Publications

Nuclear reactor-pumped lasers (RPLs) have been developed in the US by the Department of Energy for over two decades, with the primary research occurring at Sandia National Laboratories and Idaho National Engineering Laboratory. The US program has experimentally demonstrated reactor-pumped lasing in various mixtures of xenon, argon, neon, and helium at wavelengths of 585, 703, 725, 1,271, 1,733, 1,792, 2,032, 2,630, 2,650, and 3,370 nm with intrinsic efficiency as high as 2.5%. The major strengths of a reactor-pumped laser are continuous high-power operation, modular construction, self-contained power, compact size, and a variety of wavelengths (from visible to infrared). These characteristics suggest numerous applications not easily accessible to other laser types. The continuous high power of an RPL opens many potential manufacturing applications such as deep-penetration welding and cutting of thick structures, wide-area hardening of metal surfaces by heat treatment or cladding application, wide-area vapor deposition of ceramics onto metal surfaces, production of sub-micron sized particles for manufacturing of ceramics, and 3-D ceramic lithography. In addition, a ground-based RPL could beam its power to space for such activities as illuminating geosynchronous communication satellites in the earth`s shadow to extend their lives, beaming power to orbital transfer vehicles, removing space debris, and providing power (from earth) to a lunar base during the long lunar night.

Investigations are being performed on a high current (16 kA), mildly relativistic (400kV), L-band klystron source. Experiments are in an early stage, and thus far have progressed to beam modulation studies. This paper discusses general klystron design considerations, beam propagation results, initial modulation results, and various extraction techniques being considered.

Calculational results are presented here for a class of intermediate-velocity penetration problems. The problems of interest involve penetration of moderate-strength target materials by high-strength projectiles. Two series of metal penetration experiments and a series of concrete slab perforation tests were simulated in this study. The computer code used for the calculations was the CTH code, which employs a recently-developed ``boundary layer`` algorithm for treating penetration problems such as these.

This report presents an application of probabilistic models and risk based criteria for determining the risk impact of the Limiting Conditions of Operations (LCOs) in the Technical Specifications (TSs) of a boiling water reactor during shutdown. This analysis studied the risk impact of the current requirements of Allowed Outage Times (AOTs) and Surveillance Test Intervals (STIs) in eight Plant Operational States (POSs) which encompass power operations, shutdown, and refueling. This report also discusses insights concerning TS action statements.

Becoming aware of the significant changes of the past several years and their effect on the expectations to international safeguards, it is necessary to reflect on which direction the development of nuclear safeguards in a new era needs to take. The time-proven monitoring techniques, based on quantitative factors and demonstrated universal application, have shown their merit. However, the new expectations suggest a possibility that a future IAEA safeguards, system could rely more heavily on the value of a comprehensive, transparent, and open implementation regime. Within such a regime, the associated measures need to be determined and technological support identified. This paper will identify proven techniques which, with appropriate implementation support, could most quickly make available additional measures for a comprehensive, transparent and open implementation regime. In particular, it will examine the future of remote monitoring in International Safeguards, and provide an update on the International Remote Monitoring Project and related implications.

This paper presents an overview of the Nuclear Electric Propulsion Space Test Program (NEPSTP). The program goals, the proposed mission, the spacecraft, and the Topaz II space nuclear power system are described. The subject of flight qualification is examined and the inherent difficulties of qualifying a space reactor are described. The differences between US and Russian flight qualification procedures are explored. A plan is then described that was developed to determine an appropriate flight qualification program for the Topaz II reactor to support a possible NEPSTP launch. Refocusing of the activities of the Ballistic Missile Defense Organization (BMDO), combined with budgetary pressures, forced the cancellation of the NEPSTP at the end of the 1993 fiscal year.

Thin film decoupling capacitors consisting of submicron thick, sol-gel Pb(Zr,Ti)O{sub 3} layers between Pt electrodes on a Si substrate have recently been developed. Because the capacitor structure needs to be only {approximately}3 {mu}m thick, these devices offer advantages such as decreased package volume and ability to integrate so that interconnect inductance is decreased, which allows faster IC processing rates. To fully utilize these devices, techniques of integrating them onto packages such as multi-chip modules and printed wiring boards or onto IC dies must be developed. The results of our efforts at developing integration processes for these capacitors are described here. Specifically, we have demonstrated a process for printing solder on the devices at the Si wafer level and reflowing it to form bumps and have developed a process for fabricating the devices on thin (25 to 75 {mu}m) substrates to facilitate integration onto ICs and printed wiring boards. Finally, we assessed the feasibility of fabricating the devices on rough surfaces to determine whether it would be possible to fabricate these capacitors directly on multi-layer ceramic substrates.

In this paper, I review the significant issues and the development of solar concentrators and thermal receivers for central-receiver power plants and dish/engine systems. Due to the breadth of the topic area, I have arbitrarily narrowed the content of this paper by choosing not to discuss line-focus (trough) systems and energy storage. I will focus my discussion on the development of heliostats, dishes, and receivers since the 1970s with an emphasis on describing the technologies and their evolution, identifying some key observations and lessons learned, and suggesting what the future in component development may be.

A new class of inorganic ion exchangers, called crystalline silicotitanates (CSTs), has been prepared at Sandia National Laboratories and Texas A&M University. CSTs have been determined to have high selectivity for the adsorption of Cs and Sr, and several other radionuclides from highly alkaline, high-sodium supernate solutions such as those found at Westinghouse Hanford (WHC). Continuous flow, ion-exchange columns are expected to be used to remove Cs and other radionuclides from the Hanford tank supernate. The proposed application for the CST would be Cs removal from highly alkaline salt solutions in a single pass process with interim storage of the Cs loaded CST until the glass vitrification plant is operational. This paper presents test results which address material requirements relevant for Hanford radwaste processing. This paper also discusses the integrated experimental and modeling approach being developed to establish the performance of the CST materials for the range of solution compositions and processing conditions which are expected to occur. The status on the commercialization of the CST material is also discussed.

Grid partitioning is the method of choice for decomposing a wide variety of computational problems into naturally parallel pieces. In problems where computational load on the grid or the grid itself changes as the simulation progresses, the ability to repartition dynamically and in parallel is attractive for achieving higher performance. We describe three algorithms suitable for parallel dynamic load-balancing which attempt to partition unstructured grids so that computational load is balanced and communication is minimized. The execution time of algorithms and the quality of the partitions they generate are compared to results from serial partitioners for two large grids. The integration of the algorithms into a parallel particle simulation is also briefly discussed.

This paper describes and evaluates operational experiences with the Accident Response Mobile Manipulation System (ARMMS) during simulated accident site salvage operations which might involve nuclear weapons. The ARMMS is based upon a teleoperated mobility platform with two Schilling Titan 7F Manipulators.

The cost of most photovoltaic (PV) systems is more a function of the balance of system (BOS) components than the collectors. The exception to this rule is the grid-tied system whose cost is related more directly to the collectors, and secondarily to the inverter/controls. In fact, recent procurements throughout the country document that collector costs for roof-mounted, utility-tied systems (Russell, PV Systems Workshop, 7/94) represent 60% to 70% of the system cost. This contrasts with the current market for packaged stand-alone all PV or PV-hybrid systems where collectors represent only 25% to 35% of the total. Not only are the BOS components the cost drivers in the current cost-effective PV system market place, they are also the least reliable components. This paper discusses the impact that BOS issues have on component performance, system performance, and system cost and reliability. We will also look at recent recommended changes in system design based upon performance evaluations of fielded PV systems.

The U.S. Department of Energy (DOE) has supported the development of solar thermal electric (STE) technology since the early 1970s. From its inception, the program has held a long-term goal of nurturing STE technologies from the research and development (R&D) stage through technology development, ultimately leading to commercialization. Within the last few years, the focus of this work -has shifted from R&D to cost-shared cooperative projects with industry. These projects are targeted not just at component development, but at complete systems, marketing approaches, and commercialization plans. This changing emphasis has brought new industry into the program and is significantly accelerating solar thermal`s entry into the marketplace. Projects such as Solar Two in the power tower area, a number of dish/Stirling joint ventures in the modular power area, and operations and maintenance (O&M) cost reduction studies will be discussed as examples of this new focus.

Sandia National Laboratories has designed, constructed and operated bare metal Godiva-type and pool-type pulse reactors since 1961. The reactor facilities were designed to support a wide spectrum of research, development, and testing activities associated with weapon and reactor systems.

Hazardous operations which have in the past been completed by technicians are under increased scrutiny due to high costs and low productivity associated with providing protective clothing and environments. As a result, remote systems are needed to accomplish many hazardous materials handling tasks such as the clean-up of waste sites in which the exposure of personnel to radiation, chemical, explosive and other hazardous constituents is unacceptable. Computer models augmented by sensing, and structured, modular computing environments are proving effective in automating many unstructured hazardous tasks. Work at Sandia National Laboratories (SNL) has focused on applying flexible automation (robotics) to meet the needs of the U.S. Department of Energy (USDOE). Dismantling facilities, environmental remediation, and materials handling in changing, hazardous environments lead to many technical challenges. Computer planning, monitoring and operator assistance shorten training cycles, reduce errors, and speed execution of operations. Robotic systems that re-use well-understood generic technologies can be much better characterized than robotic systems developed for a particular application, leading to a more reliable and safer systems. Further safety in robotic operations results from use of environmental sensors and knowledge of the task and environment. Collision detection and avoidance is achieved from such sensor integration and model-based control. This paper discusses selected technologies developed at SNL for use within the USDOE complex that have been or are ready for transfer to government and industrial suppliers. These technologies include sensors, sub-systems, and the design philosophy applied to quickly integrate them into a working robotic system. This paper represents the work of many people at the Intelligent Systems and Robotics Center at SNL, to whom the credit belongs.

The Hypervelocity Experimental Research Database (HERD) described in this paper was developed to aid researchers with code validation for impacts that occur at velocities faster than the testable regime. Codes of concern include both hydrocodes and fast-running analytical or semi-empirical models used to predict the impact phenomenology and damage that results to projectiles and targets. There are several well documented experimental programs that can serve as benchmarks for code validation; these are identified and described. Recommendations for further experimentation (a canonical problem) to provide validation data are also discussed.

Radar imaging and detection of objects buried in soil has potentially important applications in the areas of nonproliferation of weapons, environmental monitoring, hazardous-waste site location and assessment, and even archeology. In order to understand and exploit this potential, it is first necessary to understand how the soil responds to an electromagnetic wave, and how targets buried within the soil scatter the electromagnetic wave. We examine the response of the soil to a short pulse, and illustrate the roll of the complex dielectric permittivity of the soil in determining radar range resolution. This leads to a concept of an optimum frequency and bandwidth for imaging in a particular soil. We then propose a new definition for radar cross section which is consistent with the modified radar equation for use with buried targets. This radar cross section plays the same roll in the modified radar equation as the traditional radar cross section does in the free-space radar equation, and is directly comparable to it. The radar cross section of several canonical objects in lossy media is derived, and examples are given for several object/soil combinations.

The National Solar Thermal Test Facility (NSTTF) at Sandia National Laboratories in Albuquerque, New Mexico, USA conducts testing of solar thermal components and systems, funded primarily by the US Department of Energy. Activities are conducted in support of Central Receiver Technology, Distributed Receiver Technology and Design Assistance projects. All activities are performed in support of various cost-shared government/industry joint ventures and, on a design assistance basis, in support of a number of other industry partners.

The U.S. Department of Energy (DOE) and the Electric Power Research Institute (EPRI), in cooperation with nuclear power plant utilities and the Nuclear Energy Institute, have prepared equipment aging evaluations of nuclear power plant equipment for life extension considerations. Specifically, these evaluations focused on equipment considered important for plant license renewal (U.S. Code of Federal Regulations 10CFR54). {open_quotes}Industry Reports{close_quotes} (IRs), jointly funded by DOE and EPRI, evaluated the aging of major systems, structures, and components (e.g., reactor pressure vessels, Class I structures, PWR and BWR containments, etc.) and contain a mixture of technical and licensing information. {open_quotes}Aging Management Guidelines{close_quotes} (AMGs), funded by DOE, evaluate aging for commodity types of equipment (e.g., pumps, electrical switchgear, heat exchangers, etc.) and concentrate on technical issues only. AMGs are intended for systems engineers and plant maintenance staff. A significant number of technical issues were resolved during IR interactions with the U.S. Nuclear Regulatory Commission (NRC). However, certain technical issues have not been resolved and are considered {open_quotes}open{close_quotes}. Examples include certain issues related to fatigue, neutron irradiation embrittlement, intergranular stress corrosion cracking (IGSCC) and electrical cable equipment qualification. Direct NRC interaction did not take place during preparation of individual AMGs due to their purely technical nature. The eventual use of AMGs in a future license renewal application will likely require NRC interaction at that time. With a few noted exceptions, the AMG process indicated that current aging management practices of U.S. utilities were effective in preventing age-related degradation. This paper briefly describes the IR and AMG processes and summarizes the unresolved technical issues identified through preparation of the documents.

The role of force measurements in vibration testing is discussed. The rational for a vibration test based on the extremal control of force and acceleration is developed. The differences between force measurements in vibration testing and modal testing is discussed. Several methods for estimating the input force in a vibration test are outlined.

A dynamic simulator of the TOPAZ II reactor system has been developed for the Nuclear Electric Propulsion Space Test Program. The simulator is a self-contained IBM-PC compatible based system that executes at a speed faster than real-time. The simulator combines first-principle modeling and empirical correlations in its algorithm to attain the modeling accuracy and computational through-put that are required for real-time execution. The overall execution time of the simulator for each time step is 15 ms when no data is written to the disk, and 18 ms when nine double precision data points are written to the disk once in every time step. The simulation program has been tested and it is able to handle a step decrease of $8 worth of reactivity. It also provides simulation of fuel, emitter, collector, stainless steel, and ZrH moderator failures. Presented in this paper are the models used in the calculations, a sample simulation session, and a discussion of the performance and limitations of the simulator. The simulator has been found to provide realistic real-time dynamic response of the TOPAZ II reactor system under both normal and causality conditions.

This is the final report of a program to develop a commercial, high-efficiency, low-cost concentrator solar cell compatible with Spectrolab`s existing manufacturing infrastructure for space solar cells. The period covered is between 1991 and 1993. The program was funded through Sandia National Laboratories through the DOE concentrator initiative and, was also cost shared by Spectrolab. As a result of this program, Spectrolab implemented solar cells achieving an efficiency of over 19% at 200 to 300X concentration. The cells are compatible with DOE guidelines for a cell price necessary to achieve a cost of electricity of 12 cents a kilowatthour.

The theoretical and numerical background for the finite element computer program, COYOTE II, is presented in detail. COYOTE II is designed for the multi-dimensional analysis of nonlinear heat conduction problems and other types of diffusion problems. A general description of the boundary value problems treated by the program is presented. The finite element formulation and the associated numerical methods used in COYOTE II are also outlined. Instructions for use of the code are documented in SAND94-1179; examples of problems analyzed with the code are provided in SAND94-1180.

Four commercial exterior fiber optic intrusion detection sensors installed in a gravel test bed have been evaluated. These are the FOIDS models 1000 and 500, Sabreline, and Fiber SenSys model M106E. In addition, FOIDS models 1000 and 500 installed on a fence were evaluated. The data was obtained from a perimeter sensor test field in Albuquerque.

User instructions are given for the finite element computer program, COYOTE II. COYOTE II is designed for the multi-dimensional analysis of nonlinear heat conduction problems including the effects of enclosure radiation and chemical reaction. The theoretical background and numerical methods used in the program are documented in SAND94-1173. Examples of the use of the code are presented in SAND94-1180.

This study identifies technologies required to extend the capabilities of airborne light detection and ranging (lidar) systems and establish the feasibility of autonomous space-based lidars. Work focused on technologies that enable the development of a lightweight, low power, rugged and autonomous Differential Absorption Lidar (DIAL) instruments. Applications for airborne or space-based DIAL include the measurement of water vapor profiles in support of climate research and processing-plant emissions signatures for environmental and nonproliferation monitoring. A computer-based lidar performance model was developed to allow trade studies to be performed on various technologies and system configurations. It combines input from the physics (absorption line strengths and locations) of the problem, the system requirements (weight, power, volume, accuracy), and the critical technologies available (detectors, lasers, filters) to produce the best conceptual design. Conceptual designs for an airborne and space-based water vapor DIAL, and a detailed design of a ground-based water vapor DIAL demonstration system were completed. Future work planned includes the final testing, integration, and operation of the demonstration system to prove the capability of the critical enabling technologies identified.

The shock-loading of natural materials by an impact or explosion can result in the formation of modified and altered phases. In order to characterize the resulting material and to evaluate the extent of shock modification, the authors have used nuclear magnetic resonance (NMR) spectroscopy to examine several experimentally shocked minerals. In three related NMR studies, they have (1) examined shocked clinoptilolite, (2) performed a preliminary analysis of shocked quartz, and (3) reproduced shocked quartz results with detailed spectral deconvolutions, and extended it with NMR analysis of shocked feldspar powders.

During July-September, 1993, Sandia National Laboratories, in cooperation with Far West Capital, drilled a 4000 feet exploratory slimhole (3.9 inch diameter) in the Steamboat Hills geothermal field near Reno, Nevada. This well was part of Sandia`s program to evaluate slimholes as a geothermal exploration tool. During and after drilling the authors performed four series of production and injection tests while taking downhole (pressure-temperature-spinner) and surface (wellhead pressure and temperature, flow rate) data. In addition to these measurements, the well`s data set includes: continuous core (with detailed log); borehole televiewer images of the wellbore`s upper 500 feet; daily drilling reports from Sandia and from drilling contractor personnel; daily drilling fluid record; numerous temperature logs; and comparative data from production and injection wells in the same field. This report contains: (1) a narrative account of the drilling and testing, (2) a description of equipment used, (3) a brief geologic description of the formation drilled, (4) a summary and preliminary interpretation of the data, and (5) recommendations for future work.

This report documents the characterization of thin copper films grown at Sandia as part of on-going research in copper CVD involving Sandia and Schumacher, Inc. The films have been grown using the copper (1) CVD precursor (hfac)Cu(TMVS), which was first developed by Schumacher and has been supplied to Sandia by that company. The CVD was performed using a novel technique in which direct liquid coinjection of (hfac)Cu(TMVS) and TMVS (trimethylvinylsilane) into a commercial reactor is utilized. Films were deposited onto silicon nitride substrates at temperatures in the range of 220-250{degrees}C, with growth rates in the range of 400-800 {angstrom}/min. These films have been analyzed by a variety of techniques, with an emphasis on factors that may influence the resistivity, including thickness, purity, density, grain size, and stress. The authors show that these films have as-deposited resistivities of 1.86 {+-} 0.1 {mu}{Omega}-cm, or 1.82 {+-} 0.1 {mu}{Omega}-cm after accounting for surface scattering effects. The latter value is only 0.14 {mu}{Omega}-cm above the value for high purity bulk copper. The authors discuss factors that may account for this residual resistivity. They also discuss the effects of film surface roughness on film thickness and resistivity measurements, noting some potential problems associated with the commonly used surface profilometry technique. These results help to establish (hfac)Cu(TMVS) as one of the most promising available copper CVD precursors for metallization applications.

A Zinc/Air Battery Review and Strategic Planning Meeting was held in 1993. One outcome of the meeting was recognition of the need for a report on the current status of the technology. This report contains contributions from many of the attendees at the above meeting and expresses their views on where the technology is today and what could/should be done to improve its performance.

As the product requirements are defined, business processes and procedures should be redeveloped in order to fully realize the benefits of the product. Process Quality Management Improvement (PQMI) can be used as a methodology to redevelop business processes and procedures for an organization. Business processes and procedures are an integral part of the Product Realization Process (PRP). This document focuses on the development of business processes and procedures. The business processes and procedures should be developed concurrently with the product. This enables the product and project as a whole to be transitioned smoothly and successfully. Without business processes and procedures to back up the changes brought with the new product, the product will not be used to its full potential and the transition will not be as smooth. Developing business processes and procedures lends itself to the PQMI methodology because PQMI calls for all the information needed to develop business processes and procedures and ensures the business processes and procedures are developed in a quality manner. The PQMI steps are: (1) Establishing process management responsibilities; (2) Defining Processes and Identifying Customer Requirements; (3) Defining and Establishing Measures; (4) Assessing Conformance to Customer Requirements; (5) Investigating Processes to Identify Improvement Opportunities; (6) Ranking Improvement Opportunities and Setting Objectives; and (7) Improving Process Quality. The successful implementation of a product can be attributed to the standardization of business processes and procedures. These business processes and procedures describe in detail the day to day operations of a project. The development of business processes and procedures provide and environment for agile product realization.

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A specially designed ultrahigh vacuum in situ surface analysis and wetting system has been constructed to study the spreading of liquid metal solders on carefully prepared and well-characterized solid substrates. Initial studies have been completed for the spreading of pure tin solder on copper substrates in the absence of any fluxing agent. Surface chemical analysis by x-ray photoelectron spectroscopy showed the air-exposed surface to consisted of about 3 nm of Cu{sub 2}O, while the as-received surface consisted of about 8 nm of Cu{sub 2}O. The sputter-cleaned surface contained less than one monolayer (0.3 nm) of Cu{sub 2}O. Sample surfaces were prepared and spreading experiments performed without intermediate exposure of the surfaces to contaminating atmospheres. Solder spreading was performed under 50 torr of highly purified helium gas to allow for adequate thermal coupling between the solder and the substrate. Spreading experiments utilizing a linear temperature ramp show that pure tin solder spreads readily on oxidized copper surfaces at elevated temperatures. The initiation temperature for rapid tin spreading on the as-received copper surface was 325{degrees}C, similar to the temperature where isothermal spreading changes activation energy or rate. Decreasing the thickness of the oxide on the surface lowered the observed temperature for the initiation of spreading and increased the rate of spreading. On the sputter-cleaned copper surface, rapid solder spreading was observed immediately upon melting of the solder.

Sandia recently completed an updated strategic plan, the essence of which is presented in chapter 4. Sandia`s Strategic Plan 1994 takes its direction from DOE`s Fueling a Competitive Economy: Strategic Plan and provides tangible guidance for Sandia`s programs and operations. Although it is impossible to foresee precisely what activities Sandia will pursue many years from now, the strategic plan makes one point clear: the application of our scientific and engineering skills to the stewardship of the nation`s nuclear deterrent will be central to our service to the nation. We will provide the necessary institutional memory and continuity, experience base, and technical expertise to ensure the continued safety, security, and reliability of the nuclear weapons stockpile. As a multiprogram laboratory, Sandia will also continue to focus maximum effort on a broad spectrum of other topics consistent with DOE`s enduring core mission responsibilities: Defense (related to nuclear weapons), Energy, Environment (related to waste management and environmental remediation), and Basic Science.

The Department of Energy Order 5500.3A requires facility-specific hazards assessments be prepared, maintained, and used for emergency planning purposes. This hazards assessment document describes the chemical and radiological hazards associated with the Sandia Lightning Simulation Facility, Building 888. The entire inventory was screened according to the potential airborne impact to onsite and offsite individuals. The air dispersion model, ALOHA, estimated pollutant concentrations downwind from the source of a release, taking into consideration the toxicological and physical characteristics of the release site, the atmospheric conditions, and the circumstances of the release. The greatest distance at which a postulated facility event will produce consequences exceeding the Early Severe Health Effects threshold is 23 meters. The highest emergency classification is a Site Area Emergency. The Emergency Planning Zone is 65 meters.

The Yucca Mountain Project, managed by the U.S. Department of Energy, is examining the feasibility of siting a repository for high-level nuclear waste at Yucca Mountain on and adjacent to the Nevada Test Site. As part of the site characterization, a series of in situ thermomechanical experiments are planned, which are to be conducted in the Exploratory Studies Facility (ESF). In this report, the results of preliminary analyses of three of the in situ thermomechanical experiments are presented. The major objective of these analyses was to determine the boundaries of the thermally perturbed zones surrounding each of the experiments. The boundaries of the thermal zones needs to be known in order to avoid test interference between the experiments planned for the ESF. A second objective of these analyses was to calculate the displacements and stresses associated with the experiments, in order to advance the planning of the experiments.

A gridless technique called smooth particle hydrodynamics (SPH) has been coupled with the transient dynamics finite element code pronto. In this paper, a new weighted residual derivation for the SPH method will be presented, and the methods used to embed SPH within pronto will be outlined. Example SPH pronto calculations will also be presented. One major difficulty associated with the Lagrangian finite element method is modeling materials with no shear strength; for example, gases, fluids and explosive biproducts. Typically, these materials can be modeled for only a short time with a Lagrangian finite element code. Large distortions cause tangling of the mesh, which will eventually lead to numerical difficulties, such as negative element area or "bow tie" elements. Remeshing will allow the problem to continue for a short while, but the large distortions can prevent a complete analysis. SPH is a gridless Lagrangian technique. Requiring no mesh, SPH has the potential to model material fracture, large shear flows and penetration. SPH computes the strain rate and the stress divergence based on the nearest neighbors of a particle, which are determined using an efficient particle-sorting technique. Embedding the SPH method within pronto allows part of the problem to be modeled with quadrilateral finite elements, while other parts are modeled with the gridless SPH method. SPH elements are coupled to the quadrilateral elements through a contact-like algorithm. © 1994.

EXODUS II is a model developed to store and retrieve data for finite element analyses. It is used for preprocessing (problem definition), postprocessing (results visualization), as well as code to code data transfer. An EXODUS II data file is a random access, machine independent, binary file that is written and read via C, C++, or Fortran library routines which comprise the Application Programming Interface (API).

The CuPt-type ordering and dopant effects of In{sub 0.5}Ga{sub 0.5}P/GaAs epitaxial layers have been studied using spectroscopic ellipsometry and transmission electron microscopy. The degree of ordering was estimated by both transmission electron diffraction and direct band edge, E{sub 0}. Conventional lineshape fitting of E{sub 1}, E{sub 1}+{Delta}{sub 1}, and E{sub 2} gaps using the second derivative of pseudo dielectric functions shows that the peak position and oscillator strength of the E{sub 1} gap are basically a function of CuPt-type ordering whereas their broadening and phase depend mainly on carrier concentration. The decrease of E{sub 1} gap is explained in terms of CuPt-type ordering. In contrast to the E{sub 1} gap, all the lineshape parameters of the E{sub 2} gap depend mainly on CuPt-type ordering. This difference is discussed in terms of apparent {open_quotes}CuAu-type ordering{close_quotes} or Y2 structure which was observed by transmission electron diffraction.

A new die-level packaging technology, mBGA, is reported in this paper. The mBGA enables high circuit packaging density on multichip module (MCM), facilitates die testing to obtain ``known good die,`` and allows a cost effective module assembly. We have designed and fabricated a test vehicle to evaluate mBGA multichip module technology. This paper describes the mBGA technology and the test vehicle multichip module and reports preliminary results on the die test and burn-in, thermal performance and reliability studies.

The IC test industry has struggled for more than 30 years to establish a test approach that would guarantee a low defect level to the customer. We propose a comprehensive strategy for testing CMOS ICs that uses defect classes based on measured defect electrical properties. Defect classes differ from traditional fault models. Our defect class approach requires that the test strategy match the defect electrical properties, while fault models require that IC defects match the fault definition. We use data from Sandia Labs failure analysis and test facilities and from public literature. We describe test pattern requirements for each defect class and propose a test paradigm.

Several experimental melts were conducted using a moving mold electroslag remelting furnace. The conditions of electrode immersion depth, slag cap thickness, and melt current were varied. Mold wall temperatures and slag pool temperatures were measured and the heat flux through the mold wall was calculated. The relationships between varying ESR melt parameters and the resultant thermal conditions were examined. The thermal profile of the mold, the heat transfer to the mold coolant total and fractional, and the formation of a slag skin were studied.

There currently exists a critical need for tools to enhance the industrial competitiveness and agility of US industries involved in deformation processing of structural alloys. In response to this need, Sandia National Laboratories has embarked upon the QuikForm Initiative. The goal of this program is the development of computer-based tools to facilitate the design of deformation processing operations. The authors are currently focusing their efforts on the definition/development of a comprehensive system for the design of sheet metal stamping operations. The overall structure of the proposed QuikForm system is presented, and the focus of their thrust in each technical area is discussed.

The authors are working to understand why predictions of degradation behaviors and rates, based on accelerated thermal aging experiments, often fail to match with aging of polymers under service conditions. A main goal of these studies is to develop more reliable lifetime prediction methodologies.

Hydrous Metal Oxides (HMOs) are chemically synthesized materials which contain a homogeneous distribution of ion exchangeable alkali cations that provide charge compensation to the metal-oxygen framework. Both the presence of these alkali cations and the resulting high cation exchange capacities (4-5 meq/g) clearly set these HMO materials apart from conventional precipitated hydrous oxides. For catalyst applications, the HMO material serves as an ion exchangeable support which facilitates the uniform incorporation of catalyst precursor species. Following catalyst precursor incorporation, an activation step is required to convert the catalyst precursor to the desired active phase. Considerable process development activities at Sandia National Laboratories related to HMO materials have resulted in bulk silica-doped hydrous titanium oxide (HTO:Si)-supported NiMo catalysts that are more active in model compound reactions than commercial NiMo catalysts. These reactions, e.g. pyrene hydrogenation, simulate direct coal liquefaction. However, extension of this process to produce NiMo/HTO:Si catalyst coatings on commercial supports is of interest for liquefaction applications since overall catalyst cost can be reduced and bulk HTO:Si mechanical limitations can be circumvented. In the present effort, NiMo/HTO:Si has been evaluated for hydrodesulfurization (HDS) and hydrodenitrogenation (HDN) of coal derived liquids. NiMo/HTO:Si catalysts have been evaluated in both bulk (unsupported) form and a supported form on commercial alumina extrudates.

Degradation in nMOS transistors from gate oxide shorts is dependent upon oxide trapping and interface state generation. Three distinct damage mechanisms were identified, including generation of: (1) electron traps in the bulk oxide by the injected holes, N{sub ox,h}, (2) electron traps in the bulk oxide by the injected electrons, N{sub ox,e}, and (3) interface states, N{sub ss}. The three damage mechanisms are incorporated into a device lifetime prediction method.

Procedures for trajectory planning and control of flexible link robots are becoming increasingly important to satisfy performance requirements of hazardous waste removal efforts. It has been shown that utilizing link flexibility in designing open loop joint commands can result in improved performance as opposed to damping vibration throughout a trajectory. The efficient use of link compliance is exploited in this work. Specifically, experimental verification of minimum time, straight line tracking using a two-link planar flexible robot is presented. A numerical optimization process, using an experimentally verified modal model, is used for obtaining minimum time joint torque and angle histories. The optimal joint states are used as commands to the proportional-derivative servo actuated joints. These commands are precompensated for the nonnegligible joint servo actuator dynamics. Using the precompensated joint commands, the optimal joint angles are tracked with such fidelity that the tip tracking error is less than 2.5 cm.

Technologies for the demilitarization and disposal of conventional munitions and energetic materials are presented. A hazard separation system has been developed to remove hazardous subcomponents before processing. Electronic component materials separation processes have been developed that provide for demilitarization as well as the efficient recycling of materials. Energetic materials demilitarization and disposal using plasma arc and molten metal technologies are currently being investigated. These regulatory compliant technologies will allow the recycling of materials and will also provide a waste form suitable for final disposal.