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)