In-situ barrier materials and designs are being developed for containment of high risk contamination as an alternative to immediate removal or remediation. The intent of these designs is to prevent the movement of contaminants in either the liquid or vapor phase by long-term containment, essentially buying time until the contaminant depletes naturally or a remediation can be implemented. The integrity of the resultant soil-binder mixture is typically assessed by a number of destructive laboratory tests (leaching, compressive strength, mechanical stability with respect to wetting and freeze-thaw cycles) which as a group are used to infer the likelihood of favorable long-term performance of the barrier. The need exists for a minimally intrusive yet quantifiable methods for assessment of a barrier`s integrity after emplacement, and monitoring of the barrier`s performance over its lifetime. Here, the authors evaluate non-destructive measurements of inert-gas diffusion (specifically, SF{sub 6}) as an indicator of waste-form integrity. The goals of this project are to show that diffusivity can be measured in core samples of soil jet-grouted with Portland cement, validate the experimental method through measurements on samples, and to calculate aqueous diffusivities from a series of diffusion measurements. This study shows that it is practical to measure SF{sub 6} diffusion rates in the laboratory on samples of grout (Portland cement and soil) typical of what might be used in a barrier. Diffusion of SF{sub 6} through grout (Portland cement and soil) is at least an order of magnitude slower than through air. The use of this tracer should be sensitive to the presence of fractures, voids, or other discontinuities in the grout/soil structure. Field-scale measurements should be practical on time-scales of a few days.
This paper describes updates and revisions to the data acquisition computer program DATAVG which has served as the basic data collection system for the Sandia National Laboratories Geomechanics Department, Rock Mechanics Laboratory since late 1992. DATAVG was first described in Event Triggered Data Acquisition in the Rock Mechanics Laboratory, [Hardy, 1993]. DATAVG has been modified to incorporate numerous user-requested enhancements and a few bug fixes. In this paper these changes to DATAVG are described.
The generation of particles in gas handling systems as a result of corrosion is a major concern in the microelectronics industry. The corrosion can be caused by the presence of trace quantities of water in corrosive gases such as HCl or HBr. FTIR spectroscopy has been shown to be a method that can be made compatible with corrosive gases and is capable of detecting low ppb levels of water vapor. In this report, the application of FTIR spectroscopy combined with classical least squares multivariate calibration to detect trace H{sub 2}O in N{sub 2}, HCl and HBr is discussed. Chapter 2 discusses the gas handling system and instrumentation required to handle corrosive gases. A method of generating a background spectrum useful to the measurements discussed in this report, as well as in other application areas such as gas phase environmental monitoring, is discussed in Chapter 3. Experimental results obtained with the first system are presented in Chapter 4. Those results made it possible to optimize the design options for the construction of a dedicate system for low ppb water vapor determination. These designs options are discussed in Chapter 5. An FTIR prototype accessory was built. In addition, a commercially available evacuable FTIR system was obtained for evaluation. Test results obtained with both systems are discussed in Chapter 6. Experiments dealing with the interaction between H{sub 2}O-HCl and potential improvements to the detection system are discussed in Chapter 7.
Dose enhancement and dose rate were measured in more than a dozen gamma sources using pMOS RADFETs and TLDs from two independent sources. ARACOR X-ray dose rates were calibrated using single- and dual-dielectric RADFETs.
The Photovoltaic Manufacturing Technology Program (PVMaT) program began in 1990 as a cost-shared partnership among the US photovoltaic industry and the US Photovoltaic Program. Balance-of-systems (BOS) components and concepts were included under Phase 4A1 of the program. BOS contracts ranged from newly developed AC PV modules to 100kW inverters for photovoltaic applications. Utility-interactive, stand-alone and hybrid components were also improved, while better manufacturing processes were developed. Specific products developed through Phase 4A1 contracts included AC modules and module integrated inverters, an advanced polymer system to reduce BOS costs, low cost integrated tracking PV systems, improved inverters, new concept inverters, communications links for BOS, and advanced modular PV systems for remote applications. This paper summarizes the research and development work, presents product and applications improvements, and describes manufacturing improvements while analyzing performance and cost benefits.
To achieve the lowest life-cycle cost (LCC), photovoltaic (PV) systems must have the optimum mix of low first cost, low operation and maintenance (O&M) cost, and high availability. Additionally, the long-term health of the photovoltaic (PV) industry requires that PV systems work as expected. Although PV modules now enjoy high reliability due to a significant multi-year effort by both the U.S. Department of Energy (DOE) and industry, the same is not always true of PV systems. Even for systems that do operate reliably, customers, suppliers, and manufacturers can benefit from knowing what O&M expenses to expect. This knowledge will reduce technology risk to the customer and improve likelihood of commitment to PV projects. System integrators and utilities may benefit from O&M cost information to improve system designs, to properly price service agreements and warranties, and to optimize maintenance strategies. The DOE and component manufacturers may benefit from identifying cost drivers to optimally focus research and quality assurance resources to improve product reliability. This paper discusses the first of five tasks identified for this project, quantifying system reliability and life cycle cost by collecting, analyzing and reporting data on PV system reliability and cost. Industry participants collect the necessary O&M data on systems they are monitoring. Sandia provides support in the form of assistance identifying data that needs to be collected, helping develop forms or databases to collect the data, and analyzing the data.
The performance of an amp-hour (Ah) counting battery charge control algorithm has been defined and tested using the Digital Solar Technologies MPR-9400 microprocessor based PV hybrid charge controller. This work included extensive field testing of the charge algorithm on flooded lead-antimony and valve regulated lead-acid (VRLA) batteries. The test results after one-year have demonstrated that PV charge utilization, battery charge control, and battery state of charge (SOC) has been significantly improved by providing maximum charge to the batteries while limiting battery overcharge to manufacturers specifications during variable solar resource and load periods.
An industry supported task group has recently completed writing proposals for changes in bring Article 690 of the 1999 National Electrical Code (NEC{reg_sign}) up to the state-of-the-art in photovoltaic device and system technology. This paper summarizes proposed code changes, discusses background on both new and changed, and presents examples for the proposed changes. Topics such as the proposed new temperature compensation table for calculating maximum system voltage are analyzed. Procedures for calculating conductor sizes with the proposed changes are presented. Impacts on photovoltaic installations, building integrated systems, and AC module installations are also analyzed.
A nonlinear discretization scheme in space and energy, based on the recently developed exponential discontinuous method, is applied to continuous slowing down dominated electron transport (i.e., in the absence of scattering.) Numerical results for dose and charge deposition are obtained and compared against results from the ONELD and ONEBFP codes, and against exact results from an adjoint Monte Carlo code. It is found that although the exponential discontinuous scheme yields strictly positive and monotonic solutions, the dose profile is considerably straggled when compared to results from the linear codes. On the other hand, the linear schemes produce negative results which, furthermore, do not damp effectively in some cases. A general conclusion is that while yielding strictly positive solutions, the exponential discontinuous method does not show the crude cell accuracy for charged particle transport as was apparent for neutral particle transport problems.
Two methods for the use of lunar materials for the construction of shelters on the Moon are being proposed: explosive consolidation of the soil into structural components and plasma spraying of the soil to join components. The plasma-sprayed coating would also provide protection from the intense radiation. In this work, a mare simulant was plasma-sprayed onto a stainless steel substrate. Deposition of a 0.020 inch coating using power inputs of 23, 25, 27 and 29 kW were compared. Hardness of the coatings increased with each increase of power to the system, while porosity at the interface decreased. All coatings exhibited good adhesion. Simultaneously, an explosively consolidated sample was similarly characterized to afford a comparison of structural features associated with each mode of proposed use.
In 1996, Sandia National Laboratories (SNL) undertook a major effort to develop, produce, and execute a Sites Comprehensive Plan. Fundamentally, this document is intended to serve as a tool to clarify the strategic link between (1) current and future mission needs and responsibilities, and (2) the condition, capacity, and required amount of facilities space and infrastructure. It documents the Facilities Group`s response to programmatic requests for capability and makes the case for the required facilities investments through integrated master plans that document SNL`s short- and long-range needs. This paper outlines the history and business environment that led to the writing of the plan, the organizations and committees involved, the steps required to develop and produce it, the challenges encountered in selling it, both internally and externally, and the issues involved in executing the proposed actions set forth in the plan. The paper also articulates the benefits gained by Facilities Management (FM) and the corporation, as well as the lessons learned in producing the plan. SNL has concluded that the Sites Comprehensive Plan was a worthwhile effort in terms of retained facilities investment funding, increased awareness of facility needs, and other measures, despite the significant effort and cost required to produce it.
This report outlines the future technology needs of the Chemical Industry in the area of catalysis and is a continuation of the process that produced the report Technology Vision 2020: The U.S. Chemical Industry and the Council for Chemical Research`s (CCR) Chemical Synthesis Team follow-up work in chemical synthesis. Vision 2020 developed a 25-year vision for the chemical industry and outlined the challenges to be addressed in order to achieve this vision. This report, which outlines the catalysis technology roadmap, is based on the output of the CCR`s Chemical Synthesis Team, plus a workshop held March -20-21, 1997, which included about 50 participants, with catalysis experts from industry, academia, and government. It is clear that all participants view catalysis as a fundamental driver to the 0274 economic and environmental viability of the chemical industry. Advances in catalytic science and technology are among the most crucial challenges to achieving the goals of the chemical industry advanced in Vision 2020.
Linear schemes applied to charged particle transport problems demonstrate high order accuracy but under certain conditions can also produce negative solutions. On the other hand, the recently developed nonlinear exponential discontinuous (ED) method has been shown to produce accurate strictly positive solutions, for positive sources, in neutral particle transport applications. We have applied this method to the solution, in space and energy, of the multispecies transport equations for relativistic heavy ions. The solution may be useful as a treatment planning tool for the irradiation of certain cancers using heavy ions. Collisions between projectile ions and atoms in the target medium can result in ion fragments different from the original species. The solution includes these projectile fragments. The primary ion and all fragments are treated using the straight ahead approximation under which the fragments continue on with the same velocity as the original projectile.
Sandia National Laboratories (SNL) has recently completed the irradiation of five isotope production targets at its Annular Core Research Reactor (ACRR) using targets fabricated by Los Alamos National Laboratory. Four of the irradiated targets were chemically processed in the SNL Hot Cell Facility (HCF) using the Cintichem process. The Cintichem method for processing {sup 99}Mo isotope production targets involves dissolution of a UO{sub 2} coating, separation of the Mo from the other fission products, and purifying the final product. Several processing issues were addressed during the initial process verification work. This paper discusses the results of work involving dissolving the UO{sub 2} coating, recovering Mo losses in purification columns, and radiation exposure testing of process glassware and components.
As part of the Isotope Production Program at Sandia National Laboratories New Mexico (SNL/NM), procedures are being finalized for the production of {sup 99}Mo from the irradiation of {sup 235}U-coated stainless steel targets at the Technical Area (TA) V reactor and hot cell facilities. Methods have been identified and tested for the management of the non-product (waste) material as the final step in the production process. These methods were developed utilizing the waste material from a series of cold and hot tests, beginning with depleted uranium powder and culminating with a test involving an irradiated {sup 235}U target with an initial fission product inventory of approximately 18,000 Ci at the end of the irradiation cycle.
The ARRAMIS risk and reliability analysis software suite developed by Sandia National Laboratories enables analysts to evaluate the safety and reliability of a wide range of complex systems whose failure results in high consequences. This software was originally designed to model the systems, responses, and phenomena associated with potential severe accidents at commercial nuclear power reactors by solving very large fault tree and event tree models. However, because of its power and versatility, ARRAMIS and its constituent analysis engines have recently been used to evaluate a wide variety of systems, including nuclear weapons, telecommunications facilities, robotic material handling systems, and aircraft systems using hybrid fault tree event tree analysis techniques incorporating fully integrated uncertainty analysis capabilities. This paper describes recent applications in the area of nuclear reactor accident progression analysis using a large event tree methodology and the ARRAMIS package.
Heavy charged particles deposit much of their kinetic energy at very high rates in small volumes near the end of their range. This characteristic, coupled with the availability of modern particle accelerators, has sparked a revival of interest in the use of ions as a possible treatment tool for certain types of cancers. Collisions between projectile ions and atoms in the target medium can result in ion fragments that are different from the original projectile species. The energy deposition characteristics of these fragments differ from those of the projectile in a manner that allows them to travel beyond the range of the original particle. This can result in deposition of doses in healthy tissue beyond the tumor. The loss of projectiles due to the fragmentation process will also affect the dose deposited in the target tumor. An accurate dose calculation requires that these effects be taken into account. Monte Carlo calculations are expensive, time consuming, and can be limited in the number of ion species considered. Linear methods can yield high-order accuracy but can sometimes exhibit the undesirable characteristic of calculating negative fluxes. In order to bypass these difficulties, we have applied the recently developed exponential discontinuous (ED) finite- element method to a calculation of dose deposition by relativistic heavy ion projectiles and fragments. The ED method has been shown to yield strictly -- positive solutions for positive sources of neutral particles.
In applications dealing with the deposition of amorphous hydrogenated carbon layers or in the determination of the composition of deposited layers on the walls of nuclear fusion plasma experiments, the analysis of mixtures of light elements on heavy substrates is necessary. Depth profiling by means of RBS is often difficult due to the overlap of the backscattering intensities of different constituents from different depths. The erosion and reaction of deposited amorphous deuterated carbon (a-C:D) films with a Be substrate due to annealing in air poses an analytical challenge especially if simultaneously the exchange of hydrogen isotopes should be monitored. The analysis of the different recoiling atoms from collisions with heavy ions in Elastic Recoil Detection (ERD) can provide a tool which resolves all constituents in a single analysis. In the present study the composition of intermixed layers on Be containing H, D, Be, C and O has been analyzed using conventional {sup 4}He RBS at 2.2 MeV together with 2.5 MeV {sup 4}He ERD for hydrogen isotope analysis. At these energies, an overlap of signals from different constituents could be avoided in most cases. As alternative method heavy ion ERD using Si{sup 7+} ions extracted from a 5 MeV Tandem Van de Graff accelerator was investigated. At a scattering angle of 30{degree} Si ions could not be scattered into the detector and a solid state detector without protecting foil could be used. Even in the intermixed layers at terminal energies of 5 MeV the heavy constituents could be separated while signals from recoiling hydrogen and deuterium atoms could be resolved on top of the signal from the Be substrate. For the analysis of the RBS and ERD data the newly developed spectra simulation program SIMNRA has been used which includes a large data bank for scattering and nuclear reaction cross sections. The depth profiles of all constituents extracted from the simulation are compared for both methods.
This paper presents ion beam induced charge collection (IBICC) contrast images showing regions of differing charge collection efficiency within optoelectronic modulator devices. The experiments were carried out at the Sandia nuclear microprobe using 18 MeV carbon and 2 MeV helium ions. Lines of varying densities are observed to run along the different {l_brace}110{r_brace} directions which correlate with misfit dislocations within the 392nm thick strained layer superlattice quantum well of the modulator structure. Independent cross-sectional TEM studies and the electrical properties of the devices under investigation suggest the presence of threading dislocations in the active device region at a density of {approximately} 10{sup 6} cm{sup {minus}2}. However, no clear evidence of threading dislocations was observed in the IBICC images as they are possibly masked by the strong contrast of the misfit dislocations. Charge carrier transport within the modulator is used to explain the observed contrast. The different signal to noise levels and rates of damage of the incident ions are assessed.
Remote sensing by satellite is increasingly important to the national government for treaty verification, battlefield monitoring, and other activities. In addition, civilian oriented applications are increasing in areas such as geology, meteorology, ecology, forestry, and agriculture. Spectral imaging sensors, an important subclass of satellite-borne sensors, have been shown to provide information far superior to that of conventional panchromatic images in many of these applications. However, spectral imaging adds at least two challenges to the already difficult task of viewing the earth from a distance of hundreds of kilometers. First, with numerous spectral channels, the signal-to-noise ratio is decreased in any one channel. Second the data rates of spectral imaging sensors (10 Mbytes/sec, or more) stress the limits of the electronic systems, including the onboard data storage, the downlink bandwidth, and the earthbound image analysis system. This report describes a new concept which the authors have dubbed the information-efficient spectral imaging sensor (ISIS) which addresses these two problems. In addition, it offers the promise of nearly real-time identification of targets.
Main-stream applications are beginning to incorporate public key cryptography. It can be difficult to deploy this technology without a robust infrastructure to support it. It can also be difficult to deploy a public key infrastructure among multiple enterprises when different applications and standards must be supported. This discussion chronicles the efforts by a team within the US Department of Energy`s Nuclear Weapons Complex to build a public key infrastructure and deploy applications that use it. The emphasis of this talk will be on the lessons learned during this effort and an assessment of the overall impact of this technology.
The sandstones of the Molina Member of the Wasatch Formation in the Piceance basin of northwestern Colorado contain a suite of fractures that have a conjugate-pair geometry. The fractures are vertical and intersect at an acute angle of between 20 and 40 degrees. Although direct evidence of shear is rare, the fracture surfaces commonly display small steps. The fracture geometries suggest that the maximum compressive stress during fracturing was in the plane of the acute angle of the conjugate fractures: the steps are interpreted as broken-face manifestations of very low angle en echelon fractures, formed within exceptionally narrow zones of incipient shear. In contrast to the highly anisotropic permeability enhancement created by subparallel vertical extension fractures in the underlying Mesaverde Formation, the conjugate pairs in the Molina sandstones should create a well connected and relatively isotropic mesh of fracture conductivity. Increases in stress magnitudes and anisotropy during production drawdown of reservoir pressures should cause shear offsets along the fractures, initially enhancing permeability.
In January, 1995 a collaborative effort to improve radiological consequence analysis methods and tools was initiated between the V.G. Khlopin Institute (KRI) and Sandia National Laboratories (SNL). The purpose of the collaborative effort was to transfer SNL`s consequence analysis methods to KRI and identify opportunities for collaborative efforts to solve mutual problems relating to the safety of radiochemical facilities. A second purpose was to improve SNL`s consequence analysis methods by incorporating the radiological accident field experience of KRI scientists (e.g. the Chernobyl and Kyshtym accidents). The initial collaborative effort focused on the identification of: safety criteria that radiochemical facilities in Russia must meet; analyses/measures required to demonstrate that safety criteria have been met; and data required to complete the analyses/measures identified to demonstrate the safety basis of a facility.
For over fifteen years Sandia National Laboratories has been involved in laboratory testing of biometric identification devices. The key concept of biometric identification devices is the ability for the system to identify some unique aspect of the individual rather than some object a person may be carrying or some password they are required to know. Tests were conducted to verify manufacturer`s performance claims, to determine strengths/weaknesses of devices, and to determine devices that meet the US Department of energy`s needs. However, during recent field installation, significantly different performance was observed than was predicted by laboratory tests. Although most people using the device believed it operated adequately, the performance observed was over an order of magnitude worse than predicted. The search for reasons behind this gap between the predicted and the actual performance has revealed many possible contributing factors. As engineers, the most valuable lesson to be learned from this experience is the value of scientists and engineers with (1) common sense, (2) knowledge of human behavior, (3) the ability to observe the real world, and (4) the capability to realize the significant differences between controlled experiments and actual installations.
The National Environmental Policy Act (NEPA) requires that federal agencies prepare environmental impact statements (EISs) on proposals for major Federal action significantly affecting the quality of the human environment. The Council on Environmental Quality (CEQ) regulations require that EISs be prepared directly by the lead agency or a contractor it selects. EIS contractors must execute a disclosure statement specifying that they have ``no financial or other interest`` in the outcome of the project. The intent of the ``conflict of interest`` prohibition is to ensure that the EIS is defensible, free of self-serving bias, and credible to the public. Those coming to the federal government for money, permits, or project approvals must not be placed in the position of analyzing the environmental consequences of their own proposals. This paper analyzes the conflict of interest problem faced by government contractors who maintain and operate government-owned or-controlled facilities for which EISs are required. In the US Department of Energy (DOE) system, these are referred to as ``M and O`` contractors. It also examines organizational conflicts presented by current or prospective government contractors who have a financial or other interest in the outcome of a project or program for which an EIS is prepared. In responding to these and related questions, the paper discusses and interprets the CEQ regulations and guidance on EIS preparation conflict of interest as well as leading federal court opinions. It also distinguishes ``preparers`` from ``participants`` in the EIS preparation process.
Discharges in gas mixtures of Cl{sub 2}, BCl{sub 3}, Ar, and N{sub 2} are used by the integrated circuit industry for metal etching, and are as yet not well understood, especially in inductively-coupled plasma (ICP) sources which are rapidly becoming the industry standard for etching tools. An essential parameter that must be measured in these plasmas is the density of ions, both positive and negative, formed in the plasma. In the work presented here, LIF and laser photodetachment were used to measure relative metastable chlorine ion CL{sup +}* density and temperature and absolute Cl{sup {minus}} density as a function of gas mixture.
A 1.3 {micro}m wavelength vertical-cavity surface-emitting laser (VCSEL) containing proton implanted isolation regions and a dielectric top mirror and a wafer-bonded GaAs/AlAs bottom mirror was fabricated. A room temperature pulsed threshold current density of 1.13 kA/cm{sup 2} and a threshold current of 2 mA have been demonstrated.
An efficient, scalable, parallel algorithm for treating contacts in solid mechanics has been applied to interactions between particles in smooth particle hydrodynamics (SPH). The algorithm uses three different decompositions within a single timestep: (1) a static FE-decomposition of mesh elements; (2) a dynamic SPH-decomposition of SPH particles; (3) and a dynamic contact-decomposition of contact nodes and SPH particles. The overhead cost of such a scheme is the cost of moving mesh and particle data between the decompositions. This cost turns out to be small in practice, leading to a highly load-balanced decomposition in which to perform each of the three major computational states within a timestep.
This paper is a description of work-in-progress. It describes Sandia`s program to study the basic fluid mechanics of large-scale mixing in unbounded, compressible, turbulent flows, specifically, the turbulent mixing of an axisymmetric compressible helium jet in a parallel, coflowing compressible air freestream. Both jet and freestream velocities are variable over a broad range, providing a wide range mixing layer Reynolds number. Although the convective Mach number, M{sub c}, range is currently limited by the present nozzle design to values of 0.6 and below, straightforward nozzle design changes would permit a wide range of convective Mach number, to well in excess of 1.0. The use of helium allows simulation of a hot jet due to the large density difference, and also aids in obtaining optical flow visualization via schlieren due to the large density gradient in the mixing layer. The work comprises a blend of analysis, experiment, and direct numerical simulation (DNS). There the authors discuss only the analytical and experimental efforts to observe and describe the evolution of the large-scale structures. The DNS work, used to compute local two-point velocity correlation data, will be discussed elsewhere.
Fast z-pinch implosions can convert more than 10% of the stored electrical energy in a pulsed-power accelerator into x-rays. On the Saturn pulsed-power accelerator at Sandia National Laboratories, currents of 6 to 8 MA with a risetime of less than 50 ns have been used to drive cylindrically-symmetric arrays of wires, producing x-ray energies greater than 400 kJ with x-ray pulsewidths less than 5 ns and peak x-ray powers of 75 {+-} 10 TW. Using similar loads, PBFA Z has produced > 1.5 MJ and > 150 TW of x-rays in the first four months of operation in the z-pinch mode. These x-ray energies and powers are records for laboratory x-ray production. The x-ray output can be thermalized into a near-Planckian x-ray source by containing it within a cylindrical radiation case (a hohlraum). These energetic, intense, large volume, long-lived hohlraum x-ray sources have recently been used for ICF-relevant ablator physics experiments and offer the potential for performing many new basic physics and fusion-relevant experiments.
The authors define two simple metrics for accuracy of models built from range imaging information. They apply the metric to a model built from a recent range image taken at the Laser Radar Development and Evaluation Facility (LDERF), Eglin AFB, using a Scannerless Range Imager (SRI) from Sandia National Laboratories. They also present graphical displays of the residual information produced as a byproduct of this measurement, and discuss mechanisms that these data suggest for further improvement in the performance of this already impressive SRI.
The intent of this tutorial is to overview the technology of multi-level polysilicon surface micromachining, to present examples of devices which fully utilize this level of complexity, and to discuss what they believe to be significant issues which are not fully resolved. Following this intent, the tutorial consists of four sections. The first is an introduction and description of multi-level polysilicon surface micromachining and its potential benefits. Specifically, the inclusion of a third deposited layer of mechanical polysilicon greatly extends the degree of complexity available for micromechanism design. The second section introduces wafer planarization by CMP as a process tool for surface micromachining. The third section presents examples of actuated geared micromechanisms which require the multi-level fabrication process. Demonstration of actuation mechanisms coupled to external devices are illustrated. Finally, polysilicon surface micromachining fabrication technology has reached a level where many device designs, for the most part, can be embodied in the technology to produce a mechanical construct which provides the desired function. When designed properly, the fabricated mechanical element, if free to operate, will produce the desired function. However, one set of issues which can hinder or prevent operation are related to the post-fabricated device surfaces. These surface issues; namely, stiction, friction, and wear, are emphasized in the final section as a major hindrance to realizing the full potential of surface micromachined devices.
The unattended sensing of stationary (i.e. non-mobile) targets is important in applications ranging from counter-proliferation to law enforcement. With stationary targets, sources of seismic, acoustic, and electro-magnetic emissions can potentially be used to detect, identify, and locate the target. Stationary targets have considerably different sensing requirements than the traditional mobile-target unattended ground sensor applications. This paper presents the novel features and requirements of a system for sensing stationary targets. In particular, issues associated with long-listen time signal processing for signal detection, and array processing techniques for signal localization are presented. Example data and signal processing outputs from a stationary target will be used to illustrate these issues. The impact on sensor, electronic signal processing, battery subsystem, and communication requirements will also be discussed. The paper will conclude with a detailed comparison between mobile-target and stationary-target unattended ground sensor architectures.
The authors present the growth and characterization of vertical-cavity surface emitting lasers (VCSELs) from visible to near-infrared wavelength grown by metalorganic vapor phase epitaxy. Discussions on the growth issue of VCSEL materials include the control on growth rate and composition using an in situ normal-incidence reflectometer, optimization of ultra-high material uniformity, and comprehensive p- and n-type doping study in AlGaAs by CCl{sub 4} and Si{sub 2}H{sub 6} over the entire Al composition range. They will also demonstrate the recent achievements of selectively-oxidized VCSELs which include the first room-temperature continuous-wave demonstration of all-AlGaAs 700-nm red VCSELs, high-performance n-side up 850-nm VCSELs, and low threshold current and low-threshold voltage 1.06 {micro}m VCSELs using InGaAs/GaAsP strain-compensated quantum wells.
This work builds upon established Sandia intelligent systems technology to develop a unique approach for the integration of intelligent system control into the US Highway and urban transportation systems. The Sandia developed concept of the COPILOT controller integrates a human driver with computer control to increase human performance while reducing reliance on detailed driver attention. This research extends Sandia expertise in sensor based, real-time control of robotics systems to high speed transportation systems. Knowledge in the form of maps and performance characteristics of vehicles provides the automatic decision making intelligence needed to plan optimum routes, maintain safe driving speeds and distances, avoid collisions, and conserve fuel.
Sandia National Laboratories, New Mexico, conducts the Energy Storage Systems Program, which is sponsored by the US Department of Energy`s Office of Utility Technologies. The goal of this program is to assist industry in developing cost-effective energy storage systems as a resource option by 2000. Sandia is responsible for the engineering analyses, contracted development, and testing of energy storage systems for stationary applications. This report details the technical achievements realized during fiscal year 1996.
Hydraulic fracturing tests were integrated with hydrologic tests to estimate the conditions under which gas pressure in the disposal rooms in the Waste Isolation Pilot Plant, Carlsbad, NM (WIPP) will initiate and advance fracturing in nearby anhydrite interbeds. The measurements were made in two marker beds in the Salado formation, MB139 and MB140, to explore the consequences of existing excavations for the extrapolation of results to undisturbed ground. The interpretation of these measurements is based on the pressure-time records in two injection boreholes and several nearby hydrologic observation holes. Data interpretations were aided by post-test borehole video surveys of fracture traces that were made visible by ultraviolet illumination of fluorescent dye in the hydraulic fracturing fluid. The conclusions of this report relate to the upper- and lower-bound gas pressures in the WIPP, the paths of hydraulically and gas-driven fractures in MB139 and MB140, the stress states in MB139 and MB140, and the probable in situ stress states in these interbeds in undisturbed ground far away from the WIPP.
The cited paper estimates the consequences that might occur should a purpose-built ship transporting Vitrified High Level Waste (VHLW) be involved in a severe collision that causes the VHLW canisters in one Type-B package to spill onto the floor of a major ocean fishing region. Release of radioactivity from VHLW glass logs, failure of elastomer cask seals, failure of VHLW canisters due to stress corrosion cracking (SCC), and the probabilities of the hypothesized accident scenario, of catastrophic cask failure, and of cask recovery from the sea are all discussed.
The objective is to assess the occurrence of nonplanar distortions of hemes and other tetrapyrroles in proteins and to determine the biological function of these distortions. Recently, these distortions were found by us to be conserved among proteins belonging to a functional class. Conservation of the conformation of the heme indicates a possible functional role. Researchers have suggested possible mechanisms by which heme distortions might influence biological properties; however, no heme distortion has yet been shown conclusively to participate in a structural mechanism of hemoprotein function. The specific aims of the proposed work are: (1) to characterize and quantify the distortions of the hemes in all of the more than 300 hemoprotein X-ray crystal structures in terms of displacements along the lowest-frequency normal coordinates, (2) to determine the structural features of the protein component that generate and control these nonplanar distortions by using spectroscopic studies and molecular-mechanics calculations for the native proteins, their mutants and heme-peptide fragments, and model porphyrins, (3) to determine spectroscopic markers for the various types of distortion, and, finally, (4) to discover the functional significance of the nonplanar distortions by correlating function with porphyrin conformation for proteins and model porphyrins.
Improved characterization and process control is important to many Sandia and DOE programs related to manufacturing. Many processes/structures are currently under-characterized including thin film growth, corrosion and semiconductor structures, such as implant profiles. A sensitive tool is required that is able to provide lateral and vertical imaging of the electromagnetic properties of a sample. The confocal resonator is able to characterize the surface and near-surface impedance of materials. This device may be applied to a broad range of applications including in situ evaluation of thin film processes, physical defect detection/characterization, the characterization of semiconductor devices and corrosion studies. In all of these cases, the technology should work as a real-time process diagnostic or as a feedback mechanism regarding the quality of a manufacturing process. This report summarizes the development and exploration of several diagnostic applications.
A micro electro-hydrodynamic (EHD) injection pump has been developed using laser micromachining technology. Two designs have been fabricated, tested, and evaluated. The first design has two silicon parts with KOH-etched wells which are stacked on the top of each other. The wells are etched into one side of the wafer, and gold is deposited on the other side to serve as the pump electrodes. A Nd:YAG laser is used to drill an array of circular holes in the well region of both silicon parts. This creates a grid distribution with a square pattern. Next the well regions of the silicon parts are aligned, and the parts are bonded together using a Staystik thermoplastic. Together, the bonded siliconpart form the pump. The pump unit is then mounted into a ceramic package with a large hole drilled in the bottom of the package to permit fluid flow. Aluminum ribbon wire bonds are used to connect the pump electrodes to the package leads. Isolation of the metallization and wires is achieved by filling the package cavity and coating the wires with polyimide. When a voltage is applied to the electrodes, ions are injected into the working fluid, such as an organic solvent, thus inducing flow. The second design has the silicon parts oriented {open_quote}back-to-back{close_quote} and bonded together with Stayform. A {open_quote}back-to-back{close_quote} design will decrease the grid distance so that a smaller voltage is required for pumping. Experimental results have demonstrated that this micro pump can achieved a pressure head of about 287 Pa with an applied voltage of 120 V.
This report documents, demonstrates, evaluates, and provides theoretical justification for methods used to convert experimental data into relative permeability relationships. The report facilities accurate determination of relative permeabilities of anhydride rock samples from the Salado Formation at the Waste Isolation Pilot Plant (WIPP). Relative permeability characteristic curves are necessary for WIPP Performance Assessment (PA) predictions of the potential for flow of waste-generated gas from the repository and brine flow into repository. This report follows Christiansen and Howarth (1995), a comprehensive literature review of methods for measuring relative permeability. It focuses on unsteady-state experiments and describes five methods for obtaining relative permeability relationships from unsteady-state experiments. Unsteady-state experimental methods were recommended for relative permeability measurements of low-permeability anhydrite rock samples form the Salado Formation because these tests produce accurate relative permeability information and take significantly less time to complete than steady-state tests. Five methods for obtaining relative permeability relationships from unsteady-state experiments are described: the Welge method, the Johnson-Bossler-Naumann method, the Jones-Roszelle method, the Ramakrishnan-Cappiello method, and the Hagoort method. A summary, an example of the calculations, and a theoretical justification are provided for each of the five methods. Displacements in porous media are numerically simulated for the calculation examples. The simulated product data were processed using the methods, and the relative permeabilities obtained were compared with those input to the numerical model. A variety of operating conditions were simulated to show sensitivity of production behavior to rock-fluid properties.
A multispectral ultraviolet (UV) fluorescence imaging fluorometer and a pulsed molecular beam laser fluorometer were developed to detect volatile organic compounds of interest in environmental monitoring and drug interdiction applications. The UV fluorescence imaging fluorometer is a relatively simple instrument which uses multiple excitation wavelengths to measure the excitation/emission matrix for irradiated samples. Detection limits in the high part-per-million to low part-per-million range were measured for a number of volatile organic vapors in the atmosphere. Detection limits in the low part-per-million range were obtained using cryogenic cooling to pre-concentrate unknown samples before introducing them into the imaging fluorometer. A multivariate analysis algorithm was developed to analyze the excitation/emission matrix and used to determine the relative concentrations of species in computer synthesized mixtures containing up to five organic compounds. Analysis results demonstrated the utility of multispectral UV fluorescence in analytical measurements. A transportable UV fluorescence imaging fluorometer was used in two field tests. Field test results demonstrated that detection limits in the part-per-billion range were needed to reliably identify volatile organic compounds in realistic field test measurements. The molecular beam laser fluorometer, a more complex instrument with detection limits in the part-per-billion to part-per-trillion range, was therefore developed to satisfy detection sensitivity requirements for field test measurements. High-resolution spectroscopic measurements made with the molecular beam laser fluorometer demonstrated its utility in identifying volatile organic compounds in the atmosphere.
This report describes the WIPP 1 test case studied as part of INTRAVAL, an international project to study validation of geosphere transport models. The WIPP 1 test case involved simulation of measured brine-inflow rates to boreholes drilled into the halite strata surrounding the Waste Isolation Pilot Plant repository. The goal of the test case was to evaluate the use of Darcy`s law to describe brine flow through halite. The general approach taken was to try to obtain values of permeability and specific capacitance that would be: (1) consistent with other available data and (2) able to provide reasonable simulations of all of the brine-inflow experiments performed in the Salado Formation. All of the teams concluded that the average permeability of the halite strata penetrated by the holes was between approximately 10{sup {minus}22} and 10{sup {minus}21} m{sup 2}. Specific capacitances greater than 10{sup {minus}10} Pa{sup {minus}1} are inconsistent with the known constitutive properties of halite and are attributed to deformation, possibly ongoing, of the halite around the WIPP excavations. All project teams found that Darcy-flow models could replicate the experimental data in a consistent and reasonable manner. Discrepancies between the data and simulations are attributed to inadequate representation in the models of processes modifying the pore-pressure field in addition to the experiments themselves, such as ongoing deformation of the rock around the excavations. Therefore, the conclusion from the test case is that Darcy-flow models can reliably be used to predict brine flow to WIPP excavations, provided that the flow modeling is coupled with measurement and realistic modeling of the pore-pressure field around the excavations. This realistic modeling of the pore-pressure field would probably require coupling to a geomechanical model of the stress evolution around the repository.
The ability of an open-path, fourier-transform infrared spectrometer to detect vehicle exhaust emissions approximately 3 meters above the roadway surface at a busy Albuquerque suburban intersection was evaluated in this study. Multiple measurements of carbon monoxide and carbon dioxide were carried out over pathlengths up to 100 meters during the morning commute period on multiple days in the summer of 1993. The carbon monoxide to fuel carbon ratio was computed from all spectral data in order to derive a vehicle fleet average ratio. The data were determined to be normally distributed with an overall carbon monoxide-fuel carbon ratio of 0.15. The 95% confidence interval about the mean was {+-} 0.009. Day-to-day variation of the mean ratio was determined to be on the order of 3%. The results indicate that anticipated reductions in carbon monoxide emissions following the implementation of a winter-season oxygenated fuel program could be reliably detected with an open-path fourier transform spectrometer. The periodic use of such an instrument may offer a cost-effective means of generating a city-wide carbon monoxide emission budget for vehicles sources.
In this paper, preliminary results on the use of active chatter control in a new type of milling machine is presented. It is expected that this machine will cut metal at twice the rate of conventional machines without an appreciable increase in cost. Performance enhancements are achieved by the integration of active feedback control into an existing machine structure. To reduce computational burden, decoupled control is proposed. Extensive simulations have shown that significant performance enhancements are achievable.
This report summarizes the development of in situ spectral reflectance as a tool for improving the quality, reproducibility, and yield of device structures grown from compound semiconductors. Although initially targeted at MBE (Molecular Beam Epitaxy) machines, equipment difficulties forced the authors to test most of their ideas on a MOCVD (Metal Organic Chemical Vapor Deposition) reactor. A pre-growth control strategy using in situ reflectance has led to an unprecedented demonstration of process control on one of the most difficult device structures that can be grown with compound semiconductor materials. Hundreds of vertical cavity surface emitting lasers (VCSEL`s) were grown with only {+-} 0.3% deviations in the Fabry-Perot cavity wavelength--a nearly ten-fold improvement over current calibration methods. The success of the ADVISOR (Analysis of Deposition using Virtual Interfaces and Spectroscopic Optical Reflectance) method has led to a great deal of interest from the commercial sector, including use by Hewlett Packard and Honeywell. The algorithms, software and reflectance design are being evaluated for patents and/or license agreements. A small company, Filmetrics, Inc., is incorporating the ADVISOR analysis method in its reflectometer product.
Silicones [polydimethylsiloxane (PDMS) polymers] are environmentally safe, nonflammable, weather resistant, thermally stable, low T{sub g} materials which are attractive for general elastomer applications because of their safety and their performance over a wide temperature range. However, PDMS is inherently weak due to its low glass transition temperature (T{sub g}) and lack of stress crystallization. The major goal of this project was to create a family of reinforced elastomers based on silsesquioxane/PDMS networks. Polydimethylsiloxane-based (PDMS) composite materials containing a variety of alkylene-arylene-bridged polysilsesquioxanes were synthesized in order to probe short chain and linkage effects in bimodal polymer networks. Monte Carlo simulations on the alkylene-bridged silsesquioxane/PDMS system predicted that the introduction of the silsesquioxane short chains into the long chain PDMS network would have a significant reinforcing effect on the elastomer. The silsesquioxane-PDMS networks were synthesized and evaluated. Analysis of the mechanical properties of the resulting materials indicated that use of the appropriate silisesquioxane generated materials with greatly enhanced properties. Arylene and activated alkylene systems resulted in materials that showed superior adhesive strength for metal-to-metal adhesion.
The BES Materials Sciences Program has the central theme of Scientifically Tailored Materials. The major objective of this program is to combine Sandia`s expertise and capabilities in the areas of solid state sciences, advanced atomic-level diagnostics and materials synthesis and processing science to produce new classes of tailored materials as well as to enhance the properties of existing materials for US energy applications and for critical defense needs. Current core research in this program includes the physics and chemistry of ceramics synthesis and processing, the use of energetic particles for the synthesis and study of materials, tailored surfaces and interfaces for materials applications, chemical vapor deposition sciences, artificially-structured semiconductor materials science, advanced growth techniques for improved semiconductor structures, transport in unconventional solids, atomic-level science of interfacial adhesion, high-temperature superconductors, and the synthesis and processing of nano-size clusters for energy applications. In addition, the program includes the following three smaller efforts initiated in the past two years: (1) Wetting and Flow of Liquid Metals and Amorphous Ceramics at Solid Interfaces, (2) Field-Structured Anisotropic Composites, and (3) Composition-Modulated Semiconductor Structures for Photovoltaic and Optical Technologies. The latter is a joint effort with the National Renewable Energy Laboratory. Separate summaries are given of individual research areas.