Publications

A new viscoplastic theory for CusilABA and other braze alloys has been developed. Like previous viscoplastic theories,this new theory uses a hyperbolic sine function of effective stress in its kinetic equation for the inelastic strain rate. This new theory has an internal state variable which accounts for isotropic hardening and recovery and a second-order, internal state tensor which accounts for kinematic hardening and recovery. Unlike previous theories, the new theory uses evolution equations for the state variables which describe competing mechanisms of power law hardening and static recovery. The evolution equations used in previous theories describe competing mechanisms of linear hardening, dynamic and static recovery. The new viscoplastic theory was implemented in several finite element codes and used in several metal-to-ceramic brazing simulations. Two approaches for obtaining material parameters for the new viscoplastic theory were developed.

A simplified surface reaction mechanism is presented for the CVD of diamond thin films. The mechanism also accounts for formation of point defects in the diamond lattice, an alternate, undesirable reaction pathway. Both methyl radicals and atomic C are considered as growth precursors. While not rigorous in all details, the mechanism is useful in describing the CVD diamond process over a wide range of reaction conditions. It should find utility in reactor modeling studies, for example in optimizing diamond growth rate while minimizing defect formation. This report also presents a simple model relating the diamond point-defect density to the thermal conductivity of the material.

In US DOE, changing circumstances are affecting the management and disposal of solid, low-level radioactive waste (LLW). From 1977 to 1991, the nuclear power industry achieved major reductions in solid waste disposal, and DOE is interested in applying those practices to reduce solid waste at DOE facilities. Project focus was to identify and document commercial nuclear industry best practices for radiological control programs supporting routine operations, outages, and decontamination and decommissioning activities. The project team (DOE facility and nuclear power industry representatives) defined a Work Control Process Model, collected nuclear power industry Best Practices, and made recommendations to minimize LLW at DOE facilities.

This report discusses work performed under a Cooperative Research And Development Agreement (CRADA) with Corning, Inc., to analyze and test various techniques for controlling the motion of a high speed robotic arm carrying an open container of viscous liquid, in this case, molten glass. A computer model was generated to estimate the modes of oscillation of the liquid based on the shape of the container and the viscosity of the liquid. This fluid model was experimentally verified and tuned based on experimental data from a capacitive sensor on the side of the container. A model of the robot dynamics was also developed and verified through experimental tests on a Fanuc S-800 robot arm. These two models were used to estimate the overall modes of oscillation of an open container of liquid being carried by a robot arm. Using the estimated modes, inverse dynamic control techniques were used to determine a motion profile which would eliminate waves on the liquid`s surface. Experimental tests showed that residual surface waves in an open container of water at the end of motion were reduced by over 95% and that in-motion surface waves were reduced by over 75%.

Gas-phase processing plays an important role in the commercial production of a number of ceramic powders. These include titanium dioxide, carbon black, zinc oxide, and silicon dioxide. The total annual output of these materials is on the order of 2 million tons. The physical processes involved in gas-phase synthesis are typical of those involved in solution -phase synthesis: chemical reaction kinetics, mass transfer, nucleation, coagulation, and condensation. This report focuses on the work done under a Laboratory-Directed Research and Development (LDRD) project that explored the use of various high pressure techniques for ceramic powder synthesis. Under this project, two approaches were taken. First, a continuous flow, high pressure water reactor was built and studied for powder synthesis. And second, a supercritical carbon dioxide static reactor, which was used in conjunction with surfactants, was built and used to generate oxide powders.

This guide contains basic information needed to produce a SAND report. Its guidelines reflect DOE regulation and Sandia policy. The guide includes basic writing instructions in an annotated sample report; guidance for organization, format, and layout of reports produced by line organizations; and information about conference papers, journal articles, and brochures. The appendixes contain sections on Sandia`s preferred usage, equations, references, copyrights and permissions, and publishing terms.

Results of a joint Sandia National Laboratories, University of New Mexico, and New Mexico Engineering Research Institute project to investigate an architecture implementing real-time monitoring and tracking technologies in the railroad industry is presented. The work, supported by the New Mexico State Transportation Authority, examines a family of smart sensor products that can be tailored to the specific needs of the user. The concept uses a strap-on sensor package, designed as a value-added component, integrated into existing industry systems and standards. Advances in sensor microelectronics and digital signal processing permit us to produce a class of smart sensors that interpret raw data and transmit inferred information. As applied to freight trains, the sensors` primary purpose is to minimize operating costs by decreasing losses due to theft, and by reducing the number, severity, and consequence of hazardous materials incidents. The system would be capable of numerous activities including: monitoring cargo integrity, controlling system braking and vehicle acceleration, recognizing component failure conditions, and logging sensor data. A cost-benefit analysis examines the loss of revenue resulting from theft, hazardous materials incidents, and accidents. Customer survey data are combined with the cost benefit analysis and used to guide the product requirements definition for a series of specific applications. A common electrical architecture is developed to support the product line and permit rapid product realization. Results of a concept validation, which used commercial hardware and was conducted on a revenue-generating train, are also reported.

SARS is a data acquisition system designed to gather and process radar data from aircraft flights. A database of flight trajectories has been developed for Albuquerque, NM, and Amarillo, TX. The data is used for safety analysis and risk assessment reports. To support this database effort, Sandia developed a collection of hardware and software tools to collect and post process the aircraft radar data. This document describes the data reduction tools which comprise the SARS, and maintenance procedures for the hardware and software system.

Brief articles in this issue are entitled: New testing techniques, textiles on the information superhighway, and knowledge preservation; Structural health monitoring techniques and robust analysis tools assess aging and damaged structures; Sandia`s VCSELs (Vertical-Cavity Surface-Emitting Lasers): sparking a laser diode revolution; Fiber-optic instrumentation trims weeks off the wait for cervical cancer test results; DAMA (Demand Activated Manufacturing Architecture) project boosts competitiveness of US textile industry; SEAMIST (Science and Engineering Associates Membrane Instrumentation and Sampling Technique) cuts contamination cleanup costs; RePAVing the roads to the past (Relevant Point of Access Video); and Sandia receives DOE basic energy sciences award for sol-gel achievements.

A workshop was held on April 12 and 13, 1996, to provide a forum for gathering information pertinent to using the information highway (the Internet and the World Wide Web) for materials and processes (M&P) research. The workshop`s objectives were to identify the priority needs of materials and processes researchers that could be addressed through the Internet, to describe the relevant capabilities of the information highway, to review existing applications of the highway in materials research and related fields for lessons learned, and to identify potential opportunities and key issues. The workshop was planned and organized by the Committee on Materials and Processes Research and the Information Highway, which was established by the National Materials Advisory Board (NMAB) of the National Research Council (NRC). The workshop was requested and sponsored by the Defense Reliance Technology Panel for Advanced Materials.

This paper describes a poster presentation on the capabilities of the VNIITF to produce solid oxide fuel cells. Research areas, personnel, technology, and test facilities are described.

Rigid polyurethane foams are used for supports and as encapsulants for electronic assemblies in almost all weapon systems. Mechanical properties (storage, loss, rubbery, and glassy moduli) of three foams are being evaluated; the test scheme is illustrated. Aging tests are also being run on the long-term performance of foams being used in the Russian Fissile Material Container; there was no significant change in the glass transition temperature, glassy modulus, or rubbery modulus after one year of aging.

Heliostat installation and alignment costs will be an important element in future solar power tower projects. The predicted annual performances of on- and-off axis strategies are compared for 95 m{sup 2} flat-glass heliostats and an external, molten-salt receiver. Actual approaches to heliostat alignment that have been used in the past are briefly discussed, and relative strengths and limitations are noted. The optimal approach can vary with the application.

The framework is versatile and the generalized approach has worked well for a suite of evaluations or as a foundation for evaluation tools including developing the SEDSS computer software system for evaluating site safety for EPA Superfund problems, NRC Low-Level Nuclear Waste facility siting, and UMTRA site remediation decisions; iteration through the performance assessment of the Greater Confinement Disposal Facility; and optimizing data collection for DNAPL problems. In particular, the SEDSS computer system makes a portion of these tools accessible for broad scale application. Development of both details of the process and computer tools to support individual steps continues.

Aim of this laboratory-directed research and development (LDRD) project was to develop diamond and/or diamond-like carbon (DLC) films for electronic applications. Quality of diamond and DLC films grown by chemical vapor deposition (CVD) is not adequate for electronic applications. Nucleation of diamond grains during growth typically results in coarse films that must be very thick in order to be physically continuous. DLC films grown by CVD are heavily hydrogenated and are stable to temperatures {le} 400{degrees}C. However, diamond and DLC`s exceptional electronic properties make them candidates for integration into a variety of microelectronic structures. This work studied new techniques for the growth of both materials. Template layers have been developed for the growth of CVD diamond films resulting in a significantly higher nucleation density on unscratched or unprepared Si surfaces. Hydrogen-free DLC with temperature stability {le} 800{degrees}C has been developed using energetic growth methods such as high-energy pulsed-laser deposition. Applications with the largest system impact include electron-emitting materials for flat-panel displays, dielectrics for interconnects, diffusion barriers, encapsulants, and nonvolatile memories, and tribological coatings that reduce wear and friction in integrated micro-electro-mechanical devices.

The Radiological Environment Modeling System (REMS) quantifies dose to humans working in radiological environments using the IGRIP (Interactive Graphical Robot Instruction Program) and Deneb/ERGO simulation software. These commercially available products are augmented with custom C code to provide radiation exposure information to, and collect radiation dose information from, workcell simulations. Through the use of any radiation transport code or measured data, a radiation exposure input database may be formulated. User-specified IGRIP simulations utilize these databases to compute and accumulate dose to programmable human models operating around radiation sources. Timing, distances, shielding, and human activity may be modeled accurately in the simulations. The accumulated dose is recorded in output files, and the user is able to process and view this output. The entire REMS capability can be operated from a single graphical user interface.

RADTRAN is a computer code for estimating the risks and consequences as transport of radioactive materials (RAM). RADTRAN was developed and is maintained by Sandia National Laboratories for the US Department of Energy (DOE). For incident-free transportation, the dose to persons exposed while the shipment is stopped is frequently a major percentage of the overall dose. This dose is referred to as Stop Dose and is calculated by the Stop Model. Because stop dose is a significant portion of the overall dose associated with RAM transport, the values used as input for the Stop Model are important. Therefore, an investigation of typical values for RADTRAN Stop Parameters for truck stops was performed. The resulting data from these investigations were analyzed to provide mean values, standard deviations, and histograms. Hence, the mean values can be used when an analyst does not have a basis for selecting other input values for the Stop Model. In addition, the histograms and their characteristics can be used to guide statistical sampling techniques to measure sensitivity of the RADTRAN calculated Stop Dose to the uncertainties in the stop model input parameters. This paper discusses the details and presents the results of the investigation of stop model input parameters at truck stops.

The Transportation Technology Department of Sandia National Laboratories develops analytical and computational tools for the US Department of Energy to assess the radiological consequences and risks from the transportation of radioactive materials by all modes. When large quantities of materials are to be transported movements may occur over an extended period of time in what is collectively referred as a ``shipping campaign``. Since the routes over which the shipments occur often remain the same, cumulative exposure to individuals inhabiting the population zones adjacent to the transport links must be estimated. However, individuals do not remain in the same residences throughout their lifetimes and, in fact, move quite often. To appropriately allocate exposures among populations over extended periods of time, perhaps years, requires a model that accounts for three population categories; (1) the original populations residing in the areas adjacent to the transport links, (2) individuals moving out and (3) individuals moving into residences in the designated areas. The model described here accounts for these conditions and will be incorporated as a user option in the RADTRAN computer code for transportation consequence and risk analysis (Reference 1). RADTRAN is a computer code for estimating the consequences and risks associated with the transport of radioactive materials.

This paper discusses a new approach to the development of engineering education materials. The ``Electronic Textbook`` represents the logical progression of the printed textbook in the Electronic Age. The concept behind this approach is simple; to place all of the information contained in a textbook in electronic form. Currently, paper texts exist on the market with electronic supplements, however, this Electronic Textbook would include supplements fully integrated in the whole text. The computer hardware and software needed to make this advance possible have existed for nearly ten years, and they have been readily available to engineering educators and students for over three years. Computer based ``tools`` in engineering textbooks as are prevalent today range from computer styled algorithms and code snippets, to fully developed software applications with graphical user interfaces on floppy disks attached to the back covers of books. The next logical step in publishing is to dispense with the paper book entirely, by distributing textbooks via electronic media such as CD-ROM. Electronic Textbooks use the full range of multi-media technologies in the learning and teaching process including video clips, computer animations and fully functional numerical engines as integral parts of the textbook material. This is very appealing since interactive media provide teaching tools that appeal to divergent learning styles. The advantages of Electronic Textbooks lead to several challenges. Special attention must be paid to the development of user interfaces; navigation is of particular importance when non- linear exploration is encouraged. These issues are being addressed at the Sandia National Laboratories by an electronic documentation development team. This team includes experts in engineering, in human factors, and in computer hardware and software development. Guidelines for the development of electronic textbooks based on the experiences of this team are provided.

A range-to-target algorithm for application to targets which exhibit a crude hyperbolic wiggle trace is described. The current practice is to use the apex time of the hyperbolic response together with an estimate of the propagation velocity to furnish the range. This new algorithm minimizes a difference function over a velocity search interval to provide the range. Examples for a variety of media, targets, range, and operating frequency are given for both simulated data and actual field data provided by others. Generally, the range is within 5% of the true value when known, or is consistent with values furnished by others.

A new class of inorganic ion exchangers called crystalline silicotitanates (CST), invented by researchers at Sandia National Laboratories and Texas A&M University, has been commercialized in a joint Sandia-UOP effort. The original developmental materials exhibited high selectivity for the ion exchange of cesium, strontium, and several other radionuclides from highly alkaline solutions containing molar concentrations of Na{sup +}. The materials also showed excellent chemical and radiation stability. Together, the high selectivity and stability of the CSTs made them excellent candidates for treatment of solutions such as the Hanford tank supernates and other DOE radwastes. Sandia National Laboratories and UOP have teamed under a Cooperative Research and Development Agreement (CRADA) to develop CSTs in the powdered form and in an engineered form suitable for column ion exchange use. A continuous-flow, column ion exchange process is expected to be used to remove Cs and other radionuclides from the Hanford supernatant. The powder material invented by the Sandia and Texas A&M team consists of submicron-size particles. It is not designed for column ion exchange but may be used in other applications.

In finite-element, transient dynamics simulations, physical objects are typically modeled as Lagrangian meshes because the meshes can move and deform with the objects as they undergo stress. In many simulations, such as computations of impacts or explosions, portions of the deforming mesh come in contact with each other as the simulation progresses. These contacts must be detected and the forces they impart to the mesh must be computed at each timestep to accurately capture the physics of interest. While the finite-element portion of these computations is readily parallelized, the contact detection problem is difficult to implement efficiently on parallel computers and has been a bottleneck to achieving high performance on large parallel machines. In this paper we describe a new parallel algorithm for detecting contacts. Our approach differs from previous work in that we use two different parallel decompositions, a static one for the finite element analysis and dynamic one for contact detection. We present results for this algorithm in a parallel version of the transient dynamics code PRONTO-3D running on a large Intel Paragon.

This study has demonstrated the feasibility of TiO{sub 2} photocatalysis to treat EDTA and several metal-EDTA complexes that can be found in industrial wastewaters. For the EDTA complexes of metals capable of photodeposition, such as Cu and Pb, certain reaction conditions were shown to facilitate the simultaneous complex degradation and photodeposition of these metals onto the catalyst. With metals that do not easily photodeposit, such as Ni and Cd, it is shown that the complex degradation is still facilitated, and can enhance other metals removal processes after photocatalytic treatment. Because the treatment of these metal-EDTA complexes typically requires special measures, there may exist situations where TiO{sub 2} photocatalysis could actually be the preferred method of treatment. However, its use should be compared economically to other more established advanced oxidation technologies. This necessity is demonstrated in the economic comparison to ozone treatment for EDTA degradation alone, where ozone treatment appears to be the clear choice in this application.

Short communication.

Problems in environmental restoration that involve detecting or monitoring contamination or site characterization often benefit from procedures that help select sampling or drilling locations for obtaining meaningful data that support the analysis. One example of this type of procedure is a spatial sampling program that will ``automatically`` (based on the implementation of a computer algorithm) guide an iterative investigation through the process of site characterization at a minimal cost to determine appropriate remediation activities. In order to be effective, such a procedure should translate site and modeling uncertainties into terms that facilitate comparison with regulations and should also provide a methodology that will lead to an efficient sampling plan over the course of the analysis. In this paper, a general framework is given that can accomplish these objectives and can be applied to a wide range of environmental restoration applications. The methodology is illustrated using an example where soil samples support the characterization of a chemical waste landfill area.