The Magma Energy Program is a speculative endeavor regarding practical utility of electrical power production from the thermal energy which reside in magma. The systematic investigation has identified an number of research areas which have application to the utilization of magma energy and to the field of geothermal energy. Eight topics were identified which involve thermal processes and which are areas for the application of the techniques of numerical simulation. These areas are: (1) two-phase flow of the working fluid in the wellbore, (2) thermodynamic cycles for the production of electrical power, (3) optimization of the entire system, (4) solidification and fracturing of the magma caused by the energy extraction process, (5) heat transfer and fluid flow within an open, direct-contact, heat-exchanger, (6) thermal convection in the overlying geothermal region, (7) thermal convection within the magma body, and (8) induced natural convection near the thermal energy extraction device. Modeling issues have been identified which will require systematic investigation in order to develop the most appropriate strategies for numerical simulation. It appears that numerical simulations will be of ever increasing importance to the study of geothermal processes as the size and complexity of the systems of interest increase. It is anticipated that, in the future, greater emphasis will be placed on the numerical simulation of large-scale, three-dimensional, transient, mixed convection in viscous flows and porous media. Increased computational capabilities, e.g.; massively parallel computers, will allow for the detailed study of specific processes in fractured media, non-Darcy effects in porous media, and non-Newtonian effects. 23 refs., 13 figs., 1 tab.
Sensitivity studies have been conducted for the gas release from the Waste Isolation Pilot Plant (WIPP) using the TOUGH2 computer code with performance measures of peak repository pressure and gas migration distance at 1000 years. The effect of formation permeabilities including impermeable halite, two-phase characteristic curves including different models and residual saturations, and other variations was studied to determine their impact on the performance of the WIPP repository. 15 refs., 7 figs., 2 tabs.
An important aspect of environmentally-conscious operations is adoption of an aggressive waste minimization program. This paper describes the waste minimization and pollution prevention program at Sandia National Laboratories. Although Sandia's approach is patterned after the generic waste minimization models proposed by the Environmental Protection Agency and the Department of Energy, the specifics of implementation, and the potential for payoff, are influenced by the R D nature of Sandia's work. Key aspects of the program are discussed, including why Sandia is developing and conducting the program; objectives; elements of the program; our approach to implementation; the magnitude of the undertaking; and the expected payoff. 3 refs., 2 figs.
The standard operating mode produces bremsstrahlung with an endpoint energy of about 18 MeV. This paper describes a new mode with a 8.5 MeV endpoint energy and the same standard mode pulse characteristics achieved by operating only half of the accelerator at full charge with the advantage of minimal setup time. An extension of the new half-voltage mode is to use the other half of the accelerator for delivering a second pulse at a later time with the same technique. The double pulse mode is ideal for beam generation which requires a long interpulse time in the millisecond regime. The beam characteristics of the two half-voltage pulses are nearly identical with the nominal radiation pulse full width at half maximum of 21 ns and 10--90 risetime of 11 ns recorded by the same Compton diode radiation monitors on instruments triggered 30 ms apart.
A series of shock-loading experiments on a nitrocellulose-based (NC-based) gun propellant was conducted using a light-gas gun. The intent of this work was to characterize the shock sensitivity of the gun propellant. The initial objectives were to obtained Hugoniot data and to investigate the pressure threshold at which a reaction initiates. For the Hugoniot/reaction threshold experiments, 1/4-length grains of propellant were mounted on the front of projectiles and were impacted onto either polymethylmethacrylate (PMMA), fused silica or sapphire targets at velocities as high as 1.4 mm/{mu}s, the upper limit of the gun. The particle velocity data obtained from the VISAR (Velocity Interferometer System for Any Reflector) records for the propellant fit a Hugoniot curve found in the Russian literature for a double-base, NC-nitroglycerine propellant. The density initial bulk sound velocity, and empirical parameter S values for the gun propellant were 1.63 g/cm{sup 3}, 1.70 mm/{mu}s and 1.85, respectively. VISAR data were also used to obtained the ignition threshold pressures of the gun propellant. Reactions were observed at impact pressures of 2.6 GPa and above. 5 refs., 6 figs., 1 tab.
We report on the use of a deposition/etch approach to the loss of selectivity problem, using high activity fluorine chemistries in the etch step. Proof-of-concept experiments were initially performed in a hot wall system, the excellent results obtained lead us to prove out the concept in a commercially available cold wall Genus reactor. We observed that WF{sub 6} is ineffective as an etchant of W. The technique has been able to produce perfectly selective depositions 1 micron thick in both hot wall, and cold wall, systems. Sheet resistivity values and film morphology are good. 9 refs., 4 figs., 1 tab.
This paper's main result is an O(({radical}{bar m}lgm)(n lg n) + mlg n)-time algorithm for computing the kth smallest entry in each row of an m {times} n totally monotone array. (A two-dimensional A = a(i,j) is totally monotone if for all i{sub 1} < i{sub 2} and j{sub 1} < j{sup 2}, < a(i{sub 1},j{sub 2}) implies a(i{sub 2},j{sub 1})). For large values of k (in particular, for k=(n/2)), this algorithm is significantly faster than the O(k(m+n))-time algorithm for the same problem due to Kravets and Park. An immediate consequence of this result is an O(n{sup 3/2} lg{sup 2}n)-time algorithm for computing the kth nearest neighbor of each vertex of a convex n-gon. In addition to the main result, we also give an O(n lg m)-time algorithm for computing an approximate median in each row of an m {times} n totally monotone array; this approximate median is an entry whose rank in its row lies between (n/4) and (3n/4) {minus} 1. 20 refs., 3 figs.
Presents a practical algorithm for partitioning a program into sequential threads. A thread is a sequence of instructions, possibly including branches, that can be scheduled as an indivisible unit on a von Neumann-like processor. The primary target of the proposed compilation strategy is large-scale parallel systems that rely on multithreading at the processor level to tolerate long communication latencies. As such, the algorithm incorporates a mechanism to balance the desire to maximize thread length with the desire to expose useful high-level parallelism. It can also exploit known dependency information (gathered through subscript analysis, for example). Although this paper focuses on non-strict (but not lazy) language semantics, the partitioning analysis is equally well suited to a non-strict language on a sequential machine or a strict language on a parallel multithreaded machine.
The Silver Bullet Skunk Works, and experimental product realization team at AT T Consumer Products, designed and shipped a new telephone answering system to market in eight months, approximately one year faster than previous AT T products of similar complexity. This paper outlines the Design for X'' (DFX) philosophies and the team structure that enabled the group to accelerate the Product Realization Process. The Answering System 1300, developed in record time, was a successful product that met its schedule and cost objectives, and sold out its entire high-volume manufacturing run. Lessons learned from the Skunk Works experience have since been applied to other development activities in AT T Consumer Products. 3 figs.
The refractory metals of Groups 5B and 6B and their alloys display a variety of unique physical and mechanical characteristics in addition to their high melting points. In turn, these characteristics make these materials strong candidates for severe service and specialized applications. However, these materials also present a variety of challenges with respect to both fabrication weldability and the in-service behavior of weldments, many of which are related to the dominant effects of interstitial impurities. This work reviews current understanding of the physical and joining metallurgy of these metals and their alloys with emphasis on fusion welding. Of specific interest are the role of impurities and alloy chemistry in fabrication and service weldability, the material processing route, eg. vacuum melting vs. powder metallurgy, the importance of welding process procedures and variables, weldment mechanical properties, and fracture behavior. Specific examples from the various alloy systems are used to illustrate general metallurgical and joining characteristics of this class of materials. 34 refs., 14 figs., 3 tabs.
Resistance Welding (RW) has been known for about a century and in common use for much of that time. Much knowledge has been accumulated concerning many aspects of the process. However, upon examining contemporary RW handbooks, a few subjects that have been overlooked'' were found. Usually, this oversight will not be important; however, when the RW process is being applied at its limits, these factors may become critical. In this paper we will discuss such overlooked'' factors as the Peltier and Thomson effects, and the dynamics of welding head motions and how they are affected by the current pulse. Examples taken from sheet metal and microwelding applications will be given as examples. 12 refs., 7 figs., 4 tabs.
Increasingly stringent air emission standards in various states has dictated the elimination of engineering finishes which are derived from high volatile organic compound (VOC) paint chemistries. In July 1989, Allied-Signal, Inc., Kansas City Division, Kansas City, Missouri, voluntarily closed its paint facility, due to non-compliance with local air emission standards. The following details the materials selection and evaluations which led to current processing using low VOC paints, which permitted the Allied Signal, Inc., paint facility to achieve compliance and resume operations. 1 tab.
We have developed a model which utilizes a probabilistic failure criterion to describe intergranular stress corrosion cracking (IGSCC). A two-dimensional array of elements representing a section of a pipe wall is analyzed, with each element in the array representing a segment of grain boundary. The failure criterion is applied repetitively to each element of the array that is exposed to the interior of the pipe (i.e. the corrosive fluid) until that element dissolves, thereby exposing the next element. A number of environmental, mechanical, and materials factors have been incorporated into the model, including: (1) the macroscopic applied stress profile, (2) the stress history, (3) the extent and grain-to- grain distribution of carbide sensitization levels, which can be applied to a subset of elements comprising a grain boundary, and (4) a data set containing IGSCC crack growth rates as function of applied stress intensity and sensitization level averaged over a large population of grains. The latter information was obtained from the literature for AISI 304 stainless steel under light water nuclear reactor primary coolant environmental conditions. The resulting crack growth simulations are presented and discussed. 14 refs., 10 figs.
Edge finishing and deburring of parts is a tedious operation that should be automated. This paper describes the use of direct-drive XY table in the automated edge finishing of machined parts. The table is faster and more accurate than an articulated robot, thus where planar motion in a small work area is sufficient it is preferable. Hybrid force/position control is used to guide the table (with mounted workpiece) past the tool and maintain the contact force at the desired level. A six-axis force sensor on the tool spindle is used to measure contact force. We identified a dynamic model for the table from experimental measurements and used this model to design a force/position controller for the table. An example application of the table in the deburring of an actual jet engine turbine hub is presented. 5 refs., 12 figs.
This paper justifies the need for and describes studies of brine chemistry under way for German and American high- and intermediate-level radioactive waste repositories in domal and bedded salt formation. In particular, it discusses the origin and composition of fluids that could enter these repositories and some sampling, modeling, and statistical techniques used to characterize them. 24 refs., 4 figs., 5 tabs.
Historically, characterization of fluid flow and transport of soluble elements in the unsaturated, or vadose, zone has been limited. Until recently, most of the interest in transport of water-soluble pollutants has been focused on aquifer contamination, i.e. saturated conditions. Vadose zone investigations are hampered by a lack of appropriate technology for the necessary measurements; little work has been done to relate laboratory measurements to field-scale effects; and development and validation of computational models has been limited, in part through lack of data. We describe here results of a small-scale field experiment in which existing technology is used to quantify fluid movement following controlled infiltration. 6 refs., 2 figs.
Sandia National Laboratories has considerable experience with video systems used for alarm assessment. Until recently the camera of choice for lighted security applications was the monochrome vacuum tube video camera. However, with recent advancements in the solid state imager technology, the integration of tube cameras in security systems may soon become obsolete. The sensitivity and resolution of solid state imagers is approaching that of vacuum tube imagers. In addition, solid state cameras have a relatively long lifetime and require little maintenance. Initial equipment costs are similar. Due to the increased performance of solid state imagers, Sandia has established an ongoing program to evaluate these cameras. The evaluations are performed mainly to verify manufacturers' specifications for resolution, sensitivity, and signal to noise ratio, which are the critical camera parameters that should be considered when designing video systems. This report defines these parameters, describes the test procedures, and provides test results. 1 figs., 2 tabs.
Analysis of an intermittent failure to write the 1'' state to a particular memory location at low temperature ({minus}55{degree}C) in a 16K {times} 1 CMOS SRAM is presented. The failure was found to be due to an open metallization at a metal-to-silicon contact. The root cause of the failure was poor step coverage of the metallization over an oxide step. A variety of failure analysis techniques including dynamic electron beam analysis at low temperature using a Peltier cold stage were employed to study the intermittently failing SRAM. The failure site was located by using capacitive coupling voltage contrast analysis. PSPICE simulation, light emission microscopy, scanning electron microscopy, and focused-ion beam techniques were used to confirm the failure mechanism and location. The write cycle time of the failed IC was abnormally long, but within the allowable tester limit. The vulnerability of other ICs to failure by open metallization in metal-to-silicon contacts is reviewed. 8 refs., 10 figs., 2 tabs.
Zeolite-based tritium lamps are a possible alternative to traditional tritium gas tube light sources. Rare earth luminescing centers may be ion-exchanged into zeolite matrices. Close proximity of tritium atoms to the rare earths can be provided by highly tritiated water sorbed within the pore structure of the zeolite aluminosilicate matrix. Zeolites are optically clear and radiation stable. Light outputs from tritium-loaded zeolites are shown here to exceed 2{mu}W/cm{sup 2}, with good stability. Procedures for obtaining light sources are presented and results are discussed. The possible use of these luminescent materials as process monitors for zeolite absorption columns in tritium service is also discussed. 13 refs., 3 figs.
For 15 years, the United States Department of Energy has worked with industry, both utilities and manufacturers, to develop the technology of solar central receiver power plants. In this type of plant, sunlight is concentrated by a field of sun-tracking mirrors, called heliostats, onto a centrally located receiver. The solar energy is collected in the form of a heated fluid, which is used to generate steam to power a conventional turbine generator. For a number of reasons, molten nitrate salt is now the preferred heat transfer fluid. Commercial plants will be sized between 100 and 200 MW. The impetus for developing central receivers comes from their unique advantages: (1) They produce clean, reliable, low-cost electricity; (2) they have practical energy storage that provides a high degree of dispatchability (annually up to 60%) -- without fossil fuels; and, (3) they are environmentally benign. Development efforts around the world have brought the technology to the brink of commercialization: The technical feasibility has been proven, and cost, performance, and reliability can be confidently predicted. Plans are currently being developed for the final steps toward commercial central receiver power plants. 24 refs., 7 figs.
To provide a method for addressing the uncertainty associated with conceptual models developed for performance assessment of waste management sites, probabilistic networks have been applied to the conceptual model development process. The application of probabilistic networks provides a graphical representation of the reasoning process that goes into developing conceptual models. Probability tables associated with decision points in the process provide a quantification of the uncertainty that is associated with the resulting conceptual models. To support the development of this probabilistic network, a formal process is being designed and implemented to elicit expert information about the conceptual model development process. This paper discusses the approach to designing this expert judgment elicitation process. 10 refs.
Conference Record - 7th Biennial IEEE-USA Careers Conference: Change and Competitiveness and Careers
Cannon, T.
Engineers invest several years becoming skilled in the many disciplines necessary to effectively carry out analysis, design and development. This typically includes math, physics, computer science, and special study in their core area of expertise. However, once promoted into management, engineers use less and less of these hard-earned technical skills and find themselves operating in nontechnical arenas in which they have little or no formal training. (The formal training that they do get is often through company-sponsored courses, lacking both the rigor and cohesiveness that they have grown accustomed to in their engineering curriculum.) Often, what they are exposed to are continually varying management doctrines that resemble the flavor of the month, each laying claim to the true secrets of motivation, productivity, and organizational competitiveness. Under such circumstances, it is difficult for the neophyte manager to sort out fact from fancy, and help from hype. It therefore would be helpful to put such theories in perspective and present them in a form most easily digested by technical managers, i.e., from an analytical point of view. This paper attempts to do just that. There are many factors that influence a manager's career progression. One of the most rational factors is how the manager's actions affect the productivity of his or her group. This paper focuses on principles and techniques that a manager can, and should, employ to improve group productivity and enhance his or her opportunities for further advancement. 9 refs.
The short-transverse (S-T) stress corrosion cracking (SCC) behavior of Al-Li-CU alloy 2090 was studied using a static load SCC test technique. Time to failure was measured as a function of applied potential in several different environments. Rapid SCC failures (< 10 hours) were observed only when the following criteria were satisfied: E{sub br, T1} < E{sub applied} < E{sub br, matrix} where potentials refer to the breakaway potentials of the subgrain boundary T{sub 1} (Al{sub 2}CuLi) phase and the {alpha}-Al matrix phase. E{sub br} values were measured using potentiodynamic polarization of bulk materials intended to simulate the individual phases found in the subgrain boundary region. Results strongly suggest an anodic dissolution based SCC mechanism for this alloy where selective dissolution of T{sub 1} on the subgrain boundary is a critical step. The unusual pre-exposure embrittlement phenomenon demonstrated by Al- Li alloys is also shown to be consistent with these simple SCC criteria. 21 refs., 9 figs., 6 tabs.
One of the possible consequences of disruptions is the generation of runaway electrons which can impact plasma facing components and cause damage due to high local energy deposition. This problem becomes more serious as the machine size and plasma current increases. Since large size and high currents are characteristics of proposed future machines, control of runaway generation is an important design consideration. A lumped circuit model for disruption runaway electron generation indicates that control circuitry on strongly influence runaway behavior. A comparison of disruption data from several shots on JET and D3-D with model results, demonstrate the effects of plasma motion on runaway number density and energy. 6 refs., 12 figs.
Benchmarking a network file server introduces some unique considerations over traditional benchmarking scenarios. Since the user is executing on a client system interconnected to the file server, the client and network must be provided for during benchmarking. During a recent procurement action, Sandia National Laboratories was challenged to develop a benchmark suite that would accurately test the network requirements. This paper describes the benchmark design and summarizes the experience gained from the benchmark executions. 8 refs., 2 figs.
The electromagnetic field in a mode-stirred chamber is a random process. Samples of this random process are random variables. Different realizations of this random variable can be obtained by changing the paddle-wheel angle, changing the frequency, or changing the location at which the sample is taken. Correlation widths can be defined for each of these three variables. For examples, the spatial correlation width is the distance a point sensor must be moved to realize an uncorrelated value of the field (paddle-wheel angle and frequency held constant). Likewise, the paddle-wheel correlation width is the angle through which the paddle wheel must turn to yield an uncorrelated value (location and frequency held constant). The frequency correlation width is the frequency change required to yield an uncorrelated value (location and paddle-wheel angle held constant). These values were determined experimentally for the sandia mode-stirred chamber by sampling the field at equal increments (for each variable) and calculating an autocorrelation function. The autocorrelation function is a random process (because it is calculated from a random process) and must be averaged to determine it width. The correlation widths were found to be less than 0.1{degree} for paddle-wheel angle, 50 kHz for frequency, and half a wavelength for spatial location. 4 refs., 3 figs., 2 tabs.
NMR and NQR reveal substantial structural changes in the metallic phase of LA{sub 2}CuO{sub 4+}{delta} which occur below 220 K. The oxygen octahedra in the metallic phase are not tilted at phase separation; upon cooling to 40 K considerable tilt has developed. The low temperature structure is highly disordered. 4 refs., 2 figs.
Although the feasibility of using PZT and PLZT films for optical data processing applications, such as optical storage disks, image comparators, and spatial light modulators, has clearly been established, most of the critical parameters related to the storage and readout processes still need to be evaluated. Optical readout techniques capable of nondestructively determining the value of polarization are based either on the quadratic electrooptic effect or on a photocurrent response. In reflection, large electrooptic retardations (>60{degrees}) have now been achieved with thin PZT films ({approx equal} 0.5 {mu}m) under conditions that optimize interference effects. These results are quite attractive for device applications. Model calculations, based on the equations of reflection ellipsometry, have been used to develop a framework for understanding those results. The magnitude of the photocurrent response has also been used to determine the polarization state. However, the photocurrent always has the same sign, regardless of the sign of the polarization, which suggests the presence of a strong bias field due to at least one of the interfaces. In addition, the accumulation of space charge after a succession of measurements suppresses the photocurrent transient, which severely limits the utility of a photocurrent based readout. 7 refs., 9 figs.
Basic to our knowledge of the science of welding is an understanding of the melting efficiency, which indicates how much of the heat deposited by the welding process is used to produce melting. Recent calorimetric studies of GTAW, PAW, and LBW processes have measured the net heat input to the part thereby quantifying the energy transfer efficiency and in turn permitting an accurate determination of the melting efficiency. It is indicated that the weld process variables can dramatically affect the melting efficiency. This limiting value is shown to depend on the weld heat flow geometry as predicted by analytical solutions to the heat flow equation and as demonstrated by the recent empirical data. A new dimensionless parameter is used to predict the melting efficiency and is shown to correlate extremely well with recent empirical data. This simple prediction methodology is notable because it requires only a knowledge of the weld schedule and the material properties in order to estimate melting efficiency. 22 refs., 16 figs.
The contact of aluminum-based melts with liquid water has been shown to be explosive in many experiments performed by the aluminum industry and in several nuclear reactor experiments and accidents. In order to obtain quantitative information relating to the fuel-coolant interactions that might occur with aluminum-based fuel, a laboratory-scale experimental study is being performed at Sandia National Laboratories. The overall objective of this research program is to provide an understanding of the mechanism of steam explosions with the melt compositions expected in several hypothetical core meltdown accident scenarios in production reactors. In this program it has been demonstrated that rapid exothermic metal-water reactions can accompany the steam explosions under certain conditions resulting in enhanced energy release and in the concomitant generation of hydrogen. 4 refs., 2 figs.
A hydraulic fracture stimulation conducted during 1983-1984 in non-marine, deltaic, Mesaverde strata at a depth of 7100 ft (2164 m) was cored in a deviated well in 1990. The observed fracture consists of two fracture intervals, both containing multiple fracture strands (30 and 8, respectively). While the core had separated across many of the fracture strands during coring, the rock remained intact across 20 of the strands, preserving materials within the fractures. Nine of the remaining intact strands were split open, revealing abundant gel residue on the surfaces of every fracture examined. Of 7 strands associated with major bedding planes, 4 displayed offsets of 1-3 mm at the planes and 3 strands had their growth terminated at the planes, showing the importance of bedding (petrophysical heterogeneities) on fracture propagation. Implications of all these findings for hydraulic fracture design and analysis are also addressed.
The INTEROP Achievement Award will be given to those customer organizations that make the most effective use of internetworking technology to further their own specific business aims. This paper is an application for this award by Sandia National Laboratories. Given are the network application, topology, and the types of systems to which it is applied.(JEF)
One problem with electromagnetic time domain finite-difference simulations in cylindrical coordinates is the rapidly decreasing characteristic dimension of the cells as r approaches zero. In order to satisfy the Courant stability condition a small time step is needed to insure stability, which is undesirable because it increases the cost of the simulation. In our presentation, we will describe a method which uses a rectangular grid and an annular cylindrical grid which overlap to perform electromagnetic simulations of cylindrical geometries. The two grids are connected by interpolating the field at the grid points of one grid using field values from the second grid. 2 refs.
Solder joints in electronic packages are electrical interconnections that also function as mechanical bonds. The solder often constrains materials of different coefficients of thermal expansion that, when thermal fluctuations are encountered, causes the solder joint to experience cyclical deformation. Due to the catastrophic consequences of electrical or mechanical failure of solder joints, a great deal of work has been performed to develop a better understanding of the metallurgical response of solder joints subjected to thermomechanical fatigue. This work reviews the microstructural and mechanical evolution that occurs in solder joints during thermomechanical fatigue. The eutectic Sn-Pb solder alloy is highlighted. Unlike most materials that experience thermomechanical fatigue, solder is commonly used at temperatures of up to nine-tenths of its melting point. Therefore extensive creep, solid state diffusion, recrystallization and grain growth occur in this alloy resulting in the evolution of a heterogeneous coarsened band through which failure eventually takes place. Two other solder alloys are compared with the Sn-Pb eutectic, a Pb-rich Sn-Pb alloy and a ternary near eutectic (40In-40Sn-20Pb, all alloys are given in wt. %). The Pb-rich alloy is a precipitated single phase matrix that does not evolve during thermomechanical fatigue and subsequently has a shorter lifetime. Conversely, the 40In-40Sn-20Pb solder is a two phase eutectic in which the microstructures refines during thermomechanical fatigue giving it a longer lifetime than the eutectic Sn-Pb solder. The microstructural processes that occur during thermomechanical fatigue and final fracture behavior are discussed for the three solder alloys. 47 refs., 14 figs.
The use of ground-based lasers to launch small payloads but large total masses into low-Earth orbit may prove to be the most innovative and potentially economical approach for accomplishing this important mission. Of the several possible schemes for laser propulsion, two are examined: (1) ablative momentum transfer using pulsed lasers; and (2) heat exchanger thrusters in conjunction with CW lasers. For an entry-level payload of {approximately}50 kg it is found that the former yields payload-to-power ratios < 0.5 kg/MW with a requirement for an average laser power of at least 100 MW, whereas the latter might yield 1 to 3 kg/MW with a laser power of several 10s of MW. One of the promising approaches that could yield a driver for such a system is the reactor-pumped laser FALCON, which scales to these power levels with the potential for long run times.
The Space Exploration Initiative (SEI) seeks to reestablish a U. S. program of manned and unmanned space exploration. The President has called for a program which includes a space station element, a manned habitation of the moon, and a human exploration of Mars. The NASA Synthesis Group has developed four significantly different architectures for the SEI program. One key element of a space exploration effort is the power required to support the missions. The Power Specialty Team of the Synthesis Group was tasked with assessing and evaluating the power requirements and candidate power technologies for such missions. Inputs to the effort came from existing NASA studies as well as other government agency inputs such as those from DOD and DOE. In addition, there were industry and university briefings and results of solicitations from the AIAA and the general public as a part of the NASA outreach effort. Because of the variety of power needs in the SEI program, there will be a need for multiple power system technologies including solar, nuclear and electrochemical. Due to the high rocket masses required to propel payloads to the moon and beyond to Mars, there is great emphasis placed on the need for high power density and high energy density systems. Power system technology development work is needed and results will determine the ultimate technology selections.
Shockwave techniques have been used for decades to study the dynamic states of matter in temperature and pressure regimes inaccessible by other methods. These techniques have been employed in a wide variety of scientific, military, and commercial applications. A principal scientific objective has been to determine high-pressure equations of state (EOS) to ultra-high pressures; pressures of tens of Mbar have been reported for several materials. Most recently, these methods have been used for studies of thermophysical properties under shock compression, including phase transition kinetics, and mechanical properties, such as the high-pressure yield strength. In this paper, a brief discussion of recent developments in high velocity launchers is given. Advances in techniques for subjecting materials to a wide range of loading conditions is presented, including selected illustrations of shockwave measurements to Mbar pressures. 54 refs.
The modern investigation of the thermochemical behavior of salt started in the mid-1930's and, for what appears to be a very narrow discipline, salt mechanics'' has acquired considerable technical depth and sophistication. The last three decades have been especially productive in constitutive model development and laboratory investigations of time-dependent creep behavior. This has been largely due to anticipated use of domal or bedded salt deposits as sites for radioactive waste repositories and to expanded need for hydrocarbon and feedstock storage caverns. Salt is an interesting material, in that it is metal like''; and, therefore, constitutive modeling can draw upon a large body of metal deformation information to arrive at appropriate models of behavior. Testing apparatus and methods have centered on either uniaxial or triaxial compression to obtain steady state and transient creep responses. Flow and fracture potentials have been defined. Validation attempts of the models against field data, although limited, have proved promising. 27 refs.
Conference Record - 7th Biennial IEEE-USA Careers Conference: Change and Competitiveness and Careers
James, M.R.
Upward Feedback is a program that gives employees and opportunity to anonymoulsy provide their manager with feedback concerning the manager's job performance. It is an opportunity for managers to receive confidential feedback evaluating their implementation of corporate values and management behaviors as perceived by those who work for them. This feedback can come from employees who report directly to the manager, that is, one level below them (referred to as direct reports), or from those two reporting levels below them (referred to as skip-level reports). Managers then share information with their employees in feedback meetings and develop action plans to address areas of concern. Sandia National Laboratories has developed and implemented an Upward Feedback Pilot Program and follow up survey. This paper discussed the program and the lessons learned.
Typical aerospace joints lead to apertures which are very narrow and thick. We develop a systematic analytical treatment of this type of aperture (precise conditions of validity given in the text), although the results are also applicable to apertures on a thin conducting body. An antenna integral equation with an equivalent antenna radius is used to describe the voltage across a narrow and thick aperture in a perfectly conducting plane. The result shows the voltage across the aperture has very high Q (quality-factor) resonances, because the equivalent radius is exponentially small. Transmitted power also exhibits similar behavior. When metallic and gasket losses are included, a nonlocal antenna model together with a local transmission line model is used to describe the voltage across the aperture. Good metallic walls, such as aluminum, are found to significantly reduce the penetration of an aperture of typical dimensions. Gaskets with relatively small loss tangents also result in significant penetration reductions. A simple transmission line with uniform loading is used to approximate the governing equation described in. In the lossless limit and for moderate fatness parameter this simple transmission line model is comparable in accuracy to King's three-term theory. The loading of the bolts or hinges is demonstrated to act in many cases as a short. Finally, the low frequency penetration for a narrow slot aperture of arbitrary depth is characterized by the equivalent polarizabilities (dominating longitudinal component) as a function of the ratio of the depth to the width and ratio of the length to the width. A general relationship is shown to exist between the equivalent radius and the transverse line dipole moments of a slot aperture with depth. The longitudinal equivalent polarizabilities of antennas and slot apertures are used to derive a coupling energy bound for a step function EMP. 9 refs., 8 figs.
The strength of deuterium bonding to the walls of closed cavities within Si was determined in ion-beam experiments. These studies circumvented an inherent indeterminacy in the analysis of external-surface desorption and thereby allowed the Si-H surface bond energy to be quantified for the first time. The bond energy is 2.5 {plus minus} 0.2 eV for submonolayer coverages. 14 refs., 3 figs.
Scan path testing and debugging offers a structured, proven way to debug and test arbitrarily complex electronic systems. The interface and equipment requirements are far lower than traditional debug and test techniques. The system is also completely testable even when physically remote from the lab where it was originally developed. This report describes our experience using scan techniques to debug the EPSILON-2 processor board, a system with over 300 ICs and over 2500 independently controllable and observable test points. The debug time of the circuit was greatly reduced by the adoption of scan path methodology. The use of expensive test equipment was drastically reduced, and the level of control of the circuitry increased. We have run tests on the processor from physically remote sites. Our experiences are described, and the adoption of scan path techniques is shown to be simple enough that it should be useful in all electronic projects. 8 refs., 12 figs.
Sandia National Laboratories is a large multi-program DOE laboratory. The Recorded Information Management Division (RIM) has an expanding mission to meet Sandia's needs for cost-effective management in information from creation to final disposition in accordance with applicable regulations and requirements. An analysis based on the need to meet requirements and to improve business practice was successful in convincing management to allocate increased resources to the RIM Compliance Project.
Historically, the electronics industry has always attempted to increase the speed of electronic components and decrease the size of electronic assemblies by developing and manufacturing smaller and faster basic level components (e.g., integrated circuits). However, it is now becoming apparent that the next significant advancement in electronic assembly size and speed may come not as a result of smaller and faster devices, but rather as a consequence of smaller and more closely spaced packages. This increased packaging density will occur at early levels of assembly as industry moves towards multichip modules. It will also occur at later packaging steps as industry continues to expand the use of surface mount technology (SMT) and mixed mounting technology (through hole attachment as well as SMT on one circuit board). Furthermore, there will be an increased propensity to use higher packaging density on printed wiring boards (PWB) and to place more PWB's in a given volume at yet the next level of packaging. One class of materials on which this advanced packaging technology will place severe new demands will be the alloys used to join assemblies and subassemblies (e.g. solders and brazes). These materials will be taxed both from the perspective of enhanced manufacturability as well as greater in-service robustness. It is the objective of this paper, through the use of selected case studies, to illustrate how advanced microstructural characterization techniques can be used to improve packaging technology. The specific case studies discussed are: (1) Microstructural Characterization of Solders, (2) Microstructural Characterization of Solder Joint Embrittlement of Leaded, Surface Mount Transistors (3) Microstructural Characterization of Metal/Ceramic Brazes in Electronic Applications, and (4) Microstructural Characterization of Direct Brazing of Graphite to Copper. 25 refs., 16 figs.
A number of models that predict the impulse generated in solid targets by short high-intensity radiation loads are described. It is shown that the impulse is insensitive to the details of the energy deposition and interaction processes. Thus with the proper nondimensionalization and normalization, all the models are known to be very nearly equivalent. 5 refs., 5 figs., 1 tab.
Acoustic emissions and conventional strain measurements were used to follow the evolution of the damage surface and the plastic potential in a limestone under conditions of triaxial compressions. Confining pressures were chosen such that macroscopically, the limestone exhibited both brittle and ductile behavior. The parameters thus derived are useful for modeling the deformation of a pressure-dependent material and for computing when localization would occur. 10 refs., 8 figs.
The Gaseous Electronics Conference (GEC) RF Reference Cell was developed to enhance studies of radiofrequency (rf) discharge systems analogous to those used to fabricate microelectronic devices. The Reference Cell concept includes both a standard discharge-chamber design and a set of diagnostic tools that can be used to verify that different Cells behave similarly. Voltage and current measurements in Reference Cells in the United States show that, with proper care, plasmas that behave in a similar manner can be generated in different Cells. The versatility of the Reference Cell is illustrated by results on the use of planar laser-induced fluorescence imaging to obtain two-dimensional spatial profiles of SO{sub 2} in an SF{sub 6}/O{sub 2} rf discharge. 4 refs., 5 figs.
We have used the highly sensitive technique of Photothermal Deflection Spectroscopy (PDS) to measure changes in the infrared absorption spectra of MEHPPV, P3HT and Polydiacetylene-4BCMU induced by pumping these polymers with light above the {pi}--{pi}* transition energy. In contrast to previous chopped light transmission measurements of these effects, the PDS technique can directly measure the buildup or decay of the absorption coefficient, {alpha}, on the time scale of second to days. In the case of MEHPPV we observe that the time scale of seconds to days. In the case of MEHPPV we observe that above-gap light causes the appearance of a broad infrared peak in {alpha}, which continues to grow-in hours after the pump light is first applied. For this polymer the general shape of the absorption spectra in the unpumped state mimics the photo-induced changes, suggesting that remnant photo-induced states determine the maximum transparency observed under normal experimental conditions. For P3HT and to a lesser extent, MEHPPV, we also observe irreversible photo-induced absorption components which we tentatively identify with photo-induced oxidation of the polymer matrix. 10 refs., 8 figs.
Present practice in most computer codes intended for the solution of dynamic mechanics problems is to use the classical infinitesimal plasticity relations together with the Jaumann stress rate to account for finite rotations. Use of the Jaumann stress rate is known to lead to oscillating stress-strain response in simple shear at large deformations for elastic and some plastic relations, and is limited to isotropic material descriptions. Formulations of finite deformation plasticity based on the Lagrangian reference configuration and an unrotated configuration have been proposed which, in principle, should overcome these limitations. The latter has been implemented in a finite element computer code. In this paper, it is shown how a Lagrangian description based on the reference configuration may be implemented in computer codes, and how it may be translated into a corresponding Eulerian description based on the current configuration and a description based on the unrotated configuration for comparison with currently used descriptions. 11 refs.
This paper presents information on measures taken by Sandia National Laboratories to prepare for environmental, safety, and health compliance assessments conducted by Tiger Teams'' at Department of Energy facilities.
Woven Kevlar fabrics exhibit a number of beneficial mechanical properties which include strength, flexibility, and relatively low density. The desire to engineer or design Kevlar fabrics for specific applications has stimulated interest in the development of theoretical models which relate their effective mechanical properties to specific aspects of the fabric morphology and microstructure. In this work the author provides a theoretical investigation of the large deformation elastic response of a plane woven Kevlar fabric and compares these theoretical results with experimental data obtained from uniaxially loaded Kevlar fabrics. The theoretical analysis assumes the woven fabric to be a regular network of orthogonal interlaced yarns and the individual yarns are modeled as extensible elastica, thus coupling stretching and bending effects at the outset. This comparison of experiment with theory indicates that the deformation of woven fabric can be quite accurately predicted by modeling the individual yarns as extensible elastica. 2 refs., 1 fig.
The Modular Integrated Video System (MIVS) Image Processing System (MIPS) was developed to assist the International Atomic Energy Agency (IAEA) Inspectorate in the safeguards review of MIVS surveillance data. MIPS is designed to review MIVS surveillance data automatically; firstly detecting significantly changed images and secondly identifying if the changed images show IAEA defined objects of safeguards interest. To achieve this, MIPS uses both digital image processing and neural network techniques. A change detector uses image processing techniques to identify significantly changed images. The MIPS neural network classifier detects images which may show an important object(s). The neural network is trained , i.e., given example images showing the objects that it must recognize, for each different facility. The MIPS change detection algorithms reduce the original MIVS data by eliminating images without significant activity. The MIPS neural network algorithms further reduce this data by eliminating images which may not show a safeguards significant object. The images analyzed by both the change detector and the neural network are available for inspector review. The MIPS algorithms are implemented in commercially available hardware. A high-level menu-driven system interface allows inspectors to train the neural network and to operate both the change detection and neural network classification. An evaluation program was conducted jointly by Sandia National Laboratories (SNL) and the IAEA to determine the systems capabilities on a variety of MIVS data. The MIPS processing techniques and the user interface were evaluated by IAEA inspectors. Performance tests were also completed on a variety of MIVS data. This paper provides a description of the Class II MIPS and the evaluation program and reports on the results of this joint evaluation. 7 refs., 4 figs., 3 tabs.
Gas conductivities of narrow natural fractures in sandstone and chalk were measured under varying stress and pore pressure conditions and showed a decrease in conductivity with increasing net stress. Natural fractures in mudstones exhibited continuously decreasing conductivity upon application of stress, so that correlatable conductivity data could not be obtained. Effective-stress-law behavior for the sandstone and chalk fractures were examined, giving α values in the range of 0.8-1.06, where α is the parameter in the effective-stress law, σ - αP. The value of α for the fracture in chalk was nearly constant, but the values for the fracture in sandstone tended to decrease with increasing stress. Transition Reynold's numbers and turbulence factors for flow through the chalk and sandstone fractures were determined, yielding turbulence factors ranging from 6.0-20×106 ft-1 (2.0-6.6×10-5 cm-1) for differently stressed fractures. The entire flow behavior of these natural fractures, including conductivity, effective-stress law, and turbulence, is controlled by stress and pore pressure. As a result, pressure depletion during production will significantly change the productivity of a reservoir with similar natural fractures.
Betavoltaic power sources operate by converting the nuclear decay energy of beta-emitting radioisotopes into electricity. Since they are not chemically driven, they could operate at temperatures which would either be to hot or too cold for typical chemical batteries. Further, for long lived isotopes, they offer the possibility of multi-decade active lifetimes. Two approaches are being investigated: direct and indirect conversion. Direct conversion cells consist of semiconductor diodes similar to photovoltaic cells. Beta particle directly bombard these cells, generating electron-hole pairs in the semiconductor which are converted to useful power. Many using low power flux beta emitters, wide bandgap semiconductors are required to achieve useful conversion efficiencies. The combination of tritium, as the beta emitter, and gallium phosphide (GaP), as the semiconductor converter, was evaluated. Indirect conversion betacells first convert the beta energy to light with a phosphor, and then to electricity with photovoltaic cells. An indirect conversion power source using a tritium radioluminescent (RL) light is being investigated. Our analysis indicates that this approach has the potential for significant volume and cost savings over the direct conversion method. 7 refs., 11 figs.
Over the past three years, several experiments have been conducted at the Brookhaven National Laboratory Radiation Effects Facility. These experiments have been investigations of proton induced radiation effects in individual electronic components, circuits, operational subsystems and full systems. Our investigations using 170--200 MeV protons have included total dose effects up to 12 Mrad, dose rate effects of the ionizing radiation in the 10{sup 5} to 10{sup 8} rad/s range, the displacement damage effects of the protons up to 10{sup 15} p/cm{sup 2}, and the proton induced thermal shift and thermal-rate effects. The target thickness of many test devices was an appreciable fraction of the range of 200 MeV protons. In our proton beam testing experiments at BNL, dosimetry placed downstream of the target consistently yielded higher dose in rad and in particle fluence than in dosimetry placed upstream of the target. We designed and performed an experiment to study this dose enhancement. The objective of the experiment was to determine the effect of sample thickness on our three methods of dosimetry. The data from the PIN diodes and tantalum calorimeters were consistent and followed the expected DE/DX curve. They show a dose enhancement effect. The proton beam interacts and loses energy as it travels through thick targets. The exiting lower energy beam deposits more energy into the dosimetry because the stopping power increases with decreasing proton energy.
In this paper we review three proposed mechanisms for GaAs ALE and review or present data support or contradiction of these mechanisms. Surface chemistry results clearly demonstrated that TMGa irreversibly chemisorbs on the Ga-rich GaAs(100) surface. The reactive sticking coefficient (RSC) of TMGa on the adsorbate-free Ga-rich GaAs(100) surface was measured to be {approximately}0.5, conclusively demonstrating that the selective adsorption'' mechanism of ALE is not valid. We describe kinetic evidence for methyl radical desorption in support of the adsorbate inhibition'' mechanism. The methyl radical desorption rates determined by temperature programmed desorption (TPD) demonstrate that desorption is at least a factor of {approximately}10 faster from the As-rich c(2 {times} 8)/(2 {times} 4) surface than from the Ga-rich surface. It is disparity in CH{sub 3} desorption rates between the As-rich and Ga-rich surfaces that is largely responsible for GaAs ALE behavior. A gallium alkyl radical (e.g. MMGa) is also observed during TPD and molecular beam experiments, in partial support of the flux balance'' mechanism. Stoichiometry issues of ALE are also discussed. We have discovered that arsine exposures typical of atmospheric pressure and reduced pressure ALE lead to As coverages {ge} 1 ML, which provides the likely solution to the stoichiometry question regarding the arsine cycle. 32 refs., 6 figs.
A procedure was developed to use solder technology in the assembly of a single-crystal quartz accelerometer. 87.5Au-12.5Ge (wt.%) solder films 0.5 {times} 10{sup {minus}6}, 1.0 {times} 10{sup {minus}6}, and 2.0 {times} 10{sup {minus}}6 m thick were formed by the electron beam deposition of individual layers of Au and Ge with thicknesses so that the bulk film composition equals the eutectic composition. Interdiffusion of the Au and Ge formed the solder; thermal-physical measurements showed the multilayer films to behave similarly to bulk 87.5Au-12.5Be solder in process thermal cycles. The 2.0 {times} 10{sup {minus}6}m thick quartz/Au-Ge/quartz bonds had an adhesive tensile strength of 17 {plus minus} 2 MPa. The strength increased to 29 {plus minus} 3 MPa and 27 {plus minus} 12 MPa after thermal shock and thermal cycle exposures respectively. The 1.0 {times} 10{sup {minus}6} m thick bonds exhibited strengths of 16 {plus minus} 3 MPa, 16 MPa and 15 {plus minus} 8 MPa in the as-fabricated, post-thermal shock, and post-thermal cycled samples, respectively. The 0.5 {times} 10{sup {minus}6} m joints produced a large degree of scatter in the strength values. Accelerometers assembled with the 2.0 {times} 10{sup {minus}6} m thick joints demonstrated a significant improvement in temperature performance as opposed to units fabricated with a polyimide adhesive. 8 refs., 12 figs., 8 tabs.
This paper is about the spatial resolution of x-ray microanalysis in thin foils. The theory of the scattering of an electron beam with a thin foil is discussed.
Upon becoming Secretary of the Department of Energy (DOE), Admiral Watkins first pledged to Congress that he would clean-up'' the nuclear weapons production complexes and then initiated many changes in the way DOE facilities are operated. He generated new orders regarding environments, safety, and health and created investigation units called Tiger Teams'' to check on how well his orders were being followed. During the spin-up of this massive undertaking, DOE decided to include all its facilities and not just the ones involved in nuclear production. This resulted in research and development labs, such as Lawrence Livermore, Los Alamos, and Sandia National Laboratories being subjected to more stringent regulations. This paper addresses the action Sandia National Laboratories has taken during the past year, particularly in regard to its pulsed-power accelerators, to come into compliance with the new DOE orders. 2 tabs.
The measurement and understanding of the fracture toughness of ductile cast irons, DCI, are critical to the analysis of nuclear transportation casks made from these alloys. Cask containment must be assured for all loading events from normal handling to accidents during which high loads can be delivered at elevated rates. Cask walls are commonly in the range of 20 to 50 cm thick (or greater) in order to provide requisite nuclear shielding, and this requires that associated mechanical constraint effects must be considered. At elevated temperatures (i.e., in the vicinity of ambient) DCI behaves in an elastic-plastic manner, even for large section sizes (B>20 cm) and moderately high loading rates. However, as the temperature is lowered or the loading rate is increased, ferritic DCI alloys exhibit a relatively sharp transition to linear elastic behavior, with a significant decrease in the fracture toughness. The fracture toughness of a DCI alloy has been measured using linear elastic and elastic-plastic experimental techniques. Measurements have been made as a function of temperature, loading rate and section size. The loading rates span the range which a cask could experience during normal transport and handling, as well as accident events. 15 refs., 7 figs., 4 tabs.
Sandia National Laboratories and the University of New Mexico's Anderson School of Management are developing a program which enables M.B.A. students to assist in commercializing Sandia developed technologies. Thus far, students have prepared detailed business plans (which include market analyses, design and development sections, and pro forma financials) for a wide range of technologies. Potential applications include waste management, cancer treatment, oil and gas transportation, coating of plastics, manufacturing and assembly, and parts inspections. By having graduate students conduct the research necessary to identify positive net-present-value projects, Sandia is able to interest private sector firms in its technologies.
Several countries propose to permanently dispose of spent reactor fuel as waste in geologic repositories. There is no basis for terminating safeguards on spent fuel, since it does not meet the criteria specified for termination, and conceivably it might be subsequently recovered and used for prohibited purposes. The paper proposed safeguards measures for spent fuel undergoing preparation, emplacement, recoverable storage, and after site closure which are consistent with other IAEA safeguards but which differ in detail, commensurate with the lesser risk of diversion relative to materials in other parts of the fuel cycle. The proposed measures rely on item accountability of discrete units, by means of containment and surveillance. The concept is consistent with the guidelines contained in Part I of the Safeguards Document, INFCIRC/153, but not entirely with Part II, which is based on verified material balances. After final site closure safeguards are limited to infrequent site observations, which would be sufficient to detect any attempts to recover the material. The paper points out the magnitude of effort required for recovery and the difficulty of concealing if from casual observation. 4 refs.
This report is an overview of advanced nonvolatile memory technologies. The memory technologies discussed are: floating gate nonvolatile memory technologies; SNOS nonvolatile technology; ferroelectric technology; and thin film magnetic memories.
This paper addresses the issue of collision avoidance in unknown or partially modeled environments using a capacitive sensor. An eight channel capacitance-based sensor system which can detect obstacles up to 400 mm (16 inches) away has been developed. This sensor can detect both conductive and non-conductive obstacles of arbitrary color and shape. The sensor hardware is reliable and inexpensive, and it may be fabricated using flexible printed circuit boards to provide whole-arm and joint protection for any robot or manipulator. Simple collision avoidance control algorithms have been implemented on a two-link robot arm. The sensor and control system enable the robot arm to avoid a conductive post and a concrete block. 13 refs., 9 figs.
This paper presents two algorithms that construct a set of initial (x, y, {theta}) configurations from which a given action will reliably accomplish a planar manipulation task. The first algorithm applies energy arguments to construct a conservative set of successful initial configurations, while the second algorithm performs numerical integration to construct a set that is much less conservative. The algorithms may be applied to a variety of tasks, including pushing, placing-by-dropping, and force-controlled assembly tasks. Both algorithms consider the task geometry and mechanics, and allow uncertainty in every task parameter except for the object shapes. Experimental results are presented which demonstrate the validity of the algorithms' output for two example manipulation tasks. 16 refs., 8 figs.
Sandia National Laboratories developed an Authenticated Secure Container System (ASCS) for the International Atomic Energy Agency (IAEA). Agency standard weights and safeguards samples can be stored in the ASCS to provide continuity of knowledge. The ASCS consists of an optically clear cover, a base containing the Authenticated Item Monitoring System (AIMS) transmitter, and the AIMS receiver unit for data collection. The ASCS will provide the Inspector with information concerning the status of the system, during a surveillance period, such as state of health, tampering attempts, and movement of the container system. The secure container is located inside a Glove Box with the receiver located remotely from the Glove Box. AIMS technology uses rf transmission from the secure container to the receiver to provide a record of state of health and tampering. The data is stored in the receiver for analysis by the Inspector during a future inspection visit. 2 refs.
The advent of optical storage has made the digital storage of documents a viable option from both a practical and legal perspective. However, the availability of Optical Disk Storage raises questions regarding the destruction of the stored records and standards of longevity, and the admissibility in court of records produced from optical storage has not been tested. This paper will attempt to address these issues. 6 refs.
The use of carbon materials in catalytic system has been traditionally associated with their properties as supports. There are, however, some literature data describing their use as catalysts. Our results show that no simple relationship exists between the catalytic activity of some carbon materials for selective cleavage of carbon-carbon bonds adjacent to condensed polyaromatic rings an the elemental composition or surface area of these materials. The activity is dependent, however, upon the precursor used to generate the carbon material. Moreover, for a given precursor the activity is determined by the method of conversion to the carbon material. It remains to be established what elements of structure are responsible for the observed activity in carbon materials that are catalytically active. 12 refs., 7 tabs., 1 fig.
The strain rate in steady shock waves is proportional to the fourth power of shock amplitude for a wide variety of materials over a broad range of strain rates. A model based on this observation gives good agreement not only with steady-wave profiles but also with data on non-steady waves in aluminum. In apparent contrast, data on vanadium and uranium at low strain rates indicates a departure from the fourth power law if the wave profiles are assumed to be steady. However, when predicted profiles are produced by allowing the waves to propagate and evolve over the actual experimental sample thickness, the fourth power model gives excellent agreement with the wave profile data even though the wave profiles in the calculations have not yet reached steady state. The implication is that the experimental data do not represent steady waves, and the model is predicting the correct evolution of non-steady waves in vanadium and uranium. 7 refs., 2 figs.
The National Competitiveness Technology Transfer Act of 1989 has opened up the vast resources of our nation's national laboratories to the electronics industry. The electronics industry stands to gain advanced technology development, increased competitiveness, resource-sharing, and technology protection from this act. Sandia National Laboratories can help our nation's companies and universities in developing and applying advanced, commercially valuable technologies and in solving technological problems. These technological areas are discussed. A clear, non-bureaucratic process of tapping the microelectronics expertise and resources of Sandia National Laboratories is presented.
Highly reactive coal pyrites and unstable museum specimens are easily distinguished from the stable pyrites by the growth of white crystals that cover samples exposed to room atmosphere for short periods of time. Continued exposure to the atmosphere will eventually cause the specimens to fall apart. The term rotten pyrite has been applied to museum specimens that fall apart in this way. SEM studies show that reactive (rotten) pyrites contain between 100 and 10,000 times more dislocations than stable pyrites. Shock-loading of a stable pyrite to 7.5 GPa and 17 GPa increased its reactivity by a factor of two, probably caused by an increase in the number of imperfections. However, shock-loading at 22 GPa decreased the reactivity of pyrite because the imperfections produced at the higher pressure were removed during annealing the sample received at the higher temperature. Although there was a factor of six difference between the most and least reactive shocked MCB (commercial pyrite) samples, shock-loading did not increase the reactivity of the MCB pyrite to that of the Queensland coal pyrite. The results in hand show that while shock-loading produces sufficient imperfections to increase the reactivity of pyrites, there is insufficient data to show that imperfections are the main reason why some coal pyrites are highly reactive. 9 refs., 1 fig., 1 tab.
Transmitting digital voice via packetized mobile communications systems that employ relatively short packet lengths and narrow bandwidths often necessitates very low bit rate coding of the voice data. Sandia National Laboratories is currently developing an efficient voice coding system operating at 800 bits per second (bps). The coding scheme is a modified version of the 2400 bps NSA LPC-10e standard. The most significant modification to the LPC-10e scheme is the vector quantization of the line spectrum frequencies associated with the synthesis filters. An outline of a hardware implementation for the 800 bps coder is presented. The speech quality of the coder is generally good, although speaker recognition is not possible. Further research is being conducted to reduce the memory requirements and complexity of the vector quantizer, and to increase the quality of the reconstructed speech. 4 refs., 2 figs., 3 tabs.
BA85 is a routine for the quantitative reduction of x-ray data collected from oxide samples in an electron microprobe. BA85 is based on the correction procedures developed by Bence and Albee and is coded in Flextran for use with the TASK8 microprobe operating system. Features include stoichiometry and statistical calculations, the use of a 90 - oxide A-factor matrix which contains all of the common valence states for such elements as Fe and Cr, the ability to analyze up to 45 oxides, and the ability to create and use mineral codes which permit associating up to 15 oxides with three letter mnemonic codes. Entering a mineral code results in the analysis of the oxides associated with it and the performance of one of 21 endmember calculations. 13 refs., 2 figs., 3 tabs.
This paper seeks to improve the synergism between computational aerodynamics and wind tunnel experimentation. In this paper, experimental and computational results are presented for a hypersonic vehicle configuration at Mach 8. Comparisons are made between experimental and computational results in order to improve the accuracy of both approaches. The basic vehicle configuration is a spherically blunted cone with a slice parallel with the axis of the vehicle. The half-angle of the cone is 10 deg. and the ratio of spherical nose radius to base radius in 10%. Onto the slice portion of the vehicle can be attached flaps with three different deflection angles; 10, 20, and 30 deg. All of the experimental results were obtained in the Sandia Mach 8 long duration, blow-down, hypersonic wind tunnel. Flow visualization results include surface oil flow, spark schlieren, and liquid crystal photographs and video. The liquid crystals were used as an aid in verifying that a laminar boundary layer existed over the entire body. An extensive uncertainty analysis was conducted to estimate quantitatively the accuracy of the measurement. Computational aerodynamic force and moment predictions are compared with the wind tunnel data. The Sandia Parabolized Navier-Stokes code is used to generate solutions for the sliced vehicle (no flap) and partial solutions for the flapped vehicle. For the geometry with the flap, an axially separated flow occurs and a time iterative Navier-Stokes code is used to provide comparisons with the data. This paper presents a portion of the results given in earlier works and also discusses new experimental results with this configuration.
Plotting and summary routines available for the TASK8 microprobe operating system are able to accept both spectral and quantitative data. All of the routines are able to be run as subroutines from within the TASK8 program or as stand alone programs. Additionally, the spectral plotting routine can be run from within a modified version of SQ. The quantitative routines currently in use with TASK8. Quantitative output can be sent by the summary program to a serial port that is connected to a VAX or PC in addition to printing it. The plotting codes have been written so that either a Tracor Northern TN2000 or a TN5xxx analyzer may be used with either a Hewlett Packard HP7221 series or a HP7470/HP7550 series plotter. The plotting routine for spectra incorporates a user definable usual was'' option to simplify most input procedures. The quantitative plotting routine offers numerous options including scale expansion, smoothing, auto-labeling, special symbols, and multiple pens. 5 refs., 5 figs.
A computational scheme is presented to solve the unsteady Navier-Stokes equations over a blunt body at high altitude, high Mach number atmospheric reentry flow conditions. This continuum approach is directed to low Reynolds/low density hypersonic flows by accounting for non-zero bulk viscosity effects in near frozen flow conditions. A significant difference from previous studies is the inclusion of the capability to model non-zero bulk viscosity effects. The grid definition for these low Reynolds number, viscous dominated flow fields is especially important in terms of numerical stability and accurate heat transfer solutions. 11 refs., 15 figs.
Difficulties in the accurate heat transfer computation of high speed, blunt body flows have been encountered by numerous researchers. The primary reason for these difficulties has been shown to be the grid dependency of the wall flux quantities. Obviously, the accuracy of the computed heat fluxes will, to a certain extent, depend on the particular numerical scheme employed. This article will be limited to the investigation of the flux vector splitting technique. An attempt has been made to develop procedures which will provide guidelines for selecting appropriate grid systems and, in particular, the grid line distribution near the surface for accurate heat transfer computations. The results have clearly shown the dependency of the heat flux quantities on the grid system. In addition, it is shown that changes in flow Mach number and/or Reynolds number may require further refinement of the grid system. 11 refs., 8 figs.
This paper describes a new technique for the detection of x-rays in electron column instruments used in microanalysis. In electron column instruments, the point source of x-rays is produced by the interaction of a focused electron beam with the sample. Neither of the conventional methods, wavelength dispersive (WDS) nor energy dispersive (EDS) based spectrometry, is optimized for low Z element quantitative analysis. In WDS applications, where the analyte elements are Be through P, chemical effects complicate the x-ray measurement process. Peak positions and shapes are altered, sometimes very strongly, by the electron configurations of the analyte atoms and neighboring atoms. In these cases, the ideal spectrometer would profile the peak and some small amount of continuum on either side of the peak such that an accurate peak area could be calculated. Present WDS spectrometers are serial in nature and cannot directly measure peak areas, often causing errors in the determination of light element concentrations. Bastin and co-workers have developed an elegant method to provide accurate area determinations, using the serial spectrometer, by a three point procedure. The parallel wavelength dispersive spectrometer (PWDS) we propose here is ideally suited for those applications.
A new facility is being constructed for the Primary Standards Laboratory at Sandia National Laboratories in Albuquerque, New Mexico. Salient features of the final design, described briefly in this paper, follow the conceptual design of 1984 to a fairly high degree. Because the facility is in process of construction, this paper is a progress report. 6 refs., 2 figs., 1 tab.
Curved and planar inversion domain boundaries (IDB) in aluminum nitride (AIN) form in sintered AIN ceramics containing oxygen, and oxygen is known to segregate to them. A number of interface models shown in Table 1, have been suggested based upon crystallographic constraints, chemical information and observed high resolution electron microscope (HREM) images. Until recently, problems with simulation of HREM images from AIN have made accurate determination of the structure of the IDB interface difficult. The aim of the present study was to use quantitative analytical electron microscopy (AEM) to determine the oxygen concentration at the IDBs, and then to compare the experimental results with calculated oxygen concentrations for each of the IDB models using a Monte Carlo electron trajectory simulation program. A match, if any, between the experimental and calculated oxygen concentrations would indicate the model which best described the IDB structure. The best match was obtained for Youngman's defect model. 14 refs., 5 figs., 3 tabs.
Plessite in iron meteorites is a two phase structure with an fcc precipitate phase in a bcc matrix. After Fe-Ni martensite forms during slow cooling, the martensite decomposition occurs at different temperatures. The morphology of the precipitates and the Ni content of both precipitate and matrix vary with the local average Ni composition of the plessite. In this study, the plessite structure of two octahedrites, Carlton and Grant, was characterized using the analytical electron microscope (AEM). The composition of the taenite precipitates in various regions of plessite which have 9 to 13 wt% and 15 to 20 wt% Ni composition were measured using an x-ray energy dispersive spectrometer (EDS) in the AEM. To understand the phase transformation processes which occurred during the plessite formation, an experimental set of Fe-Ni binary and Fe-Ni-P ternary alloys were made and analyzed also using the AEM. The alloys, which have 15 to 30 wt% Ni (0.2-0.3 wt% P for ternary alloys), were first homogenized at 1,200{degree}C and quenched to liquid nitrogen temperature to form martensite. They were then isothermally heat treated for 60 to 400 days in the temperature range from 450{degree}C to 300{degree}C. Two phase structures, which are similar to those of plessite, were formed in these alloys. The Fe-Ni phase equilibria measured in the decomposed martensite alloys can be used to explain the difference in Ni composition between precipitates in the high Ni and low Ni plessite regions. 3 refs., 2 figs.
Researchers around the world have demonstrated the effectiveness of titanium dioxide-based photocatalysis for decontaminating water containing hazardous organics and heavy metals. A great advantage of this process is that the organic is completely destroyed, leaving behind only water, carbon dioxide and dilute mineral acids. Also, the process has potential for doing two decontamination jobs at once: oxidizing organics while reducing toxic metals. As part of a program sponsored by the DOE, Sandia National Laboratories is carrying out large-scale tests to study the solar destruction of organics at realistic processing rates in addition to laboratory work aimed at determining the applicability of solar detoxification to the removal of heavy metals. In this paper, we present up-to-date results from Sandia's effort. The large-scale tests illustrate the effectiveness of solar detoxification for a variety of organics and compare measured reaction rates against published values of the rate constants for attack by aqueous hydroxyl radicals. This comparison highlights the importance of hydroxyl radical chemistry in solar detoxification processes. It is concluded that solar detoxification is only feasible for easily destroyed compounds like TCE, and PCE. The chlorinated methanes and ethanes are much more difficult to destroy and require very large solar collectors. In the second part of the paper, laboratory data are presented for a variety of different metals, including Ag, Cd, Cu, Hg, Ni, and Pt. The concentration of dissolved oxygen is one of the variables in the study. It is shown that the presence of dissolved metals can have a profound effect on organic oxidation rate, and that oxygen is not necessarily required for oxidation to occur. It is concluded that solar detoxification would be useful for removing mercury and silver but not for copper, nickel nor cadmium. 38 refs., 7 figs., 2 tabs.
Titanium dioxide (TiO{sub 2}) is a photocatalyst for solar detoxification of water containing organic contaminants such as solvents, PCB's, dioxins, pesticides, and dyes. Unfortunately, the ultraviolet (UV) energy used by TiO{sub 2} ({lambda}<400 nm) only comprises about 4% of the solar spectrum. One way of enhancing the efficiency of solar detoxification technologies is to utilize a larger portion of the solar spectrum to initiate the Tio{sub 2}- catalyzed detoxification chemistry. Metalloporphyrins strongly absorb visible and near infrared radiation. By utilization of a process called photosensitization, adsorption of these dyes onto TiO{sub 2} can enable a much broader portion of the solar spectrum to be used. Photosensitization relies upon the ability of the dye molecule to absorb more of the solar energy than bare TiO{sub 2} and to interact electronically with the TiO{sub 2} surface in such a way as to initiate TiO{sub 2}-based redox photochemistry using the dye-absorbed energy. 16 refs., 7 figs.
This document contains planned actions to correct the deficiencies identified in the Pre-Tiger Team Self-Assessment (PTTSA), January 1991, of Sandia National Laboratories (SNL -- Albuquerque, New Mexico; Tonopah, Nevada; and Kauai, Hawaii). The Self-Assessment was conducted by a Self-Assessment Working Group consisting of 19 department managers, with support from Environment, Safety, and Health (ES H) professionals, from October through December 1990. Findings from other past audits, dating back to 1985, were reviewed and compared with the PTTSA findings to determine if additional findings, key findings, or root causes were warranted. The resulting ES H Action Plan and individual planned actions were prepared by the ES H Action Plan Project Group with assistance from the Program owners/authors during February and March 1991. The plan was reviewed by SNL Management in April 1991. This document serves as a planning instrument for the Laboratories to aid in the scoping and sizing of activities related to ES H compliance for the coming five years. It will be modified as required to ensure a workload/funding balance and to address the findings resulting from the Tiger Team assessment at SNL, Albuquerque. The process of producing this document has served well to prepare SNL, Albuquerque, for the coming task of producing the required post-Tiger Team action plan document. 8 tabs.
The degree of oxidation of drops of aluminum metal was investigated parametrically for a range of melt diameters, relative melt-water velocities, melt temperatures, water temperatures, and ambient pressures using a combined film boiling-metal oxidation model. The model predictions of degree of oxidation were then compared to small-scale experiments involving molten drops of aluminum metal. The conclusions were, first, that for the range of melt temperatures and diameters considered, if an oxide layer forms and blankets the molten aluminum, then no significant oxidation occurs, in agreement with the results of experiments performed under quiescent, steady-state conditions. Second, comparing model results to data from single drop fragmentation experiments indicates that under the transient conditions occurring during rapid fragmentation, the oxide layer is disturbed and oxidation rates are limited primarily by the amount of steam available at the melt surface. Third, for a range of parameters, the heat gain in the melt drop from the oxidation reaction can exceed the heat loss to the surroundings, resulting in thermal runaway and ignition of the melt. This effect is observed experimentally as a threshold temperature effect, predicted to be about 1100 K for the initial single drop study, and between 1500 K and 1600 K for the single drop experiments. 7 refs., 2 tabs.
It is shown that preirradiation channel-mobility and 1/f-noise measurements can reveal a great deal about postirradiation interface- and oxide-trap charge buildup in MOS transistors. A model is developed to explain the observed correlations. 10 refs., 4 figs.
The effectiveness of hardening the SA3300 against SEU using design and design-plus-resistor approaches is presented. The full performance and SEU tolerance requirements are met using R{sub fb} {le} 160 k{Omega}. Lumped-parameter circuit simulations are used to analyze results. 10 refs., 5 figs.
Changes in brine and gas permeability of rock salt as a result of nearby excavation (mine-by) have been measured from the underground workings of the WIPP facility. Prior to the mine-by, the formation responds as a porous medium with a very low brine permeability, a significant pore (brine) pressure and no measurable gas permeability. The mine-by excavation creates a dilated, partially saturated zone in the immediate vicinity of the excavation with an increased permeability to brine and a measurable permeability to gas. The changes in hydrologic properties are discussed in the context of pore structure changes.
The chemical synthesis of advanced ceramic and glass materials by the sol-gel process has become an area of increasing activity in the field of material science. The sol-gel process provides a means to prepare homogeneous, high purity materials with tailored chemical and physical properties. This paper surveyed the nuclear magnetic resonance (NMR) studies of silicon-based sol-gel kinetics. A review of the various models which have been used to analyze the chemical kinetics of various sol-gel systems was presented. The utility of NMR spectroscopy was demonstrated in investigating the influence that various reaction conditions have on the reaction pathways by which sol-gel derived materials are synthesized. By observing in a direct fashion the chemical pathway of the sol-gel, it is often possible to relate the final properties of the material to the formulation and reaction conditions of the sol-gel. The study of reaction kinetics by NMR is expected to play an increasingly important role in understanding sol-gel processing and material properties. 15 refs. (DP)
For several years Phillips Petroleum Company has been waterflooding portions of the Ekofisk Field reservoir for purposes of enhanced oil recovery. Boreholes drilled in waterflooded portions of the reservoir have encountered poor core recoveries and highly fractured rock (poor core recoveries and highly fractured zones were not uncommon in the Ekofisk reservoir before waterflooding, however). Results of laboratory compression tests designed to simulate production-related compaction and subsequent waterflooding indicate that injection pressures currently used to inject seawater into the reservoir are high enough to induce shear failure in high porosity reservoir chalks. A model of chalk deformation explains brittle failure of chalk that has been subjected to stresses well in excess of yield stress.
The Sandia National Laboratories Pre-Tiger Team Self-Assessment Report contains an introduction that describes the three sites in Albuquerque, New Mexico, Kauai, Hawaii, and Tonopah, Nevada, and the activities associated therewith. The self-assessment was performed October 1990 through December 1990. The paper discusses key findings and root causes associated with problem areas; environmental protection assessment with respect to the Clean Air Act, Clean Water Act, Comprehensive Environmental Response, Compensation, and Liability Act and the Superfund amendments, Resource Conservation and Recovery Act; and other regulatory documents; safety and health assessment with respect to organization administration, quality assurance, maintenance, training, emergency preparedness, nuclear criticality safety, security/safety interface, transportation, radiation protection, occupational safety, and associated regulations; and management practices assessment. 5 figs. (MHB)
Large two- and three-dimensional simulations of shock wave physics problems constitute a major expense in ongoing research efforts at Sandia National Laboratories. Massively parallel computing may provide a solution. A simplified version of the production hydrocode CTH, in current use at Sandia National Laboratories, has been successfully developed for the Connection Machine. The parallel version, named PCTH, solves problems in multi-fluid shock wave physics. The development of the Connection Machine code is described and initial performance statistics are presented. These are compared with similar results for the CRAY Y-MP and nCUBE2. 7 refs., 3 figs., 1 tab.
The durability of a carbon-carbon composite, Aerolor A05, X-point divertor dump plate to thermal fatigue was evaluated for the Joint European Torus (JET) at Sandia's Plasma Material Test Facility. Of primary interest was the effect of thermal cycling on the carbon-carbon threads of the bolted attachment scheme for the Aerolor X-point divertor. This report describes the testing performed at the Ion Beam Test System and the test and analysis results obtained in support of this effort. After completing 1000 thermal cycles, where the surface temperature of the 8 cm by 8 cm by 2.3 cm Aerolor tile reached 2200{degree}C during a 10 s, 500 W/cm{sup 2} pulse, the tile survived without any noticeable damage. Post test inspection of the carbon-carbon threads showed only minor wear and no signs of significant damage. Thermal modeling of the test article using the ABAQUS finite element code agreed very well with experimental results. The thermal creep experienced by the M-12 stainless steel bolt during ion beam testing will not be expected to occur during normal operations in JET because of the longer cycle times between the thermal events. Finite element analysis indicates that the longer cycle times at the JET will reduce the peak temperatures in the vicinity of the bolt and bolt insert below the level at which thermal creep would occur. An additional margin of safety could be obtained by using Inconel or Nimonic fasteners. Overall, the performance of the bolted divertor design to thermal fatigue was acceptable. 12 figs., 2 tabs.
An electromagnetic measurement system (EMMS) was designed and constructed to provide essential data relating to electromagnetic compatibility (EMC) of modern weapons carried on military aircraft. This system measures the equivalent plane wave electric and magnetic fields impinging on a weapon's exterior surface arising from electromagnetic radiators on board host or nearby aircraft. To relate practical sensor responses to specified equivalent plane wave EMC field levels, a modern weapon shape was used as the primary sensor element which responds with a simple dipole antenna response at the lower frequencies and is instrumented with local skin current sensors. At higher frequencies, the locally induced currents can be related to the incident fields by simple scattering theory. Finally, an error analysis that catalogs all measurement path elements was performed to provide an error bound on the equivalent free electric field measurements reported by the EMMS. 6 refs., 9 figs.
A Low Altitude High Speed Cargo (LAHSC) parachute is being developed for deployment at velocities up to 250 knots at 300 ft altitude. The LAHSC parachute will decelerate and turnover a load to a 40 to 60 ft/sec vertical velocity at first vertical at approximately 30 ft AGL. The acceleration limit is 5 g's. Main chute cargo extraction will be necessary. A single parachute will be utilized for a 7500 lb load, and clusters will be used for larger loads. The 64-gore, 70-ft-dia parachute has a ring-slot/solid construction with a flare at the skirt to aid the inflation. This paper describes the parachute, the design process and testing to date. Model parachutes have been tested in wind tunnels and in free flight. A single full-scale parachute has been tested at low speeds with conventional load extraction, and with a vertical trajectory at deployment. 5 refs., 18 figs., 3 tabs.
High-speed water-entry is a very complex, dynamic process. As a first attempt at modeling the process, a numerical solution was developed at Sandia National Laboratories for predicting the forces and moments acting on a body with a steady supercavity, that is, a cavity which extends beyond the base of the body. The solution is limited to supercavities on slender, axisymmetric bodies at small angles of attack. Limited data were available with which to benchmark the axial force predictions at zero angle of attack. Even less data were available with which to benchmark the pitching moment and normal force predictions at nonzero angles of attack. A water tunnel test was conducted to obtain force and moment data on a slender shape. This test produced limited data because of waterproofing problems with the balance. A new balance was designed and a second water tunnel test was conducted at Tracor Hydronautics, Inc. This paper describes the numerical solution, the experimental equipment and test procedures, and the results of the second test. 8 refs., 11 figs.
Micromachining is a rapidly growing field which allows for the fabrication of extremely small sensors and actuators using many of the techniques common to microelectronics. Two methods are commonly used: bulk micromachining, which involves the sculpting of single crystal silicon, and surface micromachining, which uses etched thin films that have been deposited on the substrate. Sensors are the primary commercial application, but microactuators are being actively researched at several laboratories and universities. Sandia National Laboratories is pursuing applications of both bulk and surface micromachining for silicon microsensors, microactuators, and high-performance, silicon packages for microelectronics. 3 figs.
This is an extension of two previous analytical studies to investigate a technique for generating high frequency, high amplitude vibration environments. These environments are created using a device attached to a common vibration exciter that permits multiple metal on metal impacts driving a test surface. These analytical studies predicted that test environments with an energy content exceeding 10 kHz could be achieved using sinusoidal and random shaker excitations. The analysis predicted that chaotic vibrations yielding random like test environments could be generated from sinusoidal inputs. In this study, a much simplified version of the proposed system was fabricated and tested in the laboratory. Experimental measurements demonstrate that even this simplified system, utilizing a single impacting object, can generate environments on the test surface with significant frequency content in excess of 40 kHz. Results for sinusoidal shaker inputs tuned to create chaotic impact response are shown along with the responses due to random vibration shaker inputs. The experiments and results are discussed. 4 refs., 5 figs.
Sandia National Laboratories has utilized pool fires for over thirty years to subject military components, weapon mockups and hazardous material shipping containers to postulated transportation accident environments. Most of the tests have been performed in either open pools or wind shielded facilities with little control of visible smoke emissions. Because of the increased sensitivity of environmental issues and because wind generates the biggest uncontrollable effect on the thermal environment in open pool fires, enclosed test facilities with reduced visible emissions have been developed. The facilities are basically water cooled enclosures fitted with controlled air supply systems and high temperature afterburners. The purpose of this paper is to present our experience with both open and enclosed fires. In the first section, a review of the fire test facilities is given. A following section presents a mathematical model behind our approach to characterizing the fire environment. In the last section, data from open and closed fires are compared.
Research programs from Sandia Laboratory in Materials Science are briefly presented. Significant accomplishments include: preparation of Tl superconductors under equilibrium conditions, development of force-feedback sensor for interfacial force microscope, predictive model of hydrogen interactions in silicon dioxide on silicon, layer-by-layer sputtering of Si (001), oscillatory As{sub 4} surface reaction rates during molecular beam epitaxy of AlAs, GaAs and InAs, the effects of interfacial strain on the band offsets of lattice matched III-V semiconductor, a new mechanism for surface diffusion, solid solution effects in Tl-containing superconductors, record high superconducting transitions for organic materials, atomic vibrations in boron carbides and a method for studying radical/surface reactions in chemical vapor deposition (CVD).
Recent government actions to eliminate Chlorofluorocarbons (CFCs) and Chlorinated Hydrocarbons (CHCs) from the industrial environment require the evaluation of new cleaning solvents and processes. High reliability printed wiring board (PWB) assemblies require cleaning to remove process materials which could lead to corrosion or degradation of the electrical performance of the boards. In the past, CFCs have been used extensively for PWB cleaning purposes. Concerns about CFC emissions and their effect on ozone depletion in the atmosphere, greater demands on cleaning systems, and the availability of alternative cleaning methods are requiring manufacturers of electronic assemblies to reconsider the choice of cleaning methods. We will review some of the presently available cleaning solvents and discuss the results of our work using a terpene-based cleaner. 5 refs., 4 figs.
The Recirculating Linear Accelerator (RLA) is returning to operation with a new electron beam injector and a modified accelerating cavity. Upon completion of our experimental program the RLA will capture the injected beam on an IFR guiding plasma channel in either a spiral or a closed racetrack drift tube. The relativistic beam will be efficiently recirculated for up to four passes through two or more accelerating cavities, in phase with the ringing cavity voltage waveforms, and thereby increased in energy to 10 MeV before being extracted. The inductively isolated four-stage injector was designed to produce beam parameters of 4 MeV, 10--20 kA, and 40--55 ns FWHM. The three-line radial cavity is being modified to improve the 1-MV accelerating voltage pulse shape while an advanced cavity design study is in progress. The actual versus predicted pulsed-power performance of the RLA injector and cavity and the associated driving hardware will be discussed in this paper.
Last year at the HP82000 Users Group Meeting, Sandia National Laboratories gave a presentation on I{sub DDQ} testing. This year, we will present some advances on this testing including DUT board fixturing, external DC PMU measurement, and automatic IDD-All circuit calibration. This paper is geared more toward implementation than theory, with results presented from Sandia tests. After a brief summary I{sub DDQ} theory and testing concepts, we will describe how the break (hold state) vector and data formatting present a test vector generation concern for the HP82000. We than discuss fixturing of the DUT board for both types of I{sub DDQ} measurement, and how the continuity test and test vector generation must be taken into account. Results of a test including continuity, IDD-All and I{sub DDQ} Value measurements will be shown. Next, measurement of low current using an external PMU is discussed, including noise considerations, implementation and some test results showing nA-range measurements. We then present a method for automatic calibration of the IDD-All analog comparator circuit using RM BASIC on the HP82000, with implementation and measurement results. Finally, future directions for research in this area will be explored. 14 refs., 16 figs.
Proceedings - IEEE International Conference on Robotics and Automation
Hwang, Yong K.
Path planning among movable obstacles is a practical problem that is in need of a solution. An efficient heuristic algorithm is presented that uses a generate-and-test paradigm: a good candidate path is hypothesized by a global planner and subsequently verified by a local planner. In the process of formalizing the problem, a technique for modeling object interactions through contact is presented. The algorithm has been tested on a variety of examples, and was able to generate solutions within 10 s on a 17-MIPS Sun Sparc workstation.
CEPXS/ONELD is the only discrete ordinates code capable of modelling the fully-coupled electron-photon cascade at high energies. Quantities that are related to the particle flux such as dose and charge deposition can readily be obtained. This deterministic code is much faster than comparable Monte Carlo codes. The unique adjoint transport capability of CEPXS/ONELD also enables response functions to be readily calculated. Version 2.0 of the CEPXS/ONELD code package has been designed to allow users who are not expert in discrete ordinates methods to fully exploit the code's capabilities. 14 refs., 15 figs.
With the current trends towards miniaturization, high performance, high quality and cost competiveness, the electrodeposition process has become an important manufacturing technology in many new microelectronic applications. Gold electrodeposition plays an increasing role in processes that require this noble metal. Added to these trends is the continuing and increasing emphasis on manufacturing processes which are less damaging to the environment and potentially less hazardous to the operator and personnel in the vicinity of the operation. The present standard gold plating solutions are based on cyanide salts and are considered acutely hazardous solutions. The trend away from their use is gaining momentum as new non-hazardous gold plating solutions and manufacturing processes making use of them are developed. 2 refs.
A performance assessment methodology has been developed for use by the US Nuclear Regulatory Commission in evaluating license applications for low-level waste disposal facilities. This report provides detailed guidance on input and output procedures for the computer codes recommended for use in the methodology. Seven sample problems are provided for various aspects of a performance assessment analysis of a simple hypothetical conceptual model. When combined, these sample problems demonstrate how the methodology is used to produce a dose history for the site under normal conditions, and to demonstrate an analysis of an intruder scenario. 20 refs., 26 figs., 4 tabs.
Results of calculations performed with MELCOR and HECTR in support of the NUREG-1150 study are presented in this report. The analyses examined a wide range of issues. The analyses included integral calculations covering an entire accident sequence, as well as calculations that addressed specific issues that could affect several accident sequences. The results of the analyses for Grand Gulf, Peach Bottom, LaSalle, and Sequoyah are described, and the major conclusions are summarized.
Electromagnetic coupling to electronic components or subsystems is a concern in modern system design. Undesired coupling can cause interference or, in the extreme, system upset. To be able to characterize the coupling is an important step to understanding the limitations on system performance. Often the approach is taken to shield the electronic equipment inside some kind of enclosure. However, there are usually inadvertent cracks or bowing at mechanical interfaces. These gaps are apparent slot apertures. An equivalent antenna/local transmission line model for narrow slot apertures with depth including losses has been developed. It may be applied tortuous paths and hence may be used to model practical situations. This model has been previously verified by measuring the coupling through narrow slot apertures with varying width and depth. These measurements were performed for brass slots radiating into a half-space. The results were in good agreement with the model of Warne and Chen. The models, as well as the measurements showed that for very narrow slots the wall loss becomesdominant -- it has been demonstrated that the inclusion of loss is important in making realistic coupling estimates in practical configurations. This paper presents results showing the effects of varying conductivity and surface preparations for half-space coupling as well as different loadings of the narrow slot apertures. The coupling through narrow slot apertures having depth was measured for a variety of resonant cavity loadings. The loadings were chosen such that the cavity resonant frequencies were above, near and below the resonant peak of the half-space coupling curve. Measurements were made in the 2--4 GHz band with vertical polarization. 3 refs., 6 figs., 1 tab.
The solidification behavior of Custom Age 625 PLUS{reg sign} is examined using an integrated analytical approach. Like its predecessors, Alloys 625 and 718, the solidification behavior of this new alloy is dominated by the presence and segregation of Nb, which gives rise to a {gamma}/Laves terminal solidification constituent. 8 refs., 5 figs., 2 tabs.
Iterative, annual performance-assessment calculations are being performed for the Waste Isolation Pilot Plant (WIPP), a planned underground repository in southeastern New Mexico, USA for the disposal of transuranic waste. The performance-assessment calculations estimate the long-term radionuclide releases from the disposal system to the accessible environment. Because direct experimental data in some areas are presently of insufficient quantity to form the basis for the required distributions. Expert judgment was used to estimate the concentrations of specific radionuclides in a brine exiting a repository room or drift as it migrates up an intruding borehole, and also the distribution coefficients that describe the retardation of radionuclides in the overlying Culebra Dolomite. The variables representing these concentrations and coefficients have been shown by 1990 sensitivity analyses to be among the set of parameters making the greatest contribution to the uncertainty in WIPP performance-assessment predictions. Utilizing available information, the experts (one expert panel addressed concentrations and a second panel addressed retardation) developed an understanding of the problem and were formally elicited to obtain probability distributions that characterize the uncertainty in fixed, but unknown, quantities. The probability distributions developed by the experts are being incorporated into the 1991 performance-assessment calculations. 16 refs., 4 tabs.
Segmentation is a process of separating objects of interest from their background or from other objects in an image. Without a suitable segmentation scheme, it is very difficult to detect contraband in X-rays images. In this paper, a Probabilistic Relaxation Labeling (PRL) segmentation scheme is presented and compared with other segmentation methods. PRL segmentation is an interative algorithm that labels each pixel in an image by cooperative use of two information sources: the pixel probability and the degree of certainty of its probability supported by the neighboring pixels. The practical implementation and results of the PRL segmentation on X-ray baggage images are also discussed and compared with other segmentation methods. 13 refs., 12 figs.
This investigation describes how a statistically designed experiment can be useful to characterize the relationship between a fundamental material property such as the glass transition temperature, Tg, and various processing parameters, e.g. composition, cure time, and temperature. To illustrate, formulation weighing errors can have a dramatic affect on material properties such as thermal, mechanical, and electrical properties. The glass transition temperature was selected for monitoring because it represents the materials state of cure and it is relatively easy to determine. Specifically, EPON 828 systems cured with diethanolamine and Shell Z, respectively, were investigated plus a mixture of the latter that employed aluminum oxide as a filler. This investigation showed that Tg changed very little with cure temperature in the DEA system compared to Shell Z, whereas the latter system appeared to display synergistic effects contrary to the DEA system. In the filled formulation, loading level had very little effect on Tg. The significance of this study is that the relationship between Tg, the composition and processing factors can be used to help diagnose the cause of misprocessed material. 2 refs., 11 figs., 3 tabs.
The detonability of hydrogen-air-diluent mixtures was investigated experimentally in the 0.43 m diameter, 13.1 m long Heated Detonation Tube (HDT) for the effects of variations in hydrogen and diluent concentration, initial pressure, and initial temperature. The data were correlated using a ZND chemical kinetics model. The detonation limits in the HDT were obtained experimentally for lean and rich hydrogen-air mixtures and stoichiometric hydrogen-air-steam mixtures. The addition of a diluent, such as steam or carbon dioxide, increases the detonation cell width for all mixtures. In general, an increase in the initial pressure or temperature produces a decrease in the cell width. In the HDT, the detonable range of hydrogen in a hydrogen-air mixture initially at 1 atm pressure is between 11.6 percent and 74.9 percent for mixtures at 20°C, and 9.4 percent and 76.9 percent for mixtures at 100°C. The detonation limit is between 38.8 percent and 40.5 percent steam for a stoichiometric hydrogen-air-steam mixture initially at 100°C and 1 atm. The detonation limit is between 29.6 percent and 31.9 percent steam for a stoichiometric hydrogen-air-steam mixture for the case where hydrogen and steam are added to air initially at 20{degree}C and 1 atm resulting in a final predetonation mixture temperature and pressure of approximately 100°C and 2.6 atm, respectively.
Currently, over 90% of the world's large-scale solar electric energy is generated with concentrating solar thermal power plants. Such plants have the potential to meet many of the world's future energy needs. Research efforts are generally focused on generating electricity, though a variety of other applications are being pursued. Today, the technology for using solar thermal energy is well developed, cost competitive, and in many cases, ready for widespread application. The current state of each of the solar thermal technologies and their applications is reviewed, and recommendations for increasing their use are presented. The technologies reviewed in detail are: parabolic trough systems, central tower systems, and parabolic dish systems. 20 refs., 1 fig., 1 tab.
TRANSNET is a compilation of risk and systems analysis codes, routing and cost models and related data that address hazardous and radioactive materials transportation. TRANSNET is the acronym assigned to this system of models and associated data which reside on a dedicated MicroVAX 3800. After obtaining a password, users may access TRANSNET with a modem-equipped personal computer. TRANSNET was developed by Sandia National Laboratories (SNL) under the sponsorship of the United States Department of Energy (DOE) Office of Defense Programs (subsequently reorganized to the Office of Environmental Restoration and Waste Management). The goals of the TRANSNET system are to speed transfer of technology and data to qualified users by permitting access to the most comprehensive and up-to-date transportation risk and systems analysis models and associated databases. 13 refs.
Relational databases have many advantages over former hierarchical and network systems -- the most important advantage is their ease of modification. This leads designers to a new approach, which we at our company are finding very useful in building an information system of corporate-wide shared data. This approach is a phased bottom-up design and application development which is supported by an information modeling method called NIAM (Nijssen's Information Analysis Method). NIAM is not well known in the USA, but is widely used in Europe. An introduction to the NIAM approach and its advantages will be followed by examples of models and their corresponding relational database designs that have been developed in step-wise fashion at our company. Since NIAM algorithms yield tables in fifth normal form, our relational systems are implemented for optimum update capabilities and enforceable referential integrity. 4 refs., 6 figs.
In FY90 important milestones from past Administrative Information Systems (AIS) plans were realized. The first phase of the Payroll migration was implemented early in the year. This event signified the completion of a major migration milestone and the transition of the Laboratory Information Systems (LIS) machine to a production environment. The Access Clearance System (A CS) system and several early deliverables from other migration projects were also implemented during the year. FY91 promises to be another challenging year for those involved with administrative information systems. Aggressive schedules are in effect for the migration projects; the Financial Migration, Human Resources (HR) Migration, and Integrated Procurement System Replacement (IPS/R) efforts will deliver major system components this year. The administrative computing consolidation is underway and will be completed early in FY91. Consolidating computing hardware resources will provide adequate resources and better systems support for the entire AIS community.
In this paper, we review correlation filters as an approach to pattern recognition with a special emphasis on the consequences of normalizing the correlation to achieve intensity invariance. Intensity invariance is effected using the Cauchy-Schwarz inequality to normalize the correlation integral. We discuss the implications of this criterion for the application of correlation filters to the pattern recognition problem. It is shown that normalized phase-only and synthetic discriminate functions do not provide the recognition/discrimination obtained with the classical matched filter. 34 refs., 5 figs.
In keeping with the philosophy of the external events analyses for NUREG-1150, which are intended to be smart probabilistic risk assessments (PRAs) making full use of all insights gained during the past 10 years of development in risk assessment methodologies, the Savannah River K-Reactor fire analysis was performed using newly developed and simplified methods. These methods have been under development at Sandia National Laboratories under sponsorship of the Nuclear Regulatory Commission (NRC) Division of Risk Assessment as part of the Dependent Failure Methodology Development Program. A detailed screening analysis was performed which showed most plant areas had a negligible contribution to fire-induced core damage frequency. Detailed analysis of the fire risk resulted in a total (mean) core damage frequency of 1.35E-7 per year. 18 refs., 12 figs., 17 tabs.
The project comprises the development of concentrating solar collectors, heliostats and dishes, and the development of optical materials. Because the solar concentrator represents from 40 to 60% of the cost of a solar thermal electric system, the continued development of high-performance concentrators is very important to the commercial viability of these systems. The project is currently testing two large area heliostats, the SPECO 200 m{sup 2} heliostat and the ATS 150 m{sup 2} heliostat and also trying to reduce the cost of the heliostats through the development of stretched-membrane heliostats. Stretched-membrane heliostats are made by attaching thin metal membranes to the two sides of a circular, metal ring. A slight vacuum in the plenum between the two membranes is used to focus the heliostat. The optical surface is provided by a silver-acrylic film, ECP 305. A prototype 100 m{sup 2} commercial unit has been built and is currently being tested. Parabolic dish concentrators are under development for use on dish-Stirling electric systems. The state-of-the-art dish is the McDAC/SCE faceted glass concentrator. Because of the success of stretched-membrane technology for heliostats, the project applied the technology to parabolic dish development and is currently designing a near-term, faceted, stretched-membrane dish. The current thrust of the program in optical materials development is the development of a low-cost, high-performance, silver-acrylic film. 3M's ECP 305 has demonstrated substantial improvement over previous films in its resistance to corrosion, longer life. An experimental film, developed at SERI, has promise for further improving the lifetime of the ECP 305. The project is currently investigating solutions to the problem of separation between the silver and acrylic layers of the film in the presence of water.
A technique to localize errors between two modal models is presented. Mode shape difference are calculated from each model. A global comparison of the ratios of these corresponding differences is used to identify the physical locations on the structure where stiffness differences exist between the two models. Some of the strengths and limitations of the technique are illustrated using the mode shapes of two similar finite element models with a known stiffness difference. The technique is then applied to a two link robot arm for which a finite element model exists and a modal test has been conducted. The results of the error localization aid the selection of physical parameters to be updated in the finite element model. Sensitivity methods are used to correlate the finite element model to the modal test. The results of the correlation are presented. 5 refs., 3 figs., 3 tabs.
Sandia National Laboratories is conducting performance assessments for the United States Department of Energy to use in evaluating compliance of the Waste Isolation Pilot Plant with EPA 40 CFR 191, Subpart B. Performance assessment is an iterative process that will lead to final compliance evaluation in 1994 or later. Monte Carlo simulations examine modeling system sensitivity to the probability of intrusion and uncertainty in the transport model for the overlying water-bearing unit. Simulations of two-phase (gas and brine) flow indicate gas generation may substantially reduce brine saturation in the waste, limiting radionuclide transport. All results are preliminary and are not suitable for evaluating compliance. Results suggest, however, that compliance can be achieved.
This paper will provide an overview of cleaning qualifications used in a variety of industries: from small-scale manufacturer's of precision-machined products to large-scale manufacturer's of electronics (printed wiring boards and surface mount technology) and microelectronics. Cleanliness testing techniques used in the production of precision-machined products, will be described. The on-going DOD program to obtain high-reliability electronics, through the use of military specifications for cleaning and cleanliness levels, will be reviewed. In addition, the continually changing cleanroom/materials standards of the microelectronics industry will be discussed. Finally, we will speculate on the role that new and improved analytical techniques and sensor technologies will play in the factories of the future. 4 refs., 1 tab.
Ray paths and focal lengths are derived to fourth order for a nuclear-reactor wall-pumped gas laser. Ray paths in the laser gain cell are shown to be nearly random for a long gain region. Focal lengths calculated from the ray paths exiting the laser are shown to oscillate between {plus minus} {infinity} during pumping. The use of stimulated Brillouin scattering as a means for beam clean-up is discussed with the conclusion that the phase conjugated beam would cycle on and off as the ray paths and focal lengths oscillate between extremes. The parameters determining this cycling effect and its characteristics are also derived. 17 refs., 11 figs., 1 tab.
MELCOR is a fully integrated, engineering-level computer code that models the progression of severe accidents in light water reactor nuclear power plants. MELCOR is being developed at Sandia National Laboratories for the US Nuclear Regulatory Commission as a second-generation plant risk assessment tool and the successor to the Source Term Code Package. The entire spectrum of severe accident phenomena, including reactor coolant system and containment thermal-hydraulic response, core heatup, degradation and relocation, and fission product release and transport, is treated in MELCOR in a unified framework for both boiling water reactors and pressurized water reactors. MELCOR has been especially designed to facilitate sensitivity and uncertainty analyses. Its current uses include estimation of severe accident source terms and their sensitivities and uncertainties in a variety of applications. This report is a summary of MELCOR 1.8.0, the code version released in March 1989. Condensed information is presented on its developmental history, structure, modeling features and capabilities, verification and validation, and quality assurance. Detailed documentation on these aspects of MELCOR, including users' guides, reference manuals, programmers' guides, and assessment and application reports, is available in draft form and is distributed to MELCOR users.
Experimental tests on the Annular Core Research Reactor have confirmed that the Three-Bean-Salad'' control algorithm based on the Pontryagin maximum principle can change the power of a nuclear reactor many decades with a very fast startup rate and minimal overshoot. The paper describes the results of simulations and operations up to 25 MW and 87 decades per minute. 3 refs., 4 figs., 1 tab.
The spherical element computer code DMC (Distinct Motion Code) used to model rock motion resulting from blasting has been enhanced to allow routine computer simulations of bench blasting. The enhancements required for bench blast simulation include: (1) modifying the gas flow portion of DMC, (2) adding a new explosive gas equation of state capability, (3) modifying the porosity calculation, and (4) accounting for blastwell spacing parallel to the face. A parametric study performed with DMC shows logical variation of the face velocity as burden, spacing, blastwell diameter and explosive type are varied. These additions represent a significant advance in the capability of DMC which will not only aid in understanding the physics involved in blasting but will also become a blast design tool. 8 refs., 7 figs., 1 tab.
Nd:YAG laser cleaning of metal oxides from 304L stainless steel surfaces has been characterized. Thin chromium oxide films can be completely removed from the surface using a single 10 nsec pulse of laser radiation with an average surface irradiance greater than 120 MW/cm{sup 2}. Laser etching of thicker iron oxide films exhibit a self-limiting effect that prevents overetching into the stainless steel substrate. 8 figs.
Electron-Beam (EBeam) melting furnaces are routine used to minimize the occurrence of second-phase particles in the processing of segregation-sensitive alloys. As one part of the process, a circulating electron beam impinges the surface of a crucible melt pool to help control the shape of the solidification front below. By modeling melt pool hydrodynamics, heat transfer, and the shape of solidification boundaries, we plan to optimize the dwell pattern of the beam so that the material solidifies with a composition as spatially homogeneous as possible. Both two- and three-dimensional models are being pursued with FIDAP 5.02, the former serving as a test bed for various degrees of model sophistication. A heat flux distribution is specified on the top of the domain to simulate the EBeam dwell pattern. In two dimensions it is found that an inertially-driven recirculation in the melt pool interacts with a counter-rotating buoyancy-driven recirculation, and that both recirculations are influenced heavily by surface tension gradients on the melt-pool surface. In three dimensions the inertial cell decays quickly with distance from the position of the inlet stream, causing the fluid to precess the crucible. Ingot macrosegregation patterns for a U-6 wt. % Nb alloy are calculated with the Flemings-Mehrabian equation of solute redistribution; the sensitivity of these patterns to EBeam dwell pattern is explored.
Proceedings - IEEE International Conference on Robotics and Automation
Novak, J.L.; Wiczer, J.J.
A high-resolution capacitive image sensing technique for measuring edge and surface profiles during manufacturing processes has been invented. A prototype device utilizing this technique consists of two 500-μm-diameter electrodes fabricated on a printed circuit board with a 250-μm gap between them. As the device is mechanically scanned over the workpiece, the spatial variations in the edge or surface to be measured interfere with an electric field imposed between the electrodes, altering the mutual capacitance. The sensor functions as a near-field proximity sensor producing range images of surface imperfections. This sensor has been used in applications requiring a preview image of burns on the edge of a machined part and other processes requiring an inspection image after automated deburring operations.
Proceedings - IEEE International Conference on Robotics and Automation
Stansfield, S.A.
A series of haptic exploratory procedures (EPs) implemented for a multifingered, articulated, sensate robot hand is discussed. These EPs are designed to extract specific tactile and kinesthetic information from an object via their purposive invocation by an intelligent robotic system. Taken together, they form an active robotic touch perception system. This system utilizes a PUMA 560 robot arm, a JPL/Stanford robot hand with joint torque sensing in the fingers, a wrist force/torque sensor, and a 256-element spatially resolved fingertip tactile array. The EPs are described, and experimental results are given.
The LIFE2 computer code is a fatique/fracture analysis code that is specialized to the analysis of wind turbine components. The numerical formulation of the code uses a series of cycle count matrices to describe the cyclic stress states imposed upon the turbine. In this formulation, each stress cycle is counted or binsed'' according to the magnitude of its mean stress and alternating stress components and by the operating condition of the turbine. A set of numerical algorithms has been incorporated into the LIFE2 code. These algorithms determine the cycle count matrices for a turbine component using stress-time histories of the imposed stress states. This paper describes the design decisions that were made and explains the implementation of these algorithms using Fortran 77. 7 refs., 7 figs.
The CONTAIN quality assurance program follows a strict set of procedures designed to ensure the integrity of the code, to avoid errors in the code, and to prolong the life of the code. The code itself is maintained under a code-configuration control system that provides a historical record of changes. All changes are incorporated using an update processor that allows separate identification of improvements made to each successive code version. Code modifications and improvements are formally reviewed and checked. An exhaustive, multilevel test program validates the theory and implementation of all codes changes through assessment calculations that compare the code-predicted results to standard handbooks of idealized test cases. A document trail and archive establish the problems solved by the software, the verification and validation of the software, software changes and subsequent reverification and revalidation, and the tracking of software problems and actions taken to resolve those problems. This document describes in detail the CONTAIN quality assurance procedures.
The 10-MW{sub e} Solar One Pilot Plant was the world's largest solar central receiver power plant. During its power production years it delivered over 37,000 MWhrs (net) to the utility grid. In this type of electric power generating plant, large sun-tracking mirrors called heliostats reflect and concentrate sunlight onto a receiver mounted on top a of a tower. The receiver transforms the solar energy into thermal energy that heats water, turning it into superheated steam that drives a turbine to generate electricity. The Solar One Pilot Plant successfully demonstrated the feasibility of generating electricity with a solar central receiver power plant. During the initial 2 years the plant was tested and 4 years the plant was operated as a power plant, a great deal of data was collected relating to the efficiency and reliability of the plant's various systems. This paper summarizes these statistics and compares them to goals developed by the US Department of Energy. Based on this comparison, improvements in the design and operation of future central receiver plants are recommended. Research at Sandia National Laboratories and the US utility industry suggests that the next generation of central receiver power plants will use a molten salt heat transfer fluid rather than water/steam. Sandia has recently completed the development of the hardware needed in a molten salt power plant. Use of this new technology is expected to solve many of the performance problems encountered at Solar One. Projections for the energy costs from these future central receiver plants are also presented. For reference, these projections are compared to the current energy costs from the SEGS parabolic trough plants now operating in Southern California.
The results of the first year of an evaluation of charge controllers for stand-alone photovoltaic (PV) systems are presented. The objectives of the test program are to positively influence the development of battery charge controllers for stand-alone PV applications and to develop design and application criteria that will improve PV system reliability and battery performance. Future goals are to expand the evaluation program to include various battery technologies and controller algorithms. Also, the information is being communicated to manufacturers to aid in the design of more effective and reliable charge controllers for PV systems. Eight different models of small (nominal 10 amp) charge controllers are being subjected to a comprehensive evaluation. These evaluations include operational tests in identical stand-alone PV systems and environmental and electrical cycling tests. Selected custom tests are also performed on the controllers to determine the response to transients, installation requirements and system design compatibilities. Data presented in this paper include measured electrical characteristics of the controllers, temperature effects on set points, and operational performance in PV systems both in the lab and in the field. A comparison is presented for four different charge controller algorithms which include array-shunt, series-interrupting, series-linear constant-voltage and series-linear-multistep constant-current. 9 refs., 11 figs., 2 tabs.
SAS software is being used to analyze product test data stored in an INGRES relational database. The database has been implemented at Allied-Signal in Kansas City on a Digital Equipment Corporation (DEC) VAX computer. The INGRES application development has been a joint project between Sandia National Laboratories and Allied-Signal. Application screens have been developed so that the user can query the database for selected data. Fourth generation language procedures are used to retrieve all data requested. FORTRAN and VAX/VMS DCL (DIGITAL Control Language) procedures are invoked from the application to create SAS data sets and dynamically build SAS programs that are executed to build custom reports or graphically display the retrieved test data along with control and specification limits. A retrieval screen has also been developed which invokes SAS software to calculate the mean and standard deviation of the retrieved data. These parameters are passed back into the application for display and may then be used as an aid in setting new control limits for future test runs. Screens have been developed to provide an interface for the user to select from a library of SAS programs, edit the selected program, and run the program with a user-defined SAS data set as input. This paper will give a brief description of the application screens and provide details of how information is passed between the application and SAS programs.
I was asked to write a database application that would be user friendly to the extent that a minimum amount of learning would be required of the user to run the application, yet it would be flexible enough to gather the data in various combinations. Writing SELECT'' or RETRIEVE'' queries required to much initial training. Hard coding queries into the application meant the users could not pick columns or create contraints. I decided to compromise somewhat, requiring my users to learn how to manipulate VIFRED menus and by doing so they could pick any combination of columns for output, select any column variable to sort on, and impose simple, yet practical constaints on the data, all this possible at run time. This handout contains copies of the VIFRED menus, the help message for imposing constraints, output from sample retrievals, descriptions of the relational tables needed to implement the methodology, and the computer coding of the actual retrieval construction.
Burnup credit is the application of the effects of fuel burnup to nuclear criticality design. When burnup credit is considered in the design of storage facilities and transportation casks for spent fuel, the objectives are to reduce the requirements for storage space and to increase the payload of casks with acceptable nuclear criticality safety margins. The spent-fuel carrying capacities of previous-generation transport casks have been limited primarily by requirements to remove heat and/or to provide shielding. Shielding and heat transfer requirements for casks designed to transport older spent fuel with longer decay times are reduced significantly. Thus a considerable weight margin is available to the designer for increasing the payload capacity. One method to achieve an increase in capacity is to reduce fuel assembly spacing. The amount of reduction in assembly spacing is limited by criticality and fuel support structural concerns. The optimum fuel assembly spacing provides the maximum cask loading within a basket that has adequate criticality control and sufficient structural integrity for regulatory accident scenarios. The incorporation of burnup credit in cask designs could result in considerable benefits in the transport of spent fuel. The acceptance of burnup credit for the design of transport casks depends on the resolution of system safety issues and the uncertainties that affect the determination of criticality safety margins. The remainder of this report will examine these issues and the integrated approach under way to resolve them. 20 refs., 2 figs.
Dip coating is the primary means of depositing sol-gel films for precision optical coatings. Sols are typically multicomponent systems consisting of an inorganic phase dispersed in a solvent mixture, with each component differing in volatility and surface tension. This, together with slow coating speeds (<1cm/s), makes analysis of the coating process complicated; unlike most high-speed coating methods, solvent evaporation, evolving rheology, and surface tension gradients alter significantly the fluid mechanics of the deposition stage. We set out to understand these phenomena with computer-aided predictions of the flow and species transport fields. The underlying theory involves mass, momentum, and species transport on a domain of unknown shape, with models and constitutive equations for vapor-liquid equilibria and surface tension. Due accounting is made for the unknown position of the free surface, which locates according to the capillary hydrodynamic forces and solvent loss by evaporation. Predictions of the effects of mass transfer, hydrodynamics, and surface tension gradients on final film thickness are compared with ellipsometry measurements of film thickness on a laboratory pilot coater. Although quantitative agreement is still lacking, both experiment and theory reveal that the film profile near the drying line takes on a parabolic shape. 2 refs., 2 figs.
Sandia National Laboratories is a multiprogram engineering laboratory that serves the nation through the Department of Energy (DOE), both in its programs and those of other agencies. Major research and development responsibilities cover nuclear weapons, arms control, energy, environment and other areas of strategic importance to national security. The principal mission is to support national defense policies by ensuring that the nuclear weapon stockpile meets the highest standards of safety, security, control and military performance. In May of 1968, the Albuquerque Office of DOE (then AEC) assigned the Quality Assurance function to Sandia Laboratories on all products for which Sandia has design responsibility. The Sandia Quality Improvement Plan presents a Quality Management System that integrates the Sandia quality policies and several independent improvement processes into a cohesive structure. This structure guides day-to-day operations toward strategic objectives. The Sandia Quality Policy provides the underlying principles for the management of our research and engineering efforts and establishes our customers as the central focus of our Sandia quality improvement efforts. Operationally, these efforts are centered around quality improvement processes based on good management practices developed by AT T, and progress is measured against the Malcolm Baldridge National Quality Award criteria. Developing a comprehensive plan based on these processes requires that we determine where we are, where we want to be, and how we measure our progress. 1 fig. (JF)
A review of the objectives and accomplishments of the Computational Benchmark Problem Committee (CBPC) of the American Nuclear Society Mathematics and Computation Division is presented. A list of the benchmark problems compiled by the CBPC and published by the Argonne Code Center is included, along with a list of the problems currently under review. A brief discussion of the challenge of benchmarking in the current environment of rapidly evolving computing technology is given. 20 refs., 3 tabs.
The Distant Light Program sponsored by the Defense Nuclear Agency (RAEE) is directed toward understanding the response of electronic systems to Source Region EMP (SREMP) and will result in the development of proven system hardening and validation techniques for SREMP. This program relies very strongly on testing in above ground test (AGT) simulators such as the HERMES III gamma ray simulator at Sandia National Laboratories in Albuquerque, New Mexico. This paper describes theoretical and experimental efforts aimed at understanding the gamma ray flux produced by HERMES III in terms of its time dependence, spatial variation and spectrum. As part of this characterization, the calibration of various measuring devices must be considered. This paper describes the progress made in characterizing the HERMES III radiation output through December of 1990.
Promoted iron catalysts are commonly used for Fischer-Tropsch (F-T) synthesis. Copper, potassium and silica are frequently employed as promoter species, either singly or in combination. The number of different iron catalyst formulations which have been investigated for F-T synthesis is enormous and there does not yet appear to be a general consensus as to the optimum catalyst composition. In addition, questions regarding the effects of variations in catalyst activation and reaction conditions are still open. Because of the large number of parameters involved in the development of F-T catalysts, a great deal of work remains to be done before the factors affecting catalyst performance are fully understood. In this paper one of these factors, namely the effects of variations in activation procedure on the surface composition of iron based F-T catalysts, will be investigated. Two different catalysts were studied. The first catalyst, with a composition of 100 Fe/5 Cu/4.2 K/25 SiO{sub 2} (parts by weight) whose little variation in activity procedure (1). The second catalyst (100 Fe/3 Cu/0.2 K) displays wide variations in activity with activation procedure (2). Surface compositions of these two catalysts were measured, after the activation treatments described above, using Auger electron spectroscopy (AES). It will be shown that the variations in catalyst activity observed by Bukur, et al. (1,2), correlate well with variations in surface composition, offering insights into the optimum conditions for catalyst activation. 9 refs., 6 figs.
An analysis is made of the experimental results of a minimum-time trajectory control scheme for a two-link flexible robot. An offline optimization routine determines a minimum-time, straight-line tip trajectory which stays within the torque constraints of the motors and ends with no vibrational transients. An efficient finite-element model is used in the optimization to approximate the flexible arm dynamics. The control strategy described is used to determine the feedback gains for the position, velocity, and strain gage signals from a quadratic cost criterion based on the finite-element model linearized about the straight-line tip trajectory. These feedback signals are added to the modeled torque values obtained from the optimization routine and used to control the robot arm actuators. The results indicate that this combination of model-based and error-driven control strategies achieves a closer tracking of the desired trajectory and a better handling of modeling errors than either strategy alone.
Lithium batteries have been used in a variety of applications for a number of years. As their use continues to grow, particularly in the consumer market, a greater emphasis needs to be placed on safety and reliability. There is a useful technique which can help to design cells and batteries having a greater degree of safety and higher reliability. This technique, known as fault tree analysis, can also be useful in determining the cause of unsafe behavior and poor reliability in existing designs.
During 1990, Sandia National Laboratories initiated an advanced lead-acid battery development program supported by the US Department of Energy's Office of Energy Management. The goal is to develop a low maintenance, cost effective battery by the mid- to late 1990's that is tailored to a variety of electric utility applications. Several parallel activities are being pursued to achieve this goal. One activity seeks to quantify the economic benefits of battery storage for specific cases in candidate utility systems and identify opportunities for field demonstration of battery systems at electric utility and utility customer sites. Such demonstrations will not only generate valuable operating experience data, but will also help in building user confidence in battery storage systems. Other activities concentrate on cell- and battery-level research and development aimed at overcoming shortcomings in existing technologies, such as Valve-Regulated Lead-Acid (VRLA), or, sealed lead-acid batteries.
A panel research experiment (PRE) was designed, built, and tested as a scaled-down model of a direct absorption receiver (DAR). The PRE is a 3-MWt DAR experiment that will allow flow testing with molten nitrate salt and provide a test bed for DAR testing with actual solar heating. In a solar central receiver system DAR, the heat absorbing fluid (a blackened molten nitrate salt) flows in a thin film down a vertical panel (rather than through tubes as in conventional receiver designs) and absorbs the concentrated solar flux directly. The ability of the flowing salt film to absorb the incident solar flux depends on the panel design, hydraulic and thermal fluid flow characteristics, and fluid blackener properties. Testing of the PRE is being conducted to demonstrate the engineering feasibility of the DAR concept. The DAR concept is being investigated because it offers numerous potential performance and economic advantages for production of electricity when compared to other solar receiver designs. The PRE utilized a 1-m wide by 6-m long absorber panel. The salt flow tests are being used to investigate component performance, panel deformations, and fluid stability. Salt flow testing has demonstrated that all the DAR components work as designed and that there are fluid stability issues that need to be addressed. Future solar testing will include steady-state and transient experiments, thermal loss measurements, responses to severe flux and temperature gradients and determination of peak flux capability, and optimized operation. In this paper, we describe the design, construction, and some preliminary flow test results of the Panel Research Experiment.
This study was undertaken in order to document and analyze the unique set of data on subsurface fracture characteristics, especially spacing, provided by the US Department of Energy's Slant Hole Completion Test well (SHCT-1) in the Piceance Basin, Colorado. Two hundred thirty-six (236) ft (71.9 m) of slant core and 115 ft (35.1 m) of horizontal core show irregular, but remarkably close, spacings for 72 natural fractures cored in sandstone reservoirs of the Mesaverde Group. Over 4200 ft (1280 m) of vertical core (containing 275 fractures) from the vertical Multiwell Experiment wells at the same location provide valuable information on fracture orientation, termination, and height, but only data from the SHCT-1 core allow calculations of relative fracture spacing. Within the 162-ft (49-m) thick zone of overlapping core from the vertical and deviated wellbores, only one fracture is present in vertical core whereas 52 fractures occur in the equivalent SHCT-1 core. The irregular distribution of regional-type fractures in these heterogeneous reservoirs suggests that measurements of average fracture spacing'' are of questionable value as direct input parameters into reservoir engineering models. Rather, deviated core provides data on the relative degree of fracturing, and confirms that cross fractures can be rare in the subsurface. 13 refs., 11 figs.
Current computer network protocols are very robust and capable of being used in a variety of different environments. Typically, the implementations of these protocols come to the user with preset parameters that provide reasonable performance for low delay- bandwidth product environments with low error rates, but these defaults do not necessarily provide optimal performance for high delay-bandwidth, high error rate environments. To provide optimal performance from the user's perspective, which is application to application, all equivalent layers of the protocol must be tuned. The key to tuning protocols is reducing idle time on the links caused by various protocol layers waiting for acknowledgments. The circuit bandwidth, propagation delay, error rate, number of outstanding packets, buffer length, number of buffers, and buffer size can all affect the observed idle time. Experiments have been conducted on test bed systems, and on live satellite and terrestrial circuits. Observations from these experiments led the authors to draw conclusions about the locations of common bottlenecks. Various aspects of network tuning and certain specific issues relating to the tuning of three protocols (DECnet, TCP/IP, NETEX) over various media types (point-to-point and broadcast) under several different conditions (terrestrial and satellite) are examined in this paper. Also described are the lessons learned about protocol and network tuning. 3 refs., 2 tabs.
A comparison of the short-transverse SCC behavior of 2090 in pH 5.5 Cl{sup {minus}} and alkaline CO{sub 3}{sup 2 {minus}}/Cl{sup {minus}} solutions using a static load smooth bar SCC technique was made. In the alkaline CO{sub 3}{sup 2 {minus}}/Cl{sup {minus}} solutions, E{sub br} for the {alpha}-Al matrix phase was 0.130 V more positive than the E{sub br} of the subgrain boundary T{sub 1} phase. In this environment, stress corrosion cracking test specimens subjected to potentials in the window defined by the two breakaway potentials failed along an intersubgranular path in less than an hour. In the Cl{sup {minus}} environment, the E{sub br} values for the two phases were nearly equal and this rapid SCC condition could not be satisfied; accordingly SCC failures were not observed. Rapid SCC failure of 2090 in CO{sub 3}{sup 2 {minus}}/Cl{sup {minus}} in our static load, constant immersion experiments appear to be related to recently reported pre-exposure embrittlement'' failures induced by immersing stressed specimens removed into ambient laboratory air after immersion in aerated NaCl solution for 7 days. In those experiments, specimens failed in less than 24 hours after removal from solution. Our polarization experiments have shown that the corrosion behavior of T{sub 1}, CO{sub 3}{sup 2 {minus}}/Cl{sup {minus}} environments, but the {alpha}-Al phase crack walls, is rapidly passivated. X-ray diffraction of the films which formed in simulated crevices suggests that this passivating film belongs to a class of compounds known as hydrotalcites.
Vertical axis wind turbine (VAWT) technology in the United States started in the early 1970s directly from the original work in Canada. The close, and very productive relationships among laboratories, universities and industry have continued since that time. This paper briefly discusses the significant technical progress and rather dramatic programmatic changes that have occurred in the past 18 to 24 months on the US side of the border. 20 refs., 14 figs.
Numerous small-scale in situ seal experiments have been emplaced in boreholes up to 38 in. in diameter at the WIPP. Seal materials include expansive salt concrete, bentonite, and crushed salt. Emplacement techniques stressed conventional technology and the use of available site personnel. Preliminary evaluation of the performance of these seals has been completed by using structural data from embedded instrumentation and fluid flow data from gas and brine flow measurements. Preliminary results suggest that submicrodarcy permeabilities can be obtained using these materials and that structural performance is satisfactory. 17 refs., 3 figs., 1 tab.
This paper describes a formal process for selecting, from a diverse set of proposed waste minimization activities, those activities that provide the greatest benefit to DOE. A methodology for evaluating and prioritizing proposals was developed to illustrate how the selection process works and what types of data are required to characterize waste minimization activities. It is clearly impossible to remove all aspects of subjective judgment from the proposal selection process. With this important consideration in mind, the methodology presented is put forth to enhance, not replace, the traditional DOE decision-making process. With relatively minor refinements, this methodology can be immediately useful to DOE Environmental Restoration and Waste Management and Defense Program organizations in preparing, evaluating, and prioritizing waste minimization proposals. 7 refs., 1 tab., 2 figs.
Our primary purpose in this test is to provide a brief general description of a few applications of various electrophoretic systems which have been investigated and have found use in various coating applications at Sandia National Laboratories. Both organic and inorganic suspensions in aqueous and non-aqueous media have been considered in these studies. Applications include high voltage insulating dielectrics, thermally conductive/electrically insulating films, adherent lubricating films, uniform photoresist films, glass coatings, and fissile uranium oxide/carbon composite films for studies of nuclear powered lasers. More recently, we have become interested in the beneficial environmental aspects of being able to provide protective polymer coatings which reduce or minimize the use of organic solvents required by traditional spray coat processes. Important practical factors which relate to film uniformity, adhesion, and composition are related to unique coating or plating capabilities and applications. 6 refs., 2 figs., 1 tab.
System dynamicists frequently encounter signals they interpret as realizations of normal random processes. To simulate these analytically and in the laboratory they use methods that yield approximately normal random signals. The traditional digital methods for generating such signals have been developed during the past 25 years. During the same period of time much development has been done in the theory of chaotic processes. The conditions under which chaos occurs have been studied, and several measures of the nature of chaotic processes have been developed. Some of the measures used to characterize the nature of dynamic system motions are common to the study of both random vibrations and chaotic processes. This paper considers chaotic processes and random vibrations. It shows contrasts between the two and situations where they are indistinguishable. The applicability of the Central Limit Theorem to chaotic processes is demonstrated. 12 refs., 8 figs.
A knowledge of the short term creep rupture behavior of Tantalum alloy T-111 is necessary to predict device integrity in the heat source section of Radioisotope Thermoelectric Generators (RTG's) at the end of service life, in the event of a fuel fire. High pressures exist in RTG's near the end of service life, these are caused by gas generation resulting from radioactive decay of the nuclear fuel. The internal pressure exerts a significant hoop stress on the T-111 alloy structural containment member. This paper analyses the short term creep behavior (rupture times up to {approximately}2 {times} 10{sup 3} hrs.) of cold worked (CW) T-111 alloy, using the existing data of Stephenson (1967). Corellations for the time to rupture, time to 1% strain and minimum creep rate have been obtained from this data using multivariable linear regression analysis. These results are compared to other short term rupture data for T-111 alloy. Finally, at the stress/temperature levels relevant to the RTG fuel fire scenario near the end of service life, the rupture time correlation for T-111 alloy predicts a rupture time of approximately 100 hrs. 10 refs., 3 figs., 1 tab.
Before the Waste Isolation Pilot Plant (WIPP) may begin service as the United States' first repository for the permanent disposal of transuranic (TRU) radioactive waste, the Department of Energy (DOE) must establish compliance with applicable environmental and safety regulations. This paper addresses one major regulation, the United States Environmental Protection Agency's (EPA) Environmental Radiation Protection Standards for Management and Disposal of Spent Nuclear Fuel, High-Level and Transuranic Radioactive Wastes, hereafter referred to as the Standard. The paper does not address compliance with other regulations. This paper summarizes Sandia National Laboratories' (SNL) early-1990 understanding of the WIPP Project's ability to comply with the long-term performance requirements set by Subpart B of the Standard, the Environmental Standards for Disposal. It also reviews the current understanding of questions critically affecting compliance and outlines the options available to assure that radionuclide releases will remain within regulatory limits. 10 refs., 3 figs.
A computational fluids dynamics scheme is presented to solve the unsteady Thin-Layer Navier-Stokes (TLNS) equations over a blunt body at high altitude, high Mach number atmospheric reentry flow conditions. This continuum approach is directed to low density hypersonic flows by accounting for non-zero bulk viscosity effects in near frozen flow conditions. The TLNS equations are solved over an axisymmetric body at zero incidence relative to the free stream. The time dependent axisymmetric governing equations are transformed into a computational plane, then cast into weak conservative form and solved using a first-order fully implicit scheme in time with second-order flux vector splitting for spatial derivatives. The physical domain is defined over representative sphere and sphere/cone geometries using a body-fitted clustered algebraic grid within a fixed domain (i.e., shock capturing). At the present time, nonequilibrium thermo-chemistry effects are not modeled. Catalytic wall, ionization and radiation effects are also excluded from the current analysis. However, the significant difference from previous studies is the inclusion of the capability to model non-zero bulk viscosity effects. The importance of bulk viscosity is reviewed and blunt body flow field solutions are presented to illustrate the potential contribution of this phenomena at high altitude hypersonic conditions. The current technique is compared with experimental data and other approximate continuum solutions. A variety of test cases are also presented for a wide range of free stream Mach conditions. 18 refs., 42 figs.
An obvious group of applications for HTS materials is microwave and millimeter wave circuitry. Besides low loss, the unique features of these materials, such as flux flow, can be exploited. We have been concentrating on the Tl-Ca-Ba-Cu-O family of materials. The film growth techniques, lithographic processing methods and the characteristics of several devices we have developed will be presented. These devices include a flux flow-based transistor with demonstrated operation at over 35 GHz, real gain in a 50 ω system and potentially useful non-linearities and impedance levels. A number of passive microwave components are under investigation to form a more complete HTS microwave technology group.
An advanced Synthetic Aperture Radar Motion Compensation System has been developed by Sandia National Laboratories (SNL). The system includes a miniaturized high accuracy ring laser gyro inertial measurement unit, a three axis gimbal pointing and stabilization assembly, a differential Global Positioning System (GPS) navigation aiding system, and a pilot guidance system. The system provides several improvements over previous SNL motion compensation systems and is capable of antenna stabilization to less than 0.01 degrees RMS and absolute position measurement to less than 5.0 meters RMS. These accuracies have been demonstrated in recent flight testing aboard a DHC-6-300 Twin Otter'' aircraft.
As part of the Yucca Mountain Project, our research program to develop and validate conceptual models for flow and transport through unsaturated fractured rock integrates fundamental physical experimentation with conceptual model formulation and mathematical modeling. Our research is directed toward developing and validating macroscopic, continuum-based models and supporting effective property models because of their widespread utility within the context of this project. Success relative to the development and validation of effective property models is predicted on a firm understanding of the basic physics governing flow through fractured media, specifically in the areas of unsaturated flow and transport in a single fracture and fracture-matrix interaction.
Construction of well-posed scenarios for the range of conditions possible at any proposed repository site is a critical first step to assessing total system performance. Event tree construction is the method that is being used to develop potential failure scenarios for the proposed nuclear waste repository at Yucca Mountain. An event tree begins with an initial event or condition. Subsequent events are listed in a sequence, leading eventually to release of radionuclides to the accessible environment. Ensuring the validity of the scenarios requires iteration between problems constructed using scenarios contained in the event tree sequence, experimental results, and numerical analyses. Details not adequately captured within the tree initially may become more apparent as a result of analyses. To illustrate this process, we discuss the iterations used to develop numerical analyses for PACE-90 using basaltic igneous activity and human-intrusion event trees.
Yucca Mountain, located in southwestern Nevada, is the site for a proposed high-level nuclear waste repository. The hydrologic units at Yucca Mountain appear to have quite different material characteristics. Additionally, measurements show that the material properties within each hydrologic unit vary significantly. Rock core samples taken from this site indicate that the volcanic tuff is highly fractured and nonhomogeneous. Modeling studies were conducted to determine the effects of material heterogeneities on the flow of water through rock. Multiple numerical calculations were made using random variations in spatial distributions of material properties. The results of these material variations on flow resistance, mechanical dispersion, and channeling were determined. Computed results were compared with a linear analytical model. Good agreement was obtained in the majority of the flow cases investigated.
Under the sponsorship of the US Nuclear Regulatory Commission (NRC), Sandia National Laboratories (SNL) is developing a performance assessment methodology for the analysis of long-term disposal and isolation of high-level nuclear wastes (HLW) in alternative geologic media. As part of this exercise, SNL created a conceptualization of ground-water flow and radionuclide transport in the far field of a hypothetical HLW repository site located in unsaturated, fractured tuff formations. This study provides a foundation for the development of conceptual mathematical, and numerical models to be used in this performance assessment methodology. This conceptualization is site specific in terms of geometry, the regional ground-water flow system, stratigraphy, and structure in that these are based on information from Yucca Mountain located on the Nevada Test Site. However, in terms of processes in unsaturated, fractured, porous media, the model is generic. This report also provides a review and evaluation of previously proposed conceptual models of unsaturated and saturated flow and solute transport. This report provides a qualitative description of a hypothetical HLW repository site in fractured tuff. However, evaluation of the current knowledge of flow and transport at Yucca Mountain does not yield a single conceptual model. Instead, multiple conceptual models are possible given the existing information.
Three series of measurements were performed on oriented cores of several Yucca Mountain tuffs to determine the importance of mechanical anisotropy in the intact rock. Outcrop and drillhole samples were tested for acoustic velocities, linear compressibilities, and strengths in different orientations. The present data sets are preliminary, but suggest the tuffs are transversely anisotropic for these mechanical properties. The planar fabric that produces the anisotropy is believed to be predominantly the result of the preferred orientation of shards and pumice fragments. The potential of significant anisotropy has direct relevance to the formulation of constitutive formulation and the analyses of an underground opening within Yucca Mountain.
Sandia National Laboratories, as a participant in the Yucca Mountain Project, administered by the Nevada Operations Office of the US Department of Energy, is in the process of evaluating a proposed site for geologic disposal of high-level nuclear wastes in the volcanic tuffs at Yucca Mountain, Nevada. In a repository, loads will be imposed on the rock mass as a result of excavation of the openings and heating of the rock by the nuclear waste. In an attempt to gain a better understanding of the thermal, mechanical, and thermomechanical response of fractured tuff, a series of experiments have been performed, and measurements have been taken in the welded and nonwelded tuffs at the G-Tunnel underground test facility at Rainier Mesa, Nevada. Comparisons between measured and calculated data of the G-Tunnel High-Pressure Flatjack Development Experiment are presented in this investigation. Calculated results were obtained from two dimensional finite element analysis using a recently developed compliant-joint rock-mass model. The purpose of this work was to assess the predictive capability of the model based on limited material property data for the G-Tunnel welded tuff. The results of this evaluation are discussed.
We report the first experiments evaluating the beam generation by the new 4-MV RLA injector. Beams of 15 to 27 kA current were produced and successfully transported up to the first post-accelerating cavity (ET-2), 1.3 m downstream. The beam radius was measured with an x-ray pin-hole camera and found to be equal to 5 mm. We selected an apertured ion-focused foilless diode among the various available diode options. It is the simplest and easiest to operate and can be adjusted to provide variable beam impedance loads. Experimental results will be presented and compared with numerical simulations.
Two controllers are developed to provide attitude control of a spinning rocket that has a thrust vectoring capability. The first controller has a single-input/single-output design that ignores the gyroscopic coupling between the control channels. The second controller has a multi-input/multi-output structure that is specifically intended to account for the gyroscopic coupling effects. A performance comparison between the two approached is conducted for a range of roll rates. Each controller is tested for the ability to track step commands, and for the amount of coupling impurity. Both controllers are developed via a linear-quadratic-regulator synthesis procedure, which is motivated by the multi-input/multi-output nature of second controller. Time responses and a singular value analysis are used to evaluate controller performance. This paper describes the development and comparison of two controllers that are designed to provide attitude control of a spinning rocket that is equipped with thrust vector control. 12 refs., 13 figs., 2 tabs.
The theoretical basis for the relationship between moisture content and light transmission (FFM) is developed, and shown to correspond well to the observed behavior. A calibration procedure for FFM based on the relationship between moisture content and matric potential is presented and tested. Means of expanding the range of sensitivity of the FFM are discussed.
Vawter, G.A.; Myers, D.R.; Brennan, T.M.; Hammons, B.E.
We report dramatic improvements to the implanted-planar buried-heterostructure graded-index separate confinement heterostructure (IPBH-GRINSCH) laser in (AlGa)As/GaAs which produces low threshold current, continuous-wave operation. Our process features significantly reduced fabrication complexity of high quality, index-guided laser diodes compared to regrowth techniques and, in contrast to diffusion-induced disordering, allows creation of self-aligned, buried, blocking junctions by ion implantation. The improved single-stripe IPBH-GRINSCH lasers exhibit 39 mA threshold current, cw operation.
Shock and unloading experiments on quartz and silicate rocks indicate that the release adiabats lie below the Hugoniot. The hysteresis and energy dissipation inherent in this situation have important wave propagation implications. On loading, there is a pressure-induced transition to the stishovite phase which does not occur under conditions of thermodynamic equilibrium, in that the Hugoniot passes through a metastable mixed-phase region for several tens of GPa. One interpretation of the unloading data is that the transition is not reversible, and the phase mixture remains frozen on unloading. However, material strength may also play a role. A complete thermodynamically consistent equation of state which includes phase transitions and strength effects has been developed and used to examine shock and release data on quartz and silicate rocks in order to quantify the kinetics of the reverse transition and to separate the hysteretic effects due to reverse phase transition kinetics from those due to material strength. The model allows quantitative determination of the effect of reverse transition kinetics on ground shock propagation in silicate materials.
On-line chemical monitoring systems can help ensure safe, environmentally sound operation of industrial processes using hazardous chemicals. Using polymer-coated surface acoustic wave (SAW) sensors, we have demonstrated monitors that are capable of detecting dilute concentrations of volatile organic species. Using changes in both wave velocity and wave attenuation, the identity and concentration of an isolated chemical species can be determined. A polysiloxane coating has been found to provide unique properties for monitoring chlorinated hydrocarbons (CHCs) such as trichloroethylene: good discrimination of CHCs from most other organic species, rapid and reversible sensor response, and low detection limits. Using this technology, a portable acoustic wave sensor (PAWS) system has been constructed.
Quantitative analysis routines based on the Bence-Albee, the ZAF, and the {Phi}({rho}Z) techniques are available for the TASK8 microprobe operating system. All of the routines are able to be run from within TASK8 or as stand alone programs. For quick analyses, energy dispersive x-ray data can be collected and processed by running the Tracor standardless quantitative (SQ) routine from within TASK8. For normal analyses, data are collected via the wavelength spectrometers. The procedures and routines described in this document permit the interactive collection and processing of data via joystick control or the automatic collection and processing of data from up to seven line traces or an essentially unlimited number of preselected points. 7 refs., 5 figs., 1 tab.
Sandia National Laboratories operates the Primary Standards Laboratory (PSL) for the Department of Energy, Albuquerque Operations Office (DOE/AL). This report summarizes metrology activities that received emphasis in the first half of 1990 and provides information pertinent to the operation of the DOE/AL system-wide Standards and Calibration Program.
Sandia National Laboratories, Albuquerque, has been designated as Lead Center for the Exploratory Battery Technology Development and Testing Project, which is sponsored by the US Department of Energy's Office of Energy Storage and Distribution. In this capacity, Sandia is responsible for the engineering development of advanced rechargeable batteries for both mobile and stationary energy storage applications. This report details the technical achievements realized in pursuit of the Lead Center's goals during calendar year 1989. 4 refs., 84 figs., 18 tabs.
This report describes some field tests of the CUBIC CR-100 distance measuring equipment. The distance measurements depend on the refractivity of the atmospheric. The CR-100 uses 320 for the refractivity. For the Albuquerque area on a clear spring day, 220 is a more realistic value for refractivity. This difference of 100 between the actual and assumed refractivities causes the range error to accumulate at the rate of 1 meter per 10,000 meters of range. For example, a difference of 100 in refractivity forces the measured range to contain an error of 5 meters for a 50,000 meter baseline. 12 figs.
The Explosive Components Facility (ECF) is to be a new major facility in the Sandia National Laboratories (SNL) Weapons Program. The ECF is a self-contained, secure site on SNL property and is surrounded by Kirtland Air Force Base which is located 6-1/2 miles east of downtown Albuquerque, New Mexico. The ECF will be dedicated to research, development, and testing of detonators, neutron generators, batteries, explosives, and other weapon components. It will have capabilities for conducting explosive test fires, gas gun testing, physical analyses, chemical analyses, electrical testing and ancillary explosive storage in magazines. The ECF complex is composed of a building covering an area of approximately 91,000 square feet, six exterior explosive service magazines and a remote test cell. Approximately 50% of the building space will be devoted to highly specialized laboratory and test areas, the other 50% of the building is considered nonhazardous. Critical to the laboratory and test areas are the blast-structural design consideration and operational considerations, particularly those concerning personnel access control, safety and environmental protection. This area will be decoupled from the rest of the building to the extent that routine tests will not be heard or felt in the administrative area of the building. While the ECF is designed in accordance with the DOE Explosives Safety Manual to mitigate any off-site blast effects, potential injuries or death to the ECF staff may result from an accidental detonation of explosive material within the facility. Therefore, reducing the risk of exposing operation personnel to hazardous and energetic material is paramount in the design of the ECF.
This report describes the Phase 1 drilling operations for the Magma Energy Exploratory Well near Mammoth Lakes, California. An important part of the Department of Energy's Magma Energy Program, this well is designed to reach an ultimate depth of 20,000 feet or a bottomhole temperature of 500{degree}C, whichever comes first. There will be four drilling phases, at least a year apart, with scientific investigations in the borehole between the drilling intervals. Phase 1 of this project resulted in a 20 inch cased hole to 2558 feet, with 185 feet of coring beyond that. This document comprises a narrative of the daily activities, copies of the daily mud and lithologic reports, time breakdowns of rig activities, inventories of lost circulation materials, temperature logs of the cored hole, and a strip chart mud log. 2 figs.
The validity of scale model impact evaluation of the SST Transportation System is acceptable based on Dimensional Analysis (Buckingham Pi Theorem) and the work of numerous programs that have evaluated the agreement among dimensional analysis, several different reduced-size models and full-scale impact test data. Excellent accuracy has been demonstrated between scale models and full-scale impact data when collected in conformance with the Buckingham Pi Theorem. 20 refs., 4 figs.
A five-step procedure was used in the 1990 performance simulations to construct probability distributions of the uncertain variables appearing in the mathematical models used to simulate the Waste Isolation Pilot Plant's (WIPP's) performance. This procedure provides a consistent approach to the construction of probability distributions in cases where empirical data concerning a variable are sparse or absent and minimizes the amount of spurious information that is often introduced into a distribution by assumptions of nonspecialist. The procedure gives first priority to the professional judgment of subject-matter experts and emphasizes the use of site-specific empirical data for the construction of the probability distributions when such data are available. In the absence of sufficient empirical data, the procedure employs the Maximum Entropy Formalism and the subject-matter experts' subjective estimates of the parameters of the distribution to construct a distribution that can be used in a performance simulation. 23 refs., 4 figs., 1 tab.
This report documents the data available as of August 1990 and used by the Performance Assessment Division of Sandia National Laboratories in its December 1990 preliminary performance assessment of the Waste Isolation Pilot Plant (WIPP). Parameter values are presented in table form for the geologic subsystem, engineered barriers, borehole flow properties, climate variability, and intrusion characteristics. Sources for the data and a brief discussion of each parameter are provided. 101 refs., 72 figs., 21 tabs.
A theoretical model was developed for the minimum charge to trigger a gaseous detonation in spherical geometry as a generalization of the Zeldovich model. Careful comparisons were made between the theoretical predictions and experimental data on the minimum charge to trigger detonations in propane-air mixtures. The predictions are an order of magnitude too high, and there is no apparent resolution to the discrepancy. A dynamic model, which takes into account the experimentally observed oscillations in the detonation zone, may be necessary for reliable predictions. 27 refs., 9 figs.