The study of gain properties in group-III nitride quantum wells is complicated by several factors. In view of this, an approach is presented that involves a first-principles bandstructure calculation, the results of which are incorporated into a microscopic laser theory. The band structure calculation applies a density-functional method. This method provides a single analytical model for computing the group-II nitride material properties, thus ensuring consistency in the values for the different bandstructure parameters, and circumventing the discrepancies present in the literature due to different experimental conditions, or different computational methods. With a complete set of the relevant material parameters, it is possible to study the effects of strain and quantum confinement.
Monochromatic imaging was used to investigate the excited-state density distributions of Fe and Fe+ in the inter-electrode gap region of a 3,100 A dc metal vapor arc burning between molten iron surfaces in a vacuum arc furnace. Multiple images were acquired at four wavelengths. The images were corrected and Abel inverted to yield the absolute radial intensity distributions for Fe and Fe+ in the inter-electrode gap region. The results show a structured, axisymmetric plasma consisting of a high density 'core' of Fe+ emitters centered between the electrode surfaces situated against a relatively broad, flat excited-state Fe distribution.
The Smart Gun Technology Project has a goal to eliminate the capability of an unauthorized user from firing a law enforcement officer`s firearm by implementing {open_quote}smart{close_quote} technologies. Smart technologies are those that can in some manner identify an officer. This report will identify, describe, and grade various technologies as compared to the requirements that were obtained from officers. This report does not make a final recommendation for a smart gun technology, nor does it give the complete design of a smart gun system.
Numerical studies have been made of an infiltration experiment at Fran Ridge using the TOUGH2 code to aid in the selection of computational models for performance assessment. The exercise investigates the capabilities of TOUGH2 to model transient flows through highly fractured tuff and provides a possible means of calibration. Two distinctly different conceptual models were used in the TOUGH2 code, the dual permeability model and the equivalent continuum model. The infiltration test modeled involved the infiltration of dyed ponded water for 36 minutes. The 205 gallon filtration of water observed in the experiment was subsequently modeled using measured Fran Ridge fracture frequencies, and a specified fracture aperture of 285 {mu}m. The dual permeability formulation predicted considerable infiltration along the fracture network, which was in agreement with the experimental observations. As expected, minimal fracture penetration of the infiltrating water was calculated using the equivalent continuum model, thus demonstrating that this model is not appropriate for modeling the highly transient experiment. It is therefore recommended that the dual permeability model be given priority when computing high-flux infiltration for use in performance assessment studies.
6th Symposium on Multidisciplinary Analysis and Optimization
Campbell, J.E.; Painton, L.A.
This paper examines a novel optimization technique called genetic algorithms and its application to the optimization of reliability allocation strategies. Reliability allocation should occur in the initial stages of design, when the objective is to determine an optimal breakdown or allocation of reliability to certain components or subassemblies in order to meet system objectives. The reliability allocation optimization is applied to the design of a cluster tool, a highly complex piece of equipment used in semiconductor manufacturing. The problem formulation is presented, including decision variables, performance measures and constraints, and genetic algorithm parameters. Piecewise “effort curves” specifying the amount of effort required to achieve a certain level of reliability for each component or subassembly are defined. The genetic algorithm evolves or picks those combinations of “effort” or reliability levels for each component which optimize the objective of maximizing Mean Time Between Failures while staying within a budget. The results show that the genetic algorithm is very efficient at finding a set of robust solutions. A time history of the optimization is presented, along with histograms of the solution space fitness, MTBF, and cost for comparative purposes.
Conference Proceedings from the International Symposium for Testing and Failure Analysis
Liang, A.Y.
We present the results of recent failure analysis of an advanced, 0.5 um, fully planarized, triple metallization CMOS technology. A variety of failure analysis (FA) tools and techniques were used to localize and identify defects generated by wafer processing. These include light (photon) emission microscopy (LE), fluorescent microthermal imaging (FMI), focused ion beam cross sectioning, SEM/voltage contrast imaging, resistive contrast imaging (RCI), and e-beam testing using an IDS-5000 with an HP 82000. The defects identified included inter- and intra-metal shorts, gate oxide shorts due to plasma processing damage, and high contact resistance due to the contact etch and deposition process. Root causes of these defects were determined and corrective action was taken to improve yield and reliability.
Polysilicon surface micromachining is a technology for manufacturing Micro-Electro-Mechanical Systems (MEMS) which has, as its basis, the manufacturing methods and tool sets used to manufacture the integrated electronic circuit. This paper describes a three-level mechanical-polysiiicon surface-micromachining technology and includes a discussion of the advantages of this level of process complexity along with issues which affect device fabrication and performance. Historically, the primary obstacles to multi-level polysilicon fabrication were related to the severe wafer topography generated by the repetition of film depositions and etching. The introduction of Chemical Mechanical Polishing (CMP) to surface micromachining has largely removed these issues and opened significant avenues for device complexity. Several examples of three-level devices with the benefits of CMP are presented. Of primary hindrance to the widespread use of polysilicon surface micromachining, and in particular microactuation mechanisms, are issues related to the device surfaces. The closing discussion examines the potential of several latter and postfabrication processes to circumvent or to directly alleviate the surface problems.
We apply a number of complementary characterization techniques including electron paramagnetic resonance, optical absorption, and photoluminescence spectroscopies to characterize a wide range of different ZnO phosphor powders. We generally observe a good correlation between the 510-nm green emission intensity and the density of paramagnetic isolated oxygen vacancies. In addition, both quantities are found to peak at a free-carrier concentration ne, of about 1.4×1018 cm-3. We also find that the green emission intensity can be strongly influenced by free-carrier depletion at the particle surface, especially for small particles and/or low doping. Our data suggest that the green PL in ZnO phosphors is due to the recombination of electrons in singly occupied oxygen vacancies with photoexcited holes in the valence band.
Silicon solar cell efficiencies of 17.1%, 16.4%, 14.8%, and 14.9% have been achieved on FZ, Cz, multicrystalline (mc-Si), and dendritic web (DW) silicon, respectively, using simplified, cost-effective rapid thermal processing (RTP). These represent the highest reported efficiencies for solar cells processed with simultaneous front and back diffusion with no conventional high-temperature furnace steps. Appropriate diffusion temperature coupled with the added in-situ anneal resulted in suitable minority-carrier lifetime and diffusion profiles for high-efficiency cells. The cooling rate associated with the in-situ anneal can improve the lifetime and lower the reverse saturation current density (Jo), however, this effect is material and base resistivity specific. PECVD antireflection (AR) coatings provided low reflectance and efficient front surface and bulk defect passivation. Conventional cells fabricated on FZ silicon by furnace diffusions and oxidations gave an efficiency of 18.8% due to greater short wavelength response and lower Jo.
With the eventual phase-out of chlorofluorocarbons and hydrochlorofluorocarbons, and restrictive regulations concerning the use of other volatile organic compounds as cleaning solvents, it is essential to seek new, environmentally acceptable cleaning processes. We are investigating supercritical carbon dioxide (CO2) as an alternative solvent for precision cleaning of machined metal parts in governmental and industrial cleaning processes. The compatibility of metals in supercritical-fluid cleaning media with respect to corrosion must be addressed. In this work, a screening study of the corrosive effects of supercritical CO2 and several supercritical cosolvents on selected metals was conducted. Sample coupons of stainless steel (grades 304LSS, 316SS), aluminum (grades 2024, 6061, 7075), carbon steel (1018), and copper (CDA 101) were statically exposed to pure supercritical CO2, water-saturated supercritical CO2, 10 wt % methanol/CO2 cosolvent, and 4 wt % tetrahydrofurfuryl alcohol (THFA)/CO2 at 24,138 kPa (3500 psig) and 323 K (50 °C) for 24 h. Gravimetric analysis and magnified visual inspection of the coupons were performed before and after the exposure tests. Surface analyses including electron microprobe analysis (EMPA), X-ray photoelectron spectroscopy (XPS), and Auger electron spectroscopy (AES) were done where visual and gravimetric changes were indicative of corrosive attack. The metal alloys were found to be compatible with the supercritical test media barring a few exceptions. Corrosive attack was observed on 1018 carbon steel in the water-saturated CO2 environment, and also on 2024 aluminum and CDA 101 copper, both in the 10 wt % methanol-CO2 cosolvent. The results of all compatibility testing are reported, and hypotheses are formed in an attempt to explain possible corrosion mechanisms.
A survey of existing data has been completed in order to examine the hazards to people exposed on the ground and to in-flight aircraft by debris produced during high-altitude, rocket-boosted flight tests. These data were then analyzed to quantify the particle sizes and energy levels below which the fragments no longer pose a hazard. The survey results are presented here and recommendations made regarding the minimum energy levels and minimum particle size that need be considered in a flight safety analysis.
Crystal lattices are infinite periodic graphs that occur naturally in a variety of geometries and which are of fundamental importance in polymer science. Discrete models of protein folding use crystal lattices to define the space of protein conformations. Because various crystal lattices provide discretizations of the same physical phenomenon, it is reasonable to expect that there will exist "invariants" across lattices that define fundamental properties of the protein folding process; an invariant defines a property that transcends particular lattice formulations. This paper identifies two classes of invariants, defined in terms of sublattices that are related to the design of algorithms for the structure prediction problem. The first class of invariants is used to define a master approximation algorithm for which provable performance guarantees exist. This algorithm can be applied to generalizations of the hydrophobic-hydrophilic model that have lattices other than the cubic lattice, including most of the crystal lattices commonly used in protein folding lattice models. The second class of invariants applies to a related lattice model. Using these invariants, we show that for this model the structure prediction problem is intractable across a variety of threedimensional lattices. It turns out that these two classes of invariants are respectively sublattices of the two-and three-dimensional square lattice. As the square lattices are the standard lattices used in empirical protein folding studies, our results provide a rigorous confirmation of the ability of these lattices to provide insight into biological phenomenon. Our results are the first in the literature that identify algorithmic paradigms for the protein structure prediction problem that transcend particular lattice formulations.
This is a brochure about the Solar Thermal Design Assistance Center of Sandia National Laboratories: technical assistance, testing, technology development, education, and customer services
This small booklet tells the profile, mission, operations, services, and data base of Sandia National Laboratories Photovoltaic Design Assistance Center
Reactor power supplies offer many attractive characteristics for lunar surface applications. The Topaz II reactor resulted from an extensive development program in the former Soviet Union. Flight quality reactor units remain from this program and are currently under evaluation in the United States. This paper examines the potential for applying the Topaz II, originally developed to provide spacecraft power, as a lunar surface power supply.
In accordance with the Nuclear Regulatory Commission regulation regarding groundwater travel times at geologic repositories, various models of unsaturated flow in fractured tuff have been developed and implemented to assess groundwater travel times at the potential repository at Yucca Mountain, Nevada. Kaplan used one-dimensional models to describe the uncertainty and sensitivity of travel times to various processes at Yucca Mountain. Robey and Arnold et al. used a two-dimensional equivalent continuum model (ECM) with inter- and intra-unit heterogeneity in an attempt to assess fast-flow paths through the unsaturated, fractured tuff at Yucca Mountain (GWTT-94). However, significant flow through the fractures in previous models was not simulated due to the characteristics of the ECM, which requires the matrix to be nearly saturated before flow through the fractures is initiated. In the current study (GWTT-95), four two-dimensional cross-sections at Yucca Mountain are simulated using both the ECM and dual-permeability (DK) models. The properties of both the fracture and matrix domains are geostatistically simulated, yielding completely heterogeneous continua. Then, simulations of flow through the four cross-sections are performed using spatially nonuniform infiltration boundary conditions. Steady-state groundwater travel times from the potential repository to the water table are calculated.
The next total-system performance-assessment (TSPA) analyses are designed to aid DOE in performing an ``investment analysis`` for Yucca Mountain. This TSPA must try to bound the uncertainties for several issues that will contribute to the decision whether the US should proceed with the development of a nuclear-waste repository at Yucca Mountain. Because site-characterization experiments and data collection will continue for the foreseeable future, the next TSPA (called TSPA-IA) will again only be able to use partially developed models and partial data sets. In contrast to previous analyses however, TSPA-IA must address more specific questions to be of assistance to the investment-analysis deliberations.
Unsaturated flow has been modeled through four cross-sections at Yucca Mountain, Nevada, for the purpose of determining groundwater particle travel times from the potential repository to the water table. This work will be combined with the results of flow modeling in the saturated zone for the purpose of evaluating the suitability of the potential repository under the criteria of 10CFR960. One criterion states, in part, that the groundwater travel time (GWTT) from the repository to the accessible environment must exceed 1,000 years along the fastest path of likely and significant radionuclide travel. Sensitivity analyses have been conducted for one geostatistical realization of one cross-section for the purpose of (1) evaluating the importance of hydrological parameters having some uncertainty and (2) examining conceptual models of flow by altering the numerical implementation of the conceptual model (dual permeability (DK) and the equivalent continuum model (ECM). Results of comparisons of the ECM and DK model are also presented in Ho et al.
The performance of waste packages containing high-level nuclear wastes at underground repositories such as the potential repository at Yucca Mountain, Nevada, depends, in part, on the thermodynamic environment immediately surrounding the buried waste packages. For example, degradation of the waste packages can be caused by corrosive and microbial processes, which are influenced by both the relative humidity and temperature within the emplacement drifts. In this paper, the effects of conduction, convection, and radiation are investigated for a heat-generating waste package in an empty-drift. Simulations explicitly modeling radiation from the waste package to the drift wall are compared simulations using only conduction. Temperatures, relative humidities, and vapor mass fractions are compared at various locations within the drift. In addition, the effects of convection on relative humidity and moisture distribution within the drift are presented.
The Radiological Environment Modeling System (REMS) quantifies dose to humans in radiation environments using the IGRIP (Interactive Graphical Robot Instruction Program) and Deneb/ERGO (Ergonomics) simulation software products. These commercially available products are augmented with custom C code to provide the radiation exposure information to and collect the radiation dose information from the workcell simulations. The emphasis of this paper is on the IGRIP and Deneb/ERGO parts of REMS, since that represents the extension to existing capabilities developed by the authors. Through the use of any radiation transport code or measured data, a radiation exposure input database may be formulated. User-specified IGRIP simulations utilize these database files to compute and accumulate dose to human devices (Deneb`s ERGO human) during simulated operations around radiation sources. Timing, distances, shielding, and human activity may be modeled accurately in the simulations. The accumulated dose is recorded in output files, and the user is able to process and view this output. REMS was developed because the proposed reduction in the yearly radiation exposure limit will preclude or require changes in many of the manual operations currently being utilized in the Weapons Complex. This is particularly relevant in the area of dismantlement activities at the Pantex Plant in Amarillo, TX. Therefore, a capability was needed to be able to quantify the dose associated with certain manual processes so that the benefits of automation could be identified and understood.
A technique called the Natural Excitation Technique or has been developed to response extract response parameters from large operational structure when subjected to random and unmeasured forces such as wind, road noise, aerodynamics, or waves. Six applications of NExT to ambient excitation testing and NExT analysis are surveyed in this paper with a minimum of technical detail. In the first application, NExT was applied to a controlled-yaw Horizontal-Axis Wind Turbine (HAWT). By controlling the yaw degree of freedom an important class of rotating coordinate system effects are reduced. A new shape extraction procedure was applied to this data set with good results. The second application was to a free-yaw HAWT. The complexity of the response has prompted further analytical studies and the development of a specialized visualization package. The third application of NExT was to a parked three-bladed Vertical-Axis Wind Turbine (VAWT) in which traditional modal testing could not excite all modes of interest. The shape extraction process used cross-correlation functions directly in a time-domain shape-fitting routine. The fourth application was to ground transportation systems. Ongoing work to improve driver and passenger comfort in tractor-trailer vehicles and to refine automobile body and tire models will use NExT. NExT has been used to process ambient vibration data for Finite Element Model correlation and is being used to study Structural Health Monitoring with ambient excitation. Shape fitting was performed using amplitude and phase information taken directly from the cross-spectra. The final application is to an offshore structure. This work is on-going, however initial studies have found a high-modal density, high noise content, and sparse data set.
Future advances in the application of photonic interconnects will involve the insertion of parallel-channel links into Multi-Chip Modules (MCMS) and board-level parallel connections. Such applications will drive photonic link components into more compact forms that consume far less power than traditional telecommunication data links. These will make use of new device-level technologies such as vertical cavity surface-emitting lasers and special low-power parallel photoreceiver circuits. Depending on the application, these device technologies will often be monolithically integrated to reduce the amount of board or module real estate required by the photonics. Highly parallel MCM and board-level applications will also require simplified drive circuitry, lower cost, and higher reliability than has been demonstrated in photonic and optoelectronic technologies. An example is found in two-dimensional point-to-point array interconnects for MCM stacking. These interconnects are based on high-efficiency Vertical Cavity Surface Emitting Lasers (VCSELs), Heterojunction Bipolar Transistor (HBT) photoreceivers, integrated micro-optics, and MCM-compatible packaging techniques. Individual channels have been demonstrated at 100 Mb/s, operating with a direct 3.3V CMOS electronic interface while using 45 mW of electrical power. These results demonstrate how optoelectronic device technologies can be optimized for low-power parallel link applications.
Most routing problems depend on several important variables: transport distance, population exposure, accident rate, mandated roads (e.g., HM-164 regulations), and proximity to emergency response resources are typical. These variables may need to be minimized or maximized, and often are weighted. `Objectives` to be satisfied by the analysis are thus created. The resulting problems can be approached by combining spatial analysis techniques from geographic information systems (GIS) with multiobjective analysis techniques from the field of operations research (OR); we call this hybrid multiobjective spatial analysis` (MOSA). MOSA can be used to discover, display, and compare a range of solutions that satisfy a set of objectives to varying degrees. For instance, a suite of solutions may include: one solution that provides short transport distances, but at a cost of high exposure; another solution that provides low exposure, but long distances; and a range of solutions between these two extremes.
Three and four-layer backpropagation artificial neural networks have been used to predict the power output of a liquid metal reflux solar receiver. The networks were trained using on-sun test data recorded at Sandia National Laboratories in Albuquerque, New Mexico. The preliminary results presented in this paper are a comparison of how different size networks train on this particular data. The results give encouragement that it will be possible to predict output power of a liquid metal receiver under a variety of operating conditions using artificial neural networks.
We have conducted a real time, two-dimensional light scattering study of the nonlinear dynamics of field-induced structures in an electrorheological fluid subjected to oscillatory shear. We have developed a kinetic chain model of the observed dynamics by considering the response of a fragmenting/aggregating particle chain to the prevailing hydrodynamic and electrostatic forces. This structural theory is then used to describe the nonlinear rheology of ER fluids.
This paper describes recent work to make high quality quartz gauge (temporal and spatial) shock wave measurements in a pulsed ion beam environment. Intense ion beam radiation, nominally 1 MeV protons, was deposited into material samples instrumented with shunted quartz gauges adjacent to the ion deposition zone. Fluence levels were chosen to excite three fundamentally different material response modes (1) strong vapor, (2) combined vapor and melt phase and (3) thermoelastic material response. A unique quartz gauge design was utilized that employed printed circuit board (PCB) technology to facilitate electrical shielding, ruggedness, and fabrication @e meeting the essential one dimensional requirements of the characterized Sandia shunted quartz gauge. Shock loading and unloading experiments were conducted to evaluate the piezoelectric response of the coupled quartz gauge/PCB transducer. High fidelity shock wave profiles were recorded at the three ion fluence levels providing dynamic material response data for vapor, melt and solid material phases.
Terminal propagation is a method developed in the circuit placement community for adding constraints to graph partitioning problems. This paper adapts and expands this idea, and applies it to the problem of partitioning data structures among the processors of a parallel computer. We show how the constraints in terminal propagation can be used to encourage partitions in which messages are communicated only between architecturally near processors. We then show how these constraints can be handled in two important partitioning algorithms, spectral bisection and multilevel-KL. We compare the quality of partitions generated by these algorithms to each other and to Partitions generated by more familiar techniques.
The viscous response of electrorheological fluids is usually manipulated through the use of DC or uniaxial AC electric fields. The result is that fibrillated structures parallel to the field form in a quiescent fluid; the distortion of such structures in a flow determines the enhanced viscous response, at least at low and moderate flow rates. We have conducted preliminary studies of electrorheological response in a different field configurations rotating electric field. With respect to the uniaxial AC case. there are two new developments in this type of field. The structures formed are disk-like, in the plane of the rotating field. Furthermore, the structures rotate either with or against the field, depending on the dielectric or conductivity contrast with the surrounding fluid.
This document presents details of the verification process of the RADTRAN computer code which was established for the calculation of risk estimates for radioactive materials transportation by highway, rail, air, and waterborne modes.
Because of the complexity, volume of data and calculations required, one preferred analytical tool to perform transportation risk assessments is the RADTRAN computer code. RADTRAN combines user-determined material, packaging, transportation, demographic and meteorological factors, with health physics data to calculate expected radiological consequences and accident risk from transporting radioactive materials by all commercial modes including truck, rail, ship, air and barge. The computer code consists of two major modules for each transport mode: the incident-free module, in which doses from normal transport are calculated; and the accident module, in which dose consequences and probabilities are evaluated to generate risk estimates. The purpose of this presentation is to describe the development of a standardized procedure to perform transportation radiological risk assessments employing conventional spreadsheet programs to automate generation of RADTRAN input files and post-processing analysis of the resulting output.
This document presents details of the environmental activities that occurred during 1994 at Sandia National Laboratories. Topics include: Background about Sandia; radiation facts; sources of radiation; environmental monitoring; discussion of radiation detectors; radioactive waste management; environmental restoration; and quality assurance.
The mission of the American Textile (AMTEX{trademark}) Partnership is to engage the unique technical resources of the Department of Energy National Laboratories to work with the US Integrated Textile Complex (US ITC) and research universities to develop and deploy technologies that will increase the competitiveness of the US ITC. The objectives of the Demand Activated Manufacturing Architecture (DAMA) project of AMTEX are: (1) to determine strategic business structure changes for the US ITC; (2) to establish a textile industry electronic marketplace, (3) to provide methods for US ITC education ad implementation of an electronic marketplace. The Enterprise Modeling and Simulation Task of DAMA is focusing on the first DAMA goal as described in another paper of this conference. The Cooperative Business Management (CBM) Task of DAMA is developing computer-based tools that will render system-wide information accessible for improved decision making. Three CBM strategies and the associated computer tools being developed to support their implementation are described in this paper. This effort is addressing the second DAMA goal to establish a textile industry electronic marketplace in concert with the Connectivity and Infrastructure Task of DAMA. As the CBM tools mature, they will be commercialized through the DAMA Education, Outreach and Commercialization Task of DAMA to achieve the third and final DAMA goal.
The Aging Aircraft NDI Validation Center (AANC) was established by the Federal Aviation Administration Technical Center (FAATC) at Sandia National Laboratories in August of 1991. The goal of the AANC is to provide independent validation of technologies intended to enhance the structural inspection of aging commuter and transport aircraft. The deliverables from the AANC`s validation activities are assessments of the reliability of existing and emerging inspection technologies as well as analyses of the cost benefits to be derived from their implementation. This paper describes the methodology developed by the AANC to assess the performance of NDI techniques. In particular, an experiment being developed to evaluate corrosion detection devices will be presented. The experiment uses engineered test specimens, as well as complete aircraft test beds to provide metrics for NDI validation.
Sandia`s Institutional Plan is by necessity a large document. As their missions have grown and diversified over the past decades, the variety of technical and site activities has increased. The programs and activities described here cover an enormous breadth of scientific and technological effort--from the creation of new materials to the development of a Sandia-wide electronic communications system. Today, there are three major themes that greatly influence this work. First, every federally funded institution is being challenged to find ways to become more cost effective, as the US seeks to reduce the deficit and achieve a balanced federal spending plan. Sandia is evaluating its business and operational processes to reduce the overall costs. Second, in response to the Galvin Task Force`s report ``Alternative Futures for the Department of Energy National Laboratories``, Sandia and the Department of Energy are working jointly to reduce the burden of administrative and compliance activities in order to devote more of the total effort to their principal research and development missions. Third, they are reevaluating the match between their missions and the programs they will emphasize in the future. They must demonstrate that Sandia`s roles--in national security, energy security, environmental integrity, and national scientific and technology agenda support--fit their special capabilities and skills and thus ensure their place in these missions for the longer planning horizon. The following areas are covered here: Sandia`s mission; laboratory directives; programmatic activities; technology partnerships and commercialization; Sandia`s resources; and protecting resources and the community.
A new approach to product development is described that integrates various unit operations into a unified ``knowledge-base``. This knowledge-base is easily accessible to all members of the design team due to the advent of high performance and networking capabilities of today`s desktop computers. This permits rapid optimization of the product`s material, shape, and manufacturing processes that satisfy the customer`s performance requirements while maximizing economic return for the manufacturer.
The Department of Energy (DOE) has been developing a planning process for mixed low-level waste (MLLW) disposal in conjunction with the affected states for over two years and has screened the potential disposal sites from 49 to 15. A radiological performance evaluation was conducted on these fifteen sites to further identify their strengths and weaknesses for disposal of MLLW. Technical analyses are on-going. The disposal evaluation process has sufficiently satisfied the affected states` concerns to the point that disposal has not been a major issue in the consent order process for site treatment plans. Additionally, a large amount of technical and institutional information on several DOE sites has been summarized. The relative technical capabilities of the remaining fifteen sites have been demonstrated, and the benefits of waste form and disposal facility performance have been quantified. However, the final disposal configuration has not yet been determined. Additionally, the MLLW disposal planning efforts will need to integrate more closely with the low-level waste disposal activities before a final MLLW disposal configuration can be determined. Recent Environmental Protection Agency efforts related to the definition of hazardous wastes may also affect the process.
The growth of polycrystalline and amorphous aluminum-oxygen alloy films using electron-beam evaporation of Al in the presence of an O{sub 2} electron-cyclotron-resonance (ECR) plasma was investigated for film compositions varying from 40% Al (Al{sub 2}O{sub 3}) to near 100% Al (AlO{sub x}). Processing parameters such as deposition temperature and ion energy were varied to study their effects on surface texture and film microstructure. The Al-rich films (AlO{sub x}) contain polycrystalline fcc Al grains with finely dispersed second-phase particles of {gamma}-Al{sub 2}O{sub 3} (1-2 nm in size). The surface roughness of these films was measured by atomic force microscopy and found to increase with sample bias and deposition temperature. Stoichiometric Al{sub 2}O{sub 3} films grown at 100{degrees}C and 400{degrees}C without an applied bias were amorphous, while an applied bias of -140 V formed a nanocrystalline {gamma}-Al{sub 2}O{sub 3} film at 400{degrees}C. The surface roughness of the Al{sub 2}O{sub 3} increased with temperature while ion irradiation produced a smoother surface.
Sandia National Laboratories` (SNL) Technical Library is now responsible for providing citation verification management support for all references cited in technical reports issued by the Nuclear Waste Management (NWM) Program. This paper dancing how this process is managed for the Yucca Mountain Site Characterization (YWP), Waste Isolation Pilot Plant (WIPP), Idaho National Engineering Laboratory (INEL), and Greater Confinement Disposal (GCD) projects. Since technical reports are the main product of these projects, emphasis is placed on meeting the constantly evolving needs of these customers in a timely and cost-effective manner.
Various applications are currently motivating interest in the transmission of very high laser intensities through optical fibers. As intensities within a fiber are increased, however, laser breakdown or laser-induced fiber damage will eventually occur and interrupt fiber transmission. For a number of years we have been studying these effects during the transmission of Q-switched, Nd/YAG laser pulses through step-index, multimode, fused-silica fiber. We have found that fiber transmission is often limited by a plasma-forming breakdown occurring at the fiber entrance face. This breakdown results in subtle surface modifications that can leave the surface more resistant to further breakdown or damage events. Catastrophic fiber damage can also occur as a result of a number of different mechanisms, with damage appearing at fiber end faces, within the initial ``entry`` segment of the fiber path, and at other internal sites due to effects related to the particular fiber routing. An overview of these past observations is presented, and issues requiring further study are identified.
A long standing problem in low-temperature plasma discharge physics is to understand in detail the mutual interaction of real exposed surfaces (electrodes) with the reactive plasma environment. In particular, one wishes to discern the influence of these surfaces on the plasma parameters given their contributions from secondary electrons and ions. This paper briefly reviews the known surface interaction processes as well as currently available diagnostics to study the interface between plasmas and surfaces. Next comes a discussion describing the application of plasma-modulated electroreflectance to this research and some potential experimental techniques.
Low-energy deposition of Al(O) alloys from an electron cyclotron resonance (ECR) plasma offers a scaleable method for the synthesis of thick, high-strength Al layers. This work compares alloy layers formed by an ECR-0{sub 2} plasma in conjunction with Al evaporation to 0-implanted Al (ion energies 25-200 keV); and it examines the effects of volume fraction of A1{sub 2}0{sub 3} phase and deposition temperature on the yield stress of the material. TEM showed the Al(O) alloys contain a dense dispersion of small {gamma}-Al{sub 2}0{sub 3} precipitates ({approximately}l nm) in a fine-grain (10-100 nm) fcc Al matrix when deposited at a temperature of {approximately}100C, similar to the microstructure for gigapascal-strength 0-implanted Al. Nanoindentation gave hardnesses for ECR films from 1.1 to 3.2 GPa, and finite-element modeling gave yield stresses up to 1.3 {plus_minus} 0.2 GPa with an elastic modulus of 66 GPa {plus_minus} 6 GPa (similar to pure bulk Al). The yield stress of a polycrystalline pure Al layer was only 0.19 {plus_minus} 0.02 GPa, which was increased to 0.87 {plus_minus} 0.15 GPa by implantation with 5 at. % 0.
Several effects of seismic activity on the release of radionuclides from a potential repository at Yucca Mountain are quantified. Future seismic events are predicted using data from the seismic hazard analysis conducted for the Exploratory Studies Facility (ESF). Phenomenological models are developed, including rockfall (thermal-mechanical and seismic) in unbackfilled emplacement drifts, container damage caused by fault displacement within the repository, and flow-path chance caused by changes in strain. Using the composite-porosity flow model (relatively large-scale, regular percolation), seismic events show little effect on total-system releases; using the weeps flow model (episodic pulses of flow in locally saturated fractures), container damage and flow-path changes cause over an order of magnitude increase in releases. In separate calculations using, more realistic representations of faulting, water-table rise caused by seismically induced changes in strain are seen to be higher than previously estimated by others, but not sufficient to reach a potential repository.
Development of a vapor generator for consistently producing accurate amounts of vapor from low vapor pressure explosive materials is a pressing need within the explosives detection community. Of particular importance for reproducibility and widespread acceptance of results is the correlation of such a vapor generator to a National Institute of Standards and Technology (NIST) mass standard. This paper describes an explosives vapor generator recently developed at Varian in which a solid explosive sample in a precision bore glass tube is put in an oven at constant temperature, and vapor diff-using from the top of the tube is entrained in a carrier gas flow. The rate of vapor output is thus dependent on both the equilibrium vapor pressure of the solid at oven temperature and the rate of diffusion up the length of the tube. Correlation to a NIST mass standard is achieved by periodic weighing of the sample tube on a microbalance. We report results obtained with the explosives TNT and RDX. Results for TNT show that the mass output rate is constant over hundreds of hours of continuous use, with outputs of {approximately} 10--2000 pg/sec for oven temperatures in the range of 60--120{degrees}C. Both the mass loss experiments and calibration with an ion mobility spectrometer (IMS) give a TNT mass output value of 85 pg/sec at 79{degrees}C, and this result is supported by transport theory calculations. Mass loss curves for RDX are also linear with time, and show the expected exponential increase of mass output with oven temperature.
This paper presents an implemented algorithm that automatically designs fixtures and assembly pallets to hold three-dimensional parts. The designed fixtures rigidly constrain and locate the part, obey task constraints, are robust to part shape variations, are easy to load, and are economical to produce. The algorithm is guaranteed to find the global optimum solution that satisfies these and other pragmatic conditions. We present the results of the algorithm applied to several practical manufacturing problems. For these complex problems the algorithm typically returns initial high-quality fixture designs in less than two minutes, and identifies th global optimum design in just over an hour.
Multichip modules (MCMs) containing power components need a substrate with excellent heat spreading capability both to avoid hot spots and to move dissipated heat toward the system heat sinks. Polycrystalline diamond is an excellent MCM heat spreading substrate but remains several orders of magnitude too expensive and somewhat more difficult to process than conventional mother-board materials. Today`s power MCMs concentrate on moderately priced silicon wafers and aluminum nitride ceramic with their improved thermal conductivity and good thermal expansion match to power semiconductor components, in comparison to traditional alumina and printed wiring board materials. However, even silicon and AlN substrates are challenged by designers` thermal needs. We report on the fabrication of micro-heat pipes embedded in silicon MCM substrates (5{times}5 cm) by the use of micromachined capillary wick structures and hermetic micro-cavities. This passive microstructure results in more than a 5 times improvement in heat spreading capability of the silicon MCM substrate over a large range of power densities and operating temperatures as compared with silicon alone. Thus diamond-like cooling is possible at silicon prices.
This paper describes a study in which HTML style guides were characterized, compared to established HCI style guides, and evaluated against findings from HCI reviews of web paces and applications. Findings showed little consistency among the 21 HTML style guides assessed, with 75% of recommendations appearing in only one style guide. While there was some overlap, only 20% of HTML relevant recommendations from established style guides were found in HTML style guides. HTML style guides emphasized common look and feel, information display, and navigation issues with little mention of many issues prominent in established style guides such as help, message boxes and data entry. This difference is reinforced by other results showing that HTML style guides addressed concerns of web information content pages with much greater success than web-based applications. It is concluded that while the WWW represents a unique HCI environment, development of HTML style guides has been less rigorous, with issues associated with web-based applications largely ignored.
Piezoelectric actuators provide high frequency, force, and stiffness capabilities along with reasonable Stroke limits, all of which can be used to increase performance levels in precision manufacturing systems. This paper describes two examples of embedding piezoelectric actuators in structural components for vibration control. One example involves suppressing the self excited chatter phenomenon in the metal cutting process of a milling machine and the other involves damping vibrations induced by rigid body stepping of a photolithography platen. Finite element modeling and analyses are essential for locating and sizing the actuators and permit further simulation studies of the response of the dynamic system. Experimental results are given for embedding piezoelectric actuators in a cantilevered bar configuration, which was used as a surrogate machine tool structure. These results are incorporated into a previously developed milling process simulation and the effect of the control on the cutting process stability diagram is quantified. Experimental results are also given for embedding three piezoelectric actuators in a surrogate photolithography platen to suppress vibrations. These results demonstrate the potential benefit that can be realized by applying advances from the field of adaptive structures to problems in precision manufacturing.
Electron cyclotron resonance (ECR) etching of GaN in Cl{sub 2}/H{sub 2}/Ar, C1{sub 2}/SF{sub 6}/Ar, BCl{sub 3}/H{sub 2}/Ar and BCl{sub 3}/SF{sub 6}/Ar plasmas is reported as a function of percent H{sub 2} and SF{sub 6}. GaN etch rates were found to be 2 to 3 times greater in Cl{sub 2}/H{sub 2}/Ar discharges than in BCl{sub 3}/H{sub 2}/Ar discharges independent of the H{sub 2} concentration. In both discharges, the etch rates decreased as the H{sub 2} concentration increased above 10%. When SF{sub 6} was substituted for H{sub 2}, the GaN etch rates in BCl{sub 3}-based plasmas were greater than those for the Cl{sub 2}-based discharges as the SF{sub 6} concentration increased. GaN etch rates were greater in Cl{sub 2}/H{sub 2}/Ar discharges as compared to Cl{sub 2}SF{sub 6}/Ar discharges whereas the opposite trend was observed for BCl{sub 3}-based discharges. Variations in surface morphology and near-surface stoichiometry due to plasma chemistries were also investigated using atomic force microscopy and Auger spectroscopy, respectively.
A ``debris-less`` laser-plasma source (LPS) of extreme-UV radiation has been developed by Kubiak, et al. This is a huge step forward for the extreme-UV lithography program (EUVL) because it will extend the life of the collecting mirrors that face the source. This source has a 300-{mu}m diameter (D source) which is larger than the earlier, {approximately}75-{mu}m diameter plasma balls created on metal targets. The larger source size requires that the Etendu of the system must also be larger if the source radiation is to be used efficiently. A family of 4-mirror, scanning, ring-field lithography cameras has been designed that can be efficiently coupled to a ``debris-less`` LPS. The most promising design has a 0.085-numerical aperture (NA{sub camera}) for printing {approx} 100-nm features. At the image plane it has 13 nm of distortion and a 98% Strehl ratio across its 7-mm wide ring-field ({Delta}r).
VICTORIA-92 is a mechanistic computer code for analyzing fission product behavior within the reactor coolant system (RCS) during a severe reactor accident. It provides detailed predictions of the release of radionuclides and nonradioactive materials from the core and transport of these materials within the RCS. The modeling accounts for the chemical and aerosol processes that affect radionuclide behavior. Coupling of detailed chemistry and aerosol packages is a unique feature of VICTORIA; it allows exploration of phenomena involving deposition, revaporization, and re-entrainment that cannot be resolved with other codes. The purpose of this work is to determine the attenuation of fission products in the RCS and on the secondary side of the steam generator in an accident initiated by a steam generator tube rupture (SGTR). As a class, bypass sequences have been identified in NUREG-1150 as being risk dominant for the Surry and Sequoyah pressurized water reactor (PWR) plants.
When assembling a product, humans, robots, and other automation employ a variety of tools to manipulate, attach, and test parts and subassemblies. This paper proposes a framework lo represent and reason about geometric accessibility constraints for a wide variety of assembly tools. Central to the framework is a use volume encoding a minimum space that must be free in an assembly state to apply a given tool, and placement constraints on where that volume must be placed relative to the parts on which the tool acts. Determining whether a tool can be applied in a given assembly state is an instance of the FINDPLACE problem. In addition, we present more efficient methods lo integrate the framework into assembly planning. For tools that are applied either before or after their target parts are mated, one method preprocesses a single tool application for all possible states of assembly of a product. For tools applied after their target parts are mated, a complementary method guarantees polynomial-time assembly planning. We describe experiments with an initial implementation of the framework and a library of seven tools.
In a virtual environment with multiple participants, it is necessary that the user`s actions be replicated by synthetic human forms. Whole body digitizers would be the most realistic solution for capturing the individual participant`s human form, however the best of the digitizers available are not interactive and are therefore not suitable for real-time interaction. Usually, a limited number of sensors are used as constraints on the synthetic human form. Inverse kinematics algorithms are applied to satisfy these sensor constraints. These algorithms result in slower interaction because of their iterative nature, especially when there are a large number of participants. To support real-time interaction in a virtual environment, there is a need to generate closed for solutions and fast searching algorithms. In this paper, a new closed form solution for the arms (and legs) is developed using two magnetic sensors. In developing this solution, we use the biomechanical relationship between the lower arm and the upper arm to provide an analytical, non-iterative solution, We have also outlined a solution for the whole human body by using up to ten magnetic sensors to break the human skeleton into smaller kinematic chains. In developing our algorithms, we use the knowledge of natural body postures to generate faster solutions for real-time interaction.
The underlying report for this paper evaluates options for using depleted uranium as shielding materials for transport systems for disposal of vitrified high-level waste (VHLW). In addition, economic analyses are presented to compare costs associated with these options to costs, associated with existing and proposed storage, transport, and diposal capabilities. A more detailed evaluation is provided elsewhere. (Yoshimura et al. 1995.)
This paper discusses the core damage frequency (CDF) insights gained by analyzing the results of the Individual Plant Examinations (IPES) for two groups of plants: boiling water reactor (BWR) 3/4 plants with Reactor Core Isolation Cooling systems, and Westinghouse 4-loop plants. Wide variability was observed for the plant CDFs and for the CDFs of the contributing accident classes. On average, transients-with loss of injection, station blackout sequences, and transients with loss of decay heat removal are important contributors for the BWR 3/4 plants, while transients, station blackout sequences, and loss-of-coolant accidents are important for the Westinghouse 4-loop plants. The key factors that contribute to the variability in the results are discussed. The results are often driven by plant-specific design and operational characteristics, but differences in modeling approaches are also important for some accident classes.
Local public opposition to federal bureaucratic decisions has resulted in public agencies rethinking the role of stakeholders in decision making. Efforts to include stakeholders directly in the decision-making process are on the increase. Unfortunately, many attempts to involve members of the public in decisions involving complex technical issues have failed. A key problem has been defining a meaningful role for the public in the process of arriving at a technical decision. This paper describes a successful effort by Sandia National Laboratories (SNL) in New Mexico to involve stakeholders in an important technical decision associated with its Environmental Restoration (ER) Project. The decision was where to locate a Corrective Action Management Unit (CAMU), a facility intended to consolidate and store wastes generated from the cleanup of hazardous waste sites. A formal priority setting process known as the Laboratory Integration Prioritization System (LIPS) was adapted to provide an approach for involving the public. Although rarely applied to stakeholder participation, the LIPS process proved surprisingly effective. It produced a consensus over a selected site and enhanced public trust and understanding of Project activities.
System Certification is a regulatory concept which is intended to expand the scope of radioactive material transport regulations by allowing alternative means for proving compliance with the requisite standards of safety set out in transport regulations. In practice it may allow more stringent requirements in one aspect of the regulations to be substituted for less stringent application in other areas so long as the safety standard provided by regulation is preserved. The concept is widely perceived as the imposition of operational controls in exchange for relaxation of packaging standards, but that is only one possibility in the spectrum of potential actions under a System Certification provision in IAEA or national regulations.
Sandia has made considerable progress in the past year on the MELCOR code for integrated severe nuclear reactor accident analysis. Actinities for the past year are presented.
The design and analysis of a high brightness electron beam experiment under construction at Sandia National Laboratory is presented. The beam energy is 12 MeV, the current 35-40 kA, the rms radius 0.5 mm, and the pulse duration FWHM 40 ns. The accelerator is SABRE a pulsed inductive voltage adder, and the electron source is a magnetically immersed foilless diode. This experiment has as its goal to stretch the technology to the edge and produce the highest possible electron current in a submillimeter radius beam.
The quality assurance requirements that apply to the effort to achieve safe transportation, storage, and disposal of high-level nuclear waste specify that ``design control`` be applied to design activities. That effort also involves extensive scientific investigation activities to, among other things, develop information that may be used in engineering design activities. Individuals who are charged with the implementation of such quality assurance requirements have come to a variety of conclusions about whether there is any firm linkage between design control and the conduct of scientific investigations. This paper contends that there is a reasonable and necessary linkage between ``design control`` and scientific activities, though not a connection that has traditionally been made and not one addressed in the QA standards for radioactive waste management programs.
The III-V nitride-containing semiconductors InN, GaN, and AIN and their ternary alloys are the focus of extensive research for application to visible light emitters and as the basis for high temperature electronics. Recent advances in ion implantation doping of GaN and studies of the effect of rapid thermal annealing up to 1100{degrees}C are making new device structures possible. Both p- and n-type implantation doping of GaN has been achieved using Mg co-implanted with P for p-type and Si-implantation for n-type. Electrical activation was achieved by rapid thermal anneals in excess of 1000{degrees}C. Atomic force microscopy studies of the surface of GaN after a series of anneals from 750 to 1100{degrees}C shows that the surface morphology gets smoother following anneals in Ar or N{sub 2}. The photoluminescence of the annealed samples also shows enhanced bandedge emission for both annealing ambients. For the deep level emission near 2.2 eV, the sample annealed in N{sub 2} shows slightly reduced emission while the sample annealed in Ar shows increased emission. These annealing results suggest a combination of defect interactions occur during the high temperature processing.
Inclusion of renewable energy sources in national and international energy strategies is a key component of a viable global energy future. The global energy balance is going to shift radically in the near future brought about by significant increases in population in China and India, and increases in the energy intensity of developing countries. To better understand the consequences of such global shifts in energy requirements and to develop appropriate energy strategies to respond to these shifts, we need to look at the factors driving choices among supply options by geopolitical consumers and the impact these factors can have on the future energy mix.
High-speed optoelectronic modulators are becoming increasingly important in microwave applications. These devices are necessarily electrically large and hence require velocity matching of the microwave signal to the light. A design methodology for velocity matched electrodes on doped semiconductor devices will be presented. As an example of a successful device design, experimental results on a >10 bandwidth high-efficiency (>15{degrees}/V/mm) Mach Zehnder interferometer will be presented.
Articles in this issue include ``Molten salt corrosion testing,`` ``Pulsed ion beams for thermal surface treatment: Improved corrosion, wear, and hardness properties at low cost,`` ``Unmasking hidden armaments: Superconducting gravity sensor could find underground weapons, bunkers,`` ``Charbroiled burgers, heterocyclic amines, and cancer: Molecular modeling identifies dangerous mutagens,`` ``Revolutionary airbag offers increased safety options,`` ``EcoSys{sup TM}: an expert system for `Green Design` ``, ``Sandia, salt, and oil: Labs` diagnostics and analysis help maintain vital US oil reserve,`` and ``Automated fixture design speeds development for prototypes and production``.
Drilling is ubiquitous in oil, gas, geothermal, minerals, water well, and mining industries. Drilling and well completion account for 25% to 50% of the cost of producing power from geothermal energy. Reduced drilling costs will reduce the cost of electricity produced from geothermal resources. Undoubtedly, there are concepts for advanced drilling systems that have yet to be studied. However, the breadth and depth of previous efforts in this area almost guarantee that any new efforts will at least initially build on an idea or a variation of an idea that has already been investigated. Therefore, a review of previous efforts, coupled with a characterization of viable advanced drilling systems and the current state of technology as it applies to those systems, provide the basis for this study.
In order to understand and evaluate materials for use in Li ion rechargeable battery electrodes, we have modeled the crystal structures of various Mn oxide and Li Mn oxide compounds. We have modeled the MnO{sub 2} polymorphs and several spinels with intermediate compositions based on the amount of Li inserted into the tetrahedral site. 3-D representations of the structures provide a basis for identifying site occupancies, coordinations, Mn valence, order-disorder, and potentially new dopants for enhanced cathode behavior. XRD simulations of the crystal structures provide good agreement with observed patterns for synthesized samples. Ionic modeling of these materials consists of an energy minimization approach using Coulombic, repulsive, and van der Waals interactions. Modeling using electronic polarizabilities (shell model) allows a systematic analysis of changes in lattice energy, cell volume, and the relative stability of doped structures using ions such as Al, Ti, Ni, and Co.
Several novel polysilanes synthesized by the free-radical hydrosilation of oligomeric polyphenylsilane or poly(p-tert- butylphenylsilane) were examined for lithographic behavior. This recently developed route into substituted polysilanes has allowed for the rational design of a variety of polysilanes with a typical chemical properties such as alcohol and aqueous base solubility. Many of the polysilane resists made could be developed in aqueous sodium carbonate and bicarbonate solutions. These materials represent environmentally friendly polysilane resists in both their synthesis and processing.
Results from a chamber study to characterize emissions from combustion of selected pure energetic materials are presented in this paper. The study was carried out as a part of a comprehensive air pathways risk assessment for a propellant and explosive manufacturing facility that engages in open burning methods for manufacturing waste disposal. Materials selected for emissions characterization in this study included both aluminized and non-aluminized composite propellant, a double base propellant and a plastic bonded explosive. Combustion tests in a specialized chamber revealed very low emissions for gaseous products of incomplete combustion such as carbon monoxide and nitrogen oxides. Analysis of gaseous and aerosol emission products for a pre-selected target analyte list that included both volatile and semi-volatile organics revealed either low or non-detectable emissions for the four energetic types tested. Hydrogen chloride was detected as a major emission product from propellants containing ammonium perchlorate. Results from this work reveal that about one-half of the chlorine in the original material is released as hydrogen chloride. Based on earlier work, the balance of the chlorine emissions is expected to be in the form of chlorine gas.
Analysis of processes used for the production of single crystal turbine components reveals significant shortcomings. Inadequate consideration has been made of the fact the system is cooling dominated and that the amount of cooling tends to increase as the emissive cooling area expands during the process. Experimental evidence suggests that during processing, this increased cooling causes the solidification interface to move away from the baffle and become curved. The motion of the interface results in a decrease in the solidification gradient. The combination of these actions can result in variations in PDAS (primary dendrite arm spacing), grain misalignment and the production of defects. It is shown that despite this tendency, microstructural stabilization may be achieved through the use of the heat of fusion as an internal process heat source.
We present calculations of the specific contact resistance for metals to GaN. The calculations include a correct determination of the Fermi level taking into account the effect of the degenerate doping levels, required in creating tunneling ohmic contacts. Using a recently reported improved WKB approximation suitable in representing the depletion width at the metal-semiconductor interface, and a two band k-p model for the effective masses, specific contact resistance was determined as a function of doping concentration. The specific contact resistance was calculated using the best data available for barrier heights, effective masses and dielectric coefficients for GaN. Because the barrier height at the metal-semiconductor interface has a very large effect on the contact resistance and the available data is sketchy or uncertain, the effect of varying the barrier height on the calculated specific contact resistance was investigated. Further, since the III-V nitrides are being considered for high temperature device applications, the specific contact resistance was also determined as a function of temperature.
Lost circulation is a persistent problem in geothermal drilling and often accounts for a significant fraction of the cost of drilling a typical geothermal well. The US Department of Energy sponsors work at Sandia National Laboratories to develop technology for reducing lost circulation costs. This paper describes a downhole tool that has been developed at Sandia for improving the effectiveness and reducing the cost of cementing operations used to treat lost circulation zones. This tool, known as the drillable straddle packer, is a low-cost, disposable assembly used for isolating a loss zone and directing the flow of cement into the zone. This paper describes the tool concept, hardware design, deployment procedure, laboratory testing, and technical issues addressed during the development process.
Variation of model size as determined by grid density is studied for both model refinement and damage detection. In model refinement 3 it is found that a large model with a fine grid is preferable in order to achieve a reasonable correlation between the experimental response and the finite element model. A smaller model falls victim to the inaccuracies of the finite element method. As the grid become increasing finer, the FE method approaches an accurate representation. In damage detection the FE method is only a starting point. The model is refined with a matrix method which doesn`t retain the FE approximation, therefore a smaller model that captures most of the dynamics of the structure can be used and is preferable.
This paper presents a high bandwidth fiber-optic communication system intended for post accident recovery of weapons. The system provides bi-directional multichannel, and multi-media communications. Two smaller systems that were developed as direct spin-offs of the larger system are also briefly discussed.
To model the shock-induced behavior of porous or damaged energetic materials, a nonequilibrium mixture theory has been developed and incorporated into the shock physics code, CTH. Foundation for this multiphase model is based on a continuum mixture formulation given by Baer and Nunziato. In this nonequilibrium approach, multiple thermodynamic and mechanics fields are resolved including the effects of material relative motion, rate-dependent compaction, drag and heat transfer interphase effects and multiple-step combustion. Benchmark calculations are presented which simulate low-velocity piston impact on a propellant porous bed and experimentally-measured wave features are well replicated with this model. This mixture model introduces micromechanical models for the initiation and growth of reactive multicomponent flow which are key features to describe shock initiation and self-accelerated deflagration-to-detonation combustion behavior. To complement one-dimensional simulation, two dimensional numerical simulations are presented which indicate wave curvature effects due to the loss of wall confinement.
This contribution presents some lessons learned in the development of cooperation and knowledge transfer across the numerous interfaces involved in managing a corporate research laboratory.
This contribution addresses requirements for ATM signaling channel authentication. Signaling channel authentication is an ATM security service that binds an ATM signaling message to its source. By creating this binding, the message recipient, and even a third party, can confidently verify that the message originated from its claimed source. This provides a useful mechanism to mitigate a number of threats. For example, a denial of service attack which attempts to tear-down an active connection by surreptitiously injecting RELEASE or DROP PARTY messages could be easily thwarted when authenticity assurances are in place for the signaling channel. Signaling channel authentication could also be used to provide the required auditing information for accurate billing which is impervious to repudiation. Finally, depending on the signaling channel authentication mechanism, end-to-end integrity of the message (or at least part of it) can be provided. None of these capabilities exist in the current specifications.
Crystal lattices are infinite periodic graphs that occur naturally in a variety of geometries and which are of fundamental importance in polymer science. Discrete models of protein folding use crystal lattices to define the space of protein conformations. Because various crystal lattices provide discretizations of the same physical phenomenon, it is reasonable to expect that there will exist ``invariants`` across lattices that define fundamental properties of protein folding process; an invariant defines a property that transcends particular lattice formulations. This paper identifies two classes of invariants, defined in terms of sublattices that are related to the design of algorithms for the structure prediction problem. The first class of invariants is, used to define a master approximation algorithm for which provable performance guarantees exist. This algorithm can be applied to generalizations of the hydrophobic-hydrophilic model that have lattices other than the cubic lattice, including most of the crystal lattices commonly used in protein folding lattice models. The second class of invariants applies to a related lattice model. Using these invariants, we show that for this model the structure prediction problem is intractable across a variety of three-dimensional lattices. It`` turns out that these two classes of invariants are respectively sublattices of the two- and three-dimensional square lattice. As the square lattices are the standard lattices used in empirical protein folding` studies, our results provide a rigorous confirmation of the ability of these lattices to provide insight into biological phenomenon. Our results are the first in the literature that identify algorithmic paradigms for the protein structure prediction problem which transcend particular lattice formulations.
Approximately 13% by volume of the US Department of Energy (DOE) current backlog of radioactive waste is characterized as high-level waste. Transportation of these wastes requires that the waste package have adequate shielding against gamma radiation. This project investigates the radiation shielding performance of titanium and depleted uranium, which have been proposed for use as gamma shielding materials in DOE transportation packages, by experimentally determining their buildup factors. Buildup factors are important in shield heating and radiation damage calculations. A point-isotropic-source type of buildup factor is the most useful for application in the point-kernal approach utilized in many simple shielding codes. The point-kernal method provides reasonable results for cases in which the shield is made of one solid material and the source can be approximated as one homogeneous material. The point-kernal method has been incorporated into a large number of shielding codes treating three-dimensional geometry using buildup factor data in some form. Buildup factors vary with a number of parameters such as the distance of penetration through the attenuating medium; the geometric configuration of the attenuating medium, source and detector position; the composition of the medium; the detector response function; and the energy and direction of emission of the source photons, ideally taken to be monoenergetic and isotropic.
It is likely that the ongoing process to produce the 1996 version of the IAEA Regulation for the Safe Transport of Radioactive Materials, IAEA Safety Series 6(SS 6) will result in a more stringent package qualification standard for air transport of large quantities of radioactive materials (RAM) than is included in the 1990 version. During the process to define the scope of the new requirements there was extensive discussion of their impact on, and application to, fissile material package qualification criteria. Since fissile materials are shipped in a variety of packaging ranging from exempt to Type B, each packaging of each type must be evaluated for its ability to maintain subcriticality both alone and in arrays and in both damaged and undamaged condition. In the 1990 version of SS 6 "damaged" means the condition of a package after it had undergone the "tests for demonstrating the ability to withstand accident conditions in transport," i.e., Type B qualification tests. These tests conditions are typical of severe accidents in surface modes but are less severe than air mode qualification test environments to be applied to Type C packages. As a result, questions arose about the need for a corresponding change in the 1996 SS 6 to define "damaged" to include the Type C test regime for criticality evaluations of fissile packages in air transport.
Intense, pulsed ion beams were used to melt and rapidly resolidify Types 316F, 316L and sensitized 304 stainless steel surfaces to eliminate the negative effects of microstructural heterogeneity on localized corrosion resistance. Anodic polarization curves determined for 316F and 316L showed that passive current densities were reduced and pitting potentials were increased due to ion beam treatment. Type 304 samples sensitized at 600°C for 100 h showed no evidence of grain boundary attack when surfaces were ion beam treated. Equivalent ion beam treatments were conducted with a 6061-T6 aluminum alloy. Electrochemical impedance experiments conducted with this alloy exposed to an aerated chloride solution showed that the onset of pitting was delayed compared to untreated control samples.
Inorganic polycrystalline hydrotalcite, Li2[Al2(OH)6]2·CO3·3H2O, coatings can be formed on aluminum and aluminum alloys by exposure to alkaline lithium carbonate solutions. This process is conducted using methods similar to traditional chromate conversion coating procedures, but does not use or produce toxic chemicals. The coating provides anodic protection and delays the onset of pitting during anodic polarization. Cathodic reactions are also inhibited which may also contribute to corrosion protection. Recent studies have shown that corrosion resistance can be increased by sealing hydrotalcite coated surfaces to transition metal salt solutions including Ce(NO3)3, KMnO4 and Li2MoO4. Results from these studies are also reported.
The Department of Energy's (DOE) non-nuclear facilities generally require only a qualitative accident analysis to assess facility risks in accordance with DOE Order 5481.1B, Safety Analysis and Review System [DOE, 1986]. Achieving a meaningful qualitative assessment of risk necessarily requires the use of suitable non-numerical assessment criteria. Typically, the methods and criteria for assigning facility specific accident scenarios to the qualitative severity and likelihood classification system in the DOE order requires significant judgement in many applications. Systematic methods for more consistently assigning the total accident scenario frequency and associated consequences are required to substantiate and enhance future risk ranking between various activities at Sandia National Laboratories (SNL). Currently, Sandia National Laboratories' Risk Management and National Environmental Policy Act (NEPA) department has initiated a project to develop improved criteria for performing qualitative risk assessments in accordance with the DOE order requirements. Products of this effort are an improved set of qualitative descriptions that permit: (1) definition of the severity for both technical and programmatic consequences that may result from a variety of accident scenarios and, (2) qualitative representation of the likelihood of occurrence. These sets of descriptions are intended to provide, in a qualitative manner, definitions that can be compared with the DOE criteria for assessing facility risks.
Water determination in semiconductor process gases is desirable in order to extend the life of gas delivery systems and improve wafer yields. We review our work in applying Fourier transform infrared spectroscopy to this problem, where a 10 ppb detection limit has been demonstrated for water in N2, HCl, and HBr. The potential for optical determination of other contaminants in these gases is discussed. Also, alternative optical spectroscopic approaches are briefly described. Finally, we discuss methods for dealing with interference arising from water in the instrument beam path, yet outside the sample cell.
Liquid properties are measured from the changes they induce in the resonant frequency and damping of thickness-shear mode quartz resonators. A smooth-surfaced resonator viscously entrains the contacting fluid and responds to the density-viscosity product. Separation of density and viscosity is accomplished using two devices: one with a smooth surface and one with a corrugated surface that traps fluid. By observing the difference in stored and dissipated energies in the contacting fluid, its non-Newtonian characteristics can also be determined.
American Society of Mechanical Engineers, Pressure Vessels and Piping Division (Publication) PVP
Spray, S.D.; Cooper, J.A.
The use of passive safety concepts to achieve very high levels of assured safety is described. Some background on safety implementations and safety assessment methodology are reviewed, the salient features of passive safety implementations are demonstrated, and some applications for which passive safety is particularly appropriate are suggested. Included are requirements on components and processes, and design principles. Critical agents (humans, stress, equipment, and timing) are some of the pertinent factors considered.
This paper reviews the evolution of polymer electrolytes from the conventional PEO-LiX salt complexes to the more conducting polyphosphazene and copolymers, gelled electrolytes etc. It also reviews the various chemical approaches including modifying PEO to synthesizing complicated polymer architecture. In addition, it discusses the effect of various lithium salts on the conductivity of PEO-based polymers. Charge/discharge and cycle life data of polymer cells containing oxide and chalcogenide cathodes and lithium (Li) anode will be reviewed. Finally, future research directions to improve the electrolyte properties will be presented.
Conference Proceedings - Lasers and Electro-Optics Society Annual Meeting-LEOS
Lear, K.L.
Structure based on aluminum-oxide layers have led to dramatic improvements in VCSELs such as power conversion efficiencies in excess of 50% and threshold currents below 10μA. The low index, insulating aluminum-oxide, formed by selective wet thermal oxidation of AlGaAs, serves as an effective index guide as well as a current injection aperture. This paper presents data on devices with either two aligned apertures above and below the active region or with a single effective aperture above the active region leading to slope efficiencies of up to 1W/A.
Proceedings of SPIE - The International Society for Optical Engineering
Eaton, W.P.; Smith, J.H.
A surface micromachined pressure sensor array has been designed and fabricated. The sensors are based upon deformable, silicon nitride diaphragms with polysilicon piezoresistors. Absolute pressure is detected by virtue of reference pressure cavities underneath the diaphragms. For this type of sensor, design tradeoffs must be made among allowable diaphragm deflection, diaphragm size, and desirable pressure ranges. Several fabrication issues were observed and addressed. Offset voltage, sensitivity, and nonlinearity of 100 μm diameter sensors were measured.
The effect of solvent addition on the phase separation, mechanical properties and thermal stability of silica/siloxane composite materials prepared by in situ reinforcement was examined. The addition of a solvent enhances the miscibility of the reinforcement precursor, a partial hydrolyzate of tetraethoxysilane (TEOS-PH), with the polydimethylsiloxane (PDMS) polymer. As a result, the phase separation at the micron level, termed the large-scale structure, diminished in size. This decrease in particle size resulting from the addition of moderate amounts of solvent was accompanied by an improvement in the mechanical properties. However, solvent addition in the excess of 50 weight percent led to a decrease in mechanical properties even though the large-scale structure continued to diminish in size. Small Angle X-Ray Scattering (SAXS) was used to examine the angstrom level or small-scale structure. This small-scale structure was only affected by the presence of solvent, not the amount. The silica/siloxane composite materials showed the same thermal transition temperatures as the original PDMS material.
The preparation of light emitting diodes employing a new class of materials, 5,10-dihetera-5,10-dihydro-indeno[3,2b]indenes, as hole transport agents is described. These materials have been found to be more resistant to degradation by singlet oxygen than a poly(p-phenylene vinylene) (PPV) derivative.
Extensions of the German LIGA process have brought about fabrication capability suitable for cost effective production of precision engineered components. The process attributes allow fabrication of mechanical components which are not capable of being made via conventional subtractive machining methods. Two process improvements have been responsible for this extended capability which involve the areas of thick photoresist application and planarization via precision lapping. Application of low-stress x-ray photoresist has been achieved using room temperature solvent bonding of a preformed photoresist sheet. Precision diamond lapping and polishing has provided a flexible process for the planarization of a wide variety of electroplated metals in the presence of photoresist. Exposure results from the 2.5 GeV National Synchrotron Light Source storage ring at Brookhaven National Laboratory have shown that structural heights of several millimeter and above are possible. The process capabilities are also well suited for microactuator fabrication. Linear and rotational magnetic microactuators have been constructed which use coil winding technology with LIGA fabricated coil forms. Actuator output forces of 1 milliNewton have been obtained with power dissipation on the order of milliWatts. A rotational microdynamometer system which is capable of measuring torque-speed data is also discussed.
Plasma processes for etching and desmear of electronic components and printed wiring boards (PWB) are difficult to predict and control. Non-uniformity of most plasma processes and sensitivity to environmental changes make it difficult to maintain process stability from day to day. To assure plasma process performance, weight loss coupons or post-plasma destructive testing must be used. The problem with these techniques is that they are not real-time methods and do not allow for immediate diagnosis and process correction. These tests often require scrapping some fraction of a batch to insure the integrity of the rest. Since these tests verify a successful cycle with post-plasma diagnostics, poor test results often determine that a batch is substandard and the resulting parts unusable. These tests are a costly part of the overall fabrication cost. A more efficient method of testing would allow for constant monitoring of plasma conditions and process control. Process anomalies should be detected and corrected before the parts being treated are damaged. Real time monitoring would allow for instantaneous corrections. Multiple site monitoring would allow for process mapping within one system or simultaneous monitoring of multiple systems. Optical emission spectroscopy conducted external to the plasma apparatus would allow for this sort of multifunctional analysis without perturbing the glow discharge. In this paper, optical emission spectroscopy for non-intrusive, in situ process control will be explored along with applications of this technique towards process control, failure analysis and endpoint determination.
To verify the excitonic nature of the light-emitting state in PPV, fluorescence intensities and decay lifetimes were investigated as a function of excitation intensity. The results agree with the behavior predicted by the molecular exciton model. In particular, exciton-exciton annihilation causes the fluorescence intensity to saturate and the fluorescence lifetime to shorten at high exciton densities. In addition, the exciton annihilation, and thus diffusion, coefficients are found to be relatively large, even at low temperatures, indicating that exciton migration is important in PPV. These results indicate that the fluorescent (photoluminescent) state in PPV is excitonic in nature. The results argue against the band model where high mobility at reduced temperatures is not expected because the light-emitting species, neutral bipolarons, are associated with large lattice distortions.
Diametral compression strength distributions and the compaction behavior and of irregular shape 150-200 μm ceramic granules and uniform-size 210 μm glass spheres were measured to determine how granule strength variability relates to compaction behavior of granular assemblies. High variability in strength, represented by low Weibull modulus values (m<3) was observed for ceramic granules having a distribution of sizes and shapes, and for uniform-size glass spheres. Compaction pressure data were also analyzed using a Weibull distribution function, and the results were very similar to those obtained from the diametral compression strength tests for the same material. This similarity suggests that it may be possible to model granule compaction using a weakest link theory, whereby an assemblage of granules is viewed as the links of a chain, and failure of the weakest granule (i.e., the weakest link) leads to rearrangement and compaction. Additionally, with the use of Weibull statistics, it appears to be possible to infer the variability in strength of individual granules from a simple pressure compaction test, circumventing the tedious task of testing individual granules.
In ceramic manufacturing processes such as dry-pressing, correlations between applied compacting pressure and resultant powder compact density are essential for defining reliable process conditions for ceramic components. Pressure-density diagrams have been developed as a tool for both process control and for understanding the compaction behavior of different powders. These types of diagrams, however, pertain only to the average properties of a powder compact and do not address a significant issue in powder compaction processes: the formation of density gradients within the compact. Continuum-based mechanics models of varying complexity have addressed the influence of frictional forces acting at the powder-die wall interface which dissipate the applied pressure throughout the compact. Resulting pressure distribution models are then typically coupled with empirical functions relating pressure and density to obtain a green density distribution in the compact. All of these models predict similar trends; however, none predict the distribution with sufficient accuracy to be considered as a design tool for industrial applications.
Because the components of a multiphase flow often exhibit different electrical properties, a variety of probes have been developed to study such flows by measuring impedance in the region of interest. Researchers are now using electric fields to reconstruct the impedance distribution within a measurement volume via Electrical Impedance Tomography (EIT). EIT systems employ voltage and current measurements on the boundary of a domain to create a representation of the impedance distribution within the domain. The development of the Sandia EIT system (S-EIT) is reviewed. The construction of the projection acquisition system is discussed and two specific EIT inversion algorithms are detailed. The first reconstruction algorithm employs boundary element methods, and the second utilizes finite elements. The benefits and limitations of EIT systems are also discussed. Preliminary results are provided.
A flexible, modular manufacturing process for integrating micromechanical and microelectronic devices has been developed. This process embeds the micromechanical devices in an anisotropically etched trench below the surface of the wafer. Prior to microelectronic device fabrication, this trench is refilled with oxide, chemical-mechanically polished, and sealed with a nitride cap in order to embed the micromechanical devices below the surface of the planarized wafer. The feasibility of this technique in a manufacturing environment has been demonstrated by combining a variety of embedded micromechanical structures with a 2 μm CMOS process on 6 inch wafers. A yield of 78% has been achieved on the first devices manufactured using this technique.
New characterization and computational techniques have been developed to evaluate and simulate binder burnout from pressed powder compacts. Using engineering data and a control volume finite element method (CVFEM) thermal model, a nominally one dimensional (1-D) furnace has been designed to test, refine, and validate computer models that stimulate binder burnout assuming a 1-D thermal gradient across the ceramic body during heating. Experimentally, 1-D radial heat flow was achieved using a rod-shaped heater that directly heats the inside surface of a stack of ceramic annuli surrounded by thermal insulation. The computational modeling effort focused on producing a macroscopic model for binder burnout based on continuum approaches to heat and mass conservation for porous media. Two increasingly complex models have been developed that predict the temperature and mass of a porous powder compact as a function of time during binder burnout. The more complex model also predicts the pressure within a powder compact during binder burnout. Model predictions are in reasonably good agreement with experimental data on binder burnout from a 57-65% relative density pressed powder compact of a 94 wt% alumina body containing approx. 3 wt% binder. In conjunction with the detailed experimental data from the prototype binder burnout furnace, the models have also proven useful for conducting parametric studies to elucidate critical material property data required to support model development.
We are exploring the use of functionalized block copolymers for bonding copper to epoxy in printed wiring boards. Our program involves four key elements: i) synthesis of suitable functionalized block copolymers; ii) characterization of the conformation of the copolymers at the relevant interfaces by neutron reflectivity; iii) spectroscopic measurements of chemical bonding, and iv) measurement of the mechanical properties of the interfaces. The copolymers are synthesized by living, ring-opening metathesis polymerization. This relatively new technique allows great flexibility for synthesis of functionalized block copolymers in that the initiators are relatively insensitive to a wide range of functional groups. Significant adhesion enhancement has been observed in lap shear tests.
The pressure-compaction response of a spray-dried, 94% alumina powder containing several percent of a polymeric binder was investigated as a function of die diameter and compact aspect ratio. The results show that the die fill density decreases markedly with decreasing die diameter and aspect ratio, while the final green density (at 120 MPa) decreases only slightly under the same conditions. These results suggest that the ratio of the initial compact dimensions to the size of the granules may be much more important than previously considered.
Sulfuric acid hydrogen peroxide mixtures (SPM) are commonly used in the semiconductor industry to remove organic contaminants from wafer surfaces. This viscous solution is very difficult to rinse off water surfaces. Various rinsing conditions were tested and the resulting residual acid left on the water surface was measured. Particle growth resulting from incomplete rinse is correlated with the amount of sulfur on the wafer surface measured by Time of Flight Secondary Ion Mass Spectroscopy (TOF-SIMS). The amount of sulfur on the wafer structure after the rinse step is strongly affected by the wafer film type and contact angle prior to the SPM clean.
Intercalation anodes of graphite or disordered carbon in rechargeable Li-ion batteries (based on aprotic organic solvents) develop a passivating film during the first intercalation of Li{sup +}. The formation of this film reduces the cycling efficiency and results in excessive consumption of Li{sup +}. The exact nature of this film is not well defined, although there are many similarities in properties to the films that form on Li anodes under similar cycling conditions. In this study we report on characterization studies of films formed during galvanostatic cycling of disordered carbons derived from polymethylacryolintrile (PMAN) in a 1M LiPF{sub 6} solution in ethylene carbonateldimethyl carbonate solution (1:1 by vol.). Complementary tests were also conducted with glass carbon, where intercalation cannot occur. Complex-impedance spectroscopy was the primary measurement technique, supplemented by cyclic voltammetry.
This paper demonstrates a methodology for predicting the service lifetime of wind turbine blades using the high-cycle fatigue data base for typical U.S. blade materials developed by Mandell, et al. (1995). The first step in the analysis is to normalize the data base (composed primarily of data obtained from specialized, relatively small coupons) with fatigue data from typical industrial laminates to obtain a Goodman Diagram that is suitable for analyzing wind turbine blades. The LIFE2 fatigue analysis code for wind turbines is then used for the fatigue analysis of a typical turbine blade with a known load spectrum. In the analysis, a linear damage model, Miner`s Rule, is used to demonstrate the prediction of the service lifetime for a typical wind turbine blade under assumed operating strain ranges and stress concentration factors. In contrast to typical European data, the asymmetry in this data base predicts failures under typical loads to be compressive.
We have investigated whether an in-situ hydrogen or ammonia rf-plasma treatment prior to a PECVD-nitride deposition would promote bulk defect passivation independently of surface effects. We also studied whether the predeposition of a thin silicon-nitride protective layer vbefore performing the plasma treatment would serve to minimize surface damage. We found that for the limited set of deposition conditions in of cells processed using the used five different deposition strategies and compared the resulting cell performance with that investigated so far, the direct deposition of PECVD-nitride produces the best cells on String Ribbon silicon wafers to date, with efficiencies up to 14.5%. Hydrogen and ammonia plasma pretreatments without a protective nitride layer resulted in better bulk passivation, but damaged surfaces. Pretreatments after deposition of the protective layer produced the best surface passivation, but were not effective in passivating the bulk.
Researchers at Plasma Processes Inc. have produced a Functional Gradient Material (FGM) through advanced vacuum plasma spray processing for high heat flux applications. Outlined in this paper are the manufacturing methods used to develop a four component functional gradient material of copper, tungsten, boron, and boron nitride. The FGM was formed with continuous gradients and integral cooling channels eliminating bondlines and providing direct heat transfer from the high temperature exposed surface to a cooling medium. Metallurgical and x-ray diffraction analyses of the materials formed through innovative VPS (vacuum plasma spray) processing are also presented. Applications for this functional gradient structural material range from fusion reactor plasma facing components to missile nose cones to boilers.
This paper investigates the use of artificial neural networks (ANNs) to identify damage in mechanical systems. Two probabilistic neural networks (PNNs) are developed and used to judge whether or not damage has occurred in a specific mechanical system, based on experimental measurements. The first PNN is a classical type that casts Bayesian decision analysis into an ANN framework, it uses exemplars measured from the undamaged and damaged system to establish whether system response measurements of unknown origin come from the former class (undamaged) or the latter class (damaged). The second PNN establishes the character of the undamaged system in terms of a kernel density estimator of measures of system response; when presented with system response measures of unknown origin, it makes a probabilistic judgment whether or not the data come from the undamaged population. The physical system used to carry out the experiments is an aerospace system component, and the environment used to excite the system is a stationary random vibration. The results of damage identification experiments are presented along with conclusions rating the effectiveness of the approaches.
We present a software environment integrating analysis and test based models to support optimal modal test design through a Virtual Environment for Test Optimization (VETO). The VETO assists analysis and test engineers in maximizing the value of each modal test. It is particularly advantageous for structural dynamics model reconciliation applications. The VETO enables an engineer to interact with a finite element model of a test object to optimally place sensors and exciters and to investigate the selection of-data acquisition parameters needed to conduct a complete modal survey. Additionally, the user can evaluate the use of different types of instrumentation such as filters, amplifiers and transducers for which models are available in the VETO. The dynamic response of most of the virtual instruments (including the device under test) are modeled in the state space domain. Design of modal excitation levels and appropriate test instrumentation are facilitated by the VETO`s ability to simulate such features as unmeasured external inputs, A/D quantization effects, and electronic noise. Measures of the quality of the experimental design, including the Modal Assurance Criterion, and the Normal Mode indicator Function are available. The VETO also integrates tools such as Effective Independence and minamac to assist in selection of optimal sensor locations. The software is designed about three distinct modules: (1) a main controller and GUI written in C++, (2) a visualization model, taken from FEAVR, running under AVS, and (3) a state space model and time integration module, built in SIMULINK. These modules are designed to run as separate processes on interconnected machines. MATLAB`s external interface library is used to provide transparent, bidirectional communication between the controlling program and the computational engine where all the time integration is performed.
The experimental data on sorption and solubility of hydrogen isotopes in graphite in a wide ranges of temperature and pressure are reviewed. The Langmuir type adsorption is proposed for the hydrogen -- graphites interaction with taking into account dangling sp{sup 2}{minus}bonds relaxation. Three kinds of traps are proposed: Carbon interstitial loops with the adsorption enthalpy of {minus}4.4 eV/H{sub 2} (Traps l); carbon network edge atoms with the adsorption enthalpy of {minus}2.3 eV/H{sub 2} (Traps 2): Basal planes adsorption sites with enthalpy of +2.43 eV/H{sub 2} (Traps 3). The sorption capacity of every kind of graphite could be described with its own unique set of traps. The number of potential sites for the ``true solubility`` (Traps 3) we assume as 1E+6 appm, or HC=l, but endothermic character of this solubility leads to negligible amount of inventory in comparison with Traps 1 and Traps 2. The irradiation with neutrons or carbon atoms increases the number of Traps 1 and Traps 2. At damage level of {approximately}1 dpa under room temperature irradiation the number of these traps was increased up to 1500 and 5000 appm respectively. Traps 1 and Traps 2 are stable under high temperature annealing.
Last year the USNRC initiated a program at Sandia National Laboratories to determine the potential impact of smoke on advanced safety-related digitial instrumentation. In recognition of the fact that the reliability of safety-related equipment during or shortly after a fire in a nuclear power plant is more risk significant than long-term effects, we are concentrating on short-term failures. We exposed a multiplexer module board to three different types of smoke to determine whether the smoke would affect its operation. The operation of the multiplexer board was halted by one out of the three smoke exposures. In coordination with Oak Ridge National Laboratory, an experimental digital safety system was also smoke tested. The series of tests showed that smoke can cause potentially serious failures of a safety system. Most of these failures were intermittent and showed that smoke can temporarily interrupt communication between digital systems.
This paper describes the use of backscattered electron Kikuchi patterns (BEKP) for phase identification in the scanning electron microscope (SEM). The origin of BEKP is described followed by a discussion of detectors capable of recording high quality patterns. In this study a new detector based on charge coupled device technology is described. Identification of unknown phases is demonstrated on prepared and as received sample surfaces. Identification through a combination of energy dispersive x-ray spectrometry (EDS) and BEKP of a Laves phase in a weld in an alloy of Fe-Co-Ni-Cr-Nb and the identification of Pb{sub 2}Ru{sub 2}O{sub 6.5} crystals on PZT is demonstrated. Crystallographic phase analysis of micron sized phases in the SEM is a powerful new tool for materials characterization.
The Trajectory Analysis and Optimization System (TAOS) is software that simulates point--mass trajectories for multiple vehicles. It expands upon the capabilities of the Trajectory Simulation and Analysis program (TAP) developed previously at Sandia National Laboratories. TAOS is designed to be a comprehensive analysis tool capable of analyzing nearly any type of three degree-of-freedom, point-mass trajectory. Trajectories are broken into segments, and within each segment, guidance rules provided by the user control how the trajectory is computed. Parametric optimization provides a powerful method for satisfying mission-planning constraints. Althrough TAOS is not interactive, its input and output files have been designed for ease of use. When compared to TAP, the capability to analyze trajectories for more than one vehicle is the primary enhancement, although numerous other small improvements have been made. This report documents the methods used in TAOS as well as the input and output file formats.
Sandia is modifying the PBFA II accelerator into a dual use facility. While maintaining the present ion-beam capability, we are developing a long-pulse, high-current operating mode for magnetically-driven implosions. This option, called PBFA II-Z, will require new water transmission lines, a new insulator stack, and new magnetically-insulated transmission lines (MITLs). Each of the existing 36, coaxial water pulse-forming sections will couple to a 4.5-{Omega}, bi-plate water-transmission line. The water transmission lines then feed a four-level insulator stack. The insulators are expected to operate at a maximum, spatially-averaged electric field of {approximately}l00 kV/cm. The MITL design is based on the successful biconic Saturn design. The four ``disk`` feeds will each have a vacuum impedance of {approximately}2.0 {Omega}. The disk feeds are added in parallel using a double post-hole convolute at a diameter of 15 cm. We predict that the accelerator will deliver 20 MA to a 15-mg z-pinch load in 100 ns, making PBFA II-Z the most powerful z-pinch driver in the world providing a pulsed power and load physics scaling testbed for future 40-80-MA drivers.
A rationale was developed to determine which technologies a space nuclear reactor technology based program pursue based on the fact that budgets would be limited. A preliminary evaluation was conducted to identify key technical issues and to recommend a prioritized set of candidate research projects that could be undertaken as part of the Defense Nuclear Agency (DNA) program in the near term. The recommendations made have not been adopted formally by the DNA`s Topaz International Program process. (TIP), but serve as inputs to the program plannin process.
A set of ``templates`` was developed for modeling waste glass interactions with cement-based and clay-based matrices. The templates consist of a modified thermodynamic database, and input files for the EQ3/6 reaction path code, containing embedded rate models and compositions for waste glass, cement, and several pozzolanic materials. Significant modifications were made in the thermodynamic data for Th, Pb, Ra, Ba, cement phases, and aqueous silica species. It was found that the cement-containing matrices could increase glass corrosion rates by several orders of magnitude (over matrixless or clay matrix systems), but they also offered the lowest overall solubility for Pb, Ra, Th and U. Addition of pozzolans to cement decreased calculated glass corrosion rates by up to a factor of 30. It is shown that with current modeling capabilities, the ``affinity effect`` cannot be trusted to passivate glass if nuclei are available for precipitation of secondary phases that reduce silica activity.
A series of CO{sub 2} laser welds were made at a constant beam irradiance of 6 MW/cm{sup 2} on 304 stainless steel with travel speeds selected to produce welds with varying levels of weld penetration. Using a Seebeck envelope calorimeter, the net heat input to the part was measured for each weld. It was found that the energy transfer efficiencies varied from 0.29 to 0.86, and decreased at high travel speeds where the weld penetration depth was as shallow as 0.13 mm. The decrease in beam absorption with decreasing weld pool depth is consistent with an absorption mechanism that requires multiple internal reflections within the weld pool. Equations have been developed which conn -ct the keyhole cavity dimensions with the energy transfer efficiency, and correlations with the experimental data have determined the keyhole cavity radius to be 0.1 mm for a focused laser beam with a spot radius of 0.059 mm.
Costs associated with designing and fabricating fixtures may be a significant portion of the total costs associated with a manufacturing task. The software tool, HoldFast, designs optimal fixtures that hold a single workpiece, are easily fabricated, provide rigid constraint and deterministic location of the workpiece, are robust to workpiece shape variations, obey all associated task constraints, and are easy to load and unload. We illustrate the capabilities of HoldFast by designing fixtures for several examples. Fixtures are designed and built for finish-machining and drilling of a cast part for prototype fabrication and mass-production fabrication. A pallet fixture is designed for vertical assembly of a personal cassette player. Another pallet fixture is designed and built that will hold either the personal cassette player or a glue gun during assembly.
A number of physics problems can be modeled by a set of N elements which have pair-wise interactions with one another. A direct solution technique requires computational effort which is O(N{sup 2}). Fast multipole methods (FMM) have been widely used in recent years to obtain solutions to these problems requiring a computational effort of only 0 (N lnN) or O (N). In this paper we present an overview of several variations of the fast multipole method along with examples of its use in solving a variety of physical problems.
The crystalline silico-titanates developed by the Department of Chemical Engineering at Texas A&M University, Sandia National Laboratories and UOP exhibits extremely high ion exchange selectivity for removing cesium from aqueous defense wastes. Based on experimental data and structure studies, a competitive ion exchange model was proposed to predict the ion exchange performance in different simulated waste solutions. The predicted distribution coefficients were within 10% of the experimentally determined values.
In late 1994, Sandia National Laboratories in Albuquerque, New Mexico, (SNL/NM), was instructed by the Department of Energy (DOE) Isotope Production and Distribution Program (IPDP) to examine the feasibility of producing medically useful radioisotopes using the Annular Core Research Reactor (ACRR) and the Hot Cell Facility (HCF). Los Alamos National Laboratory (LANL) would be expected to supply the targets to be irradiated in the ACRR. The intent of DOE would be to provide a capability to satisfy the North American health care system demand for {sup 99}Mo, the parent of {sup 99m}Tc, in the event of an interruption in the current Canadian supply. {sup 99m}Tc is used in 70 to 80% of all nuclear medicine procedures in the US. The goal of the SNL/NM study effort is to determine the physical plant capability, infrastructure, and staffing necessary to meet the North American need for {sup 99}Mo and to identify and examine all issues with potential for environmental impact.
This report presents a two-year LDRD research effort into multisensor data fusion. We approached the problem by addressing the available types of data, preprocessing that data, and developing fusion algorithms using that data. The report reflects these three distinct areas. First, the possible data sets for fusion are identified. Second, automated registration techniques for imagery data are analyzed. Third, two fusion techniques are presented. The first fusion algorithm is based on the two-dimensional discrete wavelet transform. Using test images, the wavelet algorithm is compared against intensity modulation and intensity-hue-saturation image fusion algorithms that are available in commercial software. The wavelet approach outperforms the other two fusion techniques by preserving spectral/spatial information more precisely. The wavelet fusion algorithm was also applied to Landsat Thematic Mapper and SPOT panchromatic imagery data. The second algorithm is based on a linear-regression technique. We analyzed the technique using the same Landsat and SPOT data.
This document describes the processes to be used for creating corporate information systems within the scope of the Integrated Information Services (IIS) Center. Issue B describes all phases of the life cycle, with strong emphasis on the interweaving of the Analysis and Design phases. This Issue B supersedes Issue A, which concentrated on the Analysis and Implementation phases within the context of the entire life cycle. Appendix A includes a full set of examples of the deliverables, excerpted from the Network Database. Subsequent issues will further develop these life cycle processes as we move toward enterprise-level management of information assets, including information meta-models and an integrated corporate information model. The phases described here, when combined with a specifications repository, will provide the basis for future reusable components and improve traceability of information system specifications to enterprise business rules.
The RADTRAN 4 computer code, which calculates estimates of accident dose-risk corresponding to specified transportation scenarios, ascribes doses to potentially exposed members of the public. These persons are modeled as not being evacuated from the affected area for 24 hours following a release of radioactive material. Anecdotal evidence has suggested that this value may be unnecessarily conservative; consequently risk estimates are unnecessarily high. An initial survey of recent trucking accidents, reported in newspapers and other periodicals (1988 through 1994), that involved evacuation of the general population in the affected areas was undertaken to establish the actual time required for such evacuations. Accidents involving hazardous materials other than those which are radioactive (e.g., gasoline, insecticides, other chemicals) but also requiring evacuations of nearby residents were included in the survey. However, the resultant set of sufficiently documented trucking incidents yielded rather sparse data [1]. When the probability density distribution of the truck accident data was compared with that resulting from addition of four other (rail and fixed site) incidents, there was no statistically significant difference between them. Therefore, in order to improve the statistical significance of the data set, i.e., maximize the number of pertinent samples, a search for evacuations resulting from all types of accidents was performed. This resulted in many more references; a set of 48 incidents which could be adequately verified was compiled and merged with the original two data sets for a total of 66 evacuation accounts.
This paper presents a nonlocal analysis of the dynamic damage accumulation processes in brittle solids. A nonlocal formulation of a microcrack based continuum damage model is developed and implemented into a transient dynamic finite element computer code. The code is then applied to the study of the damage accumulation process in a concrete plate with a central hole and subjected to the action of a step tensile pulse applied at opposite edges of the plate. Several finite element discretizations are used to examine the mesh size effect. Comparisons between calculated results based on local and nonlocal formulations are made and nonlocal effects are discussed.
Cables have been identified as critical components requiring detailed technical evaluation for extending the lifetime of Light Water Reactors beyond 40 years. This paper highlights some of the DOE-sponsored cable aging studies currently underway at Sandia. These studies are focused on two important issues: the validity of the often-used Arrhenius thermal aging prediction method and methods for predicting lifetimes in combined thermal-radiation environments. Accelerated thermal aging results are presented for three cable jacket and insulation materials, which indicate that hardening of the outside surface has an Arrhenius temperature dependence and correlates well with reductions in ultimate tensile elongation. This suggests that the indentor approach is a promising NDE technique for cable jacket and unjacketed insulation materials installed in thermally-dominated regions of nuclear power plants.
The 1994 Fernald field characterization demonstration program, hosted by Fernald Environmental Management Project, was established to investigate technologies that are applicable to the characterization and remediation of soils contaminated with uranium. An important part of this effort was evaluating field-screening tools potentially capable of acquiring high-resolution information on uranium contamination distribution in surface soils. Further-more, the information needed to be obtained in a cost- and time-efficient manner. Seven advanced field-screening technologies were demonstrated at a uranium-contaminated site at Fernald, located 29 kilometers northwest of Cincinnati, Ohio. The seven technologies tested were: (1) alpha-track detectors, (2) a high-energy beta scintillometer, (3) electret ionization chambers, (4) and (5) two variants of gamma-ray spectrometry, (6) laser ablation-inductively coupled plasma-atomic emission spectroscopy, and (7) long-range alpha detection. The goals of this field demonstration were to evaluate the capabilities of the detectors and to demonstrate their utility within the US Department of Energy`s Environmental Restoration Program. Identical field studies were conducted using four industry-standard characterization tools: (1) a sodium-iodide scintillometer, (2) a low-energy FIDLER scintillometer, (3) a field-portable x-ray fluorescence detector, and (4) standard soil sampling coupled with laboratory analysis. Another important aspect of this program was the application of a cost/risk decision model to guide characterization of the site. This document is a compilation of raw data submitted by the technologies and converted total uranium data from the 1994 Fernald field characterization demonstration.
Prosperity Games are an outgrowth and adaptation of move/countermove and seminar War Games. Prosperity Games are simulations that explore complex issues in a variety of areas including economics, politics, sociology, environment, education and research. These issues can be examined from a variety of perspectives ranging from a global, macroeconomic and geopolitical viewpoint down to the details of customer/supplier/market interactions in specific industries. All Prosperity Games are unique in that both the game format and the player contributions vary from game to game. This report documents the Environmental Prosperity Game conducted under the sponsorship of the Silicon Valley Environmental Partnership. Players were drawn from all stakeholders involved in environmental technologies including small and large companies, government, national laboratories, universities, environmentalists, the legal profession, finance, and the media. The primary objectives of this game were to: investigate strategies for developing a multi-agency (national/state/regional), one-step regulatory approval process for certifying and implementing environmental technologies and evaluating the simulated results; identify the regulatory hurdles and requirements, and the best approaches for surmounting them; identify technical problems and potential resources (environmental consultants, labs, universities) for solving them. The deliberations and recommendations of these players provided valuable insights as to the views of this diverse group of decision makers concerning environmental issues, including the development, licensing, and commercialization of new technologies.
The LRSTF report for Phase I of its evaluation of low-residue soldering was issued in June 1995. This Appendix summarizes the results of follow-on testing performed in Phase II and compares electrical test results for both phases. Deliberate decisions were made by the LRSTF in Phase I to challenge the design guideline limits in MILSTD-275, Printed Wiring for Electronic Equipment The LRSTF considered this approach to produce a ``worst case`` design and provide useful information about the robustness of LR soldering processes. As such, good design practices were sometimes deliberately violated in designing the LRSTF board. This approach created some anomalies for both LR boards and RMA/cleaned controls. Phase II testing verified that problems that affected both RMA/cleaned and LR boards in Phase I were design related.
This report summarizes the technical progress made in the past three years on CRADA No. 1078, Molecular Engineering of Polymer Alloys. The thrust of this CRADA was to start with the basic ideas of PRISM theory and develop it to the point where it could be applied to modeling of polymer alloys. In this program, BIOSYM, Sandia and the University of Illinois worked jointly to develop the theoretical techniques and numerical formalisms necessary to implement the theoretical ideas into commercial software aimed at molecular engineering of polymer alloys. This CRADA focused on developing the techniques required to make the transition from theory to practice. These techniques were then used by BIOSYM to incorporate PRISM theory and other new developments into their commercial software.
Constitutive models describing the deformation of crushed salt are presented in this report. Ten constitutive models with potential to describe the phenomenological and micromechanical processes for crushed salt were selected from a literature search. Three of these ten constitutive models, termed Sjaardema-Krieg, Zeuch, and Spiers models, were adopted as candidate constitutive models. The candidate constitutive models were generalized in a consistent manner to three-dimensional states of stress and modified to include the effects of temperature, grain size, and moisture content. A database including hydrostatic consolidation and shear consolidation tests conducted on Waste Isolation Pilot Plant and southeastern New Mexico salt was used to determine material parameters for the candidate constitutive models. Nonlinear least-squares model fitting to data from the hydrostatic consolidation tests, the shear consolidation tests, and a combination of the shear and hydrostatic tests produces three sets of material parameter values for the candidate models. The change in material parameter values from test group to test group indicates the empirical nature of the models. To evaluate the predictive capability of the candidate models, each parameter value set was used to predict each of the tests in the database. Based on the fitting statistics and the ability of the models to predict the test data, the Spiers model appeared to perform slightly better than the other two candidate models. The work reported here is a first-of-its kind evaluation of constitutive models for reconsolidation of crushed salt. Questions remain to be answered. Deficiencies in models and databases are identified and recommendations for future work are made. 85 refs.
To properly characterize the transport of contaminants from the sediments beneath the Hanford Site into the Columbia River, a suite of In Situ Permeable Flow Sensors was deployed to accurately characterize the hydrologic regime in the banks of the river. The three dimensional flow velocity was recorded on an hourly basis from mid May to mid July, 1994 and for one week in September. The first data collection interval coincided with the seasonal high water level in the river while the second interval reflected conditions during relatively low seasonal river stage. Two flow sensors located approximately 50 feet from the river recorded flow directions which correlated very well with river stage, both on seasonal and diurnal time scales. During time intervals characterized by falling river stage, the flow sensors recorded flow toward the river while flow away from the river was recorded during times of rising river stage. The flow sensor near the river in the Hanford Formation recorded a component of flow oriented vertically downward, probably reflecting the details of the hydrostratigraphy in close proximity to the probe. The flow sensor near the river in the Ringold Formation recorded an upward component of flow which dominated the horizontal components most of the time. The upward flow in the Ringold probably reflects regional groundwater flow into the river. The magnitudes of the flow velocities recorded by the flow sensors were lower than expected, probably as a result of drilling induced disturbance of the hydraulic properties of the sediments around the probes. The probes were installed with resonant sonic drilling which may have compacted the sediments immediately surrounding the probes, thereby reducing the hydraulic conductivity adjacent to the probes and diverting the groundwater flow away from the sensors.
Cavity type receivers are used extensively in concentrating solar thermal energy collecting systems. The Solar Total Energy Project (STEP) in Shenandoah, Georgia is a large scale field test for the collection of solar thermal energy. The STEP experiment consists of a large field array of solar collectors used to supplement the process steam, cooling and other electrical power requirements of an adjacent knitwear manufacturing facility. The purpose of the tests, conducted for this study, was to isolate and quantify the radiative, conductive, and convective components of total heat loss, and to determine the effects of operating temperature, receiver angle, and aperture size on cavity heat loss. An analytical model for radiative heat loss was developed and compared with two other methods used to determine radiative heat loss. A proposed convective heat loss correlation, including effects of aperture size, receiver operating temperature, and receiver angle is presented. The resulting data is a source to evaluate the STEP measurements.
The light ion impurities C, 0 and H have been implanted or diffused into GaN and related compounds and their effect on the electrical properties of these materials measured by Hall, C-V and SIMS as a function of annealing temperatures from 300--11OO{degree}C. While C in as-grown GaN appears to create an acceptor under MOMBE conditions, implanted C shows no measurable activity. Similarly, implanted 0 does not show any shallow donor activity after annealing at {le}700{degree}C, but can create high resistivity regions (10{sup 6} {Omega}/{open_square}) in GaN, AlInN and InGaN for device isolation when annealed at 500--70O{degree}C. Finally, hydrogen is found to passivate shallow donor and acceptor states in GaN, InN. InAlN and InGaN, with dissociation of the neutral complexes at >450{degree}C. The liberated hydrogen does not leave the nitride films until much higher annealing temperatures (>800{degree}C). Typical reactivation energies are {approximately}2.0 eV for impurity-hydrogen complexes.
This document represents a summary of 58 technologies that are being developed by the Department of Energy`s (DOE`s) Office of Science and Technology (OST) to provide site, waste, and process characterization and monitoring solutions to the DOE weapons complex. The information was compiled to provide performance data on OST-developed technologies to scientists and engineers responsible for preparing Remedial Investigation/Feasibility Studies (RI/FSs) and preparing plans and compliance documents for DOE cleanup and waste management programs. The information may also be used to identify opportunities for partnering and commercialization with industry, DOE laboratories, other federal and state agencies, and the academic community. Each technology is featured in a format that provides: (1) a description, (2) technical performance data, (3) applicability, (4) development status, (5) regulatory considerations, (6) potential commercial applications, (7) intellectual property, and (8) points-of-contact. Technologies are categorized into the following areas: (1) Bioremediation Monitoring, (2) Decontamination and Decommissioning, (3) Field Analytical Laboratories, (4) Geophysical and Hydrologic Characterization, (5) Hazardous Inorganic Contaminant Analysis, (6) Hazardous Organic Contaminant Analysis, (7) Mixed Waste, (8) Radioactive Contaminant Analysis, (9) Remote Sensing,(10)Sampling and Drilling, (11) Statistically Guided Sampling, and (12) Tank Waste.
Non-toxic aqueous foams are being developed by Sandia National Laboratories (SNL) for the National Institute of Justice (NIJ) for use in crowd control, cell extractions, and group disturbances in the criminal justice prison systems. The potential for aspiration of aqueous foam during its use and the resulting adverse effects associated with complete immersion in aqueous foam is of major concern to the NIJ when examining the effectiveness and safety of using this technology as a Less-Than-Lethal weapon. This preliminary study was designed to evaluate the maximum quantity of foam that might be aspirated by an individual following total immersion in an SNL-developed aqueous foam. A.T.W. Reed Breathing simulator equipped with a 622 Silverman cam was used to simulate the aspiration of an ammonium laureth sulfate aqueous foam developed by SNL and generated at expansion ratios in the range of 500:1 to 1000:1. Although the natural instinct of an individual immersed in foam is to cover their nose and mouth with a hand or cloth, thus breaking the bubbles and decreasing the potential for aspiration, this study was performed to examine a worst case scenario where mouth breathing only was examined, and no attempt was made to block foam entry into the breathing port. Two breathing rates were examined: one that simulated a sedentary individual with a mean breathing rate of 6.27 breaths/minute, and one that simulated an agitated or heavily breathing individual with a mean breathing rate of 23.7 breaths/minute. The results of this study indicate that, if breathing in aqueous foam without movement, an air pocket forms around the nose and mouth within one minute of immersion.
The finite-volume hybrid-grid (FVHG) technique uses both structured and unstructured grid regions in obtaining a solution to the time-domain Maxwell`s equations. The method is based on explicit time differencing and utilizes rectilinear finite-difference time-domain (FDTD) and nonorthogonal finite-volume time-domain (FVTD). The technique directly couples structured FDTD grids with unstructured FVTD grids without the need for spatial interpolation across grid interfaces. In this paper, the FVHG method is applied to simple planar microelectronic devices. Local tetrahedron grids are used to model portions of the device under study, with the remainder of the problem space being modeled with cubical hexahedral cells. The accuracy of propagating microstrip-guided waves from a low-density hexahedron region through a high-density tetrahedron grid is investigated.
This paper describes an algorithm for determining the optimal placement of a robotic manipulator within a workcell for minimum time coordinated motion. The algorithm uses a simple principle of coordinated motion to estimate the time of a joint interpolated motion. Specifically, the coordinated motion profile is limited by the slowest axis. Two and six degrees of freedom examples are presented. In experimental tests on a FANUC S-800 arm, the optimal placement of the robot can improve the cycle time of a robotic operation by as much as 25%. In high volume processes where the robot motion is currently the limiting factor, this increased throughput can result in substantial cost savings.
This report describes an experimental study that supported the LDRD program ``A General Approach for Analyzing Composite Structures``. The LDRD was a tightly coupled analytical / experimental effort to develop models for predicting post-yield progressive failure in E-glass fabric/polyester composites subjected to a variety of loading conditions. Elastic properties, fracture toughness parameters, and failure responses were measured on flat laminates, rings and tubes to support the development and validation of material and structural models. Test procedures and results are presented for laminates tested in tension, compression, flexure, short beam shear, double cantilever beam Mode I fracture toughness, and end notched flexure Mode II fracture toughness. Structural responses, including failure, of rings loaded in diametral compression and tubes tested in axial compression, are also documented.
In this report, we present a simple and somewhat preliminary numerical model of a sinusoidal lobed injector. The lobed (corrugated) injector is being considered by several investigators as a potentially efficient device to mix fuel and air for combustion purposes. In this configuration, air flows parallel to the troughs and valleys of corrugations which grow in amplitude in the stream-wise direction. These ramped corrugations produce stream-wise vortices which enhance the downstream mixing. For the lobed injector, the corrugations are actually double walled which allows one to inject fuel through the space between them into the flow downstream of the ramp. The simulation model presented herein is based on a vorticity formulation of the Navier-Stokes equations and is solved using an unsteady viscous vortex method. In order to demonstrate the utility of this method we have simulated the three-dimensional cold mixing process for injection of methane gas into air. The vorticity and fuel concentration field downstream of the injector are simulated for two different injector geometries. We observe from these two simulations that variation of the amplitude of the corrugations can be used to achieve considerably different mixing patterns downstream of the injector.
The conditions and occurrence of gas in crude oil stored in Strategic Petroleum Reserve, SPR, caverns is characterized in this report. Many caverns in the SPR show that gas has intruded into the oil from the surrounding salt dome. Historical evidence and the analyses presented here suggest that gas will continue to intrude into many SPR caverns in the future. In considering why only some caverns contain gas, it is concluded that the naturally occurring spatial variability in salt permeability can explain the range of gas content measured in SPR caverns. Further, it is not possible to make a one-to-one correlation between specific geologic phenomena and the occurrence of gas in salt caverns. However, gas is concluded to be petrogenic in origin. Consequently, attempts have been made to associate the occurrence of gas with salt inhomogeneities including anomalies and other structural features. Two scenarios for actual gas intrusion into caverns were investigated for consistency with existing information. These scenarios are gas release during leaching and gas permeation through salt. Of these mechanisms, the greater consistency comes from the belief that gas permeates to caverns through the salt. A review of historical operating data for five Bryan Mound caverns loosely supports the hypothesis that higher operating pressures reduce gas intrusion into caverns. This conclusion supports a permeability intrusion mechanism. Further, it provides justification for operating the caverns near maximum operating pressure to minimize gas intrusion. Historical gas intrusion rates and estimates of future gas intrusion are given for all caverns.
Panitz, J.K.; Hsu, W.L.; Tallant, D.R.; Mcmaster, M.; Fox, C.; Staley, D.
Densifying non-mined diamond powder precursors with diamond produced by chemical vapor infiltration (CVI) is an attractive approach for forming thick diamond deposits that avoids many potential manufacturability problems associated with predominantly chemical vapor deposition (CVD) processes. The authors developed techniques for forming diamond powder precursors and densified these precursors in a hot filament-assisted reactor and a microwave plasma-assisted reactor. Densification conditions were varied following a fractional factorial statistical design. A number of conclusions can be drawn as a result of this study. High density diamond powder green bodies that contain a mixture of particle sizes solidify more readily than more porous diamond powder green bodies with narrow distributions of particle sizes. No composite was completely densified although all of the deposits were densified to some degree. The hot filament-assisted reactor deposited more material below the exterior surface, in the interior of the powder deposits; in contrast, the microwave-assisted reactor tended to deposit a CVD diamond skin over the top of the powder precursors which inhibited vapor phase diamond growth in the interior of the powder deposits. There were subtle variations in diamond quality as a function of the CVI process parameters. Diamond and glassy carbon tended to form at the exterior surface of the composites directly exposed to either the hot filament or the microwave plasma. However, in the interior, e.g. the powder/substrate interface, diamond plus diamond-like-carbon formed. All of the diamond composites produced were grey and relatively opaque because they contained flawed diamond, diamond-like-carbon and glassy carbon. A large amount of flawed and non-diamond material could be removed by post-CVI oxygen heat treatments. Heat treatments in oxygen changed the color of the composites to white.
This paper presents a new algorithm for solving general inequality/equality constrained minimum time problems. The algorithm`s solution time is linear in the number of Runge-Kutta steps and the number of parameters used to discretize the control input history. The method is being applied to a three link redundant robotic arm with torque bounds, joint angle bounds, and a specified tip path. It solves case after case within a graphical user interface in which the user chooses the initial joint angles and the tip path with a mouse. Solve times are from 30 to 120 seconds on a Hewlett Packard workstation. A zero torque history is always used in the initial guess, and the algorithm has never crashed, indicating its robustness. The algorithm solves for a feasible solution for large trajectory execution time t{sub f} and then reduces t{sub f} and then reduces t{sub f} by a small amount and re-solves. The fixed time re- solve uses a new method of finding a near-minimum-2-norm solution to a set of linear equations and inequalities that achieves quadratic convegence to a feasible solution of the full nonlinear problem.
As part of the effort to clean up hazardous waste sites, Sandia National Laboratories in New Mexico (SNL/NM) adopted a novel approach to involving stakeholders in a key decision associated with its Environmental Restoration (ER) Project. The decision was where to locate a Corrective Action Management Unit (CAMU), an area designed to consolidate, store, and treat wastes generated from cleanup activities. The decision-making approach was a variation of a technique known as multiattribute utility analysis (MUA). Although MUA has rarely been undertaken during normal Project activities, it proved to be a surprisingly effective means for involving stakeholders in the decision process, generating consensus over a selected site, and enhancing public trust and understanding of Project activities. Requirements and criteria for selecting CAMU sites are provided by the Environmental Protection Agency`s (EPA`s) CAMU Final Rule (EPA 1993). Recognizing the lack of experience with the Rule and the importance of community understanding and support, the ER Project sought an approach that would allow stakeholders to participate in the site-selection process.
The emergence of several rapid prototyping & manufacturing (RP&M) technologies is having a dramatic impact on investment casting. While the most successful of the rapid prototyping technologies are almost a decade old, relatively recent process advances in their application have produced some remarkable success in utilizing their products as patterns for investment castings. Sandia National Laboratories has been developing highly coupled experimental and computational capabilities to examine the investment casting process with the intention of reducing the amount of time required to manufacture castings, and to increase the quality of the finished product. This presentation will begin with process aspects of RP&M pattern production and handling, shell fabrication, burnout, and casting. The emphasis will be on how the use of Stereolithography (SL) or Selective Laser Sintered (SLS) patterns differs from more traditional wax pattern processes. Aspects of computational simulation to couple design, thermal analysis, and mold filling will be discussed. Integration of these topics is probably the greatest challenge to the use of concurrent engineering principles with investment casting. Sandi has conducted several experiments aimed at calibrating computer codes and providing data for input into these simulations. Studied involving materials as diverse as stainless steel and gold have been conducted to determine liquid metal behavior in molds via real time radiography. The application of these experiments to predictive simulations will be described.
A number of experiments were conducted to determine the economic viability of applying various ultraviolet (UV) oxidation processes to a waste water stream containing approximately 12 mg/L total organic carbon (TOC), predominately ethylene glycol. In all experiments, a test solution was illuminated with either near-UV or a far-UV light alone or in combination with a variety of photocatalysts and oxidants. Based upon the outcomes of this project, both UV/photocatalysis and UV/ozone processes are capable of treating the water sample to below detection capabilities of TOC. However, the processes are fairly energy intensive; the most efficient case tested required 11 kWh per order of magnitude reduction in TOC per 1000 L. If energy consumption rates of 5-10 kWh/1000 L are deemed reasonable, then further investigation is recommended.
A sinkhole measuring 11 m (36 ft) across and 9 m (30 ft) deep was first observed in alluvium overlying the Weeks Island, Louisiana, salt dome in May 1992, but it was about a year old, based on initial surface appearance and subsequent reverse extrapolation of growth rates. A second and much smaller sinkhole was identified in early 1995, nearly three years later. Their position directly over the edges of the SPR oil storage chamber, a former room-and-pillar salt mine, caused apprehension. The association of sinkholes over mines is well established and this occurrence suggested that groundwater influx undoubtedly was causing salt dissolution at shallow depth, and associated collapse of soil at the surface. Leaks of groundwater into other salt mines in Louisiana and elsewhere led to flooding and eventual abandonment (Coates et al., 1981). Consequently, much attention has been and continues to be given to characterizing these sinkholes, and to mitigation. This paper summarizes current engineering geologic concepts, and briefly describes diagnostic and risk mitigation efforts being conducted by the US Department of Energy, operator of the Strategic Petroleum Reserve (Bauer et al., 1994).
BISDN services will involve the integration of high speed data, voice, and video functionality delivered via technology similar to Asynchronous Transfer Mode (ATM) switching and SONET optical transmission systems. Customers of BISDN services may need a variety of data authenticity and privacy assurances, via Asynchronous Transfer Mode (ATM) services Cryptographic methods can be used to assure authenticity and privacy, but are hard to scale for implementation at high speed. The incorporation of these methods into computer networks can severely impact functionality, reliability, and performance. While there are many design issues associated with the serving of public keys for authenticated signaling and for establishment of session cryptovariables, this paper is concerned with the impact of encryption itself on such communications once the signaling and setup have been completed. Network security protections should be carefully matched to the threats against which protection is desired. Even after eliminating unnecessary protections, the remaining customer-required network security protections can impose severe performance penalties. These penalties (further discussed below) usually involve increased communication processing for authentication or encryption, increased error rate, increased communication delay, and decreased reliability/availability. Protection measures involving encryption should be carefully engineered so as to impose the least performance, reliability, and functionality penalties, while achieving the required security protection. To study these trade-offs, a prototype encryptor/decryptor was developed. This effort demonstrated the viability of implementing certain encryption techniques in high speed networks. The research prototype processes ATM cells in a SONET OC-3 payload. This paper describes the functionality, reliability, security, and performance design trade-offs investigated with the prototype.
A summary of multidimensional modeling is presented which describes coupled thermals chemical and mechanical response of reactive and nonreactive materials. This modeling addresses cookoff of energetic material (EM) prior to the onset of ignition. Cookoff, lasting from seconds to days, sensitizes the EM whereupon combustion of confined, degraded material determines the level of violence. Such processes are dynamic, occurring over time scales of millisecond to microsecond, and thus more amenable for shock physics analysis. This work provides preignition state estimates such as the amount of decomposition, morphological changes, and quasistatic stress states for subsequent dynamic analysis. To demonstrate a fully-coupled thermal/chemical/quasistatic mechanical capability, several example simulations have been performed: (1) the one-dimensional time-to-explosion experiments, (2) the Naval Air Weapon Center`s (NAWC) small scale cookoff bomb, (3) a small hot cell experiment and (4) a rigid, highly porous, closed-cell polyurethane foam. Predictions compared adequately to available data. Deficiencies in the model and future directions are discussed.
An overview of the major sensor and actuator projects using the micromachining capabilities of the Microelectronics Development Laboratory at Sandia National Laboratories is presented. Development efforts are underway for a variety of surface micromachined sensors and actuators. A technology that embeds micromechanical devices below the surface of the wafer prior to microelectronics fabrication has also been developed for integrating microelectronics with surface micromachined micromechanical devices.
Electrochemical power sources that utilize zinc electrodes possess many advantages. Zinc is abundantly available, benign, inexpensive, stable over a wide operating temperature range, and has a high oxidation potential. In spite of these advantageous characteristics, rechargeable electrochemical systems based on zinc chemistry have not found widespread use. The major disadvantages of zinc electrodes are that they have limited cycle life due to zinc slumping and zinc electrode shape changes in alkaline solutions resulting from the solubility of zincate (Zn(OH){sub 4}{sup 2-}) in these solutions. As a result, premature cell failure often results due to cell shorting caused by dendritic growth as well as zinc slumping. In this paper we describe the chemical and physical characteristics of electrolyte solutions employing additives, particularly for zinc based electrochemical systems. These electrolytes are prepared using the alkali metal salts of 1,3,5-phenyltrisulfonic acid in combination with potassium hydroxide. The alkali metal salts of the acid possess good thermal stability, good ionic conductivity, and have a wide electrochemical voltage window in aqueous systems. With these electrolyte solutions improved cycle life was achieved in Zn/NiOOH and Zn/AgO. Improved cycle life with this additive is attributed to decreased zincate solubility, resulting in reduced zinc slumping and electrode shape changes. In addition, increased shelf-life and reduced self-discharge were also observed in many alkaline power sources.
The authors report about the shock-compression response of highly porous (55% and 65% dense) mixtures of 4Al + 3SiO{sub 2} powders having shock-induced phase transitions and chemical reactions. Shock recovery experiments were performed using the CETR/Sawaoka plate-impact system (P = 40 to 100 GPa) and the Sandia Momma Bear A Comp B fixture (P = 22 to 45 GPa). The recovered compacts contained the high pressure stishovite phase, products of chemical reaction, as well as unreacted constituents. The reaction products formed included Al{sub 2}O{sub 3} metallic Si (ambient and high pressure phases), SiAl intermetallic, and kyanite (Al{sub 2}SiO{sub 5}). The shock-induced chemical reaction in 4Al + 3SiO{sub 2} powder mixtures, appears to have been accompanied (or assisted) by the formation of stishovite, a high pressure phase of quartz.
Recent research has shown that dilute SC-1 chemistries, when combined with high frequency sonication (megasonics) can be highly effective for particle removal. The mechanism by which the SC-1 chemistry facilitates particle removal remains unclear. Experiments were performed under extremely dilute conditions in order to help elucidate a cleaning mechanism. Results indicate that hydrogen peroxide, under extremely dilute conditions, is not necessary for effective particle removal. The increase in haze commonly attributed to increased surface roughness is not observed when sufficiently dilute ammonium hydroxide (e.g., 1:2700) is used. The role of hydrogen peroxide, when more concentrated chemistries are used, may be simply to mitigate surface etching and roughening, rather than to play an active role in particle removal.
Stand-alone photovoltaic (PV) systems typically depend on battery storage to supply power to the load when there is cloudy weather or no sun. Reliable operation of the load is often dependent on battery performance. This paper presents test procedures for lead-acid batteries which identify initial battery preparation, battery capacity after preparation, charge regulation set-points, and cycle life based on the operational characteristics of PV systems.
Dish/Stirling is a solar thermal electric technology which couples parabolic, point-focusing solar collectors and heat engines which employ the Stirling thermodynamic cycle. Since the late 1970s, the development of Dish/Stirling systems intended for commercial use has been in progress in Germany, Japan, and the US. In the next several years it is expected that one or more commercial systems will enter the market place. This paper provides a general overview of this emerging technology, including: a description of the fundamental principles of operation of Dish/Stirling systems; a presentation of the major components of the systems (concentrator, receiver, engine/alternator, and controls); an overview of the actual systems under development around the world, with a discussion of some of the technical issues and challenges facing the Dish/Stirling developers. A brief discussion is also presented of potential applications for small Dish/Stirling systems in northern Mexico.
Occasionally one may be confronted by a hexahedral or quadrilateral mesh containing doublets, two faces sharing two edges. In this case, no amount of smoothing will produce a mesh with agreeable element quality: in the planar case, one of these two faces will always have an angle of at least 180 degrees between the two edges. The authors describe a robust scheme for refining a hexahedral or quadrilateral mesh to separate such faces, so that any two faces share at most one edge. Note that this also ensures that two hexahedra share at most one face in the three dimensional case. The authors have implemented this algorithm and incorporated it into the CUBIT mesh generation environment developed at Sandia National Laboratories.
The ability to perform effective adaptive analysis has become a critical issue in the area of physical simulation. Of the multiple technologies required to realize a parallel adaptive analysis capability, automatic mesh generation is an enabling technology, filling a critical need in the appropriate discretization of a problem domain. The paving algorithm`s unique ability to generate a function-following quadrilateral grid is a substantial advantage in Sandia`s pursuit of a modified h-method adaptive capability. This characteristic combined with a strong transitioning ability allow the paving algorithm to place elements where an error function indicates more mesh resolution is needed. Although the original paving algorithm is highly serial, a two stage approach has been designed to parallelize the algorithm but also retain the nice qualities of the serial algorithm. The authors approach also allows the subdomain decomposition used by the meshing code to be shared with the finite element physics code, eliminating the need for data transfer across the processors between the analysis and remeshing steps. In addition, the meshed subdomains are adjusted with a dynamic load balancer to improve the original decomposition and maintain load efficiency each time the mesh has been regenerated. This initial parallel implementation assumes an approach of restarting the physics problem from time zero at each interaction, with a refined mesh adapting to the previous iterations objective function. The remeshing tools are being developed to enable real time remeshing and geometry regeneration. Progress on the redesign of the paving algorithm for parallel operation is discussed including extensions allowing adaptive control and geometry regeneration.
Although the frequency dependent conductivity, {sigma}({omega}), of ion-containing glasses displays power law dispersion ({sigma}({omega}) {approx} {omega}{sup n}) that can usually be described by a master curve, several findings have suggested that this scaling fails at low temperatures as indicated by a temperature dependence of the scaling exponent, n. The authors investigate this behavior in the frequency range between 1 Hz and 10{sup 6} Hz for a different materials including alkali metaphosphate glasses and a polymer. They identify two distinct regimes of conductive behavior, {sigma}{sub {vert_bar}} and {sigma}{sub {parallel}}. The first, {sigma}{sub {vert_bar}}, is strongly temperature dependent and appears to obey a master curve representation. The second, {sigma}{sub {parallel}}, exhibits only a weak temperature dependence with a roughly linear frequency dependence. A strong depression of {sigma}{sub {vert_bar}} occurs for the mixed alkali case, but {sigma}{sub {parallel}} is unaffected and occurs at roughly the same location in all the alkali compositions studied. They propose that {sigma}{sub {parallel}} does not arise from cation motion, but rather originates from a second mechanisms likely involving small distortions of the underlying glassy matrix. This assignment of {sigma}{sub {parallel}} is further supported by the roughly universal location of {sigma}{sub {parallel}}, to within an order of magnitude, of a variety of materials, including a polymer electrolyte and a doped crystal. Since {sigma}{sub {vert_bar}}(T) and {sigma}{sub {parallel}}(T {approx} const.) are viewed as separate phenomena, the temperature dependence of the scaling exponent is shown to result merely from a superposition of these two contributions and does not indicate any intrinsic failure of the scaling property of {sigma}{sub {vert_bar}}.
The needs of today`s advanced societies have moved well beyond the requirements for food and shelter, etc., and now are focused on such concerns as international peace and domestic security, affordable health care, the swift and secure transmission of information, the conservation of resources, and a clean environment. Progress in materials science and engineering is impacting each of these concerns. This paper will present some examples of how this is occurring, and then comment on ethical dilemmas that can arise as a consequence of technological advances. The need for engineers to participate more fully in the development of public policies that help resolve such dilemmas, and so promote the benefits of advancing technology to society, will be discussed.
The Web Interface Template System (WITS) is a tool for software developers. WITS is a three-tiered, object-oriented system operating in a Client/Server environment. This tool can be used to create software applications that have a Web browser as the user interface and access a Sybase database. Development, modification, and implementation are greatly simplified because the developer can change and test definitions immediately, without writing or compiling any code. This document explains WITS functionality, the system structure and components of WITS, and how to obtain, install, and use the software system.
In order to provide a strategy for space reactor technology development, the Defense Nuclear Agency (DNA) has authorized a brief review of potential national needs that may be addressed by space reactor systems. a systematic approach was used to explore needs at several levels that are increasingly specific. Level 0 -- general trends and issues; Level 1 -- generic space capabilities to address trends; Level 2 -- requirements to support capabilities; Level 3 -- system types capable of meeting requirements; Level 4 --generic reactor system types; and Level 5 -- specific baseline systems. Using these findings, a strategy was developed to support important space reactor technologies within a limited budget. A preliminary evaluation identified key technical issues and provide a prioritized set of candidate research projects. The evaluation of issues and the recommended research projects are presented in a companion paper.
Electron induced etching of sapphire in the presence of Cs has been studied using a variety of surface analytical techniques. We find that this process occurs on both the (0001) and (1102) orientations of sapphire. Monolayer amounts of Al and sub-oxides of Al are thermally desorbed from the surface at temperatures as low as 1000 K when the surface is irradiated with electrons in the presence of Cs. Etching is highly dependent on Cs coverage with the (0001) and (1102) surfaces requiring 2.0 {times} 10{sup 14} and 3.4 {times} 10{sup 14} atoms/cm{sup 2} to support etching, respectively. Adsorption profiles demonstrate that these coverages correspond to initial saturation of the surface with Cs. Electron damage of the surface in the absence of Cs also produces desorption of Al and sub-oxides of Al indicating a possible mechanism for etching. The impact of etching on the surface is to increase the adsorption capacity on the (0001) surface while decreasing both initial adsorption probability and capacity on the (1102) surface.
Glowka, D.A.; Dennis, T.; Le, Phi; Cohen, J.; Chow, J.
Cooperative research is currently underway among five drill bit companies and Sandia National Laboratories to improve synthetic-diamond drill bits for hard-rock applications. This work, sponsored by the US Department of Energy and individual bit companies, is aimed at improving performance and bit life in harder rock than has previously been possible to drill effectively with synthetic-diamond drill bits. The goal is to extend to harder rocks the economic advantages seen in using synthetic-diamond drill bits in soft and medium rock formations. Four projects are being conducted under this research program. Each project is investigating a different area of synthetic diamond bit technology that builds on the current technology base and market interests of the individual companies involved. These projects include: optimization of the PDC claw cutter; optimization of the Track-Set PDC bit; advanced TSP bit development; and optimization of impregnated-diamond drill bits. This paper describes the progress made in each of these projects to date.
The Sandia National Laboratories (SNL) Safeguards and Seals Evaluation Program is evaluating new fiber optic active seal technologies for use at Department of Energy (DOE) facilities. The goal of the program is to investigate active seal technologies that can monitor secured containers storing special nuclear materials (SNM) within DOE vaults. Specifically investigated were active seal technologies that can be used as tamper-indicating devices to monitor secured containers within vaults while personnel remain outside the vault area. Such a system would allow minimal access into vaults while ensuring container content accountability. The purpose of this report is to discuss tamper-indicating devices that were evaluated for possible DOE use. While previous seal evaluations (Phase I and II) considered overall facility applications, this discussion focuses specifically on their use in vault storage situations. The report will highlight general background information, specifications and requirements, and test procedures. Also discussed are the systems available from four manufacturers: Interactive Technologies, Inc., Fiber SenSys, Inc., Inovonics, Inc., and Valve Security Systems.
This paper describes the techniques used to resolve invalid connectivity created as a natural part of the whisker weaving algorithm. These techniques rely on the detection of {open_quotes}repeated hexes{close_quotes} in the STC data, which indicate face pairs which share two edges. The {open_quotes}repeated hex{close_quotes} case is described in detail, including the resolution technique by which a self-intersecting whisker sheet with two independent face loops are created. The algorithm used to construct the primal of an all-hexahedral mesh (i.e. the actual nodes and hex elements) from the connectivity data contained in the STC is also described. The primal is constructed using a {open_quotes}gift-wrapping{close_quotes} algorithm, where all the mesh edges and hexes containing a particular node are found by traversing between hexes already known to share the node. This algorithm is implemented inside the CUBIT code and is used to generate meshes for several example problems.
A first-principles approach to radiation hardness assurance was described that provides the technical background to the present US and European total-dose radiation hardness assurance test methods for MOS technologies, TM 1019.4 and BS 22900. These test methods could not have been developed otherwise, as their existence depends not on a wealth of empirical comparisons of IC data from ground and space testing, but on a fundamental understanding of MOS defect growth and annealing processes. Rebound testing should become less of a problem for advanced MOS small-signal electronics technologies for systems with total dose requirements below 50--100 krad(SiO{sub 2}) because of trends toward much thinner gate oxides. For older technologies with thicker gate oxides and for power devices, rebound testing is unavoidable without detailed characterization studies to assess the impact of interface traps on devices response in space. The QML approach is promising for future hardened technologies. A sufficient understanding of process effects on radiation hardness has been developed that should be able to reduce testing costs in the future for hardened parts. Finally, it is hoped that the above discussions have demonstrated that the foundation for cost-effective hardness assurance tests is laid with studies of the basic mechanisms of radiation effects. Without a diligent assessment of new radiation effects mechanisms in future technologies, one cannot be assured that the present generation of radiation test standards will continue to apply.
The SANDUS (SANdia Digital Underground System) waveform digitizing system was developed by the instrumentation development division in support of underground nuclear testing and first fielded in the late 70`s. This system has been successfully used for over a decade for the digitization of signals from DC to 10 Mhz. This report is intended to be a broad survey of the fundamental performance characteristics of the system. The data included herein were obtained from a small number of channels under a limited number of configurations and should provide the reader with the general range of performance parameters. As a survey, the laboratory and analytical procedures for the tests have not been detailed.
This report is a literature review on cast tooling with the general focus on AISI H13 tool steel. The review includes processing of both wrought and cast H13 steel along with the accompanying microstructures. Also included is the incorporation of new rapid prototyping technologies, such as Stereolithography and Selective Laser Sintering, into the investment casting of tool steel. The limiting property of using wrought or cast tool steel for die casting is heat checking. Heat checking is addressed in terms of testing procedures, theories regarding the mechanism, and microstructural aspects related to the cracking.
A series of ventilation experiments have been performed to assess the potential retention of diesel exhaust constituents in the North Ramp of the Yucca Mountain Site Characterization Project`s Exploratory Studies Facility (ESF). Measurements were taken to help evaluate the potential impact of retained diesel exhaust constituents on future in-situ experiments and long-term waste isolation. Assessment of the diesel exhaust retention in the ESF North Ramp required the measurement of air velocities, meteorological measurements, quantification of exhaust constituents within the ventilation air stream, multiple gas sample collections, and on-line diesel exhaust measurements. In order to assess variability within specific measurements, the experiment was divided into three separate sampling events. Although somewhat variable from event to event, collected data appear to support pre-test assumptions of high retention rates for exhaust constituents within the tunnel. The results also show that complete air exchange in the ESF does not occur within the estimated 16 to 20 minutes derived from the ventilation flowrate measurements. Because the scope of work for these activities covered only measurement and acquisition of data, no judgment is offered by the author as to the implications of this work. Final analyses and decisions based upon the entire compendium of data associated with this investigation is being undertaken by the Repository and ESF Ventilation Design Groups of the Yucca Mountain Site Characterization Project.
This report provides an overview of the fire safety experiments performed under the sponsorship of the German government in the containment building of the decommissioned pilot nuclear power plant known as HDR. This structure is a highly complex, multi-compartment, multi-level building which has been used as the test bed for a wide range of nuclear power plant operation safety experiments. These experiments have included numerous fire tests. Test fire fuel sources have included gas burners, wood cribs, oil pools, nozzle release oil fires, and cable in cable trays. A wide range of ventilation conditions including full natural ventilation, full forced ventilation, and combined natural and forced ventilation have been evaluated. During most of the tests, the fire products mixed freely with the full containment volume. Macro-scale building circulation patterns which were very sensitive to such factors as ventilation configuration were observed and characterized. Testing also included the evaluation of selective area pressurization schemes as a means of smoke control for emergency access and evacuation stairwells.
Extracting information from unstructured text has become an emphasis in recent years due to the large amount of text now electronically available. This status report describes the findings and work done by the end of the first year of a two-year LDRD. Requirements of the approach included that it model the information in a domain independent way. This means that it would differ from current systems by not relying on previously built domain knowledge and that it would do more than keyword identification. Three areas that are discussed and expected to contribute to a solution include (1) identifying key entities through document level profiling and preprocessing, (2) identifying relationships between entities through sentence level syntax, and (3) combining the first two with semantic knowledge about the terms.
This is our final report on Sandia National Laboratories Laboratory- Directed Research and Development (LDRD) project 3517.070. Its purpose has been to investigate lossless compression of digital waveform and image data, particularly the types of instrumentation data generated and processed at Sandia Labs. The three-year project period ran from October 1992 through September 1995. This report begins with a descriptive overview of data compression, with and without loss, followed by a summary of the activities on the Sandia project, including research at several universities and the development of waveform compression software. Persons who participated in the project are also listed. The next part of the report contains a general discussion of the principles of lossless compression. Two basic compression stages, decorrelation and entropy coding, are described and discussed. An example of seismic data compression is included. Finally, there is a bibliography of published research. Taken together, the published papers contain the details of most of the work and accomplishments on the project. This final report is primarily an overview, without the technical details and results found in the publications listed in the bibliography.
CUERVO is a finite element code that is designed for the solution of multi-dimensional field problems described by a general nonlinear, advection-diffusion equation. The code is also applicable to field problems described by diffusion, Poisson or Laplace equations. The finite element formulation and the associated numerical methods used in CUERVO are outlined here; detailed instructions for use of the code are also presented. Example problems are provided to illustrate the use of the code.
A fuel dispersal model for C-141 transport accidents was developed for the Defense Nuclear Agency`s Fuel Fire Technology Base Program to support Weapon System Safety Assessments. The spectrum of accidents resulting from aircraft impact on a runway was divided into three fuel dispersal regimes: low, intermediate, and high-velocity impact. Sufficient data existed in the accident, crash test, and fuel-filled bomb literature to support development of a qualitative framework for dispersal models, but not quantitative models for all regimes. Therefore, a test series at intermediate scale was conducted to generate data on which to base the model for the high-velocity regime. Tests were conducted over an impact velocity range from 12 m/s to 91 m/s and angles of impact from 22.5{degrees} to 67.5{degrees}. Dependent variables were area covered by dispersed fuel, amount of mass in that area, and location of the area relative to the impact line. Test results showed that no liquid pooling occurred for impact velocities greater than 61 m/s, independent of the angle of impact. Some pooling did occur at lower velocities, but in no test was the liquid-layer thickness greater than 5.25 mm.
As part of the High Consequence System Surety project, this work was undertaken to explore, one approach to conducting a surety theme analysis for a software-driven system. Originally, plans were to develop a theoretical approach to the analysis, and then to validate and refine this process by applying it to the software being developed for the Weight and Leak Check System (WALS), an automated nuclear weapon component handling system. As with the development of the higher level High consequence System surety Process, this work was not completed due to changes in funding levels. This document describes the software analysis process, discusses its application in a software, environment, and outlines next steps that could be taken to further develop and apply the approach to projects.
Passive optical components can be broken down into two main groups: Refractive elements and diffractive elements. With recent advances in manufacturing technologies, diffractive optical elements are becoming increasingly more prevalent in optical systems. It is therefore important to be able to understand and model the behavior of these elements. In this report, we present a thorough analysis of a completely general diffractive optical element (DOE). The main goal of the analysis is to understand the diffraction efficiency and power distribution of the various modes affected by the DOE. This is critical to understanding cross talk and power issues when these elements are used in actual systems. As mentioned, the model is based on a completely general scenario for a DOE. This allows the user to specify the details to model a wide variety of diffractive elements. The analysis is implemented straightforwardly in Mathematica. This report includes the development of the analysis, the Mathematica implementation of the model and several examples using the Mathematical analysis tool. It is intended that this tool be a building block for more specialized analyses.
The possibility of subsurface imaging using SAR technology has generated a considerable amount of interest in recent years. One requirement for the successful development of a subsurface imagin system is an understanding of how the soil affects the signal. In response to a need for an electromagnetic characterization of the soil properties, the Radar/Antenna department has developed a measurement system which determines the soils complex electric permittivity and magnetic permeability at UHF frequencies. The one way loss in dB is also calculated using the measured values. There are many reports of measurements of the electric properties of soil in the literature. However, most of these are primarily concerned with measuring only a real dielectric constant. Because some soils have ferromagnetic constituents it is desirable to measure both the electric and magnetic properties of the soil.
The chemical and radiation stability of polyacrylonitrile (PAN) in the form of beads (B-PAN), similar to the beads of composite absorbers, and one selected composite absorber (ammonium molybdophosphate, the active component in PAN binder [AMP-PAN], a prospective candidate for the treatment of acidic wastes) were studied. Aqueous 1M HNO{sub 3} + 1M NaNO{sub 3}, 1M NaOH + 1M NaNO{sub 3}, and 1M NaOH were chosen as simulants of DOE acidic and alkaline wastes. In addition,radiation stability was determined indistilled water. The chemical stability of B-PAN and AMP-PAN beads was tested for a period up to one month of contact with the solution at ambient temperature. The radiation stability of the beads was checked in a radiation dose range 10{sup 3}--10{sup 6} Gy (10{sup 5}--10{sup 8} rads). In acidic solutions the stability of PAN binder was proved not to be limited by either chemical or radiation decomposition. PAN binder may thus be used for preparing composite absorbers for treatment of acid wastes from DOE facilities. The same conclusion is valid for alkaline solutions with pH up to 13. In highly alkaline solutions (concentration of NAOH higher than I M) and in the presence of NaNO{sub 3}, the stability of the tested polyacrylonitrile polymer was sufficient for applications not extending over 10 days. Cross-linking of the polymer caused by ionizing radiation was found to have a positive influence on chemical stability. This effect enables a longer period of applicability of PAN-based composite absorbers. Because of the high sorption rate achievable with PAN-based absorbers, the stability achieved is sufficient for most applications in the DOE complex. The chemical stability of binding polymer may also be further improved by testing another, more suitable type of polymer from the broad family of polyacrylonitrile polymers.
We study the evolution of layer morphology during the early stages of metal chemical vapor deposition (CVD) onto Si(100) via pyrolysis of Fe(CO){sub 5} below 250{degrees}C. Scanning tunneling microscopy (STM) shows that nuclei formation is limited by precursor dissociation which occurs on terraces, not at step sites. Also, the average size of clusters formed during CVD is larger than for Fe growth by evaporation (a random deposition process). Based on STM data and Monte Carlo simulations, we conclude that the CVD-growth morphology is affected by preferential dissociation of Fe(CO){sub 5} molecules at existing Fe clusters -- an autocatalytic effect. We demonstrate that nucleation kinetics can be used to control formation of metal nanostructures on chemically tailored surfaces. Reactive sites on Si (001) are first passivated by hydrogen. H atoms are locally removed by electron stimulated desorption using electrons emitted from the STM tip. Subsequent pyrolysis of Fe(CO){sub 5} leads to selective nucleation and growth of Fe films in the areas where H has been removed.
The computer program LEHGC is a Hybrid Lagrangian-Eulerian Finite-Element Model of HydroGeo-Chemical (LEHGC) Transport Through Saturated-Unsaturated Media. LEHGC iteratively solves two-dimensional transport and geochemical equilibrium equations and is a descendant of HYDROGEOCHEM, a strictly Eulerian finite-element reactive transport code. The hybrid Lagrangian-Eulerian scheme improves on the Eulerian scheme by allowing larger time steps to be used in the advection-dominant transport calculations. This causes less numerical dispersion and alleviates the problem of calculated negative concentrations at sharp concentration fronts. The code also is more computationally efficient than the strictly Eulerian version. LEHGC is designed for generic application to reactive transport problems associated with contaminant transport in subsurface media. Input to the program includes the geometry of the system, the spatial distribution of finite elements and nodes, the properties of the media, the potential chemical reactions, and the initial and boundary conditions. Output includes the spatial distribution of chemical element concentrations as a function of time and space and the chemical speciation at user-specified nodes. LEHGC Version 1.1 is a modification of LEHGC Version 1.0. The modification includes: (1) devising a tracking algorithm with the computational effort proportional to N where N is the number of computational grid nodes rather than N{sup 2} as in LEHGC Version 1.0, (2) including multiple adsorbing sites and multiple ion-exchange sites, (3) using four preconditioned conjugate gradient methods for the solution of matrix equations, and (4) providing a model for some features of solute transport by colloids.
Microelectronic cathode emitter technology being developed at Sandia for supplying continuous low current for flat panel displays appears to be a promising technology for providing high currents when operated in a pulsed, higher voltage mode. If currents in excess of one amp per square centimeter could be produced for tens of microseconds at several kilohertz repetition rate, important applications in such as large volume food or waste sterilization in situ detection, and high power microwave production could be achieved. A testbed was built to perform the experiments. The desired current densities have been demonstrated using small emitter arrays.
Chloride ion contamination at parts per billion concentrations plaques electrochemists studying barrier anodic aluminum oxide film growth and anodic aluminum oxide capacitor manufacturers. Chloride ion contamination slows film growth and reduces film quality. We have demonstrated that synthetic hydrocalcite substantially reduces the detrimental effects of chloride ion contamination in an aqueous electrolyte commonly used to grow barrier anodic aluminum oxide. We have determined that problems arise if precautions are not taken when using synthetic hydrocalcite as a chloride-ion getter in an aqueous electrolyte. Synthetic hydrocalcite is somewhat hydrophobic. If this powder is added directly to an aqueous electrolyte, some powder disperses; some floats to the top of the bath and forms scum that locally impedes anodic film formation. Commercially available powder contains a wide range of particle sizes including submicrometer-sized particles that can escape through filters into the electrolyte and cause processing problems. These problems can be over come if (1) the getter is placed in filter bags, (2) a piece of filter paper is used to skim trace amounts of getter floating on the top of the bath, (3) dummy runs are performed to scavenge chloride-ion loaded getter micelles dispersed in the bath, and (4) substrates are rinsed with a strong stream of deionized water to remove trace amounts of powder after anodization.
Sandia National Laboratories, sponsored by the US Department of Energy`s Office of Energy Management, conducts the photovoltaic balance-of-system program. Under this program, Sandia supports the Department of Defense Strategic Environmental Research Development Plan, SERDP, which is advancing the use of photovoltaics in operational DoD facilities. This report details the acceptance testing of the first of these photovoltaic hybrid systems: the Superior Valley photovoltaic-diesel hybrid system. This is the first of several photovoltaic installations for the Department of Defense. The system hardware tested at Sandia included an inverter, maximum power trackers, and a system controller.
This report lists publications and presentations that are related to inertial confinement fusion and were authored or coauthored by Sandians in the Pulsed Power Sciences Center from 1989 through 1993. The 661 publications and presentations are categorized into the following general topics: (1) reviews, (2) ion sources, (3) ion diodes, (4) plasma opening switches, (5) ion beam transport, (6) targets and deposition physics, (7) advanced driver and pulsed power technology development, (8) diagnostics, and (9) code development. Research in these areas is arranged by topic in chronological order, with the early efforts under each topic presented first. The work is also categorized alphabetically by first author. A list of acronyms, abbreviations, and definitions of use in understanding light ion inertial confinement fusion research is also included.
Recent data collections with the Sandia VHF-UHF synthetic-aperture radar have yielded surprising results; trees appear brighter in the images than expected! In an effort to understand this phenomenon, various small trees have been measured on the Sandia folded compact range with the inverse-synthetic-aperture imaging system. A compilation of these measurements is contained in this report.
Apodaca, T.; Berman, M.; Griego, C.; Jansma, R.; Leatherwood, M.; Lovato, L.; Sanchez, A.
In September, 1994, Sandia`s Diversity Leadership and Education Outreach Center arid the Corporate Diversity Team commissioned a Diversity Action Team (DAT-Phase II) to address the area of team- work. The goal of this DAT was to identify ways to capitalize on the diversity of people to enhance team success at Sandia. Given a six- month lifetime and funding levels of 12 hours per person per month, we chose to accomplish our goal by gathering and analyzing data on the performance and diversity of Sandia teams and publishing this report of our findings. The work presented herein builds on earlier work of this team.
Sealing methods and materials currently used in salt and potash industries were surveyed to determine if systems analogous to the shaft seal design proposed for the Waste Isolation Pilot Plant (WIPP) exist. Emphasis was first given to concrete and then expanded to include other materials. Representative case studies could provide useful design, construction, and performance information for development of the WIPP shaft seal system design. This report contains a summary of engineering and construction details of various sealing methods used by mining industries for bulkheads and shaft liners. Industrial experience, as determined from site visits and literature reviews, provides few examples of bulkheads built in salt and potash mines for control of water. Sealing experiences representing site-specific conditions often have little engineering design to back up the methods employed and even less quantitative evaluation of seal performance. Cases examined include successes and failures, and both contribute to a database of experiences. Mass salt-saturated concrete placement under ground was accomplished under several varied conditions. Information derived from this database has been used to assess the performance of concrete as a seal material. Concrete appears to be a robust material with successes in several case studies. 42 refs.
This report presents the results of instrumentation measurements and observations made during construction of the North Ramp Starter Tunnel (NRST) of the Exploratory Studies Facility (ESF). The information in this report was developed as part of the Design Verification Study, Section 8.3.1.15.1.8 of the Yucca Mountain Site Characterization Plan (DOE 1988). The ESF is being constructed by the US Department of Energy (DOE) to evaluate the feasibility of locating a potential high-level nuclear waste repository on lands within and adjacent to the Nevada Test Site (NTS), Nye County, Nevada. The Design Verification Studies are performed to collect information during construction of the ESF that will be useful for design and construction of the potential repository. Four experiments make up the Design Verification Study: Evaluation of Mining Methods, Monitoring Drift Stability, Monitoring of Ground Support Systems, and The Air Quality and Ventilation Experiment. This report describes Sandia National Laboratories` (SNL) efforts in the first three of these experiments in the NRST.
This international directory of more than 500 photovoltaic-related manufacturers is intended to guide potential users of photovoltaics to sources for systems and their components. Two indexes help the user to locate firms and materials. A glossary describes equipment and terminology commonly used in the photovoltaic industry.
Sandia National Laboratories and Industrial Solar Technology are cost-sharing development of advanced parabolic trough technology. As part of this effort, several configurations of an IST solar collector were tested to determine the collector efficiency and thermal losses with black chrome and black nickel receiver selective coatings, combined with aluminized film and silver film reflectors, using standard Pyrex{reg_sign} and anti-reflective coated Pyrex{reg_sign} glass receiver envelopes. The development effort has been successful, producing an advanced collector with 77% optical efficiency, using silver-film reflectors, a black nickel receiver coating, and a solgel anti-reflective glass receiver envelope. For each receiver configuration, performance equations were empirically derived relating collector efficiency and thermal losses to the operating temperature. Finally, equations were derived showing collector performance as a function of input insolation value, incident angle, and operating temperature.
Solar Kinetics, Inc., has been developing a point-focus concentrating photovoltaic module and tracker system under contract to Sandia National Laboratories. The primary focus of the contract was to achieve a module design that was manufacturable and passed Sandia`s environmental testing. Nine modules of two variations were assembled, tested, and characterized in Phase 1, and results of these tests were promising, with module efficiency approaching the theoretical limit achievable with the components used. The module efficiency was 11.9% at a solar irradiance of 850 W/sq m and an extrapolated cell temperature of 25 C. Improvements in module performance are anticipated as cell efficiencies meet their expectations. A 2-kW tracker and controller accommodating 20 modules was designed, built, installed, and operated at Solar Kinetics` test site. The drive used many commercially available components in an innovative arrangement to reduce cost and increase reliability. Backlash and bearing play were controlled by use of preloaded, low slip-stick, synthetic slide bearings. The controller design used a standard industrial programmable logic controller to perform ephemeris calculations, operate the actuators, and monitor encoders.
The objective of the workshop was to promote discussions between experts and research managers on developing approaches for assessing the impact of DOE`s basic energy research upon the energy mission, applied research, technology transfer, the economy, and society. The purpose of this impact assessment is to demonstrate results and improve ER research programs in this era when basic research is expected to meet changing national economic and social goals. The questions addressed were: (1) By what criteria and metrics does Energy Research measure performance and evaluate its impact on the DOE mission and society while maintaining an environment that fosters basic research? (2) What combination of evaluation methods best applies to assessing the performance and impact of OBES basic research? The focus will be upon the following methods: Case studies, User surveys, Citation analysis, TRACES approach, Return on DOE investment (ROI)/Econometrics, and Expert panels. (3) What combination of methods and specific rules of thumb can be applied to capture impacts along the spectrum from basic research to products and societal impacts?