The Automated Sensor Tester (AST) is being developed by Sandia National Laboratories for the Department of Energy (DOE) to be a tool to aid in testing exterior intrusion detection sensors in a fixed site security system. This is accomplished by automatically performing a simulated intrusion test of the sensors installed in the Perimeter Intrusion Detection and Assessment System (PIDAS). During the test, a target is moved across the detection zone of the sensor, simulating a human moving through the detection zone. The first phase of this project concentrated on automatically testing the bi-static microwave exterior intrusion detection sensor in one sector of a PIDAS. This sensor was selected because it is commonly used, and the test target has been determined and is presently in use. The goal of the AST project is to provide consistent test results, automatic data logging, easier data reduction and reduced manpower to perform the DOE mandated and frequent intrusion detection sensor tests. The AST will help to determine that the intrusion sensor being tested is functional and has even and adequate detection along its entire detection zone. The AST consists of two vehicles and a data logger. The Mother Vehicle contains the processing and navigation capability and deployed and retrieved the Target Vehicle. The Target Vehicle provided the alarm stimulus. The Alarm Interface/Data Logger was connected to the intrusion sensors alarm signal and recorded the test results. This system will autonomously conduct a series of tests on an entire PIDAS sector. This paper describes the three elements of the AST system and their operation.
We are studying the boron nitride system using a pulsed excimer laser to ablate from hexagonal BN (cBN) targets to form cubic BN (cBN) films. We are depositing BN films on heated (25--800C) Si (100) surfaces and are using a broad-beam ion source operated with Ar and N{sub 2} source gases to produce BN films with a high percentage of sp{sup 3}-bonded cBN. In order to optimize growth and nucleation of cBN films, parametric studies of the growth parameters have been performed. The best films to date show >85% sp{sup 3}-bonded BN as determined from Fourier-transform infrared (FTIR) reflection spectroscopy. High resolution transmission electron microscopy (TEM) and selected area electron diffraction confirm the presence of cBN in these samples. The films are polycrystalline and show grain sizes up to 30--40 mn. We find from both the FTIR and TEM analyses that the cBN content in these films evolves with growth time. Initially, the films are deposited as hBN and the cBN nucleates on this hBN underlayer. Importantly, the position of the cBN IR phonon also changes with growth time. Initially this mode appears near 1130 cm{sup {minus}1} and the position decreases with growth time to a constant value of 1085 cm{sup {minus}1}. Since in bulk cBN this IR mode appears at 1065 cm{sup {minus}1}, a large compressive stress induced by the ion bombardment is suggested. In addition, we report on the variation in cBN percentage with temperature.
The physical properties of in-situ produced composites, such as the TEOS-polysiloxane based systems, are directly related to the complex interaction of structural features from the nano- to macro-scopic scales. The nature of these structural interactions are a key element in understanding and controlling mechanical properties in these systems. We believe that the smallest scale structures, in the nanometer range, correlate with properties such as the modulus while large-scale structures on the micron scale effect failure in these materials. This paper discusses techniques for analysis of structural features and interrelation of structural features over these wide ranges of size using small-angle light, x-ray and neutron scattering. Combination of data from different instruments allows for characterization of the interaction between these different size scale features.
In 1992 and 1993, numerous innovative and emerging technologies for characterizing metal and mixed waste contaminants and their migration beneath landfills in and environments were field tested at Sandia`s Chemical Waste Landfill. Many of these technologies are being evaluated as part of the Landfill Characterization System (LCS). The LCS emphasizes minimally intrusive technologies and downhole sensors that strive to be cheaper, better, safer and faster than conventional methods. Major aims of the LCS are to demonstrate, test and evaluate these technologies, and determine whether substantial cost saving over traditional baseline methods can be realized. To achieve these goals, the LCS uses an integrated systems approach that stresses the application of complementary and compatible technologies. Successful field demonstrations combined with favorable economics, will greatly assist the commercialization of these technologies to the private sector and to Environmental Restoration groups throughout the DOE Complex. In this paper, a technical and economic evaluation of selected technologies that comprise the LCS is presented. Because sampling and analysis is the most costly part of a characterization effort, the economic evaluation presented here focuses specifically on these activities. LCS technologies discussed include the ``Smart Sampling Methodology`` and two field screening analytical methods, stripping voltammetry and x-ray fluorescence.
Electroheological suspensions typically contain particles of approximately one {mu}m in diameter. Thus light-scattering offers a natural method of probing the microstructure of these suspensions. We report the development of an index matched single-scattering fluid, as well a slight-scattering studies of this fluid in both a quiescent and sheared regime. In the first case, the results are in agreement with a phenomenological theory of coarsening based on thermal fluctuations. In the second case, they agree with an ``independent droplet`` model of the suspensions structure under shear.
The success of technology transfer agreements depends not just on the technical work, but on how well the arrangements to protect and dispose of the intellectual properties that make up the technologies are handled. Pertinent issues that impact the protection and disposition of intellectual properties during the technology transfer process at Sandia National Laboratories, a multiprogram laboratory operated for the Department of Energy by the Martin Marietta Corporation, are discussed. Subjects addressed include the contracting mechanisms (including the Cooperative Research and Development Agreement [CRADA] and the Work-for-Others agreement), proprietary information, The Freedom of Information Act, patents and copyrights, the statement of work, Protected CRADA Information, licensing considerations, title to intellectual properties, march-in rights, and nondisclosure agreements.
An evaluation of the key elements affecting Direct Containment Heating (DCH) was performed for the Surry plant. This involved determining the dominant high pressure core damage sequences, the probability of proceeding to vessel breach at high pressure, the DCH loads, and the containment strength. Each of these factors was evaluated separately, and then the results were combined to give the overall threat from DCH. The maximum containment failure probability by DCH for Surry is 10{sup {minus}3} when considering four base DCH scenarios and using the two-cell equilibrium (TCE) model. However, higher contamination failure probabilities are estimated in sensitivity cases. When the depressurization and containment loads aspects are combined, the containment failure probability (conditional on station blackout sequence) is less than 19{sup {minus}2}. CONTAIN calculations were performed to provide insights regarding DCH phenomenological uncertainties and potential conservatisms in the TCE model. The CONTAIN calculations indicated that the TCE calculations were conservative for Surry and that the dominant factors were neglect of heat transfer to surroundings and complete combustion of hydrogen on DCH time scales.
A major obstacle to understanding of unsaturated fracture flow is the paucity of physical data on both fracture aperture structure and the effects of phase structure on permeability. An experimental procedure is developed for collecting detailed data on aperture and phase structure from a transparent analog fracture. Stable phase structures of varying complexity are creating within the horizontal analog fracture. Wetting phase permeability is measured under steady-state conditions. A process based model for wetting phase relative permeability is explored. Average distribution of the wetting phase is shown to provide insufficient information for modeling relative permeability; descriptive models must account for spatial structure of the phases.
Migration of hazardous contaminants within geologic settings depends on natural processes. Climatic fluctuations can affect the magnitudes and rates of many of these processes. In any long-term environmental evaluation of natural processes, responses to climatic change must be considered. Four generalized categories of natural responses to Quaternary climatic change are recognized for the Nevada Test Site (NTS) region of southwestern Nevada and adjacent California: (1) biologic, (2) geomorphic, (3) hydrologic (including surface and subsurface) and (4) pedologic/diagenetic. Specific examples that correspond to the four categories illustrate the broad range of complex natural processes the are affected by climatic change. These responses dictate the potential effects of climatic change on contaminant transport, effects that are being examined by existing and planned environmental-restoration and waste-management programs within the region. Regulatory requirements for many of these programs include long-term (>10,000-year) waste isolation because of radiologic components. The purpose here is not to be exhaustive in documenting all known natural responses to climatic change in the NTS region, but rather to give a flavor of the scope of interdisciplinary and interrelated fields of Quaternary science that must be considered in evaluating the possible effects of climatic change on long-term environmental programs.
The variance of an estimate of an autospectral density (power spectral density) obtained using Welch`s method is examined This error is examined in terms of a normalized error measure. Particular attention is given to the temporal windows and overlap processing.
Shock physics codes for armor analysis and the computers used to run them have improved dramatically over the last five years. Improved algorithms and material models allow accurate and efficient modeling of conventional armors. Desktop workstations routinely perform production two-dimensional calculations and massively parallel computers perform three-dimensional calculations. New developments in codes and computers promise improved accuracy, increased capabilities and faster simulation. This paper describes the current state of armor analysis codes and computers. Armor analysis code features fall into one of five categories: mesh, solution algorithm, material model, heuristic or computer. This paper discusses the current state of each of these categories and discusses the additional work needed.
The X Window System was originally developed in 1984 at Massachusetts Institute of Technology. It provides client-server computing functionality and also facilitates the establishment of a distributed computing environment. Since its inception the X Window System has undergone many enhancements. Despite these enhancements there will always be a functionality desired in the standard released version of X that is not supported or commercially or academically available. The developers of the X Window System have designed it in such a way that it is possible to add functionality that is not included in the standard release. This is called an extension. Extensions are one method used to develop a customized version of the X Window System to support a specialized application. This report presents the mechanics of adding an extension and examines a particular extension that was developed at Sandia National Laboratories to support data compression in X Windows which was one aspect of the Desktop Video and Collaborative Engineering Laboratory Directed Research and Development (LDRD).
This research investigates the relationship between execution discipline and performance. The hypothesis has two parts: 1. Different execution disciplines exhibit different performance for different computations, and 2. These differences can be effectively predicted by heuristics. A machine model is developed that can vary its execution discipline. That is, the model can execute a given program using either the control-driven, data-driven or demand-driven execution discipline. This model is referred to as a ``variable-execution-discipline`` machine. The instruction set for the model is the Program Dependence Web (PDW). The first part of the hypothesis will be tested by simulating the execution of the machine model on a suite of computations, based on the Livermore Fortran Kernel (LFK) Test (a.k.a. the Livermore Loops), using all three execution disciplines. Heuristics are developed to predict relative performance. These heuristics predict (a) the execution time under each discipline for one iteration of each loop and (b) the number of iterations taken by that loop; then the heuristics use those predictions to develop a prediction for the execution of the entire loop. Similar calculations are performed for branch statements. The second part of the hypothesis will be tested by comparing the results of the simulated execution with the predictions produced by the heuristics. If the hypothesis is supported, then the door is open for the development of machines that can vary execution discipline to increase performance.
This paper describes a collision avoidance system using Whole Arm Proximity (WHAP) sensors on an articulated robot arm. The capacitance-based sensors generate electric fields which completely encompass the robot arm and detect obstacles as they approach from any direction. The robot is moved through the workspace using a velocity command generated either by an operator through a force-sensing input device or a preprogrammed sequence of motions. The directional obstacle information gathered by the WHAP sensors is then used in a matrix column maximization algorithm that automatically selects the sensor closest to an obstacle during each robot controller cycle. The distance from this sensor to the obstacle is used to reduce the component of the command input velocity along the normal axis of the sensor, allowing graceful perturbation of the velocity command to prevent a collision. By scaling only the component of the velocity vector in the direction of the nearest obstacle, the control system restricts motion in the direction of an obstacle while permitting unconstrained motion in other directions. The actual robot joint positions and the WHAP sensor readings are communicated to an operator interface consisting of a graphical model of the Puma robot and its environment. Circles are placed on the graphical robot surface at positions corresponding to the locations of the WHAP sensor. As the individual sensors detect obstacles, the associated circles change color, providing the operator with visual feedback as to the location and relative size of the obstacle. At the same time, the graphical robot position is updated to reflect the actual state of the robot. This information, coupled with the selective constraints imposed by the WHAP control system, permit the operator to plan alternative paths around unmodeled, but sensed, obstacles.
This video cassette and its corresponding script describe efforts at Sandia Laboratories to develop surveillance equipment to include geophone sensors, point sensors, line sensors, and video surveillance cameras.
Conference Record of the IEEE Photovoltaic Specialists Conference
Stevens, J.; Kratochvil, J.; Harrington, S.
Four photovoltaic-powered lighting systems were installed in a National Forest Service campground in June of 1991. These systems have identical arrays, loads and charge controllers. The only difference was in the rated capacity of the battery bank for each system. The battery banks all use the same basic battery as a building block with four systems utilizing either one battery, two batteries, three batteries or four batteries. The purpose of the experiment is to examine the effect of the various battery sizes on the ability of the system to charge the battery, energy available to the load, and battery lifetime. Results show an important trend in system performance concerning the impact of charge controllers on the relation between array size and battery size which results in an inability to achieve the days of battery storage originally designed for.
During 1989-90, a refluxing liquid-metal pool-boiler solar receiver designed for dish/Stirling application at 75 kWt throughput was successfully demonstrated at Sandia National Laboratories. Significant features of this receiver included (1) boiling sodium as the heat transfer medium and (2) electric-discharge-machined (EDM) cavities as artificial nucleation sites to stabilize boiling. Following this first demonstration, a second-generation pool-boiler receiver that brings the concept closer to commercialization has been designed, constructed, and successfully tested. For long life, the new receiver is built from Haynes Alloy 230. For increased safety factors against film boiling and flooding, the absorber area and vapor-flow passages have been enlarged. To eliminate the need for trace heating, sodium has been replaced by the sodium-potassium alloy NaK-78. To reduce manufacturing costs, the receiver has a powdered-metal coating instead of EDM cavities for stabilization of boiling. To control incipient-boiling superheats, especially during hot restarts, it contains a small amount of xenon. In this paper, we present the receiver design and report the results of on-sun tests using a nominal 75 kWt test-bed concentrator to characterize boiling stability, hot-restart behavior, and thermal efficiency at temperatures up to 750°C. We also report briefly on late results from an advanced-concepts pool-boiler receiver.
The article presents the use of Monte Carlo simulations or incoherent scattering model to calculate profiles from precipitates embedded at different depths in thin specimens and then compared the simulations with experimental data measured from embedded particles. Incoherent scattering models is believed to be the best simulation for spatial resolution for x ray microanalysis in the AEM.
The development of UHF spark-switched L-C oscillators is described. L-C oscillators with center frequencies of 450 to 800 MHz were constructed. Q of the oscillators increased when a resonant antenna or antenna-reflector combination was added. Prototypes with simple fat-dipole antennas and small parabolic reflectors radiated normalized electric field strengths of 60 kV/m. The L-C oscillator, fat dipole, and small parabolic cylinder reflector were mounted in a way that will maximize the radiated power.
American Society of Mechanical Engineers, Pressure Vessels and Piping Division (Publication) PVP
Priddy, G.T.
Codes and standards have served remarkably well in reducing both the frequency and consequences of pressure vessel and piping system failures. Past successful uses of safety standards show that safety can indeed be designed into potentially hazardous systems. Operational maintenance and inspection programs can also ensure and perpetuate design and manufactured reliability. However, as more advanced and challenging applications with high pressure systems and potentially hazardous operations are encountered we need to sharpen our technology, estimate reliability, quantify consequences, and manage risks with cost-effective process. Practical systems are constructed of several components, and design standards are not always available for every component. A variable level of safety is, therefore, admitted within a system and some assessment of the overall safety is desired. Additionally, when potential personnel safety consequences are large but isolated, secondary protective steps should be considered such as barricading, protective enclosures, or remote operation. This paper discusses rationale and activates that are based on probabilistic risk assessment (PRA) methods. While general application of PRA is not advocated at this time, certain derivative parts are suggested for use in closed-loop, risk management activities. Risk management process developments such as development of probabilistic data for threats to system safety and system response, component design requirements, system safety rules, distributed safety goals and technical derivations of numerical criteria are encouraged. Suggested activities are proposed as topics for future High Pressure Technology Development Activities.
The JPL Micro-Precision Interferometer (MPI) is a testbed for studying the use of control-structure interaction technology in the design of space-based interferometers. A layered control architecture will be employed to regulate the interferometer optical system to tolerances in the nanometer range. This paper summarizes coordinated test and analysis efforts aimed at producing such a model for the MPI structure. Pretest analysis, modal testing and test-analysis reconciliation results are summarized for a series of tests at both the component and full system levels.
Demonstrated in this study is the phase identification through a combination of backscattered electron Kikuchi patterns (BEKP) and energy dispersive x-ray spectrometry (EDS) by the identification of crystals present on ruthenium oxide thin films on Si. The crystals were identified as RuO2, a tetragonal phase. The charge coupled device (CCD)-based detector is also briefly described. The ability of the CCD-based detector to collect high quality patterns without the use of photographic emulsions enables on-line analysis of the BEKP's.
Hazardous operations which in the past have been completed by technicians are under increased scrutiny due to high costs and low productivity associated with providing protective clothing and environments. As a result, remote systems are needed to accomplish many hazardous materials handling tasks such as the clean up of waste sites in which the exposure of personnel to radiation, chemical, explosive, and other hazardous constituents is unacceptable. Traditional remote operations have proven to have very low productivity when compared with unencumbered humans. Computer models augmented by sensing and structured, modular computing environments are proving to be effective in automating many unstructured hazardous tasks.
Photoconductive Semiconductor Switches (PCSS) are being used in, or tested for, many different pulsed power applications as diverse as ultrawideband (UWB) transmitters and high current pulsers. Some aspects of the switches that are relevant to most of the applications are: switch lifetime (longevity), switch opening time (related to the lifetime of carriers in the semiconductor), switching jitter, and the required laser energy. This paper will emphasize the results that we have obtained with Si switches for UWB applications. These include: measurement of switch longevity (a total of 80 Coulombs or 40 C/cm for a 2 cm wide switch and 18.4 Coulombs or 73 Coulombs/cm for a 0.25 cm wide switch), switching at high repetition rates (up to 540 Hz), measurement of carrier lifetime decay rates (a fast one of a few μs, and a slow one of about 330 μs), and measurements on the effect of neutron irradiation on carrier lifetimes. The total charge switched seems to be the highest ever reported for a PCSS. We have used these Si switches in a variety of circuits to produce: a monocycle with a period of about 10 ns corresponding to a center frequency of about 84 MHz, and ringing (many pulse) waveforms with periods of about 1 ns and 7.5 ns corresponding to center frequencies of 770 MHz and 133 MHz. We will also discuss recent studies on the switching properties of GaP.