Publications

Understanding the mechanisms of growth during vapor-phase deposition is critical for the precise control of surface morphology required by advanced electronic device structures. Yet only relatively recently have the tools for observing this growth on an atomic-level scale become available (via scanning tunneling microscopy (STM), reflection high energy electron diffraction (RHEED) and low-energy electron microscopy (LEEM)). We present results from our own RHEED and STM measurements in which we use computer simulations to aid in determining the fundamental surface processes which contribute to.the observed structures. In this study of low-energy ion bombardment and growth on Si(001), it is demonstrated how simulations enable us to determine the dominant atomistic process.

Reflective Particle Tags were developed for uniquely identifying individual strategic weapons that would be counted in order to verify arms control treaties. These tags were designed to be secure from copying and transfer even after being lift under the control of a very determined adversary for a number of years. This paper discusses how this technology can be applied in other applications requiring confidence that a piece of equipment, such as a seal or a component of a secure, has not been replaced with a similar item. The hardware and software needed to implement this technology is discussed, and guidelines for the sign of systems that rely on these or similar randomly formed features for security applications are presented. Substitution of identical components is one of the easiest ways to defeat security seals, secure containers, verification instrumentation, and similar equipment. This technology, when properly applied, provides a method to counter this defeat scenario. This paper presents a method for uniquely identifying critical security related equipment. Guidelines for implementing identification systems based on reflective particles or similar random features without compromising their intrinsic security are discussed.

A non-contact, high-resolution laser ranging device has been incorporated into an instrument for accurately mapping the surface of WECS airfoils in the field. Preliminary scans of composite materials and bug debris show that the system has adequate resolution to accurately map bug debris and other surface contamination. This system, just recently delivered and now being debugged and optimized, will be used to characterize blade surface contamination on wind turbines. The technology used in this system appears to hold promise for application to many other measurements tasks, including a system for quickly and very accurately determining the profile of turbine blade molds and blades.

Sandia National Laboratories has completed the design and is now fabricating packages for shipment of tritium gas in conformance with 10 CFR 71. The package, referred to as the AL-SX, is quite unique in that its contents are a radioactive gas, and a large margin of safety has been demonstrated through overtesting. The AL-SX is small, 42 cm in diameter and 55 cm tall, and weighs between 55 kg empty and up to a maximum of 60 kg with contents and is designed for a 20-year service life. This paper describes the design of the AL-SX and certification testing performed on AL-SX packages and discusses containment of tritium and AL-SX manufacturing considerations.

Sandia National Laboratories is one of the nation's largest research and development (R and D) facilities and is responsible for national security programs in defense and energy with a primary emphasis on nuclear weapon R and D. However, Sandia also supports a wide variety of projects ranging from basic materials research to the design of specialized parachutes. As a multiprogram national laboratory, Sandia has much to offer both industrial and government customers in pursuing space nuclear technologies. A brief summary of Sandia's technical capabilities, test facilities, and example programs that relate to military and civilian objectives in space is presented.

Sandia National Laboratories is actively involved in testing coated particle nuclear fuels for the Space Nuclear Thermal Propulsion (SNTP) program managed by Phillips Laboratory. The testing program integrates the results of numerous in-pile and out-of-pile tests with modeling efforts to qualify fuel and fuel elements for the SNTP program. This paper briefly describes the capabilities of the Annular Core Research Reactor (in which the experiments are performed), the major in-pile tests, and the models used to determine the performance characteristics of the fuel and fuel elements. 6 refs.

The US Department of Energy's Slant Hole Completion Test Well, SHCT-1, was drilled in 1990 into gas-bearing, lenticular and blanket-shaped sandstones of the Mesaverde Formation, northwestern Colorado. The reservoirs are over-pressured, with sub-microdarcy, in situ, matrix-rock permeabilities. However, a set of sub-parallel natural fractures increases the whole-reservoir permeabilities, measured by well tests, to several tens of microdarcies. The slant hole azimuth was therefore oriented to cut across the dominant fracture strike, in order to access the natural-fracture permeability and increase drainage into the wellbore.

Advection-dominated flows occur widely in the transport of groundwater contaminants, the movements of fluids in enhanced oil recovery projects, and many other contexts. In numerical models of such flows, adaptive local grid refinement is a conceptually attractive approach for resolving the sharp fronts or layers that tend to characterize the solutions. However, this approach can be difficult to implement in practice. A domain decomposition method developed by Bramble, Ewing, Pasciak, and Schatz, known as the BEPS method, overcomes many of the difficulties. We demonstrate the applicability of the iterative BEPS ideas to finite-element collocation on trial spaces of piecewise Hermite bicubics. The resulting scheme allows one to refine selected parts of a spatial grid without destroying algebraic efficiencies associated with the original coarse grid. We apply the method to two dimensional time-dependent advection-diffusion problems.

Three methods of evaluating accelerated battery test data are described. Criteria for each method are used to determine the minimum test matrix required for accurate predictions. Other test methods involving high current discharge and real time techniques are discussed.

Computational mechanics simulation capability via the finite element method is being integrated into the FASTCAST project to allow realistic analyses of investment casting problems. Commercial and in-house software is being coupled to new, solid model based mesh generation capabilities to provide improved access to fluid, thermal and structural simulations. These simulations are being used for the validation of complex gating designs and the study of fundamental problems in casting.

This document presents recent accomplishments in engineering and science at Sandia National Laboratories. Commercial-scale parabolic troughs at the National Solar Thermal Test Facility are used for such applications as heating water, producing steam for industrial processes, and driving absorption air conditioning systems. Computerized-aided design, superconductor technology, radar imaging, soldering technology, software development breakthroughs are made known. Defense programs are exhibited. And microchip engineering applications in test chips, flow sensors, miniature computers, integrated circuits, and microsensors are presented.

Diffraction peaks can occur as unidentifiable peaks in the energy spectrum of an x-ray spectrometric analysis. Recently, there has been increased interest in oriented polycrystalline films and epitaxial films on single crystal substrates for electronic applications. Since these materials diffract x-rays more efficiently than randomly oriented polycrystalline materials, diffraction peaks are being observed more frequently in x-ray fluorescent spectra. In addition, micro x-ray spectrometric analysis utilizes a small, intense, collimated x-ray beam that can yield well defined diffraction peaks. In some cases these diffraction peaks can occur at the same position as elemental peaks. These diffraction peaks, although a possible problem in qualitative and quantitative elemental analysis, can give very useful information about the crystallographic structure and orientation of the material being analyzed. The observed diffraction peaks are dependent on the geometry of the x-ray spectrometer, the degree of collimation and the distribution of wavelengths (energies) originating from the x-ray tube and striking the sample.

Geologic materials are often modeled with discrete spheres because the material is not continuous and discrete spherical models simplify the mathematics. Spherical element models have been created using assemblages of spheres with a specified particle size distribution or by assuming the particles are all the same size and making the assemblage a close-packed array of spheres. Both of these approaches yield a considerable amount of material dilatation upon movement. This has proven to be unsatisfactory for sedimentary rock formations that contain bedding planes where shear movement can occur with minimal dilatation of the interface. A new concept referred to as packing angle has been developed to allow the modeler to build arrays of spheres that are the same size but have the rows of spheres offset from each other. ne row offset is a function of the packing angle and allows the modeler to control the dilatation as rows of spheres experience relative horizontal motion.

The syntheses and physical properties of {kappa}-(ET){sub 2}Cu[N(CN){sub 2}]X (X=Br and Cl) are summarized. The {kappa}-(ET){sub 2}Cu[N(CN){sub 2}]Br salt is the highest {Tc} radical-cation based ambient pressure organic superconductor ({Tc}=11.6 K), and the {kappa}-(ET){sub 2}Cu[N(CN){sub 2}]Cl salt becomes a superconductor at even higher {Tc} under 0.3 kbar hydrostatic pressure ({Tc}=12.8 K). The similarities and differences between {kappa}-(ET){sub 2}Cu[N(CN){sub 2}]Br and {kappa}-(ET){sub 2}Cu(NCS){sub 2} ({Tc}=10.4 K) are presented. The X-ray structures at 127 K reveal that the the S{hor_ellipsis}S contacts shorten between ET dimers in the former compound while the S{hor_ellipsis}S contacts shorten within dimers in the latter. The difference in their ESR linewidth behavior is also explained in terms of the structural differences. A semiconducting compound, (ET)Cu[N(CN){sub 2}]{sub 2}, isolated during {kappa}-(ET){sub 2}Cu[N(CN){sub 2}]Cl synthesis is also reported. The ESR measurements of the {kappa}-(ET){sub 2}Cu[N(CN){sub 2}]Cl salt indicate that the phase transition near 40 K is similar to the spin density wave transition in (TMTSF){sub 2}SbF{sub 6}. A new class of organic superconductors, {kappa}-(ET){sub 2}Cu{sub 2}(CN){sub 3} and {kappa}-(ET){sub 2}Cu{sub 2}(CN){sub 3}-{delta}Br{delta}, is reported with {Tc}`s of 2.8 K (1.5 kbar) and 2.6 K (1 kbar), respectively.

Nuclear weapons system designers and safety analysts are contemplating broader use of probabilistic risk assessment techniques. As an aid to their understanding, this document summarizes the development and use of probabilistic risk assessment (PRA) techniques in the nuclear power industry. This report emphasizes the use of PRA in decision making with the use of case studies. Nuclear weapon system designers and safety analysts, contemplating the broader use of PRA techniques, will find this document useful.

This document contains implementation details for the Quality Information Management System (QIMS) Pilot Project, which has been released for VAX/VMS systems using the INGRES RDBMS. The INGRES Applications-By-Forms (ABF) software development tool was used to define the modules and screens which comprise the QIMS Pilot application. These specifications together with the QIMS information model and corresponding database definition constitute the QIMS technical specification and implementation description presented herein. The QIMS Pilot Project represents a completed software product which has been released for production use. Further extension projects are planned which will release new versions for QIMS. These versions will offer expanded and enhanced functionality to meet further customer requirements not accommodated by the QIMS Pilot Project.

A large buildup in interface traps has been observed in commercial and radiation-hardened MOS transistors at very long times after irradiation (> 10{sup 6} s). This latent buildup may have important implications for CMOS response in space. 13 refs.

Translations of two pioneering Russian papers on antenna theory are presented. The first paper provides a treatise on finite-length dipole antennas; the second paper addresses infinite-length, impedance-loaded transmitting antennas.

A new approach for solving two-dimensional clustering problems is presented. The method is based on an inhibitory template which is applied to each pair of dots in a data set. Direct clustering of the pair is inhibited (allowed) if another dot is present (absent), respectively, within the area of the template. The performance of the method is thus entirely determined by the shape of the template. Psychophysical experiments have been used to define the template shape for this work, so that the resulting method requires no pattern-dependent adjustment of any parameters. The novel concept of a psychophysically-defined template and the absence of adjustable parameters set this approach apart from previous work. The useful grouping performance of this approach is demonstrated with the successful grouping of a variety of dot patterns selected from the clustering literature.

Sandia National Laboratories (SNL) Environmental Restoration (ER) Program has recently implemented a highly structured CS{sup 2} required by DOE. It is a complex system which has evolved over a period of a year and a half. During the implementation of this system, problem areas were discovered in cost estimating, allocation of management costs, and integration of the CS{sup 2} system with the Sandia Financial Information System. In addition to problem areas, benefits of the system were fund in the areas of schedule adjustment, projecting personnel requirements, budgeting, and responding to audits. Finally, a number of lessons were learned regarding how to successfully implement the system.

Ferroelectric PZT 53:47 thin films were prepared by two different solution deposition methodologies. Both routes utilized carboxylate and alkoxide precursors and acetic acid, which served as both a solvent and a chemical modifier. We have studied the effects of solution preparation conditions on film microstructure and ferroelectric properties, and have used NMR spectroscopy to characterize chemical differences between the two precursor solutions. Films prepared by a sequential precursor addition (SPA) process were characterized by slightly lossy hysteresis loops, with a P{sub r} of 18.7 {mu}C/cm{sup 2} and an E{sub c} of 55.2 kV/cm. Films prepared by an inverted mixing order (IMO) process were characterized by well saturated hysteresis loops, a P{sub r} of 26.2 {mu}C/cm{sup 2} and an E{sub c} of 43.3 kV/cm. While NMR investigations indicated that the chemical environments of both the proton and carbon species were similar for the two processes, differences in the amounts of by-products (esters, and therefore, water) formed were noted. These differences apparently impacted ceramic microstructure. Although both films were characterized by a columnar growth morphology, the SPA derived film displayed a residual pyrochlore layer at the film surface, which did not transform into the stable perovskite phase. The presence of this layer resulted in poor dielectric properties and lossy ferroelectric behavior.

We have developed a video detection algorithm for measuring the residue left on a printed circuit board after a soldering process. Oblique lighting improves the contrast between the residue and the board substrate, but also introduces an illumination gradient. The algorithm uses the Boundary Contour System/Feature Contour System to produce an idealized clean board image by discounting the illuminant, detecting trace boundaries, and filling the trace and substrate regions. The algorithm then combines the original input image and ideal image using mathematical models of the normal and inverse Weber Law to enhance the residue on the traces and substrate. The paper includes results for a clean board and one with residue.

CEPXS/ONELD is a discrete ordinates transport code package that can model the electron-photon cascade from 100 MeV to 1 keV. The CEPXS code generates fully-coupled multigroup-Legendre cross section data. This data is used by the general-purpose discrete ordinates code, ONELD, which is derived from the Los Alamos ONEDANT and ONETRAN codes. Version 1.0 of CEPXS/ONELD was released in 1989 and has been primarily used to analyze the effect of radiation environments on electronics. Version 2.0 is under development and will include user-friendly features such as the automatic selection of group structure, spatial mesh structure, and S{sub N} order.

Changing the focus of a corporate compensation and performance review system from process orientation to data base orientation results in a more integrated and flexible design. Data modeling of the business system provides both systems and human resource professionals insight into the underlying constants of the review process. Descriptions of the business and data modeling processes are followed by a detailed presentation of the data base model. Benefits derived from designing a system based on the model include elimination of hard-coding, better audit capabilities, a consistent approach to exception processing, and flexibility of integrating changes in compensation policy and philosophy.

This paper will address the purpose, scope, and approach of the Department of Energy Tiger Team Assessments. It will use the Tiger Team Assessment experience of Sandia National Laboratories at Albuquerque, New Mexico, as illustration.

One of the common waste streams generated throughout the nuclear weapon complex is hardware'' originating from the nuclear weapons program. The activities associated with this hardware at Sandia National Laboratories (SNL) include design and development, environmental testing, reliability and stockpile surveillance testing, and military liaison training. SNL-designed electronic assemblies include radars, arming/fusing/firing systems, power sources, and use-control and safety systems. Waste stream characterization using process knowledge is difficult due to the age of some components and lack of design information oriented towards hazardous constituent identification. Chemical analysis methods such as the Toxicity Characteristic Leaching Procedure (TCLP) are complicated by the inhomogeneous character of these components and the fact that many assemblies have aluminum or stainless steel cases, with the electronics encapsulated in a foam or epoxy matrix. In addition, some components may contain explosives, radioactive materials, toxic substances (PCBs, asbestos), and other regulated or personnel hazards which must be identified prior to handling and disposal. In spite of the above difficulties, we have succeeded in characterizing a limited number of weapon components using a combination of process knowledge and chemical analysis. For these components, we have shown that if the material is regulated as RCRA hazardous waste, it is because the waste exhibits one or more hazardous characteristics; primarily reactivity and/or toxicity (Pb, Cd).

The discrete Fourier transform and power spectral density are often used in analyzing data from analog-to-digital converters. These analyses normally apply a window to the data to alleviate the effects of leakage. This paper describes how windows modify the magnitude of a discrete Fourier transform and the level of a power spectral density computed by Welch's method. For white noise, the magnitude of the discrete Fourier transform at a fixed frequency has a Rayleigh probability distribution. For sine waves with an integer number of cycles and quantization noise, the theoretical values of the amplitude of the discrete Fourier transform and power spectral density are calculated. We show how the signal-to-noise ratio in a single discrete Fourier transform or power spectral density frequency bin is related to the normal time-domain definition of the signal-to-noise ratio. The answer depends on the discrete Fourier transform length, the window type and the function averaged.

The UNIX LANs in 1500 are experiencing explosive growth. The individual departments are creating LANs to address their particular needs; however, at the same time, shared software tools between the departments are becoming more common. It is anticipated that users will occasionally need access to various department software and/or LAN services, and that support personnel may carry responsibilities which require familiarization with multiple environments. It would be beneficial to users and support personnel if the various department environments share some basic similarities, allowing somewhat transparent access. This will become more important when departments share specific systems, as 1510 and 1550 have proposed with an unclassified UNIX system. Therefore, standards/conventions on the department LANs and the central site systems have to be established to allow for these features. it should be noted that the goal of the UEC is to set standards/conventions which affect the users and provide some basic structure for software installation and maintenance; it is not the intent that all 1500 LANs be made identical at an operating system and/or hardware level. The specific areas of concern include: (1) definition of a non-OS file structure; (2) definition of an interface for remote mounted file systems; (3) definition of a user interface for public files; (4) definition of a basic user level environment; and (5) definition of documentation requirements for public files (shared software). Each of these areas is addressed in this paper.

This document contains implementation details for the Sandia Management Restructure Study Team (MRST) Prototype Information System, which resides on a Sun SPARC II workstation employing the INGRES RDBMS. The INGRES/Windows 4GL application editor was used to define the components of the two user applications which comprise the system. These specifications together with the MRST information model and corresponding database definition constitute the MRST Prototype Information System technical specification and implementation description presented herein. The MRST Prototype Information System represents a completed software product which has been presented to the Management Restructure Study Team to support the management restructing processes at Sandia National Laboratories.

Finite element analyses of oil-filled caverns were performed to investigate the effects of cavern depth on surface subsidence and storage loss, a primary performance criteria of SPR caverns. The finite element model used for this study was axisymmetric, approximating an infinite array of caverns spaced at 750 ft. The stratigraphy and cavern size were held constant while the cavern depth was varied between 1500 ft and 3000 ft in 500 ft increments. Thirty year simulations, the design life of the typical SPR cavern, were performed with boundary conditions modeling the oil pressure head applied to the cavern lining. A depth dependent temperature gradient of 0.012{degrees}F/ft was also applied to the model. The calculations were performed using ABAQUS, a general purpose of finite element analysis code. The user-defined subroutine option in ABAQUS was used to enter an elastic secondary creep model which includes temperature dependence. The calculations demonstrated that surface subsidence and storage loss rates increase with increasing depth. At lower depths the difference between the lithostatic stress and the oil pressure is greater. Thus, the effective stresses are greater, resulting in higher creep rates. Furthermore, at greater depths the cavern temperatures are higher which also produce higher creep rates. Together, these factors result in faster closure of the cavern. At the end of the 30 year simulations, a 1500 ft-deep cavern exhibited 4 percent storage loss and 4 ft of subsidence while a 3000 ft-deep cavern exhibited 33 percent storage loss and 44 ft of subsidence. The calculations also demonstrated that surface subsidence is directly related to the amount of storage loss. Deeper caverns exhibit more subsidence because the caverns exhibit more storage loss. However, for a given amount of storage loss, nearly the same magnitude of surface subsidence was exhibited, independent of cavern depth.

This economic analysis compares human and robotic TRUPACT unloading at the Waste Isolation Pilot Plant. Robots speed up the unloading process, reduce human labor requirements, and reduce human exposure to radiation. The analysis shows that benefit/cost ratios are greater than one for most cases using government economic parameters. This suggests that robots are an attractive option for the TRUPACT application, from a government perspective. Rates of return on capital investment are below 15% for most cases using private economic parameters. Thus, robots are not an attractive option for this application, from a private enterprise perspective.

This paper summarizes the results of aging, condition monitoring, and accident testing of Class 1E cables used in nuclear power generating stations. Three sets of cables were aged for up to 9 months under simultaneous thermal ({approximately}100{degrees}C) and radiation ({approximately}0.10 kGy/hr) conditions. After the aging, the cables were exposed to a simulated accident consisting of high dose rate irradiation ({approximately}6 kGy/hr) followed by a high temperature steam (up to 400{degrees}C) exposure. A fourth set of cables, which were unaged, was also exposed to the accident conditions. The cables that were aged for 3 months and then accident tested were subsequently exposed to a high temperature steam fragility test (up to 400{degrees}C), while the cables that were aged for 6 months and then accident tested were subsequently exposed to a 1000-hour submergence test in a chemical solution. The results of these tests do not indicate any reason to believe that many popular nuclear power plant cable products cannot inherently be qualified for 60 years of operation for conditions simulated by this testing. Mechanical measurements (primarily elongation, modulus, and density) are more effective than electrical measurements for monitoring age-related degradation. In the high temperature steam test, ethylene propylene rubber (EPR) cable materials generally survived to higher temperatures than crosslinked polyolefin (XLPO) cable materials. In dielectric testing after the submergence testing, the XLPO materials performed better than the EPR materials.

This paper describes several different types of constraints that can be placed on multilayered feedforward neural networks which are used for automatic target recognition (ATR). We show how unconstrained networks are likely to give poor generalization on the ATR problem. We also show how the ATR problem requires a special type of classifier called a one-class classifier. The network constraints come in two forms: architectural constraints and learning constraints. Some of the constraints are used to improve generalization, while others are incorporated so that the network will be forced to perform one-class classification. 14 refs

Foams, like most highly structured fluids, exhibiting rheological behavior that is both fascinating and complex. We have developed microrheological models for uniaxial extension and simple shearing flow of a dry', perfectly ordered, three-dimensional foam composed of thin films with uniform surface tension T and negligible liquid content. We neglect viscous flow in the thin films and examine large elastic-plastic deformations of the foam. The primitive undeformed foam structure is composed of regular space-filling tetrakaidecahedra, which have six square and eight hexagonal surfaces. This structure possesses the film-network topology that is necessary to satisfy equilibrium: three films meet at each edge, which corresponds to a Plateau border, and four edges meet at vertex. However, to minimize surface energy, the films must meet at equal angles of 120{degrees} and the edges must join at equal tetrahedral angles of cos{sup {minus}1}({minus}1/3) {approx} 10.947{degree}. No film in an equilibrium foam structure can be a planar polygon because no planar polygon has all angles equal to the tetrahedral edge. In the equilibrium foam structure known as Kelvin's minimal tetrakaidecahedron, the squares' are planar quadrilateral surfaces with curved edges and the hexagons' are non-planar saddle surfaces with zero mean curvature. As the foam structure evolves with the macroscopic flow, each film maintains zero mean curvature because the pressure is the same in every bubble. In general, the shape of each thin film, defined by z = h(x,y), satisfies R{sub 1}/1 + R{sub 2}/1 = {del}{center dot} (1 + {vert bar}{del}h{vert bar}){sup {1/2}} = O where R{sub 1}{sup {minus}1} and A{sub 2}{sup {minus}1} are the principal curvatures. The appropriate boundary conditions correspond to three films meeting at equal angles. For the homogeneous deformations under consideration, the center of each film moves affinely with the flow. 5 refs

We have measured the atmospheric isoplanatic angle in the near infrared by correlating widely separated time-resolved stellar images.

Renewable energy technologies convert naturally occurring phenomena into useful energy forms. These technologies use resources that generally are not depleted, such as the direct energy (heat and light) from the sun and the indirect results of its impact on the earth (wind, falling water, heating effects, plant growth), gravitational forces (the tides), and the heat of the Earth's core (geothermal), as the sources from which they produce useful energy. These very large stores of natural energy represent a resource potential that is incredibly massive -- dwarfing that of equivalent fossil energy resources. The magnitude of these resources is, therefore, not a key constraint on energy production. However, they are generally diffuse and not fully accessible, some are intermittent, and all have distinct regional and local variability. It is these aspects of their character that give rise to difficult, but generally solvable, technical, institutional, and economic challenges inherent in development and use of renewable energy resources. This report discusses the technologies and their associated energy source.

Theoretical models have been formulated describing the dynamic behavior of the swelling and contracting of polyelectrolyte gels. This paper presents a method of weighted residuals approach to solving the governing system of equations by finite element analysis. The modulation of the imbibition of solvent by a spherical gel is studied.

There is considerable interest in the use of chemically vapor deposited (CVD) polycrystalline diamond films in advanced materials technology. However, most of the potential applications of CVD diamond films require well-controlled properties which depend on the film structure, and in turn, on the conditions under which the films are synthesized. The structure of the vapor-deposited diamond films is frequently characterized by Raman spectroscopy. Despite extensive research, much work still needs to be completed to understand the various features of the Raman spectra and to understand how the processing variables affect the spectral features. This paper examines the Raman spectra of diamond films prepared by a hot-filament-assisted CVD process as a function of substrate processing and deposition parameters.

Many applications of national importance require the design, analysis, and simulation of complex electromagnetic phenomena. These applications range from the simulation of synthetic aperture radar to the design and analysis of low-observable platforms, antenna design, and automatic target recognition. In general, the modeling of complex electromagnetic phenomena requires significant amounts of computer time and capacity on conventional vector supercomputers but takes far less on massively parallel computers. Sandia National Laboratories is currently developing massively parallel methods and algorithms for the characterization of complex electromagnetic phenomena. The goal of on going research at Sandia is to understand the characteristics, limitations, and trade-offs associated with complex electromagnetic systems including: modeling the seeker response to complex targets in clutter, calculating the radiation and scattering from conformal communication and radar system antennas, and the analysis and design of high speed circuitry. By understanding the theoretical underpinnings of complex electromagnetic systems it is possible to achieve realistic models of system performance. The first objective is the development of computationally practical, high fidelity, systems models targeted for massively parallel computers. Research to achieve this objective is conducted in such areas as mathematical algorithms, problem decomposition, inter-processor communication schemes, and load balancing. The work in mathematical algorithms includes both the development of new methods and the parallel implementation of existing techniques. The second objective is the application of these high fidelity models to facilitate a better understanding of systems level performance for many C{sup 3}I platforms. This presentation describes applications of much current interest and novel solution techniques for these applications utilizing massively parallel processing techniques.

A neighboring external control problem is formulated for a hypersonic glider to execute a maximum-terminal-velocity descent to a stationary target. The resulting two-part, feedback control scheme initially solves a nonlinear algebraic problem to generate a nominal trajectory to the target altitude. Secondly, a neighboring optimal path computation about the nominal provides a lift and side-force perturbations necessary to achieve the target downrange and crossrange. On-line feedback simulations of the proposed scheme and a form of proportional navigation are compared with an off-line parameter optimization method. The neighboring optimal terminal velocity compares very well with the parameter optimization solution and is far superior to proportional navigation. 8 refs.

This paper describes the design of an inverse adaptive filter, using the Least-Mean-Square (LMS) algorithm, the correct data taken with an analog filter. The gradient estimate used in the LMS algorithm is based upon the instantaneous error, e{sup 2}(n). Minimizing the mean-squared-error does not provide an optimal solution in this specific case. Therefore, another performance criterion, error power, was developed to calculate the optimal inverse model. Despite using a different performance criterion, the inverse filter converges rapidly and gives a small mean-squared-error. Computer simulations of this filter are also shown in this paper.

Intense light ion beams are being developed to drive inertial confinement fusion (ICF) targets. Recently, intense proton beams have been used to drive two different types of targets in experiments on the Particle Beam Fusion Accelerator. The experiments focused separately on ion deposition physics and on implosion hydrodynamics. In the ion deposition physics experiments, a 3--4 TW/cm{sup 2} proton beam heated a low-density foam contained within a gold cylinder with a specific power deposition exceeding 100 TW/gm for investigating ion deposition, foam heating, and generation of x-rays. The significant results from these experiments included the following: the foam provided an optically thin radiating region, the uniformity of radiation across the foam was good, and the foam tamped the gold case, holding it in its original position for the 15 ns beam pulse width.

This document describes the Temperature Monitoring System for the RHEPP project at Sandia National Laboratories. The system is designed to operate in the presence of severe repetitive high voltage and electromagnetic fields while providing real time thermal data on component behavior. The thermal data is used in the design and evaluation of the major RHEPP components such as the magnetically switched pulse compressor and the linear induction voltage adder. Particular attention is given to the integration of commercially available hardware and software components with a custom written control program. While this document is intended to be a reference guide, it may also serve as a template for similar applications. 3 refs.

This bibliography contains 34 references concerning utilizing benchmarking in the management of businesses. Books and articles are both cited. Methods for gathering and utilizing information are emphasized. (GHH)

Measurements have recently been conducted and computer models constructed to determine the coupling of lightning energy into munition storage bunkers as detailed in companion conference papers. In this paper transfer functions from the incident current to the measured parameters are used to construct simple circuit models that explain much of the important observed quantitative and qualitative information and differences in transfer functions are used to identify nonlinearities in the response data. In particular, V{sub oc} -- the open-circuit voltage generated between metal objects in the structure, I{sub sc} -- the short-circuit current generated in a wire connecting metal objects in the structure, and a typical current measurement in the buried counterpoise system behave in a relatively simple manner explainable by one or several circuit elements. The circuit elements inferred from measured data are comparable in magnitude with those developed from simple analytical models for inductance and resistance. These analytical models are more useful in predicting bounding electromagnetic environment values rather than providing exact time domain waveforms. 2 refs.

The restoration of environmentally contaminated sites at DOE facilities has become a major effort in the past several years. The variety of wastes involved and the differing characteristics have driven the development of new restoration and monitoring technologies. One of the new remediation technologies is being demonstrated at the Savannah River Site near Aiken, South Carolina. In conjunction with this demonstration, a new technology for site characterization and monitoring of the remediation process has been applied by Sandia National Laboratories.

We used surface-profile data taken with a noncontact laser profilometer to determine the aperture distribution within a natural fracture and found the surfaces and apertures to be isotropic. The aperture distribution could be described equally well by either a normal or a lognormal distribution, although we had to adjust the standard deviation to 'fit' the data. The aperture spatial correlation varied over different areas of the fracture, with some areas being much more correlated U= others. The fracture surfaces did not have a single fractal dimension over all length scales, which implied that they were not self-similar. We approximated the saturated flow field in the fracture by solving a finite-difference discretization of the fluid-flow continuity equation in two dimensions. We then calculated tracer breakthrough curves using a particle-tracking method. comparing the breakthrough curves obtained using both coarse- and fine-resolution aperture data (0.5- and 0.05-mm spacing between points, respectively) over the same subset of the fracture domain suggests that the spacing between the aperture data points must be less than the correlation length to obtain accurate predictions of fluid flow and tracer transport. In the future, we will perform tracer experiments and numerical modeling studies to determine exactly how fine the aperture data resolution must be (relative to the correlation length) to obtain accurate predictions.

Sandia National Laboratories (SNL) designs, tests and operates a variety of accelerators that generate large amounts of high energy Bremsstrahlung radiation over an extended time. Typically groups of similar accelerators are housed in a large building that is inaccessible to the general public. To facilitate independent operation of each accelerator, test cells are constructed around each accelerator to shield it from the radiation workers occupying surrounding test cells and work-areas. These test cells, about 9 ft. high, are constructed of high density concrete block walls that provide direct radiation shielding. Above the target areas (radiation sources), lead or steel plates are used to minimize skyshine radiation. Space, accessibility and cost considerations impose certain restrictions on the design of these test cells. SNL Health Physics division is tasked to evaluate the adequacy of each test cell design and compare resultant dose rates with the design criteria stated in DOE Order 5480.11. In response SNL-Health Physics has undertaken an intensive effort to asses existing radiation shielding codes and compare their predictions against measured dose rates. This paper provides a summary of the effort underway and its results.

The last decade has offered many challenges to the welding metallurgist: new types of materials requiring welded construction, describing the microstructural evolution of traditional materials, and explaining non-equilibrium microstructures arising from rapid thermal cycle weld processing. In this paper, the author will briefly review several advancements made in these areas, often citing specific examples of where new insights were required to describe new observations, and to show how traditional physical metallurgy methods can be used to describe transformation phenomena in advanced, non-traditional materials. The paper will close with comments and suggestions as to the needs required for continued advancement in the field.

Phase II of the Long Valley Exploratory Well was completed to a depth of 7588 feet in November 1991. The drilling comprised two sub-phases: (1) drilling 17-1/2 inch hole from the Phase I casing shoe at 2558 feet to a depth of 7130 feet, plugging back to 6826 feet, and setting 13-3/8 inch casing at 6825 feet, all during August--September 1991; and (2) returning in November to drill a 3.85-inch core hole deviated out of the previous wellbore at 6868 feet and extending to 7588 feet. Ultimate depth of the well is planned to be 20,000 feet, or at a bottomhole temperature of 500{degrees}C, whichever comes first. Total cost of this drilling phase was approximately $2.3 million, and funding was shared about equally between the California Energy Commission and the Department of Energy. Phase II scientific work will commence in July 1992 and will be supported by DOE Office of Basic Energy Sciences, DOE Geothermal Division, and other funding sources.