Energy security is a fundamental part of a country`s national security. Access to affordable, environmentally sustainable energy is a stabilizing force and is in the world community`s best interest. The current global energy situation however is not sustainable and has many complicating factors. The primary goal for government energy policy should be to provide stability and predictability to the market. This paper differentiates between short-term and long-term issues and argues that although the options for addressing the short-term issues are limited, there is an opportunity to alter the course of long-term energy stability and predictability through research and technology development. While reliance on foreign oil in the short term can be consistent with short-term energy security goals, there are sufficient long-term issues associated with fossil fuel use, in particular, as to require a long-term role for the federal government in funding research. The longer term issues fall into three categories. First, oil resources are finite and there is increasing world dependence on a limited number of suppliers. Second, the world demographics are changing dramatically and the emerging industrialized nations will have greater supply needs. Third, increasing attention to the environmental impacts of energy production and use will limit supply options. In addition to this global view, some of the changes occurring in the US domestic energy picture have implications that will encourage energy efficiency and new technology development. The paper concludes that technological innovation has provided a great benefit in the past and can continue to do so in the future if it is both channels toward a sustainable energy future and if it is committed to, and invested in, as a deliberate long-term policy option.
Microfabricated electro-optical-mechanical systems are expected to play an important role in future biomedical, biochemical and environmental technologies. Semiconductor photonic materials and devices are attractive components of such systems because of their ability to generate, transmit, modulate, and detect light. In this paper the authors report investigations of light-emitting semiconductor/glass microcavities filled with simple fluids. They examine surface tension for transporting liquids into the intracavity space and study the influence of the liquid on the spectral emission of the microcavity.
Advanced device technologies such as Vertical Cavity Surface-Emitting Lasers (VCSELs) and diffractive micro lenses can be obtained with novel packaging techniques to allow low-power interconnection of parallel optical signals. These interconnections can be realized directly on circuit boards, in a multi-chip module format, or in packages that emulate electrical connectors. For applications such as stacking of Multi-Chip Module (MCM) layers, the links may be realized in bi-directional form using integrated diffractive microlenses. In the stacked MCM design, consumed electrical power is minimized by use of a relatively high laser output from high efficiency VCSELs, and a receiver design that is optimized for low power, at the expense of dynamic range. Within certain constraints, the design may be extended to other forms such as board-level interconnects.
One of the principal applications of monolithically integrated micromechanical/microelectronic systems has been accelerometers for automotive applications. As integrated MEMS/CMOS technologies such as those developed by U.C. Berkeley, Analog Devices, and Sandia National Laboratories mature, additional systems for more sensitive inertial measurements will enter the commercial marketplace. In this paper, the authors will examine key technology design rules which impact the performance and cost of inertial measurement devices manufactured in integrated MEMS/CMOS technologies. These design parameters include: (1) minimum MEMS feature size, (2) minimum CMOS feature size, (3) maximum MEMS linear dimension, (4) number of mechanical MEMS layers, (5) MEMS/CMOS spacing. In particular, the embedded approach to integration developed at Sandia will be examined in the context of these technology features. Presently, this technology offers MEMS feature sizes as small as 1 {micro}m, CMOS critical dimensions of 1.25 {micro}m, MEMS linear dimensions of 1,000 {micro}m, a single mechanical level of polysilicon, and a 100 {micro}m space between MEMS and CMOS. This is applicable to modern precision guided munitions.
An experimental signature for detecting spontaneous lateral composition modulation in a (InAs){sub n}/(GaAs){sub n} short period superlattice on a InP substrate based on magnetoexciton spectroscopy is presented. The authors find by aligning the magnetic field in three crystallographic directions, one parallel to and the other two perpendicular to the composition modulation direction, that the magnetoexciton shifts are anisotropic and are a good indicator for the presence of composition modulation.
MACCS2 represents a major enhancement of the capabilities of its predecessor MACCS, the MELCOR Accident Consequence Code System. MACCS, released in 1987, was developed to estimate the potential impacts to the surrounding public of severe accidents at nuclear power plants. The principal phenomena considered in MACCS/MACCS2 are atmospheric transport and deposition under time-variant meteorology, short-term and long-term mitigative actions and exposure pathways, deterministic and stochastic health effects, and economic costs. MACCS2 was developed as a general-purpose analytical tool applicable to diverse reactor and nonreactor facilities. The MACCS2 package includes three primary enhancements: (1) a more flexible emergency response model, (2) an expanded library of radionuclides, and (3) a semidynamic food-chain model. In addition, errors that had been identified in MACCS version1.5.11.1 were corrected, including an error that prevented the code from providing intermediate-phase results. MACCS2 version 1.10 beta test was released to the beta-test group in May, 1995. In addition, the University of New Mexico (UNM) has completed an independent verification study of the code package. Since the beta-test release of MACCS2 version 1.10, a number of minor errors have been identified and corrected, and a number of enhancements have been added to the code package. The code enhancements added since the beta-test release of version 1.10 include: (1) an option to allow the user to input the {sigma}{sub y} and {sigma}{sub z} plume expansion parameters in a table-lookup form for incremental downwind distances, (2) an option to define different initial dimensions for up to four segments of a release, (3) an enhancement to the COMIDA2 food-chain model preprocessor to allow the user to supply externally calculated tables of tritium food-chain dose per unit deposition on farmland to support analyses of tritium releases, and (4) the capability to calculate direction-dependent doses.
The constraints on assembly plans vary depending on the product, assembly facility, assembly volume, and many other factors. This paper describes the principles and implementation of a framework that supports a wide variety of user-specified constraints for interactive assembly planning. Constraints from many sources can be expressed on a sequencing level, specifying orders and conditions on part mating operations in a number of ways. All constraints are implemented as filters that either accept or reject assembly operations proposed by the planner. For efficiency, some constraints are supplemented with special-purpose modifications to the planner`s algorithms. Replanning is fast enough to enable a natural plan-view-constrain-replan cycle that aids in constraint discovery and documentation. We describe an implementation of the framework in a computer-aided assembly planning system and experiments applying the system to several complex assemblies. 12 refs., 2 figs., 3 tabs.
We demonstrate that computer-generated diffractive optical elements can be used to synthesize the infrared spectra of real compounds. In particular, we describe a modified phase-retrieval algorithm that we have used to design diffractive elements of this type and we present experimental results for a diffractive optic which is capable of synthesizing the infrared spectrum of HF between 3600 cm{sup -1} and 4300 cm{sup -1}. The reflection-mode diffractive optic consists of 4096 lines, each 4.5 {mu}m wide, at 16 discrete depths relative to the substrate (from 0 to 1.2 {mu}m), and was fabricated on a silicon wafer using anisotropic reactive ion-beam etching in a four-mask-level process. We propose the use of such elements to replace reference cells in a new type of correlation spectroscopy that we call {open_quotes}holographic correlation spectroscopy.{close_quotes} Storage of a large number of diffractive elements, each producing a synthetic spectrum corresponding to a different target compound, in compact disk-like format, will allow a spectrometer of this type to rapidly determine the composition of unknown samples. Further, this approach can be used to perform correlation-based measurements of hazardous or transient species, for which conventional correlation spectroscopy is impractical.
A system for automatic tool path generation was developed at Sandia National Laboratories for finish machining operations. The system consists of a commercially available 5-axis milling machine controlled by Sandia developed software. This system was used to remove overspray on cast turbine blades. A laser-based, structured-light sensor, mounted on a tool holder, is used to collect 3D data points around the surface of the turbine blade. Using the digitized model of the blade, a tool path is generated which will drive a 0.375 inch diameter CBN grinding pin around the tip of the blade. A fuzzified digital filter was developed to properly eliminate false sensor readings caused by burrs, holes and overspray. The digital filter was found to successfully generate the correct tool path for a blade with intentionally scanned holes and defects. The fuzzified filter improved the computation efficiency by a factor of 25. For application to general parts, an adaptive scanning algorithm was developed and presented with simulation results. A right pyramid and an ellipsoid were scanned successfully with the adaptive algorithm.
Although the Cold War has ended, the world has not become more peaceful. Without the stability provided by an international system dominated by two super-powers, local conflicts are more likely to escalate. Agreements to counter destabilizing pressures in regional conflicts can benefit from the use of cooperative monitoring. Cooperative monitoring is the collecting, analyzing, and sharing of information among parties to an agreement. Ground sensor technologies can contribute to the collection of relevant information. If implemented with consideration for local conditions, cooperative monitoring can build confidence, strengthen existing agreements, and set the stage for continued progress. This presentation describes two examples: the Israeli-Egyptian Sinai agreements of the 1970s and a conceptual example for the contemporary Korean Peninsula. The Sinai was a precedent for the successful use of UGS within the context of cooperative monitoring. The Korean Peninsula is the world`s largest military confrontation. Future confidence building measures that address the security needs of both countries could decrease the danger of conflict and help create an environment for a peace agreement.
A Sunstove Organization`s Sunstove was tested at Sandia`s Solar Thermal Test Facility. It was instrumented with five type K thermocouples to determine warm-up rates when empty and when a pot containing two liters of water was placed inside. It reached inside air temperatures above 115{degrees}C (240{degrees}F). It heated two liters of water from room temperature to 80{degrees}C (175{degrees}F) in about two hours. Observations were made on the cooling and reheating rates during a cloud passage. The adverse effects of wind on the operation of the solar oven were also noted.
A Burns-Milwaukee Sun Oven was tested at Sandia`s Solar Thermal Test Facility. It was instrumented with five type K thermocouples to determine warm-up rates when empty and when a pot containing two liters of water was placed inside. It reached inside air temperatures above 160{degrees}C (320{degrees}F). It heated two liters of water from room temperatures to 80{degrees}C, (175{degrees}F), in 75 minutes. Observations were also made on the cooling and reheating rates during a cloud passage. The adverse effects of wind on operation of the solar oven was also noted.
The Molina Member of the Wasatch Formation produces natural gas from several fields along the Colorado River in the Piceance Basin, northwestern Colorado. The Molina Member is a distinctive sandstone that was deposited in a unique fluvial environment of shallow-water floods. This is recorded by the dominance of plane-parallel bedding in many of the sandstones. The Molina sandstones crop out on the western edge of the basin, and have been projected into the subsurface and across the basin to correlate with thinner sandy units of the Wasatch Formation at the eastern side of the basin. Detailed study, however, has shown that the sedimentary characteristics of the type-section Molina sandstones are incompatible with a model in which the eastern sandstones are its distal facies equivalent. Rather, the eastern sandstones represent separate and unrelated sedimentary systems that prograded into the basin from nearby source-area highlands. Therefore, only the subsurface {open_quotes}Molina{close_quotes} reservoirs that are in close proximity to the western edge of the basin are continuous with the type-section sandstones. Reservoirs in the Grand Valley and Rulison gas fields were deposited in separate fluvial systems. These sandstones contain more typical fluvial sedimentary structures such as crossbeds and lateral accretion surfaces. Natural fractures play an important role in enhancing the conductivity and permeability of the Molina and related sandstones of the Wasatch Formation.
An automated system is being developed for handling large payloads of radioactive nuclear materials in an analytical laboratory. The automation system performs unpacking and repacking of payloads from shipping and storage containers, and delivery of the payloads to the stations in the laboratory. The system uses machine vision and force/torque sensing to provide sensor-based control of the automation system in order to enhance system safety, flexibility, and robustness, and achieve easy remote operation. The automation system also controls the operation of the laboratory measurement systems and the coordination of them with the robotic system. Particular attention has been given to system design features and analytical methods that provide an enhanced level of operational safety. Independent mechanical gripper interlock and tool release mechanisms were designed to prevent payload mishandling. An extensive Failure Modes and Effects Analysis of the automation system was developed as a safety design analysis tool.
Algorithms have been developed allowing operation of robotic systems under damaged conditions. Specific areas addressed were optimal sensor location, adaptive nonlinear control, fault-tolerant robot design, and dynamic path-planning. A seven-degree-of-freedom, hydraulic manipulator, with fault-tolerant joint design was also constructed and tested. This report completes this project which was funded under the Laboratory Directed Research and Development program.
The design of an effective physical protection system includes the determination of physical protection system objectives, initial design of a physical protection system, design evaluation, and probably a redesign or refinement. To develop the objectives, the designer must begin by gathering information about facility operation and conditions, such as a comprehensive description of the facility, operating conditions, and the physical protection requirements. The designer then needs to define the threat. This involves considering factors about potential adversaries: class of adversary, adversary`s capabilities, and range of adversary`s tactics. Next, the designer should identify targets. Determination of whether or not the materials being protected are attractive targets is based mainly on the ease or difficulty of acquisition and desirability of the material. The designer now knows the objectives of the physical protection system, that is, {open_quotes}what to protect against whom.{close_quotes} The next step is to design the system by determining how best to combine such elements as fences, vaults, sensors and assessment devices, entry control elements, procedures, communication devices, and protective forces personnel to meet the objectives of the system. Once a physical protection system is designed, it must be analyzed and evaluated to ensure it meets the physical protection objectives. Evaluation must allow for features working together to ensure protection rather than regarding each feature separately. Due to the complexity of the protection systems, an evaluation usually requires modeling techniques. If any vulnerabilities are found, the initial system must be redesigned to correct the vulnerabilities and a reevaluation conducted. This paper reviews the physical protection system design and methodology mentioned above. Examples of the steps required and a brief introduction to some of the technologies used in modem physical protections system are given.
Applications for high current (> 1 kA) ion beams are increasing. They include hardening of material surfaces, transmutation of radioactive waste, cancer treatment, and possibly driving fusion reactions to create energy. The space-charge of ions limits the current that can be accelerated in a conventional ion linear accelerator (linac). Furthermore, the accelerating electric field must be kept low enough to avoid the generation and acceleration of counter-streaming electrons. These limitations have resulted in ion accelerator designs that employ long beam lines and would be expensive to build. Space-charge neutralization and magnetic insulation of the acceleration gaps could substantially reduce these two limitations, but at the expense of increasing the complexity of the beam physics. We present theory and experiments to determine the degree of charge-neutralization that can be achieved in various environments found in ion accelerators. Our results suggest that, for high current applications, space-charge neutralization could be used to improve on the conventional ion accelerator technology. There are two basic magnetic field geometries that can be used to insulate the accelerating gaps, a radial field or a cusp field. We will present studies related to both of these geometries. We shall also present numerical simulations of {open_quotes}multicusp{close_quotes} accelerator that would deliver potassium ions at 400 MeV with a total beam power of approximately 40 TW. Such an accelerator could be used to drive fusion.
The Downhole Dynamometer Database is a compilation of test data collected with a set of five downhole tools built by Albert Engineering under contract to Sandia National Laboratories. The downhole dynamometer tools are memory tools deployed in the sucker rod string with sensors to measure pressure, temperature, load, and acceleration. The acceleration data is processed to yield position, so that a load vs. position dynagraph can be generated using data collected downhole. With five tools in the hole at one time, all measured data and computed dynagraphs from five different positions in the rod string are available. The purpose of the Database is to provide industry with a complete and high quality measurement of downhole sucker rod pumping dynamics. To facilitate use of the database, Sandia has developed a Microsoft Windows-based interface that functions as a visualizer and browser to the more than 40 MBytes of data. The interface also includes a data export feature to allow users to extract data from the database for use in their own programs. Following a brief description of the downhole dynamometer tools, data collection program, and database content, this paper will illustrate a few of the interesting and unique insights gained from the downhole data.
Liquid metal reflux receivers (LMRRs) have been designed to serve as the interface between the solar concentrator dish and the Stirling engine of a dish Stirling power system. Such a receiver has undergone performance testing at Sandia National Laboratory to determine cold- and hot-start characteristics, component temperatures, throughput power, and thermal efficiency, for various times of day and year. Performance modeling will play an important role in the future commercialization of these systems since it will be necessary to predict overall energy production for potential installation sites based on available meteorological data. As a supplement to numerical thermal modeling, artificial neural networks (ANNs) have been investigated for their effectiveness in predicting long-term energy production of a LMRR. Two types of data were used to train ANNs, actual on-sun test data, and ersatz data. ANNs were trained on both the raw on-sun test data and on pre-formatted versions of the data to determine if pre-formatting of the input data would improve network training efficiency and predictive abilities. Usable on-sun test data were available for only a few days of performance testing. Therefore, a set of year-long ersatz data was generated using a transient numerical model driven by one-minute meteorological data from the Solar Energy Meteorological Research and Training Sites (SEMRTS) data base for Davis, CA. The ersatz data were used to train ANNs based on warm-month data, cool-month data, and year-long data to investigate the impact of using seasonal test data on long-term predictive capabilities. The findings indicated that a network trained on data from a limited time span could successfully predict annual energy output of a liquid metal receiver.
A non-conventional type of heating system is being tested at Sandia National Laboratories for solar thermal power tower applications. In this system, called impedance heating, electric current flows directly through the pipe to maintain the desired temperature. The pipe becomes the resistor where the heat is generated. Impedance heating has many advantages over previously used mineral insulated (MI) heat trace. An impedance heating system should be much more reliable than heat trace cable since delicate junctions and cabling are not used and the main component, a transformer, is inherently reliable. A big advantage of impedance heating is the system can be sized to rapidly heat up the piping to provide rapid response times necessary in cyclic power plants such as solar power towers. In this paper, experimental results from testing an impedance heating system are compared to MI heat trace. The authors found impedance heating was able to heat piping rapidly and effectively. There were not significant stray currents and impedance heating did not affect instrumentation.
In this work, the authors have applied mold micromachining and standard photolithographic techniques to the fabrication of parts integrated with 0.4 micron pitch diffraction gratings. In principle, the approach should be scaleable to considerably finer pitches. They have achieved this by relying on the thickness of deposited or grown films, instead of photolithography, to determine the grating pitch. The gratings can be made to extend over large areas and the entire process is compatible with batch processing. Literally thousands of parts can be batch fabricated from a single lot of six inch wafers. In the first stage of the process they fabricate a planarized silicon dioxide pad over which the silicon nitride wave guide runs. The grating is formed by first patterning and etching single crystalline silicon to form a series of trenches with well defined pitch. The silicon bounding the trenches is then thinned by thermal oxidation followed by stripping of the silicon dioxide. The trenches are filled by a combination of polysilicon depositions and thermal oxidations. Chemical mechanical polishing (CMP) is used to polish back these structures resulting in a series of alternating 2000 {angstrom} wide lines of silicon and silicon dioxide. The thickness of the lines is determined by the oxidation time and the polysilicon deposition thickness. The silicon lines are selectively recessed by anisotropic reactive ion etching, thus forming the mold for the grating. The mold is filled with low stress silicon nitride deposited by chemical vapor deposition. A wave guide is then patterned into the silicon nitride and the mold is locally removed by a combination of deep silicon trench etching and wet KOH etching. This results in a suspended diffraction grating/membrane over the KOH generated pit.
To characterize particle size/magnetic property relationships, 9 to 50 nm in diameter barium hexaferrite, BaFe{sub 12}O{sub 19} (BHF), particles were prepared using a new synthesis route. By replacing the conventional 50 to 100 nm particles of goethite with nanocrystalline goethite produced via the microwave anneal method of Knight and Sylva, nanocrystalline BHF was synthesized using the hydrothermal method. Evolution of particle size and morphology with respect to concentration and heat treatment time is reported. Hysteresis properties, including coercivity (0.2--1.0 kOe), magnetization saturation (0.1--33.4 emu/g), and magnetization remanence (0.004--22.5 emu/g) are discussed as a function of particle size. The magnetization saturation and remanence of the 7 nm particles is nearly zero, suggesting the superparamagnetic threshold size for BHF is around this size. In addition, the equilibrium morphology of BHF crystals was calculated to be truncated hexagonal prisms which was verified by experiment, and the isoelectric point, pH of 4.1, was measured for 18 nm BHF particles.
Electrokinetic remediation is generally an in situ method using direct current electric potentials to move ionic contaminants and/or water to collection electrodes. The method has been extensively studied for application in saturated clayey soils. Over the past few years, an electrokinetic extraction method specific for sandy, unsaturated soils has been developed and patented by Sandia National Laboratories. A RCRA RD&D permitted demonstration of this technology for the in situ removal of chromate contamination from unsaturated soils in a former chromic acid disposal pit was operated during the summer and fall of 1996. This large scale field test represents the first use of electrokinetics for the removal of heavy metal contamination from unsaturated soils in the United States and is part of the US EPA Superfund Innovative Technology Evaluation (SITE) Program. Guidelines for characterizing a site for electrokinetic remediation are lacking, especially for applications in unsaturated soil. The transference number of an ion is the fraction of the current carried by that ion in an electric field and represents the best measure of contaminant removal efficiency in most electrokinetic remediation processes. In this paper we compare the transference number of chromate initially present in the contaminated unsaturated soil, with the transference number in the electrokinetic process effluent to demonstrate the utility of evaluating this parameter.
For almost four years, the U.S. Department of Energy (DOE) through its Federal Facility Compliance Act Disposal Workgroup has been working with state regulators and governors` offices to develop an acceptable configuration for disposal of its mixed low-level waste (MLLW). These interactions have resulted in screening the universe of potential disposal sites from 49 to 15 and conducting ``performance evaluations`` for those fifteen sites to estimate their technical capabilities for disposal of MLLW. In the residuals analysis project, we estimated the volume of DOE`s MLLW that will require disposal after treatment and the concentrations of radionuclides in the treated waste. We then compared the radionuclide concentrations with the disposal limits determined in the performance evaluation project for each of the fifteen sites. The results are a scoping-level estimate of the required volumetric capacity for MLLW disposal and the identification of waste streams that may pose problems for disposal based on current treatment plans. The analysis provides technical information for continued discussions between the DOE and affected States about disposal of MLLW and systematic input to waste treatment developers on disposal issues.
During the fiscal years 92-94 a joint group from Sandia/New Mexico and Sandia/California studied the development of new laser-plasma targets for projection x-ray or EUV (extreme ultraviolet) lithography. Our experimental and theoretical analyses incorporated target design as an integral part of the lithographic optical system. Targets studied included thick solid targets, thin-foil metal-coated targets, and cryogenic targets. Our complete measurement suite consisted of x-ray conversion efficiency measurements, source size imaging, source x-ray angular distribution measurements, debris collection, and source EUV spectrum. Target evaluation also included the variation of laser characteristics, such as, laser intensity, spot size, wavelength, pulselength, and pulseshape. Over the course of these experiments we examined targets using KrF (248nm), XeCl (308nm), and CO{sub 2} (10.6 {mu}m) lasers. While debris issues now dominate research in this area, final details were concluded on our understanding of material spectra and radiation transport of 13 run light in laser-plasmas. Additionally, conclusive results were obtained with 308 rim light, showing the pulselength threshold below which plumes no longer limited the transmission of (and thus the conversion efficiency to) 13 nm radiation.
