Publications

The U.S. Department of Energy`s Office of Technology Development has been developing robotics and automation technologies for the clean-up and handling of hazardous and radioactive waste through one of its major elements, Cross Cutting and Advanced Technology development. CC&AT university research and development programs recognize the strong technology, base resident in the university community and sponsor a focused technology research and development program which stresses close interaction between the university sector and the DOE community. This report contains a compilation of research articles by each of 14 principle investigators supported by CC&AT to develop robotics and automation technologies for the clean-up and handling of hazardous and radioactive waste. This research has led to innovative solutions for waste clean-up problems, and it has moved technology out of university laboratories into functioning systems which has allowed early evaluation by site technologists.

We present a motion planner for the classical mover`s problem in three dimensions that is both resolution-complete and efficient in that it has performance commensurate with task difficulty. It is based on the SANDROS search strategy, which uses a hierarchical, multi-resolution representation of the configuration space along with a generate-and-test paradigm for solution paths. This planner can control the trade-offs between the computation resource and algorithmic completeness/solution path quality, and thus can fully utilize the available computing power. It is useful for navigation of mobile robots, submarines and spacecraft, or part motion feasibility in assembly planning.

A percolation model is developed which accounts for most known features of the process of porous glass membrane preparation by selective dissolution of multi-component glasses. The model is founded within tile framework of the classical percolation theory, wherein the components of a glass are represented by random sites on a suitable lattice. Computer simulation is used to mirror the generation of a porous structure during the dissolution process, reproducing many of the features associated with the phenomenon. Simulation results evaluate the effect of the initial composition of the glass on the kinetics of the leaching process as well as the morphology of the generated porous structure. The percolation model establishes the porous structure as a percolating cluster of unreachable constituents in the glass. The simulation algorithm incorporates removal of both, the accessible leachable components in the glass as well as the independent clusters of unreachable components not attached to the percolating cluster. The dissolution process thus becomes limited by the conventional site percolation thresholds of the unreachable components (which restricts the formation of the porous network), as well as the leachable components (which restricts the accessibility of the solvating medium into the glass). The simulation results delineate the range of compositional variations for successful porous glass preparation and predict the variation of porosity, surface area, dissolution rates and effluent composition with initial composition and time. Results compared well with experimental studies and improved upon similar models attempted in die past.

Emissive flat panel display systems operating in full color demand higher performance at low voltages (ca. 501000 V) from cathodoluminescent (CL) phosphors than cathode ray tubes require. Hydrothermal synthesis has been suggested as a route to phosphors with improved efficiencies, lower voltage thresholds, and increased saturation power. This hypothesis was tested in europium-doped yttrium orthovanadate (YVO{sub 4}:Eu), an efficient, red emitting CL phosphor. The CL efficiency of YVO{sub 4}:Eu crystallized from aqueous solution at 200{degrees}C is relatively low until it is annealed. The distribution of particle sizes in the low-temperature phosphor is similar to that in material made via a solid-state route, but crystallites remain much smaller (ca. 400 {Angstrom}) until they are annealed. These observations, along with the anomalously strong dependence of CL intensity on europium concentration, support a model in which efficiency principally depends on crystallite size. CL efficiency of both solid state and hydrothermal YVO{sub 4}:Eu increases with voltage at constant power. Surface-bound electrons are likely the dominant influence on efficiency at voltages near threshold. Saturation power is independent of synthetic route. It is apparent that the CL properties of hydrothermally synthesized YVO{sub 4}:Eu are essentially the same as those of YVO{sub 4}:Eu produced via conventional, high-temperature routes.

To address the need for a fast path planner, we present a learning algorithm that improves path planning by using past experience to enhance future performance. The algorithm relies on an existing path planner to provide solutions difficult tasks. From these solutions, an evolving sparse work of useful robot configurations is learned to support faster planning. More generally, the algorithm provides a framework in which a slow but effective planner may be improved both cost-wise and capability-wise by a faster but less effective planner coupled with experience. We analyze algorithm by formalizing the concept of improvability and deriving conditions under which a planner can be improved within the framework. The analysis is based on two stochastic models, one pessimistic (on task complexity), the other randomized (on experience utility). Using these models, we derive quantitative bounds to predict the learning behavior. We use these estimation tools to characterize the situations in which the algorithm is useful and to provide bounds on the training time. In particular, we show how to predict the maximum achievable speedup. Additionally, our analysis techniques are elementary and should be useful for studying other types of probabilistic learning as well.

The contact between an obsidian flow and a steep-walled tuff canyon was examined as an analogue for a high-level waste repository. The analogue site is located in the Valles Caldera in New Mexico, where a massive obsidian flow filled a paleocanyon in the Battleship Rock Tuff. The obsidian flow provided a heat source, analogous to waste panels or an igneous intrusion in a repository, and caused evaporation and migration of water. The tuff and obsidian samples were analyzed for major and trace elements and mineralogy by INAA, XRF, x-ray diffraction, and scanning electron microscopy and electron microprobe. Samples were also analyzed for D/H and {sup 39}Ar/{sup 40}Ar isotopic composition. Overall, the effects of the heating event seem to have been slight and limited to the tuff nearest the contact. There is some evidence of devitrification and migration of volatiles in the tuff within 10 m of the contact, but variations in major and trace element chemistry are small and difficult to distinguish from the natural (pre-heating) variability of the rocks.

The sorption of Cs and Cd on model soil minerals was examined by complementary analytical and experimental procedures. X-ray photoelectron spectroscopy (XPS) and nuclear magnetic resonance (NMR) spectroscopy were used to characterize the chemical and physical nature of Cs-reacted soil minerals. Cd and Cs adsorption isotherms for kaolinite were also measured at variable pH and temperature to establish likely reaction stoichiometries, while atomic force microscopy (AFM) was used to characterize the microtopography of the clay surface. XPS analyses of Cs-exchanged samples show that Cs is sorbed at mineral surfaces and at the interlayer site of smectite clays, although the spectral resolution of XPS analyses is insufficient to differentiate between basal, edge or interlayer sites. {sup 133}Cs MAS-NMR results also show that Cs is adsorbed primarily in an interlayer site of montmorillonite and on edge and basal sites for kaolinite. Cd adsorption isotherms on kaolinite were found to be additive using Al{sub 2}0{sub 3} + Si0{sub 2} Cd binding constants. AFM quantification of kaolinite crystallites suggest that edges comprise up to 50% of the BET surface area, and are consistent with NMR and surface charge results that Cs an Cd adsorption occur primarily at edge sites.

Sandia National Laboratories has worked with Synthetica Technologies and Manufacturing and Technology Conversion International (MTCl) to demonstrate the applicability of their commercial steam reforming technologies for treating DOE low-level mixed wastes. Previously, Synthetica successfully demonstrated destruction of a Sandia formulated lab trash simulant. During November 1994 Synthetica did not adequately process the aqueous halogenated organic liquid mixed waste simulant (MWTP-2110) formulated by the DOE Mixed Waste Integrated Program (MWIP). Testing at MTCl is ongoing and initial results appear to be favorable. Approximately 200 lbs each of the MWIP aqueous halogenated organic liquids (MWTP-2110), and absorbed aqueous and organic liquids (MWTP-3113/3114) simulants have been processed. At 1650{degree}F, destruction efficiencies of greater than 99% were obtained for tetrachloroethylene, toluene, and 1,2 dichlorobenzene. Product cases consisted primarily of H{sub 2}, C0{sub 2}, CO, and CH{sub 4} and had higher heating values of up to 355 BTU/SCF. Conclusions concerning the suitability of the MTCI process for treating DOE mixed wastes will be drawn upon the completion of testing.

Public concerns about surface water quality and its impact on health issues have put a premium on the ability to predict surface and groundwater quality in urban areas. The movement of toxins and nutrients in urban areas is largely controlled by interactions with soil and aquifer minerals along hydrologic pathways. Despite progress in theoretical modeling of the effects of these interactions on water chemistry, it is presently impossible to predict overall trends in urban water quality. Determining the controls on stream water chemistry is problematic due to the interplay between different hydrologic reservoirs which cannot be easily observed or measured. Natural tracers, such as dissolved ions and isotopes, provide an indirect method for observing subsurface interactions and are useful for time series analysis of stream water composition. Ionic species are generally nonconservative components because of chemical reactions and are thus useful for discerning the overall discharge chemistry affected by the relationship.

The primary purpose of this paper is to provide a careful evaluation of the diffusion velocity concept with regard to its ability to predict the diffusion of vorticity near a moving wall. A computer code BDIF has been written which simulates the evolution of the vorticity field near a wall of infinite length which is moving in an arbitrary fashion. The simulations generated by this code are found to give excellent results when compared to several exact solutions. We also outline a two-dimensional unsteady viscous boundary layer model which utilizes the diffusion velocity concept and is compatible with vortex methods. A primary goal of this boundary layer model is to minimize the number of vortices generated on the surface at each time step while achieving good resolution of the vorticity field near the wall. Preliminary results have been obtained for simulating a simple two-dimensional laminar boundary layer.

Sol-gel processing has been widely used in the preparation of lead zirconate titanate (PZT) thin films. The authors have applied this methodology to the formation of lead magnesium niobate (PMN) spin-cast deposited thin films. Since there is a limited number of soluble, commercially available compounds, the authors have recently synthesized a series of novel metal alkoxides for use as precursors for generation of PMN thin films and powders. The process for generation of the perovskite phase of these PMN powders and films are reported.

The numerical code TOUGH2 was used to assess alternative conceptual models of fracture flow. The models that were considered included the equivalent continuum model (ECM) and the dual permeability (DK) model. A one-dimensional, layered, unsaturated domain was studied with a saturated bottom boundary and a constant infiltration at the top boundary. Two different infiltration rates were used in the studies. In addition, the connection areas between the fracture and matrix elements in the dual permeability model were varied. Results showed that the two conceptual models of fracture flow produced different saturation and velocity profiles-even under steady-state conditions. The magnitudes of the discrepancies were sensitive to two parameters that affected the flux between the fractures and matrix in the dual permeability model: (1) the fracture-matrix connection areas and (2) the capillary pressure gradients between the fracture and matrix elements.

This paper discusses, in a general way, the influence of technology on the economy. The target audience is engineers who are involved in technology development but who are not especially familiar with economics. The measure used for describing the health of an economy is productivity. The impact of technological developments on productivity is discussed.

Hazardous materials management includes interactions among materials, personnel, facilities, hazards, and processes of various groups within a DOE site`s environmental, safety & health (ES&H) and line organizations. Although each group is charged with addressing a particular aspect of these properties and interactions, the information it requires must be gathered into a coherent set of common data for accurate and consistent hazardous material management and regulatory reporting. It is these common data requirements which the Cradle-to-Grave Tracking and Information System (CGTIS) is designed to satisfy. CGTIS collects information at the point at which a process begins or a material enters a facility, and maintains that information, for hazards management and regulatory reporting, throughout the entire life-cycle by providing direct on-line links to a site`s multitude of data bases to bring information together into one common data model.

The RADTRAN computer code for transportation risk analysis, which has been under continuous development at Sandia National Laboratories since 1977, has evolved from a purely research tool into a publicly available with a variety of applications. This expansion of the user community has substantially increased the need to make the system easier to use without decreasing its capabilities or the quality of output. A large set of modifiable RADTRAN input files has been available via TRANSNET for several years. One approach to assisting the user involves adding annotations/information to each of these files. A second approach is providing additional help in building new/modifying old input files. Keeping the proposed information/annotation files separate from but closely coupled to the modifiable input files within the TRANSNET shell system allows the modifiable input files to remain as regular input files while providing rapid, automatic access to, useful information about the analysis. In this way, the sample input files remain intact as regular RADTRAN input files and any files generated using associated on-line menus or editors may be readily converted into new input files. A single sample file is selected and used as an example to illustrate the prototype help features.

Scenario development for the system performance assessment of the Yucca Mountain Site Characterization Project defines a scenario as a well-posed problem connecting an initiating event with radionuclide release to the accessible environment by a logical and physically possible combination or sequence of features, events, and processes. Drawing on the advice and assistance of the Project`s principal investigators (PIs), a collection of release scenarios initiated by the nominal ground-water flow occurring in the vicinity of the potential Yucca Mountain high-level-waste repository is developed and described in pictorial form. This collection of scenarios is intended to provide a framework to assist PIs in recognizing essential field and calculational analyses, to assist performance assessment in providing guidance to site characterization, and to continue the effort to exhaustively identify all features, events, and processes important to releases. It represents a step in the iterative process of identifying what details of the potential site are important for safe disposal. 67 refs.

Correct operation of an information system requires a balance of ``surety`` domains -- access control (confidentiality), integrity, utility, availability, and safety. However, traditional approaches provide little help on how to systematically analyze and balance the combined impact of surety requirements on a system. The key to achieving information system surety is identifying, prioritizing, and mitigating the sources of risk that may lead to system failure. Consequently, the authors propose a risk assessment methodology that provides a framework to guide the analyst in identifying and prioritizing sources of risk and selecting mitigation techniques. The framework leads the analyst to develop a risk-based system model for balancing the surety requirements and quantifying the effectiveness and combined impact of the mitigation techniques. Such a model allows the information system designer to make informed trade-offs based on the most effective risk-reduction measures.

The agile manufacturing paradigm engenders many new concepts and work approaches for manufacturing operations. A technology often invoked in the concept of agility is modeling and simulation. Few would disagree that modeling and simulation holds the potential to substantially reduce the product development cycle and lead to improve product reliability and performance. Advanced engineering simulation can impact manufacturing in three areas: process design, product design, and process control. However, despite that promise, the routine utilization of modeling and simulation by industry within the design process is very limited. Advanced simulation is still used primarily in a troubleshooting mode examining design or process problems after the fact. Sandia National Laboratories has been engaged in the development of advanced engineering simulation tools for many years and more recently has begun to focus on the application of such models to manufacturing processes important for the defense industry. These efforts involve considerable interaction and cooperative research with US industry. Based upon this experience, this presentation examines the elements that are necessary for advanced engineering simulation to become an integral part of the design process.

This paper presents experimental data and computational modeling for a well-defined glass material. The experimental data cover a wide range of strains, strain rates, and pressures that are obtained from quasi-static compression and tension tests, split Hopkinson pressure bar compression tests, explosively driven flyer plate impact tests, and depth of penetration ballistic tests. The test data are used to obtain constitutive model constants for the improved Johnson-Holmquist (JH-2) brittle material model. The model and constants are then used to perform computations of the various tests.

At Sandia National Laboratories in Albuquerque, the author designed and fabricated a precision wire feeder to be used with high energy density (electron beam and laser beam) welding for weld joints where filler wire might be needed to fill a gap or to adjust the chemical composition so that a crack-free weld could be made. The wire feeder incorporates a 25,000 step-per-revolution motor to power a urethane-coated drive roll. A microprocessor-based controller provides precise control of the motor and allows both continuous and pulsed feeding of the wire. A unidirectional 0.75-in.-dia ball bearing is used to press the wire against the drive roll. A slight constant backward tension is maintained on the wire spool by a Bodine torque motor. A Teflon tube is used to guide the wire from the drive roll to the vicinity of the weld, where a hypodermic needle is used to aim the wire into the weld pool. The operation of the wire feeder was demonstrated by feeding a 10-mil-dia, Type 304 stainless steel wire into a variety of CO{sub 2} laser beam welds. The resulting welds are smooth and continuous, and the welds are considered to be completely satisfactory for a variety of applications.

Several government agencies and industrial sectors have recognized the need for, and payoff of, investing in the methodologies and associated technologies for improving the product realization process. Within the defense community as well as commercial industry, there are three major needs. First, they must reduce the cost of military products, of related manufacturing processes, and of the enterprises that have to be maintained. Second, they must reduce the time required to realize products while still applying the latest technologies. Finally, they must improve the predictability of process attributes, product performance, cost, schedule and quality. They must continue to advance technology, quickly incorporate their innovations in new products and in processes to produce them, and they need to capitalize on the raw computational power and communications bandwidth that continues to become available at decreasing cost. Sandia National Laboratories initiative is pursuing several interrelated, key concepts and technologies in order to enable such product realization process improvements: model-based design; intelligent manufacturing processes; rapid virtual and physical prototyping; and agile people/enterprises. While progress in each of these areas is necessary, this paper only addresses a portion of the overall initiative. First a vision of a desired future capability in model-based design and virtual prototyping is presented. This is followed by a discussion of two specific activities parametric design analysis of Synthetic Aperture Radars (SARs) and virtual prototyping of miniaturized high-density electronics -- that exemplify the vision as well as provide a status report on relevant work in progress.

One of the tasks of the Lethality Group within US Army Space and Strategic Defense Command (USASSDC) is the development of a capability to simulate various missile intercept scenarios using computer codes. Currently under development within USASSDC and its various contractor organizations is a group of codes collected under a master code called PEGEM for Post Event Ground Effects Model. Among the various components of the code are modules which are used to predict atmospheric dispersion and transport of particles or droplets following release at the altitude specified in the missile intercept scenario. The atmospheric transport code takes into account various source term data from the intercept such as: initial cloud size; droplet or particle size distribution; and, total mass of agent released. An ongoing USASSDC experimental program termed Crystal Mist involved release of precision glass beads under various altitude and meteorological conditions to assist in validation and refinement of various codes that are components of PEGEM used to predict particle atmospheric transport and diffusion following a missile intercept. Here, soda-lime glass beads used in the Crystal Mist series of atmospheric transport and diffusion tests were characterized by scanning electron microscopy and automated image processing routines in order to fully define their size distributions and morphology. Four bead size classifications ranging from a median count diameter of 45 to 200 micrometers were found to be approximately spherical and to fall within the supplier`s sizing specifications. Log-normal functions fit to the measured size distributions resulted in geometric standard deviations ranging from 1.08 to 1.12, thereby fulfilling the field trial requirements for a relatively narrow bead size distribution.

A novel, folded compact range configuration has been developed at the Sandia National Laboratories compact range antenna and radar cross section measurement facility, operated by the Radar/Antenna Department 2343, as a means of performing indoor, environmentally-controlled, far-field simulations of synthetic aperture radar (SAR) coherent change detection (CCD) measurements. This report describes the development of the folded compact range configuration, as well as the initial set of coherent change detection measurements made with the system. These measurements have been highly successful, and have demonstrated the viability of the folded compact range concept in simulating SAR CCD measurements. It is felt that follow-on measurements have the potential of contributing significantly to the body of knowledge available to the scientific community involved in CCD image generation and processing, and that this tool will be a significant aid in the research and development of change detection methodologies.

This report summarizes a number of research efforts completed over the past 20 years in the El Paso del Norte region to characterize pollution sources and air quality trends. The El Paso del Norte region encompasses the cities of El Paso, Texas and Ciudad Juarez, Chihuahua and is representative of many US-Mexico border communities that are facing important air quality issues as population growth and industrialization of Mexican border communities continue. Special attention is given to a group of studies carried out under special US Congressional funding and administered by the US Environmental Protection Agency. Many of these studies were fielded within the last several years to develop a better understanding of air pollution sources and trends in this typical border community. Summary findings from a wide range of studies dealing with such issues as the temporal and spatial distribution of pollutants and pollution potential from both stationary and mobile sources in both cities are presented. Particular emphasis is given to a recent study in El Paso-Ciudad Juarez that focussed on winter season PM{sub 10} pollution in El Paso-Ciudad Juarez. Preliminary estimates from this short-term study reveal that biomass combustion products and crustal material are significant components of winter season PM{sub 10} in this international border community.

This report summarizes the activities of a Lab Directed Research and Development (LDRD) Project to investigate the viability of asynchronous transfer mode (ATM) switching technology in the local area network (LAN) environment. A number of ATM based LANs were constructed and their performance capabilities were measured. The summary report notes the measurements and lessons learned from the two-year effort.

In today`s world, accurate finite-element simulations of large nonlinear systems may require meshes composed of hundreds of thousands of degrees of freedom. Even with today`s fast computers and the promise of ever-faster ones in the future, central processing unit (CPU) expenditures for such problems could be measured in days. Many contemporary engineering problems, such as those found in risk assessment, probabilistic structural analysis, and structural design optimization, cannot tolerate the cost or turnaround time for such CPU-intensive analyses, because these applications require a large number of cases to be run with different inputs. For many risk assessment applications, analysts would prefer running times to be measurable in minutes. There is therefore a need for approximation methods which can solve such problems far more efficiently than the very detailed methods and yet maintain an acceptable degree of accuracy. For this purpose, we have been working on two methods of approximation: neural networks and spring-mass models. This paper presents our work and results to date for spring-mass modeling and analysis, since we are further along in this area than in the neural network formulation. It describes the physical and numerical models contained in a code we developed called STRESS, which stands for ``Spring-mass Transient Response Evaluation for structural Systems``. The paper also presents results for a demonstration problem, and compares these with results obtained for the same problem using PRONTO3D, a state-of-the-art finite element code which was also developed at Sandia.

Traditional approaches to the assessment of information systems have treated system security, system reliability, data integrity, and application functionality as separate disciplines. However, each areas requirements and solutions have a profound impact on the successful implementation of the other areas. A better approach is to assess the ``surety`` of an information system, which is defined as ensuring the ``correct`` operation of an information system by incorporating appropriate levels of safety, functionality, confidentiality, availability, and integrity. Information surety examines the combined impact of design alternatives on all of these areas. We propose a modelling approach that combines aspects of fault trees and influence diagrams for assessing information surety requirements under a risk assessment framework. This approach allows tradeoffs to be based on quantitative importance measures such as risk reduction while maintaining the modelling flexibility of the influence diagram paradigm. This paper presents an overview of the modelling method and a sample application problem.

A thermomechanical analysis of a continuous fiber metal matrix composite (MMC) subjected to cyclic loading is performed herein. The analysis includes the effects of processing induced residual thermal stresses, matrix inelasticity, and interface cracking. Due to these complexities, the analysis is performed computationally using the finite element method. Matrix inelasticity is modelled with a rate dependent viscoplasticity model. Interface fracture is modelled by the use of a nonlinear interface constitutive model. The problem formulation is summarized, and results are given for a four-ply unidirectional SCS-6/{beta}21S titanium composite under high temperature isothermal mechanical fatigue. Results indicate rate dependent viscoplasticity can be a significant mechanism for dissipating the energy available for damage propagation, thus contributing to improved ductility of the composite. Results also indicate that the model may be useful for inclusion in life prediction methodologies for MMC`s.

In this paper a brief description of dynamic techniques commonly available for determining material property studies is presented. For many impact applications, the material generally experiences a complex loading path. In most cases, the initial loading conditions can be represented by the shock commonly referred to as the Hugoniot state. Subsequent loading or release structure, i.e., off-Hugoniot states would however be dependent on the physical processes dominating the material behavior. The credibility of the material model is tested by the accuracy of predictions of off-Hugoniot states. Experimental techniques commonly used to determine off-Hugoniot states are discussed in this survey.

There has been some concern that, as nuclear power plants age, protective measures taken to control and minimize the impact of fire may become ineffective, or significantly less effective, and hence result in an increased fire risk. One objective of the Fire Vulnerability of Aged Electrical Components Program is to assess the effects of aging and service wear on the fire vulnerability of electrical equipment. An increased fire vulnerability of components may lead to an overall increase in fire risk to the plant. Because of their widespread use in various electrical safety systems, electromechanical relays were chosen to be the initial components for evaluation. This test program assessed the impact of operational and thermal aging on the vulnerability of these relays to fire-induced damage. Only thermal effects of a fire were examined in this test program. The impact of smoke, corrosive materials, or fire suppression effects on relay performance were not addressed in this test program. The purpose of this test program was to assess whether the fire vulnerability of electrical relays increased with aging. The sequence followed for the test program was to: identify specific relay types, develop three fire scenarios, artificially age several relays, test the unaged and aged relays in the fire exposure scenarios, and compare the results. The relays tested were Agastat GPI, General Electric (GE) HMA, HGA, and HFA. At least two relays of each type were artificially aged and at least two relays of each type were new. Relays were operationally aged by cycling the relay under rated load for 2,000 operations. These relays were then thermally aged for 60 days with their coil energized.

An approach is described for performing scoping calculations of radionuclide release fractions from target materials being considered for use in the Accelerator Production of Tritium (APT) project, and some illustrative results are presented. The releases are evaluated for postulated accident scenarios involving severe overheating of either of two neutron source target materials, tungsten and lead. The potential for vaporization of radionuclides produced by spallation and neutron capture reactions is evaluated using a model that includes production of volatile species by reaction with steam, hydrogen, and/or oxygen. Emphasis is on release from the neutron source materials themselves, with a more limited treatment being given for radionuclides produced in other parts of the target/blanket assemblies. In the tungsten neutron source target, the low rate of diffusion within the tungsten is shown to limit releases of even volatile species to small values in a chemically inert or reducing environment. However, oxidative ablation of tungsten could permit considerably larger releases of volatile species in steam-rich or oxygen-rich environments. Tungsten radionuclides would dominate the source term for accident conditions considered the most plausible. For the lead neutron source target, the releases are predicted to be dominated by mercury radionuclides. Quantitative source term evaluation for this target is complicated because, in any accident sufficiently severe to be of much concern, lead melting will likely result in loss of target geometry. Hence, results presented for release from the lead must be carefully qualified. Extensive parametric results are presented for release from both neutron source materials. These results may be used to perform scoping estimates of radionuclide releases for additional APT accident scenarios as the controlling parameters for these scenarios become better defined.

The majority of all oil well footage drilled is in shales and other clay-bearing rocks. The mechanical strength of these formations usually is not an issue as regards their fast penetration by the drill bit. The difficulties associated with these formations arise due to the chemically reactive nature of such formations, causing the cuttings to stick to the bit. This causes a decrease in the rate of penetration of the drill bit and also has a detrimental effect on the state of the wellbore. This report presents a radical approach to preventing the adherence of shale cuttings to the bit. It consists of applying a direct electrical potential between the rock and the bit while drilling, while making the latter the cathode. Due to the process of electro-osmosis that occurs in shales, this results in the migration of a thin layer of water to the interface between the metal body (cathode) and the rock (anode). It has been demonstrated that this layer of water at the interface aids in the penetration of single-point indenters and also facilitates their withdrawal. Interfacial friction between a shale and a metal body was reduced, as was the tendency of shale cuttings to adhere to the metal surface. All of these combined to cause significant increases in the rate of penetration of a cathodic bit, as compared to the case when no potential was applied. It has been shown that when the bit was made the cathode, the maximum advantage was obtained when drilling conditions got worse, making it ideally suited for field applications. It was also shown that in the time intervals relevant to drilling operations, an amount of water sufficient to provide a coating on the bit was migrated out of a shale. It is believed that since the contact between the metal and the shale completes the electrical circuit to produce the driving force, this technique should work under most operating conditions. 63 refs.

Sandia National Laboratories, New Mexico, conducts the Utility Battery Storage Systems Program, which is sponsored by the US Department of Energy`s Office of Energy Management. The goal of this program is to assist industry in developing cost-effective battery systems as a utility resource option by 2000. Sandia is responsible for the engineering analyses, contracted development, and testing of rechargeable batteries and systems for utility energy storage applications. This report details the technical achievements realized during fiscal year 1994.

The purpose of this document is to describe a qualitative risk assessment process that supplements the requirements of DOE/AL 5481.1B. Although facility managers have a choice of assessing risk either quantitatively or qualitatively, trade offs are involved in making the most appropriate choice for a given application. The results that can be obtained from a quantitative risk assessment are significantly more robust than those results derived from a qualitative approach. However, the advantages derived from quantitative risk assessment are achieved at a greater expenditure of money, time and convenience. This document provides the elements of a framework for performing a much less costly qualitative risk assessment, while retaining the best attributes of quantitative methods. The approach discussed herein will; (1) provide facility managers with the tools to prepare consistent, site wide assessments, and (2) aid the reviewers who may be tasked to evaluate the assessments. Added cost/benefit measures of the qualitative methodology include the identification of mechanisms for optimally allocating resources for minimizing risk in an expeditious, and fiscally responsible manner.

The Plasma Technology Directory has two main goals: (1) promote, coordinate, and share plasma technology experience and equipment within the Department of Energy; and (2) facilitate technology transfer to the commercial sector where appropriate. Personnel are averaged first by Laboratory and next by technology area. The technology areas are accelerators, cleaning and etching deposition, diagnostics, and modeling.

This paper presents a concept for fusing 3-dimensional image reconnaissance data with LADAR imagery for aim point refinement. The approach is applicable to fixed or quasi-fixed targets. Quasi-fixed targets are targets that are not expected to be moved between the time of reconnaissance and the time of target engagement. The 3-dimensional image data is presumed to come from standoff reconnaissance assets tens to hundreds of kilometers from the target area or acquisitions prior to hostilities. Examples are synthetic aperture radar (SAR) or stereoprocessed satellite imagery. SAR can be used to generate a 3-dimensional map of the surface through processing of data acquired with conventional SAR acquired using two closely spaced, parallel reconnaissance paths, either airborne or satellite based. Alternatively, a specialized airborne SAR having two receiving antennas may be used for data acquisition. The data sets used in this analysis are: (1) LADAR data acquired using a Hughes-Danbury system flown over a portion of Kirtland AFB during the period September 15--16, 1993; (2) two pass interferometric SAR data flown over a terrain-dominated area of Kirtland AFB; (3) 3-dimensional mapping of an urban-dominated area of the Sandia National Laboratories and adjacent cultural area extracted from aerial photography by Vexcel Corporation; (4) LADAR data acquired at Eglin AFB under Wright Laboratory`s Advanced Technology Ladar System (ATLAS) program using a 60 {mu}J, 75 KHz Co{sub 2} laser; and (5) two pass interferometric SAR data generated by Sandia`s STRIP DCS (Data Collection System) radar corresponding to the ATLAS LADAR data. The cultural data set was used in the urban area rather than SAR because high quality interferometric SAR data were not available for the urban-type area.

Finite Element Analysis capability for application to welding has been developed and enhanced during a two year Cooperative Research and Development Agreement(CRADA) between Pratt & Whitney, United Technologies Research Center, and Sandia National Laboratories. Because of the nature of electron beam welding at Pratt & Whitney -- set-up is time consuming, the parts to be welded are complicated, and experimentation is costly -- finite element analysis has found many potential applications. The results of most interest in these analyses are the residual stress and final distortion of the component. The work has made use of the Sandia finite element codes JACQ3D, for thermal analysis, and JAS3D, for mechanical analysis. Both codes use an efficient, non-linear conjugate gradient solution technique, which enables large problems to be solved on engineering workstations. This presentation describes several technical challenges that were overcome in the application of the Sandia codes to this class of problems. Stress and distortion results predicted for an electron beam weld of a PW4000 gas turbine engine drum rotor will also be discussed.

Selecting a risk-based tool to aid in decision making is as much of a challenge as properly using the tool once it has been selected. Failure to consider customer and stakeholder requirements and the technical bases and differences in risk-based decision making tools will produce confounding and/or politically unacceptable results when the tool is used. Selecting a risk-based decisionmaking tool must therefore be undertaken with the same, if not greater, rigor than the use of the tool once it is selected. This paper presents a process for selecting a risk-based tool appropriate to a set of prioritization or resource allocation tasks, discusses the results of applying the process to four risk-based decision-making tools, and identifies the ``musts`` for successful selection and implementation of a risk-based tool to aid in decision making.

Safety is of paramount concern in todays high technology environment. Because of technological advances, there are numerous situations (high consequence operations) for which the implications of a safety failure are so severe that extreme attention to safety systems is essential. Some of those situations are: nuclear weapon detonation safety, nuclear reactor safety, dam safety, mass transit transportation safety, and hazardous materials transportation and handling safety. In each case, specific safety systems, human control, and administrative procedures have been designed to give a high level of assurance against disasters. In an overview sense, safety concepts can be divided into two broad approaches: active safety and passive safety. Active safety systems, in general, are based on the need for ``functioning`` elements (operating motors, operator action, etc.) and safety may be based in a large measure on ``reliability`` data (historical records of the operability success of components). Passive safety basically depends on non-functionality.

With the infusion of information technologies into product development and production processes, effective management of product data is becoming essential to modern production enterprises. When an enterprise-wide Product Data Manager (PDM) is implemented, PDM designers must satisfy the requirements of individual users with different job functions and requirements, as well as the requirements of the enterprise as a whole. Concern must also be shown for the interrelationships between information, methods for retrieving archival information and integration of the PDM into the product development process. This paper describes a user-driven approach applied to PDM design for an agile manufacturing pilot project at Sandia National Laboratories that has been successful in achieving a much faster design-to-production process for a precision electro mechanical surety device.

As industries position themselves for the competitive markets of today, and the increasingly competitive global markets of the 21st century, agility, or the ability to rapidly develop and produce new products, represents a common trend. Agility manifests itself in many different forms, with the agile manufacturing paradigm proposed by the Iacocca Institute offering a generally accepted, long-term vision. In its many forms, common elements of agility or agile manufacturing include: changes in business, engineering and production practices, seamless information flow from design through production, integration of computer and information technologies into all facets of the product development and production process, application of communications technologies to enable collaborative work between geographically dispersed product development team members and introduction of flexible automation of production processes. Industry has rarely experienced as dramatic an infusion of new technologies or as extensive a change in culture and work practices. Human factors will not only play a vital role in accomplishing the technical and social objectives of agile manufacturing. but has an opportunity to participate in shaping the evolution of industry paradigms for the 21st century.

The purpose of an intelligent alarm analysis system is to provide complete and manageable information to a central alarm station operator by applying alarm processing and fusion techniques to sensor information. This paper discusses the sensor fusion approach taken to perform intelligent alarm analysis for the Advanced Exterior Sensor (AES). The AES is an intrusion detection and assessment system designed for wide-area coverage, quick deployment, low false/nuisance alarm operation, and immediate visual assessment. It combines three sensor technologies (visible, infrared, and millimeter wave radar) collocated on a compact and portable remote sensor module. The remote sensor module rotates at a rate of 1 revolution per second to detect and track motion and provide assessment in a continuous 360` field-of-regard. Sensor fusion techniques are used to correlate and integrate the track data from these three sensors into a single track for operator observation. Additional inputs to the fusion process include environmental data, knowledge of sensor performance under certain weather conditions, sensor priority, and recent operator feedback. A confidence value is assigned to the track as a result of the fusion process. This helps to reduce nuisance alarms and to increase operator confidence in the system while reducing the workload of the operator.

Sandia National Laboratories faces institutional challenges that are unique in its history. Never before have the national laboratories been viewed so critically, and never before has their role been the subject of such study and debate. At the same time, the opporunities to render `exceptional service in the national interest` have never been greater. The business of Sandia today and into the foreseeable future will rely on a strong, integrated technical foundation, represented most fundamentally by its core competencies. While is is impossible to foresee precisely what missions Sandia will pursue many years from now, one thing is clear: Central to its service to the nation will be the application of science-based engineering skills to the stewardship of the nuclear weapons stockpile. Whether on not the nation ever builds a new nuclear weapon, those that remain in stockpile will require continuous stewardship based on the integration of scientific understanding with experienced systems engineering. Sandia`s steadfast commitment to DOE`s stockpile stewardship mission will also be evident in the production of limited numbers of certain vital weapon components as the weapons production complex is realigned. Complementing this enduring responsibility will be expanded missions in energy, environment, and economic competitiveness. The work for other federal agencies will be jointly sponsored under high-level agreements with DOE. Multi-institutional teams will become a common way of doing business. The multiprogram laboratory model will evolve toward a new model of multi-laboratory programs addressing major national needs. Sandia will be a distinct and important component of an integrated system of national laboratories.

Extreme UltraViolet Lithography (EUVL) seeks to apply radiation in a wavelength region centered near 13 nm to produce microcircuits having features sizes 0.1 micron or less. A critical requirement for the commercial application of this technology is the development of an economical, compact source of this radiation which is suitable for lithographic applications. A good candidate is a laser-plasma source, which is generated by the interaction of an intermediate intensity laser pulse (up to 10{sup 12} W/cm{sup 2}) with a metallic target. While such a source has radiative characteristics which satisfy the needs of an EUVL source, the debris generated during the laser-target interaction strikes at the economy of the source. Here, the authors review the use of concepts and computer modeling, originally developed for hypervelocity impact analysis, to study this problem.

Environmental regulations are encouraging the development of new environmentally conscious manufacturing (ECNP processes. However, the quality and reliability of these processes and hardware produced must be understood prior to implementing these new technologies in factories. Furthermore, military hardware fabrication is governed by standards and specifications that frequently mandate the use of older, less environmentally friendly processes or materials, or prohibit the use of new ECM processes without advance military approvaL Sandia National Laboratories, with industrial and military partners, have developed methodologies for evaluating and qualifying new ECM processes for military and commercial applications, and have piloted these methodologies in qualifying new, low-residue soldering technologies and materials.

The characteristics of a piezoresistive accelerometer in shock environments are being studied at Sandia National Laboratories in the Mechanical Shock Testing Laboratory. A Hopkinson bar capability has been developed to extend our undemanding of the piezoresistive accelerometer, in two mechanical configurations, in the high frequency, high shock environments where measurements are being made. Two different Hopkinson bar materials are being used: Titanium and beryllium The in-axis performance of the piezoresistive accelerometer for frequencies of dc-10 kHz and shock magnitudes of up to 150,000 g as determined from measurements with a titanium Hopkinson bar are presented. The beryllium Hopkinson bar configuration is described. Preliminary in-axis characteristics of the piezoresistive accelerometer at a nominal shock level of 50,000 g for a frequency range of DC-30 kHz determined from the beryllium bar are presented.

The goal of assembly sequencing is to plan a feasible series of operations to construct a product from its individual parts. Previous research has thoroughly investigated assembly sequencing under the assumption that parts have nominal geometry. This paper considers the case where parts have toleranced geometry. Its main contribution is an efficient procedure that decides if a product admits an assembly sequence with infinite translations that is feasible for all possible instances of the components within the specified tolerances. If the product admits one such sequence, the procedure can also generate it. For the cases where there exists no such assembly sequence, another procedure is proposed which generates assembly sequences that are feasible only for some values of the toleranced dimensions. If this procedure produces no such sequence, then no instance of the product is assemblable. Finally, this paper analyzes the relation between assembly and disassembly sequences in the presence of toleranced parts. This work assumes a simple, but non-trivial tolerance language that falls short of capturing all imperfections of a manufacturing process. Hence, it is only one step toward assembly sequencing with toleranced parts.

A list of computer system components with manufacturer`s model numbers and serial numbers is presented.

There has been some interest lately in the need for ``authenticated signalling``, and the development of signalling specifications by the ATM Forum that support this need. The purpose of this contribution is to show that if authenticated signalling is required, then supporting signalling facilities for directory services (i.e. key management) are also required. Furthermore, this contribution identifies other security related mechanisms that may also benefit from ATM-level signalling accommodations. For each of these mechanisms outlined here, an overview of the signalling issues and a rough cut at the required fields for supporting Information Elements are provided. Finally, since each of these security mechanisms are specified by a number of different standards, issues pertaining to the selection of a particular security mechanism at connection setup time (i.e. specification of a required ``Security Quality of Service``) are also discussed.

A feasibility test on remote monitoring of unattended sensors was conducted by Sandia National Laboratories (SNL) and the Japan Atomic Energy Research Institute (JAERI) under a bilateral agreement between the U.S. Arms Control and Disarmament Agency (ACDA) and JAERI. The Containment and Surveillance Data Authenticated Communication (CASDAC) system developed by JAERI for nuclear safeguards and physical protection is a prototype system for remote monitoring of sensor status through the international telephone network. Sensor inputs to the CASDAC system are provided by prototype tamper-protected sensor enclosures developed by SNL on behalf of ACDA. The CASDAC system normally operates on a polling basis from the central control console at JAERI, but data transmission may also be initiated from the remote read unit at SNL when a sensor activation is detected. All transmission data are encrypted. Statistics concerning reliability, time delay for anomaly detection, and records of all sensor activations were accumulated since May 1992. This paper describes the objectives and preliminary evaluation of the accumulated data. The U.S. Defense Nuclear Agency (DNA) funded the experiment at SNL to obtain information about the potential of CASDAC for use in Chemical Weapons Convention (CWC) applications.

We describe a dynamic load-balancing strategy for parallel finite element methods with adaptive mesh (h-) and order (p-) refinement. The load-balancing algorithm is based on the tiling load-balancing system, where global balance in achieved by performing local balancing within overlapping neighborhoods of processors. Tiling is applied to each mesh level created by the adaptive h-refinement. Weights are used in the migration routines to reflect the nonuniform elemental work loads caused by adaptive p-refinement. The combination of adaptive refinement and tiling significantly reduces total execution time relative to fixed-mesh, fixed-order methods yielding comparable accuracy, as we demonstrate with experiments on an nCUBE/2.

Failure analysis is a critical element in the integrated circuit manufacturing industry. This paper reviews the changing role of failure analysis and describes major techniques employed in the industry today. Several advanced failure analysis techniques that meet the challenges imposed by advancements in integrated circuit technology are described and their applications are discussed. Future trends in failure analysis needed to keep pace with the continuing advancements in integrated circuit technology are anticipated.

Formation of Fe clusters in inverse micelles was studied. Iron salts are solubilized within the polar interior of inverse micelles, and addition of LiBH{sub 4} initiates reduction to produce monodisperse, nanometer-sized Fe based particles. The reaction sequence is sustained by material exchange between inverse micelles. Surfactant interface provides a spatial constraint on reaction volume, and reactions carried out in these micro-heterogeneous solutions produce colloidal sized particles (10--100 {Angstrom}) stabilized in solution against flocculation by surfactant. In this paper, the clusters were characterized using TEM, Moessbauer spectroscopy, electron diffraction, and x-ray photoelectron spectroscopy.

A technology demonstration that optimizes sampling strategies and real-time data collection was carried out at the Kirtland Air Force Base RB-11 Radioactive Burial Site, Albuquerque, New Mexico in August 1994. The project, which was funded by the Strategic Environmental Research and Development Program (SERDP), involved the application of a geostatistical-based {open_quotes}smart sampling{close_quotes} methodology and software with on-site field screening of soils for radiation, organic compounds and metals. The software, known as Plume{trademark}, was developed at Argonne National Laboratory as part of the DOE/OTD-funded Mixed Waste Landfill Integrated Demonstration (MWLID). The objective of the investigation was to compare an innovative Adaptive Sampling approach that stressed real-time decision-making with a conventional RCRA-driven site characterization carried out by the Air Force. The latter investigation used a standard drilling and sampling plan as mandated by the EPA. To make the comparison realistic, the same contractors and sampling equipment (Geoprobe{reg_sign} soil samplers) were used. In both investigations, soil samples were collected at several depths at numerous locations adjacent to burial trenches that contain low-level radioactive waste and animal carcasses. Neither study revealed the presence of contaminants appreciably above risk based action levels, indicating that minimal to no migration has occurred away from the trenches. The combination of Adaptive Sampling with field screening achieved a similar level of confidence compared to the RCRA investigation regarding the potential migration of contaminants at the site. By comparison, the Adaptive Sampling program drilled 28 locations (vs. 36 for the conventional investigation), collected 81 samples (vs. 163), and sent 15 samples (vs. 163) off-site for laboratory analysis. In addition, the field work took 3 1/2 days compared to 13 days for the RCRA investigation.

The A-primed (Agile Product Realization of Innovative electro-Mechanical Devices) project is defining and proving processes for agile product realization for the Department of Energy complex. Like other agile production efforts reported in the literature, A-primed uses concurrent engineering and information automation technologies to enhance information transfer. A unique aspect of our approach to agility is the qualification during development of a family of related product designs and their production processes, rather than a single design and its attendant processes. Applying engineering principles and statistical design of experiments, economies of test and analytic effort are realized for the qualification of the device family as a whole. Thus the need is minimized for test and analysis to qualify future devices from this family, thereby further reducing the design-to-production cycle time. As a measure of the success of the A-primed approach, the first design took 24 days to produce, and operated correctly on the first attempt. A flow diagram for the qualification process is presented. Guidelines are given for implementation, based on the authors experiences as members of the A-primed qualification team.

A method has been formulated and tested to provide laser weld schedules using a mathematical model and parameter optimization. This effort, on behalf of the Smartweld manufacturing initiative, seeks to provide: (1) laser power, (2) part travel speed, and (3) lens focal length to optimize weld process efficiency while constraining weld dimensions. Experimental data for three metals was fit to provide the mathematical model. Embedded material constants in the computational model allowed the extension to seven metals. A genetic algorithm, was used to accomplish the optimization. Lens focal length is a discrete variable and necessitated this type of algorithm. All coding was done in MATLAB and a graphical user interface was provided. Contour and surface plots, available through the interface, provide the analyst with insight as to optimum welds which are reachable within the problem-specified bounds on power, speed, and available focal lengths.

This paper is a presentation made in support of the statistics profession. This field can say it has had a major impact in most major fields of study presently undertaken by man, yet it is not perceived as an important, or critical field of study. It is not a growth field either, witness the almost level number of faculty and new PhD`s produced over the past twenty years. The author argues the profession must do a better job of selling itself to the students it educates. Awaken them to the impact of statistics in their lives and their business worlds, so that they see beyond the formulae to the application of these principles.

The System Surety Assessment Department 12332 of Sandia National Laboratories performed an independent nuclear safety assessment of the Non-nuclear Verification Instrument NNV-470AS. The NNV-470AS was assessed for structural integrity, characteristics of its electrical circuits, and its Radiated Electrical Emissions. Department 12332 concluded that the NNV-470AS and its Operational Procedures are safe to use with war reserve weapons. However, strict adherence to the Operational Procedures for the NNV-470AS is needed to prevent tampering with the instrument.

This document is a compilation of the Field Work Proposals (FWP) for the DOE BES Materials Sciences Program. The program is directed toward Scientifically Tailored Materials, specifically for energy applications.

MACCS was developed at Sandia National Laboratories (SNL) under U.S. Nuclear Regulatory Commission (NRC) sponsorship to estimate the offsite consequences of potential severe accidents at nuclear power plants (NPPs). MACCS was publicly released in 1990. MACCS was developed to support the NRC`s probabilistic safety assessment (PSA) efforts. PSA techniques can provide a measure of the risk of reactor operation. PSAs are generally divided into three levels. Level one efforts identify potential plant damage states that lead to core damage and the associated probabilities, level two models damage progression and containment strength for establishing fission-product release categories, and level three efforts evaluate potential off-site consequences of radiological releases and the probabilities associated with the consequences. MACCS was designed as a tool for level three PSA analysis. MACCS performs probabilistic health and economic consequence assessments of hypothetical accidental releases of radioactive material from NPPs. MACCS includes models for atmospheric dispersion and transport, wet and dry deposition, the probabilistic treatment of meteorology, environmental transfer, countermeasure strategies, dosimetry, health effects, and economic impacts. The computer systems MACCS is designed to run on are the 386/486 PC, VAX/VMS, E3M RISC S/6000, Sun SPARC, and Cray UNICOS. This paper provides an overview of MACCS, reviews some of the applications of MACCS, international collaborations which have involved MACCS, current developmental efforts, and future directions.

We present three codes for the Intel Paragon that address the problem of three-dimensional seismic imaging of complex geologies. The first code models acoustic wave propagation and can be used to generate data sets to calibrate and validate seismic imaging codes. This code reported the fastest timings for acoustic wave propagation codes at a recent SEG (Society of Exploration Geophysicists) meeting. The second code implements a Kirchhoff method for pre-stack depth migration. Development of this code is almost complete, and preliminary results are presented. The third code implements a wave equation approach to seismic migration and is a Paragon implementation of a code from the ARCO Seismic Benchmark Suite.

We have developed a new intracavity laser technique that uses a living or a fixed cell as an integral component of the laser. The cells are placed on an AlGaAs/GaAs surface-emitting semiconductor wafer and covered with a glass dielectric mirror to form a laser resonator. In this arrangement, the cells serve as optical waveguides (or lens elements) to confine (or focus) light generated in the resonator by the semiconductor. Because of the high transparency, the cells aid the lasing process to generate laser light. This ultra sensitive laser provides a novel imaging/spectroscopic technique for histologic examination which we demonstrate with normal and sickled human red blood cells. Extremely high contrast microscopic images of the cells are observed near 830-850 nm. These images correspond to electromagnetic modes of cell structures and are sensitive to shape of the cell. Using a high resolution spectrometer, we resolve the light emitted from these images into very narrow spectral peaks associated with the lasing modes. Analysis of the spectra reveals that the distribution of peaks is quite different for normal and sickled red blood cells. This technique, in a more developed form, may be useful for the rapid analysis of other kinds of normal and abnormal cells.

In 1992, a sinkhole was discovered above a Strategic Petroleum Reserve storage facility at Weeks Island, Louisiana. The oil is stored in an old salt mine located within a salt dome. In order to assess the hydrologic significance of the sink hole, an In Situ Permeable Flow Sensor was deployed within a sand-filled conduit in the salt dome directly beneath the sinkhole. The flow sensor is a recently developed instrument which uses a thermal perturbation technique to measure the magnitude and direction of the full 3-dimensional groundwater flow velocity vector in saturated, permeable materials. The flow sensor measured substantial groundwater flow directed vertically downward into the salt dome. The data obtained with the flow sensor provided critical evidence which was instrumental in assessing the significance of the sinkhole in terms of the integrity of the oil storage facility.

The World Wide Web provides a unified method of access to various information services on the Internet via a variety of protocols. Mosaic and other browsers give users a graphical interface to the Web that is easier to use and more visually pleasing than any other common Internet information service today. The availability of information via the Web and the number of users accessing it have both grown rapidly in the last year. The interest and investment of commercial firms in this technology suggest that in the near future, access to the Web may become as necessary to doing business as a telephone. This is problematical for organizations that use firewalls to protect their internal networks from the Internet. Allowing all the protocols and types of information found in the Web to pass their firewall will certainly increase the risk of attack by hackers on the Internet. But not allowing access to the Web could be even more dangerous, as frustrated users of the internal network are either unable to do their jobs, or find creative new ways to get around the firewall. The solution to this dilemma adopted at Sandia National Laboratories is described. Discussion also covers risks of accessing the Web, design alternatives considered, and trade-offs used to find the proper balance between access and protection.

Sandia is a multiprogram engineering and science laboratory operated for the Department of Energy with major facilities at Albuquerque, New Mexico, and Livermore, California, and a test range near Tonapah, Nevada. It has major research and development responsibilities for nuclear weapons, arms control, energy, the environment, economic competitiveness, and other areas of importance to the needs of the nation. The principal mission is to support national defense policies by ensuring that the nuclear weapon stockpile meets the highest standards of safety, reliability, security, use control, and military performance. This publication gives a brief overview of the multifaceted research programs conducted by the laboratory.

The SANdia total-DOSe Estimator (SANDOSE) is used to estimate total radiation dose to a (BRL-CAT) solid model, SANDOSE uses the mass-sectoring technique to sample the model using ray-tracing techniques. The code is integrated directly into the BRL-CAD solid model editor and is operated using a simple graphical user interface. Several diagnostic tools are available to allow the user to analyze the results. Based on limited validation using several benchmark problems, results can be expected to fall between a 10% underestimate and a factor of 2 overestimate of the actual dose predicted by rigorous radiation transport techniques. However, other situations may be encountered where the results might fall outside of this range. The code is written in C and uses X-windows graphics. It presently runs on SUN SPARCstations, but in theory could be ported to any workstation with a C compiler and X-windows. SANDOSE is available via license by contacting either the Sandia National Laboratories Technology Transfer Center or the author.

The Environmental Restoration (ER) Project at Sandia National Laboratories, New Mexico is managing the project to assess and, when necessary, to remediate sites contaminated by the lab operations. Within the ER project, the site-wide hydrogeologic characterization task is responsible for the area-wide hydrogeologic investigation. The purpose of this task is to reduce the uncertainty about the rate and direction of groundwater flow beneath the area and across its boundaries. This specific report deals with the installation of PGS-1 monitoring well which provides information on the lithology and hydrology of the aquifer in the northern area of the Kirtland Air Force Base. The report provides information on the well design; surface geology; stratigraphy; structure; drilling, completion, and development techniques; and borehole geophysics information.

This assessment studied the performance of high-level radioactive waste and spent nuclear fuel in a hypothetical repository in unsaturated tuff. The results of this 10-month study are intended to help guide the Office of Environment Management of the US Department of Energy (DOE) on how to prepare its wastes for eventual permanent disposal. The waste forms comprised spent fuel and high-level waste currently stored at the Idaho National Engineering Laboratory (INEL) and the Hanford reservation. About 700 metric tons heavy metal (MTHM) of the waste under study is stored at INEL, including graphite spent nuclear fuel, highly enriched uranium spent fuel, low enriched uranium spent fuel, and calcined high-level waste. About 2100 MTHM of weapons production fuel, currently stored on the Hanford reservation, was also included. The behavior of the waste was analyzed by waste form and also as a group of waste forms in the hypothetical tuff repository. When the waste forms were studied together, the repository was assumed also to contain about 9200 MTHM high-level waste in borosilicate glass from three DOE sites. The addition of the borosilicate glass, which has already been proposed as a final waste form, brought the total to about 12,000 MTHM.

A remediation of a gas cylinder disposal pit at Sandia National Laboratories, New Mexico has recently been completed. The cleanup prevented possible spontaneous releases of hazardous gases from corroded cylinders that may have affected nearby active test areas at Sandia`s Technical Area III. Special waste management, safety, and quality plans were developed and strictly implemented for this project. The project was conceived from a waste management perspective, and waste minimization and management were built into the planning and implementation phases. The site layout was planned to accommodate light and heavy equipment, storage of large quantities of suspect soil, and special areas to stage and treat gases and reactive chemicals removed from the pit, as well as radiation protection areas. Excavation was a tightly controlled activity using experienced gas cylinder and reactive chemical specialists. Hazardous operations were conducted at night under lights, to allow nearby daytime operations to function unhindered. The quality assurance plan provided specific control of, and documentation for, critical decisions, as well as the record of daily operations. Both hand and heavy equipment excavation techniques were utilized. Hand excavation techniques were utilized. Hand excavation techniques allows sealed glass containers to be exhumed unharmed. In the end, several dozen thermal batteries; 5 pounds (2.3 kg) of lithium metal; 6.6 pounds (3.0 kg) of rubidium metal; several kilograms of unknown chemicals; 140 cubic yards (107 cubic meters) of thorium-contaminated soil; 270 cubic yards (205 cubic meters) of chromium-contaminated soil; and 450 gas cylinders, including 97 intact cylinders containing inert, flammable, toxic, corrosive, or oxidizing gases were removed and effectively managed to minimize waste.

Lithium ion systems, although relatively new, have attracted much interest worldwide. Their high energy density, long cycle life and relative safety, compared with metallic lithium rechargeable systems, make them prime candidates for powering portable electronic equipment. Although lithium ion cells are presently used in a few consumer devices, e.g., portable phones, camcorders, and laptop computers, there is room for considerable improvement in their performance. Specific areas that need to be addressed include: (1) carbon anode--increase reversible capacity, and minimize passivation; (2) cathode--extend cycle life, improve rate capability, and increase capacity. There are several programs ongoing at Sandia National Laboratories which are investigating means of achieving the stated objectives in these specific areas. This paper will review these programs.

The System Surety Assessment Department 12332 of Sandia National Laboratories performed an independent nuclear safety assessment of the Non-nuclear Verification Instrument T562. The T562 was assessed for structural integrity, characteristics of its electrical circuits, and its Radiated Electrical Emissions. Department 12332 concluded that the T562 and its Operational Procedures are safe to use with war reserve weapons. However, strict adherence to the Operational Procedures for the T562 is needed to prevent tampering with the instrument.

This report is a basic data report for field operations associated with the drilling, logging, completion, and development of Tijeras Arroyo well TJA-2. This test/monitoring well was installed as part of Sandia National Laboratories, New Mexico, Environmental Restoration Project.

We have demonstrated for the first time high frequency (210 MHz) oxide breakdown at the wafer-level using on-chip, self-stressing test structures. This is the highest frequency oxide breakdown that has been reported. We used these structures to characterize the variation in oxide breakdown with frequency (from 1 Hz to over 200 MHz) and duty cycle (from 10% to 90%). Since the stress frequency, duty cycle and temperature are controlled by DC signals in these structures, we used conventional DC wafer-level equipment without any special modifications (such as high frequency cabling). This self-stressing structure significantly reduces the cost of performing realistic high frequency oxide breakdown experiments necessary for developing reliability models and building-in-reliability.

Dextor`s Hysol EA-9394 is a room temperature curable paste adhesive representative of the adhesives used in wind turbine blade joints. A mechanical testing program has been performed to characterize this adhesive. Tension, compression stress relaxation, flexural, butt tensile, and fracture toughness test results are reported.

Advances of computer hardware and communication software have made it possible to perform parallel-processing computing on a collection of desktop workstations. For many applications, multitasking on a cluster of high-performance workstations has achieved performance comparable or better than that on a traditional supercomputer. From the point of view of cost-effectiveness, it also allows users to exploit available but unused computational resources, and thus achieve a higher performance-to-cost ratio. Monte Carlo calculations are inherently parallelizable because the individual particle trajectories can be generated independently with minimum need for interprocessor communication. Furthermore, the number of particle histories that can be generated in a given amount of wall-clock time is nearly proportional to the number of processors in the cluster. This is an important fact because the inherent statistical uncertainty in any Monte Carlo result decreases as the number of histories increases. For these reasons, researchers have expended considerable effort to take advantage of different parallel architectures for a variety of Monte Carlo radiation transport codes, often with excellent results. The initial interest in this work was sparked by the multitasking capability of MCNP on a cluster of workstations using the Parallel Virtual Machine (PVM) software. On a 16-machine IBM RS/6000 cluster, it has been demonstrated that MCNP runs ten times as fast as on a single-processor CRAY YMP. In this paper, we summarize the implementation of a similar multitasking capability for the coupled electron/photon transport code system, the Integrated TIGER Series (ITS), and the evaluation of two load balancing schemes for homogeneous and heterogeneous networks.

The transportation risk analysis code, RADTRAN 4, computer estimates of incident-free dose consequence and accident dose-risk. The output of the code includes a tabulation of sensitivity of the result to variation of the input parameters for the incident-free analysis. The values are calculated using closed mathematical expressions derived from the constitutive equations, which are linear. However, the equations for accident risk are not linear, in general, and a similar tabulation has not been available. Because of the importance of knowing how accident-risk estimates are affected by uncertainties in the input parameters, a direct investigation was undertaken of the variation in calculated accident dose-risk with changes in individual parameters. A limited, representative group of transportation scenarios was used, initially, to determine which of 23 accident-risk parameters affect the calculated accident dose risk significantly. Many of the parameters were observed to have minimal effect on the output, and others were judged as ``fixed`` either by regulation, convention or standards. The remaining 5 variables were selected for further study through Latin Hypercube Sampling (LHS). LHS yields statistical information from observations (risk calculations) resulting from multiple input-parameter sets compiled from ``random`` sampling of parameter distributions. The LHS method requires fewer observations than classical Monte Carlo methods to yield statistically significant results. This paper presents the preliminary parameter study and LHS application results together with further LHS evaluations of RADTRAN input parameters.

This document contains information about the research and development programs dealing with waste transport at Sandia National Laboratories. This paper discusses topics such as: Why new packaging is needed; analytical methodologies and design codes;evaluation of packaging components; materials characterization; creative packaging concepts; packaging engineering and analysis; testing; and certification support.

In 1993, the mirror facets of one of Sandia`s point-focusing solar collectors, the Test Bed Concentrator {number_sign}2 (TBC-2), were reconditioned. The concentrator`s optical performance was evaluated before and after this operation. This report summarizes and compares the results of these tests. The tests demonstrated that the concentrator`s total power and peak flux were increased while the overall flux distribution in the focal plane remained qualitatively the same.

Computational physicists at Sandia National Laboratories have moved the Eulerian CTH code, and the arbitrary-Lagrangian-Eulerian ALEGRA code to distributed memory parallel computers. CTH is a three-dimensional solid mechanics code used for large-deformation, shock wave analysis. ALEGRA is a three-dimensional arbitrary Lagrangian-Eulerian solid-mechanics code used for coupled large-deformation, shock and structural mechanics problems. This paper discusses our experiences moving the codes to parallel computers, the algorithms we used and our experiences running the codes.

The report presents an evaluation of worldwide research efforts in three specific renewable energy technologies, with a view towards future United States (US) energy security, environmental factors, and industrial competitiveness. The overall energy technology priorities of foreign governments and industry leaders, as well as the motivating factors for these priorities, are identified and evaluated from both technological and policy perspectives. The specific technologies of interest are wind, solar thermal, and solar photovoltaics (PV). These program areas, as well as the overall energy policies of Denmark, France, Germany, Italy, the United Kingdom (UK), Japan, Russia, and the European Community as a whole are described. The present and likely future picture for worldwide technological leadership in these technologies-is portrayed. The report is meant to help in forecasting challenges to US preeminence in the various technology areas, particularly over the next ten years, and to help guide US policy-makers as they try to identify specific actions which would help to retain and/or expand the US leadership position.

The Advanced Geophysical Technology Department (6114) and the Telemetry Technology Development Department (2664) have, in conjunction with the Oil Recovery Technology Partnership, developed a Multi-Level Seismic Receiver (MLSR) for use in crosswell seismic surveys. The MLSR was designed and evaluated with the significant support of many industry partners in the oil exploration industry. The unit was designed to record and process superior quality seismic data operating in severe borehole environments, including high temperature (up to 200{degrees}C) and static pressure (10,000 psi). This development has utilized state-of-the-art technology in transducers, data acquisition, and real-time data communication and data processing. The mechanical design of the receiver has been carefully modeled and evaluated to insure excellent signal coupling into the receiver.

This document describes the results of the Workshop on Port Selection Criteria for Shipments of Spent Nuclear Fuel. The workshop was held at the United States Merchant Marine Academy in Kings Point, New York on November 15 and 16, 1993. The workshop panel of maritime experts developed criteria for the US Department of Energy for the evaluation and selection of ports of entry for spent-fuel shipments. While recommending criteria for selecting ports, the workshop panel agreed that any port capable of handling an ocean-going vessel is capable of safely receiving spent nuclear fuel.

A comprehensive three-dimensional numerical investigation of the effect of beat source travel speed on temperatures and resulting thermal stresses was performed for CO{sub 2}-laser welding. The test specimen was a small thermal battery header containing several stress-sensitive glass-to-metal seals surrounding the electrical connections and a temperature sensitive ignitor located under the header near the center. Predictions of the thermal stresses and temperatures in the battery header were made for several travel speeds of the laser. The travel speeds examined ranged from 10mm/sec to 50mm/sec. The results indicate that faster weld speeds result in lower temperatures and stresses for the same size weld. This is because the higher speed welds are more efficient, requiring less energy to produce a given weld. Less energy absorbed by the workpiece results in lower temperatures, which results in lower stresses.

Electrochemically formed porous silicon (PS) was reported in 1991 to exhibit visible photoluminescence. This discovery could lead to the use of integrated silicon-based optoelectronic devices. This LDRD addressed two general goals for optical emission from Si: (1) investigate the mechanisms responsible for light emission, and (2) tailor the microstructure and composition of the Si to obtain photoemission suitable for working devices. PS formation, composition, morphology, and microstructure have been under investigation at Sandia for the past ten years for applications in silicon-on-insulator microelectronics, micromachining, and chemical sensors. The authors used this expertise to form luminescent PS at a variety of wavelengths and have used analytical techniques such as in situ Raman and X-ray reflectivity to investigate the luminescence mechanism and quantify the properties of the porous silicon layer. Further, their experience with ion implantation in Si lead to an investigation into alternate methods of producing Si nanostructures that visibly luminesce.

The present study offers new data and analysis on the transient shock strength and equation-of-state properties of ceramics. Various dynamic data on nine high strength ceramics are provided with wave profile measurements, through velocity interferometry techniques, the principal observable. Compressive failure in the shock wave front, with emphasis on brittle versus ductile mechanisms of deformation, is examined in some detail. Extensive spall strength data are provided and related to the theoretical spall strength, and to energy-based theories of the spall process. Failure waves, as a mechanism of deformation in the transient shock process, are examined. Strength and equation-of-state analysis of shock data on silicon carbide, boron carbide, tungsten carbide, silicon dioxide and aluminum nitride is presented with particular emphasis on phase transition properties for the latter two. Wave profile measurements on selected ceramics are investigated for evidence of rate sensitive elastic precursor decay in the shock front failure process.

Under a cooperative research and development agreement with General Motors Corporation, lead-free solder systems including the flux, metallization, and solder are being developed for high temperature, underhood applications. Six tin-rich solders, five silver-rich metallizations, and four fluxes were screened using an experimental matrix whereby every combination was used to make sessile drops via hot plate or Heller oven processing. The contact angle, sessile drop appearance, and in some instances the microstructure was evaluated to determine combinations that would yield contact angles of less than 30{degrees}, well-formed sessile drops, and fine, uniform microstructures. Four solders, one metallization, and one flux were selected and will be used for further aging and mechanical property studies.

Sandia National Laboratories is one of the Department of Energy`s primary research and development laboratories. Our essential mission is to support the national interests of the US in defense, energy, and the environment. Managed by Martin Marietta Corporation for DOE, Sandia focuses its resources on problems of national interest that require the integration of science and technology for their solution. We all hope that this period of sweeping alterations in international affairs will result in a successful transition from the Cold War to a period of sustainable global security and prosperity. In the meantime, our nation`s interests are best served by continued commitment to Sandia`s traditional responsibilities. Nonetheless, as momentous developments are reshaping the world, Sandia is also changing from its beginning as a closed operation concentrating on classified defense programs, Sandia has become a more accessible resource that focuses on research and development partnerships with industry and universities as a way to ensure continued success in DOE`s evolving core mission area of nuclear weapons, energy, environment, and the basis sciences. Through these collaborative efforts, Sandia and its partners are also benefiting the economic competitiveness of our nation. Sandia places a special emphasis on working with small businesses as both technology transfer partners and suppliers of goods and services. We are also reaching out the the larger community surrounding Sandia, striving to provide technological solution and accurate information to meet community needs. We believe that the dialogue we are creating will benefit Sandia, the community, and the nation. Our goal is to render `` exceptional service in the national interest`` by returning maximum value on the investment in the labs. As you review this document, look for new ways in which Sandia can contribute to the solution of problems facing our nation.

The US Department of Energy (DOE) is preparing to request the US Environmental Protection Agency to certify compliance with the radioactive waste disposal standards found in 40 CFR Part 191 for the Waste Isolation Pilot Plant (WIPP). The DOE will also need to demonstrate compliance with a number of other State and Federal standards and, in particular, the Land Disposal Restrictions of the Resource Conservation and Recovery Act (RCRA), 40 CFR Part 268. Demonstrating compliance with these regulations requires an assessment of the long-term performance of the WIPP disposal system. Re-evaluation and extension of past scenario development for the WIPP forms an integral part of the ongoing performance assessment (PA) process.

Radiation in participating media is an important transport mechanism in many physical systems. The simulation of complex radiative transfer has not effectively exploited high-performance computing capabilities. In response to this need, a workshop attended by members active in the high-performance computing community, members active in the radiative transfer community, and members from closely related fields was held to identify how high-performance computing can be used effectively to solve the transport equation and advance the state-of-the-art in simulating radiative heat transfer. This workshop was held on March 29-30, 1994 in Albuquerque, New Mexico and was conducted by Sandia National Laboratories. The objectives of this workshop were to provide a vehicle to stimulate interest and new research directions within the two communities to exploit the advantages of high-performance computing for solving complex radiative heat transfer problems that are otherwise intractable.

Perimeter intrusion detection systems are an integral part of most physical security systems. Sandia National Laboratories, under the sponsorship of the U.S. Department of Energy, Office of Safeguards and Security; the U.S. Military Services; and many other U.S. Government Agencies, has over the last 20 years conducted surveys of available perimeter intrusion detection sensors and has tested many of the sensors manufactured in the United States and other countries. An overview of the newer and more advanced technologies employed in these sensors is provided.

A general adjoint coupled electron-photon Monte Carlo code for solving the Boltzmann-Fokker-Planck equation has recently been created. It is a modified version of ITS 3.0, a coupled electron-photon Monte Carlo code that has worldwide distribution. The applicability of the new code to radiation-interaction problems of the type found in space environments is demonstrated. © 1995 IEEE

Several studies have shown that the surface morphology can be smoother during simultaneous ion bombardment and growth than during growth alone, however, the atomistic mechanism responsible for the smoothing effect has been difficult to determine. We have developed Monte Carlo simulations of growth and defect diffusion to model the interaction between growth atoms and ion-induced defects and to present a simple atomistic mechanism that describes the effects of low-energy ion bombardment during ion-assisted growth of germanium. Measurements of ion-induced point defect production indicate that a large number of defects exist only temporarily on the surface at typical growth temperatures, because the defects have sufficient mobility to recombine and annihilate. We propose that this ion-induced transient defect population plays a significant role in modifying the dynamic surface morphology. The simulations support a surface smoothing mechanism that involves the destabilization of adatom islands by the transient ion-induced defects. The optimum simulated steady-state surface morphology can be achieved with ion-induced defect production rates less than or equal to 10 defects/ion. We find that low-energy ion bombardment during growth effectively lowers the temperature at which step-flow growth can be achieved.

We have characterized the optical properties of heteroepitaxial Si1-xCx and Si0.924-xGe0.076Cx (0≤x≤0.014) alloys grown on Si substrates by solid phase epitaxy using spectroscopic ellipsometry. The measured dielectric function confirms that the samples are of good crystalline quality. We determined the E1 and E2 band gaps by lineshape-fitting the features in the second derivative spectra of the dielectric functions. Also, we discuss the shift of the band gaps with C concentration arising from strain and chemical alloying.

Inferring phylogenetic trees is a fundamental problem in computational-biology. We present a new objective criterion, the phylogenetic number, for evaluating evolutionary trees for species defined by biomolecular sequences or other qualitative characters. The phylogenetic number of a tree T is the maximum number of times that any given character state arises in T. By contrast, the classical parsimonycriterion measures the total number of times that different character states arise in T. We consider the following related problems: finding the tree with minimum phylogenetic number, and computing the phylogenetic number of a given topology in which only the leaves are labeled by species. When the number of states is bounded (as is the case for biomolecular sequence characters), we can solve the second problem in polynomial time. We can also compute a fixed-topology 2-phylogeny (when one exists) for an arbitrary number of states. This algorithm can be used to further distinguish trees that are equal under parsimony. We also consider a number of other related problems.

The NASA Standard Detonator (NSD) is employed in support of a number of current applications, including the Space Shuttle. This effort was directed towards providing test results to characterize the output of this device for its use in a safe and arm device. As part of the investigation, flash X-ray was used to provide stop-motion photographs of the flying metal plate that is created by initiation of the detonator. This provided researchers with a better understanding of the shape and character of the high- velocity disk as it propagated across the gap between the detonator and next assembly. The second portion of the study used a velocity interferometer to evaluate the acceleration and velocity histories of the flying plate, providing a quantified assessment of the detonator’s ability to initiate the explosive in the next explosive.

For many years, explosive components have used hotwires to convert an electrical stimulus into the thermal energy required to initiate the device. A Semi-conductor Bridge (SCB) performs the same function, but with the advantage of requiring approximately 1/10 the input energy of a comparable hotwire, while retaining excellent no-fire characteristics. The SCB also demonstrates faster function times due to its inherently-lower thermal mass. This paper discusses the development and production of two SCB-based devices, the MC4491 Initiator and the MC4492 Actuator. The initiator is designed to shock initiate a linear shaped charge by accelerating a thin metal plate across a small gap. The actuator functions several different components, sewing as either an actuator by producing a rapidly expanding gas to activate piston mechanisms or as an ignitor by providing hot particles for initiating pyrotechnic mixtures. Details are provided on the construction of both devices, methods of assembly, and performance characteristics (function time, flyer velocity, pressure in a closed bomb, heat content, and no-fire and all-fire levels).

The Segmented Rail Phased Induction Motor (SERAPHIM) is a compact, pulsed linear induction motor (LIM) offering a unique capability for very high speed train propulsion. It uses technology developed for the Sandia coilgun, an electromagnetic launcher designed to accelerate projectiles to several kilometers per second! Both aluminum cylinders and plates were accelerated to a kilometer per second (Mach 3) by passing through a sequence of coils which were energized at the appropriate time. Although this technology was developed for ultra-high velocity, it can be readily adapted to train propulsion for which, at sea level, the power required to overcome air resistance limits the operational speed to a more modest 300 mph. Here, the geometry is reversed. The coils are on the vehicle and the "projectiles" are fixed along the roadbed. In the 1970's, the Federal Railroad Administration tested a 200 mph train riding on passive wheels and powered by a conventional LIM. In a LIM, electrical windings generate a backward moving wave of magnetic flux in a conducting reaction rail, producing a forward force. SERAPHIM operates not by embedding flux in a conductor, but by excluding it. In this propulsion scheme, pairs of closely spaced coils on the vehicle straddle a segmented aluminum reaction rail. A high frequency current is switched on as a coil pair crosses an edge and remains off as they overtake the next segment. This induces surface currents which repel the coil. In essence, the pulsed coils push off segment edges because at the high frequency of operation, the flux has insufficient time to penetrate. In contrast to conventional LIMs, the performance actually improves with velocity, even for a minimal motor consisting of a single coil pair reacting with a single plate. With either distributed onboard power, a passive wheeled train powered by a SERAPHIM is an attractive alternative to one which is levitated using superconducting magnets (MAGLEV) and propelled by switched electrified coils in the roadbed. This paper will present results of proof-of-principle tests, electromagnetic computer simulations, and systems analysis. It is concluded that this new linear induction motor can be implemented using existing technology and is a promising alternative propulsion method for very high speed rail transportation. © Copyright 1995 Society of Automotive Engineers, Inc.

We present a motion planner for multiple moving objects in two dimensions. The search for collision-free paths is performed in the composite configuration space of all the moving objects to guarantee a solution, and the efficiency of our planner is demonstrated with examples. Our motion planner can be characterized with a hierarchical, multi-resolution search of the configuration space along with a generate-and-test paradigm for solution paths. Because of the high dimensionality of the composite configuration space, our planner is most useful for cases with a small number of moving objects. Some of the potential applications are navigation of several mobile robots, and planning part motions for a multi-handed assembly operation.

There have been numerous research efforts in the field of motion planning, resulting in many theoretical and practical results. We review the current status of existing motion planning algorithms, evaluate their completenesses and efficiencies on modern computers, and suggest fruitful future research directions.

The semiconductor bridge, SCB, developed by Sandia National Laboratories is a maturing technology now being used in several applications by Sandia customers. Most applications arose because of a need at the system level to provide explosive assemblies that were light weight, small volume, low cost and required small quantities of electrical energy to function — for the purposes of this paper we define an explosive assembly to mean the combination of the firing set and an explosive component. As a result, and because conventional firing systems could not meet the stringent size, weight and energy requirements of our customers, we designed and are investigating SCB applications that range from devices for Sandia applications to igniters for fireworks. We present in this paper an overview of SCB technology with specific examples of the systems designed for our customers to meet modern requirements that sophisticated explosive systems must satisfy in today’s market environments.

HICUP models the angular dependent heavy ion upset cross section. It pulls together many of the parameters and concepts used to characterize the Single Event Upset (SEU) phenomena, unifying them in a single cohesive model. HICUP is based on a Rectangular Parallelepiped (RPP) geometry for the sensitive volume and the Weibull density function for the upset threshold energy. Excellent agreement is obtained between the model and heavy ion test data. HICUP is used to derive the correct scaling laws for transforming angular cross section data to normal incidence, reconciling two previously proposed inverse cosine scaling corrections. The angle-integrated HICUP model, I-HICUP, is used in Galactic Cosmic Ray (GCR) upset rate calculations with results nearly identical to the Space Radiation• code. Letaw [12] has procuced an automated SEU parameter fitting routine based on HICUP and the cH2 method. It ferrets out the best-fit critical SEU parameters embedded within the raw angular test data, including charge collection depth and funnel length. His method couples directly to the upset rate calculation in a self-consistent manner eliminating the need to arbitrarily assume a device depth. Results of this new procedure are presented. © 1995 IEEE

A sinkhole was observed over the edge of the two-level former salt mine that was converted for oil storage. Diagnostic studies suggest a direct connection exists between the surface collapse area and the underground mine as shown by correlative measurements of sediment slump rates and probable brine influx into the mine. The dissolution of salt below the sinkhole that initiated the leak into the mine was likely caused by several confluent geologic processes, and exacerbated by mining-induced stresses that created fractures which served as hydrologic flowpaths. Modelling studies of mine stresses show that years may be required before tensional cracking begins to occur, but once begun can continue to develop, and relieve the stress in that specific regime. The crack regime creates the avenue for incursion of groundwater. Mitigation measures include increasing the mine pressure, slowing the dissolution by injecting brine into the sinkhole throat, and construction of a freeze curtain to restrict hydrologic flowpaths. -from Authors

A general method for applying command shaping to various multiple degree of freedom cranes is described such that the payload moves to a specified point without residual oscillation. A dynamic programming is used for general command shaping for optimal maneuvers. The results taken are compared to near-optimal solutions where the commands are linear combinations of accelerations pulse basis functions. Simulation results and experimental verification for a variable load-line length rotary crane are also presented using design procedures.

The issues of verification, calibration, and validation of computational fluid dynamics (CFD) codes has been receiving increasing levels of attention in the research literature and in engineering technology. Both CFD researchers and users of CFD codes are asking more critical and detailed questions concerning the accuracy, range of applicability, reliability and robustness of CFD codes and their predictions. This is a welcomed trend because it demonstrates that CFD is maturing from a research tool to the world of impacting engineering hardware and system design. In this environment, the broad issue of code quality assurance becomes paramount, However, the philosophy and methodology of building confidence in CFD code predictions has proven to be more difficult than many expected. A wide variety of physical modeling errors and discretization errors are discussed. Here, discretization errors refer to all errors caused by conversion of the original partial differential equations to algebraic equations, and their solution. Boundary conditions for both the partial differential equations and the discretized equations will be discussed. Contrasts are drawn between the assumptions and actual use numerical method consistency and stability. Commen are also made concerning the existence and uniqueness solutions for both the partial differential equations and the discrete equations. Various techniques are suggested for the detection and estimation of errors caused by physical modeling and discretization of the partial differential equations.

Carbon Nitride (CNx) films have been grown by ion-assisted pulsed-laser deposition (IAPLD). Graphite targets were laser ablated while bombarding the substrate with ions from a broad-beam Kaufman-type ion source. The ion voltage, current density, substrate temperature, and feed gas composition (N2 in Ar) have been varied. The resultant films were characterized by Raman, Fourier transform infrared (FTIR), and Rutherford back scattering (RBS) spectroscopy. Samples with ≈30% N/C ratio have been fabricated. The corresponding Raman and FTIR spectra indicate that nitrogen is incorporated into the samples by insertion into sp2- bonded structure. A low level of C≡N triple bonds is also found. As the ion current and voltage are increased with a pure Ar ion beam, Raman peaks associated with nanocrystalline graphite appear in the spectra. Adding low levels of nitrogen to the ion beam first reduces the Raman intensity in the vicinity of the graphite disorder peak without adding detectable amounts of nitrogen to the films (as measured by RBS). At higher nitrogen levels in the ion beam, significant amounts of nitrogen are incorporated into the samples, and the magnitude of the ″disorder″ peak increases. By increasing the temperature of the substrate during deposition, the broad peak due mainly to sp2-bonded C-N in the FTIR spectra is shifted to lower wavenumber. This could be interpreted as evidence of single-bonded C-N; however, it is more likely that the character of the sp2 bonding is changing.

Extensive surface pressure measurements were obtained on a hypersonic vehicle configuration at Mach 8. All of the experimental results were obtained in the Sandia National Laboratories Mach 8 hypersonic wind tunnel for lamipar boundary layer conditions. The basic vehicle configuration IS a spherically blunted 100 half-angle cone with a slice parallel with the axis of the vehicle. The bluntness ratio of the geometly IS 10% and the slice begins at 70% of the length of the vehicle. Surface pressure measurements were obtained for angles of attack from -10 to +180. for various roll angles, at 96 locations on the body surface. A new and innovative uncertainty analysis was devised to estimate the contributors to surface pressure meaSment uncenainty. Quantitative estimates were computed for the uncertainty contributions due to the complete insmmentation system, nonunifoxmity of flow in the test section of the wind Nnnel. and variations in the wind tunnel model. This extensive set of high-quality surface pressure measurements is recommended for use in the calibration and validation of computational fluid dynamics codes for hyuersonic flow conditions.

Short-pulse accelerator technology developed during the early 1960's through the late 1980's is being extended to high average power systems capable of use in industrial and environmental applications. Processes requiring high dose levels and/or high volume throughput will require systems with beam power levels from several hundreds of kilowatts to megawatts. Beam accelerating potentials can range from less than 1 MeV to as much as 10 MeV depending on the type of beam, depth of penetration required, and the density of the product being treated. This paper addresses the present status of a family of high average power systems, with output beam power levels up to 200 kW, now in operation that use saturable core switches to achieve output pulse widths of 50 to 80 nanoseconds. Inductive adders and field emission cathodes are used to generate beams of electrons or x-rays at up to 2.5 MeV over areas of 1000 cm2. Similar high average power technology is being used at ≤ 1 MeV to drive repetitive ion beam sources for treatment of material surfaces over 100's of cm2. © 1995.

Performance of an electromagnetic induction launcher is considered for three types of armatures. These are: solid, 1-element wound and 16-element wound aluminum armatures. The one element wound armature has uniform current density throughout and thus can withstand field reversal (working against embedded armature flux) and still maintain low temperature. Slingshot simulations were performed for several configurations. Best performance was obtained for a single element wound armature with two field reversals. For a 60 kg projectile, 10.5 cm coil inner radius and 5.5 cm coil build, the velocity after 50 meters of launcher length (670 stages) exceeded 3.5 km/sec with an overall efficiency of about 45%. For the same parameters the solid and 16-element wound armatures reach a velocity of about 3.3 km/sec after 800 stages (60 meters of launcher length) but without field reversal. A velocity of 3.5 km/sec is possible after 60 meters of launcher length with the 16-element wound armature with one field reversal, but the temperature is close to the melting temperature of aluminum. In all simulations with a solid armature, melting of some of the surface material occurs. However, it is shown that most of the melting occurs after contribution has been made to the forward going pressure, that is, melting does not affect the electrical performance of the launcher. The effect of coil firing time jitter on launcher performance is also considered and is found to be very small for realistic perturbations. For ± 2 μ–secs random jitter, the reduction in the final velocity for a 60 meter launcher with a solid armature is less than 0.1% and the increase in temperature is only 2%. This holds for all types of armatures. © 1995 IEEE

Cold filling refers to flowing a fluid through piping or tubes that are at temperatures below the fluid’s freezing point. Since the piping and areas of the receiver in a molten-nitrate salt central-receiver solar power plant must be electrically heated to maintain their temperatures above the nitrate salt freezing point (430°F, 221 °C), considerable energy could be used to maintain such temperatures during nightly shutdown and bad weather. Experiments and analyses have been conducted to investigate cold filling receiver panels and piping as a way of reducing parasitic electrical power consumption and increasing the availability of the plant. The two major concerns with cold filling are (1) how far can the molten salt penetrate cold piping before freezing closed, and (2) what thermal stresses develop during the associated thermal shock. Cold fill experiments were conducted by flowing molten salt at 550°F (288°C) through cold panels, manifolds, and piping to determine the feasibility of cold filling the receiver and piping. The transient thermal responses were measured and heat transfer coefficients were calculated from the data. Nondimensional analysis is presented which quantifies the thermal stresses in a pipe or tube undergoing thermal shock. In addition, penetration distances were calculated to determine the distance salt could flow in cold pipes prior to freezing closed. © 1995 by ASME.

Understanding the evolution of porous silicon (PS) layers at the early stages of growth is important for determining the mechanism of PS film growth and controlling the film properties. We have used X-ray reflectivity (XRR) to determine the evolution of layer thickness and interfacial roughness during the growth of thin PS layers (< 200 nm) prepared by electrochemical anodization. The porous layer grows at a constant rate for films as thin as 15 nm indicating a very short incubation period during which the surface may be electropolished before the PS structure begins to form. Interface roughness measurements indicate that the top surface of the film remains relatively smooth during growth while the roughness of the PS/silicon interface increases only slightly with film thickness. The XRR results are compared with results obtained from the same films by cross-sectional transmission electron microscopy (XTEM), atomic force microscopy (AFM) and gravimetry.

Uncertainty and sensitivity analysis techniques based on Latin hypercube sampling, partial correlation analysis and stepwise regression analysis are used in an investigation with the MACCS model of the food pathways associated with a severe accident at a nuclear power station. The primary purpose of this study is to provide guidance on the variables to be considered in future review work to reduce the uncertainty in the important variables used in the calculation of reactor accident consequences. The effects of 87 imprecisely-known input variables on the following reactor accident consequences are studied: crop growing-season dose, crop long-term dose, milk growing-season dose, total food pathways dose, total ingestion pathways dose, total long-term pathways dose, area dependent cost, crop disposal cost, milk disposal cost, condemnation area, crop disposal area and milk disposal area. When the predicted variables are considered collectively, the following input variables were found to be the dominant contributors to uncertainty: fraction of cesium deposition on grain fields that is retained on plant surfaces and transferred directly to grain, maximum allowable ground concentrations of Cs-137 and Sr-90 for production of crops, ground concentrations of Cs-134, Cs-137 and I-131 at which the disposal of milk will be initiated due to accidents that occur during the growing season, ground concentrations of Cs-134, I-131 and Sr-90 at which the disposal of crops will be initiated due to accidents that occur during the growing season, rate of depletion of Cs-137 and Sr-90 from the root zone, transfer of Sr-90 from soil to legumes, transfer of Cs-137 from soil to pasture, transfer of cesium from animal feed to meat, and the transfer of cesium, iodine and strontium from animal feed to milk. © 1995.

Uncertainty and sensitivity analysis techniques based on Latin hypercube sampling, partial correlation analysis and stepwise regression analysis are used in an investigation with the MACCS model of the chronic exposure pathways associated with a severe accident at a nuclear power station. The primary purpose of this study is to provide guidance on the variables to be considered in future review work to reduce the uncertainty in the important variables used in the calculation of reactor accident consequences. The effects of 75 imprecisely known input variables on the following reactor accident consequences are studied: crop growing-season dose, crop long-term dose, water ingestion dose, milk growing-season dose, long-term groundshine dose, long-term inhalation dose, total food pathways dose, total ingestion pathways dose, total long-term pathways dose, total latent cancer fatalities, area-dependent cost, crop disposal cost, milk disposal cost, population-dependent cost, total economic cost, condemnation area, condemnation population, crop disposal area and milk disposal area. When the predicted variables are considered collectively, the following input variables were found to be the dominant contributors to uncertainty: dry deposition velocity, transfer of cesium from animal feed to milk, transfer of cesium from animal feed to meet, ground concentration of Cs-134 at which the disposal of milk products will be initiated, transfer of Sr-90 from soil to legumes, maximum allowable ground concentration of Sr-90 for production of crops, fraction of cesium entering surface water that is consumed in drinking water, groundshine shielding factor, scale factor defining resuspension, dose reduction associated with decontamination, and ground concentration of I-131 at which disposal of crops will be initiated due to accidents that occur during the growing season. Reducing the uncertainty in the preceding variables was found to substantially reduce the uncertainty in the predicted variables under consideration. For total number of latent cancer fatalities, the dominant variable was dry deposition velocity, with small effects indicated for a large number of additional variables. © 1995.

The effect of the pump, signal, and idler wave phases on three-wave nonlinear parametric mixing is investigated in a series of single-pass- gain experiments. Measurements are made with two angle-tuned KTP crystals in a 532 nm pumped, walkoff-compensated, optical parametric amplifier that is seeded by an 800 nm cw diode laser. In one of the measurements the second crystal is orientated to have its effective nonlinearity deff. of opposite sign to that of the first crystal, so that all mixing that occurred in the first crystal is canceled by the second when the phase mismatch Δkcrystal 1 = Δkcrystal 2 = 0. Efficient two-crystal amplification is subsequently restored by selecting the correct phase relationship for the three waves entering the crystal by inserting a dispersive plate between the crystals. The experimental results are explained in a straightforward manner with diagrams involving the three input wave polarizations. These results demonstrate that walkoff-compensated geometries require phase correction to achieve efficient mixing in the second crystal whenever the nonlinear interaction involves two extraordinary waves (e-waves). One practical application of this work may be lower oscillation thresholds and enhanced performance in walkoff-compensated optical parametric oscillators which use two e-waves.

The Critical Dynamics in Microgravity Experiment, DYNAMX, is under development for space flight at Sandia National Laboratories and the University of New Mexico with Dr. Rob Duncan as the Principal Investigator. This experiment will investigate the effects on the superfluid transition in 4He of currents generated by heat flow, measuring the thermal conductivity in the fluid as a function of applfed heat. DYNAMX will also take advantage of the weightless environment to measure the conductivity properties in the region of the interface between the two phases. Thus, DYNAMX represents an experiment that will explore a system driven far from equilibrium. The experiment development is sponsored by the Microgravity Science and Applications Division of NASA, with the Jet Propulsion Laboratory as the managing center. This paper will describe the science objectives, the current design of the experiment apparatus, the steps being taken to prepare this experiment for flight, and the results of ground-based feasibility demonstrations now underway.

We present magnetoluminescence data which provides a quantitative measure of the energy- band dispersion curves of novel compound semiconductor optoelectronic materials. Data for a n-type strained-layer InGaAs/GaAs (quantum-well width approximately 8 nm) and a n-type 4.5 nm-wide GaAs/AlGaAs lattice-matched single-quantum well are presented. We find that the conduction-bands are almost parabolic, with a mass of about 0.068m0 for the GaAs/AlGaAs structure. The valence-bands are nonparabolic with wave vector dependent in- plane valence-band masses varying from about 0.1m0 at zone center to about 0.3m0 for 20 meV energies.

Sol-gel processing methods are frequently used for the fabrication of lead zirconate titanate (PZT) thin films for many electronic applications. Our standard approach for film fabrication utilizes lead acetate and acetic acid modified metal alkoxides of zirconium and titanium in the preparation of our precursor solutions. This report highlights some of our recent results on the effects of the addition of a second chelating ligand, acetylacetone, to this process. We discuss the changes in film drying behavior, densification and ceramic microstructure which accompany acetylacetone additions to the precursor solution and relate the observed variations in processing behavior to differences in chemical precursor structure induced by the acetylacetone ligand. Improvements in thin film microstructure, ferroelectric and optical properties are observed when acetylacetone is added to the precursor solution.

Since both FeS2 and MoS2 are optically opaque and have bandgaps in the near IR, photochemical applications of these materials are non-existent. It is however demonstrated in the study that nanosize FeS2 and MoS2 have bandgaps that can be adjusted to the visible and even UV region of the spectrum by control of the cluster size. Discussed are measurements of size, structure, optical absorbance and photoemission for these new materials. Also, briefly outlines are synthetic procedures and novel methods for chemical processing of these nanoclusters.

We report a real-time, two-dimensional light scattering study of the evolution of structure of a two component nonionic micelle system undergoing phase separation. The micelles act like molecular slug-a-beds whose domain growth is pathetically lathargic (i.e. slower than the cube root of time prediction for simple binary fluids). In fact, the growth kinetics can be empirically described as a stretched exponential approach to a pinned domain size. Although the kinetics are not yet understood, this anomalous behavior may be due to the ability of the spherical micelles to reorganize into more complex structures.

A jib crane consists of a pendulum-like end line attached to a rotatable jib. Within this general category of cranes there exist devices with multiple degrees of freedom including variable load-line length and variable jib length. These cranes are commonly used for construction and transportation applications. Point-to-point payload maneuvers using jib cranes are performed so as not to excite the spherical pendulum modes of their cable and payload assemblies. Typically, these pendulum modes, although time-varying, exhibit low frequencies. The resulting maneuvers are therefore performed slowly, contributing to high construction and transportation costs. The crane considered here consists of a spherical pendulum attached to a rigid jib. The other end of the jib is attached to a direct drive motor of generating rotational motion. A general approach is presented for determining the open-loop trajectories for the jib rotation for accomplishing fixed-time, point-to-point, residual oscillation free, symmetric maneuvers. These residual oscillation free trajectories purposely excite the pendulum modes in such a way that at the end of the maneuver the oscillatory degrees of freedom are quiescent. Simulation results are presented with experimental verification.

First-principles density-functional calculations utilizing ab initio pseudopotentials and plane- wave expansions are used to determine lattice parameters, bulk moduli, and band structures for AlN, GaN, and InN. It is found that large numbers of plane waves are necessary to resolve the nitrogen 2p wave functions and that explicit treatment of the gallium 3d and indium 4d electrons is important for an accurate description of GaN and InN. Several properties of ternary zinc-blende alloys are determined including their bond-length and bond-angle relaxation and their energy-gap bowing parameters. The similarity of the calculated zinc- blende and wurtzite direct gaps also allows estimates to be made of the energy gap versus composition for wurtzite alloys.

To address the need for a fast path planner, we present a learning algorithm that improves path planning by using past experience to enhance future performance. The algorithm relies on an existing path planner to provide solutions to difficult tasks. From these solutions, an evolving sparse network of useful robot configurations is learned to support faster planning. More generally, the algorithm provides a framework in which a slow but effective planner may be improved both cost-wise and capability-wise by a faster but less effective planner coupled with experience. We analyze the algorithm by formalizing the concept of improvability and deriving conditions under which a planner can be improved within the framework. The analysis is based on two stochastic models, one pessimistic (on task complexity), the other randomized (on experience utility). Using these models, we derive quantitative bounds to predict the learning behavior. We use these estimation tools to characterize the situations in which the algorithm is useful and to provide bounds on the training time. In particular, we show how to predict the maximum achievable speedup. Additionally, our analysis techniques are elementary and should be useful for studying other types of probabilistic learning as well.

A simultaneous determination of both the conduction and valence-band dispersion curves (and masses) from a single compound semiconductor quantum-well structure using magnetoluminescence is discussed. Data from InGaAs/GaAs strained-single-quantum wells and GaAs/AlGaAs lattice matched quantum wells are presented. The conduction bands are found to be parabolic for densities approaching 1 × 1012cm-2. However, the valence bands are highly nonparabolic and strongly affected by heavy-hole light-hole mixing. © 1995.

Barrier layers to limit percolation through cover systems are principal features of engineered, multi-component cover designs. Conventional barrier layer components developed for humid climates have limitations in dry climates. One alternative barrier layer is a capillary barrier, which consists of a fine-over-coarse soil arrangement. The capacity of capillary barriers to laterally divert downward moving water is the key to their success. Another alternative is a dry barrier, in which atmospheric air is circulated through a coarse layer within the cover to remove water vapor. Incorporating a coarse layer which stores water for subsequent removal by air flow reduces the requirements for the air flow velocity and increases the applicability of the dry barrier.

In the US, concrete containment buildings for commercial nuclear power plants have steel liners that act as the internal pressure boundary. The liner abuts the concrete, acting as the interior concrete form. The liner is attached to the concrete by either studs or by a continuous structural shape (such as a T-section or channel) that is either continuously or intermittently welded to the liner. Studs are commonly used in reinforced concrete containments, while prestressed containments utilize a structural element as the anchorage. The practice in some countries follows the US practice, while in other countries the containment does not have a steel liner. In this latter case, there is a true double containment, and the annular region between the two containments is vented. This paper will review the practice of design of the liner system prior to the consideration of severe accident loads (overpressurization loads beyond the design conditions). An overpressurization test of a 1:6 scale reinforced concrete containment at Sandia National Laboratories resulted in a failure mechanism in the liner that was not fully anticipated. Post-test analyses and experiments have been conducted to understand the failure better. This work and the activities that followed the test are reviewed. Areas in which additional research should be conducted are given. © 1995.

We have performed computational simulations to determine how energy from a large hypervelocity impact on the Earth's surface would couple to its interior. Because of the first-order axial symmetry of both the impact energy source and the stress-wave velocity structure of the Earth, a disproportionate amount of energy is dissipated along the axis defined by the impact point and its antipode (point opposite the impact). For a symmetric and homogeneous Earth model, all the impact energy that is radiated as seismic waves into the Earth at a given takeoff angle (ray parameter), independent of azimuthal direction, is refocused (minus attenuation) on the axis of symmetry, regardless of the number of reflections and refractions it has experienced. Material on or near the axis of symmetry experiences more strain cycles with much greater amplitude than elsewhere, and therefore experiences more irreversible heating. The focusing is most intense in the upper mantle, within the asthenosphere, where seismic energy is most effectively converted to heat. For a sufficiently energetic impact, this mechanism might generate enough local heating to create an isostatic instability leading to uplift, possibly resulting in rifting, volcanism, or other rearrangement of the interior dynamics of the planet. These simulations demonstrate how hypervelocity impact energy can be transported to the Earth's interior, supporting the possibility of a causal link between large impacts on Earth and major internally-driven geophysical processes. © 1995.

A major objective of the Nuclear Regulatory Commission`s (NRC) Individual Plant Examination (IPE) Insights Program is to identify the important determinants of core damage frequency (CDF) for the different reactor and containment types and plant designs as indicated in the IPEs. The human reliability analysis (HRA) is a critical component of the probabilistic risk assessments (PRAS) which were done for the IPES. The determination and selection of human actions for incorporation into the event and fault tree models and the quantification of their failure probabilities can have an important impact on the resulting estimates of CDF and risk. Therefore, two important goals of the NRCs IPE Insights Program are (1) to determine the extent to which human actions and their corresponding failure probabilities influenced the results of the IPEs and (2) to identify which factors played significant roles in determining the differences and similarities in the results of the HRA analyses across the different plants. To obtain the relevant information, the NRC`s IPE database, which contains information on plant design, CDF, and containment performance obtained from the IPES, was used in conjunction with a systematic examination of the HRA analyses and results from the IPES. Regarding the extent to which the results of the HRA analyses were significant contributors to the plants` CDFs, examinations of several different measures indicated that while individual human actions could have important influences on CDF for particular initiators, the HRA results did not appear to be the most significant driver of plant risk (CDF). Another finding was that while there were relatively wide variations in the calculated human error probabilities (HEPs) for similar events across plants, there was no evidence for any systematic variation as a function of the HRA methods used in the analyses.

SEMATECH and the Department of Energy have established a Contamination Free Manufacturing Research Center (CFMRC) located at Sandia National Laboratories. One of the programs underway at the CFMRC is directed towards defect reduction in semiconductor process reactors by the application of computational modeling. The goal is to use fluid, thermal, plasma, and particle transport models to identify process conditions and tool designs that reduce the deposition rate of particles on wafers. The program is directed toward defect reduction in specific manufacturing tools, although some model development is undertaken when needed. The need to produce quantifiable improvements in tool defect performance requires the close cooperation among Sandia, universities, SEMATECH, SEMATECH member companies, and equipment manufacturers. Currently, both plasma (e.g., etch, PECVD) and nonplasma tools (e.g., LPCVD, rinse tanks) are being worked on under this program. In this paper the authors summarize their recent efforts to reduce particle deposition on wafers during plasma-based semiconductor manufacturing.

This is the final report on a series of experiments concerned with transient radiation-induced absorption in materials for a Cr,Nd:GSGG laser. Both the Sandia National Laboratories SPR III pulsed reactor and the Hermes III pulsed X-ray machine are used as radiation sources. The time dependence and the magnitude of the induced absorption in filter glasses and in doped and undoped LiNbO{sub 3} Q-switch materials have been measured. Gain has been observed in Cr,Nd:GSGG, the laser medium, when it is irradiated by X-rays.

We have used {sup 13}C magic-angle spinning (MAS) nuclear magnetic resonance (NMR) to characterize the structure and rotational dynamics of C{sub 60} containing oxygen molecules located in the interstitial sites of the fcc lattice. Under normal conditions, a narrow peak at 143.7 ppm is observed for C{sub 60}. When exposed to oxygen at moderate pressures, several additional resonances appear in the {sup 13}C MAS NMR spectrum. These secondary resonances are shifted downfield from the main peak at 143.7 ppm and are due to the Fermi-contact interaction of the paramagnetic oxygen molecules with the {sup 13}C nuclear spins. The presence of oxygen depresses the orientational ordering transition by ca. 20 K as observed by DSC. The spin-lattice relaxation time (T{sub 1}) of each secondary peak shows a minimum near the ordering transition, indicating that this transition is not dependent on the number of oxygen molecules surrounding an individual C{sub 60} molecule. The T{sub 1}, due to paramagnetic relaxation, normalized by the number of surrounding oxygen molecules, is constant. This observation demonstrates that within a given sample, the dynamics of C{sub 60} molecules are independent of the number of surrounding oxygen molecules.

This paper describes a process of combining two state-of-the-art CFD tools, SPRINT and INCA, in a manner which extends the utility of both codes beyond what is possible from either code alone. The speed and efficiency of the PNS code, SPRING, has been combined with the capability of a Navier-Stokes code to model fully elliptic, viscous separated regions on high performance, high speed flight systems. The coupled SPRINT/INCA capability is applicable for design and evaluation of high speed flight vehicles in the supersonic to hypersonic speed regimes. This paper describes the codes involved, the interface process and a few selected test cases which illustrate the SPRINT/INCA coupling process. Results have shown that the combination of SPRINT and INCA produces correct results and can lead to improved computational analyses for complex, three-dimensional problems.

Sampling during environmental drilling is essential to fully characterize the spatial distribution and migration of near surface contaminants. However, the analysis of these samples is not only expensive, but can take weeks or months when sent to an off-site laboratory. In contrast, measurement-while-drilling (MWD) screening capability could save money and valuable time by quickly distinguishing between contaminated and uncontaminated areas. Real-time measurements provided by a MVM system would enable on-the-spot decisions to be made regarding sampling strategies, enhance worker safety, and provide the added flexibility of being able to ``steer`` the drill bit in or out hazardous zones. During measurement-while-drilling, down-hole sensors are located behind the drill bit and linked by a rapid data transmission system to a computer at the surface. As drilling proceeds, data are collected on the nature and extent of the subsurface contamination in real-time. The down-hole sensor is a Geiger-Mueller tube (GMT) gamma radiation detector. In addition to the GMT signal, the MWD system monitors these required down-hole voltages and two temperatures associated with the detector assembly. The Gamma Ray Detection System (GRDS) and electronics package are discussed in as well as the results of the field test. Finally, our conclusions and discussion of future work are presented.

Uncertainty and sensitivity analysis techniques based on Latin hypercube sampling, partial correlation analysis and stepwise regression analysis are used in an investigation with the MACCS model of the early health effects associated with a severe accident at a nuclear power station. The primary purpose of this study is to provide guidance on the variables to be considered in future review work to reduce the uncertainty in the important variables used in the calculation of reactor accident consequences. The effects of 34 imprecisely known input variables on the following reactor accident consequences are studied: number of early fatalities, number of cases of prodromal vomiting, population dose within 10 mi of the reactor, population dose within 1000 mi of the reactor, individual early fatality probability within 1 mi of the reactor, and maximum early fatality distance. When the predicted variables are considered collectively, the following input variables were found to be the dominant contributors to uncertainty: scaling factor for horizontal dispersion, dry deposition velocity, inhalation protection factor for nonevacuees, groundshine shielding factor for nonevacuees, early fatality hazard function alpha value for bone marrow exposure, and scaling factor for vertical dispersion.

This report summarizes two approaches to time-optimal control of a nonlinear magnetically levitated platen. The system of interest is a candidate technology for next-generation photolithography machines used in the manufacture of integrated circuits. The dynamics and the variable peak control force of the electro-magnetic actuators preclude the direct application of classical time-optimal control methodologies for determining optimal rest-to-rest maneuver strategies. Therefore, this study explores alternate approaches using a previously developed computer simulation. In the first approach, conservative estimates of the available control forces are used to generate suboptimal switching curves. In the second approach, exact solutions are determined iteratively and used as a training set for an artificial neural network. The trained network provides optimal actuator switching times that incorporate the full nonlinearities of the magnetic levitation actuators. Sample problems illustrate the effectiveness of these techniques as compared to traditional proportional-derivative control.

Active control of structures has been under intensive development for the last ten years. Reference 2 reviews much of the identification and control technology for structural control developed during this time. The technology was initially focused on space structure and weapon applications; however, recently the technology is also being directed toward applications in manufacturing and transportation. Much of this technology focused on multiple-input/multiple-output (MIMO) identification and control methodology because many of the applications require a coordinated control involving multiple disturbances and control objectives where multiple actuators and sensors are necessary for high performance. There have been many optimal robust control methods developed for the design of MIMO robust control laws; however, there appears to be a significant gap between the theoretical development and experimental evaluation of control and identification methods to address structural control applications. Many methods have been developed for MIMO identification and control of structures, such as the Eigensystem Realization Algorithm (ERA), Q-Markov Covariance Equivalent Realization (Q-Markov COVER) for identification; and, Linear Quadratic Gaussian (LQG), Frequency Weighted LQG and H-/ii-synthesis methods for control. Upon implementation, many of the identification and control methods have shown limitations such as the excitation of unmodelled dynamics and sensitivity to system parameter variations. As a result, research on methods which address these problems have been conducted.

This paper describes numerical simulations that were performed to study laminar flow through a square duct with a 900 bend. The purpose of this work was two fold. First, an improved understanding was desired of the flow physics involved in the generation of secondary vortical flows in three-dimensions. Second, adaptive gridding techniques for structured grids in three- dimensions were investigated for the purpose of determining their utility in low Reynolds number, incompressible flows. It was also of interest to validate the commercial computer code CFD-ACE. Velocity predictions for both non-adaptive and adaptive grids are compared with experimental data. Flow visualization was used to examine the characteristics of the flow though the curved duct in order to better understand the viscous flow physics of this problem. Generally, moderate agreement with the experimental data was found but shortcomings in the experiment were demonstrated. The adaptive grids did not produce the same level of accuracy as the non-adaptive grid with a factor of four more grid points.

A series of experiments was conducted to determine hydrogen combustion behavior under conditions of rapidly condensing steam caused by water sprays. Experiments were conducted in the Surtsey facility under conditions that were nearly prototypical of those that would be expected in a severe accident in the CE System 80+ containment. Mixtures were initially nonflammable owing to dilution by steam. The mixtures were ignited by thermal glow plugs when they became flammable after sufficient steam was removed by condensation caused by water sprays. No detonations or accelerated flame propagation was observed in the Surtsey facility. The combustion mode observed for prototypical mixtures was characterized by multiple deflagrations with relatively small pressure rises. The thermal glow plugs were effective in burning hydrogen safely by igniting the gases as the mixtures became marginally flammable.

This report identifies the key features noted as requirements in the diagnostic decision-making process of Single Photon Emission Computed Tomography (SPECT) cardiac imaging. The report discusses the critical issues that create the basic system framework for design of an automatic target recognizer (ATR) algorithm prototype to support diagnosis of coronary artery disease. Candidate feature discovery algorithms that may form the basis of future work include Adaptive Resonance Theory and Bayesian Decision Network. A framework for the practitioner-Human-System-Interface would include baseline patient history and demographic data; reference cardiac imagery history; and current overlay imagery to provide complementary information (i.e., coronary angiography, echocardiography, and SPECT images). The goal is to design a prototype that would represent a fused present and historical {open_quotes}whole{close_quotes} functional, structural, and physiologic cardiac patient model. This framework decision-assisting platform would be available to practitioner and student alike, with no {open_quotes}real-world{close_quotes} consequences.

This report describes the process used by Sandia National Laboratories, New Mexico to characterize weapon hardware for disposition. The report describes the following basic steps: (1) the drawing search process and primary hazard identification; (2) the development of Disassembly Procedures (DPs), including demilitarization and sanitization requirements; (3) the generation of a ``disposal tree``; (4) generating RCRA waste disposal information; and (5) documenting the information. Additional data gathered during the characterization process supporting hardware grouping and recycle efforts is also discussed.

Supercomputing `94, a high-performance computing and communications conference, was held November 14th through 18th, 1994 in Washington DC. For the past four years, Sandia National Laboratories has used this conference to showcase and focus its communications and networking endeavors. At the 1994 conference, Sandia built a Switched Multimegabit Data Service (SMDS) network running at 44.736 megabits per second linking its private SMDS network between its facilities in Albuquerque, New Mexico and Livermore, California to the convention center in Washington, D.C. For the show, the network was also extended from Sandia, New Mexico to Los Alamos National Laboratory and from Sandia, California to Lawrence Livermore National Laboratory. This paper documents and describes this network and how it was used at the conference.

The interstitial oxygen (O{sub i}) concentration in Czochralski silicon and the subsequent SiO{sub x} precipitation are important parameters for integrated circuit fabrication. Uncontrolled SiO{sub x} precipitation during processing can create detrimental mechanical and electrical effects that contribute to poor performance. An inability to consistently and accurately measure the initial O{sub i} concentration in heavily doped silicon has led to contradictory results regarding the effects of dopant type and concentration on SiO{sub x} precipitation. The authors have developed a software package for reliably determining and comparing O{sub i} in heavily doped silicon. The SiFTIR{copyright} code implements three independent oxygen analysis methods in a single integrated package. Routine oxygen measurements are desirable over a wide range of silicon resistivities, but there has been confusion concerning which of the three numerical methods is most suitable for the low resistivity portion of the continuum. A major strength of the software is an ability to rapidly produce results for all three methods using only a single Fourier Transform Infrared Spectroscopy (FTIR) spectrum as input. This ability to perform three analyses on a single data set allows a detailed comparison of the three methods across the entire range of resistivities in question. Integrated circuit manufacturers could use the enabling technology provided by SiFTIR{copyright} to monitor O{sub i} content. Early detection of O{sub i} using this diagnostic could be beneficial in controlling SiO{sub x} precipitation during integrated circuit processing.

FITTING is a Fortran subroutine that constructs a smooth, generalized four-parameter probability distribution model. It is fit to the first four statistical moments of the random variable X (i.e., average values of X, X{sup 2}, X{sup 3}, and X{sup 4}) which can be calculated from data using the associated subroutine CALMOM. The generalized model is produced from a cubic distortion of the parent model, calibrated to match the first four moments of the data. This four-moment matching is intended to provide models that are more faithful to the data in the upper tail of the distribution. Examples are shown for two specific cases.

This report documents a study (Stage Right Operational Safety Analysis) that was performed to evaluate the effects of new Stage Right operations on the safety of Pantex personnel who perform the operations and maintain the equipment. The primary concern of the evaluation was for personnel safety during Stage Right operations, but operations equipment damage and degradation also were taken into account. This analysis evaluates safety of the work process in the staging of dismantled nuclear weapon pits within the modified Richmond magazines only. This Stage Right Process and Operational Safety Analysis includes the following processes: moving the pelletized drums from the pallet trailer to the pallet turner, staging of pallets and removal of pallets from the magazine, recovery from an incident in a magazine, setting up, opening, and closing a Zone 4 magazine, inventory of pelletized drums in the magazines, transporting pelletized drums from Zone 12 to Zone 4, and maintenance on the shielded lift truck that involves removal of the cab shielding. The analysis includes the following undesirable consequences: injury to personnel, breach of an AL-R8 container, drop of a loaded pallet, damage to equipment, and equipment unreliability.

The development of two new probabilistic accident consequence codes, MACCS and COSYMA, was completed in 1990. These codes estimate the risks presented by nuclear installations based on postulated frequencies and magnitudes of potential accidents. In 1991, the US Nuclear Regulatory Commission (NRC) and the Commission of the European Communities (CEC) began a joint uncertainty analysis of the two codes. The ultimate objective of the joint effort was to develop credible and traceable uncertainty distributions for the input variables of the codes. Expert elicitation was identified as the best technology available for developing a library of uncertainty distributions for the selected consequence parameters. The study was formulated jointly and was limited to the current code models and to physical quantities that could be measured in experiments. Experts developed their distributions independently. To validate the distributions generated for the wet deposition input variables, samples were taken from these distributions and propagated through the wet deposition code model. Resulting distributions closely replicated the aggregated elicited wet deposition distributions. To validate the distributions generated for the dispersion code input variables, samples from the distributions and propagated through the Gaussian plume model (GPM) implemented in the MACCS and COSYMA codes. Project teams from the NRC and CEC cooperated successfully to develop and implement a unified process for the elaboration of uncertainty distributions on consequence code input parameters. Formal expert judgment elicitation proved valuable for synthesizing the best available information. Distributions on measurable atmospheric dispersion and deposition parameters were successfully elicited from experts involved in the many phenomenological areas of consequence analysis. This volume is the first of a three-volume document describing the project.

An ovenized 10 pF standard capacitor was constructed by the National Institute of Standards and Technology (NIST). The dielectric material used as Wuprasil II grade fused silica. This report discusses a temperature coefficient analysis of the capacitor performed at the Primary Standards Laboratory (PSL) of Sandia National Laboratories (SNL). The effects of temperature change on dielectric loss will also be discussed.

A common limitation to performance in data acquisition systems is storage of the collected data. Compressing the data would increase the amount of data that could be stored. However, most compression routines require that the data be collected and analyzed before compression is performed. Also, these compression routines often store the information required for decompression along with the data, thus decreasing the storage available for data. One solution to this problem is to create an encoding tree known to both the encoder and the decoder based on apriori knowledge of the data. Once the tree is created, optimal encoding schemes such as the Huffman algorithm may be used on the data as it is being collected. In this way the data is compressed as each byte is received and there is no overhead associated with storing decompression data. In this paper the idea of using a fixed Huffman tree is explored and the results are compared to a defacto standard in data compression, PKZIP.

Experiments have been conducted with a molten salt loop at Sandia National Laboratories in Albuquerque, NM to resolve issues associated with the operation of the 10MW{sub e} Solar Two Central Receiver Power Plant located near Barstow, CA. The salt loop contained two receiver panels, components such as flanges and a check valve, vortex shedding and ultrasonic flow meters, and an impedance pressure transducer. Tests were conducted on procedures for filling and thawing a panel, and assessing components and instrumentation in a molten salt environment. Four categories of experiments were conducted: (1) cold filling procedures, (2) freeze/thaw procedures, (3) component tests, and (4) instrumentation tests. Cold-panel and -piping fill experiments are described, in which the panels and piping were preheated to temperatures below the salt freezing point prior to initiating flow, to determine the feasibility of cold filling the receiver and piping. The transient thermal response was measured, and heat transfer coefficients and transient stresses were calculated from the data. Freeze/thaw experiments were conducted with the panels, in which the salt was intentionally allowed to freeze in the receiver tubes, then thawed with heliostat beams. Slow thermal cycling tests were conducted to measure both how well various designs of flanges (e.g., tapered flanges or clamp type flanges) hold a seal under thermal conditions typical of nightly shut down, and the practicality of using these flanges on high maintenance components. In addition, the flanges were thermally shocked to simulate cold starting the system. Instrumentation such as vortex shedding and ultrasonic flow meters were tested alongside each other, and compared with flow measurements from calibration tanks in the flow loop.

A dry barrier may be formed by circulating dry air through a soil layer above or below a waste disposal site, thus reducing the soil moisture content to very low values. Drying a horizontal soil layer creates a barrier to vertical water movement in three ways. First, the drying removes water from the system, intercepting water infiltrating down from the surface. Second, drying a soil layer increases its water storage capacity so the soil will tend to retain rather than transmit water. Third, as a soil layer dries, moisture is removed from progressively smaller interstitial pores so that the hydraulic conductivity of the formation (for liquid flow) decreases. For example, the hydraulic conductivity of a typical sand may decrease by three orders of magnitude as its moisture content is reduced from 20 to 10 percent. This study analyzed the technical and economic feasibility of the subsurface dry barrier concept for containment of a migrating contaminant plume in unsaturated soil. The concept was shown to be a viable option for limiting aqueous migration of pollutants through unsaturated media, with estimated capital costs of between $130,000 and $260,000 for a 1-hectare barrier, and annual operating costs of $10,000 per year.

As photovoltaic (PV) systems gain more acceptance in utility-interactive applications throughout the world, many organizations are placing increasingly higher priorities on writing guidelines, codes and standards. These guidelines and codes are being written to improve safety, installation, acceptance, listing or certification of the PV components or systems. Sandia National Laboratories` PV System Applications Department is working closely with the PV industry to address issues that are associated with fire and personnel safety and with National Electrical Code (NEC) requirements. Additionally, the United States has agreed to participate in two of the International Energy Agency (IEA) Annexes (topical tasks) of the Implementing Agreement for a Cooperative Programme on Photovoltaic Power Systems. This paper describes events and activities associated with the NEC and the IEA that are being led by Sandia National Laboratories with broad participation by the US PV industry.

A method is reported for generating mechanical spacecraft propulsion from unsymmetrical magnetic induction fields. It is based on an unsymmetrical three-dimensional loop antenna structure driven by a repetitively-pulsed high-current power supply. Antenna geometry is optimized for generating propulsive thrust rather than radiating electromagnetic energy. Part of this antenna consists of flat electrical conductors, which form a partially-closed quasi-cylindrical volume around a center conductor. Magnetic flux concentrates at the closed end of the quasicylindrical volume thereby creating a magnetic field flux density gradient along a single axis collinear to the Center Conductor. This magnetic field density gradient imbalances the magneto-mechanical forces that result from the interactions of the internal magnetic induction field with the current in the conductors of the antenna structure, in accordance with Lorentz`s Force Law. Also, there are electrically isolated prismatic conductor surfaces attached to the inside surface of the flat conductors which form the closed end of the quasi-cylindrical volume. Mechanical pressures occur on these conductor prisms because of the changing internal magnetic field and are a consequence of Faraday`s Induction Law and Lenz`s Law. Input current rise time and wave shape are crucial to maximizing spacecraft propulsive thrust.

The Department of Energy is conducting an ongoing investigation of the consequences of taking fuel burnup into account in the design of spent fuel transportation packages. A series of experiments, collectively called the Spent Fuel Safety Experiment (SFSX), has been devised to provide integral benchmarks for testing computer-generated predictions of spent fuel behavior. A set of experiments is planned in which sections of unirradiated fuel rods are interchanged with similar sections of spent PWR fuel rods in a critical assembly. By determining the critical size of the arrays, one can obtain benchmark data for comparison with criticality safety calculations. The integral reactivity worth of the spent fuel can be assessed by comparing the measured delayed critical fuel loading with and without spent fuel. An analytical effort to model the experiments and anticipate the core loadings required to yield the delayed critical conditions runs in parallel with the experimental effort.

The chemical inertness and high bond strengths of the 3-5 nitrides lead to slower plasma etching rates than for more conventional 3-5 semiconductors under the same conditions. High ion density conditions (greater than 3 x 10(exp 11) cm(exp {minus}3)) such as those obtained in ECR or magnetron reactors produce etch rates up to an order of magnitude higher than for RIE, where the ion densities are in the 10(exp 9) cm(exp {minus}3) range. The authors have developed smooth anisotropic dry etches for GaN, InN, AlN and their alloys based on Cl2/CH4/H2/Ar, BCl3/Ar, Cl2/H2, Cl2/SF6, HBr/H2 and HI/H2 plasma chemistries achieving etch rates up to approx. 4,000 A/min at moderate dc bias voltages (less than or equal to {minus}150 V). Ion-induced damage in the nitrides appears to be less apparent than in other 3-5`s. One of the key remaining issues is the achievement of high selectivities for removal of one layer from another.

Quantum well microdisk laser structures have been fabricated in the GaN/InGaN, GaAs/AlGaAs and GaAs/InGaP systems using a combination of ECR dry etching Cl2/CH4/H2/Ar, BCl3/Ar or CH4/H2/Ar plasma chemistries respectively, and subsequent wet chemical etching of a buffer layer underlying the quantum wells. While wet etchants such as HF/H2O and HCl/HNO3/H2O are employed for AlGaAs and InGaP, respectively, a new KOH based solution has been developed for AlN which is completely selective over both GaN and InGaN. Typical mask materials include PR or SiN(x), while the high surface recombination velocity of exposed AlGaAs (approximately) 10(exp 5)cm(center dot)/sec requires encapsulation with ECR-CVD SiN(x) to stabilize the optical properties of the modulators.

This [updated 1/95] report outlines the technology of modern solar central receiver power plants, showing how they could be an important domestic source of energy within the next decade

The microstructure of Al/{alpha}-Al{sub 2}0{sub 3} composites made by infiltrating Al into dense mullite preforms has been characterized using transmission electron microscopy. Observations revealed that the formation of the Al/Al{sub 2}0{sub 3} composites involves three stages. Initially, Al infiltrates into a dense mullite preform through grain boundary diffusion, and reacts with mullite at grain boundaries to form a partial reaction zone. Then, a complete reaction takes place in the reaction region between the partial reaction zone and the full reaction zone to convert the dense mullite preform to a composite of {alpha}-Al{sub 2}0{sub 3} (matrix) and an Al-Si phase (thin channels). Finally, the reduced Si from the reaction diffuses out of the Al/Al{sub 2}0{sub 3} composite through the metal channels, whereas Al from the molten Al pool is continuously drawn to the reaction region until the mullite preform is consumed or the sample is removed from the molten Al pool. Based on the observed microstructure, infiltration mechanisms have been discussed, and a growth model of the composites is proposed in which the process involves repeated nucleation of Al{sub 2}0{sub 3} grains and grain growth.

Copper chemical vapor deposition using liquid coinjection of the Cu(I) precursor (hfac)Cu(TMVS) along with TMVS has been demonstrated. The coinjection of TMVS with (hfac)Cu(TMVS) stabilizes the Cu precursor until it enters the reaction chamber, allowing for better control of the deposition and faster deposition rates. Using this technique, we have grown films with as-deposited resistivities of 1.86 {plus_minus} 0.04 {mu}{Omega}-cm, independent of film thickness. Deposition rates of well over 100 nm/min are possible. Good step coverage and gap fill down to 0.6 {mu}m lines is demonstrated, with gap fill being limited by the large Cu grain sizes in these films.

Very highly porous (aerogel) silica films with refractive index in the range 1.006--1.05 (equivalent porosity 98.5--88%) were prepared by an ambient-pressure process. It was shown earlier using in situ ellipsometric imaging that the high porosity of these films was mainly attributable to the dilation or `springback` of the film during the final stage of drying. This finding was irrefutably reconfirmed by visually observing a `springback` of >500% using environmental scanning electron microscopy (ESEM). Ellipsometry and ESEM also established the near cent per cent reversibility of aerogel film deformation during solvent intake and drying. Film thickness profile measurements (near the drying line) for the aerogel, xerogel and pure solvent cases are presented from imaging ellipsometry. The thickness of these films (crack-free) were controlled in the range 0.1-3.5 {mu}m independent of refractive index.

The pore size r{sub p} in a gel is determined by the extent of shrinkage of the gel network during drying. Shrinkage is driven by the collapse of the gel network in response to the capillary pressure P{sub c} exerted by the pore fluid. The extent of shrinkage depends on the balance between the capillary pressure P{sub c} in the pore fluid and the bulk modulus K{sub p} of the gel. The hydraulic pore radius, r{sub H} = 2V{sub p}/S{sub a}, where V{sub p} is the pore volume and S{sub a} is the apparent N{sub 2} BET surface area, is often used to characterize the pore size of a gel. A series of acid catalyzed silica gels dried in pore fluids with different {gamma}{sub lv}, showed that there is a limit to the minimum apparent r{sub H} obtainable in a gel, and when the volume fraction of porosity {phi} {le} 0.37, r{sub H} becomes constant and {approximately}0.8 nm. In contrast, experimental data show that the true pore size r{sub p} of gels continues to decrease when {phi} {le} 0.37. Analysis of their adsorption isotherms show that while r{sub H} apparently stays constant: (a) the BET C constant continues to increase, (b) the width and average of their pore size distributions continue to decrease, and (c) as shrinkage continues the gels eventually become non-porous to N{sub 2} at 77K but are still porous to CO{sub 2} at 273K. This paper reviews these results and addresses micropore formation in silica gels with the goal of determining how P{sub c} influences the final r{sub p}, and why r{sub p} and r{sub H} diverge when {phi} {le} 0.37.

A computational/analytical technique has been developed which models the physics of high pressure gas atomization. The technique uses an uncoupled approach, such that the gas flowfield is initially calculated with a commercially-available Navier-Stokes code. The liquid metal droplet breakup, dynamics, and thermodynamics, are then calculated using the pre-computed flowfield by a separate computer program written by the authors. The atomization code models the primary breakup of the liquid metal stream, tracks the droplets resulting from primary breakup through the flowfield until they undergo secondary breakup, and then tracks the subdroplets until they breakup, solidify, or leave the flowfield region of interest. The statistical properties of the metal powder produced are then computed from the characteristics of these droplets. Comparisons between experimental measurements and computations indicate that the Navier-Stokes code is predicting the gas flowfield well, and that the atomization code is properly modeling the physics of the droplet dynamics and breakup.

Modern wind turbines are fatigue critical machines used to produce electrical power. To insure long term, reliable operation, their structure must be optimized if they are to be economically viable. The fatigue and reliability projects in Sandia`s Wind Energy Program are developing the analysis tools required to accomplish these design requirements. The first section of the paper formulates the fatigue analysis of a wind turbine using a cumulative damage technique. The second section uses reliability analysis for quantifying the uncertainties and the inherent randomness associated with turbine performance and the prediction of service lifetimes. Both research areas are highlighted with typical results.

This report contains research in the following areas related to beam transport for a common ion driver: multi-gap acceleration; neutralization with electrons; gas neutralization; self-pinched transport; HIF and LIF transport, and relevance to common ion driver; LIF and HIF reactor concepts and relevance to common ion driver; atomic physics for common ion driver; code capabilities and needed improvement.

There are major differences between the safety principles for nuclear weapons and for nuclear reactors. For example, a principal concern for nuclear weapons is to prevent electrical energy from reaching the nuclear package during accidents produced by crashes, fires, and other hazards, whereas the foremost concern for nuclear reactors is to maintain coolant around the core in the event of certain system failures. Not surprisingly, new methods have had to be developed to assess the risk from nuclear weapons. These include fault tree transformations that accommodate time dependencies, thermal and structural analysis techniques that are fast and unconditionally stable, and Monte-Carlo-based sampling methods that incorporate intelligent searching. This paper provides an overview of the new methods for nuclear weapons, compares them with existing methods for nuclear reactors, identifies some of their dual-use characteristics, and discusses ongoing developmental activities.

The authors study the following problem: given a collection A of polyhedral parts in 3D, determine whether there exists a subset S of the parts that can be moved as a rigid body by an infinitesimal translation and rotation, without colliding with the rest of the parts, A/S. A negative result implies that the object whose constituent parts are the collection A cannot be taken apart with two hands. A positive result, together with the list of movable parts in S and a direction of motion for S, can be used by an assembly sequence planner. This problem has attracted considerable attention within and outside the robotics community. They devise an efficient algorithm to solve this problem. The solution is based on the ability to focus on selected portions of the tangent space of rigid motions and efficiently access these portions. The algorithm is complete (in the sense that it is guaranteed to find a solution if one exists), simple, and improves significantly over the best previously known solutions. The authors report experimental results with an implementation of their algorithm.

The first remediation of an Environmental Restoration (ER) Project site at Sandia National Laboratories (SNL) was successfully conducted in May and June 1994 at Technical Area II. The removal action involved four Uranium Calibration Pits (UCPs) filled with radioactive or hazardous materials. The concrete culvert pits were used to test and calibrate borehole radiometric logging tools for uranium exploration. The removal action consisted of excavating and containerizing the pit contents and contaminated soil beneath the culverts, removing the four culverts, and backfilling the excavation. Each UCP removal had unique complexities. Sixty 208-L drums of solid radioactive waste and eight 208-L drums of liquid hazardous waste were generated during the VCM. Two of the concrete culverts will be disposed as radioactive waste and two as solid waste. Uranium-238 was detected in UCP-2 ore material at 746 pci/g, and at 59 pci/g in UCP-1 silica sand. UCP-4 was empty; sludge from UCP-3 contained 122 mg/L (ppm) chromium.

An experiment involving migration of fluid and tracers (Li, Br, Ni) through a 6-m-high x 3-m-dia caisson Wedron 510 sand, is being carried out for Yucca Mountain Site Characterization Project. Sand`s surface chemistry of the sand was studied and a preliminary surface-complexation model of Ni adsorption formulated for transport calculations. XPS and leaching suggest that surface of the quartz sand is partially covered by thin layers of Fe-oxyhydroxide and Ca-Mg carbonate and by flakes of kaolinite. Ni adsorption by the sand is strongly pH-dependent, showing no adsorption at pH 5 and near-total adsorption at pH 7. Location of adsorption edge is independent of ionic strength and dissolved Ni concentration; it is shifted to slightly lower pH with higher pCO2 and to slightly higher pH by competition with Li. Diminished adsorption at alkiline pH with higher pCO2 implies formation of dissolved Ni-carbonato complexes. Ni adsorption edges for goethite and quartz, two components of the sand were also measured. Ni adsorption on pure quartz is only moderately pH-dependent and differs in shape and location from that of the sand, whereas Ni adsorption by goethite is strongly pH-dependent. A triple-layer surface-complexation model developed for goethite provides a good fit to the Ni-adsorption curve of the sand. Based on this model, the apparent surface area of the Fe-oxyhydroxide coating is estimated to be 560 m{sup 2}/g, compatible with its occurrence as amorphous Fe-oxyhydroxide. Potentiometric titrations on sand also differ from pure quartz and suggest that effective surface area of sand may be much greater than that measured by N{sub 2}-BET gas adsorption. Attempts to model the adsorption of bulk sand in terms of properties of pure end member components suggest that much of the sand surface is inert. Although the exact Ni adsorption mechanisms remain ambiguous, this preliminary adsorption model provides an initial set of parameters that can be used in transport calculations.

We have used several sol-gel strategies to prepare supported inorganic membranes by a process that combines the features of slip-casting and dip-coating. To be viable the deposited membranes must exhibit both high flux and high selectivity. For porous membranes these requirements are met by extremely thin, defect-free porous films exhibiting a narrow size distribution of very small pores. This paper considers the use of polymeric silica and hybrid-organosilyl precursor sols in the context of the underlying physics and chemistry of the membrane deposition process. Since the average membrane pore size is ultimately established by the collapse of the gel network upon drying, it is necessary to promote polymer interpenetration and collapse during membrane deposition in order to achieve the very small pore sizes necessary for molecular sieving. For polymeric sols, this is accomplished using rather weakly branched polymers characterized by fractal dimension D < 1.5 under deposition conditions in which the silica condensation rate is minimized. By analogy to organic polymer sols and gels, we believe that the breadth of the pore size distribution can be influenced by the occurrence of micro-phase separation during membrane deposition. Minimization of the condensation rate not only fosters polymer collapse but should inhibit phase separation, leading to a narrower pore size distribution. The formation of microporosity through collapse of the gel network requires that small pores are achieved at the expense of membrane porosity. Incorporation of organic template ligands within a dense silica matrix followed by their removal allows us to independently control pore size and pore volume through the size and volume fraction of the organic template. Such strategies can be used to create microporous films with large volume fraction porosities.

The Solar Thermal Design Assistance Center (STDAC) at Sandia is a resource provided by the DOE Solar Thermal Program. The STDAC`s major objective is to accelerate the use of solar thermal systems by providing direct technical assistance to users in industry, government, and foreign countries; cooperating with industry to test, evaluate, and develop renewable energy systems and components; and educating public and private professionals, administrators, and decision makers. This FY94 report highlights the activities and accomplishments of the STDAC. In 1994, the STDAC continued to provide significant direct technical assistance to domestic and international organizations in industry, government, and education, Applying solar thermal technology to solve energy problems is a vital element of direct technical assistance. The STDAC provides information on the status of new, existing, and developing solar technologies; helps users screen applications; predicts the performance of components and systems; and incorporates the experience of Sandia`s solar energy personnel and facilities to provide expert guidance. The STDAC directly enhances the US solar industry`s ability to successfully bring improved systems to the marketplace. By collaborating with Sandia`s Photovoltaic Design Assistance Center and the National Renewable Energy Laboratory the STDAC is able to offer each customer complete service in applying solar thermal technology. At the National Solar Thermal Test Facility the STDAC tests and evaluates new and innovative solar thermal technologies. Evaluations are conducted in dose cooperation with manufacturers, and the results are used to improve the product and/or quantify its performance characteristics. Manufacturers, in turn, benefit from the improved design, economic performance, and operation of their solar thermal technology. The STDAC provides cost sharing and in-kind service to manufacturers in the development and improvement of solar technology.

Recent results in the use of disilanes as silylating reagents for near-surface imaging with deep-UV (248 nm) and EUV (13.5 nm) lithography are reported. A relatively thin imaging layer of a photo-cross-linking resist is spun over a thicker layer of hard-baked resist that functions as a planarizing layer and antireflective coating. Photoinduced acid generation and subsequent heating crosslinks and renders exposed areas impermeable to an aminodisilane that reacts with the unexposed regions. Subsequent silylation and reactive ion etching afford a positive-tone image. The use of disilanes introduces a higher concentration of silicon into the polymer than is possible with silicon reagents that incorporate only one silicon atom per reactive site. The higher silicon content in the silylated polymer increases etching selectivity between exposed and unexposed regions and thereby increases the contrast. Additional improvements that help to minimize flow during silylation are also discussed, including the addition of bifunctional disilanes. We have resolved high aspect ratio, very high quality 0.20 {mu}m line and space patterns at 248 nm with a stepper having a numerical aperture (NA)= 0.53, and have resolved {<=} 0.15 {mu}m line and spaces at 13.5 nm.

Sputtered MoS{sub 2} is a solid lubricant capable of ultralow friction coefficients (below 0.05) load-bearing capacity. Since it exhibits low friction in vacuum, low outgassing rate, is non-migrating and lacks organic binders, this material is an attractive lubricant for space mechanisms. To exploit these new materials to their fullest potential, designers of space-based motion systems require data on the effects of atomic oxygen exposure on dense, sputtered MoS{sub 2}. This paper describes the effects of atomic oxygen in low earth orbit on the friction and surface composition of sputtered MoS{sub 2} films. Sputtered multilayer films of MoS{sub 2} with nickel (0.7 nm Ni per 10 nm MoS{sub 2}, for 1 {mu}m total film thickness), and MoS{sub 2} cosputtered with antimony oxide (nominally 2 {mu}m thick) were exposed to 2.2 to 2.5 x 10{sup 20} oxygen/cm{sup 2} over a period of 42.25 hours in earth orbit on the United States space shuttle. Identical specimens were kept as controls in desiccated storage for the duration of the mission, and another set was exposed to an equivalent fluence of atomic oxygen in the laboratory. The friction coefficient in air and vacuum, and the composition of worn surfaces, were determined prior to the shuttle flight and again after the shuttle flight. Results are described.

High heat flux testing for the United States fusion power program is the primary mission of the Plasma Materials Test Facility (PMTF) located at Sandia National Laboratories - New Mexico. This facility, which is owned by the United States Department of Energy, has been in operation for over 17 years and has provided much of the high heat flux data used in the design and evaluation of plasma facing components for many of the world`s magnetic fusion, tokamak experiments. In addition to domestic tokamaks such as Tokamak Fusion Test Reactor (TFTR) at Princeton and the DIII-D tokamak at General Atomics, components for international experiments like TEXTOR, Tore-Supra, and JET also have been tested at the PMTF. High heat flux testing spans a wide spectrum including thermal shock tests on passively cooled materials, thermal response and thermal fatigue tests on actively cooled components, critical heat flux-burnout tests, braze reliability tests and safety related tests. The objective of this article is to provide a brief overview of the high heat flux testing capabilities at the PMTF and describe a few of the experiments performed over the last year.

Thermal response and thermal fatigue tests of four 5 mm thick beryllium tiles on a Russian divertor mock-up were completed on the Electron Beam Test System at Sandia National Laboratories. The beryllium tiles were diffusion bonded onto an OFHC copper saddleblock and a DSCu (MAGT) tube containing a porous coating. Thermal response tests were performed on the tiles to an absorbed heat flux of 5 MW/m{sup 2} and surface temperatures near 300{degrees}C using 1.4 MPa water at 5.0 m/s flow velocity and an inlet temperature of 8-15{degrees}C. One tile was exposed to incrementally increasing heat fluxes up to 9.5 MW/m{sup 2} and surface temperatures up to 690{degrees}C before debonding at 10 MW/m{sup 2}. A third tile debonded after 9200 thermal fatigue cycles at 5 MW/m{sup 2}, while another debonded after 6800 cycles. In all cases, fatigue failure occurred in the intermetallic layers between the beryllium and copper. No fatigue cracking of the bulk beryllium was observed. During thermal cycling, a gradual loss of porous coating produced increasing sample temperatures. These experiments indicate that diffusion-bonded beryllium tiles can survive several thousand thermal cycles under ITER relevant conditions without failure. However, the reliability of the diffusion bonded Joint remains a serious issue.

This paper illustrates how different modes of operation such as bilateral teleoperation, autonomous control, and shared control can be described and implemented using combinations of modules in the SMART robot control architecture. Telerobotics modes are characterized by different ``grids`` of SMART icons, where each icon represents a portion of run-time code that implements a passive control law. By placing strict requirements on the module`s input-output behavior and using scattering theory to develop a passive sampling technique, a flexible, expandable telerobot architecture is achieved. An automatic code generation tool for generating SMART systems is also described.

This report provides brief summaries of research performed in chemical and physical sciences at Sandia National Laboratories. Programs are described in the areas of advanced materials and technology, applied physics and chemistry, lasers, optics, and vision, and resources and capabilities.

Industrial and military activities in the US produce large amounts of hazardous mixed waste, which includes both radioactive and toxic substances. The already overburdened environment is faced with the task of safely disposing of these complex wastes. A very important aspect of this effort is the safe and economical transportation of radioactive and toxic chemical wastes to projected repositories. Movement of wastes to the repository sites is accomplished by a combination of truck, rail, ship, and air. The DOE directs transportation activities including cask development technology for use in single or multimode transport. Sandia National Laboratories` Transportation Technology programs provide the technology and know-how to support DOE in achieving safe, efficient, and economical packaging and transportation of nuclear and other hazardous waste materials. This brochure describes the Transportation Technology programs and the specialized techniques and capabilities they offer to prospective users.

This report consists of one engineering drawing showing the design of the Fifth Wheel System for a semi-tractor trailer truck. Notes on the drawing give instructions for installation of some items, references to other drawings and instructions, and testing procedures.

This report consists of two engineering drawings showing the electrical and pneumatic system for the Fifth Wheel System on a semi-tractor trailer truck. The system is shown in the nonactivated state.

This report consists of one engineering drawing showing modifications to the Fifth Wheel System for a semi-tractor trailer truck. Notes give instructions for installation of some items, where other items may be purchased, testing instructions, and shipping instructions.

This report consists on one engineering drawing showing the wiring scheme for the Fifth Wheel System for a semi-tracker trailer truck. A note explains what wire is specified.

The development of software for use in high-consequence systems mandates rigorous (formal) processes, methods, and techniques to improve the safety characteristics of those systems. This paper provides a brief overview of current research and practices in high-consequence software, including applied design methods. Some of the practices that are discussed include: fault tree analysis, failure mode effects analysis, petri nets, both hardware and software interlocks, n-version programming, Independent Vulnerability Analyses, and watchdogs. Techniques that offer improvement in the dependability of software in high-consequence systems applications are identified and discussed. Limitations of these techniques are also explored. Research in formal methods, the cleanroom process, and reliability models are reviewed. In addition, current work by several leading researchers as well as approaches being used by leading practitioners are examined.

The five Solar Electric Generating Systems (SEGS) at Kramer Junction, California, now have nearly 30 years of cumulative operating experience. These 30 MW plants employ parabolic trough technology originally deployed by LUZ International in the late 1980`s and are now managed, operated and maintained by the Kramer Junction Company. In this paper, Sandia National Laboratories performed an analysis of the annual energy production from the five plants. Annual solar-to-electric conversion efficiencies are calculated and the major factors that influenced the results are presented. The generally good efficiencies are primarily attributed to the excellent equipment availabilities achieved at all plants.

This paper describe a system that was added to an existing satellite-borne telescope design for the purpose of compensating the boresight errors that had been observed in earlier flights of similar instruments. Those errors had been found to be caused by thermal distortion of the spaceframe. This retrofit design was subject to severe volume restrictions because it was fitted into an already tightly-packaged instrument envelope. It was found practical to improve the basic design by converting a redundant structure into a statically-determinate one. It was also possible to use portions of the mechanical actuation system to facilitate the position encoding needed for computer interfacing.

A sinkhole was first observed in May 1992 over the outer edge of the two-tiered former salt mine that was converted for oil storage by the US Strategic Petroleum Reserve (SPR). Results of diagnostic studies which included geophysical, geochemical, drilling, and hydrological methods suggest a direct connection exists between the surface collapse area and the underground mine. The connection was confirmed by correlative measurements of sediment slump rates, piezometric surface deflection, and brine influx rates into the mine. The dissolution of salt below the sinkhole that initiated the leak into the mine was likely caused by several confluent geologic processes, and exacerbated by mining-induced stresses that created fractures which severed as hydrologic flowpaths. Modeling studies of mine stresses show that years of tensional stresses may be required before cracking begins to occur, but once begun can continue to develop, and relieve the stress in that specific regime. The crack regime creates the avenue for incursion of groundwater, very slowly initially, but gradually enlarging as undersaturated groundwater dissolves salt on the sides of the crack. Mitigative measures include increasing the mine pressurization, slowing the dissolution by injecting brine into the sinkhole throat, and permeation grouting in hydrologic flowpaths.

The intent of the WIPP, being constructed in the bedded geologic salt deposits of Southeastern New Mexico, is to provide the technological basis for the safe disposal of radioactive Transuranic (TRU) wastes generated by the defense programs of the United States. In determining this technological basis, advanced reliability and structural analysis techniques are used to determine the probability of time-to-closure of a hypothetical underground shaft located in an argillaceous salt formation and filled with compacted crushed salt. Before being filled with crushed salt for sealing, the shaft provides access to an underground facility. Reliable closure of the shaft depends upon the sealing of the shaft through creep closure and recompaction of crushed backfill. Appropriate methods are demonstrated to calculate cumulative distribution functions of the closure based on laboratory determined random variable uncertainty in salt creep properties.

In a time when many companies are trying to find a way to do more with less, they are missing the ``solution`` that is right before their eyes. Rather than trying to decide on whether to reengineer or process improve, they should be focused on their most valuable resource: people. This paper discusses the elements of leadership and how it applies to all individuals in an organization. To get outstanding results from people, they need to begin by making leadership everybody`s business.

Tax loads and required revenues are estimated for current and future solar central receiver and gas-fired plants competing in the same market. An economic measure of tax equity is used to evaluate the equity of the tax loads under past and present tax codes. The same measure is used to devise a tax strategy which produces the following two types of equitable taxation: (1) the two plants carry nearly equal tax loads, and (2) local, state and federal governments receive the same distribution of revenues from the solar plant as from the gas-fired plant `Me results show that central receivers (and likely other capital-intensive technologies) carry higher tax loads compared to competing gasfired generation, that tax loads are highly correlated with competitiveness, and that equitable taxation is feasible within the boundaries of the study.

Recent Sandia support of the Solar Two project has included the analysis of optical performance issues related to heliostat field improvements. Two types of heliostats will be used for the Solar Two project: The 1818 original 38.4 m{sup 2} Martin Marietta Co. heliostats, and 108 new 95 m{sup 2} Lugo heliostats. Carrisa Plains mirror modules will be used to construct the Lugo heliostats and refurbish original heliostats. Baseline, clean reflectivity measurements of 0.90 and 0.94 are recomended for the original heliostat and the Carrisa Plains modules, respectively. Sandia`s Beam Characterization System provided beam quality information for representative configurations of both heliostats. This showed that the replacement of two facets with Carrisa Plains modules on an original heliostat led to a slight increase in spillage, but also increased beam power. As expected, the large beam of the Lugo heliostat showed poorer beam quality and significant spillage, but proved to be an economical addition of reflective area. The Carrisa Plains modules were found to be nominally flat, although the focal length changed slightly with temperature. An analysis of the canting options for both types of heliostats was performed. It was recommended the original heliostats be canted with an on-axis, lookback method, whereas a two-step method using first on-, then off-axis approaches was recommended for the Lugo heliostats. Finally, measurements performed at the Daggett site showed that despite the 1992 Landers earthquake, heliostat pedestal tilt and the associated tracking errors are expected to be within acceptable limits.

Reflux heat-pipe receivers have been identified as a desirable interface to couple a Stirling-cycle engine with a parabolic dish solar concentrator. The reflux receiver provides power nearly isothermally to the engine heater heads while decoupling the heater head design from the solar absorber surface design. The independent design of the receiver and engine heater head leads to higher system efficiency. Heat pipe reflux receivers have been demonstrated at approximately 65 kW{sub t} power throughput. Several 25 to 30-kW{sub e} Stirling-cycle engines are under development, and will soon be incorporated in commercial dish-Stirling systems. These engines will require reflux receivers with power throughput limits reaching 90-kW{sub t}. The extension of heat pipe technology from 60 kW{sub t} to 100 kW{sub t} is not trivial. Current heat pipe wick technology is pushed to its limits. It is necessary to develop and test advanced wick structure technologies to perform this task. Sandia has developed and begun testing a Bekaert Corporation felt metal wick structure fabricated by Porous Metal Products Inc. This wick is about 95% porous, and has liquid permeability a factor of 2 to 8 times higher than conventional technologies for a given maximum pore radius. The wick has been successfully demonstrated in a bench-scale heat pipe, and a full-scale on-sun receiver has been fabricated. This report details the wick design, characterization and installation into a heat pipe receiver, and the results of the bench-scale tests are presented. The wick performance is modeled, and the model results are compared to test results.

The ecological risk assessment process in its ideal form is an unbiased approach for assessing the probability of harm to the environment as a consequence of a given action. This information can then be combined with other societal values and biases in the management of such risks. However, as the process currently is understood, decision makers often are accused of manipulating information in order to generate decisions or achieve buy in from the public in support of a particular political agenda. A clear understanding of the nature of the risk management process can help define areas where information should be free from social or personal bias, and areas where values and judgments are critical. The authors do not propose to discuss the individual`s decision-making process, but rather to address the social process of risk communication and environmentally-related decision-making, identifying which parts of that process require bias-free, scientifically generated information about the consequences of various actions and which parts need an understanding of the social values which underlie the informed choices among those possible actions.

Mass transport properties are important in polycrystalline materials used as protective films. Traditionally, such properties have been studied by examining model polycrystalline structures, such as a regular array of straight grain boundaries. However, these models do not account for a number of features of real grain ensembles, including the grain size distribution and variations in grain shape. In this study, a finite difference scheme is developed to study transient and steady-state mass transport through realistic two dimensional polycrystalline microstructures. Comparisons with the transport properties of traditional model microstructures provide regimes of applicability of such models. The effects of microstructural parameters such as average grain size are examined.

As Sandia National Laboratories and the Physical and Chemical Sciences Center develop an increasingly diverse set of customers, research partners, and Cooperative Research and Development Agreements (CRADA`s) with industry, there is a need for providing more concise information describing the technical achievements and capabilities. This publication, Research Briefs, is designed to inform the present and potential partners in research and technology advancement. The research emphasizes semiconductor physics, electronic materials, surface physics and chemistry, plasma and chemical processing sciences, lasers and optics, vision science, ion-solid interactions and defect physics, and advanced materials physics. The specific programs pursued are driven by the research goals which are greatly influenced by interactions with the government and industrial customers.

The peak thermal power generated in microelectronics assemblies has risen from less than 1 W/cm{sup 2} in 1980 to greater than 40 W/cm{sup 2} today, due primarily to increasing densities at both the IC and packaging levels. The authors have demonstrated enhanced heat transfer in a prototype Si substrate with a backside micro heat channel structure. Unlike conventional micro heat pipes, these channels are biaxial with a greater capacity for fluid transfer. Thermal modeling and preliminary experiments have shown an equivalent increase in substrate thermal conductivity to over 500 W/m{center_dot}K, or a four times improvement. Optimization of the structure and alternative liquids will further increase the thermal conductivity of the micro heat channel substrate with the objective being polycrystalline diamond, or about 1,200 W/m{center_dot}K. The crucial design parameters for the micro heat channel system and the thermal characteristics of the system will be covered.

More than 300 sinkholes, fissures, depressions, and other collapse features occur along a 70 km (45 mi) dissolution front of the Permian Supai Formation, dipping northward into the Holbrook Basin, also called the Supai Salt Basin. The dissolution front is essentially coincident with the so-called Holbrook Anticline showing local dip reversal; rather than being of tectonic origin, this feature is likely a subsidence-induced monoclinal flexure caused by the northward migrating dissolution front. Three major areas are identified with distinctive attributes: (1) The Sinks, 10 km WNW of Snowflake, containing some 200 sinkholes up to 200 m diameter and 50 m depth, and joint controlled fissures and fissure-sinks; (2) Dry Lake Valley and contiguous areas containing large collapse fissures and sinkholes in jointed Coconino sandstone, some of which drained more than 50 acre-feet ({approximately}6 {times} 10{sup 4} m{sup 3}) of water overnight; and (3) the McCauley Sinks, a localized group of about 40 sinkholes 15 km SE of Winslow along Chevelon Creek, some showing essentially rectangular jointing in the surficial Coconino Formation. Similar salt karst features also occur between these three major areas. The range of features in Supai salt are distinctive, yet similar to those in other evaporate basins. The wide variety of dissolution/collapse features range in development from incipient surface expression to mature and old age. The features began forming at least by Pliocene time and continue to the present, with recent changes reportedly observed and verified on airphotos with 20 year repetition. The evaporate sequence along interstate transportation routes creates a strategic location for underground LPG storage in leached caverns. The existing 11 cavern field at Adamana is safely located about 25 miles away from the dissolution front, but further expansion initiatives will require thorough engineering evaluation.

We performed neutron powder diffraction on solution-derived lead zirconate titanates (PZT). Three compositions, PZT 45/55, PZT 20/80 and PbTiO{sub 3}, were investigated. The materials were annealed so that the perovskite phase had just begun to grow from the precursor phase. In our materials this precursor phase is the pyrochlore rather than fluorite phase. The results show that in the pyrochlore phase, the (Ti,Zr) and the Pb are ordered in their crystallographic sites while the O are essentially disordered in both of the two usual pyrochlore anion sites.

A conversion coating method has been developed based on precipitation of Li{sub 2}[Al{sub 2}(OH){sub 6}]{sub 2}{center_dot}CO{sub 3}{center_dot}3H{sub 2}O from alkaline lithium salt solutions. The process is procedurally similar to chromate conversion coating but does not use or produce hazardous chemicals. The coating that forms is polycrystalline, continuous and conformal. The coating meets the MIL-C-5541E corrosion resistance, electrical contact resistance and paint adhesion requirements for certain aluminum alloys, but does not match the levels of performance exhibited by chromate conversion coatings. In this paper, methods for producing the coating are described. Corrosion resistance has been characterized using electrochemical impedance spectroscopy and salt spray exposure. The structural, compositional and property changes attending post-coating thermal exposure are discussed. Performance in standardized corrosion, electrical and paint adhesion tests is also presented.

Hexylene-bridged polysilsesquioxanes can be prepared as mesoporous or non-porous xerogels simply by switching from basic to acidic polymerization conditions. In this study, we looked at the effect of monomer concentration on porosity of hexylene-bridged xerogels prepared under acidic and basic conditions. 1, 6-Hexylene-bridged polysilsesquioxanes were prepared by sol-gel polymerizations of 1, 6-bis(triethoxysilyl)hexane 1 with concentrations between 0. 1 to 1.2 M in ethanol. Gelation times ranged from seconds for 1.2 M concentration to months for 0.2 M. The gels were processed into xerogels by an aqueous work-up and the dry gels characterized by scanning electron microscopy (SEM), solid state {sup 13}C and {sup 29}Si CP MAS NMR spectroscopy, and gas sorption porosimetry.

Hydrocarbon-bridged polysilsesquioxanes are prepared by the sol-gel polymerization of monomers with more than one trialkoxysilyl group attached directly to the bridging group by Si-C bonds. While the effects of varying the identity of the bridging group (length, rigidity, etc.), monomer concentration, and type of catalyst have been studied, the effect of different alkoxy ligands on the silicon atoms has not been investigated. For this study, 1, 6-- bis(triethoxysilyl)hexane 1 and 1, 6-bis(trimethoxysilyl)hexane 2 were polymerized under acidic and basic conditions in ethanol and methanol, respectively, and in tetrahydrofuran (THF). The resulting gels were processed to afford xerogels that were characterized by SEM, solid state {sup 13}C and {sup 29}Si Cross Polarization Magic Angle Spinning (CP MAS) NMR spectroscopy, and nitrogen sorption porosimetry.

The flat panel display development activities underway at Sandia National Laboratories are described. Research is being conducted in the areas of glass substrates, phosphors, large area processes, and electron emissions. Projects are focused on improving process yield, developing large area processes, and using modeling techniques to predict design performance.

Optical prossesses in nanostructured fractal composites are shown to be strongly enhanced. The enhancement occurs because of a localization of dipolar eigenmodes in subwavelength areas.

I{sub DDQ} testing of CMOSICs is a technique for production quality and reliability improvement, design validation, and failure analysis. The origin and basic concepts of I{sub DDQ} testing are reviewed. The relationship of I{sub DDQ} testing to other test methods is considered in the context of the whole IC life cycle from design, fabrication, and test through end use. A comprehensive test strategy is described that uses defect classes based on defect electrical properties rather than traditional fault models.

Despite intensive efforts in the area of dynamic graph algorithms, no efficient algorithms are known for the dynamic versions of some basic graph problems such as strong connectivity and transitive closure. We provide some explanation for this lack of success by presenting quadratic lower bounds on the strong certificate complexity of such problems, thereby establishing the inapplicability of the only known general technique for designing dynamic graph algorithms, viz., sparsification. These results also provide evidence of the inherent intractability of such dynamic graph problems. Some of our results are based on a general technique for obtaining lower bounds on the strong certificate complexity for a class of graph properties by establishing a relationship with the witness complexity. In many real applications of dynamic graph problems, a certain amount of lookahead is available. Specifically, we consider the problems of assembly planning in robotics and the maintenance of relations in databases which, respectively, give rise to dynamic strong connectivity and transitive closure. We exploit the (naturally available) lookahead in these two applications to circumvent the inherent complexity of the dynamic graph problems. We propose a variant of sparsification, viz., lookahead based sparsification, and apply it to obtain the first efficient fully dynamic algorithms for strong connectivity and transitive closure.

The photo-destruction of the high explosives HMX, RDX and TNT was investigated using two systems (ozone versus titanium dioxide), two reactors (pot vs annular reactor), and two types of lamps (1000 Watt Hg-Xe vs 25 Watt LP Hg). A mass balance was performed on reactions executed under pseudo-solar conditions, and relative reaction rates and products were compared for ozone and titanium dioxide based processes. The ratios of relative product formation is also discussed. Results show that there was little difference in the reactions performed in the annular reactor when either ozone or titanium oxide were used. The chemistry of RDX and HMX are very similar, as expected. Future work involving the mechanism is also discussed.