Publications

A robust bearing estimation process for 3-component stations has been developed and explored. The method, called SEEC for Search, Estimate, Evaluate and Correct, intelligently exploits the in- herent information in the arrival at every step of the process to achieve near-optimal results. In particular, the approach uses a consistent framework to define the optimal time-frequency windows on which to make estimates, to make the bearing estimates themselves, to construct metrics helpful in choosing the better estimates or admitting that the bearing is immeasurable, andjinally to apply bias corrections when calibration information is available to yield a single final estimate. The method was applied to a small but challenging set of events in a seismically active region. The method demonstrated remarkable utility by providing better estimates and insights than previously available. Various monitoring implications are noted fiom these findings.

Oriented bicrystals of pure C11_b MoSi₂ have been grown in a tri-arc furnace using the Czochralski technique. Two single crystal seeds were used to initiate the growth. Each seed had the orientation intended for one of the grains of the bicrystals, which resulted in a 60° twist boundary on the (110) plane. Seeds were attached to a water-cooled seed rod, which was pulled at 120 mm/h with the seed rod rotating at 45 rpm. The water- cooled copper hearth was counter-rotated at 160 rpm. Asymmetric growth ridges associated with each seed crystal were observed during growth and confirmed the existence of a bicrystal. It was also found that careful alignment of the seeds was needed to keep the grain boundary from growing out of the boule. The resulting boundary was characterized by imaging and crystallographic techniques in a scanning electron microscope. The boundary was found to be fairly sharp and the misorientation between the grains remained within 2° from the disorientation between the seeds.

This paper discusses a new technique for measuring the impedance response of thickness shear mode (TSM) resonators used as fluid monitors and chemical sensors. The technique simulates the swept frequency measurements performed by an automatic network analyzer (ANA), determining the complex reflection scattering parameter, S1l, from single port devices. Unlike oscillator circuits most often used with TSM resonators, narrowband spectral measurements are not limited by cable capacitance between resonator and oscillator allowing placement of the sensor in severe environments. Only noise produced by long cable lengths limits performance and sensor sensitivity. This new technique utilizes a simple swept frequency source operating near the crystal resonance, a unique directional coupler to provide the reference and reflected RF signals, an I & Q demodulation circuit that returns two dc voltages, and computational algorithms for determining sensor response parameters. Performance, has been evaluated by comparing TSM resonator responses using this new technique to those from a commercial ANA.

The Instrumentation and Telemetry Departments at Sandia National Laboratories have been instrumenting earth penetrators for over thirty years. Recorded acceleration data is used to quantify penetrator performance. Penetrator testing has become more difficult as desired impact velocities have increased. This results in the need for small-scale test vehicles and miniature instrumentation. A miniature recorder will allow penetrator diameters to significantly decrease, opening the window of testable parameters. Full-scale test vehicles will also benefit from miniature recorders by using a less intrusive system to instrument internal arming, fusing, and firing components. This single channel concept is the latest design in an ongoing effort to miniaturize the size and reduce the power requirement of acceleration instrumentation. A micro-controller/memory based system provides the data acquisition, signal conditioning, power regulation, and data storage. This architecture allows the recorder, including both sensor and electronics, to occupy a volume of less than 1.5 cubic inches, draw less than 200mW of power, and record 15kHz data up to 40,000 gs. This paper will describe the development and operation of this miniature acceleration recorder.

To meet challenging constraints on telemetry system weight and volume, a custom Light-Weight Instrumentation System was developed to collect vehicle environment and dynamics on a short-duration exo-atmospheric flight test vehicle. The total telemetry system, including electronics, sensors, batteries, and a 1 watt transmitter weighs about 1 kg. Over 80 channels of measurement, housekeeping, and telemetry system diagnostic data are transmitted at 128 kbps. The microcontroller-based design uses the automotive industry standard Controller Area Network to interface with and support in-flight control fimctions. Operational parameters are downloaded via a standard asynchronous serial communications intefiace. The basic design philosophy and functionality is described here.

Experimentation in transparent fractures where light transmission techniques are used to measure aperture, dye concentration, and phase distribution fields can enhance our understanding of single and multi-phase flow and transport. Here, we evaluate and improve the method for aperture field measurement in transparent analog fractures and replicas of natural fractures. The primary sources of error in the measurements are: signal noise (both temporal and spatial) from the charge-coupled-device (CCD) used to measure light intensities transmitted through the fracture; non-linearity of light absorbance of the dyed solution used to fill the fracture; and refraction of light passing through the fracture. We find that each of these error sources can be minimized to optimize precision and accuracy. Our measurements of the aperture field of a -150 x 300 mm analog test fracture at a spatial resolution of 0.159 x 0.159 mm ( 2x10⁶ points) demonstrate a root-mean- square error over the field of O.9% (0.002 mm) of the mean aperture (0.222 mm). Though the results presented here are specific to our test fracture and measurement system, the general approach can be applied to other digital imaging techniques based on energy absorbance.

This report documents the assessment of performance and design of a 250-kW prototype battery energy storage system developed by Omnion Power Engineering Company and tested by Pacific Gas and Electric Company, both in collaboration with Sandia National Laboratories. The assess- ment included system performance, operator interface, and reliability. The report also discusses how to detect failed battery strings with strategically located voltage measurements.

Two major studies, one sponsored by the U.S. Department of Energy and the other by the U.S. Nuclear Regulatory Commission, were conducted in the late 1970s and early 1980s to provide information and source terms for an optimally successful act of sabotage on spent fuel casks typical of those available for use. This report applies the results of those studies and additional analysis to derive potential source terms for certain classes of sabotage events on spent fuel casks and spent fuel typical of those which could be shipped in the early decades of the 21st century. In addition to updating the cask and spent fuel characteristics used in the analysis, two release mechanisms not included in the earlier works were identified and evaluated. As would be expected, inclusion of these additional release mechanisms resulted in a somewhat higher total release from the postulated sabotage events. Although health effects from estimated releases were addressed in the earlier study conducted for U.S. Department of Energy, they have not been addressed in this report. The results from this report maybe used to estimate health effects.

This document details the instructional design and delivery methods for a course on the NWC Technical Business Practices that are used to enact configuration management of Nuclear Weapons Product and Equipment.

Subsurface barriers are being constructed at both government and private sites to control hazardous material migration. The Department of Energy, in particular, is developing new barrier construction methods and materials for applications in saturated and unsaturated soils. These containment systems are meant to control high-risk contaminants that are too difficult to remove with current methods and/or pose a near-term, high risk to public health. Such systems are also implemented at sites where remediation techniques may have unintentionally mobilized contamination and threatened the water table. Since subsurface barriers are typically applied in high-risk circumstances, knowledge of their emplaced and long-term integrity is crucial. Current verification and monitoring practices (hydraulic testing, construction materials and methods QA) are limited in their ability to locate, discriminate, and resolve flaws in barrier construction. SEAtracem is a gaseous tracer verification and monitoring system developed to locate and estimate the size of flaws in subsurface barriers located above the water table. The system incorporates injection of a non-hazardous gaseous tracer in the barrier interior, multiple soil vapor sampling points located outside of the barrier, and an automated sampling and analysis system. SEAtraceTM is an autonomous, remotely accessible monitoring system intended for long duration, unattended operation. It not only collects and analyzes soil gas samples, but also applies real time data inversion to locate and size flaws in the barrier construction. The SEAtraceTM methodology was deployed at two test barrier installations sponsored by the Department of Energy Subsurface Contaminants Focus Area. The first was a small scale thinwall jet wouting barrier demonstration at the Groundwater Remediation Field Laboratory, Dover Air Force Base, and the second a large scale thickwall colloidal silica permeation grouted barrier at the Brookhaven National Laboratory. At the Dover site two test barriers and one buried known leak source were evaluated using the SEAtracem methodology. A prototype automated soil gas sampling and analysis system provided data that was analyzed on a desktop computer system. During these tests six non-engineered and one engineered flaw were detected in the barrier panels. These flaws indicated the presence of open areas in the barrier panels that allowed diffusion of tracer gas out into the soil surrounding the barriers. The buried leak source was located within 0.2m of its actual position. A fully integrated SEAtracem system was deployed to test a colloidal silica barrier at Brookhaven National Laboratory. This system incorporated 64 sampling locations, real-time data analysis, solar powered operation, and remote access via cellular phone communication. Eleven flaws were located by automated operation of the SEAtracem system. Other verification techniques such as geophysics, hydraulics, and peffluorocarbon gaseous tracers were used at both the Dover and Brookhaven test barriers. Results from these techniques were in good agreement when they could be compared. This report documents the design of the SEAtracem system, the numerical analysis that supports the evaluation of the inversion methodology, the design of the test installations, and the demonstrations at the Dover and Brookhaven sites.

Bond-counting arguments, supported by ab-initio calculations, predict a lower barrier for "leapfrog" diffusion of Pt addimers on Pt(llO)-lx2 than for adatom dif- fusion or addimer dissociation. This conflicts with experiment, possibly signaling contaminant influence.

We are pleased to submit our efforts in parallelizing the PRONTO application suite for con- sideration in the SuParCup 99 competition. PRONTO is a finite element transient dynamics simulator which includes a smoothed particle hydrodynamics (SPH) capability; it is similar in scope to the well-known DYNA, PamCrash, and ABAQUS codes. Our efforts over the last few years have produced a fully parallel version of the entire PRONTO code which (1) runs fast and scalably on thousands of processors, (2) has performed the largest finite-element transient dynamics simulations we are aware of, and (3) includes several new parallel algorithmic ideas that have solved some difficult problems associated with contact detection and SPH scalability. We motivate this work, describe the novel algorithmic advances, give performance numbers for PRONTO running on Sandia's Intel Teraflop machine, and highlight two prototypical large-scale computations we have performed with the parallel code. We have successfully parallelized a large-scale production transient dynamics code with a novel algorithmic approach that utilizes multiple decompositions for different key segments of the computations. To be able to simulate a more than ten million element model in a few tenths of second per timestep is unprecedented for solid dynamics simulations, especially when full global contact searches are required. The key reason is our new algorithmic ideas for efficiently parallelizing the contact detection stage. To our knowledge scalability of this computation had never before been demonstrated on more than 64 processors. This has enabled parallel PRONTO to become the only solid dynamics code we are aware of that can run effectively on 1000s of processors. More importantly, our parallel performance compares very favorably to the original serial PRONTO code which is optimized for vector supercomputers. On the container crush problem, a Teraflop node is as fast as a single processor of the Cray Jedi. This means that on the Teraflop machine we can now run simulations with tens of millions of elements thousands of times faster than we could on the Jedi! This is enabling transient dynamics simulations of unprecedented scale and fidelity. Not only can previous applications be run with vastly improved resolution and speed, but qualitatively new and different analyses have been made possible.

The objective of this work to develop the materials processing and design technologies required to reduce the die development time for metal mold processes from 12 months to 3 months, using die casting of Al and Mg as the example process. Sandia demonstrated that investment casting, using rapid prototype patterns produced from Stereo lithography or Selective laser Sintering, was a viable alternative/supplement to the current technology of machining form wrought stock. A demonstration die insert (ejector halt) was investment cast and subsequently tested in the die casting environment. The stationary half of the die insert was machined from wrought material to benchmark the cast half. The two inserts were run in a die casting machine for 3,100 shots of aluminum and at the end of the run no visible difference could be detected between the cast and machined inserts. Inspection concluded that the cast insert performed identically to the machined insert. Both inserts had no indications of heat checking or degradation.

This document highlights the DISCOM's Distance computing and communication team activities at the 1998 Supercomputing conference in Orlando, Florida. This conference is sponsored by the IEEE and ACM. Sandia National Laboratories, Lawrence Livermore National Laboratory, and Los Alamos National Laboratory have participated in this conference for ten years. For the last three years, the three laboratories have a joint booth at the conference under the DOE's ASCI, Accelerated Strategic Computing Initiatives. The DISCOM communication team uses the forum to demonstrate and focus communications and networking developments. At SC '98, DISCOM demonstrated the capabilities of Dense Wave Division Multiplexing. We exhibited an OC48 ATM encryptor. We also coordinated the other networking activities within the booth. This paper documents those accomplishments, discusses the details of their implementation, and describes how these demonstrations support overall strategies in ATM networking.

A Fourier Transform hyperspectral imager uses optical intereferometry to obtain hyperspectral data. Taking a Fourier Transform of the interferogram yields the frequency spectrum of the incident light. An optical system using a standard frame rate camera can generate such interferograms at a rate of 30 frames per second. Rather than store all of the raw interferogram data and process it afterwards, it is useful to have the ability to process the raw data in real time, generating and storing the hyperspectral data itself rather than the original interferograms. This real-time processing would result in a significant reduction in the data bandwidth and storage requirements, which are of particular interest in typical airborne environments with limited computing resources on board. This report details the digital signal processing algorithm and code developed for a processing subsystem based on the Texas Instruments TMS320C6201 fixed point processor. The function of this subsystem is to compute the magnitude Fourier Transform of the interferogram data at a rate of 30 frames per second.

This report describes the results of a six-year, $6.3 million project to reduce operation and maintenance (O&M) costs at power plants employing concentrating solar power (CSP) technology. Sandia National Laboratories teamed with KJC Operating Company to implement the O&M Improvement Program. O&M technologies developed during the course of the program were demonstrated at the 150-MW Kramer Junction solar power park located in Boron, California. Improvements were made in the following areas: (a) efficiency of solar energy collection, (b) O&M information management, (c) reliability of solar field flow loop hardware, (d) plant operating strategy, and (e) cost reduction associated with environmental issues. A 37% reduction in annual O&M costs was achieved. Based on the lessons learned, an optimum solar- field O&M plan for future CSP plants is presented. Parabolic trough solar technology is employed at Kramer Junction. However, many of the O&M improvements described in the report are also applicable to CSP plants based on solar power tower or dish/engine concepts.

This report describes the results of a study that investigated the synergy between electrochemical capacitors (ECs) and flywheels, in combination with each other and with batteries, as energy storage subsystems in photovoltaic (PV) systems. EC and flywheel technologies are described and the potential advantages and disadvantages of each in PV energy storage subsystems are discussed. Seven applications for PV energy storage subsystems are described along with the potential market for each of these applications. A spreadsheet model, which used the net present value method, was used to analyze and compare the costs over time of various system configurations based on flywheel models. It appears that a synergistic relationship exists between ECS and flywheels. Further investigation is recommended to quantify the performance and economic tradeoffs of this synergy and its effect on overall system costs.

The Environmental Measurement-While-Drilling (EMWD) system and Horizontal Directional Drilling (HDD) were successfully demonstrated at the Mock Tank Leak Simulation Site and the Drilling Technology Test Site, Hanford, Washington. The use of directional drilling offers an alternative to vertical drilling site characterization. Directional drilling can develop a borehole under a structure, such as a waste tank, from an angled entry and leveling off to horizontal at the desired depth. The EMWD system represents an innovative blend of new and existing technology that provides the capability of producing real-time environmental and drill bit data during drilling operations. The technology demonstration consisted of the development of one borehole under a mock waste tank at a depth of {approximately} {minus}8 m ({minus}27 ft.), following a predetermined drill path, tracking the drill path to within a radius of {approximately}1.5 m (5 ft.), and monitoring for zones of radiological activity using the EMWD system. The purpose of the second borehole was to demonstrate the capability of drilling to a depth of {approximately} {minus}21 m ({minus}70 ft.), the depth needed to obtain access under the Hanford waste tanks, and continue drilling horizontally. This report presents information on the HDD and EMWD technologies, demonstration design, results of the demonstrations, and lessons learned.

The elevation change data measured at the Big Hill SPR site over the last 10 years has been studied and a model utilized to project elevation changes into the future. The subsidence rate at Big Hill is low in comparison with other Strategic Petroleum Reserve sites and has decreased with time due to the maintenance of higher operating pressures and the normal decrease in creep closure rate of caverns with time. However, the subsidence at the site is projected to continue. A model was developed to project subsidence values 20 years into the future; no subsidence related issues are apparent from these projections.

During July-September, 1998, a jointly funded drilling operation deepened the Long Valley Exploratory Well from 7178 feet to 9832 feet. This was the third major drilling phase of a project that began in 1989, but had sporadic progress because of discontinuities in tiding. Support for Phase III came from the California Energy Commission (CEC), the International Continental Drilling Program (ICDP), the US Geological Survey (USGS), and DOE. Each of these agencies had a somewhat different agenda: the CEC wants to evaluate the energy potential (specifically energy extraction from magma) of Long Valley Caldera; the ICDP is studying the evolution and other characteristics of young, silicic calderas; the USGS will use this hole as an observatory in their Volcano Hazards program; and the DOE, through Sandia, has an opportunity to test new geothermal tools and techniques in a realistic field environment. This report gives a description of the equipment used in drilling and testing; a narrative of the drilling operations; compiled daily drilling reports; cost information on the project; and a brief summary of engineering results related to equipment performance and energy potential. Detailed description of the scientific results will appear in publications by the USGS and other researchers.

This report includes the details of the model building procedure and prediction of seismic field data. Principal Components Regression, a multivariate analysis technique, was used to model seismic data collected as two pieces of equipment were cycled on and off. Models built that included only the two pieces of equipment of interest had trouble predicting data containing signals not included in the model. Evidence for poor predictions came from the prediction curves as well as spectral F-ratio plots. Once the extraneous signals were included in the model, predictions improved dramatically. While Principal Components Regression performed well for the present data sets, the present data analysis suggests further work will be needed to develop more robust modeling methods as the data become more complex.

Modern wind turbines are fatigue critical machines that are typically used to produce electrical power from the wind. Operational experiences with these large rotating machines indicated that their components (primarily blades and blade joints) were failing at unexpectedly high rates, which led the wind turbine community to develop fatigue analysis capabilities for wind turbines. Our ability to analyze the fatigue behavior of wind turbine components has matured to the point that the prediction of service lifetime is becoming an essential part of the design process. In this review paper, I summarize the technology and describe the ''best practices'' for the fatigue analysis of a wind turbine component. The paper focuses on U.S. technology, but cites European references that provide important insights into the fatigue analysis of wind turbines.

Studies have indicated that an adaptive wind turbine blade design can significantly enhance the performance of the wind turbine blade on energy capture and load mitigation. In order to realize the potential benefits of aeroelastic tailoring, a bend-twist D-spar, which is the backbone of a blade, was designed and fabricated to achieve the objectives of having maximum bend-twist coupling and fulfilling desirable structural properties (031 & GJ). Two bend-twist D-spars, a hybrid of glass and carbon fibers and an all-carbon D-spar, were fabricated using a bladder process. One of the D-spars, the hybrid D-spar, was subjected to a cantilever static test and modal testing. Various parameters such as materials, laminate schedule, thickness and internal rib were examined in designing a bend-twist D-spar. The fabrication tooling, the lay-up process and the joint design for two symmetric clamshells are described in this report. Finally, comparisons between the experimental test results and numerical results are presented. The comparisons indicate that the numerical analysis (static and modal analysis) agrees well with test results.

This report describes the characteristics of photovoltaic arrays that maybe suitable for use with nanosatellite electronic systems. It includes a thorough literature search on power management and distribution systems for satellites as small as microsatellites. The major conclusion to be drawn is that it is the total system, including satellite electronic system, photovoltaic systems, peak power tracker and the power management and distribution systems which need to be optimized. An example of a peak power tracker is given, and a novel series connected boost unit is described which might allow the system voltage to be increased if enough photovoltaic panels to operate the systems in real time is impractical. Finally, it is recommended that the development effort be oriented and expanded to include a peak power tracker and other power management and distribution systems.

In April they received a DOE Defense Programs award for significant contributions to the Nuclear Weapons Program in developing and applying z-pinch x-ray sources to stockpile stewardship. DOE also recognized pulsed power for outstanding performance at a world-class level as part of the FY98 performance appraisal review. There were 13 Z shots: 3 for LANL weapon physics, 2 to prepare to measure the D{sub 2} equation of state (EOS), 4 to assess energetics of single-sided drive with the z-pinch-driven hohlraum, and 4 to study the variation in x-ray power with the mass of a copper converter foil inside a nested wire array for the dynamic hohlraum.

Where there is a significant actuarial basis for decision making (e.g., the occurrence of fires in single-family dwellings), there is little incentive for formal risk management. Formal risk assessments are most useful in those cases where the value of the structure is high, many people may be affected, the societal perception of risk is high, consequences of a mishap would be severe, and the actuarial uncertainty is large. For these cases, there is little opportunity to obtain the necessary experiential data to make informed decisions, and the consequences in terms of money, lives, and societal confidence are severe enough to warrant a formal risk assessment. Other important factors include the symbolic value of the structure and vulnerability to single point failures. It is unlikely that formal risk management and assessment practices will or should replace the proven institutions of building codes and engineering practices. Nevertheless, formal risk assessment can provide valuable insights into the hazards threatening high-value and high-risk (perceived or actual) buildings and structures, which can in turn be translated into improved public health, safety, and security. The key is to choose and apply the right assessment tool to match the structure in question. Design-for-reliability concepts can be applied to buildings, bridges, transportation sys- tems, dams, and other structures. The use of these concepts could have the dual benefits of lowering life-cycle costs by reducing the necessity for maintenance and repair and of enhancing the saiiety and security of the structure's users.

How to ensure the appropriate performance of our built environment in the face of normal conditions, natural hazards, and malevolent threats is an issue of emerging national and international importance. As the world population increases, new construction must be increasingly cost effective and at the same time increasingly secure, safe, and durable. As the existing infrastructure ages, materials and techniques for retrofitting must be developed in parallel with improvements in design, engineering, and building codes for new construction. Both new and renovated structures are more often being subjected to the scrutiny of risk analysis. An international conference, "Assuring the Performance of Buildings and Infrastructures," was held in May 1997 to address some of these issues. The conference was co-sponsored by the Architectural Engineering Division of the American Society of Civil Engineers (ASCE), the American Institute of Architects, and Sandia National Laboratories and convened in Albuquerque, NM. Many of the papers presented at the conference are found within this issue of Techno20~. This paper presents some of the major conference themes and summarizes discussions not found in the other papers.

In rough agreement with experimental values derived from Cu island shapes vs. temperature, ab-initio calculations yield formation energies of 0.27 and 0.26 eV/ step-edge-atom for (100)- and (111)-micro facet steps on Cu(lll), and 0.09 and 0.12 eV per kink in those steps. Comparison to ab-initio results for Al and Pt shows that as a rule, the average formation energy of straight steps on a close-packed metal surface equals -7% of the metal's cohesive energy.

The carrier lifetime in vertical cavity surface emitting lasers is determined for various oxide aperture sizes using turn-on delay measurements. The lifetime is relatively constant for large devices, but decreases for aperture sizes below 9 x 9 µm.

Chemical sensing with a magnetically excited flexural plate wave (mag- FPW) resonator has been demonstrated for the first time. One surface of the resonator was coated with ethyl cellulose to impart sensitivity to volatile solvents such as chloroform, tetrachloroethylene, trichloroethylene, and toluene. The absorbed mass of the analyte causes a shift in the membrane resonance frequency of the two-port mag-FPW resonator. An oscillator circuit is used to track the resonance frequency, providing a convenient means of monitoring analyte concentration levels. Analyte concentrations of 10 ppm were easily detected.

Coulomb driven, magneto-optically induced electron and hole bound states from a series of heavily doped GaAs/Al_0.3Ga_0.7As single heterojunctions (SHJ) are revealed in high magnetic fields. At low magnetic fields ({nu} >2), the photohuninescence spectra display Shubnikov de-Haas type oscillations associated with the empty second subband transition. In the regime of the Landau filling factor {nu} <1 and 1< {nu} <2, we found strong bound states due to Mott type Vocalizations. Since a SHJ has an open valence band structure, these bound states area unique property of the dynamic movement of the valence holes in strong magnetic fields.

The magnetophotoluminescence (MPL) behavior of a GaAs/Al_0.3Ga_0.7As single heterojunction has been investigated to 60T. We observed negatively charged singlet and triplet exciton states that are formed at high magnetic fields beyond the {nu}=l quantum Hall state. The variation of the charged exciton binding energies are in good agreement with theoretical predictions. The MPL transition intensities for these states showed intensity variations (maxima and minima) at the {nu}=l/3 and 1/5 fractional quantum Hall (FQH) state as a consequence of a large reduction of electron-hole screening at these filling factors.

The transport properties of a quasi-three-dimensional, 200 layer quantum well structure are investigated at integer filling in the quantum Hall state. We find that the transverse magnetoresistance R_xx, the Hall resistance R_xy, and the vertical resistance R_zz all follow a similar behavior with both temperature and in-plane magnetic field. A general feature of the influence of increasing in-plane field B_in is that the Hall conductance quantization first improves, but above a characteristic value B^C_in, the quantization is systematically removed. We consider the interplay of the chid edge state transport and the bulk (quantum Hall) transport properties. This mechanism may arise from the competition of the cyclotron energy with the superlattice band structure energies. A comparison of the resuIts with existing theories of the chiral edge state transport with in-plane field is also discussed.

We present here the results of polarized magneto-photoluminescence measurements on a high mobility single-heterojunction. The presence of a doublet structure over a large magnetic field range (2>v>l/6) is interpreted as possible evidence for the existence of a magneto-roton minima of the charged density waves. This is understood as an indication of strong electronic correlation even in the case of the IQHE limit.

Magnetic semiconductors offer a unique possibility for strongly tuning the intrinsic alloy disorder potential with applied magnetic field. We report the direct observation of a series of step-like reductions in the magnetic alloy disorder potential in single ZnSe/Zn(Cd,Mn)Se quantum wells between O and 60 Tesla. This disorder, measured through the linewidth of low temperature photoluminescence spectra drops abruptly at -19, 36, and 53 Tesla, in concert with observed magnetization steps. Conventional models of alloy disorder (developed for nonmagnetic semiconductors) reproduce the general shape of the data, but markedly underestimate the size of the linewidth reduction.

Single-level parallel optimization approaches, those in which either the simulation code executes in parallel or the optimiza- tion algorithm invokes multiple simultaneous single-processor analyses, have been investigated previously and been shown to be effective in reducing the time required to compute optimal solutions. However, these approaches have clear performance limita- tions that prevent effective scaling with the thousands of processors available in massively parallel supercomputers. In more recent work, a capability has been developed for multilevel parallelism in which multiple instances of multiprocessor simulations are coordinated simultaneously. This implementation employs a master-slave approach using the Message Passing Interface (MPI) within the DAKOTA software toolkit. Mathematical analysis on achieving peak efficiency in multilevel parallelism has shown that the most effective processor partitioning scheme is the one that limits the size of multiprocessor simulations in favor of concurrent execution of multiple simulations. That is, if both coarse-grained and fine-grained parallelism can be exploited, then preference should be given to the coarse-grained parallelism. This analysis was verified in multilevel paralIel computatiorud experiments on networks of workstations (NOWS) and on the Intel TeraFLOPS massively parallel supercomputer. In current work, methods for exploiting additional coarse-grained parallelism in optimization are being investigated so that fine-grained efficiency losses can be further minimized. These activities are focusing on both algorithmic coarse-grained parallel- ism (multiple independent function evaluations) through the development of speculative gradient methods and concurrent iterator strategies and on function evaluation coarse-grained parallelism (multiple separable simulations within a function evaluation) through the development of general partitioning and nested synchronization facilities. The net result is a total of four separate lev- els of parallelism which can minimize efficiency losses and achieve near linear scaling on massively parallel computers.

We have designed and tested a prototype dish/Stirling hybrid-receiver combustion system. The system consists of a pre-mixed natural-gas burner heating a pin-finned sodium heat pipe. The design emphasizes simplicity, low cost, and ruggedness. Our test was on a 1/6^th -scale device, with a nominal firing rate of 18kWt, a power throughput of 13kWt, and a sodium vapor temperature of 750°C. The air/fuel mixture was electrically preheated to 640°C to simulate recuperation. The test rig was instrumented for temperatures, pressures, flow rates, overall leak rate, and exhaust emissions. The data verify our burner and heat-transfer models. Performance and post-test examinations validate our choice of materials and fabrication methods. Based on the 1/6^th -scale results, we are designing a till-scale hybrid receiver. This is a fully-integrated system, including burner, pin-fin primary heat exchanger, recuperator (in place of the electrical pre-heater used in the prototype system), solar absorber, and sodium heat pipe. The major challenges of the design are to avoid pre-ignition, achieve robust heat-pipe performance, and attain long life of the burner matrix, recuperator, and flue-gas seals. We have used computational fluid dynamics extensively in designing to avoid pre-ignition and for designing the heat-pipe wick, and we have used individual component tests and results of the 1/6^th -scale test to optimize for long life. In this paper, we present our design philosophy and basic details of our design. We describe the sub-scale test rig and compare test results with predictions. Finally, we outline the evolution of our full-scale design, and present its current status.

Successful techniques have been developed for simulating some experimental shipboard fires. The experimental fues were staged in Holds 4 and 5 of the Mayo Lykes, a test ship operated by the United States Coast Guard Fire and Safiety Test Detachment at Little Sand Island in Mobile Bay, Alabama. The tests simulated an engine-room or galley fire in the compartment adjacent to simulated hazardous cargo. The purpose of these tests was to determine the effect the fires in Hold 4 had on the cargo in Holds 4 and 5. The simulation is done with CFX, a commercial computational fluid dynamics code. Analyses show that simulations can accurately estimate a maritime fire environment for radioactive materials packaging. Radiative heat transfer dominates the hold-fue environment near the hot bulkhead. Flame temperatures between 800 and 1000°C give heat fluxes and temperatures typical of the measured fire environment for the simulated radioactive materials package. The simulation predicted the occurrence of flow patterns near the calorimeter (simulated radioactive materials package) similar to those observed during the experiment. The simulation was also accurate in predicting a heated fluid layer near the ceiling that increases in thickness as time passes.

We have constructed a humidity-controlled chamber in which deflections of polysilicon cantilever beams are observed by interferometry, resulting in in-situ adhesion measurements within a fracture mechanics framework. From adhesion energy measurements for uncoated hydrophilic beams, we demonstrate an exponential dependence of adhesion on relative humidity (RH). We can explain this trend with a single-asperity model for capillary condensation. For coated hydrophobic beams, adhesion is independent of RH up to a threshold value which depends on the coating used. However, we have found that exposure to very high RH ({ge}90%) ambients can cause a dramatic increase in adhesion, surprisingly with a stronger effect for perfluorodecyltrichlorosilane (FDTS, C{sub 10}H{sub 4}F{sub 17}SiCl{sub 3}) than octadecyltrichlorosilane (ODTS, C{sub 18}H{sub 37}SiCl{sub 3}). Newly developed computational mechanics to measure adhesion in the presence of an applied load allow us to explore how the adhesion increase develops. We believe that water adsorption at silanol sites at the FDTS/substrate interface, possibly exacerbated by coupling agent migration, leads to water islanding and the subsequent adhesion increase at very high RH levels.

We report the first experimental observation of non-classical morphological equilibration of a corrugated crystalline surface. Periodic rippled structures with wavelengths of 290-550 nm were made on Si(OO1) by sputter rippling and then annealed at 650 - 750 °C. In contrast to the classical exponential decay with time, the ripple amplitude, A_{lambda}(t), followed an inverse linear decay, A_{lambda}(t)= A_{lambda}(0)/(1 +k_{lambda}t), agreeing with a prediction of Ozdemir and Zangwill. We measure the activation energy for surface relaxation to be 1.6±0.2 eV, consistent with an interpretation that dimers mediate transport.

Shear bands and faults are ubiquitous features of brittle rock deformation at a variety of length scales. Despite the prevalence of these features, understandhg of their inception remains rudimentary. Laboratory experiments suggest a casual association of localization of deformation (faulting) with peak stress, but more detailed examination reveals that localization can precede or follow the peak. Rudnicki and Rice (1975, hereafter abbreviated as RR) have suggested a the- ory of the inception of localization as a bifurcation or nonuniqueness of the so- lution for homogeneous deformation. They predict a strong dependence of local- ization on deformation state. In particular, they predict that localization can occur prepeak for deformation states near deviatoric pure shear and does not occur until well after peak for axisymmetric compression. This prediction is roughly in ac- cord with the true triaxial experiments of Mogi (1967, 1971). More recently, Ord et al. (1991) and Wwersik et al. (1991) have reported observations of localization prior to peak stress in plane strain experiments. The predictions of RR depend strongly on the constitutive properties of the rock and detailed comparison has been impeded by inadequate knowledge of those properties. Even the idealized constitutive model used by RR requires knowledge of the evolution of the constitutive properties with inelastic deformation that is not readily obtainable from the typical axisymmetric compression test. Although it is conceptually advantageous to consider inelastic deformation at fixed mean stress, the mean stress changes throughout the axisymmetric compression test. In this paper, we present a synthesis of a number of axisymmetric compres- sion tests to extract a detailed implementation of the constitutive framework used by RR. The resulting constitutive relation is then used to -predict the response for plane strain. Conditions for localization of deformation derived by RR are evalu- ated for both plane strain and axisymmetric compression.

Structured conversation diagrams, or conversation specifications, allow agents to have predictable interactions and achieve predefined information-based goals, but they lack the flexibility needed to function robustly in an unpredictable environment. We propose a mechanism that combines a typical conversation structure with a separately established policy to generate an actual conversation. The word "policy" connotes a high-level direction external to a specific planned interaction with the environment. Policies, which describe acceptable procedures and influence decisions, can be applied to broad sets of activity. Based on their observation of issues related to a policy, agents may dynamically adjust their communication patterns. The policy object describes limitations, constraints, and requirements that may affect the conversation in certain circumstances. Using this new mechanism of interaction simplifies the description of individual conversations and allows domain-specific issues to be brought to bear more easily during agent communication. By following the behavior of the conversation specification when possible and deferring to the policy to derive behavior in exceptional circumstances, an agent is able to function predictably under normal situations and still act rationally in abnormal situations. Different conversation policies applied to a given conversation specification can change the nature of the interaction without changing the specification.

The Instrumentation and Telemetry Departments at Sandia National Laboratories have been exploring the instrumentation of sealed canisters where the flight application will not tolerate either the presence of a chemical power source or penetration by power supply wires. This paper will describe the application of a low power micro-controller based instrumentation system that uses magnetic coupling for both power and data to support a flight application.

Junction field effect transistors (JFET) are fabricated on a GaN epitaxial structure grown by metal organic chemical vapor deposition (MOCVD). The DC and microwave characteristics of the device are presented. A junction breakdown voltage of 56 V is obtained corresponding to the theoretical limit of the breakdown field in GaN for the doping levels used. A maximum extrinsic transconductance (g_m) of 48 mS/mm and a maximum source-drain current of 270 mA/mm are achieved on a 0.8 µ m gate JFET device at V_GS= 1 V and V_DS=15 V. The intrinsic transconductance, calculated from the measured g_m and the source series resistance, is 81 mS/mm. The f_T and f_max for these devices are 6 GHz and 12 GHz, respectively. These JFETs exhibit a significant current reduction after a high drain bias is applied, which is attributed to a partially depleted channel caused by trapped hot-electrons in the semi-insulating GaN buffer layer. A theoretical model describing the current collapse is described, and an estimate for the length of the trapped electron region is given.

Ferrochelatase (EC 4.99.1.1), the terminal enzyme of the heme biosynthetic pathway, catalyzes Fe²⁺ chelation into protoporphyrin IX. Resonance Raman and W-visible absorbance spectroscopes of wild type and engineered variants of murine ferrochelatase were used to examine the proposed structural mechanism for iron insertion into protoporphyrin by ferrochelatase. The recombinant variants (i.e., H207N and E287Q) are enzymes in which the conserved amino acids histidine-207 and glutamate-287 of murine ferrochelatase were substituted with asparagine and glutamine, respectively. Both of these residues are at the active site of the enzyme as deduced from the Bacillus subtilis ferrochelatase three-dimensional structure. Addition of free base or metalated porphyrins to wild type ferrochelatase and H207N variant yields a quasi 1:1 complex, possibly a monomeric protein-bound species. In contrast, the addition of porphyrin (either free base or metalated) to E287Q is sub-stoichiometric, as this variant retains bound porphyrin in the active site during isolation and purification. The specificity of porphyrin binding is confirmed by the narrowing of the structure-sensitive resonance Raman lines and the vinyl vibrational mode. Resonance Raman spectra of free base and metalated porphyrins bound to the wild type ferrochelatase indicate a nonplanar distortion of the porphyrin macrocycle, although the magnitude of the distortion cannot be determined without first defining the specific type of deformation. Significantly, the extent of the nonplanar distortion varies in the case of H207N- and E287Q-bound porphyrins. In fact, resonance Raman spectral decomposition indicates a homogeneous ruffled distortion for the nickel protoporphyrin bound to the wild type ferrochelatase, whereas both a planar and ruffled conformations are present for the H207N-bound porphyrin. Perhaps more revealing is the unusual resonance , 3 Raman spectrum of the endogenous E287Q-bound porphyrin, which has the structure-sensitive lines greatly upshifted relative to those of the free base protoporphyrin in solution. This could be interpreted as an equilibrium between protein conformers, one of which favors a highly distorted porphyrin macrocycle. Taken together these findings suggest that the mode of porphyrin distortion in murine ferrochelatase is different from that reported for yeast ferrochelatase, which requires metal binding for porphyrin distortion.

The first synthesis of an octahalotetraalkylporphyrin [2,3,7,8,12,13,17,18 -octabromo-5,10,15,20- tetrakis(trifluoromethyl)porphinato nickel(II)] is reported; this perhalogenated porphyrin has several novel properties including a very nonplanar ruffled structure with an unusually short Ni- N distance, an extremely red-shifted optical spectrum, and hindered rotation of the trifluoromethyl groups ({Delta}G_278K =47 kJ mol^-1).

Under existing methods of probabilistic risk assessment (PRA), the analysis of fire-induced circuit faults has typically been conducted on a simplistic basis. In particular, those hot-short methodologies that have been applied remain controversial in regards to the scope of the assessments, the underlying methods, and the assumptions employed. To address weaknesses in fire PRA methodologies, the USNRC has initiated a fire risk analysis research program that includes a task for improving the tools for performing circuit analysis. The objective of this task is to obtain a better understanding of the mechanisms linking fire-induced cable damage to potentially risk-significant failure modes of power, control, and instrumentation cables. This paper discusses the current status of the circuit analysis task.

Sandia National Laboratories has undertaken an ambitious, multiyear effort to greatly improve our parachute system modeling and analysis capabilities. The impetus for this effort is twofold. First, extending the stockpile lifetime raises serious questions regarding the ability of the parachutes to meet their requirements in the future due to material aging. These aging questions cannot currently be answered using available tools and techniques which are based upon the experience of expert staff and full-scale flight tests and are, therefore, not predictive. Second, the atrophy of our parachute technology base and the loss of our experienced staff has eroded our ability to respond to any future problems with stockpiled parachutes or to rapidly design a new parachute system on an experience base alone. To assure a future in-house capability for technical oversight of stockpile nuclear weapon parachutes, Sandia must move from our present empirically based approach to a computationally based, predictive methodology. This paper discusses the current status of the code development and experimental validation activities. Significant milestones that have been achieved and those that are coming up in the next year are discussed.

The sensitivity and selectivity of polyvinyl alcohol (PVA) / carbon black composite films have been found to vary depending upon the hydroxylation percentage ("-OH") of the polymer. These chemiresistors made from PVA films whose polymer backbone is 88% hydroxylated (PVA88) have a high sensitivity to water, while chemiresistors made from PVA75 have a higher sensitivity to methanol. The minor differences in polymer composition result in films with different Hildebrand volubility parameters. The relative responses of several different PVA-based chemiresistors to solvents with different volubility parameters are presented. In addition, polyvinyl acetate (PVAC) films with PVA88 are used in an array to distinguish the responses to methanol-water mixtures.

A better understanding of the fraction of contaminants irreversibly sorbed by minerals is necessary to effectively quantify bioavailability. Ferrihydrite, a poorly crystalline iron oxide, is a natural sink for sorbed contaminants. Contaminants may be sorbed/occluded as ferrihydrite precipitates in natural waters or as it ages and transforms to more crystalline iron oxides such as goethite or hematite. Laboratory studies indicate that Cd, Co, Cr, Cu, Ni, Np, Pb, Sr, U, and Zn are irreversibly sorbed to some extent during the aging and transformation of synthetic ferrihydrite. Barium, Ra and Sr are known to sorb on ferrihydrite in the pH range of 6 to 10 and sorb more strongly at pH values above its zero point of charge (pH> 8). We will review recent literature on metal retardation, including our laboratory and modeling investigation of Ba (as an analogue for Ra) and Sr adsorption/resorption, during ferrihydrite transformation to more crystalline iron oxides. Four ferrihydrite suspensions were aged at pH 12 and 50 °C with or without Ba in 0.01 M KN03 for 68 h or in 0.17 M KN03 for 3424 h. Two ferrihydrite suspensions were aged with and without Sr at pH 8 in 0.1 M KN03 at 70°C. Barium or Sr sorption, or resorption, was measured by periodically centrifuging suspension subsamples, filtering, and analyzing the filtrate for Ba or Sr. Solid subsamples were extracted with 0.2 M ammonium oxalate (pH 3 in the dark) and with 6 M HCl to determine the Fe and Ba or Sr attributed to ferrihydrite (or adsorbed on the goethite/hematite stiace) and the total Fe and Ba or Sr content, respectively. Barium or Sr occluded in goethite/hematite was determined by the difference between the total Ba or Sr and the oxalate extractable Ba or Sr. The percent transformation of ferrihydrite to goethite/hematite was estimated from the ratio of oxalate and HC1 extractable Fe. All Ba was retained in the precipitates for at least 20 h. Resorption of Ba reached a maximum of 7 to 8% of the Ba2+ added for samples aged in 0.01 and 0.17 M KN03 after 68 and 90 h of aging, respectively. About 3% of the Ba2+ added was readsorbed from 90 to 3424 h of aging in 0.17 M KN03. The amount of Ba sorbed by ferrihydrite or adsorbed on goethite (oxalate-extractable) decreased from 70 to 40% of the Ba2+ added after 68 h in 0.01 M KNO3 and from 80 to 20% of the Ba2+ added after 400 h in 0.17 M KN03. The Ba occluded in goethite (HCl-extractable) in 0.01 M KN03 increased rapidly to 30% of the Ba2+ added in the first 0.4 h and then to 50% of the Ba2+ added after 68 h. In 0.17 M KN03, Ba occluded in goethite increased from 60% of the Ba2+ added by 68 h and to 75% of the Ba2+ added after 3424 h. After 68 h at 70°C, ferrihydrite transformation was 99% compIete and was slightly inhibited with Sr present during the first few hours. Occlusion of Sr in ferrihydrite or Sr reversibly adsorbed decreased from 96 to 4o/0 after 86 h. Occlusion of Sr in hematite/goethite increased from 4 to 40% after 68 h. Resorption of Sr increased from 0.2 to 50% after 68 h. At least 90% of the Ba and 25% of the Sr added to the ferrihydrite suspensions were retained by the iron oxides during the aging periods in this study. At least 75% of the Ba and 15% of the Sr were irreversibly sorbed during ferrihydrite transfomnation to goethite and/or hematite.

Microstructural-level residual stresses arise in ceramics due to thermal expansion anisotropy. The magnitude of these stresses can be very high and may cause spontaneous microcracking during the processing of these materials. The orientation data obtained by backscattered electron diffraction and grain boundary energies obtained by AFM were used in conjunction with an object oriented finite element analysis package (OOF) to predict the magnitude of residual stresses in alumina. Crack initiation and propagation were also simulated based on the Griffith fracture criterion.

Incomplete convergence in numerical simulation such as computational physics simulations and/or Monte Carlo simulations can enter into the calculation of the objective function in an optimization problem, producing noise, bias, and topo- graphical inaccuracy in the objective function. These affect accuracy and convergence rate in the optimization problem. This paper is concerned with global searching of a diverse parameter space, graduating to accelerated local convergence to a (hopefully) global optimum, in a framework that acknowledges convergence uncertainty and manages model resolu- tion to efficiently reduce uncertainty in the final optimum. In its own right, the global-to-local optimization engine employed here (devised for noise tolerance) performs better than other classical and contemporary optimization approaches tried individually and in combination on the "industrial" test problem to be presented.

This is a period of ever-tightening defense budgets and continuing pressure on the public sector to be more commercial-like, Property policies, practices, and regulations are increasingly being challenged and changed. In these times, we must be leaders in understanding and defining the value of our profession from a commercial standpoint so that we can provide the right services to our customers and explain and defend the value of those services. To do so, we must step outside current property management practices, regulations, and oversight. We must learn to think and speak in the language of those who fund us--a financial language of risk, cost, and benefit. Regardless of regulation and oversight, our bosses are demanding that we demonstrate (financially) the benefits of current practice, or else. This article is intended to be the beginning of an effort to understand and define our profession in terms of risk, cost, and benefit so that we can meet these new challenges. The first step in this effort must be defining and measuring risk, cost, and benefit. Our costs, although sometimes difficult to capture, are easy to understand: they are almost exclusively the effort, both within and without the property management organization, involved in managing property. Unfortunately, property risks and benefits are not so simple or so well understood. Generally, risks and benefits are identified and measured through physical inventory results: potential and actual shortages. This paper will explore the weaknesses in the current understanding and use of shortage information as the yardstick for property management risks and performance. It will define a new framework for understanding the purpose and value of property management. And finally, it will set a course for a new method of measuring and valuing physical inventoty shortages. This new method will yield accurate and useful measures of property management risk and benefit. Once risk and benefit are accurately understood and measured, it will be possible to evaluate, adjust, and explain property management practices and regulations from a commercial, financial perspective; it will be possible for us to be the leaders in redefining the purpose and value of the property management profession for today's environment.

Interest in the critical dynamics of superfluid ⁴ He in microgravity conditions has motivated the development of new high resolution thermometry technol- ogy for use in space experiments near 2K. The current material commonly used as the temperature sensing element for high resolution thermometers (HRTs) is copper ammonium bromide [Cu(NH₄)₂Br₄2H₂0) or "CAB", which undergoes a ferromagnetic phase transition at 1.8K1. HRTs made from CAB have demonstrated low drift (< 10fK/s) and a temperature resolu- tion of O.lnK. Unfortunately, paramagnetic salts such as CAB are difficult to prepare and handle, corrosive to most metals, and become dehydrated if kept, under vacuum conditions at room temperature. We have developed a magnetic thermometer using dilute magnetic alloys of Mn or Fe dissolved in a pure Pd matrix. These metallic thermometers are easy to fabricate, chemically inert, and mechanically robust. Unlike salts, they may be directly soldered to the stage to be measured. Also, the Curie temperature can be varied by changing the concentration of Fe or Mn, making them available for use in a wide temperature range. Susceptibility measurements, as well as preliminary noise and drifl measurements, show them, to have sub-nK resolution, with a drift of less than 10^-13 K/s.

Abstract not provided.

Commercial telemedicine systems are increasingly functional, incorporating video-conferencing capabilities, diagnostic peripherals, medication reminders, and patient education services. However, these systems (1) rarely utilize information architectures which allow them to be easily integrated with existing health information networks and (2) do not always protect patient confidentiality with adequate security mechanisms. Using object-oriented methods and software wrappers, we illustrate the transformation of an existing stand-alone telemedicine system into `plug-and-play' components that function in a distributed medical information environment. We show, through the use of open standards and published component interfaces, that commercial telemedicine offerings which were once incompatible with electronic patient record systems can now share relevant data with clinical information repositories while at the same time hiding the proprietary implementations of the respective systems. Additionally, we illustrate how leading-edge technology can secure this distributed telemedicine environment, maintaining patient confidentiality and the integrity of the associated electronic medical data. Information surety technology also encourages the development of telemedicine systems that have both read and write access to electronic medical records containing patient-identifiable information. The win-win approach to telemedicine information system development preserves investments in legacy software and hardware while promoting security and interoperability in a distributed environment.

The Sandia ACRR (a Hazard Category 2 Nuclear Reactor Facility) was defueled in June 1997 to modify the reactor core and control system to produce medical radioisotopes for the Department of Energy (DOE) Isotope Production Program. The DOE determined that an Operational Readiness Review (ORR) was required to confirm readiness to begin operations within the revised safety basis. This paper addresses the ORR Process, lessons learned from the Sandia and DOE ORRS of the ACRR, and the use of the ORR to confirm authorization basis implementation.

The Sandia National Laboratories/New Mexico (SNL/NM) Environmental Restoration Project is halfway through excavating the Classified Waste Landfill in Technical Area II, a disposal area for weapon components for approximately 40 years. While the planning phase of any project is important, it is only a means of getting to the field implementation phase where reality quickly sinks in. Documents outlining the general processes are developed, heavy equipment, supply needs, requisite skills, and staffing levels are anticipated, and contingencies for waste management are put in place. However, the nature of landfill excavation dictates that even the most detailed plans will probably change. This project is proving that trying to account for undefined variables and predicting the total cost of landfill remediation is very difficult if the contents are not well known. In landfill excavation, contingency cannot be minimized. During development of the waste management plan, it was recognized that even the best forecasting could not formulate the perfect cradle-to-grave processes because waste streams are rarely definable before excavation begins. Typically, as excavation progresses and waste streams are generated, new characterization information allows further definition of disposal options which, in turn, modify the generation/management process. A general plan combined with close involvement of waste management personnel to resolve characterization and packaging questions during generation has worked very well. And, as expected, each new pit excavated creates new waste management challenges. The material excavated consists primarily of classified weapon assemblies and related components, so disposition must include demilitarization and sanitization. The demilitarization task at the start of the project was provided by an SNL/NM group that has since lost their funding and operational capability. This project is having to take on the task of disassembly, destruction, and recycling of classified components, along with the associated costs and infrastmcture. Very stringent radiological controls were imposed on site operations during the planning phase. Radiological controls that are not justified significantly impact the efficiency and cost of operations. If the initial approach is too conservative, there should be well-defined provisions for scaling down the protective measures to reflect the actual risks. Once the effectiveness of early detection, monitoring, and surveys is proven, radiological controls and postings should be re-evaluated to verify that they are appropriate. High levels of heavy metals dust were not anticipated during the planning phase but were suspected, then confirmed, during material handling. Respiratory protection and monitoring were upgraded accordingly and the costs added to the baseline. In contrast to radiological constraints, industrial hygiene guidelines were worked into the process with a minimum of adverse impact. While a lot of unforeseen expenses occur, some expected costs can be reduced. During the planning phase, the anticipated need to adequately characterize a variety of radionuclides in soil led to using Large Area Gamma Spectroscopy (LAGS) to survey all the soil excavated. About a quarter of the way through the project, it was obvious that very little radioactive material was present in the excavated soils. Since all the soil is processed through a screen plant, producing a fairly homogeneous mix, a more common method of sampling soil piles was implemented to replace the LAGS unit, increase productivity, and reduce costs. In summary, the most important lesson is to expect and be ready to change. Excavating a landfill requires the flexibility to quickly adjust processes to handle the unknown variables, and close attention to detail so all the different facets of the project are kept under control.

Thermally stimulated current and capacitance voltage methods are used to investigate the thermal stability of trapped electrons associated with radiation-induced trapped positive charge in metaloxide-semiconductor capacitors. The density of deeply trapped electrons in radiation-hardened 45 nm oxides exceeds that of shallow electrons by a factor of ∼3 after radiation exposure, and by up to a factor of 10 or more during biased annealing. Shallow electron traps anneal faster than deep traps, and exhibit response that is qualitatively consistent with existing models of compensated E′γ centers in SiO2. Deeper traps may be part of a different dipole complex, and/or have shifted energy levels that inhibit charge exchange with the Si. © 1999 American Institute of Physics.

Thermite mixtures, intermetallic reactants, and metal fuels have long been used in pyrotechnic applications. Advantages of these systems typically include high energy density, high combustion temperature, and a wide range of gas production. They generally exhibit high temperature stability and possess insensitive ignition properties. For the specific applications of humanitarian demining and disposal of unexploded ordnance, these pyrotechnic formulations offer additional benefits. The combination of high thermal input with low brisance can be used to neutralize the energetic materials in mines and other ordnance without the "explosive" high-blast-pressure events that can cause extensive collateral damage to personnel, facilities, and the environment. In this paper, we review the applications, benefits, and characteristics of thermite mixtures, intermetallic reactants, and metal fuels. Calculated values for reactant density, heat of reaction (per unit mass and per unit volume), and reaction temperature (without and with consideration of phase changes and the variation of specific heat values) are tabulated. These data are ranked in several ways, according to density, heat of reaction, reaction temperature, and gas production.

The effects on electrochemical performance of the nitrogen content of disordered carbons derived from polymethacryonitrile (PMAN)-divinylbenzene (DVB) copolymers were examined in galvanostatic cycling tests between 2 V and 0.01 V vs. Li/Li+ in lM LiPF₆/ethylene carbonate (EC)-dimethyl carbonate (DMC). The first-cycle reversible capacities and coulombic efficiencies increased with increase in the level of nitrogen for samples prepared at 700°C. However, the degree of fade also increased. Similar tests were performed on materials that were additionally heated at 1,000° and 1,300°C for five hours. Loss of nitrogen, oxygen, and hydrogen occurred under these conditions, with none remaining at the highest temperature in all cases but one. The pyrolysis temperature dominated the electrochemical performance for these samples, with lower reversible and irreversible capacities for the first intercalation cycle as the pyrolysis temperature was increased. Fade was reduced and coulombic efficiencies also improved with increase in temperate. The large irreversible capacities and high fade of these materials makes them unsuitable for use in Li-ion cells.

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

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

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

Abstract not provided.

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

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

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

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

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

Abstract not provided.

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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