The A-primed (Agile Product Realization of Innovative electro-Mechanical Devices) project is defining and proving processes for agile product realization for the Department of Energy complex. Like other agile production efforts reported in the literature, A-primed uses concurrent engineering and information automation technologies to enhance information transfer. A unique aspect of our approach to agility is the qualification during development of a family of related product designs and their production processes, rather than a single design and its attendant processes. Applying engineering principles and statistical design of experiments, economies of test and analytic effort are realized for the qualification of the device family as a whole. Thus the need is minimized for test and analysis to qualify future devices from this family, thereby further reducing the design-to-production cycle time. As a measure of the success of the A-primed approach, the first design took 24 days to produce, and operated correctly on the first attempt. A flow diagram for the qualification process is presented. Guidelines are given for implementation, based on the authors experiences as members of the A-primed qualification team.
A method has been formulated and tested to provide laser weld schedules using a mathematical model and parameter optimization. This effort, on behalf of the Smartweld manufacturing initiative, seeks to provide: (1) laser power, (2) part travel speed, and (3) lens focal length to optimize weld process efficiency while constraining weld dimensions. Experimental data for three metals was fit to provide the mathematical model. Embedded material constants in the computational model allowed the extension to seven metals. A genetic algorithm, was used to accomplish the optimization. Lens focal length is a discrete variable and necessitated this type of algorithm. All coding was done in MATLAB and a graphical user interface was provided. Contour and surface plots, available through the interface, provide the analyst with insight as to optimum welds which are reachable within the problem-specified bounds on power, speed, and available focal lengths.
This paper is a presentation made in support of the statistics profession. This field can say it has had a major impact in most major fields of study presently undertaken by man, yet it is not perceived as an important, or critical field of study. It is not a growth field either, witness the almost level number of faculty and new PhD`s produced over the past twenty years. The author argues the profession must do a better job of selling itself to the students it educates. Awaken them to the impact of statistics in their lives and their business worlds, so that they see beyond the formulae to the application of these principles.
The System Surety Assessment Department 12332 of Sandia National Laboratories performed an independent nuclear safety assessment of the Non-nuclear Verification Instrument NNV-470AS. The NNV-470AS was assessed for structural integrity, characteristics of its electrical circuits, and its Radiated Electrical Emissions. Department 12332 concluded that the NNV-470AS and its Operational Procedures are safe to use with war reserve weapons. However, strict adherence to the Operational Procedures for the NNV-470AS is needed to prevent tampering with the instrument.
This document is a compilation of the Field Work Proposals (FWP) for the DOE BES Materials Sciences Program. The program is directed toward Scientifically Tailored Materials, specifically for energy applications.
MACCS was developed at Sandia National Laboratories (SNL) under U.S. Nuclear Regulatory Commission (NRC) sponsorship to estimate the offsite consequences of potential severe accidents at nuclear power plants (NPPs). MACCS was publicly released in 1990. MACCS was developed to support the NRC`s probabilistic safety assessment (PSA) efforts. PSA techniques can provide a measure of the risk of reactor operation. PSAs are generally divided into three levels. Level one efforts identify potential plant damage states that lead to core damage and the associated probabilities, level two models damage progression and containment strength for establishing fission-product release categories, and level three efforts evaluate potential off-site consequences of radiological releases and the probabilities associated with the consequences. MACCS was designed as a tool for level three PSA analysis. MACCS performs probabilistic health and economic consequence assessments of hypothetical accidental releases of radioactive material from NPPs. MACCS includes models for atmospheric dispersion and transport, wet and dry deposition, the probabilistic treatment of meteorology, environmental transfer, countermeasure strategies, dosimetry, health effects, and economic impacts. The computer systems MACCS is designed to run on are the 386/486 PC, VAX/VMS, E3M RISC S/6000, Sun SPARC, and Cray UNICOS. This paper provides an overview of MACCS, reviews some of the applications of MACCS, international collaborations which have involved MACCS, current developmental efforts, and future directions.
We present three codes for the Intel Paragon that address the problem of three-dimensional seismic imaging of complex geologies. The first code models acoustic wave propagation and can be used to generate data sets to calibrate and validate seismic imaging codes. This code reported the fastest timings for acoustic wave propagation codes at a recent SEG (Society of Exploration Geophysicists) meeting. The second code implements a Kirchhoff method for pre-stack depth migration. Development of this code is almost complete, and preliminary results are presented. The third code implements a wave equation approach to seismic migration and is a Paragon implementation of a code from the ARCO Seismic Benchmark Suite.
We have developed a new intracavity laser technique that uses a living or a fixed cell as an integral component of the laser. The cells are placed on an AlGaAs/GaAs surface-emitting semiconductor wafer and covered with a glass dielectric mirror to form a laser resonator. In this arrangement, the cells serve as optical waveguides (or lens elements) to confine (or focus) light generated in the resonator by the semiconductor. Because of the high transparency, the cells aid the lasing process to generate laser light. This ultra sensitive laser provides a novel imaging/spectroscopic technique for histologic examination which we demonstrate with normal and sickled human red blood cells. Extremely high contrast microscopic images of the cells are observed near 830-850 nm. These images correspond to electromagnetic modes of cell structures and are sensitive to shape of the cell. Using a high resolution spectrometer, we resolve the light emitted from these images into very narrow spectral peaks associated with the lasing modes. Analysis of the spectra reveals that the distribution of peaks is quite different for normal and sickled red blood cells. This technique, in a more developed form, may be useful for the rapid analysis of other kinds of normal and abnormal cells.
In 1992, a sinkhole was discovered above a Strategic Petroleum Reserve storage facility at Weeks Island, Louisiana. The oil is stored in an old salt mine located within a salt dome. In order to assess the hydrologic significance of the sink hole, an In Situ Permeable Flow Sensor was deployed within a sand-filled conduit in the salt dome directly beneath the sinkhole. The flow sensor is a recently developed instrument which uses a thermal perturbation technique to measure the magnitude and direction of the full 3-dimensional groundwater flow velocity vector in saturated, permeable materials. The flow sensor measured substantial groundwater flow directed vertically downward into the salt dome. The data obtained with the flow sensor provided critical evidence which was instrumental in assessing the significance of the sinkhole in terms of the integrity of the oil storage facility.
The World Wide Web provides a unified method of access to various information services on the Internet via a variety of protocols. Mosaic and other browsers give users a graphical interface to the Web that is easier to use and more visually pleasing than any other common Internet information service today. The availability of information via the Web and the number of users accessing it have both grown rapidly in the last year. The interest and investment of commercial firms in this technology suggest that in the near future, access to the Web may become as necessary to doing business as a telephone. This is problematical for organizations that use firewalls to protect their internal networks from the Internet. Allowing all the protocols and types of information found in the Web to pass their firewall will certainly increase the risk of attack by hackers on the Internet. But not allowing access to the Web could be even more dangerous, as frustrated users of the internal network are either unable to do their jobs, or find creative new ways to get around the firewall. The solution to this dilemma adopted at Sandia National Laboratories is described. Discussion also covers risks of accessing the Web, design alternatives considered, and trade-offs used to find the proper balance between access and protection.
Sandia is a multiprogram engineering and science laboratory operated for the Department of Energy with major facilities at Albuquerque, New Mexico, and Livermore, California, and a test range near Tonapah, Nevada. It has major research and development responsibilities for nuclear weapons, arms control, energy, the environment, economic competitiveness, and other areas of importance to the needs of the nation. The principal mission is to support national defense policies by ensuring that the nuclear weapon stockpile meets the highest standards of safety, reliability, security, use control, and military performance. This publication gives a brief overview of the multifaceted research programs conducted by the laboratory.
The SANdia total-DOSe Estimator (SANDOSE) is used to estimate total radiation dose to a (BRL-CAT) solid model, SANDOSE uses the mass-sectoring technique to sample the model using ray-tracing techniques. The code is integrated directly into the BRL-CAD solid model editor and is operated using a simple graphical user interface. Several diagnostic tools are available to allow the user to analyze the results. Based on limited validation using several benchmark problems, results can be expected to fall between a 10% underestimate and a factor of 2 overestimate of the actual dose predicted by rigorous radiation transport techniques. However, other situations may be encountered where the results might fall outside of this range. The code is written in C and uses X-windows graphics. It presently runs on SUN SPARCstations, but in theory could be ported to any workstation with a C compiler and X-windows. SANDOSE is available via license by contacting either the Sandia National Laboratories Technology Transfer Center or the author.
The Environmental Restoration (ER) Project at Sandia National Laboratories, New Mexico is managing the project to assess and, when necessary, to remediate sites contaminated by the lab operations. Within the ER project, the site-wide hydrogeologic characterization task is responsible for the area-wide hydrogeologic investigation. The purpose of this task is to reduce the uncertainty about the rate and direction of groundwater flow beneath the area and across its boundaries. This specific report deals with the installation of PGS-1 monitoring well which provides information on the lithology and hydrology of the aquifer in the northern area of the Kirtland Air Force Base. The report provides information on the well design; surface geology; stratigraphy; structure; drilling, completion, and development techniques; and borehole geophysics information.
The US Department of Energy (DOE) is preparing to request the US Environmental Protection Agency to certify compliance with the radioactive waste disposal standards found in 40 CFR Part 191 for the Waste Isolation Pilot Plant (WIPP). The DOE will also need to demonstrate compliance with a number of other State and Federal standards and, in particular, the Land Disposal Restrictions of the Resource Conservation and Recovery Act (RCRA), 40 CFR Part 268. Demonstrating compliance with these regulations requires an assessment of the long-term performance of the WIPP disposal system. Re-evaluation and extension of past scenario development for the WIPP forms an integral part of the ongoing performance assessment (PA) process.
Radiation in participating media is an important transport mechanism in many physical systems. The simulation of complex radiative transfer has not effectively exploited high-performance computing capabilities. In response to this need, a workshop attended by members active in the high-performance computing community, members active in the radiative transfer community, and members from closely related fields was held to identify how high-performance computing can be used effectively to solve the transport equation and advance the state-of-the-art in simulating radiative heat transfer. This workshop was held on March 29-30, 1994 in Albuquerque, New Mexico and was conducted by Sandia National Laboratories. The objectives of this workshop were to provide a vehicle to stimulate interest and new research directions within the two communities to exploit the advantages of high-performance computing for solving complex radiative heat transfer problems that are otherwise intractable.
Perimeter intrusion detection systems are an integral part of most physical security systems. Sandia National Laboratories, under the sponsorship of the U.S. Department of Energy, Office of Safeguards and Security; the U.S. Military Services; and many other U.S. Government Agencies, has over the last 20 years conducted surveys of available perimeter intrusion detection sensors and has tested many of the sensors manufactured in the United States and other countries. An overview of the newer and more advanced technologies employed in these sensors is provided.
An ovenized 10 pF standard capacitor was constructed by the National Institute of Standards and Technology (NIST). The dielectric material used as Wuprasil II grade fused silica. This report discusses a temperature coefficient analysis of the capacitor performed at the Primary Standards Laboratory (PSL) of Sandia National Laboratories (SNL). The effects of temperature change on dielectric loss will also be discussed.
A common limitation to performance in data acquisition systems is storage of the collected data. Compressing the data would increase the amount of data that could be stored. However, most compression routines require that the data be collected and analyzed before compression is performed. Also, these compression routines often store the information required for decompression along with the data, thus decreasing the storage available for data. One solution to this problem is to create an encoding tree known to both the encoder and the decoder based on apriori knowledge of the data. Once the tree is created, optimal encoding schemes such as the Huffman algorithm may be used on the data as it is being collected. In this way the data is compressed as each byte is received and there is no overhead associated with storing decompression data. In this paper the idea of using a fixed Huffman tree is explored and the results are compared to a defacto standard in data compression, PKZIP.
A microscopic theory, that is based on the coupled Maxwell-semiconductor-Bloch equations, is used to investigate the effects of many-body Coulomb interactions in semiconductor laser devices. This paper describes two examples where the many-body effects play important roles. Experimental data supporting the theoretical results are presented.
Collection of Technical Papers - AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics and Materials Conference
James, G.; Mayes, R.; Carne, T.; Simmermacher, T.; Goodding, J.
Two techniques for damage localization (Structural Translational and Rotational Error Checking - STRECH and MAtriX COmpletioN - MAXCON) are described and applied to operational structures. The structures include a Horizontal Axis Wind Turbine (HAWT) blade undergoing a fatigue test and a highway bridge undergoing an induced damage test. STRECH is seen to provide a global damage indicator to assess the global damage state of a structure. STRECH is also seen to provide damage localization for static flexibility shapes or the first mode of simple structures. MAXON is a robust damage localization tool using the higher order dynamics of a structure. Several options are available to allow the procedure to be tailored to a variety of structures.
Proceedings of SPIE - The International Society for Optical Engineering
Smith, R.E.; Warren, M.E.; Wendt, J.R.; Vawter, G.A.
We have fabricated sub-wavelength diffractive optical elements with binary phase profiles for operation at 975 nm. Blazed transmission gratings with minimum features 63 nm wide were designed by using rigorous coupled-wave analysis and fabricated by direct-write e-beam lithography and reactive ion beam etching in gallium arsenide. Transmission measurements show 85% diffraction efficiency into the first order. Anti-reflection surfaces, with features 42 nm wide were also designed and fabricated.
Emissive flat panel display systems operating in full color demand higher performance at low voltages (ca. 50 - 1000 V) from cathodoluminescent (CL) phosphors than cathode ray tubes require. Hydrothermal synthesis has been suggested as a route to phosphors with improved efficiencies, lower voltage thresholds, and increased saturation power. This hypothesis was tested in europium-doped yttrium orthovanadate (YVO4:Eu), an efficient, red emitting CL phosphor. The CL efficiency of YVO4:Eu crystallized from aqueous solution at 200°C is relatively low until it is annealed. The distribution of particle sizes in the low-temperature phosphor is similar to that in material made via a solid-state route, but crystallites remain much smaller (ca. 400 angstrom) until they are annealed. These observations, along with the anomalously strong dependence of CL intensity on europium concentration, support a model in which efficiency principally depends on crystallite size. CL efficiency of both solid state and hydrothermal YVO4:Eu increases with voltage at constant power. Surface-bound electrons are likely the dominant influence on efficiency at voltages near threshold. Saturation power is independent of synthetic route. It is apparent that the CL properties of hydrothermally synthesized YVO4:Eu are essentially the same as those of YVO4:Eu produced via conventional, high-temperature routes.
Experiments have been conducted with a molten salt loop at Sandia National Laboratories in Albuquerque, NM to resolve issues associated with the operation of the 10MW{sub e} Solar Two Central Receiver Power Plant located near Barstow, CA. The salt loop contained two receiver panels, components such as flanges and a check valve, vortex shedding and ultrasonic flow meters, and an impedance pressure transducer. Tests were conducted on procedures for filling and thawing a panel, and assessing components and instrumentation in a molten salt environment. Four categories of experiments were conducted: (1) cold filling procedures, (2) freeze/thaw procedures, (3) component tests, and (4) instrumentation tests. Cold-panel and -piping fill experiments are described, in which the panels and piping were preheated to temperatures below the salt freezing point prior to initiating flow, to determine the feasibility of cold filling the receiver and piping. The transient thermal response was measured, and heat transfer coefficients and transient stresses were calculated from the data. Freeze/thaw experiments were conducted with the panels, in which the salt was intentionally allowed to freeze in the receiver tubes, then thawed with heliostat beams. Slow thermal cycling tests were conducted to measure both how well various designs of flanges (e.g., tapered flanges or clamp type flanges) hold a seal under thermal conditions typical of nightly shut down, and the practicality of using these flanges on high maintenance components. In addition, the flanges were thermally shocked to simulate cold starting the system. Instrumentation such as vortex shedding and ultrasonic flow meters were tested alongside each other, and compared with flow measurements from calibration tanks in the flow loop.
Switchable polarization can be significantly suppressed in ferroelectric (FE) materials by optical, thermal, and electrical processes. The thermal process can occur by either annealing the FE in a reducing environment or by heating it in air to 100 °C while impressing a bias near the switching threshold. The optical process occurs while biasing the FE near the switching threshold and illuminating with bandgap light. And the electrical suppression effect occurs by subjecting the FE to repeated polarization reversals. Using electron paramagnetic resonance, polarization-voltage measurements, and charge injection scenarios, we have been able to elucidate both electronic and ionic trapping effects that lead to a suppression in the amount of switchable polarization in FE materials. The relative roles of electronic and ionic effects in the same material can depend on the stress condition. For instance, in oxidized BaTiO3 crystals, optical and thermal suppressions occur by electronic domain pinning; electrical fatigue in the BaTiO3 crystals also appears to involve electronic charge trapping, however, it is suggested that these electronic traps are further stabilized by nearby ionic defects. In sol-gel PZT thin films with either Pt, RuO2, or La-Sr-Co-O electrodes it appears that the polarization suppression induced by electrical fatigue, a temperature/bias combination, or a light/bias combination are all primarily due to the trapping of electronic charge carriers to first order.
Scannerless range imaging (SRI) is a unique approach to three dimensional imaging without scanners. SRI does, however, allow a more powerful light source to be used as compared to conventional laser radar (LADAR) systems due to the speed of operation associated with this staring system. As a result, a more efficient method of operation was investigated. As originally conceived, SRI transmits a continuous intensity modulated sinusoidal signal; however, a square wave driver is more energy efficient than a sinusoidal driver. In order to take advantage of this efficiency, a square wave operational methodology was investigated. As a result, four image frames are required for the extraction of range using a square wave to unambiguously resolve all time delays within one time period compared to a minimum of three frames for the sinusoidal wave.
The most common tool used by aircraft inspectors is the personal flashlight. While it is compact and very portable, it is generally typified by poor beam quality which can interfere with the ability for an inspector to detect small defects and anomalies, such as cracks and corrosion sites, which may be indicators of major structural problems. A Light Shaping Diffuser TM (LSD) installed in a stock flashlight as a replacement to the lens can improve the uniformity of an average flashlight and improve the quality of the inspection. Field trials at aircraft maintenance facilities have demonstrated general acceptance of the LSD by aircraft inspection and maintenance personnel.
Several studies have shown that the surface morphology can be smoother during simultaneous ion bombardment and growth than during growth alone, however, the atomistic mechanism responsible for the smoothing effect has been difficult to determine. We have developed Monte Carlo simulations of growth and defect diffusion to model the interaction between growth atoms and ion-induced defects and to present a simple atomistic mechanism that describes the effects of low-energy ion bombardment during ion-assisted growth of germanium. Measurements of ion-induced point defect production indicate that a large number of defects exist only temporarily on the surface at typical growth temperatures, because the defects have sufficient mobility to recombine and annihilate. We propose that this ion-induced transient defect population plays a significant role in modifying the dynamic surface morphology. The simulations support a surface smoothing mechanism that involves the destabilization of adatom islands by the transient ion-induced defects. The optimum simulated steady-state surface morphology can be achieved with ion-induced defect production rates less than or equal to 10 defects/ion. We find that low-energy ion bombardment during growth effectively lowers the temperature at which step-flow growth can be achieved.
We have characterized the optical properties of heteroepitaxial Si1-xCx and Si0.924-xGe0.076Cx (0≤x≤0.014) alloys grown on Si substrates by solid phase epitaxy using spectroscopic ellipsometry. The measured dielectric function confirms that the samples are of good crystalline quality. We determined the E1 and E2 band gaps by lineshape-fitting the features in the second derivative spectra of the dielectric functions. Also, we discuss the shift of the band gaps with C concentration arising from strain and chemical alloying.
A dry barrier may be formed by circulating dry air through a soil layer above or below a waste disposal site, thus reducing the soil moisture content to very low values. Drying a horizontal soil layer creates a barrier to vertical water movement in three ways. First, the drying removes water from the system, intercepting water infiltrating down from the surface. Second, drying a soil layer increases its water storage capacity so the soil will tend to retain rather than transmit water. Third, as a soil layer dries, moisture is removed from progressively smaller interstitial pores so that the hydraulic conductivity of the formation (for liquid flow) decreases. For example, the hydraulic conductivity of a typical sand may decrease by three orders of magnitude as its moisture content is reduced from 20 to 10 percent. This study analyzed the technical and economic feasibility of the subsurface dry barrier concept for containment of a migrating contaminant plume in unsaturated soil. The concept was shown to be a viable option for limiting aqueous migration of pollutants through unsaturated media, with estimated capital costs of between $130,000 and $260,000 for a 1-hectare barrier, and annual operating costs of $10,000 per year.
Inferring phylogenetic trees is a fundamental problem in computational-biology. We present a new objective criterion, the phylogenetic number, for evaluating evolutionary trees for species defined by biomolecular sequences or other qualitative characters. The phylogenetic number of a tree T is the maximum number of times that any given character state arises in T. By contrast, the classical parsimonycriterion measures the total number of times that different character states arise in T. We consider the following related problems: finding the tree with minimum phylogenetic number, and computing the phylogenetic number of a given topology in which only the leaves are labeled by species. When the number of states is bounded (as is the case for biomolecular sequence characters), we can solve the second problem in polynomial time. We can also compute a fixed-topology 2-phylogeny (when one exists) for an arbitrary number of states. This algorithm can be used to further distinguish trees that are equal under parsimony. We also consider a number of other related problems.
The NASA Standard Detonator (NSD) is employed in support of a number of current applications, including the Space Shuttle. This effort was directed towards providing test results to characterize the output of this device for its use in a safe and arm device. As part of the investigation, flash X-ray was used to provide stop-motion photographs of the flying metal plate that is created by initiation of the detonator. This provided researchers with a better understanding of the shape and character of the high- velocity disk as it propagated across the gap between the detonator and next assembly. The second portion of the study used a velocity interferometer to evaluate the acceleration and velocity histories of the flying plate, providing a quantified assessment of the detonator’s ability to initiate the explosive in the next explosive.
For many years, explosive components have used hotwires to convert an electrical stimulus into the thermal energy required to initiate the device. A Semi-conductor Bridge (SCB) performs the same function, but with the advantage of requiring approximately 1/10 the input energy of a comparable hotwire, while retaining excellent no-fire characteristics. The SCB also demonstrates faster function times due to its inherently-lower thermal mass. This paper discusses the development and production of two SCB-based devices, the MC4491 Initiator and the MC4492 Actuator. The initiator is designed to shock initiate a linear shaped charge by accelerating a thin metal plate across a small gap. The actuator functions several different components, sewing as either an actuator by producing a rapidly expanding gas to activate piston mechanisms or as an ignitor by providing hot particles for initiating pyrotechnic mixtures. Details are provided on the construction of both devices, methods of assembly, and performance characteristics (function time, flyer velocity, pressure in a closed bomb, heat content, and no-fire and all-fire levels).
As photovoltaic (PV) systems gain more acceptance in utility-interactive applications throughout the world, many organizations are placing increasingly higher priorities on writing guidelines, codes and standards. These guidelines and codes are being written to improve safety, installation, acceptance, listing or certification of the PV components or systems. Sandia National Laboratories` PV System Applications Department is working closely with the PV industry to address issues that are associated with fire and personnel safety and with National Electrical Code (NEC) requirements. Additionally, the United States has agreed to participate in two of the International Energy Agency (IEA) Annexes (topical tasks) of the Implementing Agreement for a Cooperative Programme on Photovoltaic Power Systems. This paper describes events and activities associated with the NEC and the IEA that are being led by Sandia National Laboratories with broad participation by the US PV industry.
Proceedings of the IEEE International Symposium on Assembly and Task Planning
Hwang, Yong K.
We present a motion planner for multiple moving objects in two dimensions. The search for collision-free paths is performed in the composite configuration space of all the moving objects to guarantee a solution, and the efficiency of our planner is demonstrated with examples. Our motion planner can be characterized with a hierarchical, multi-resolution search of the configuration space along with a generate-and-test paradigm for solution paths. Because of the high dimensionality of the composite configuration space, our planner is most useful for cases with a small number of moving objects. Some of the potential applications are navigation of several mobile robots, and planning part motions for a multi-handed assembly operation.
A method is reported for generating mechanical spacecraft propulsion from unsymmetrical magnetic induction fields. It is based on an unsymmetrical three-dimensional loop antenna structure driven by a repetitively-pulsed high-current power supply. Antenna geometry is optimized for generating propulsive thrust rather than radiating electromagnetic energy. Part of this antenna consists of flat electrical conductors, which form a partially-closed quasi-cylindrical volume around a center conductor. Magnetic flux concentrates at the closed end of the quasi-cylindrical volume thereby creating a magnetic field flux density gradient along a single axis collinear to the Center Conductor. This magnetic field density gradient imbalances the magneto-mechanical forces that result from the interactions of the internal magnetic induction field with the current in the conductors of the antenna structure, in accordance with Lorentz’s Force Law. Also, there are electrically isolated prismatic conductor surfaces attached to the inside surface of the flat conductors which form the closed end of the quasi-cylindrical volume. Mechanical pressures occur on these conductor prisms because of the changing internal magnetic field and are a consequence of Faraday’s Induction Law and Lenz’s Law. Input current rise time and wave shape are crucial to maximizing spacecraft propulsive thrust.
Proceedings of the IEEE International Symposium on Assembly and Task Planning
Hwang, Yong K.
There have been numerous research efforts in the field of motion planning, resulting in many theoretical and practical results. We review the current status of existing motion planning algorithms, evaluate their completenesses and efficiencies on modern computers, and suggest fruitful future research directions.
The semiconductor bridge, SCB, developed by Sandia National Laboratories is a maturing technology now being used in several applications by Sandia customers. Most applications arose because of a need at the system level to provide explosive assemblies that were light weight, small volume, low cost and required small quantities of electrical energy to function — for the purposes of this paper we define an explosive assembly to mean the combination of the firing set and an explosive component. As a result, and because conventional firing systems could not meet the stringent size, weight and energy requirements of our customers, we designed and are investigating SCB applications that range from devices for Sandia applications to igniters for fireworks. We present in this paper an overview of SCB technology with specific examples of the systems designed for our customers to meet modern requirements that sophisticated explosive systems must satisfy in today’s market environments.
Land subsidence. Proc. international symposium, The Hague, 1995
Neal, J.T.
A sinkhole was observed over the edge of the two-level former salt mine that was converted for oil storage. Diagnostic studies suggest a direct connection exists between the surface collapse area and the underground mine as shown by correlative measurements of sediment slump rates and probable brine influx into the mine. The dissolution of salt below the sinkhole that initiated the leak into the mine was likely caused by several confluent geologic processes, and exacerbated by mining-induced stresses that created fractures which served as hydrologic flowpaths. Modelling studies of mine stresses show that years may be required before tensional cracking begins to occur, but once begun can continue to develop, and relieve the stress in that specific regime. The crack regime creates the avenue for incursion of groundwater. Mitigation measures include increasing the mine pressure, slowing the dissolution by injecting brine into the sinkhole throat, and construction of a freeze curtain to restrict hydrologic flowpaths. -from Authors
A general method for applying command shaping to various multiple degree of freedom cranes is described such that the payload moves to a specified point without residual oscillation. A dynamic programming is used for general command shaping for optimal maneuvers. The results taken are compared to near-optimal solutions where the commands are linear combinations of accelerations pulse basis functions. Simulation results and experimental verification for a variable load-line length rotary crane are also presented using design procedures.
The issues of verification, calibration, and validation of computational fluid dynamics (CFD) codes has been receiving increasing levels of attention in the research literature and in engineering technology. Both CFD researchers and users of CFD codes are asking more critical and detailed questions concerning the accuracy, range of applicability, reliability and robustness of CFD codes and their predictions. This is a welcomed trend because it demonstrates that CFD is maturing from a research tool to the world of impacting engineering hardware and system design. In this environment, the broad issue of code quality assurance becomes paramount, However, the philosophy and methodology of building confidence in CFD code predictions has proven to be more difficult than many expected. A wide variety of physical modeling errors and discretization errors are discussed. Here, discretization errors refer to all errors caused by conversion of the original partial differential equations to algebraic equations, and their solution. Boundary conditions for both the partial differential equations and the discretized equations will be discussed. Contrasts are drawn between the assumptions and actual use numerical method consistency and stability. Commen are also made concerning the existence and uniqueness solutions for both the partial differential equations and the discrete equations. Various techniques are suggested for the detection and estimation of errors caused by physical modeling and discretization of the partial differential equations.
Carbon Nitride (CNx) films have been grown by ion-assisted pulsed-laser deposition (IAPLD). Graphite targets were laser ablated while bombarding the substrate with ions from a broad-beam Kaufman-type ion source. The ion voltage, current density, substrate temperature, and feed gas composition (N2 in Ar) have been varied. The resultant films were characterized by Raman, Fourier transform infrared (FTIR), and Rutherford back scattering (RBS) spectroscopy. Samples with ≈30% N/C ratio have been fabricated. The corresponding Raman and FTIR spectra indicate that nitrogen is incorporated into the samples by insertion into sp2- bonded structure. A low level of C≡N triple bonds is also found. As the ion current and voltage are increased with a pure Ar ion beam, Raman peaks associated with nanocrystalline graphite appear in the spectra. Adding low levels of nitrogen to the ion beam first reduces the Raman intensity in the vicinity of the graphite disorder peak without adding detectable amounts of nitrogen to the films (as measured by RBS). At higher nitrogen levels in the ion beam, significant amounts of nitrogen are incorporated into the samples, and the magnitude of the ″disorder″ peak increases. By increasing the temperature of the substrate during deposition, the broad peak due mainly to sp2-bonded C-N in the FTIR spectra is shifted to lower wavenumber. This could be interpreted as evidence of single-bonded C-N; however, it is more likely that the character of the sp2 bonding is changing.
Extensive surface pressure measurements were obtained on a hypersonic vehicle configuration at Mach 8. All of the experimental results were obtained in the Sandia National Laboratories Mach 8 hypersonic wind tunnel for lamipar boundary layer conditions. The basic vehicle configuration IS a spherically blunted 100 half-angle cone with a slice parallel with the axis of the vehicle. The bluntness ratio of the geometly IS 10% and the slice begins at 70% of the length of the vehicle. Surface pressure measurements were obtained for angles of attack from -10 to +180. for various roll angles, at 96 locations on the body surface. A new and innovative uncertainty analysis was devised to estimate the contributors to surface pressure meaSment uncenainty. Quantitative estimates were computed for the uncertainty contributions due to the complete insmmentation system, nonunifoxmity of flow in the test section of the wind Nnnel. and variations in the wind tunnel model. This extensive set of high-quality surface pressure measurements is recommended for use in the calibration and validation of computational fluid dynamics codes for hyuersonic flow conditions.
The chemical inertness and high bond strengths of the 3-5 nitrides lead to slower plasma etching rates than for more conventional 3-5 semiconductors under the same conditions. High ion density conditions (greater than 3 x 10(exp 11) cm(exp {minus}3)) such as those obtained in ECR or magnetron reactors produce etch rates up to an order of magnitude higher than for RIE, where the ion densities are in the 10(exp 9) cm(exp {minus}3) range. The authors have developed smooth anisotropic dry etches for GaN, InN, AlN and their alloys based on Cl2/CH4/H2/Ar, BCl3/Ar, Cl2/H2, Cl2/SF6, HBr/H2 and HI/H2 plasma chemistries achieving etch rates up to approx. 4,000 A/min at moderate dc bias voltages (less than or equal to {minus}150 V). Ion-induced damage in the nitrides appears to be less apparent than in other 3-5`s. One of the key remaining issues is the achievement of high selectivities for removal of one layer from another.
Quantum well microdisk laser structures have been fabricated in the GaN/InGaN, GaAs/AlGaAs and GaAs/InGaP systems using a combination of ECR dry etching Cl2/CH4/H2/Ar, BCl3/Ar or CH4/H2/Ar plasma chemistries respectively, and subsequent wet chemical etching of a buffer layer underlying the quantum wells. While wet etchants such as HF/H2O and HCl/HNO3/H2O are employed for AlGaAs and InGaP, respectively, a new KOH based solution has been developed for AlN which is completely selective over both GaN and InGaN. Typical mask materials include PR or SiN(x), while the high surface recombination velocity of exposed AlGaAs (approximately) 10(exp 5)cm(center dot)/sec requires encapsulation with ECR-CVD SiN(x) to stabilize the optical properties of the modulators.
This [updated 1/95] report outlines the technology of modern solar central receiver power plants, showing how they could be an important domestic source of energy within the next decade
With all the advances in the microelectronics industry, a limiting factor to computer chip speed and size is becoming the dielectric constant of the interlayer insulating materials. Dielectric constants of these layers have been reduced in going from inorganic to organic type materials. A further reduction in dielectric constant, coupled with better mechanical properties are still required for these types of materials. The authors have developed a technique involving spincoating in conjunction with a thermodynamic process called {open_quotes}Non-solvent Induced Phase Separation{close_quotes} (NSIPS) to create microporous polyimide films that exhibit both a lower dielectric constant and better stress reduction properties compared to their solid film counterparts. In this technique, the authors spincoat a soluble polyimide solution in 1,3-dimethoxybenzene solvent onto a silicon wafer, and then immediately submerse the {open_quotes}wet{close_quotes} polymer film into a non-solvent bath, typically toluene. Phase separation of the polymer occurs on a micron size scale and the resulting microporous structure becomes locked in by the high glass transition temperature of the polyimide. The authors have determined the factors affecting the film morphology, thickness, pore size, and percent porosity; these factors include the polymer concentration, spin speed, and the type of non-solvent used. The different morphologies obtained for the varying non-solvents are explained in terms of thermodynamics and kinetics of phase separation and diffusion, using an idealized ternary phase diagram. One particular film having a porosity of 68%, thickness of 22 microns and pore size of 1.4 microns had a measured dielectric constant of 1.88 and dielectric loss of 0.002. Stress measurements indicated that the microporous film reduced surface stress on the wafer by more than a factor of 10 when compared to the analogous solid polyimide film.
A major objective of the Nuclear Regulatory Commission`s (NRC) Individual Plant Examination (IPE) Insights Program is to identify the important determinants of core damage frequency (CDF) for the different reactor and containment types and plant designs as indicated in the IPEs. The human reliability analysis (HRA) is a critical component of the probabilistic risk assessments (PRAS) which were done for the IPES. The determination and selection of human actions for incorporation into the event and fault tree models and the quantification of their failure probabilities can have an important impact on the resulting estimates of CDF and risk. Therefore, two important goals of the NRCs IPE Insights Program are (1) to determine the extent to which human actions and their corresponding failure probabilities influenced the results of the IPEs and (2) to identify which factors played significant roles in determining the differences and similarities in the results of the HRA analyses across the different plants. To obtain the relevant information, the NRC`s IPE database, which contains information on plant design, CDF, and containment performance obtained from the IPES, was used in conjunction with a systematic examination of the HRA analyses and results from the IPES. Regarding the extent to which the results of the HRA analyses were significant contributors to the plants` CDFs, examinations of several different measures indicated that while individual human actions could have important influences on CDF for particular initiators, the HRA results did not appear to be the most significant driver of plant risk (CDF). Another finding was that while there were relatively wide variations in the calculated human error probabilities (HEPs) for similar events across plants, there was no evidence for any systematic variation as a function of the HRA methods used in the analyses.
SEMATECH and the Department of Energy have established a Contamination Free Manufacturing Research Center (CFMRC) located at Sandia National Laboratories. One of the programs underway at the CFMRC is directed towards defect reduction in semiconductor process reactors by the application of computational modeling. The goal is to use fluid, thermal, plasma, and particle transport models to identify process conditions and tool designs that reduce the deposition rate of particles on wafers. The program is directed toward defect reduction in specific manufacturing tools, although some model development is undertaken when needed. The need to produce quantifiable improvements in tool defect performance requires the close cooperation among Sandia, universities, SEMATECH, SEMATECH member companies, and equipment manufacturers. Currently, both plasma (e.g., etch, PECVD) and nonplasma tools (e.g., LPCVD, rinse tanks) are being worked on under this program. In this paper the authors summarize their recent efforts to reduce particle deposition on wafers during plasma-based semiconductor manufacturing.
This is the final report on a series of experiments concerned with transient radiation-induced absorption in materials for a Cr,Nd:GSGG laser. Both the Sandia National Laboratories SPR III pulsed reactor and the Hermes III pulsed X-ray machine are used as radiation sources. The time dependence and the magnitude of the induced absorption in filter glasses and in doped and undoped LiNbO{sub 3} Q-switch materials have been measured. Gain has been observed in Cr,Nd:GSGG, the laser medium, when it is irradiated by X-rays.
Materials Research Society Symposium - Proceedings
Chason, E.
Understanding the evolution of porous silicon (PS) layers at the early stages of growth is important for determining the mechanism of PS film growth and controlling the film properties. We have used X-ray reflectivity (XRR) to determine the evolution of layer thickness and interfacial roughness during the growth of thin PS layers (< 200 nm) prepared by electrochemical anodization. The porous layer grows at a constant rate for films as thin as 15 nm indicating a very short incubation period during which the surface may be electropolished before the PS structure begins to form. Interface roughness measurements indicate that the top surface of the film remains relatively smooth during growth while the roughness of the PS/silicon interface increases only slightly with film thickness. The XRR results are compared with results obtained from the same films by cross-sectional transmission electron microscopy (XTEM), atomic force microscopy (AFM) and gravimetry.
We have used {sup 13}C magic-angle spinning (MAS) nuclear magnetic resonance (NMR) to characterize the structure and rotational dynamics of C{sub 60} containing oxygen molecules located in the interstitial sites of the fcc lattice. Under normal conditions, a narrow peak at 143.7 ppm is observed for C{sub 60}. When exposed to oxygen at moderate pressures, several additional resonances appear in the {sup 13}C MAS NMR spectrum. These secondary resonances are shifted downfield from the main peak at 143.7 ppm and are due to the Fermi-contact interaction of the paramagnetic oxygen molecules with the {sup 13}C nuclear spins. The presence of oxygen depresses the orientational ordering transition by ca. 20 K as observed by DSC. The spin-lattice relaxation time (T{sub 1}) of each secondary peak shows a minimum near the ordering transition, indicating that this transition is not dependent on the number of oxygen molecules surrounding an individual C{sub 60} molecule. The T{sub 1}, due to paramagnetic relaxation, normalized by the number of surrounding oxygen molecules, is constant. This observation demonstrates that within a given sample, the dynamics of C{sub 60} molecules are independent of the number of surrounding oxygen molecules.
This paper describes a process of combining two state-of-the-art CFD tools, SPRINT and INCA, in a manner which extends the utility of both codes beyond what is possible from either code alone. The speed and efficiency of the PNS code, SPRINT, has been combined with the capability of a Navier-Stokes code to model fully elliptic, viscous separated regions on high performance, high speed flight systems. The coupled SPRINT/rNCA capability is applicable for design and evaluation of high speed flight vehicles in the supersonic to hypersonic speed regimes. This paper describes the codes involved, the interface process and a few selected test cases which illustrate the SPRINT/INCA coupling process. Results have shown that the combination of SPRINT and INCA produces correct results and can lead to improved computational analyses for complex, three-dimensional problems.
Sampling during environmental drilling is essential to fully characterize the spatial distribution and migration of near surface contaminants. However, the analysis of these samples is not only expensive, but can take weeks or months when sent to an off-site laboratory. In contrast, measurement-while-drilling (MWD) screening capability could save money and valuable time by quickly distinguishing between contaminated and uncontaminated areas. Real-time measurements provided by a MVM system would enable on-the-spot decisions to be made regarding sampling strategies, enhance worker safety, and provide the added flexibility of being able to ``steer`` the drill bit in or out hazardous zones. During measurement-while-drilling, down-hole sensors are located behind the drill bit and linked by a rapid data transmission system to a computer at the surface. As drilling proceeds, data are collected on the nature and extent of the subsurface contamination in real-time. The down-hole sensor is a Geiger-Mueller tube (GMT) gamma radiation detector. In addition to the GMT signal, the MWD system monitors these required down-hole voltages and two temperatures associated with the detector assembly. The Gamma Ray Detection System (GRDS) and electronics package are discussed in as well as the results of the field test. Finally, our conclusions and discussion of future work are presented.
The effect of the pump, signal, and idler wave phases on three-wave nonlinear parametric mixing is investigated in a series of single-pass- gain experiments. Measurements are made with two angle-tuned KTP crystals in a 532 nm pumped, walkoff-compensated, optical parametric amplifier that is seeded by an 800 nm cw diode laser. In one of the measurements the second crystal is orientated to have its effective nonlinearity deff. of opposite sign to that of the first crystal, so that all mixing that occurred in the first crystal is canceled by the second when the phase mismatch Δkcrystal 1 = Δkcrystal 2 = 0. Efficient two-crystal amplification is subsequently restored by selecting the correct phase relationship for the three waves entering the crystal by inserting a dispersive plate between the crystals. The experimental results are explained in a straightforward manner with diagrams involving the three input wave polarizations. These results demonstrate that walkoff-compensated geometries require phase correction to achieve efficient mixing in the second crystal whenever the nonlinear interaction involves two extraordinary waves (e-waves). One practical application of this work may be lower oscillation thresholds and enhanced performance in walkoff-compensated optical parametric oscillators which use two e-waves.
This report summarizes two approaches to time-optimal control of a nonlinear magnetically levitated platen. The system of interest is a candidate technology for next-generation photolithography machines used in the manufacture of integrated circuits. The dynamics and the variable peak control force of the electro-magnetic actuators preclude the direct application of classical time-optimal control methodologies for determining optimal rest-to-rest maneuver strategies. Therefore, this study explores alternate approaches using a previously developed computer simulation. In the first approach, conservative estimates of the available control forces are used to generate suboptimal switching curves. In the second approach, exact solutions are determined iteratively and used as a training set for an artificial neural network. The trained network provides optimal actuator switching times that incorporate the full nonlinearities of the magnetic levitation actuators. Sample problems illustrate the effectiveness of these techniques as compared to traditional proportional-derivative control.
The Critical Dynamics in Microgravity Experiment, DYNAMX, is under development for space flight at Sandia National Laboratories and the University of New Mexico with Dr. Rob Duncan as the Principal Investigator. This experiment will investigate the effects on the superfluid transition in 4He of currents generated by heat flow, measuring the thermal conductivity in the fluid as a function of applfed heat. DYNAMX will also take advantage of the weightless environment to measure the conductivity properties in the region of the interface between the two phases. Thus, DYNAMX represents an experiment that will explore a system driven far from equilibrium. The experiment development is sponsored by the Microgravity Science and Applications Division of NASA, with the Jet Propulsion Laboratory as the managing center. This paper will describe the science objectives, the current design of the experiment apparatus, the steps being taken to prepare this experiment for flight, and the results of ground-based feasibility demonstrations now underway.
We present magnetoluminescence data which provides a quantitative measure of the energy- band dispersion curves of novel compound semiconductor optoelectronic materials. Data for a n-type strained-layer InGaAs/GaAs (quantum-well width approximately 8 nm) and a n-type 4.5 nm-wide GaAs/AlGaAs lattice-matched single-quantum well are presented. We find that the conduction-bands are almost parabolic, with a mass of about 0.068m0 for the GaAs/AlGaAs structure. The valence-bands are nonparabolic with wave vector dependent in- plane valence-band masses varying from about 0.1m0 at zone center to about 0.3m0 for 20 meV energies.
Materials Research Society Symposium - Proceedings
Schwartz, Robert W.
Sol-gel processing methods are frequently used for the fabrication of lead zirconate titanate (PZT) thin films for many electronic applications. Our standard approach for film fabrication utilizes lead acetate and acetic acid modified metal alkoxides of zirconium and titanium in the preparation of our precursor solutions. This report highlights some of our recent results on the effects of the addition of a second chelating ligand, acetylacetone, to this process. We discuss the changes in film drying behavior, densification and ceramic microstructure which accompany acetylacetone additions to the precursor solution and relate the observed variations in processing behavior to differences in chemical precursor structure induced by the acetylacetone ligand. Improvements in thin film microstructure, ferroelectric and optical properties are observed when acetylacetone is added to the precursor solution.
Active control of structures has been under intensive development for the last ten years. Reference 2 reviews much of the identification and control technology for structural control developed during this time. The technology was initially focused on space structure and weapon applications; however, recently the technology is also being directed toward applications in manufacturing and transportation. Much of this technology focused on multiple-input/multiple-output (MIMO) identification and control methodology because many of the applications require a coordinated control involving multiple disturbances and control objectives where multiple actuators and sensors are necessary for high performance. There have been many optimal robust control methods developed for the design of MIMO robust control laws; however, there appears to be a significant gap between the theoretical development and experimental evaluation of control and identification methods to address structural control applications. Many methods have been developed for MIMO identification and control of structures, such as the Eigensystem Realization Algorithm (ERA), Q-Markov Covariance Equivalent Realization (Q-Markov COVER) for identification; and, Linear Quadratic Gaussian (LQG), Frequency Weighted LQG and H-/ii-synthesis methods for control. Upon implementation, many of the identification and control methods have shown limitations such as the excitation of unmodelled dynamics and sensitivity to system parameter variations. As a result, research on methods which address these problems have been conducted.
This paper describes numerical simulations that were performed to study laminar flow through a square duct with a 90° bend. The purpose of this work was two fold. First, an improved understanding was desired of the flow physics involved in the generation of secondary vortical flows in three-dimensions. Second, adaptive gridding techniques for structured grids in three-dimensions were investigated for die purpose of determining their utility in low Reynolds number, incompressible flows. It was also of interest to provide additional validation of the commercial computer code CFD-ACE. Velocity predictions for both non-adaptive and adaptive grids are compared with experimental data. Flow visualization was used to examine the characteristics of the flow though the curved duct in order to better understand the viscous flow physics of this problem. Generally fair agreement with the experimental data was found, but questions were raised concerning the accuracy of the experimental data. The adaptive grids did not significantly improve the accuracy of the results beyond the non-adaptive grid solution with a similar number of points.
Since both FeS2 and MoS2 are optically opaque and have bandgaps in the near IR, photochemical applications of these materials are non-existent. It is however demonstrated in the study that nanosize FeS2 and MoS2 have bandgaps that can be adjusted to the visible and even UV region of the spectrum by control of the cluster size. Discussed are measurements of size, structure, optical absorbance and photoemission for these new materials. Also, briefly outlines are synthetic procedures and novel methods for chemical processing of these nanoclusters.
We report a real-time, two-dimensional light scattering study of the evolution of structure of a two component nonionic micelle system undergoing phase separation. The micelles act like molecular slug-a-beds whose domain growth is pathetically lathargic (i.e. slower than the cube root of time prediction for simple binary fluids). In fact, the growth kinetics can be empirically described as a stretched exponential approach to a pinned domain size. Although the kinetics are not yet understood, this anomalous behavior may be due to the ability of the spherical micelles to reorganize into more complex structures.
Proceedings of SPIE - The International Society for Optical Engineering
Parker, Gordon G.
A jib crane consists of a pendulum-like end line attached to a rotatable jib. Within this general category of cranes there exist devices with multiple degrees of freedom including variable load-line length and variable jib length. These cranes are commonly used for construction and transportation applications. Point-to-point payload maneuvers using jib cranes are performed so as not to excite the spherical pendulum modes of their cable and payload assemblies. Typically, these pendulum modes, although time-varying, exhibit low frequencies. The resulting maneuvers are therefore performed slowly, contributing to high construction and transportation costs. The crane considered here consists of a spherical pendulum attached to a rigid jib. The other end of the jib is attached to a direct drive motor of generating rotational motion. A general approach is presented for determining the open-loop trajectories for the jib rotation for accomplishing fixed-time, point-to-point, residual oscillation free, symmetric maneuvers. These residual oscillation free trajectories purposely excite the pendulum modes in such a way that at the end of the maneuver the oscillatory degrees of freedom are quiescent. Simulation results are presented with experimental verification.
First-principles density-functional calculations utilizing ab initio pseudopotentials and plane- wave expansions are used to determine lattice parameters, bulk moduli, and band structures for AlN, GaN, and InN. It is found that large numbers of plane waves are necessary to resolve the nitrogen 2p wave functions and that explicit treatment of the gallium 3d and indium 4d electrons is important for an accurate description of GaN and InN. Several properties of ternary zinc-blende alloys are determined including their bond-length and bond-angle relaxation and their energy-gap bowing parameters. The similarity of the calculated zinc- blende and wurtzite direct gaps also allows estimates to be made of the energy gap versus composition for wurtzite alloys.
A series of experiments was conducted to determine hydrogen combustion behavior under conditions of rapidly condensing steam caused by water sprays. Experiments were conducted in the Surtsey facility under conditions that were nearly prototypical of those that would be expected in a severe accident in the CE System 80+ containment. Mixtures were initially nonflammable owing to dilution by steam. The mixtures were ignited by thermal glow plugs when they became flammable after sufficient steam was removed by condensation caused by water sprays. No detonations or accelerated flame propagation was observed in the Surtsey facility. The combustion mode observed for prototypical mixtures was characterized by multiple deflagrations with relatively small pressure rises. The thermal glow plugs were effective in burning hydrogen safely by igniting the gases as the mixtures became marginally flammable.
This report identifies the key features noted as requirements in the diagnostic decision-making process of Single Photon Emission Computed Tomography (SPECT) cardiac imaging. The report discusses the critical issues that create the basic system framework for design of an automatic target recognizer (ATR) algorithm prototype to support diagnosis of coronary artery disease. Candidate feature discovery algorithms that may form the basis of future work include Adaptive Resonance Theory and Bayesian Decision Network. A framework for the practitioner-Human-System-Interface would include baseline patient history and demographic data; reference cardiac imagery history; and current overlay imagery to provide complementary information (i.e., coronary angiography, echocardiography, and SPECT images). The goal is to design a prototype that would represent a fused present and historical {open_quotes}whole{close_quotes} functional, structural, and physiologic cardiac patient model. This framework decision-assisting platform would be available to practitioner and student alike, with no {open_quotes}real-world{close_quotes} consequences.
This report describes the process used by Sandia National Laboratories, New Mexico to characterize weapon hardware for disposition. The report describes the following basic steps: (1) the drawing search process and primary hazard identification; (2) the development of Disassembly Procedures (DPs), including demilitarization and sanitization requirements; (3) the generation of a ``disposal tree``; (4) generating RCRA waste disposal information; and (5) documenting the information. Additional data gathered during the characterization process supporting hardware grouping and recycle efforts is also discussed.
Supercomputing `94, a high-performance computing and communications conference, was held November 14th through 18th, 1994 in Washington DC. For the past four years, Sandia National Laboratories has used this conference to showcase and focus its communications and networking endeavors. At the 1994 conference, Sandia built a Switched Multimegabit Data Service (SMDS) network running at 44.736 megabits per second linking its private SMDS network between its facilities in Albuquerque, New Mexico and Livermore, California to the convention center in Washington, D.C. For the show, the network was also extended from Sandia, New Mexico to Los Alamos National Laboratory and from Sandia, California to Lawrence Livermore National Laboratory. This paper documents and describes this network and how it was used at the conference.
The interstitial oxygen (O{sub i}) concentration in Czochralski silicon and the subsequent SiO{sub x} precipitation are important parameters for integrated circuit fabrication. Uncontrolled SiO{sub x} precipitation during processing can create detrimental mechanical and electrical effects that contribute to poor performance. An inability to consistently and accurately measure the initial O{sub i} concentration in heavily doped silicon has led to contradictory results regarding the effects of dopant type and concentration on SiO{sub x} precipitation. The authors have developed a software package for reliably determining and comparing O{sub i} in heavily doped silicon. The SiFTIR{copyright} code implements three independent oxygen analysis methods in a single integrated package. Routine oxygen measurements are desirable over a wide range of silicon resistivities, but there has been confusion concerning which of the three numerical methods is most suitable for the low resistivity portion of the continuum. A major strength of the software is an ability to rapidly produce results for all three methods using only a single Fourier Transform Infrared Spectroscopy (FTIR) spectrum as input. This ability to perform three analyses on a single data set allows a detailed comparison of the three methods across the entire range of resistivities in question. Integrated circuit manufacturers could use the enabling technology provided by SiFTIR{copyright} to monitor O{sub i} content. Early detection of O{sub i} using this diagnostic could be beneficial in controlling SiO{sub x} precipitation during integrated circuit processing.
FITTING is a Fortran subroutine that constructs a smooth, generalized four-parameter probability distribution model. It is fit to the first four statistical moments of the random variable X (i.e., average values of X, X{sup 2}, X{sup 3}, and X{sup 4}) which can be calculated from data using the associated subroutine CALMOM. The generalized model is produced from a cubic distortion of the parent model, calibrated to match the first four moments of the data. This four-moment matching is intended to provide models that are more faithful to the data in the upper tail of the distribution. Examples are shown for two specific cases.
Rountree, S.L.K.; Whitehurst, H.O.; Tomlin, E.H.; Restrepo, L.F.; White, J.
This report documents a study (Stage Right Operational Safety Analysis) that was performed to evaluate the effects of new Stage Right operations on the safety of Pantex personnel who perform the operations and maintain the equipment. The primary concern of the evaluation was for personnel safety during Stage Right operations, but operations equipment damage and degradation also were taken into account. This analysis evaluates safety of the work process in the staging of dismantled nuclear weapon pits within the modified Richmond magazines only. This Stage Right Process and Operational Safety Analysis includes the following processes: moving the pelletized drums from the pallet trailer to the pallet turner, staging of pallets and removal of pallets from the magazine, recovery from an incident in a magazine, setting up, opening, and closing a Zone 4 magazine, inventory of pelletized drums in the magazines, transporting pelletized drums from Zone 12 to Zone 4, and maintenance on the shielded lift truck that involves removal of the cab shielding. The analysis includes the following undesirable consequences: injury to personnel, breach of an AL-R8 container, drop of a loaded pallet, damage to equipment, and equipment unreliability.
The development of two new probabilistic accident consequence codes, MACCS and COSYMA, was completed in 1990. These codes estimate the risks presented by nuclear installations based on postulated frequencies and magnitudes of potential accidents. In 1991, the US Nuclear Regulatory Commission (NRC) and the Commission of the European Communities (CEC) began a joint uncertainty analysis of the two codes. The ultimate objective of the joint effort was to develop credible and traceable uncertainty distributions for the input variables of the codes. Expert elicitation was identified as the best technology available for developing a library of uncertainty distributions for the selected consequence parameters. The study was formulated jointly and was limited to the current code models and to physical quantities that could be measured in experiments. Experts developed their distributions independently. To validate the distributions generated for the wet deposition input variables, samples were taken from these distributions and propagated through the wet deposition code model. Resulting distributions closely replicated the aggregated elicited wet deposition distributions. To validate the distributions generated for the dispersion code input variables, samples from the distributions and propagated through the Gaussian plume model (GPM) implemented in the MACCS and COSYMA codes. Project teams from the NRC and CEC cooperated successfully to develop and implement a unified process for the elaboration of uncertainty distributions on consequence code input parameters. Formal expert judgment elicitation proved valuable for synthesizing the best available information. Distributions on measurable atmospheric dispersion and deposition parameters were successfully elicited from experts involved in the many phenomenological areas of consequence analysis. This volume is the first of a three-volume document describing the project.
IEEE International Symposium on Electronics & the Environment
Anderson, D.J.; Cranwell, R.M.; Iman, R.; Van Buren, P.D.
Environmental regulations are encouraging the development of new environmentally conscious manufacturing (ECM) processes. However, the quality and reliability of these processes and hardware produced must be understood prior to implementing these new technologies in factories. Furthermore, military hardware fabrication is governed by standards and specifications that frequently mandate the use of older, less environmentally friendly processes or materials, or prohibit the use of new ECM processes without advance military approval. Sandia National Laboratories, with industrial and military partners, have developed methodologies for evaluating and qualifying new ECM processes for military and commercial applications, and have piloted these methodologies in qualifying new, low-residue soldering technologies and materials.
Proceedings - IEEE International Conference on Robotics and Automation
Chen, Pang C.
To address the need for a fast path planner, we present a learning algorithm that improves path planning by using past experience to enhance future performance. The algorithm relies on an existing path planner to provide solutions to difficult tasks. From these solutions, an evolving sparse network of useful robot configurations is learned to support faster planning. More generally, the algorithm provides a framework in which a slow but effective planner may be improved both cost-wise and capability-wise by a faster but less effective planner coupled with experience. We analyze the algorithm by formalizing the concept of improvability and deriving conditions under which a planner can be improved within the framework. The analysis is based on two stochastic models, one pessimistic (on task complexity), the other randomized (on experience utility). Using these models, we derive quantitative bounds to predict the learning behavior. We use these estimation tools to characterize the situations in which the algorithm is useful and to provide bounds on the training time. In particular, we show how to predict the maximum achievable speedup. Additionally, our analysis techniques are elementary and should be useful for studying other types of probabilistic learning as well.
Barrier layers to limit percolation through cover systems are principal features of engineered, multi-component cover designs. Conventional barrier layer components developed for humid climates have limitations in dry climates. One alternative barrier layer is a capillary barrier, which consists of a fine-over-coarse soil arrangement. The capacity of capillary barriers to laterally divert downward moving water is the key to their success. Another alternative is a dry barrier, in which atmospheric air is circulated through a coarse layer within the cover to remove water vapor. Incorporating a coarse layer which stores water for subsequent removal by air flow reduces the requirements for the air flow velocity and increases the applicability of the dry barrier.
The development of software for use in high-consequence systems mandates rigorous (formal) processes, methods, and techniques to improve the safety characteristics of those systems. This paper provides a brief overview of current research and practices in high-consequence software, including applied design methods. Some of the practices that are discussed include: fault tree analysis, failure mode effects analysis, petri nets, both hardware and software interlocks, n-version programming, Independent Vulnerability Analyses, and watchdogs. Techniques that offer improvement in the dependability of software in high-consequence systems applications are identified and discussed. Limitations of these techniques are also explored. Research in formal methods, the cleanroom process, and reliability models are reviewed. In addition, current work by several leading researchers as well as approaches being used by leading practitioners are examined.
The five Solar Electric Generating Systems (SEGS) at Kramer Junction, California, now have nearly 30 years of cumulative operating experience. These 30 MW plants employ parabolic trough technology originally deployed by LUZ International in the late 1980`s and are now managed, operated and maintained by the Kramer Junction Company. In this paper, Sandia National Laboratories performed an analysis of the annual energy production from the five plants. Annual solar-to-electric conversion efficiencies are calculated and the major factors that influenced the results are presented. The generally good efficiencies are primarily attributed to the excellent equipment availabilities achieved at all plants.
This paper describe a system that was added to an existing satellite-borne telescope design for the purpose of compensating the boresight errors that had been observed in earlier flights of similar instruments. Those errors had been found to be caused by thermal distortion of the spaceframe. This retrofit design was subject to severe volume restrictions because it was fitted into an already tightly-packaged instrument envelope. It was found practical to improve the basic design by converting a redundant structure into a statically-determinate one. It was also possible to use portions of the mechanical actuation system to facilitate the position encoding needed for computer interfacing.
A sinkhole was first observed in May 1992 over the outer edge of the two-tiered former salt mine that was converted for oil storage by the US Strategic Petroleum Reserve (SPR). Results of diagnostic studies which included geophysical, geochemical, drilling, and hydrological methods suggest a direct connection exists between the surface collapse area and the underground mine. The connection was confirmed by correlative measurements of sediment slump rates, piezometric surface deflection, and brine influx rates into the mine. The dissolution of salt below the sinkhole that initiated the leak into the mine was likely caused by several confluent geologic processes, and exacerbated by mining-induced stresses that created fractures which severed as hydrologic flowpaths. Modeling studies of mine stresses show that years of tensional stresses may be required before cracking begins to occur, but once begun can continue to develop, and relieve the stress in that specific regime. The crack regime creates the avenue for incursion of groundwater, very slowly initially, but gradually enlarging as undersaturated groundwater dissolves salt on the sides of the crack. Mitigative measures include increasing the mine pressurization, slowing the dissolution by injecting brine into the sinkhole throat, and permeation grouting in hydrologic flowpaths.
The intent of the WIPP, being constructed in the bedded geologic salt deposits of Southeastern New Mexico, is to provide the technological basis for the safe disposal of radioactive Transuranic (TRU) wastes generated by the defense programs of the United States. In determining this technological basis, advanced reliability and structural analysis techniques are used to determine the probability of time-to-closure of a hypothetical underground shaft located in an argillaceous salt formation and filled with compacted crushed salt. Before being filled with crushed salt for sealing, the shaft provides access to an underground facility. Reliable closure of the shaft depends upon the sealing of the shaft through creep closure and recompaction of crushed backfill. Appropriate methods are demonstrated to calculate cumulative distribution functions of the closure based on laboratory determined random variable uncertainty in salt creep properties.
In a time when many companies are trying to find a way to do more with less, they are missing the ``solution`` that is right before their eyes. Rather than trying to decide on whether to reengineer or process improve, they should be focused on their most valuable resource: people. This paper discusses the elements of leadership and how it applies to all individuals in an organization. To get outstanding results from people, they need to begin by making leadership everybody`s business.
Tax loads and required revenues are estimated for current and future solar central receiver and gas-fired plants competing in the same market. An economic measure of tax equity is used to evaluate the equity of the tax loads under past and present tax codes. The same measure is used to devise a tax strategy which produces the following two types of equitable taxation: (1) the two plants carry nearly equal tax loads, and (2) local, state and federal governments receive the same distribution of revenues from the solar plant as from the gas-fired plant `Me results show that central receivers (and likely other capital-intensive technologies) carry higher tax loads compared to competing gasfired generation, that tax loads are highly correlated with competitiveness, and that equitable taxation is feasible within the boundaries of the study.
Recent Sandia support of the Solar Two project has included the analysis of optical performance issues related to heliostat field improvements. Two types of heliostats will be used for the Solar Two project: The 1818 original 38.4 m{sup 2} Martin Marietta Co. heliostats, and 108 new 95 m{sup 2} Lugo heliostats. Carrisa Plains mirror modules will be used to construct the Lugo heliostats and refurbish original heliostats. Baseline, clean reflectivity measurements of 0.90 and 0.94 are recomended for the original heliostat and the Carrisa Plains modules, respectively. Sandia`s Beam Characterization System provided beam quality information for representative configurations of both heliostats. This showed that the replacement of two facets with Carrisa Plains modules on an original heliostat led to a slight increase in spillage, but also increased beam power. As expected, the large beam of the Lugo heliostat showed poorer beam quality and significant spillage, but proved to be an economical addition of reflective area. The Carrisa Plains modules were found to be nominally flat, although the focal length changed slightly with temperature. An analysis of the canting options for both types of heliostats was performed. It was recommended the original heliostats be canted with an on-axis, lookback method, whereas a two-step method using first on-, then off-axis approaches was recommended for the Lugo heliostats. Finally, measurements performed at the Daggett site showed that despite the 1992 Landers earthquake, heliostat pedestal tilt and the associated tracking errors are expected to be within acceptable limits.
Reflux heat-pipe receivers have been identified as a desirable interface to couple a Stirling-cycle engine with a parabolic dish solar concentrator. The reflux receiver provides power nearly isothermally to the engine heater heads while decoupling the heater head design from the solar absorber surface design. The independent design of the receiver and engine heater head leads to higher system efficiency. Heat pipe reflux receivers have been demonstrated at approximately 65 kW{sub t} power throughput. Several 25 to 30-kW{sub e} Stirling-cycle engines are under development, and will soon be incorporated in commercial dish-Stirling systems. These engines will require reflux receivers with power throughput limits reaching 90-kW{sub t}. The extension of heat pipe technology from 60 kW{sub t} to 100 kW{sub t} is not trivial. Current heat pipe wick technology is pushed to its limits. It is necessary to develop and test advanced wick structure technologies to perform this task. Sandia has developed and begun testing a Bekaert Corporation felt metal wick structure fabricated by Porous Metal Products Inc. This wick is about 95% porous, and has liquid permeability a factor of 2 to 8 times higher than conventional technologies for a given maximum pore radius. The wick has been successfully demonstrated in a bench-scale heat pipe, and a full-scale on-sun receiver has been fabricated. This report details the wick design, characterization and installation into a heat pipe receiver, and the results of the bench-scale tests are presented. The wick performance is modeled, and the model results are compared to test results.
The ecological risk assessment process in its ideal form is an unbiased approach for assessing the probability of harm to the environment as a consequence of a given action. This information can then be combined with other societal values and biases in the management of such risks. However, as the process currently is understood, decision makers often are accused of manipulating information in order to generate decisions or achieve buy in from the public in support of a particular political agenda. A clear understanding of the nature of the risk management process can help define areas where information should be free from social or personal bias, and areas where values and judgments are critical. The authors do not propose to discuss the individual`s decision-making process, but rather to address the social process of risk communication and environmentally-related decision-making, identifying which parts of that process require bias-free, scientifically generated information about the consequences of various actions and which parts need an understanding of the social values which underlie the informed choices among those possible actions.
Mass transport properties are important in polycrystalline materials used as protective films. Traditionally, such properties have been studied by examining model polycrystalline structures, such as a regular array of straight grain boundaries. However, these models do not account for a number of features of real grain ensembles, including the grain size distribution and variations in grain shape. In this study, a finite difference scheme is developed to study transient and steady-state mass transport through realistic two dimensional polycrystalline microstructures. Comparisons with the transport properties of traditional model microstructures provide regimes of applicability of such models. The effects of microstructural parameters such as average grain size are examined.
As Sandia National Laboratories and the Physical and Chemical Sciences Center develop an increasingly diverse set of customers, research partners, and Cooperative Research and Development Agreements (CRADA`s) with industry, there is a need for providing more concise information describing the technical achievements and capabilities. This publication, Research Briefs, is designed to inform the present and potential partners in research and technology advancement. The research emphasizes semiconductor physics, electronic materials, surface physics and chemistry, plasma and chemical processing sciences, lasers and optics, vision science, ion-solid interactions and defect physics, and advanced materials physics. The specific programs pursued are driven by the research goals which are greatly influenced by interactions with the government and industrial customers.
The peak thermal power generated in microelectronics assemblies has risen from less than 1 W/cm{sup 2} in 1980 to greater than 40 W/cm{sup 2} today, due primarily to increasing densities at both the IC and packaging levels. The authors have demonstrated enhanced heat transfer in a prototype Si substrate with a backside micro heat channel structure. Unlike conventional micro heat pipes, these channels are biaxial with a greater capacity for fluid transfer. Thermal modeling and preliminary experiments have shown an equivalent increase in substrate thermal conductivity to over 500 W/m{center_dot}K, or a four times improvement. Optimization of the structure and alternative liquids will further increase the thermal conductivity of the micro heat channel substrate with the objective being polycrystalline diamond, or about 1,200 W/m{center_dot}K. The crucial design parameters for the micro heat channel system and the thermal characteristics of the system will be covered.