Numerous investigations have studied the potential for chaotic vibrations of nonlinear systems. It has been shown for many simple nonlinear systems, that when they are excited severely enough, or with the appropriate parametric combinations, that they will execute chaotic vibrations. The present investigation considers the potential for the occurrence of chaos in a practical nonlinear system -- the isolated accelerometer. A simple, first order model is proposed for the isolated accelerometer, and it is shown that chaos can occur in the isolated accelerometer. A preliminary investigation into the bearing that this chaos potential has on the measurement of shock response is summarized. 7 refs.
Carrier-driven photochemical reactions require direct participation of free carriers for the chemical reaction to proceed. Therefore, they can be selectively suppressed by increasing the carrier recombination rate through creation of defects using ion implantation. The residual defect concentration following ion implantation should correlate with etching suppression. Changes in the Raman LO-phonon lineshape correlate well with the degree of etching suppression and predict etching behavior better than defect concentrations calculated with the Monte Carlo code, TRIM. Raman spectroscopy may be a useful pre-etch diagnostic to predict the degree of etching suppression resulting from a given implantation treatment. 11 refs.
Direct containment heating (DCH) has recently been studied at Sandia National Laboratory`s Surtsey facility in a number of experiments in which high-temperature thermite melts are ejected by pressurized steam from a melt generator into scaled reactor cavities. Steam blowdown from the melt generator disperses at least part of the melt into the Surtsey vessel. Efficient team-metal chemical reaction was observed in many of the experiments. Analysis of the results suggests that hydrogen generation occurs primarily in the cavity can actually reduce hydrogen generation by separating the debris from the blowdown steam. Debris-gas heat transfer appears to include both a component that takes place in the cavity in proportion to the hydrogen generation, and a second component that takes place in the Surtsey vessel itself. The magnitude of the latter depends upon the amount of debris dispersed and the length of the unobstructed flight path in the Surtsey vessel. Some possible implications of these results are discussed.
A Senate Committee requested assistance from Sandia in determining the adequacy of the investigation of the incident aboard the USS IOWA. This currently unexplained explosion occurred in Turret 2 of the battleship on April 19, 1989, killing 47 crewmen. The investigation included material characterization of debris found after the explosion, ignition experiments to characterize the propellant, and analytic modeling of the mechanics, interior ballistics and ignition. The analytic modeling is described in this paper. The modeling of the incident was concerned with the mechanics of the ramming equipment used to load the 16 inch guns, and the interior ballistic and ignition of the propellant. Many separate analyses were performed to explain the crushing of the propellant grains, the dynamics and location of ignition of the propellant train, and the presence of damage after the incident. The goal of this modeling was to assess the feasibility of the various events in the turret, and to identify the cause of the incident. An item of particular interest was damage to the rammer control handle quadrant. The US Navy conjectured that the blast propelled the rammermans seat into the quadrant in such a way as to suggest low speed ram during the incident. The speed of the ram was discovered to be very important in determining the probability of ignition during an overram, and an analysis of the rammermans seat motion was completed. In order to understand how the seat impacts the quadrant, a three-dimensional finite element analysis was completed using ABAQUS/Explicit. The loading of the seat was due to two-phase gas and propellant flow through the bag train and into the turret volume. The results showed that impact onto the quadrant probably first occurred at the rear, dislodging it from its mount. This analysis was pivotal in the examination of the incident, and was the final evidence that the cause of the explosion could not be conclusively determined.
High spatial resolution x-ray microanalysis in the analytical electron microscope (AEM) describes a technique by which chemical composition can be determined on spatial scales of less than 50 nm. Dependent upon the size of the incident probe, the energy (voltage) of the beam, the average atomic number of the material being analyzed, and the thickness of the specimens at the point of analysis it is possible to measure uniquely the composition of a region 2--20 nm in diameter. Conventional thermionic (tungsten or LaB{sub 6}) AEMs can attain direct spatial resolutions as small as 20 nm, while field emission (FEG) AEM`s can attain direct spatial resolutions approaching 2 nm. Recently, efforts have been underway to extract compositional information on a finer spatial scale by using massively parallel Monte Carlo electron trajectory simulations coupled with AEM measurements. By deconvolving the measured concentration profile with the calculated x-ray generation profile it is possible to extract compositional information at near atomic resolution.
Chemical and physical transformations involved in ion implantation processes in glasses determine changes in mechanical. and tribological properties, in network dilatation, in induced optical absorption and luminescence and in the composition and chemical behavior as a function of different experimental conditions (ion, energy, dose, target temperature). Variations of chemical etch rate in HF are related to radiation damages and formation of compounds. A systematic study of the etch rate changes in silica due to Ar, N, Si plus N implants has been performed. Structure modifications at depths greater than the corresponding implanted ion ranges are evidenced for nuclear deposited energy greater than 10{sup 22} keV cm{sup {minus}3}. Formation of silicon oxynitrides reduces the etch rate values.
Archimedes is a prototype mechanical assembly system which generates and executes robot assembly programs from a CAD model input. The system seeks to increase flexibility in robotic mechanical assembly applications by automating the programming task. Input is a solid model of the finished assembly, augmented by additional design information such as weld specifications. Parts relationships and geometric constraints are deduced from the solid model. A rule-based planner generates a ``generic`` assembly plan that satisfies the geometric constraints, as well as other constraints embodied in the rules. A plan compiler then converts the generic plan into code specific to an application environment. Other outputs include fixture designs, workcell layout information, object-recognition (vision) routines, grasp plans, and executable code for controlling the robot and workcell accessories. Lessons from operating and demonstrating the system are presented, with a particular emphasis on the implications for future systems. 12 refs.
Isolated accelerometer measurement systems are used to measure environments composed of a wide spectrum of frequencies including the natural frequency of the isolated accelerometer. Because the isolated accelerometer measurement system is a nonlinear system, it is subject to the potential for chaotic vibrations. it is clear that this potential if realized, affects the response of the measurement system to vibration input and perhaps to shock input also. This paper explores the effects that the potential for chaotic vibrations and nonlinear response, in general, has on the random vibration response of the isolated accelerometer measurement system. Specifically, the system response to white noise is investigated and assessed in terms of response histogram and response spectral density. 6 refs.
In the Federal Register, Volume 51, Number 168, NRC has intended the use of IMPACTS-BRC to evaluate petitions for evaluating radioactive waste streams as below regulatory concern. IMPACTS-BRC is a generic radiological assessment code that allows calculation of potential impacts to maximum individuals, waste disposal workers, and the general population resulting from exemption of very low-level radioactive waste from regulatory control. The code allows calculations to be made of human exposure to the waste by many pathways and exposure scenarios. This document describes the code history and the quality assurance work that has been carried out on IMPACTS-BRC. The report includes a summary of all the literature reviews pertaining to IMPACTS-BRC up to Version 2.0. The new code and data verification work necessary to produce IMPACTS-BRC, Version 2.1 is presented. General comments about the models and treatment of uncertainty in IMPACTS-BRC are also given.
This work describes the collection, handling, transportation, thermal desorption, and analysis of explosive vapors using quartz collection tubes. A description of the sampling system is presented, along with the collection efficiency of the quartz tubes and some of the precautions necessary to maintain the sample integrity. The design and performance characteristics of the thermal desorption system are also discussed. Collection of explosive vapor using empty, 0.25 inch O.D. by 5.25 inch long quartz tubes at a flow rate of 200 mL min-1 is quite different. Thermal desorption of the explosive vapor molecules using a furnace that allows control of the gas phase chemistry in the IMS has been shown to provide a reliable, reproducible means of analysis. Empty quartz tubes provide a sharper desorption profile than packed collection tubes, resulting in a better signal-to-noise ratio, and perhaps, a lower detection limit than packed quartz tubes. Both the ion drift time of the explosive and its desorption characteristics can provide a means of identification. Sample handling, packaging, and transportation methods which minimize sample loss and contamination have been developed and evaluated.
This report contains the purchasing and materials management operating highlights for Fiscal Year 1991. Included in the report are compiled data on: personnel; type of procurement; small business procurements; disadvantaged business procurements; woman-owned business procurements; New Mexico commercial business procurements; Bay Area commercial business procurements; commitments by states and foreign countries to commercial suppliers; and, transportation activities. Other statistical data tables enumerate the following: the twenty-five commercial contractors receiving the largest dollar commitments; commercial contractors receiving commitments of $1000 or over; integrated contractor and federal agency commitments of $1000 or over from Sandia National Laboratories-Albuquerque and Livermore; and, transportation commitments of $1000 or over from Sandia National Laboratories-Albuquerque and Livermore.
This white paper addresses the issue of banning lead from solders used in electronics manufacturing. The current efforts by legislative bodies and regulatory agencies to curtail the use of lead in manufactured goods, including solders, are described. In response to a ban on lead or the imposition of a tax which makes lead uneconomical for use in solder alloys, alternative technologies including lead-free solders and conductive epoxies are presented. The recommendation is made that both users and producers of solder materials join together as partners in a consortium to address this issue in a timely and cost-effective manner.
The MELCOR code has been used to simulate the ST-1 and ST-2 in-pile product source term experiments performed in the ACRR facility. As expected, there were no major differences observed in the results calculated for the different test conditions. The CORSOR, CORSOR-M and CORSOR-Booth release models all were tested, and the effect of including the surface-volume correction term was evaluated. MELCOR results were compared to test data and to VICTORIA results, and also directly to the correlations and to ST-1/ST-2 results predicted by Battelle using their stand-alone CORSOR code to verify that the models have been implemented correctly in MELCOR. The release rates and total release fractions calculated by MELCOR generally agreed well with the test data, for both volatile and refractory species, with none of the release model options available yielding consistently better agreement with data for species. Sensitivity studies checking for time step and noding effects and machine dependencies were done, and some machine dependencies associated with very small numbers were identified and corrected in the code. Additional sensitivity studies were run on parameters affecting core heatup and core damage, including both variations in code models such as convective heat transfer coefficients, radiation view factors, candling assumptions, and in experimental conditions such as pressures, flow rates, power levels, and insulation thermal conductivity. Code and user input modeling errors encountered in these analyses are described.
This paper presents a method to solve partial differential equations governing two-phase fluid flow by using a genetic algorithm on the NCUBE/2 multiprocessor computer. Genetic algorithms represent a significant departure from traditional approaches of solving fluid flow problems. The inherent parallelism of genetic algorithms offers the prospect of obtaining solutions faster than ever possible. The paper discusses the two-phase flow equations, the genetic representation of the unknowns, the fitness function, the genetic operators, and the implementation of the genetic algorithm on the NCUBE/2 computer. The paper investigates the implementation efficiency using a pipe blowdown test and presents the effects of varying both the genetic parameters and the number of processors. The results show that genetic algorithms provide a major advancement in methods for solving two-phase flow problems. A desired goal of solving these equations for a specific simulation problem in real time or faster requires computers with an order of magnitude more processors or faster than the NCUBE/2`s 1024.
Although plasma cleaning is a recognized substitute for solvent cleaning in removing organic contaminants, current cleaning rates are impractically low for many applications. A set of experiments is described which demonstrate that the rate of plasma removal of organic contaminants can be greatly increased by modification of the plasma chemistry. A comparison of plasma cleaning rates of argon, oxygen and oxygen/sulfur hexafluoride gases shows that the fluorine containing plasma is at least an order of magnitude faster at etching organics. Rates are reported for the removal of polymer films and of A-9 Aluminum cutting fluid. 7 refs.
Measuring the yield of an underground nuclear detonation using sensor cables has been proposed for verification purposes. These cables not only sense the signals associated with the yield they also capture the sensitive primary and secondary electromagnetic pulses associated with the detonation but have nothing to do with the yield. An anti-intrusiveness device is to be connected to the sensor cable to prevent the electromagnetic pulses from passing through to the verifier. The anti-intrusiveness device both attenuates the electromagnetic pulses and adds noise to the cable over the interval of time that the electromagnetic pulses may be present. This report addresses the problem of determining the optimum noise spectral density for masking the electromagnetic pulses. To this end it derives an expression for the lower bound on the error in the estimation of the time separation between two pulses when the time of arrival of neither is known and they are imbedded in Gaussian noise. The noise spectral shapes considered are white, and lowpass, and bandpass.
UPEML is a machine-portable program that emulates a subset of the functions of the standard CDC Update. Machine-portability has been achieved by conforming to ANSI standards for Fortran-77. UPEML is compact and fairly efficient; however, it only allows a restricted syntax as compared with the CDC Update. This program was written primarily to facilitate the use of CDC-based scientific packages on alternate computer systems such as the VAX/VMS mainframes and UNIX workstations. UPEML has also been successfully used on the multiprocessor ELXSI, on CRAYs under both UNICOS and CTSS operating systems, and on Sun, HP, Stardent and IBM workstations. UPEML was originally released with the ITS electron/photon Monte Carlo transport package, which was developed on a CDC-7600 and makes extensive use of conditional file structure to combine several problem geometry and machine options into a single program file. UPEML 3.0 is an enhanced version of the original code and is being independently released for use at any installation or with any code package. Version 3.0 includes enhanced error checking, full ASCII character support, a program library audit capability, and a partial update option in which only selected or modified decks are written to the complete file. Version 3.0 also checks for overlapping corrections, allows processing of pested calls to common decks, and allows the use of alternate files in READ and ADDFILE commands. Finally, UPEML Version 3.0 allows the assignment of input and output files at runtime on the control line.
The Planning and Staff Support of the Sandia National Laboratories publishes a monthly bulletin titled, Energy and Environment. The bulletin facilitates technology exchange with industries, universities, and with other government agencies. This bulletin is for the month of April 1992 and covers such things as new methods of soldering which reduces environmental threats by avoiding chlorofluorocarbon solvents. Some technologies developed are soldering in controlled atmospheres, acid-vapor soldering, and laser soldering. Another topic in this bulletin is the designing of catalysts of chemical reactions by computers. Biomimetic catalysts are being created by Computer-Aided Molecular Design. These biomimetic catalysts can aid in fuel conversion. In-situ remediation of soils contaminated by heavy metals was another topic in this bulletin. This in-situ process is called, electrokinetic remediation. It uses electrodes to induce a metal-attracting electric field in the ground. The last topic in this bulletin is the design of a semiconductor bridge (SCB) which is used to improve the timing and effectiveness of blasting. Timing and accuracy is important; and the blasting industry is no exception. This SCB gives a low-energy pulse which causes a doped region on a polysilicon substrate into a bright plasma. This plasma discharge causes the ignition and produces an accurate explosion in microseconds. (MB)
Seventeen small-scale brine inflow experiment boreholes have been and are currently being monitored for brine accumulation. All of the boreholes were drilled from underground excavations at the Waste Isolation Pilot Plant (WIPP) near Carlsbad, NM. Experiments are ongoing in Room D, Room L4, and the Q access drift in the WIPP underground. The boreholes range from approximately 5 to 90 cm in diameter and from 3 to 6 m in length. The objective of these experiments is to provide data for use in the development and validation of a predictive, mechanistic model for brine inflow to the repository. There is considerable variability in the observed responses of the different boreholes, and there are also significant similarities. Two of the boreholes in Room D have yielded no brine in more than 3.5 years, while all 15 of the other boreholes have produced anywhere from 2 to 90 kg of brine. Inflow rates vary by as much as 2 orders of magnitude for boreholes of the same dimensions in the same general location; however, inflow rates measured in most of the boreholes are of the same order of magnitude. Decreasing, increasing, and steady inflow rates have been measured. Nevertheless, 9 of the 15 brine-producing boreholes behaved similarly early in their history. These 9 boreholes all exhibited a relatively high initial inflow rate followed by a fairly smooth decline with time. Variabilities in borehole response can be explained by assuming there are heterogeneities in the formation tested. In most cases these heterogeneities are believed to be excavation-induced. Data from these experiments suggest that flow near excavations has been altered by rock deformation, including fracturing. Additional experiments are required to differentiate between a far-field, near-field, or combination brine source and to characterize the significant flow mechanism or mechanisms.
A high-velocity impact testing technique, utilizing a tethered rocket, is being developed at Sandia National Laboratories. The technique involves tethering a rocket assembly to a pivot location and flying it in a semicircular trajectory to deliver the rocket and payload to an impact target location. Integral to developing this testing technique is the parallel development of accurate simulation models. An operational computer code, called ROAR (Rocket-on-a-Rope), has been developed to simulate the three-dimensional transient dynamic behavior of the tether and motor/payload assembly. This report presents a discussion of the parameters modeled, the governing set of equations, the through-time integration scheme, and the input required to set up a model. Also included is a sample problem and a comparison with experimental results.
The Plasma/Wall Interaction and High Heat Flux Materials and Components Task Groups typically hold a joint meeting each year to provide a forum for discussion of technical issues of current interest as well as an opportunity for program reviews by the Department of Energy (DOE). At the meeting in September 1990, reported here, research programs in support of the International Thermonuclear Experimental Reactor (ITER) were highlighted. The first part of the meeting was devoted to research and development (R&D) for ITER on plasma facing components plus introductory presentations on some current projects and design studies. The balance of the meeting was devoted to program reviews, which included presentations by most of the participants in the Small Business Innovative Research (SBIR) Programs with activities related to plasma wall interactions. The Task Groups on Plasma/Wall Interaction and on High Heat Flux Materials and Components were chartered as continuing working groups by the Division of Development and Technology in DOE`s Magnetic Fusion Program. This report is an addition to the series of ``blue cover`` reports on the Joint Meetings of the Plasma/Wall Interaction and High Heat Flux Materials and Components Task Groups. Among several preceding meetings were those in October 1989 and January 1988.
The switch delay time of the MC3858 sprytron was measured using a test matrix consisting of 36 different trigger circuit configurations. The test matrix allowed the measurement of switch delay times for peak trigger voltages ranging from 47 V to 1340 V and for stored trigger energies ranging from 0.023 mJ to 2.7 mJ. The average switch delay time was independent of peak trigger voltage above approximately 800 V. Similarly, the average switch delay was independent of trigger stored energy above approximately 0.5 mJ. Below these saturation values, the average switch delay increases rapidly with decreasing trigger voltage or esergy. In contrast to the average switch delay time, the shot-to-shot variability in switch delay time does not appear to be strongly affected by peak trigger voltage as long as the trigger voltage is groater than 100 V. Below 100 V, the variability in switch delay time rises rapidly due to failure of the trigger to undergo immediate high voltage breakdown when trigger voltage is applied. The effect of an abnormally-high-resistance trigger probe on switch delay time was also investigated. It was found that a high-resistance probe behaved as a second overvoltage gap in the trigger circuit. Operation with a peak trigger voltage greater than the breakdown voltage of this second gap yielded delay times comparable to operation with a normal trigger. Operation with a peak trigger voltage less than the breakdown voltage of this second gap increased the switch delay time by an amount comparable to the time required to ramp the trigger circuit output up to the breakdown voltage of the second gap. Finally, the effect that varying the bias voltage applied to the sprytron has on switch delay time was measured. The switch delay time did not appear to depend on bias voltage for bias voltages between 725 V and 2420 V.
Performance assessment modeling for High Level Waste (HLW) disposal incorporates three different types of uncertainty. These include data and parameter uncertainty, modeling uncertainty (which includes conceptual, mathematical, and numerical), and uncertainty associated with predicting the future state of the system. In this study, the potential impact of conceptual model uncertainty on the estimated performance of a hypothetical high-level radioactive waste disposal site in unsaturated, fractured tuff has been assessed for a given group of conceptual models. This was accomplished by taking a series of six, one-dimensional conceptual models, which differed only by the fundamental assumptions used to develop them, and conducting ground-water flow and radionuclide transport simulations. Complementary cumulative distribution functions (CCDFs) representing integrated radionuclide release to the water table indicate that differences in the basic assumptions used to develop conceptual models can have a significant impact on the estimated performance of the site. Because each of the conceptual models employed the same mathematical and numerical models, contained the same data and parameter values and ranges, and did not consider the possible future states of the system, changes in the CCDF could be attributed primarily to differences in conceptual modeling assumptions. Studies such as this one could help prioritize site characterization activities by identifying critical and uncertain assumptions used in model development, thereby providing guidance as to where reduction of uncertainty is most important.
The tectonics program for the proposed high-level nuclear waste repository at Yucca Mountain in southwestern Nevada must evaluate the potential for surface faulting beneath the prospective surface facilities. To help meet this goal, Quaternary surficial mapping studies and photolineament analyses were conducted to provide data for evaluating the location, recency, and style of faulting with Midway Valley at the eastern base of Yucca Mountain, the preferred location of these surface facilities. This interim report presents the preliminary results of this work.
The scanning electron microscope (SEM) has become as standard a tool for IC failure analysis as the optical microscope, with improvements in existing SEM techniques and new techniques being reported regularly. This tutorial has been designed to benefit both novice and experienced failure analysts by reviewing several standard as well as new SEM techniques used for failure analysis. Advanced electron-beam test systems will be covered briefly; however all techniques discussed may be performed on any standard SEM. Topics to be covered are (1) standard techniques: secondary electron imaging for surface topology, voltage contrast, capacitive coupling voltage contrast, backscattered electron imaging, electron beam induced current imaging, and x-ray microanalysis and (2) new SEM techniques: novel voltage contrast applications, resistive contrast imaging, biased resistive contrast imaging, and charge-induced voltage alteration. Each technique will be described in terms of the information yielded, the physics behind technique use, any special equipment and/or instrumentation required to implement the technique, the expertise required to implement the technique, possible damage to the IC as a result of using the technique, and examples of using the technique for failure analysis.
