custom-built diode laser the OPO generated 20 mW of idler output at 3.3 µm.

Anisotropic, smooth etching of the group-III nitrides has been reported at relatively high rates in high-density plasma etch systems. However, such etch results are often obtained under high de-bias andlor high plasma flux conditions where plasma induced damage can be significant. Despite the fact that the group-III nitrides have higher bonding energies than more conventional III-V compounds, plasma-induced etch damage is still a concern. Attempts to minimize such damage by reducing the ion energy or increasing the chemical activity in the plasma often result in a loss of etch rate or anisotropy which significantly limits critical dimensions and reduces the utility of the process for device applications requiring vertical etch profiles. It is therefore necessary to develop plasma etch processes which couple anisotropy for critical dimension and sidewall profile control and high etch rates with low-damage for optimum device performance. In this study we report changes in sheet resistance and contact resistance for n- and p-type GaN samples exposed to an Ar inductively coupled plasma (ICP). In general, plasma-induced damage was more sensitive to ion bombardment energies as compared to plasma flux. In addition, p-GaN was typically more sensitive to plasma-induced damage as compared to n-GaN.

We are developing a method for the real-time analysis of airborne microparticles based on laser ablation mass spectroscopy. Airborne particles enter an ion trap mass spectrometer through a differentially-pumped inlet, are detected by light scattered from two CW laser beams, and sampled by a 10 ns excimer laser pulse at 308 nm as they pass through the center of the ion trap electrodes. After the laser pulse, the stored ions are separated by conventional ion trap methods. In this work thousands of positive and negative ion spectra were collected for eighteen different species: six bacteria, six pollen, and six particulate samples. The data were then averaged and analyzed using the Multivariate Patch Algorithm (MPA), a variant of traditional multivariate anal ysis. The MPA correctly identified all of the positive ion spectra and 17 of the 18 negative ion spectra. In addition, when the average positive and negative spectra were combined the MPA correctly identified all 18 species. Finally, the MPA is also able to identify the components of computer synthesized mixtures of the samples studied

We study the low-temperature in-plane magnetoresistance of tunnel-coupled quasi-one-dimensional quantum wires. The wires are defined by two pairs of mutually aligned split gates on opposite sides of a < 1 micron thick AlGaAs/GaAs double quantum well heterostructure, allowing independent control of their widths. In the ballistic regime, when both wires are defined and the field is perpendicular to the current, a large resistance peak at ~6 Tesla is observed with a strong gate voltage dependence. The data is consistent with a counting model whereby the number of subbands crossing the Fermi level changes with field due to the formation of an anticrossing in each pair of 1D subbands.

On November 23, 1998, an 18,000-foot-deep wild-cat natural gas well being drilled near Bakersfield, CA blew out and caught fire. All attempts to kill this well failed, and the well continues to flow under limited control, producing large volumes of natural gas, salt water, and some oil. The oil and some of the water is being separated and trucked off site, and the remaining gas and water is being burned at the well head. A relief well is being drilled approximately one-quarter mile away in an attempt to intercept the first well. If the relief well is successful, it will be used to cement in and kill the first well. Epoch Wellsite Services, Inc., the mud-logging company for the initial well and the relief well, requested Sandia's rolling float meter (RFM) for these critical drilling operations. The RFM is being used to measure the mud outflow rate and detect kicks while drilling the relief well, which will undoubtedly encounter reservoir conditions similar to those responsible for the blow out. Based on its prior experience with the RFM, Epoch believes that it is the only instrument capable of providing the level of accuracy and response to mudflow needed to quickly detect kicks and minimize the risk of a blowout on this second critical well. In response to the urgent request from industry, Sandia and Epoch technicians installed the RFM on the relief well return line, and completed its initial calibration. The data from the RFM is displayed in real-time for the driller, the companyman, and the toolpusher via Epochs RIGWATCH Drilling Instmmentation System. The RFM has already detected several small kicks while drilling toward the annulus of the blown out well. A conventional paddle meter is located downstream of the RFM to provide redundancy and the opportunity to compare the two meters in an actual drilling operation, The relief well is nearing 14,000 feet deep, targeting an intercept of the first well near 17,600 feet. The relief well is expected to be completed in about 30 days. Several other Sandia instruments being developed for geothermal drilling are also being evaluated during this operation, Successful performance of these instruments on this important drilling job will reinforce our efforts to commercialize this technology for the geothermal and oil and gas drilling industries. Sandia's Rolling Float Meter was developed through the Lost Circulation Technology Program sponsored by the U. S. Department of Energy, Office of Geothermal Technologies. It monitors drilling fluid returns to rapidly detect loss of circulation during geothermal drilling. Lost circulation is particularly prevalent in geothermal wells, and can add as much as 10% to the total cost of drilling the well. Consequently, rapid detection and treatment of lost circulation is necessary for cost- effective geothermal drilling. Sandia has been evaluating and demonstrating the capabilities of the RFM to the geothermal industry for several years. In addition to lost circulation, the RFM is also useful for accurately detecting well kicks. Contacts have been made with mud logging companies that are involved with both geothermal and oil and gas drilling operations.

Microstructure in the reaction interface between molten Al and dense mullite have been studied by transmission electron microscopy to provide insight into mechanisms for forming ceramic-metal composites by reactive metal penetration. The reactions, which have the overall stoichiometry, 3Al#iz01~ + (8+ x)A1 + 13 AlzO~ + xA1 + 6Si, were carried out at temperatures of 900, 1100, and 1200oC for 5 minutes and 60 minutes, and 1400oC for 15 minutes. Observed phases generally were those given in the above reaction, although their proportions and interracial rnicrostructures differed strongly with reaction temperature. After reaction at 900oC, a thin Al layer separated unreacted mullite from the cx-AlzO~ and Al reaction products. No Si phase was found near the reaction front. After 5 minutes at 1100"C, the nxtction front contained Si, ct-A120~, and an aluminum oxide phase with a high concentration of Si. After 60 minutes at 11O(YC many of the cx-A120g particles were needle-shaped with a preferred orientation. After reaction at 1200oC, the reaction front contained a high density of Si particles that formed a continuous layer over many of the mullite grains. The sample reacted at 140VC for 15 minutes had a dense ct-A120J reaction layer less than 2~m thick. Some isolated Si particles were present between the a-AlzO~ layer and the unreacted mullite. Using previously measured reaction kinetics data, the observed temperature dependence of the interracial microstructure have been modeled as three sequential steps, each one of which is rate-limiting in a different temperature range.

Arbitrary Lagrangian Eulerian (ALE) computational techniques allow treatment of gases, liq- uids, and solids in the same simulation. ALE methods include the ability to treat shockwaves in gases, liquids, and solids and the interaction of shockwaves with each other and with media from one of the other categories. ALE codes can also treat explosive detonation and the expansion of the explosive gases and their interaction with air and solids. ALEGRA is a 3-DALE code that has been developed at Sandia National Laboratories over the past few years. ALEGRA has been applied to a 2-D simulation of presplitting using decoupled explosives in rock blasting with very interesting results. The detonation of the explosive at the bottom of the hole sends a shock wave up the borehole driven by the explosive gas expanding into air. The explosive gas compresses the air against the stemming column where it rebounds and recompresses at the bottom of the borehole. This type of ringing takes several cycles to damp out. The explosively induced expansion of the borehole is also treated by ALEGRA as well as the shock wave imparted to the rock. The presentation of this paper will include sev- eral computer animations to aid in understanding this complex phenomenon.

This criticality safety analysis is performed to determine the effective multiplication factor (k_eff) for a storage cabinet filled with unirradiated Cintichem-type targets. These targets will be used to produce ⁹⁹Mo at Sandia National Laboratories and will be stored on-site prior to irradiation in the Annular Core Research Reactor. The analysis consisted of using the Monte Carlo code MCNP (Version 4A) to model and predict the k_eff for the proposed dry storage configuration under credible loss of geometry and moderator control. Effects of target pitch, non-uniform loading, and target internal/external flooding are evaluated. Further studies were done with deterministic methods to verify the results obtained from MCNP and to obtain a clearer understanding of the parameters affecting system criticality. The diffusion accelerated neutral particle transport code ONEDANT was used to model the target in a one-dimensional, infinite half-slab geometry and determine the critical slab thickness. Hand calculations were also completed to determine the critical slab thickness with modified one-group, and one-group, two region approximations. Results obtained from ONEDANT and the hand calculations were compared to applicable cases in a commonly used criticality safety analysis handbook. Overall, the critical slab thicknesses obtained in the deterministic analysis were much larger than the dimensions of the cabinet and further support the predictions by MCNP that a critical system cannot be attained for the base case or in conditions where loss of geometry and moderation control occur.

Localization of light to less than a cubic wavelength, {lambda}{sup 3}, has important quantum consequences. The creation of single mode cavities and the modification of spontaneous emission are two important examples. A defect formed inside a three-dimensional (3D) photonic crystal provides an unique optical environment for light localization. Single mode defect cavities were built, for the first time, from an infrared 3D photonic crystal. A cavity state with modal volume of less than one {lambda}{sup 3} was observed.

Two main assumptions which underlie the Stoney formula relating substrate curvature to mis-match strain in a bonded thin film are that the film is very thin compared to the substrate, and the deformations are infinitesimally small. Expressions for the curvature-strain relastionship are derived for cases in which thses assumptions are relaxed, thereby providing a biasis for interpretation of experimental observations for a broader class of film-substrate configurations.

The formation of quantum wires has much interest due to their novel electronic properties which may lead to enhanced optoelectronic device performance and greater photovoltaic efficiencies. One method of forming these structures is through spontaneous lateral modulation found during the epitaxial growth of III/V alloys. In this paper, we report and summarize our investigations on the formation of lateral moduation in the MBE grown InAlAs/InP(001) system. This system was grown as a short-period superlattice where n-monolayers of InAs are deposited followed by m-Monolayers of AlAs (with n and m~2) and this sequence is repeated to grown a low strain InAlAs ternary alloy on InP(001) that exhibits lateral modulation. Films were grown under a variety of condition (growth temperature, effective alloy composition, superlattice period, and growth rate). These films have been extensively analyzed using X-ray diffraction, atomic force microscopy, and transmission electron microscopy (TEM) and microcharacterization, in addition to photon-based spectroscopes. Here we present results of several microstructural characterizations using a wide range of TEM-based techniques, and compare them to results from the other methods to obtain a unified understanding of composition modulation. Two strong points consistently emerge: 1) The lateral modulation wavelength is insensitive to growth temperature and effective alloy composition, but the strength of the lateral modulation is greatest near an effective alloy composition of In(0.46)Al(0.54)As, which corresponds to a slightly tensile global strain with respect to InP. 2) The composition variation for the strongly modulated films is as much as 0.38 InAs mole fraction. In addition, for these strongly modulated films, the modulation wave is asymmetric showing strongly peaked, narrower InAs-rich regions separated by flat AlAs-rich regions. We discuss these results and their possible implications in addition to detailing the techniques used to obtain them.

Pattern formation on surfaces undergoing low-energy ion bombardment is a common phenomenon. Here, a recently developed in situ spectroscopic light scattering technique was used to monitor periodic ripple evolution on Si(001) during Ar(+) sputtering. Analysis of the rippling kinetics indicated that under high flux sputtering at low temperatures the concentration of mobile species on the surface is saturated, and, surprisingly, is both temperature and ion flux independent. This is due to an effect of ion collision cascades on the concentration of mobile species. This new understanding of surface dynamics during sputtering allowed us to measure straighforwardly the activation energy for atomic migration on the surface to be 1.2+0.1 eV. The technique is generalizable to any material, including high temperature and insulating materials for which surface migration energies are notoriously difficult to measure.

The suitability of the wavelength range provided by silicon photodiode detector arrays for monitoring the spectral reflectance during epitaxial growth of GaSb, AlGaAsSb, and GaInAsSb, which have cutoff wavelengths at 25 degree C of 1.7, 1.2, and 2.3 um, respectively, is demonstrated. These alloys were grown lattice matched to GaSb in a vertical rotating-disk reactor, which was modified to accommodate near normal reflectance without affecting epilayer uniformity, By using a virtual interface model, the growth rate and complex refractive index at the growth temperature are extracted for these alloys over the 600 to 1000 nm spectral range. Excellent agreement is obtained between the extracted growth rate and that determined by ex-situ measurement.

The porosities of three mesoporous silica materials were characterized with {sup 129}Xe NMR spectroscopy. The materials were synthesized by a sol-gel process with r = 0, 25, and 70% methanol by weight in an aqueous cetyltrimethylammonium bromide solution. Temperature dependent chemical shifts and spin lattice relaxation times reveal that xenon does not penetrate the pores of the largely disordered (r= 70%) silica. For both r = 0 and 25%, temperature dependent resonances corresponding to physisorbed xenon were observed. An additional resonance for the r = 25% sample was attributed to xenon between the disordered cylindrical pores. 2D NMR exchange experiments corroborate the spin lattice relaxation data which show that xenon is in rapid exchange between the adsorbed and the gas phase.

The authors present a compact, robust, solid-state blue light (490 nm) source capable of greater than 5 mW of output in a TEM{sub 00} mode. This device is an optically pumped, vertical external-cavity surface-emitting laser (VECSEL) with an intracavity frequency doubling crystal.

Deposition parameters were found to have a marked effect on piezoelectric response of reactive radio frequency (RF) sputtered AlN thin films. The authors observed peizoelectric response values ranging from {minus}3.5 to +4.2 pm/V for 1 {micro}m thick AlN films deposited onto Ti/Ru electrode stacks. An investigation of the effects of deposition parameters, in particular the nature of the Ru/AlN interface, was conducted. The lag time between deposition of adjacent thin film layers appeared to have the greatest affect on the value of the piezoelectric response. This suggests that chemical reaction occurring on the Ru thin film surface is responsible for changing an important thin film property such as dipole orientation within the overlying AlN thin film.

In this paper, we introduce a new approach for altering the properties of bridged polysilsesquioxane xerogels using post-processing modification of the polymeric network. The bridging organic group contains latent functionalities that can be liberated thermally, photochemically, or by chemical means after the gel has been processed to a xerogel. These modifications can produce changes in density, volubility, porosity, and or chemical properties of the material. Since every monomer possesses two latent functional groups, the technique allows for the introduction of high levels of functionality in hybrid organic-inorganic materials. Dialkylenecarbonate-bridged polysilsesquioxane gels were prepared by the sol-gel polymerization of bis(triethoxysilylpropyl)carbonate (1) and bis(triethoxysilylisobutyl)-carbonate (2). Thermal treatment of the resulting non-porous xerogels and aerogels at 300-350 C resulted in quantitative decarboxylation of the dialkylenecarbonate bridging groups to give new hydroxyalkyl and olefinic substituted polysilsesquioxane monolithic xerogels and aerogels that can not be directly prepared through direct sol-gel polymerization of organotrialkoxysilanes.

JavaScript allows the definition and use of large, complex objects. Unlike some other object-oriented languages, it also allows run-time modifications not only of the values of object components, but also of the very structure of the object itself. This feature is powerful and sometimes very convenient, but it can be difficult to keep track of the object's structure and values throughout program execution. What's needed is a simple way to view the current state of an object at any point during execution. There is a debug function that is included in the Netscape server-side JavaScript environment. The function outputs the value(s) of the expression given as the argument to the function in the JavaScript Application Manager's debug window [SSJS].

Traditional safety and reliability analysis methods are applicable to many standard problems, including those examples illustrated in most formal courses. However, there are many real-world situations for which non-traditional methods appear to be more appropriate, mainly because most practical problems involve substantial subjectivity about the inputs and models used. This paper surveys some of the most applicable approaches found in a recent research study. Each approach is developed individually and is illuminated by selecting example situations of apparent applicability. Then, the combinational blending of the approaches with each other and with traditional methodology is discussed.

Work of adhesion (Wa) measurements are being studied for several types of polymer/metal combinations in order to obtain a better understanding of the adhesive failure mechanisms for systems containing encapsulated and bonded components. A primary concern is whether studies of model systems can be extended to systems of technological interest. One study performed in our laboratory involved the determination of Wa between silicone (PDMS) and Al surfaces in order to establish potential adhesive failure mechanisms. Our initial work with PDMS was based on Dow Corning 170 Sylgard. PDMS hemispheres were synthesized following the procedure outlined by Chaudhury and Whitesides where the filler was stripped from the commercial silicone by centrifuging. Wa between PDMS surfaces was determined using the JKR method. Our results for the Wa of PDMS were in agreement with those reported by Chaudhury and Whitesides. However, further JKR studies using these PDMS hemispheres on flat Al surfaces were fraught with difficulty. We could not discriminate hydrogen-bonding effects between Al{sub 2}O{sub 3} and hydroxyl groups in the PDMS and other possible bonding mechanisms. It was suggested that commercial systems contain inhibitors and additives that interfere with understanding the PMDS/Al interface. Therefore, the current study uses pure PDMS networks synthesized in our lab. Also, two contact mechanics methods were deployed to measure the Wa--JKR method using two hemispheres and a LEFM method using a cylinder containing a circumferential crack. This paper contains a description of the synthesis of the PDMS used for these studies and the determination of Wa between PDMS surfaces using the JKR method, contact angle measurements, and a LEFM method that consists of a cylinder containing a circumferential crack.

This editorial paper presents a vision for intelligent health care in the home of the future, focusing on technologies with the highest potential payoff given targeted government funding over the next ten years. A secure, plug-and-play information framework provides the starting point for identifying technologies that must be developed before home-based devices can know their context and assimilate information to support care decisions.

We propose an object-oriented information architecture for telemedicine systems that promotes secure `plug-and-play' interaction between system components through standardized interfaces, communication protocols, messaging formats, and data definitions. In this architecture, each component functions as a black box, and components plug together in a ''lego-like'' fashion to achieve the desired device or system functionality. Introduction Telemedicine systems today rely increasingly on distributed, collaborative information technology during the care delivery process. While these leading-edge systems are bellwethers for highly advanced telemedicine, most are custom-designed and do not interoperate with other commercial offerings. Users are limited to a set of functionality that a single vendor provides and must often pay high prices to obtain this functionality, since vendors in this marketplace must deliver en- tire systems in order to compete. Besides increasing corporate research and development costs, this inhibits the ability of the user to make intelligent purchasing decisions regarding best-of-breed technologies. This paper proposes a reference architecture for plug-and-play telemedicine systems that addresses these issues.

Global Nuclear Materials Management (GNMM) anticipates and supports a growing international recognition of the importance of uniform, effective management of civilian, excess defense, and nuclear weapons materials. We expect thereto be a continuing increase in both the number of international agreements and conventions on safety, security, and transparency of nuclear materials, and the number of U.S.-Russian agreements for the safety, protection, and transparency of weapons and excess defense materials. This inventory of agreements and conventions may soon expand into broad, mandatory, international programs that will include provisions for inspection, verification, and transparency, To meet such demand the community must build on the resources we have, including State agencies, the IAEA and regional organizations. By these measures we will meet the future expectations for monitoring and inspection of materials, maintenance of safety and security, and implementation of transparency measures.

Sandia has implemented a formal process to verify that new or modified facilities and operations are ready to safely operate. The readiness review process focuses on the status of management systems, personnel, and systems, structures, and components to do work safely. The scope and depth of the review are tailored to match the potential consequences and the likelihood that the consequences could occur. The precepts and methodology of the process are applicable to verifying the readiness of enterprise systems, and should comprise the final element in developing and implementing an enterprise system. This paper describes the readiness review process, the key elements for success, lessons learned from Sandia's readiness assessment process, and outlines how the process can be applied to enterprise systems. Specific topics addressed include selecting the criteria, approach, and lines of inquiry to be used for the review; selecting members for the review team; team leader responsibilities; reporting and closing deficiencies; and, responsibilities of the facility/project owner and management.

Irradiation of red meat and poultry has been approved by the U.S. FDA, and the U.S. Department of Agriculture's rule for processing red meat is out for comment. Looking beyond the current issues of packaging materials, labeling, and consumer acceptance, this paper reviews the next step of implementation and how to remove, or at least reduce, the barriers to utilization. Polls of the user community identified their requirements for electron beam or x-ray processing of meat or poultry and their concerns about implementation for on-line processing. These needs and issues are compared to the capabilities of the accelerator industry. The critical issues of beam utilization and dose uniformity, factors affecting floor space requirements, and treatment costs are examined.

Boolean logic expressions are often derived in safety and reliability analysis. Since the values of the operands are rarely exact, accounting for uncertainty with the tightest justifiable bounds is important. Accurate determination of result bounds is difficult when the inputs have constraints. One example of a constraint is that an uncertain variable that appears multiple times in a Boolean expression must always have the same value, although the value cannot be exactly specified. A solution for this repeated variable problem is demonstrated for two Boolean classes. The classes, termed functions with unate variables (including, but not limited to unate functions), and exclusive-or functions, frequently appear in Boolean equations for uncertain outcomes portrayed by logic trees (event trees and fault trees).

This paper presents results from a series of preliminary tests to evaluate a scannerless range-imaging device as a potential sensory enhancement tool for divers and as a potential identification sensor for deployment on small unmanned underwater vehicles. The device, developed by Sandia National Laboratories, forms an image on the basis of point-to-point range to the target rather than an intensity map. The range image is constructed through a classical continuous wave phase detection technique in which the light source is amplitude modulated at radio frequencies. The receiver incorporates a gain-modulated image intensifier, and range information is calculated on the basis of the phase difference between the transmitted and reflected signal. The initial feasibility test at the Coastal Systems Station showed the device to be effective at imaging low-contrast underwater targets such as concertina wire. It also demonstrated success at imaging a 21-inch sphere at a depth of 10 feet in the water column through a wavy air-water interface.

In 1991, the Federal Aviation Administration (FAA) established an Airworthiness Assurance NDI Validation Center (AANC) at Sandia National Laboratories. Its primary mission is to support technology development, validation, and transfer to industry in order to enhance the airworthiness and improve the aircraft maintenance practices of the U.S. commercial aviation industry. The Center conducts projects in a myriad of engineering disciplines. The results are placed in the public domain so that the industry at-large can reap the benefits of FAA-funded Research and Development efforts. To support the Center's goals, the FAA/AANC has set up a hangar facility at the Albuquerque International Airport which contains a collection of transport and commuter aircraft as well as other test specimens. The facility replicates a working maintenance environment by incorporating both the physical inspection difficulties as well as the environmental factors which influence maintenance reliability.

Over a period of 15 months, five sets of adhesively-bonded butt joints were fabricated and tested. This previously unreported data is used to assess the variability of measured interface corner toughness values, K{sub ac}, as well as the dependence of K{sub ac} on surface preparation. A correlation between K{sub ac} and the size of the adhesive failure zone is also noted.

The authors consider a chain of elastic (Hertzian) grains that repel upon contact according to the potential V = a{delta}{sup u}, u > 2, where {delta} is the overlap between the grains. They present numerical and analytical results to show that an impulse initiated at an end of a chain of Hertzian grains in contact eventually propagates as a soliton for all n > 2 and that no solitons are possible for n {le} 2. Unlike continuous, they find that colliding solitons in discrete media initiative multiple weak solitons at the point of crossing.

Abstract not provided.

This paper outlines general physical and computational issues associated with performing numerical simulation of fire suppression. Fire suppression encompasses a broad range of chemistry and physics over a large range of time and length scales. The authors discuss the dominant physical/chemical processes important to fire suppression that must be captured by a fire suppression model to be of engineering usefulness. First-principles solutions are not possible due to computational limitations, even with the new generation of tera-flop computers. A basic strategy combining computational fluid dynamics (CFD) simulation techniques with sub-grid model approximations for processes that have length scales unresolvable by gridding is presented.

As we enter the new millennium, let us recognize that the losses resulting from natural or malevolent events that cause major property damage, severe injuries, and unnecessary death are not always due to forces beyond our control. We can prevent these losses by changing the way we think and act about design and construction projects. New tools, technologies, and techniques can improve structural safety, security, and reliability and protect owners, occupants, and users against loss and casualties. Hurricane Mitch, the African embassy bombings, the ice storms in Canada and the northeastern US last winter, the Oklahoma City bombing, flooding and earthquakes in California, tornadoes and flooding in Florida, and wildfires in the Southwest are threats to the safety and security of the public and the reliability of our constructed environment. Today's engineering design community must recognize these threats and address them in our standards, building codes, and designs. We know that disasters will continue to strike and we must reduce their impact on the public. We must demand and create innovative solutions that assure a higher level of structural performance when disasters strike.

Z-pinches created using the Z accelerator generate {approximately}220 TW, 1.7 MJ radiation pulses that heat large ({approximately}10 cm{sup 3}) hohlraums to 100-150 eV temperatures for times of order 10 nsec. We are performing experiments exploiting this intense radiation to drive shock waves for equation of state studies. The shock pressures are typically 1-10 Mbar with 10 nsec duration in 6-mm-diameter samples. In this paper we demonstrate the ability to perform optical spectroscopy measurements on shocked samples located in close proximity to the z-pinch. These experiments are particularly well suited to optical spectroscopy measurements because of the relatively large sample size and long duration. The optical emission is collected using fiber optics and recorded with a streaked spectrograph. Other diagnostics include VISAR and active shock breakout measurements of the shocked sample and a suite of diagnostics that characterize the radiation drive. Our near term goal is to use the spectral emission to obtain the temperature of the shocked material. Longer term objectives include the examination of deviations of the spectrum from blackbody, line emission from lower density regions, determination of kinetic processes in molecular systems, evaluation of phase transitions such as the onset of metalization in transparent materials, and characterization of the plasma formed when the shock exits the rear surface. An initial set of data illustrating both the potential and the challenge of these measurements is described.

Sandia Laboratories' computational scientists are addressing a very important question: How do we get insight from the human combined with the computer-generated information? The answer inevitably leads to using scientific visualization. Going one technology leap further is teraflop visualization, where the computing model and interactive graphics are an integral whole to provide computing for insight. In order to implement our teraflop visualization architecture, all hardware installed or software coded will be based on open modules and dynamic extensibility principles. We will illustrate these concepts with examples in our three main research areas: (1) authoring content (the computer), (2) enhancing precision and resolution (the human), and (3) adding behaviors (the physics).

Over the past two years, New Mexico has been engaged in a significant new approach to implement large purchases of solar power. This effort followed a regulatory process that treated solar power generation similar to conventional generation obtained by an investor-owned utility under the regulation of a public utility commission. In 1997, Public Service Company of New Mexico (PNM) gained approval to purchase power from a 100-MW combustion turbine facility that would be owned and operated by a wholesale generator. At the same time it issued the approval, and following discussions with the utility, the New Mexico Public Utility Commission (NMPUC) also required PNM to issue a request for proposal for a 5-MW central station solar facility, a major step for solar technologies in the state, in what would be the world's largest of its technology type. In cooperation with the staff of the NMPUC, PNM reviewed the proposals received, and Applied Power Corporation was selected for the photovoltaic portion of the proposed plan; retaining ownership of the plant, assuming the risks connected with the technology, and operating the plant in exchange for a power purchase agreement in a first-of-its-kind contract for photovoltaics. During the NMPUC hearings, various parties raised significant opposition to the cost-recovery mechanism that was proposed and voiced issues about the type of solar plant, its size, cost and the tiding approaches to building it. Because of these issues, alternative proposals were put forth that reduced the size and costs of the plant and had implied changes in ownership and risks. The order issued by the NMPUC on October 21, 1998, requires PNM to impose a charge of 0.5% on its retail electric customers' monthly bills to be used to acquire the solar facilities, but also to obtain other renewable electric power resources, both on a pay-as-you-go basis. This paper identifies the issues and their resolution that similar projects are expected to encounter.

We conducted three sets of depth-of-penetration experiments with limestone targets and 3.0 caliber-radius-head (CRH), ogive-nose steel rod projectiles. The limestone targets had a nominal unconfined compressive strength of 60 MPa, a density of 2.31 kg/m{sup 3}, a porosity of 15%, and a water content less than 0.4%. The ogive-nose rod projectiles with length-to-diameter ratios often were machined from 4340 R{sub c} 45 and Aer Met 100 R{sub c} 53 steel, round stock and had diameters and masses of 7.1 mm, 0.020 kg; 12.7 mm, 0.117 kg; and 25.4 mm, 0.931 kg. Powder guns or a two-stage, light-gas gun launched the projectiles at normal impacts to striking velocities between 0.4 and 1.9 km/s. For the 4340 R{sub c} 45 and Aer Met 100 R{sub c} 53 steel projectiles, penetration depth increased as striking velocity increased to a striking velocity of 1.5 and 1.7 km/s, respectively. For larger striking velocities, the projectiles deformed during penetration without nose erosion, deviated from the shot line, and exited the sides of the target. We also developed an analytical penetration equation that described the target resistance by its density and a strength parameter determined from depth of penetration versus striking velocity data.

The delivery of the first one tera-operations/sec computer has significantly impacted production data visualization, affecting data transfer, post processing, and rendering. Terascale computing has motivated a need to consider the entire data visualization system; improving a single algorithm is not sufficient. This paper presents a systems approach to decrease by a factor of four the time required to prepare large data sets for visualization.For daily production use, all stages in the processing pipeline from physics simulation code to pixels on a screen, must be balanced to yield good overall performance. Also, to complete the data path from screen to the analyst's eye, user display systems for individuals and teams are examined. Performance of the initial visualization system is compared with recent improvements. Lessons learned from the coordinated deployment of improved algorithms are also discussed, including the need for 64 bit addressing and a fully parallel data visualization pipeline.

An evaluation of biotic and abiotic attenuation processes potentially important to chlorinated and non-chlorinated volatile organic compound (VOC) fate and transport in the 148 meter thick vadose zone beneath the Chemical Waste Landfill (CWL) was conducted. A unique feature of this evaluation is the comparison of two estimates of VOC mass present in the soil gas, pore-water, and solid phases (but not including mass as non-aqueous phase liquid [NAPL]) of the vadose zone in 1993. One estimate, 1,800 kg, was obtained from vadose zone transport modeling that incorporated molecular diffusion and volatilization to the atmosphere, but not biotic or chemical processes. The other estimate, 2,120 kg, was obtained from the sum of VOC mass physically removed during soil vapor extraction and an estimate of VOC mass remaining in the vadose zone in 1998, both adjusted to exclude NAPL mass. This comparison indicates that biogeochemical processes were at best slightly important to historical VOC plume development. Some evidence of aerobic degradation of non-chlorinated VOCs and abiotic transformation of 1,1,1-Trichloroethane was identified. Despite potentially amenable site conditions, no evidence was found of cometabolic and anaerobic transformation pathways. Relying principally on soil-gas analytical results, an upper-bound estimate of 21% mass reduction due to natural biogeochemical processes was developed. Although available information for the CWL indicates that natural attenuation processes other than volatilization to the atmosphere did not effective y enhance groundwater protection, these processes could be important in significantly reducing groundwater contamination and exposure risks at other sites. More laboratory and field research is required to improve our collective ability to characterize and exploit natural VOC attenuation processes, especially with respect to the combination of relatively thick and dry vadose zones and chlorinated VOCs.

Abstract not provided.

Telemedicine technology is rapidly evolving. Whereas early telemedicine consultations relied primarily on video conferencing, consultations today may utilize video conferencing, medical peripherals, store-and-forward capabilities, electronic patient record management software, and/or a host of other emerging technologies. These remote care systems rely increasingly on distributed, collaborative information technology during the care delivery process, in its many forms. While these leading-edge systems are bellwethers for highly advanced telemedicine, the remote care market today is still immature. Most telemedicine systems are custom-designed and do not interoperate with other commercial offerings. Users are limited to a set of functionality that a single vendor provides and must often pay high prices to obtain this functionality, since vendors in this marketplace must deliver entire systems in order to compete. Besides increasing corporate research and development costs, this inhibits the ability of the user to make intelligent purchasing decisions regarding best-of-breed technologies. We propose a secure, object-oriented information architecture for telemedicine systems that promotes plug-and-play interaction between system components through standardized interfaces, communication protocols, messaging formats, and data definitions. In this architecture, each component functions as a black box, and components plug together in a lego-like fashion to achieve the desired device or system functionality. The architecture will support various ongoing standards work in the medical device arena.

The US health care industry is experiencing a substantial paradigm shift with regard to home care due to the convergence of several technology areas. Increasingly-capable telehealth systems and the internet are not only moving the point of care closer to the patient, but the patient can now assume a more active role in his or her own care. These technologies, coupled with (1) the migration of the health care industry to electronic patient records and (2) the emergence of a growing number of enabling health care technologies (e.g., novel biosensors, wearable devices, and intelligent software agents), demonstrate unprecedented potential for delivering highly automated, intelligent health care in the home. This editorial paper presents a vision for the implementation of intelligent health care technology in the home of the future, focusing on areas of research that have the highest potential payoff given targeted government funding over the next ten years. Here, intelligent health care technology means smart devices and systems that are aware of their context and can therefore assimilate information to support care decisions. A systems perspective is used to describe a framework under which devices can interact with one another in a plug-and-play manner. Within this infrastructure, traditionally passive sensors and devices will have read/write access to appropriate portions of an individual's electronic medical record. Through intelligent software agents, plug-and-play mechanisms, messaging standards, and user authentication tools, these smart home-based medical devices will be aware of their own capabilities, their relationship to the other devices in the home system, and the identity of the individual(s) from whom they acquire data. Information surety technology will be essential to maintain the confidentiality of patient-identifiable medical information and to protect the integrity of geographically dispersed electronic medical records with which each home-based system will interact.

A model is developed herein for predicting the mechanical response of inelastic crystalline solids. Particular emphasis is given to the development of microstructural damage along grain boundaries, and the interaction of this damage with intragranular inelasticity caused by dislocation dissipation mechanisms. The model is developed within the concepts of continuum mechanics, with special emphasis on the development of internal boundaries in the continuum by utilizing a cohesive zone model based on fracture mechanics. In addition, the crystalline grains are assumed to be characterized by nonlinear viscoplastic mechanical material behavior in order to account for dislocation generation and migration. Due to the nonlinearities introduced by the crack growth and viscoplastic constitution, a numerical algorithm is utilized to solve representative problems. Implementation of the model to a finite element computational algorithm is therefore briefly described. Finally, sample calculations are presented for a polycrystalline titanium alloy with particular focus on effects of scale on the predicted response.

Application of Executive Order 12898 to risk assessment of highway or rail transport of hazardous materials has proven difficult; the location and conditions affecting the propagation of a plume of hazardous material released in a potential accident are unknown, in general. Therefore, analyses have only been possible in geographically broad or approximate manner. The advent of geographic information systems and development of software enhancements at Sandia National Laboratories have made kilometer-by-kilometer analysis of populations tallied by U.S. Census Blocks along entire routes practicable. Tabulations of total, or racially/ethnically distinct, populations close to a route, its alternatives, or the broader surrounding area, can then be compared and differences evaluated statistically. This paper presents methods of comparing populations and their racial/ethnic compositions using simple tabulations, histograms and Chi Squared tests for statistical significance of differences found. Two examples of these methods are presented: comparison of two routes and comparison of a route with its surroundings.

Epitaxial thin films of the Tl cuprate superconductors Tl{sub 2}Ba{sub 2}CaCu{sub 2}O{sub 8}, Tl{sub 2}Ba{sub 2}Ca{sub 2}Cu{sub 3}O{sub 10}, and TL{sub 0.78}Bi{sub 0.22}Ba{sub 0.4}Sr{sub 1.6}Ca{sub 2}Cu{sub 3}O{sub 9{minus}{delta}} are studied with x-ray photoemission spectroscopy. These data, together with previous measurements in this lab of Tl{sub 2}Ba{sub 2}CuO{sub 6+{delta}} and TlBa{sub 2}CaCu{sub 2}O{sub 7{minus}{delta}}, comprise a comprehensive data set for a comparative study of Tl cuprates with a range of chemical and electronic properties. In the Cu 2p spectra, a larger energy separation between the satellite and main peaks (E{sub s}-E{sub m}) and a lower intensity ratio (I{sub s}/I{sub m}) are found to correlate with higher values of T{sub c}. Analysis of these spectra within a simple configuration interaction model suggests that higher values of T{sub c} are related to low values of the O 2p {r_arrow} Cu 3d charge transfer energy. In the O 1s region, a smaller bond length between Ba and Cu-O planar oxygen is found to correlate with a lower binding energy for the signal associated with Cu-O bonding, most likely resulting from the increased polarization screening by Ba{sup 2+} ions. For samples near optimum doping, maximum T{sub c} is observed to occur when the Tl 4f{sub 7/2} binding energy is near 117.9 eV, which is near the middle of the range of values observed for Tl cuprates. Higher Tl 4f{sub 7/2} binding energies, corresponding to formal oxidation states nearer Tl{sup 1+}, are also found to correlate with longer bond lengths between Ba and Tl-O planar oxygen, and with higher binding energies of the O 1s signal associated with Tl-O bonding.

First-principles total energies of periodic vicinals are used to estimate barriers for Pt-adatom diffusion along straight and kinked steps on Pt(111), and around a corner where straight steps intersect. In all cases studied, hopping diffusion has a lower barrier than concerted substitution. In conflict with simulations of dendritic Pt island formation on Pt(111), hopping from a corner site to a step whose riser is a (111)-micro facet is predicted to be more facile than to one whose riser is a (100).

Scenario development has two primary purposes in the design and documentation of post-closure performance assessments in a regulatory setting. First, scenario development ensures a sufficiently comprehensive consideration of the possible future states of the system. Second, scenario development identifies the important scenarios that must be considered in quantitative analyses of the total system performance assessment (TSPA). Section 2.0 of this report describes the scenario development process. Steps in the process are described in Section 2.1, and terms introduced in this section are defined in Section 2.2. The electronic database used to document the process is described in Section 3, and Section 4 provides a summary of the current status of the YMP scenario development work. Section 5 contains acknowledgments, and Section 6 contains a list of the references cited.

We have discussed two aspects of creating high integrity software that greatly benefit from the availability of transformation technology, which in this case is manifest by the requirement for a sophisticated backtracking parser. First, because of the potential for correctly manipulating programs via small changes, an automated non-procedural transformation system can be a valuable tool for constructing high assurance software. Second, modeling the processing of translating data into information as a, perhaps, context-dependent grammar leads to an efficient, compact implementation. From a practical perspective, the transformation process should begin in the domain language in which a problem is initially expressed. Thus in order for a transformation system to be practical it must be flexible with respect to domain-specific languages. We have argued that transformation applied to specification results in a highly reliable system. We also attempted to briefly demonstrate that transformation technology applied to the runtime environment will result in a safe and secure system. We thus believe that the sophisticated multi-lookahead backtracking parsing technology is central to the task of being in a position to demonstrate the existence of HIS.

We have designed a new class of cyclic siloxane compounds that behave as sol-gel systems when ring open polymerized using a hydroxide base. These monomers polymerize through chain growth polymerization. unlike conventional alkoxysilane sol-gel precursors, to form sol-gel polymers. They do not require solvent or water for polymerization, show no visible shrinkage or cracking during polymerization and are thermally stable. We have successfully utilized these materials in encapsulation of microelectronics. Current efforts are focused toward expanding this family of ROP monomers and optimization of their mechanical properties.

Mission critical applications of MEMS devices require knowledge of the distribution in their material properties and long-term reliability of the small-scale structures. This project reports on a new testing program at Sandia to quantify the strength distribution using samples that reflect the dimensions of critical MEMS components. The strength of polysilicon fabricated with Sandia's SUMMiT 4-layer process was successfully measured using samples with gage sections 2.5 {micro}m thick by 1.7 {micro}m wide and lengths of 15 and 25 {micro}m. These tensile specimens have a freely moving pivot on one end that anchors the sample to the silicon die and prevents off axis loading during testing. Each sample is loaded in uniaxial tension by pulling laterally with a flat tipped diamond in a computer-controlled Nanoindenter. The stress-strain curve is calculated using the specimen cross section and gage length dimensions verified by measuring against a standard in the SEM. The first 48 samples had a means strength of 2.24 {+-} 0.35 GPa. Fracture strength measurements grouped into three strength levels, which matched three failure modes observed in post mortem examinations. The seven samples in the highest strength group failed in the gage section (strength of 2.77 {+-} 0.04 GPa), the moderate strength group failed at the gage section fillet and the lowest strength group failed at a dimple in the hub. With this technique, multiple tests can be programmed at one time and performed without operator assistance at a rate of 20-30 per day allowing the collection of significant populations of data. Since the new test geometry has been proven, the project is moving to test the distributions seen from real geometric features typical to MEMS such as the effect of gage length, fracture toughness, bonding between layers, etch holes, dimples and shear of gear teeth.

The paper provides a concise overview of a coordinated experimental/theoretical/numerical program at Sandia National Laboratories to develop an experimentally validated model of fire-induced response of foam-filled engineered systems for nuclear and transportation safety applications. Integral experiments are performed to investigate the thermal response of polyurethane foam-filled systems exposed to fire-like heat fluxes. A suite of laboratory experiments is performed to characterize the decomposition chemistry of polyurethane. Mass loss and energy associated with foam decomposition and chemical structures of the virgin and decomposed foam are determined. Decomposition chemistry is modeled as the degradation of macromolecular structures by bond breaking followed by vaporization of small fragments of the macromolecule with high vapor pressures. The chemical decomposition model is validated against the laboratory data. Data from integral experiments is used to assess and validate a FEM foam thermal response model with the chemistry model developed from the decomposition experiments. Good agreement was achieved both in the progression of the decomposition front and the in-depth thermal response.

Abstract not provided.

Abstract not provided.

The primary purpose of this LDRD project was to characterize the laser deposition process and determine the feasibility of fabricating complex near-net shapes directly from a CAD solid model. Process characterization provided direction in developing a system to fabricate complex shapes directly from a CAD solid model. Our goal for this LDRD was to develop a system that is robust and provides a significant advancement to existing technologies (e.g., polymeric-based rapid prototyping, laser welding). Development of the process will allow design engineers to produce functional models of their designs directly from CAD files. The turnaround time for complex geometrical shaped parts will be hours instead of days and days instead of months. With reduced turnaround time, more time can be spent on the product-design phase to ensure that the best component design is achieved. Maturation of this technology will revolutionize the way the world produces structural components.

Hot Isostatic Pressing (HIP) is investigated as a technique for joining the cermet WC-15% Co to itself. Encapsulation of the specimens prior to HIPing was carried out using steel encapsulation, glass encapsulation and self encapsulation. The bonds were evaluated using a four point bend method. It is shown that the glass and steel encapsulation methods have a number of inherent problems which make them inappropriate for near net shape processing. In contrast the novel self encapsulation method, described for the first time in this communication, is both simple and effective, producing joined material with bulk strength. The concept of self encapsulation is potentially widely applicable for joining composite materials.

We report on the application of the one-level FETI method to the solution of a class of structural problems associated with the Department of Energy's Accelerated Strategic Computing Initiative (ASCI). We focus on numerical and parallel scalability issues,and discuss the treatment by FETI of severe structural heterogeneities. We also report on preliminary performance results obtained on the ASCI Option Red supercomputer configured with as many as one thousand processors, for problems with as many as 5 million degrees of freedom.

Polyorganosiloxanes are a commercially important class of compounds. They exhibit many important properties, including very low glass transition temperatures, making them useful over a wide temperature range. In practice, the polysiloxane polymer is often mixed with a filler material to help improve its mechanical properties. An alternative method for increasing polymer mechanical strength is through the incorporation of certain substituents on the polymer backbone. Hard substituents such as carbonates and imides generally result in improved mechanical properties of polysiloxanes. In this paper, we present the preparation of novel polysiloxane resins modified with hard maleimide substituents. Protected ethoxysilyl-substituted propyl-maleimides were prepared. The maleimide substituent was protected with a furanyl group and the monomer polymerized under aqueous acidic conditions. At elevated temperatures (>120 C), the polymer undergoes retro Diels-Alder reaction with release of foran (Equation 1). The deprotected polymer can then be selectively crosslinked by a forward Diels-Alder reaction (in the presence of a co-reactant having two or more dime functionalities).

As part of a project for the Defense Advanced Research Projects Agency, Sandia National Laboratories is developing and testing the feasibility of using of a cooperative team of robotic sentry vehicles to guard a perimeter and to perform surround and diversion tasks. This paper describes on-going activities in the development of these robotic sentry vehicles. To date, we have developed a robotic perimeter detection system which consists of eight ''Roving All Terrain Lunar Explorer Rover'' (RATLER{trademark}) vehicles, a laptop-based base-station, and several Miniature Intrusion Detection Sensors (MIDS). A radio frequency receiver on each of the RATLER vehicles alerts the sentry vehicles of alarms from the hidden MIDS. When an alarm is received, each vehicle decides whether it should investigate the alarm based on the proximity of itself and the other vehicles to the alarm. As one vehicle attends an alarm, the other vehicles adjust their position around the perimeter to better prepare for another alarm. We have also demonstrated the ability to drive multiple vehicles in formation via tele-operation or by waypoint GPS navigation. This is currently being extended to include mission planning capabilities. At the base-station, the operator can draw on an aerial map the goal regions to be surrounded and the repulsive regions to be avoided. A potential field path planner automatically generates a path from the vehicles' current position to the goal regions while avoiding the repulsive regions and the other vehicles. This path is previewed to the operator before the regions are downloaded to the vehicles. The same potential field path planner resides on the vehicle, except additional repulsive forces from on-board proximity sensors guide the vehicle away from unplanned obstacles.

This report summarizes a three year effort to develop an automated microassembly workcell for the assembly of LIGA (Lithography Galvonoforming Abforming) parts. Over the last several years, Sandia has developed processes for producing surface machined silicon and LIGA parts for use in weapons surety devices. Some of these parts have outside dimensions as small as 100 micron, and most all have submicron tolerances. Parts this small and precise are extremely difficult to assembly by hand. Therefore, in this project, we investigated the technologies required to develop a robotic workcell to assembly these parts. In particular, we concentrated on micro-grippers, visual servoing, micro-assembly planning, and parallel assembly. Three different micro-grippers were tested: a pneumatic probe, a thermally actuated polysilicon tweezer, and a LIGA fabricated tweezer. Visual servoing was used to accuracy position two parts relative to one another. Fourier optics methods were used to generate synthetic microscope images from CAD drawings. These synthetic images are used off-line to test image processing routines under varying magnifications and depths of field. They also provide reference image features which are used to visually servo the part to the desired position. We also investigated a new aspect of fine motion planning for the micro-domain. As parts approach 1-10 {micro}m or less in outside dimensions, interactive forces such as van der Waals and electrostatic forces become major factors which greatly change the assembly sequence and path plans. We developed the mathematics required to determine the goal regions for pick up, holding, and release of a micro-sphere being handled by a rectangular tool. Finally, we implemented and tested the ability to assemble an array of LIGA parts attached to two 3 inch diameter wafers. In this way, hundreds of parts can be assembled in parallel rather than assembling each part individually.

The robustness of procedures for identifying patterns in scatterplots generated in Monte Carlo sensitivity analyses is investigated. These procedures are based on attempts to detect increasingly complex patterns in the scatterplots under consideration and involve the identification of (1) linear relationships with correlation coefficients, (2) monotonic relationships with rank correlation coefficients, (3) trends in central tendency as defined by means, medians and the Kruskal-Wallis statistic, (4) trends in variability as defined by variances and interquartile ranges, and (5) deviations from randomness as defined by the chi-square statistic. The following two topics related to the robustness of these procedures are considered for a sequence of example analyses with a large model for two-phase fluid flow: the presence of Type I and Type II errors, and the stability of results obtained with independent Latin hypercube samples. Observations from analysis include: (1) Type I errors are unavoidable, (2) Type II errors can occur when inappropriate analysis procedures are used, (3) physical explanations should always be sought for why statistical procedures identify variables as being important, and (4) the identification of important variables tends to be stable for independent Latin hypercube samples.

Abstract not provided.

Abstract not provided.

The ALEGRA radiation transport package implements diffusion, flux-limited diffusion, and SPn radiation transport for both gray and multigroup photon spectra. Comparisons of ALEGRA calculations with known solutions for a selection of benchmark problems for these transport theories are presented. ALEGRA returns accurate solutions in each case. This verifies that each transport theory has been implemented correctly, though it does not prove that the transport theories are valid for problems of interest at Sandia. A validation study will be presented in a future report.

This report represents the completion of a three-year Laboratory-Directed Research and Development (LDRD) program that focused on research and development of GaN-based wide bandgap semiconductor materials (referred to as III-N materials). Our theoretical investigations include the determination of fundamental materials parameters from first-principles calculations, the study of gain properties of III-N heterostructures using a microscopic laser theory and density-functional-theory, charge-state calculations to determine the core structure and energy levels of dislocations in III-N materials. Our experimental investigations include time-resolved photoluminescence and magneto-luminescence studies of GaN epilayers and multiquantum well samples as well as x-ray diffraction studies of AlGaN ternary alloys. In addition, we performed a number of experiments to determine how various materials processing steps affect both the optical and electrical properties of GaN-based materials. These studies include photoluminescence studies of GaN epilayers after post-growth rapid thermal annealing, ion implantation to produce n- and p-type material and electrical and optical studies of plasma-etched structures.

Abstract not provided.

The performance of a solar cell is critically dependent on absorption of incident photons and their conversion into electrical current. This report describes research efforts that have been directed toward the use of nanoscale surface texturing techniques to enhance light absorption in Si. This effort has been divided into two approaches. The first is to use plasma-etching to produce random texturization on multicrystalline Si cells for terrestrial use, since multicrystalline Si cannot be economically textured in any other way. The second approach is to use interference lithography and plasma-etching to produce gettering structures on Si cells for use in space, so that long-wavelength light can be absorbed close to the junction and make the cells more resistant to cosmic radiation damage.

This report reviews a number of issues specific to stand-alone AC lighting systems. A review of AC lighting technology is presented, which discusses the advantages and disadvantages of various lamps. The best lamps for small lighting systems are compact fluorescent. The best lamps for intermediate-size systems are high- or low-pressure sodium. Specifications for battery charging and load control are provided with the goal of achieving lamp lifetimes on the order of 16,000 to 24,000 hours and battery lifetimes of 4 to 5 years. A rough estimate of the potential domestic and global markets for stand-alone AC lighting systems is presented. DC current injection tests were performed on high-pressure sodium lamps and the test results are presented. Finally, a prototype system was designed and a prototype system controller (with battery charger and DC/AC inverter) was developed and built.

Abstract not provided.

Sandia National Laboratories, New Mexico, conducts the Energy Storage Systems Program, which is sponsored by the U.S. Department of Energy's Office of Power Technologies. The goal of this program is to collaborate with industry in developing cost-effective electric energy storage systems for many high-value stationary applications. Sandia National Laboratories is responsible for the engineering analyses, contracted development and testing of energy storage components and systems. This report details the technical achievements realized during fiscal year 1998.

We report on the application of the one-level FETI method to the solution of a class of substructural problems associated with the Department of Energy's Accelerated Strategic Computing Initiative (ASCI). We focus on numerical and parallel scalability issues, and on preliminary performance results obtained on the ASCI Option Red supercomputer configured with as many as one thousand processors, for problems with as many as 5 million degrees of freedom.

Optical spectroscopic techniques were evaluated as nondestructive monitors of the aging of parachutes in nuclear weapons. We analyzed thermally aged samples of nylon and Kevlar webbing by photoluminescence spectroscopy and reflection spectroscopy. Infrared analysis was also performed to help understand the degradation mechanisms of the polymer materials in the webbing. The photoluminescence and reflection spectra were analyzed by chemometric data treatment techniques to see if aged-induced changes in the spectra correlated to changes in measured tensile strength. A correlation was found between the shapes of the photoluminescent bands and the measured tensile strengths. Photoluminescent spectra can be used to predict the tensile strengths of nylon and Kevlar webbing with sufficient accuracy to categorize the webbing sample as above rated tensile strength, marginal or below rated tensile strength. The instrumentation required to perform the optical spectroscopic measurement can be made rugged, compact and portable. Thus, optical spectroscopic techniques offer a means for nondestructive field monitoring of parachutes in the enduring stockpile/

Lost Circulation is a widespread problem encountered when drilling geothermal wells, and often represents a substantial portion of the cost of drilling a well. The U.S. Department of Energy sponsors research and development work at Sandia National Laboratories in an effort to reduce these lost circulation expenditures. Sandia has developed a down hole tool that improves the effectiveness and reduces th cost of lost circulation cement treatment while drilling geothermal wells. This tool, the Drillable Straddle Packer, is a low-cost disposable device that is used to isolate the loss zone and emplace the cement treatment directly into the region of concern. This report documents the design and development of the Drillabe Straddle Packer, the laboratory and field test results, and the design package that is available to transfer this technology to industry users.

This reports summarizes the results from a Laboratory Directed Research and Development effort to develop selective coastings for detecting high priority analytes (HPAs), such as chemical warfare (CW) agents and their precursors, in the presence of common interferents. Accomplishments during this project included synthesis and testing of new derivatized sol-gel coatings for surface acoustic wave sensors (SAWs). Surfactant modified and fluoroalcohol derivatized sol-gel oxides were coated onto SAW devices and tested with volatile organic compounds (VOCs). Theses modified sol-gel coatings improved SAW sensitivity to DMMP by over three orders of magnitude when compared to standard polymeric oatings such as polyisobutylene and by over two orders of magnitude compared with polymers tailor made for enhanced sensitivity to phosphonates. SAW sensors coated with these materials exhibit highly sensitive reversible behavior at elevated temperatures (>90 degree C), possibly leading to low detection levels for semivolatile analytes while remaining insensitive to volatile organic interferants. Additionally, we have investigated the use of reactive polymers for detection of volatile and reactive CW agent precursors (Chemical Weapons Convention Schedule 3 Agents) such as phosphouous oxychloride (POCl(3)). The results obtained in this study find that sensitive and selective responses can be obtained for Schedule 3 agents using commercially available polymers and chemical guidelines from solution phase chemistry.

The objective of this reseach is the investigation of alternative methods for characterizing the reliability of systems with time dependent failure modes associated with stockpile aging. Reference to 'reliability degradation' has, unfortunately, come to be associated with all types of aging analyes: both deterministic and stochastic. In this research, in keeping with the true theoretical definition, reliability is defined as a probabilistic description of system performance as a funtion of time. Traditional reliability methods used to characterize stockpile reliability depend on the collection of a large number of samples or observations. Clearly, after the experiments have been performed and the data has been collected, critical performance problems can be identified. A Major goal of this research is to identify existing methods and/or develop new mathematical techniques and computer analysis tools to anticipate stockpile problems before they become critical issues. One of the most popular methods for characterizing the reliability of components, particularly electronic components, assumes that failures occur in a completely random fashion, i.e. uniformly across time. This method is based primarily on the use of constant failure rates for the various elements that constitute the weapon system, i.e. the systems do not degrade while in storage. Experience has shown that predictions based upon this approach should be regarded with great skepticism since the relationship between the life predicted and the observed life has been difficult to validate. In addition to this fundamental problem, the approach does not recognize that there are time dependent material properties and variations associated with the manufacturing process and the operational environment. To appreciate the uncertainties in predicting system reliability a number of alternative methods are explored in this report. All of the methods are very different from those currently used to assess stockpile reliability, but have been used extensively in various forms outside Sandia National Laboratories. It is hoped that this report will encourage the use of 'nontraditional' reliabilty and uncertainty techniques in gaining insight into stockpile reliability issues.

In February 1997, under the auspices of the Product Realization Program, an initiative to develop performance models for lithium/manganese dioxide-based batteries began. As a part of this initiative, the performance characteristics of the cells under a variety of conditions were determined, both for model development and for model validation. As a direct result of this work, it became apparent that possible Defense Program (DP) uses for batteries based on this cell chemistry existed. A larger effort aimed at mapping the performance envelope of this chemistry was initiated in order to assess the practicality of this cell chemistry, not only for DP applications, but also for other uses. The work performed included an evaluation of the cell performance as a function of a number of variables, including cell size, manufacturer, current, pulse loads, constant current loads, safety, etc. In addition, the development of new evaluation techniques that would apply to any battery system, such as those related to reliability assessments began. This report describes the results of these evaluations.

Macroscopic particles or solid surfaces in contact with a typical low-temperature plasma immediately charge negatively and surround themselves with an electron-depleted region of positive charge. This Debye shielding effect is involved in the Debye-Huckel theory in liquids and plasma sheath formation in the gas phase. In this report, the interaction between such screened particles is found by using the same basic approximation that is used in constructing the Debye shielding potential itself. The results demonstrate that a significant attraction exists between the particles, and, if conditions are right, this attractive force can contribute to the generation of particulate plasma crystals.

We describe the development of a new technology for cooling microelectronics. This report documents the design, fabrication, and prototype testing of micro scale heat pipes embedded in a flat plate substrate or heat spreader. A thermal model tuned to the test results enables us to describe heat transfer in the prototype, as well as evaluate the use of this technology in other applications. The substrate walls are Kovar alloy, which has a coefficient of thermal expansion close to that of microelectronic die. The prototype designs integrating micro heat pipes with Kovar enhance thermal conductivity by more than a factor of two over that of Kovar alone, thus improving the cooling of micro-electronic die.

We have developed high power vertical cavity surface emitting lasers (VCSELS) for multimode or single mode operation. We have characterized new cavity designs for individual lasers and 2-dimensional VCSEL arrays to maximize output power. Using broad area high power VCSELS under pulsed excitation, we have demonstrated the triggering of a photoconductive semiconductor switch (PCSS) with a VCSEL. We also have developed designs for high output power in a single mode. The first approach is to engineer the oxide aperture profile to influence the optical confinement and thus modal properties. A second approach focuses on "leaky-mode" concepts using lateral modification of the cavity resonance to provide the lateral refractive index difference. To this end, we have developed a regrowth process to fabricate single-mode VCSELS. The overall objective of this work was to develop high-power single-mode or multimode sources appropriate for many applications leveraging the many inherent advantages of VCSELS.

The PLD11 board is a 9U VME board containing 11 Altera 10K100 Programmable Logic Devices, controlled impedance clock tree, VME interface, programming inteface, 0C3 (155 Mbps) interface and serial port. The 11 Altera 10K100 Programmable Logic Devices arranged to provide four 96 bit wide buses for a total of 384 parallel digital data lines in and out of the board that can operate up to 100 Mhz for a aggrigate throughput of 38.4 Gpbs. The 14.44 X 15.75 board has over 1.1 million programmable gates that can be programmed through a serial interace. The board contains a clock reference and 50 ohm clock distribution tree that can drive each of the eleven 10K100 devices with two critically timed clock references. Five external clock references can be used to drive five additional PLD 11 boards for a total of six boards operating all from the same synchronous clock reference. A system of six boards provides just under 7 million programmable gates.

The Board-to-Board Optical Interconnect LDRD has successfully developed multiple free space optical interconnect technology based on Sandia developed low threshold VCSEL technology. During the past three years, Sandia has successfully demonstrated low power free space optical links operating at over 100 Mbps for several applications including a prototype weapon interface and a 4.8 Gbps VME board interconnect. A prototype weapon interface using low power VCSELs, InP receivers, and multiple element solar cells was successfully demonstrated. A low power, CMOS compatible 8x8 receiver array having integrated MIM detectors at 830 nm was developed Sandia has successfully demonstrated a low power, light weight pointing mechanism using Rainbow piezoelectric actuators. Robust, low-power, free-space optical interconnects can provide a viable solution to the problem of high bandwidth interconnects between printed circuit boards in a system.

Inversion of head wave arrival times for three-dimensional (3D) planar structure is formulated as a constrained parameter optimization problem, and solved via linear programming techniques. The earth model is characterized by a set of homogeneous and isotropic layers bounded by plane, dipping interfaces. Each interface may possess arbitrary strike and dip. Predicted data consists of traveltimes of critically refracted waves formed on the plane interfaces of the model. The nonlinear inversion procedure is iterative; an initial estimate of the earth model is refined until an acceptable match is obtained between observed and predicted data. Inclusion of a priori constraint information, in the form of inequality relations satisfied by the model parameters, assists the algorithm in converging toward a realistic solution. Although the 3D earth model adopted for the inversion procedure is simple, the algorithm is quite useful in two particular contexts: (i) it can provide an initial model estimate suitable for subsequent improvement by more general techniques (i.e., traveltime tomography), and (ii) it is an effective analysis tool for investigating the power of areal recording geometries for detecting and resolving 3D dipping planar structure.

Lueders' bands are shear deformation features commonly observed in rock specimens that have been deformed experimentally in the brittle-ductile transition regime. For specimens that contain both faults (shear fractures that separate the specimen) and bands, the bands form earlier in the deformation history and their orientations are often different from the fault These differences pose the question of the relationship between these two structures. Understanding the origin of these features may shed light on the genesis of apparent natural analogues, and on the general process of rock deformation and fracture in the laboratory. This paper presents a hypothesis for the formation of Lueders' bands in laboratory specimens based on deformation localization theory considered in the context of the nonuniform stress distribution of the conventional triaxial experiment Lueders' bands and faults appear to be equivalent reflections of the localization process as it is controlled by nonuniform distributions of stress and evolution of incremental constitutive parameters resulting from increasing damage. To relate conditions for localization in laboratory specimens to natural settings, it will be necessary to design new experiments that create uniform stress and deformation fields, or to extract constitutive data indirectly from standard experiments using computational means.

Four different F{sub 2}-based gases (SF{sub 6}, NF{sub 3}, PF{sub 5}, and BF{sub 3}) were examined for high rate Inductively Coupled Plasma etching of Si. Etch rates up to {approximately}8 {micro}m/min were achieved with pure SF{sub 6} discharges at high source power (1500W) and pressure (35mTorr). A direct comparison of the four feedstock gases under the same plasma conditions showed the Si etch rate to increase in the order BF{sub 3} < NF{sub 3} < PF{sub 5} < SF{sub 6}. This is in good correlation with the average bond energies of the gases, except for NF{sub 3}, which is the least strongly bound. Optical emission spectroscopy showed that the ICP source efficiently dissociated NF{sub 3}, but the etched Si surface morphologies were significantly worse with this gas than with the other 3 gases.

Acoustic data are often required for the determination of launch and powered flight loads for rocket systems and payloads. Such data are usually acquired during test firings of the solid rocket motors. In the current work, these data were obtained for two tests at a remote test facility where we were visitors. This paper describes the data acquisition and the requirements for working at a remote site, interfacing with the test hosts.

Application of nanotechnology and advanced optical structures offer new possibilities for improved radiation tolerance in silicon solar cells. We describe the application of subwavelength diffractive structures to enhance optical absorption near the surface, and thereby improve the radiation tolerance.

In this paper, we have presented the relative advantages and complementary aspects of acoustic and seismic ground sensors. A detailed description of both acoustic and seismic ground sensing methods has been provided. Acoustic and seismic phenomenology including source mechanisms, propagation paths, attenuation, and sensing have been discussed in detail. The effects of seismo-acoustic and acousto-seismic interactions as well as recommendations for minimizing seismic/acoustic cross talk have been highlighted. We have shown representative acoustic and seismic ground sensor data to illustrate the advantages and complementary aspects of the two modalities. The data illustrate that seismic transducers often respond to acoustic excitation through acousto-seismic coupling. Based on these results, we discussed the implications of this phenomenology on the detection, identification, and localization objectives of unattended ground sensors. We have concluded with a methodology for selecting the preferred modality (acoustic and/or seismic) for a particular application.

Surface micromachining generally offers more design freedom than related technologies, and it is the technology of choice for most microelectromechanical applications that require multi-level structures. However, the design flexibility that surface micromachining offers is not without limitations. In addition to determining how to fabricate devices in a planar world, the designer also needs to consider issues such as film quality, thickness, residual stress, topography propagation, stringers, processing limitations, and concerns about surface adhesion [1]. Only a few years ago, these were the types of issues that limited design complexity. As the technology improved, the number of mechanical layers available to the designer became the dominant constraint on system functionality. In response, we developed a 5-level polysilicon fabrication technology [2] that offers an unprecedented level of microelectromechanical complexity with simultaneous increases in system yield and robustness. This paper outlines the application that was the driving force behind this work and describes the first devices specifically designed for and fabricated in this technology. The 5-level fabrication technology developed to support this program is known as SUMMiT-V. Four mechanical layers of polysilicon referred to as polyl, poly2, poly3, and poly4 are fabricated above a polyO electrical interconnect and ground plane layer [2,4]. PolyO is 0.3 pm thick, polyl is 1.0 pm, poly 2 is 1.5 pm, and both poly3 and poly4 are 2.25 pm. All films except polyl and poly2 are separated by 2-pm thick depositions of sacrificial oxide. A 0.5-m sacrificial oxide between polyl and poly2 typically defines the clearance between close mating parts such as hubs and hinges. This entire stack is built on a single crystal substrate with a dielectric foundation of 0.8 pm of nitride over 0.63 m of oxide. Seventeen drawing layer are combined to generate the 14 photolithographic masks used to pattern these films during a 240-step fabrication sequence. Mirror Operation To become operational, both mirrors must be driven up to a 45 degree angle. In this position, optical energy entering through an opening in the substrate beneath one mirror [5] is redirected to the second mirror, then down through another substrate opening and onto the target receiver. Each mirror is actuated through a chain of gears driven by a mirror control engine. This chain incorporates a series of gear reduction units that significantly increase drive torque and positional resolution. Also included in this chain are two gears that are not coupled to each other (see figure 3). This prevents the mirror control engine from driving the rack that actuates the mirror. To complete the drive train, two additional gears must be inserted between the interrupted gear pair [4]. The coupling gears that perform this function are shown in figure 4. Both of these gears are fabricated on a plate that moves towards the interrupted pair of gears as the discrimination sequence The plate onto which the coupling gears are fabricated is attached to the left end of the maze rack, so it moves as the rack moves. If the wrong path is taken at any of the 24 decision points in the maze, the coupling gears will not move far enough to complete the mirror gear chain, and the mirror can never be operated. Thus, this is a single attempt device with more than 16 million possible code sequences.

The trend in commercial electronics packaging to deliver ever smaller component packaging has enabled the development of new highly integrated modules meeting the demands of the next generation nano satellites. At under ten kilograms, these nano satellites will require both a greater density electronics and a melding of satellite structure and function. Better techniques must be developed to remove the subsequent heat generated by the active components required to-meet future computing requirements. Integration of commercially available electronics must be achieved without the increased costs normally associated with current generation multi chip modules. In this paper we present a method of component integration that uses silicon heat pipe technology and advanced flexible laminate circuit board technology to achieve thermal control and satellite structure. The' electronics/heat pipe stack then becomes an integral component of the spacecraft structure. Thermal management on satellites has always been a problem. The shrinking size of electronics and voltage requirements and the accompanying reduction in power dissipation has helped the situation somewhat. Nevertheless, the demands for increased onboard processing power have resulted in an ever increasing power density within the satellite body. With the introduction of nano satellites, small satellites under ten kilograms and under 1000 cubic inches, the area available on which to place hot components for proper heat dissipation has dwindled dramatically. The resulting satellite has become nearly a solid mass of electronics with nowhere to dissipate heat to space. The silicon heat pipe is attached to an aluminum frame using a thermally conductive epoxy or solder preform. The frame serves three purposes. First, the aluminum frame provides a heat conduction path from the edge of the heat pipe to radiators on the surface of the satellite. Secondly, it serves as an attachment point for extended structures attached to the satellite such as solar panels, radiators, antenna and.telescopes (for communications or sensors). Finally, the packages make thermal contact to the surface of the silicon heat pipe through soft thermal pads. Electronic components can be placed on both sides of the flexible circuit interconnect. Silicon heat pipes have a number of advantages over heat pipe constructed from other materials. Silicon heat pipes offer the ability to put the heat pipe structure beneath the active components of a processed silicon wafer. This would be one way of efficiently cooling the heat generated by wafer scale integrated systems. Using this technique, all the functions of a satellite could be reduced to a few silicon wafers. The integration of the heat pipe and the electronics would further reduce the size and weight of the satellite.

Abstract not provided.

Three-dimensional unstructured tetrahedral and hexahedral finite element mesh optimization is studied from a theoretical perspective and by computer experiments to determine what objective functions are most effective in attaining valid, high quality meshes. The approach uses matrices and matrix norms to extend the work in Part I to build suitable 3D objective functions. Because certain matrix norm identities which hold for 2 x 2 matrices do not hold for 3 x 3 matrices. significant differences arise between surface and volume mesh optimization objective functions. It is shown, for example, that the equivalence in two-dimensions of the Smoothness and Condition Number of the Jacobian matrix objective functions does not extend to three dimensions and further. that the equivalence of the Oddy and Condition Number of the Metric Tensor objective functions in two-dimensions also fails to extend to three-dimensions. Matrix norm identities are used to systematically construct dimensionally homogeneous groups of objective functions. The concept of an ideal minimizing matrix is introduced for both hexahedral and tetrahedral elements. Non-dimensional objective functions having barriers are emphasized as the most logical choice for mesh optimization. The performance of a number of objective functions in improving mesh quality was assessed on a suite of realistic test problems, focusing particularly on all-hexahedral ''whisker-weaved'' meshes. Performance is investigated on both structured and unstructured meshes and on both hexahedral and tetrahedral meshes. Although several objective functions are competitive, the condition number objective function is particularly attractive. The objective functions are closely related to mesh quality measures. To illustrate, it is shown that the condition number metric can be viewed as a new tetrahedral element quality measure.

Scanning probe microscopy (SPM) techniques are not suitable as global defect-localization tools. They can, however, pinpoint the exact location of the defects once the approximate locations of the defects have been identified by other failure analysis techniques. SPM techniques also provide information such as 3-D topology, current, surface potential, and 2-D dopant profile that may not be readily obtainable with other techniques. This information, coupled with the unparalleled spatial resolution and high detection sensitivity can be used by failure analysts for root cause analysis.

This paper reports the successful bonding of 8 x 8 and 4 x 4 VCSEL arrays to Si CMOS and GaAs MESFET integrated circuits and to GaAs substrates. Three different bonding techniques are demonstrated and their electrical, optical and mechanical characteristics are compared. All three techniques remove the substrate from the VCSEL wafer, leaving individual VCSELs bonded directly to locations within the integrated circuit.

In this paper, the authors quantify how communication increases the effective range of detection of unattended ground sensors. Statistical analysis used to evaluate the probability of detection for multiple sensors using one, two, and infinite levels of cooperation. levels of cooperation are defined as the levels of communication between sensors. One level of cooperation means that one sensor passes its state information to several other sensors within a limited communication range, but this information is not passed beyond this range. Two levels of cooperation means that the state information received by this first set of sensors is relayed to another set of sensors within their communication range. Infinite levels of cooperation means that the state information is further percolated out to all sensors within a communicating group. With large numbers of sensors, every sensor will have state information about every other sensor regardless of communication range. With smaller numbers of sensors, isolated groups may form, thus lowering the probability of information transfer.

Important factors in the application of chemical sensing technology to space applications are low mass, small size, and low power. All of these attributes are enabled by the application of MEMS and micro-fabrication technology to chemical sensing. Several Sandia projects that apply these technologies to the development of new chemical sensing capabilities with the potential for space applications will be described. The Polychromator project is a joint project with Honeywell and MIT to develop an electrically programmable diffraction grating that can be programmed to synthesize the spectra of molecules. This grating will be used as the reference cell in a gas correlation radiometer to enable remote chemical detection of most chemical species. Another area of research where micro-fabrication is having a large impact is the development of a lab on a chip. Sandia's efforts to develop the {mu}ChemLab{trademark} will be described including the development of microfabricated pre-concentrators, chromatographic columns, and detectors. Chemical sensors are evolving in the direction of sensor arrays with pattern recognition methods applied to interpret the pattern of response. Sandia's development of micro-fabricated chemiresistor arrays and the VERI pattern recognition technology to interpret the sensor response will be described.

The packaging of Micro-Electro-Mechanical Systems (MEMS) is a field of great importance to anyone using or manufacturing sensors, consumer products, or military applications. Currently much work has been done in the design and fabrication of MEMS devices but insufficient research and few publications have been completed on the packaging of these devices. This is despite the fact that packaging is a very large percentage of the total cost of MEMS devices. The main difference between IC packaging and MEMS packaging is that MEMS packaging is almost always application specific and greatly affected by its environment and packaging techniques such as die handling, die attach processes, and lid sealing. Many of these aspects are directly related to the materials used in the packaging processes. MEMS devices that are functional in wafer form can be rendered inoperable after packaging. MEMS dies must be handled only from the chip sides so features on the top surface are not damaged. This eliminates most current die pick-and-place fixtures. Die attach materials are key to MEMS packaging. Using hard die attach solders can create high stresses in the MEMS devices, which can affect their operation greatly. Low-stress epoxies can be high-outgassing, which can also affect device performance. Also, a low modulus die attach can allow the die to move during ultrasonic wirebonding resulting to low wirebond strength. Another source of residual stress is the lid sealing process. Most MEMS based sensors and devices require a hermetically sealed package. This can be done by parallel seam welding the package lid, but at the cost of further induced stress on the die. Another issue of MEMS packaging is the media compatibility of the packaged device. MEMS unlike ICS often interface with their environment, which could be high pressure or corrosive. The main conclusion we can draw about MEMS packaging is that the package affects the performance and reliability of the MEMS devices. There is a gross lack of understanding between the package materials, induced stress, and the device performance. The material properties of these packaging materials are not well defined or understood. Modeling of these materials and processes is far from maturity. Current post-package yields are too low for commercial feasibility, and consumer operating environment reliability and compatibility are often difficult to simulate. With further understanding of the materials properties and behavior of the packaging materials, MEMS applications can be fully realized and integrated into countless commercial and military applications.

It is likely that aging is affecting the radiation hardness of stockpile electronics, and we have seen apparent examples of aging that affects the electronic radiation hardness. It is also possible that low-level intrinsic radiation that is inherent during stockpile life will damage or in a sense age electronic components. Both aging and low level radiation effects on radiation hardness and stockpile reliability need to be further investigated by using both test and modeling strategies that include appropriate testing of electronic components withdrawn from the stockpile.

Procedures for identifying patterns in scatterplots generated in Monte Carlo sensitivity analyses are described and illustrated. These procedures attempt to detect increasingly complex patterns in scatterplots and involve the identification of (i) linear relationships with correlation coefficients, (ii) monotonic relationships with rank correlation coefficients, (iii) trends in central tendency as defined by means, medians and the Kruskal-Wallis statistic, (iv) trends in variability as defined by variances and interquartile ranges, and (v) deviations from randomness as defined by the chi-square statistic. A sequence of example analyses with a large model for two-phase fluid flow illustrates how the individual procedures can differ in the variables that they identify as having effects on particular model outcomes. The example analyses indicate that the use of a sequence of procedures is a good analysis strategy and provides some assurance that an important effect is not overlooked.

Probabilistic uncertainty is a phenomenon that occurs to a certain degree in many engineering applications. The effects that this uncertainty has upon a given system response are a matter of some concern. Techniques which provide insight to these effects will be required as modeling and prediction becomes a more vital tool in the engineering design process. The purpose of this paper is to outline a procedure to evaluate uncertainty in dynamic system response exploiting various numerical methods. Specifically, the goal is to attain the statistics of the response with minimal computational effort. Numerical interpolation and integration techniques are utilized in conjunction with the iterative form of the Advanced Mean Value (AMV+) method to efficiently and accurately estimate statistical moments of the response random process. A numerical example illustrating the use of this analytical tool in a practical framework is presented.

ATHEANA, a second-generation Human Reliability Analysis (HRA) method integrates advances in psychology with engineering, human factors, and Probabilistic Risk Analysis (PRA) disciplines to provide an HRA quantification process and PRA modeling interface that can accommodate and represent human performance in real nuclear power plant events. The method uses the characteristics of serious accidents identified through retrospective analysis of serious operational events to set priorities in a search process for significant human failure events, unsafe acts, and error-forcing context (unfavorable plant conditions combined with negative performance-shaping factors). ATHEANA has been tested in a demonstration project at an operating pressurized water reactor.

Nanostructured particles exhibiting well-defined pore sizes and pore connectivities (1-, 2-, or 3-dimensional) are of interest for catalysis, chromatography, controlled release, low dielectric constant fillers, and custom-designed pigments and optical hosts. During the last several years considerable progress has been made on controlling the macroscopic forms of mesoporous silicas prepared by surfactant and block copolymer liquid crystalline templating procedures. Typically interfacial phenomena are used to control the macroscopic form (particles, fibers, or films), while self-assembly of amphiphilic surfactants or polymers is used to control the mesostructure. To date, although a variety of spherical or nearly-spherical particles have been prepared, their extent of order is limited as is the range of attainable mesostructures. They report a rapid, aerosol process that results in solid, completely ordered spherical particles with stable hexagonal, cubic, or vesicular mesostructures. The process relies on evaporation-induced interfacial self-assembly (EISA) confined to a spherical aerosol droplet. The process is simple and generalizable to a variety of materials combinations. Additionally, it can be modified to provide the first aerosol route to the formation of ordered mesostructured films.

In two recent publications relativistic electron flow in cylindrical magnetically-insulated transmission lines (MITL) was analyzed and modeled under the assumption of negligible electron pressure. Cylindrical MITLs were used because of their common occurrence, and because they are the simplest case of finite width. The authors show in this report that the models apply equally to MITLs of any cross section.

The role of hydrogen in enhancing the photoluminescence (PL) yield observed from Si nanocrystals embedded in SiO{sub 2} has been studied. SiO{sub 2} thermal oxides and bulk fused silica samples have been implanted with Si and subsequently annealed in various ambients including hydrogen or deuterium forming gases (Ar+4%H{sub 2} or Ar+4%D{sub 2}) or pure Ar. Results are presented for annealing at temperatures between 200 and 1100 C. Depth and concentration profiles of H and D at various stages of processing have been measured using elastic recoil detection. Hydrogen or deuterium is observed in the bulk after annealing in forming gas but not after high temperature (1100 C) anneals in Ar. The presence of hydrogen dramatically increases the broad PL band centered in the near-infrared after annealing at 1100 C but has almost no effect on the PL spectral distribution. Hydrogen is found to selectively trap in the region where Si nanocrystals are formed, consistent with a model of H passivating surface states at the Si/SiO{sub 2} interface that leads to enhanced PL. The thermal stability of the trapped H and the PL yield observed after a high temperature anneal have been studied. The hydrogen concentration and PL yield are unchanged for subsequent anneals up to 400 C. However, above 400 C the PL decreases and a more complicated H chemistry is evident. Similar concentrations of H or D are trapped after annealing in H{sub 2} or D{sub 2} forming gas; however, no differences in the PL yield or spectral distribution are observed, indicating that the electronic transitions resulting in luminescence are not dependent on the mass of the hydrogen species.

The effect of excluded volume on the coil size of dilute linear polymers was investigated by off-lattice Monte Carlo simulations. The radius of gyration R{sub g} was evaluated for a wide range of chain lengths at several temperatures and at the athermal condition. The theta temperature and the corresponding theta chain dimensions were established for the system, and the dependence of the size expansion factor, a{sub s} = R{sub g} /(R{sub g}){sub {theta}}, on chain length N and temperature T was examined. For long chains and at high temperatures, a{sub s} is a function of N/N{sub s}{sup 2} alone, where the length scale N{sub s}{sup 2} depends only on T. The form of this simulations-based master function compares favorably with {alpha}{sub s}(M/M{sub s}{sup 2}), an experimental master curve for linear polymers in good solvents, where M{sub s}{sup 2} depends only on polymer-solvent system. Comparisons when N{sub s}{sup 2}(T) and M{sub s}{sup 2}(system) are reduced to common units, numbers of Kuhn steps, strongly indicate that coil expansion in even the best of good solvents is small relative to that expected for truly athermal solutions. An explanation for this behavior is proposed, based on what would appear to be an inherent difference in the equation of state properties for polymeric and monomeric liquids.

Electronic absorption and resonance Raman (RR) spectra of the ferric form of barley grain peroxidase (BP 1) at various pH values both at room temperature and 20 K are . reported, together with EPR spectra at 10 K. The ferrous forms and the ferric complex with fluoride have also been studied. A quantum mechanically mixed-spin (QS) state has been identified. The QS heme species co-exists with 6- and 5-cHS heroes; the relative populations of these three spin states are found to be dependent on pH and temperature. However, the QS species remains in all cases the dominant heme spin species. Barley peroxidase appears to be further characterized by a splitting of the two vinyl stretching modes, indicating that the vinyl groups are differently conjugated with the porphyrin. An analysis of the presently available spectroscopic data for proteins from all three peroxidase classes suggests that the simultaneous occurrence of the QS heme state as well as the splitting of the two vinyl stretching modes is confined to class III enzymes. The former point is discussed in terms of the possible influences of heme deformations on heme spin state. It is found that moderate saddling alone is probably not enough to cause the QS state, although some saddling maybe necessary for the QS state.

Nanosatellite space launches could significantly benefit from an electrically powered launch complex, based on an electromagnetic coil launcher. This paper presents results of studies to estimate the required launcher parameters and some fixed facility issues. This study is based on electromagnetic launch, or electromagnetic gun technology, which is constrained to a coaxial geometry to take advantage of the efficiency of closely-coupled coils. A baseline configuration for analysis considers a payload mass of 10 kg, launch velocity of 6 km/s, a second stage solid booster for orbital insertion, and a payload fraction of about 0.1. The launch facility is envisioned as an inclined track, 1-2 km in length, mounted on a hillside at 25 degrees aimed in the orbital inclination of interest. The launcher energy and power requirements fall in the range of 2000 MJ and 2 MW electric. This energy would be supplied by 400 modules of energy storage and magnetic coils. With a prime power generator of 2 MW, a launch rate of some 200 satellites per day is possible. The launch requires high acceleration, so the satellite package must be hardened to launch acceleration on the order of 1000 gee. Parametric evaluations compare performance parameters for a launcher length of 1-2 km, exit velocity of 4-8 km/s, and payloads of 1-100 kg. The EM launch complex could greatly reduce the amount of fuels handling, reduce the turn-around time between launches, allow more concurrence in launch preparation, reduce the manpower requirements for launch vehicle preparation and increase the reliability of launch by using more standardized vehicle preparations. Most importantly, such a facility could reduce the cost per launch and could give true launch-on-demand capability for nanosatellites.

Detailed materials evaluations have been performed for MC2969 Intent Stronglink switch monitor circuit parts returned from the field out of retired weapon systems. Evaluations of local contact resistance, surface chemical composition and surface roughness and wear have been determined as a function of component level contact loop resistance testing position. Several degradation mechanisms have been identified and correlated with the component level measurements. Operational degradation produces surface smoothing and wear with each actuation of the monitor circuit, while aging degradation is observed in the segregation of contaminant species and alloy constituent elements to the surface in the stressed wear regions.

The Waste Isolation Pilot Plant (WIPP) is a US Department of Energy (DOE) facility for the permanent disposal of transuranic waste from defense activities. In 1996, the DOE submitted the Title 40 CFR Part 191 Compliance Certification Application for the Waste Isolation Pilot Plant (CCA) to the US Environmental Protection Agency (EPA). The CCA included a probabilistic performance assessment (PA) conducted by Sandia National Laboratories to establish compliance with the quantitative release limits defined in 40 CFR 191.13. An experimental program to collect data relevant to the actinide source term began around 1989, which eventually supported the 1996 CCA PA actinide source term model. The actinide source term provided an estimate of mobile dissolved and colloidal Pu, Am, U, Th, and Np concentrations in their stable oxidation states, and accounted for effects of uncertainty in the chemistry of brines in waste disposal areas. The experimental program and the actinide source term included in the CCA PA underwent EPA review lasting more than 1 year. Experiments were initially conducted to develop data relevant to the wide range of potential future conditions in waste disposal areas. Interim, preliminary performance assessments and actinide source term models provided insight allowing refinement of experiments and models. Expert peer review provided additional feedback and confidence in the evolving experimental program. By 1995, the chemical database and PA predictions of WIPP performance were considered reliable enough to support the decision to add an MgO backfill to waste rooms to control chemical conditions and reduce uncertainty in actinide concentrations, especially for Pu and Am. Important lessons learned through the characterization, PA modeling, and regulatory review of the actinide source term are (1) experimental characterization and PA should evolve together, with neither activity completely dominating the other, (2) the understanding of physical processes required to develop conceptual models is greater than can be represented in PA models, (3) experimentalists should be directly involved in model and parameter abstraction and simplification for PA, and (4) external expert review should be incorporated early in a project to increase confidence long before regulatory reviews begin.

Under the sponsorship of the Ministry of International Trade and Industry (MITI) of Japan, the Nuclear Power Engineering Corporation (NUPEC) is investigating the seismic behavior of a Reinforced Concrete Containment Vessel (RCCV) through scale-model testing using the high-performance shaking table at the Tadotsu Engineering Laboratory. A series of tests representing design-level seismic ground motions was initially conducted to gather valuable experimental measurements for use in design verification. Additional tests will be conducted with increasing amplifications of the seismic input until a structural failure of the test model occurs. In a cooperative program with NUPEC, the US Nuclear Regulatory Commission (USNRC), through Sandia National Laboratories (SNL), is conducting analytical research on the seismic behavior of RCCV structures. As part of this program, pretest analytical predictions of the model tests are being performed. The dynamic time-history analysis utilizes a highly detailed concrete constitutive model applied to a three-dimensional finite element representation of the test structure. This paper describes the details of the analysis model and provides analysis results.

Predictive models of solid lubricant performance are needed to determine the dynamic behavior of electromechanical devices after long periods of storage. X-ray photoelectron spectroscopy has been used to determine the kinetics of oxidation and sulfate formation for solid lubricants and self-lubricating materials containing MoS{sub 2}, exposed to a variety of oxidation conditions. The frictional performance of the lubricant has then been determined as a fi.mction of its surface chemistry and the ambient environment in which sliding takes place. Results indicate that surface sulfate formation governs the initial or start-up friction coefficient of MoS{sub 2}-containing films, while the composition of the ambient gas determines the steady-state friction coefficient. The dependence of the steady-state friction coefficient on the environment in which sliding takes place has been examined, and the results show that dynamic oxidation of surfaces having exposed metal has a major impact on friction. Surface oxidation is also shown to influence the frictional behavior of a self-lubricating composite material containing MoS{sub 2}.

The use of {sup 17}O NMR spectroscopy as a tool to investigate aging in polymer systems has recently been demonstrated. Because the natural abundance of {sup 17}O is extremely low (0.037%), the use of labeled {sup 17}O{sub 2} during the oxidation of polymers produces {sup 17}O NMR spectra whose signals arise entirely from the degradation species (i.e. signals from the bulk or unaged material are not observed). This selective isotopic labeling eliminates the impact of interference from the unaged material, cause (1) above. As discussed by Alam et al. spectral overlap between different degradation species as well as errors in quantification remains a major difficulty in {sup 17}O NMR spectroscopy. As a demonstration of the DECRA and CTBSA methods, relaxation matrices obtained from {sup 17}O NMR for model alcohol systems are evaluated. The benefits and limitations of these newly developed chemometric techniques are discussed.

A multi-attribute utility analysis is applied to a decision process to select a treatment method for the management of aluminum-based spent nuclear fuel (Al-SNF) owned by the US Department of Energy (DOE). DOE will receive, treat, and temporarily store Al-SNF, most of which is composed of highly enriched uranium, at its Savannah River Site in South Carolina. DOE intends ultimately to send the treated Al-SNF to a geologic repository for permanent disposal. DOE initially considered ten treatment alternatives for the management of Al-SNF, and has narrowed the choice to two of these: the direct disposal and melt and dilute alternatives. The decision analysis presented in this document focuses on a formal decision process used to evaluate these two remaining alternatives.

The author demonstrates the Border Trade Facilitation System (BTFS), an agent-based bilingual e-commerce system built to expedite the regulation, control, and execution of commercial trans-border shipments during the delivery phase. The system was built to serve maquila industries at the US/Mexican border. The BTFS uses foundation technology developed here at Sandia Laboratories' Advanced Information Systems Lab (AISL), including a distributed object substrate, a general-purpose agent development framework, dynamically generated agent-human interaction via the World-Wide Web, and a collaborative agent architecture. This technology is also the substrate for the Multi-Agent Simulation Management System (MASMAS) proposed for demonstration at this conference. The BTFS executes authenticated transactions among agents performing open trading over the Internet. With the BTFS in place, one could conduct secure international transactions from any site with an Internet connection and a web browser. The BTFS is currently being evaluated for commercialization.

The quantum confined Stark effect was found to result in a strong quantum well width dependence of threshold current density in strained group-III nitride quantum well lasers. For an In{sub 0.2}Ga{sub 0.8}N/GaN structure with quantum well width in the neighborhood of 3.5nm, our analysis shows that the reduction in spontaneous emission loss by the electron-hole spatial separation outweighs the corresponding reduction in gain to produce a threshold current density minimum.

Many types of integrated and discrete microelectronic devices exist in the enduring stockpile. In the past, most of these devices have used conventional ceramic hermetic packaging (CHP) technology. Sometime in the future, plastic encapsulated microelectronic (PEM) devices will almost certainly enter the inventory. In the presence of moisture, several of the aluminum-containing metallization features common to both types of packaging become susceptible to atmospheric corrosion (Figure 1). A breach in hermeticity (e.g., due to a crack in the ceramic body or lid seal) could allow moisture and/or contamination to enter the interior of a CHP device. For PEM components, the epoxy encapsulant material is inherently permeable to moisture. A multi-year project is now underway at Sandia to develop the knowledge base and analytical tools needed to quantitatively predict the effect of corrosion on microelectronic performance and reliability. The issue of corrosion-induced failure surfaced twice during the past year because cracks were found in their ceramic bodies of two different CHP devices: the SA371 1/3712 MOSFET and the SA3935 ASIC (acronym for A Simple Integrated Circuit). Because of our inability to perform a model-based prediction at that time, the decision was made to determine the validity of the corrosion concern for these specific situations by characterizing the expected environment and assessing its relative degree of corrosivity. The results of this study are briefly described in this paper along with some of the advancements made with the predictive model development.

We have been working for many years to develop better methods for predicting the lifetimes of polymer materials. Because of the recent interest in extending the lifetimes of nuclear weapons and the importance of environmental seals (o-rings, gaskets) for protecting weapon interiors against oxygen and water vapor, we have recently turned our attention to seal materials. Perhaps the most important environmental o-ring material is butyl rubber, used in various military applications. Although it is the optimum choice from a water permeability perspective, butyl can be marginal from an aging point-of-view. The purpose of the present work was to derive better methods for predicting seal lifetimes and applying these methods to an important butyl material, Parker compound B6 12-70.

The Container Analysis Fire Environment computer code (CAFE) is intended to provide Type B package designers with an enhanced engulfing fire boundary condition when combined with the PATRAN/P-Thermal commercial code. Historically an engulfing fire boundary condition has been modeled as {sigma}T{sup 4} where {sigma} is the Stefan-Boltzman constant, and T is the fire temperature. The CAFE code includes the necessary chemistry, thermal radiation, and fluid mechanics to model an engulfing fire. Effects included are the local cooling of gases that form a protective boundary layer that reduces the incoming radiant heat flux to values lower than expected from a simple {sigma}T{sup 4} model. In addition, the effect of object shape on mixing that may increase the local fire temperature is included. Both high and low temperature regions that depend upon the local availability of oxygen are also calculated. Thus the competing effects that can both increase and decrease the local values of radiant heat flux are included in a reamer that is not predictable a-priori. The CAFE package consists of a group of computer subroutines that can be linked to workstation-based thermal analysis codes in order to predict package performance during regulatory and other accident fire scenarios.

A GaN/AlGaN heterojunction bipolar transistor structure with Mg doping in the base and Si Doping in the emitter and collector regions was grown by Metal Organic Chemical Vapor Deposition in c-axis Al(2)O(3). Secondary Ion Mass Spectrometry measurements showed no increase in the O concentration (2-3x10(18) cm(-3)) in the AlGaN emitter and fairly low levels of C (~4-5x10(17) cm (-3)) throughout the structure. Due to the non-ohmic behavior of the base contact at room temperature, the current gain of large area (~90 um diameter) devices was <3. Increasing the device operating temperature led to higher ionization fractions of the mg acceptors in the base, and current gains of ~10 were obtained at 300 degree C.

The relative density of BCl radicals has been measured in a modified Applied Materials DPS metal etch chamber using laser-induced fluorescence. In plasmas containing mixtures of BCl{sub 3} with Cl{sub 2}, Ar and/or N{sub 2}, the relative BCl density was measured as a function of source and bias power, pressure, flow rate, BCl{sub 3}/Cl{sub 2} ratio and argon addition. To determine the influence of surface materials on the bulk plasma properties, the relative BCl density was measured using four different substrate types; aluminum, alumina, photoresist, and photoresist-patterned aluminum. In most cases, the relative BCl density was highest above photoresist-coated wafers and lowest above blanket aluminum wafers. The BCl density increased with increasing source power and the ratio of BCl{sub 3} to Cl{sub 2}, while the addition of N{sub 2} to a BCl{sub 3}/Cl{sub 2} plasma resulted in a decrease in BCl density. The BCl density was relatively insensitive to changes in the other plasma parameters.

This paper identifies and explores the technical requirements and issues associated with remotely monitoring continuous wave (CW) sources with seismic arrays. Potential approaches to this monitoring problem will be suggested and partially evaluated to expose the monitoring challenges which arise when realistic local geologies and cultural noise sources are considered. The selective directionality and the adaptive noise cancellation properties of arrays are required to observe weak signals while suppressing a colored background punctuated with an unknown distribution of point and sometimes distributive sources. The array is also required to characterize the emitters and propagation environment so as to properly focus on the CW sources of interest while suppressing the remaining emitters. The proper application of arrays requires an appreciation of the complexity of propagation in a non-homogeneous earth. The heterogeneity often limits the available spatial coherence and therefore the size of the army. This adversely impacts the array gain and the array's ability to carefully resolve various emitters. Arrays must also contend with multipath induced by the source and the heterogeneous earth. If the array is to focus on an emitter and realize an enhancement in the signal to noise ratio, methods must be sought to coherently add the desired signal components while suppressing interference which may be correlated with the desired signal. The impact of these and other issues on army design and processing are described and discussed.

Sandia is manufacturing CMOS ICs with 0.5 {micro}m LOCOS and shallow trench isolation (STI) technologies and is developing a 0.35 {micro}m SOI technology. A program based on burn-in and life tests is being used to qualify the 0.5 {micro}m technologies for delivery of high reliability ICs to customers for military and space applications. Representative ICs from baseline wafer lots are assembled using a high reliability process with multilayer hermetic, ceramic packages. These ICs are electrically tested before, during, and after burn-in and subsequent 1000 hour dynamic and static life tests. Two types of ICS are being used for this qualification, a 256K bit SRAM and a Microcontroller Core (MCC). Over 600 ICs have successfully completed these qualification tests, resulting in a failure rate estimate of less than 4 FITS for satellite applications. Recently, a group of SRAMS from a development wafer lot incorporating nonqualified processes of the 0.5 {micro}m LOCOS technology had an unusually high number of failures during the initial electrical test after packaging. The investigation of these failures is described.

Abstract not provided.

Silicide Schottky contacts can be as large as 0.955 eV (E{sub v} + 0.165 eV) on n-type silicon and as large as 1.05 eV (E{sub c} {minus} 0.07 eV) on p-type silicon. Current models of Schottky barrier formation do not provide a satisfactory explanation of occurrence of this wide variation. A model for understanding Schottky contacts via screened pinning at defect levels is presented. In the present paper it is shown that most transition metal silicides are pinned approximately 0.48 eV above the valence band by interstitial Si clusters. Rare earth disilicides pin close to the divacancy acceptor level 0.41 eV below the conduction band edge while high work function silicides of Ir and Pt pin close to the divacancy donor level 0.21 eV above the valence band edge. Selection of a particular defect pinning level depends strongly on the relative positions of the silicide work function and the defect energy level on an absolute energy scale.

Recent space experience has shown that the use of commercial optocouplers can be problematic in spacecraft, such as TOPEX/Poseidon, that must operate in significant radiation environments. Radiation--induced failures of these devices have been observed in space and have been further documented at similar radiation doses in the laboratory. The ubiquitous use of optocouplers in spacecraft systems for a variety of applications, such as electrical isolation, switching and power transfer, is indicative of the need for optocouplers that can withstand the space radiation environment. In addition, the distributed nature of their use implies that it is not particularly desirable to shield optocouplers for use in radiation environments. Thus, it will be important for the space community to have access to radiation hardened/tolerant optocouplers. For many microelectronic and photonic devices, it is difficult to achieve radiation hardness without sacrificing performance. However, in the case of optocouplers, one should be able to achieve both superior radiation hardness and performance for such characteristics as switching speed, current transfer ratio (CTR), minimum power usage and array power transfer, if standard light emitting diodes (LEDs), such as those in the commercial optocouplers mentioned above, are avoided, and VCSELs are employed as the emitter portion of the optocoupler. The physical configuration of VCSELs allows one to achieve parallel use of an array of devices and construct a multichannel optocoupler in the standard fashion with the emitters and detectors looking at each other. In addition, detectors similar in structure to the VCSELs can be fabricated which allows bidirectional functionality of the optocoupler. Recent discussions suggest that VCSELs will enjoy widespread applications in the telecommunications and data transfer fields.

Recent attention has been given to the deployment of an adaptable sensor array realized by multi-robotic systems. Our group has been studying the collective behavior of autonomous, multi-agent systems and their applications in the area of remote-sensing and emerging threats. To accomplish such tasks, an interdisciplinary research effort at Sandia National Laboratories are conducting tests in the fields of sensor technology, robotics, and multi-robotic and multi-agents architectures. Our goal is to coordinate a constellation of point sensors that optimizes spatial coverage and multivariate signal analysis using unmanned robotic vehicles (e.g., RATLERs, Robotic All-ten-sin Lunar Exploration Rover-class vehicles). Overall design methodology is to evolve complex collective behaviors realized through simple interaction (kinetic) physics and artificial intelligence to enable real-time operational responses to emerging threats. This paper focuses on our recent work understanding the dynamics of many-body systems using the physics-based hydrodynamic model of lattice gas automata. Three design features are investigated. One, for single-speed robots, a hexagonal nearest-neighbor interaction topology is necessary to preserve standard hydrodynamic flow. Two, adaptability, defined by the swarm's deformation rate, can be controlled through the hydrodynamic viscosity term, which, in turn, is defined by the local robotic interaction rules. Three, due to the inherent non-linearity of the dynamical equations describing large ensembles, development of stability criteria ensuring convergence to equilibrium states is developed by scaling information flow rates relative to a swarm's hydrodynamic flow rate. An initial test case simulates a swarm of twenty-five robots that maneuvers past an obstacle while following a moving target. A genetic algorithm optimizes applied nearest-neighbor forces in each of five spatial regions distributed over the simulation domain. Armed with knowledge, the swarm adapts by changing state in order to avoid the obstacle. Simulation results are qualitatively similar to lattice gas.

An interferometric technique has been developed for non-destructive, high-confidence, in-situ determination of material properties in MEMS. By using interferometry to measure the full deflection curves of beams pulled toward the substrate under electrostatic loads, the actual behavior of the beams has been modeled. No other method for determining material properties allows such detailed knowledge of device behavior to be gathered. Values for material properties and non-idealities (such as support post compliance) have then been extracted which minimize the error between the measured and modeled deflections. High accuracy and resolution have been demonstrated, allowing the measurements to be used to enhance process control.

The characteristics of a piezoresistive accelerometer in shock environments have been studied at Sandia National Laboratories (SNL) in the Mechanical Shock Testing Laboratory for ten years The SNL Shock Laboratory has developed a capability to characterize accelerometers and other transducers with shocks aligned with the transducer's sensing axis and perpendicular to the transducer's sensing axis. This unique capability includes Hopkinson bars made of aluminum, steel, titanium, and beryllium. The bars are configured as both single and split Hopkinson bars. Four different areas that conclude this study are summarized in this paper: characterization of the cross-axis response of the accelerometer in the four environments of static compression, static strain on a beam, dynamic strain, and mechanical shock, the accelerometer's response on a titanium Hopkinson bar with two 45{degree} flats on the end of the bar; failure analysis of the accelerometer; and measurement of the accelerometer's self-generating cable response in a shock environment.

This paper summarizes recent progress in the development of back-contact crystalline-silicon (c-Si) solar cells and modules at Sandia National Laboratories. Back-contact cells have potentially improved efficiencies through the elimination of grid obscuration and allow for significant simplifications in the module assembly process. Optimization of the process sequence has improved the efficiency of our back-contact cell (emitter wrap through) from around 12% to near 17% in the past 12 months. In addition, recent theoretical work has elucidated the device physics of emitter wrap-through cells. Finally, improvements in the assembly processing back-contact cells are described.

An analytical solution for large deflections of a clamped circular diaphragm with built-in stress is presented. The solution is directly applicable to micromachined pressure sensors. The solution is compared to finite element analysis results and experimental data from a surface-micromachined pressure sensor.

Abstract not provided.

The isochronal anneal technique used to predict isothermal anneal behavior of MOS devices is analyzed as a function of experimental parameters. The effects of detrapping of trapped holes and compensating electrons are discussed.

A hand-held chemical laboratory ({mu}ChemLab) is being developed that utilizes a silicon- nitride-supported microhotplate in the front-end, gas sampling and preconcentration stage. Device constraints include low-power (<200mW at 5V), rapid heating (<20msec), and a relatively uniform temperature distribution throughout the heated area ({approximately}3mm{sup 2}). To optimize for these criteria, the electro-thermal behavior of the microhotplate was modeled using Thermal Analysis System (TAS). Predicted steady-state and transient behavior agree well with infrared (IR) microscope data and measured transient response for a low-stress silicon nitride thermal conductivity of k{sub n} = 6.4 x 10{sup {minus}2} W x (cm x {degree}C){sup {minus}1} and a convection coefficient of h{sub cv} = 3.5 x 10{sup {minus}3} W x (cm{sup 2} x {degree}C){sup {minus}1}. The magnitude of h{sub cv} is framed in the context of vacuum measurements and empirical data. Details and limitations of the IR measurement are discussed. Finally, the efficacy of methods for reducing thermal gradients in the microhotplate's active area is presented.

This paper presents an approach for treating uncertainty in the performance assessment process to efficiently address regulatory performance objectives for radioactive waste disposal and discusses the application of the approach at the Greater Confinement Disposal site. In this approach, the performance assessment methodology uses probabilistic risk assessment concepts to guide effective decisions about site characterization activities and provides a path toward reasonable assurance regarding regulatory compliance decisions. Although the approach is particularly amenable to requirements that are probabilistic in nature, the approach is also applicable to deterministic standards such as the dose-based and concentration-based requirements.

An oscillator technology using surface acoustic wave delay lines integrated with GaAs MESFET electronics has been developed for GaAs-based integrated microsensor applications. The oscillator consists of a two-port SAW delay line in a feedback loop with a four-stage GaAs MESFET amplifier. Oscillators with frequencies of 470, 350, and 200 MHz have been designed and fabricated. These oscillators are also promising for other RF applications.

XTX8003 is an extrudable explosive composed of 80% PETN and 20% Sylgard 182 (polydimethylsiloxane). Knowledge of the aging characteristics of XTX8003 is desired to understand the relationship between chemical and physical changes and performance. This understanding will allow improved assessment of the current state and also projected lifetime of components that contain this material. A literature search revealed few published studies of the aging behavior of XTX8003 or a chemically similar material, LX-13. Two studies showed that detonation velocity had decreased after storage at 70 C for two years. Another study showed a 30% decrease in target penetration by conical shaped charge after 12 weeks of storage at 82 C. Only one study was found which evaluated chemical and physical changes, but no information was available to correlate performance degradation to chemical and physical changes in the material. In summary, the major changes seen in aged XTX8003 are in detonation velocity and particle morphology, but particle morphology does not appear to be the determining factor in the loss of detonation velocity. The study will continue at least 24 months, at which time the data will be evaluated to determine how best to continue with the remaining test samples.

In a construction project, the contractor and the owner each have a responsibility for ensuring the health and safety of personnel on a project site. The contractor has the responsibility for ensuring that the provisions of OSHA'S safety and health regulations are followed and that the work is conducted in a safe and well thought out manner (Kohn 1996). The owner has a responsibility for disclosing to the contractor those owner-controlled hazards that are present in the work area due to ongoing and past operations (OSHA 1997). With the owner taking an active role in disclosing the potential hazards, the contractor is able to account for, plan, and mitigate potential health and safety issues during the performance phase of the project. At Sandia National Laboratories, this disclosure is made early in the project through the use of processes developed specifically for this purpose.

Lynx is a high resolution, synthetic aperture radar (SAR) that has been designed and built by Sandia National Laboratories in collaboration with General Atomics (GA). Although Lynx may be operated on a wide variety of manned and unmanned platforms, it is primarily intended to be fielded on unmanned aerial vehicles. In particular, it may be operated on the Predator, I-GNAT, or Prowler II platforms manufactured by GA Aeronautical Systems, Inc. The Lynx production weight is less than 120 lb. and has a slant range of 30 km (in 4 mm/hr rain). It has operator selectable resolution and is capable of 0.1 m resolution in spotlight mode and 0.3 m resolution in stripmap mode. In ground moving target indicator mode, the minimum detectable velocity is 6 knots with a minimum target cross-section of 10 dBsm. In coherent change detection mode, Lynx makes registered, complex image comparisons either of 0.1 m resolution (minimum) spotlight images or of 0.3 m resolution (minimum) strip images. The Lynx user interface features a view manager that allows it to pan and zoom like a video camera. Lynx was developed under corporate finding from GA and will be manufactured by GA for both military and commercial applications. The Lynx system architecture will be presented and some of its unique features will be described. Imagery at the finest resolutions in both spotlight and strip modes have been obtained and will also be presented.

A novel approach to simulating the dominant dynamic processes present during concentrated energy beam welding of metals is presented. A model for transient behavior of the front keyhole wall is developed. It is assumed that keyhole propagation is dominated by evaporation recoil-driven melt expulsion from the beam interaction zone. Results from the model show keyhole instabilities consistent with experimental observations of metal welding, metal cutting and ice welding.

We have been working for many years to develop improved methods for predicting the lifetimes of polymers exposed to air environments and have recently turned our attention to seal materials. This paper describes an extensive study on a butyl material using elevated temperature compression stress-relaxation (CSR) techniques in combination with conventional oven aging exposures. The results initially indicated important synergistic effects when mechanical strain is combined with oven aging, as well as complex, non-Arrhenius behavior of the CSR results. By combining modeling and experiments, we show that diffusion-limited oxidation (DLO) anomalies dominate traditional CSR experiments. A new CSR approach allows us to eliminate DLO effects and recover Arrhenius behavior. Furthermore, the resulting CSR activation energy (E{sub a}) from 125 C to 70 C is identical to the activation energies for the tensile elongation and for the oxygen consumption rate of unstrained material over similar temperature ranges. This strongly suggests that the same underlying oxidation reactions determine both the unstrained and strained degradation rates. We therefore utilize our ultrasensitive oxygen consumption rate approach down to 23 C to show that the CSR E{sub a} likely remains unchanged when extrapolated below 70 C, allowing very confident room temperature lifetime predictions for the butyl seal.

The relationships between the extent of interfacial bonding, energy dissipation mechanisms, and fracture toughness in a glassy adhesive/inorganic solid joint are not well understood. We address this subject with a model system involving an epoxy adhesive on a polished silicon wafer containing its native oxide. The extent of interfacial bonding, and the wetting behavior of the epoxy, is varied continuously using self-assembling monolayers (SAMs) of octadecyltrichlorosilane (ODTS). The epoxy interacts strongly with the bare silicon oxide surface, but forms only a very weak interface with the methylated tails of the ODTS monolayer. We examine the fracture behavior of such joints as a function of the coverage of ODTS in the napkin-ring geometry. Various characterization methods are applied to the ODTS-coated surface before application of the epoxy, and to both surfaces after fracture. The fracture data are discussed with respect to the wetting of the liquid epoxy on the ODTS-coated substrates, the locus of failure, and the energy dissipation mechanisms. Our goal is to understand how energy is dissipated during fracture as a function of interface strength.

The Waste Isolation Pilot Plant (WIPP) is a mined repository constructed by the US Department of Energy for the permanent disposal of transuranic wastes generated since 1970 by activities related to national defense. The WIPP is located 42 km east of Carlsbad, New Mexico, in bedded salt (primarily halite) of the Late Permian (approximately 255 million years old) Salado Formation 655 m below the land surface. Characterization of the site began in the mid-1970s. Construction of the underground disposal facilities began in the early 1980s, and the facility received final certification from the US Environmental Protection Agency in May 1998. Disposal operations are planned to begin following receipt of a final permit from the State of New Mexico and resolution of legal issues. Like other proposed geologic repositories for radioactive waste, the WIPP relies on a combination of engineered and natural barriers to isolate the waste from the biosphere. Engineered barriers at the WIPP, including the seals that will be emplaced in the access shafts when the facility is decommissioned, are discussed in the context of facility design elsewhere in this volume. Physical properties of the natural barriers that contribute to the isolation of radionuclides are discussed here in the context of the physiographic, geologic, and hydrogeologic setting of the site.

Two-well convergent-flow tracer tests conducted in the Culebra dolomite (Rustler Formation, New Mexico, USA) are analyzed with both single-and multiple-rate, double-porosity models. Parameter estimation is used to determine the mean and standard deviation of a Iog- normal distribution of diffision rate coefficients as well as the advective porosity and longitudinal dispersivity. At two different test sites, both mukirate and single-rate models are capable of accurately modeling the observed data. Estimated model parameters are tested against breakthrough curves obtained along the same transport pathway at a different pumping rate. Implications of the rnultirate mass-transfer model at time and length scales greater than those of the tracer tests include the instantaneous saturation of a fraction of the matrix ~d the possibility of a fraction of the matrix remaining unsaturated at long times.

A single-well injection-withdrawal (SWIW) test is evaluated as a tool to differentiate between single- and double-porosity conceptualizations of a system. Results from single-porosity simulations incorporating plume drift are also compared to observed data from a recent series of SWIW tests conducted in a fractured dolomite unit, for which a double-porosity conceptualization has been proposed. We evaluate the difficulty of differentiating the response for a double-porosity conceptualization from that for a heterogeneous, single-porosity conceptualization incorporating plume drift. Results of sensitivity studies on multiple, stochastically generated, heterogeneous transmissivity fields indicate that to simulate extremely slow mass-recovery rates for a SWIW test with a single-porosity conceptualization, the following conditions must be present: plume drift, extreme heterogeneities (high {sigma}InT), and an unusual configuration of the high and low transmissivity regions relative to the well location. A compilation of existing data suggests that the high degree of heterogeneity necessary is rare at the SWIW test scale.The observed data from the SWIW tracer tests cannot be matched to numerical simulation results when a single-porosity conceptualization is assumed. A signature of significant drift is less than 100% mass recovery with a zero derivative with respect to time of the late-time normalized cumulative mass curve indicating mass transported outside the capture zone of the withdrawal well. To minimize the risk of misinterpretation, an important design feature for SWIW tests is the collection of late-time data so that percent total mass recovery can be calculated.

Abstract not provided.

Traveltimes of head waves propagating within a three-dimensional (3D) multilayered earth are described by straightforward mathematical formulae. The earth model consists of a set of homogeneous and isotropic layers bounded by plane interfaces. Each interface (including the surface) may possess arbitrary strike and dip. In this model, the source-to-receiver raypath of a critically refracted wave consists of a set of straight line segments, not confined to a single plane. Algebraic derivations of the traveltime expressions are greatly simplified by using a novel 3D form of Snell's law of refraction. Various generalizations of the basic traveltime equation extend its applicability to arbitrary source-receiver recording geometries and/or mode-converted waves. Related expressions for the traveltimes of reflected waves and one-way transmitted waves propagating in the same layered earth model are obtained as byproducts of the analysis. The expressions contain a set of unit raypath orientation vectors that depend implicitly on source and receiver coordinates. Hence, the equations cannot be characterized as closed-form in the mathematical sense. However, for critically refracted waves, these vectors can be obtained by a minimal amount of numerical raytracing. The traveltime formulae are useful for a variety of forward modeling and inversion purposes.

The rapidly increasing use of composites on commercial airplanes coupled with the potential for economic savings associated with their use in aircraft structures means that the demand for composite materials technology will continue to increase. Inspecting these composite structures is a critical element in assuring their continued airworthiness. The FAA's Airworthiness Assurance NDI Validation Center, in conjunction with the Commercial Aircraft Composite Repair Committee (CACRC), is developing a set of composite reference standards to be used in NDT equipment calibration for accomplishment of damage assessment and post-repair inspection of all commercial aircraft composites. In this program, a series of NDI tests on a matrix of composite aircraft structures and prototype reference standards were completed in order to minimize the number of standards needed to carry out composite inspections on aircraft. Two tasks, related to composite laminates and non-metallic composite honeycomb configurations, were addressed. A suite of 64 honeycomb panels, representing the bounding conditions of honeycomb construction on aircraft, were inspected using a wide array of NDI techniques. An analysis of the resulting data determined the variables that play a key role in setting up NDT equipment. This has resulted in a prototype set of minimum honeycomb reference standards that include these key variables. A sequence of subsequent tests determined that this minimum honeycomb reference standard set is able to fully support inspections over the fill range of honeycomb construction scenarios. Current tasks are aimed at optimizing the methods used to engineer realistic flaws into the specimens. In the solid composite laminate arena, we have identified what appears to be an excellent candidate, G11 Phenolic, as a generic solid laminate reference standard material. Testing to date has determined matches in key velocity and acoustic impedance properties, as well as, low attenuation relative to carbon laminates. Furthermore, comparisons of resonance testing response curves from the G11 Phenolic prototype standard was very similar to the resonance response curves measured on the existing carbon and fiberglass laminates. NDI data shows that this material should work for both pulse-echo (velocity-based) and resonance (acoustic impedance-based) inspections. Additional testing and industry review activities are underway to complete the validation of this material.

The usual divisions of science and technology into pure research applied research, development, demonstration, and production creates impediments for moving knowledge into socially useful products and services. This failing has been previously discussed without concrete suggestions of how to improve the situation. In the proposed framework the divisive and artificial distinctions of basic and applied are softened, and the complementary and somewhat overlapping roles of universities, corporations, and federal labs are clarified to enable robust partnerships. As a collegial group of scientists and technologists from industry, university, and government agencies and their national laboratories, we have worked together to clarify this framework. We offer the results in hopes of improving the results from investments in science and technology and thereby helping strengthen the social contract between the public and private investors and the scientists-technologists.

We have designed and fabricated a system using micromachining technologies that represents the first phase of an effort to develop a miniaturized or micro trajectory safety subsystem. Two Surface Micromachined (SMM) devices have been fabricated. The first is a device, denoted the Shuttle Mechanism, that contains a suspended shuttle that has a unique code imbedded in its surface. The second is a mechanical locking mechanism, denoted a Stronglink, that uses the code imbedded in the Shuttle Mechanism for unlocking. The Stronglink is designed to block a beam of optical energy until unlocked. A Photonic Integrated Circuit (PIC) fabricated in Gallium Arsenide (GaAs) and an ASIC have been designed to read the code contained in the Shuttle Mechanism. The ASIC interprets the data read by the PIC and outputs low-level drive signals for the actuators used by the Stronglink. An off-chip circuit amplifies the drive signals. Once the Stronglink is unlocked, a laser array that is assembled beneath the device is energized and light is transmitted through an aperture.

In this paper, a prototype robotic workcell for the parallel assembly of LIGA components is described. A Cartesian robot is used to press 386 and 485 micron diameter pins into a LIGA substrate and then place a 3-inch diameter wafer with LIGA gears onto the pins. Upward and downward looking microscopes are used to locate holes in the LIGA substrate, pins to be pressed in the holes, and gears to be placed on the pins. This vision system can locate parts within 3 microns, while the Cartesian manipulator can place the parts within 0.4 microns.

Recently, a model based on geographic information system (GIS) processing of US Census Block data has made high-resolution population analysis for transportation risk analysis technically and economically feasible. Population density bordering each kilometer of a route may be tabulated with specific route sections falling into each of three categories (Rural, Suburban or Urban) identified for separate risk analysis. In addition to the improvement in resolution of Urban areas along a route, the model provides a statistically-based correction to population densities in Rural and Suburban areas where Census Block dimensions may greatly exceed the 800-meter scale of interest. A semi-automated application of the GIS model to a subset of routes in Nevada (related to the Yucca Mountain project) are presented, and the results compared to previous models including a model based on published Census and other data. These comparisons demonstrate that meaningful improvement in accuracy and specificity of transportation risk analyses is dependent on correspondingly accurate and geographically-specific population density data.

Deep level defects in MOCVD-grown, unintentionally doped p-type InGaAsN films lattice matched to GaAs were investigated using deep level transient spectroscopy (DLTS) measurements. As-grown p-InGaAsN showed broad DLTS spectra suggesting that there exists a broad distribution of defect states within the band-gap. Moreover, the trap densities exceeded 10{sup 15} cm{sup {minus}3}. Cross sectional transmission electron microscopy (TEM) measurements showed no evidence for threading dislocations within the TEM resolution limit of 10{sup 7} cm{sup {minus}2}. A set of samples was annealed after growth for 1800 seconds at 650 C to investigate the thermal stability of the traps. The DLTS spectra of the annealed samples simplified considerably, revealing three distinct hole trap levels with energy levels of 0.10 eV, 0.23 eV, and 0.48 eV above the valence band edge with trap concentrations of 3.5 x 10{sup 14} cm{sup {minus}3}, 3.8 x 10{sup 14} cm {sup {minus}3}, and 8.2 x 10{sup 14} cm{sup {minus}3}, respectively. Comparison of as-grown and annealed DLTS spectra showed that post-growth annealing effectively reduced the total trap concentration by an order of magnitude across the bandgap. However, the concentration of a trap with an energy level of 0.48 eV was not affected by annealing indicating a higher thermal stability for this trap as compared with the overall distribution of shallow and deep traps.