Polyurethane foams are dispensed into firesets to protect their electrical integrity under extreme environmental conditions. Although the production process has generally high precision, reliability problems have been identified. Preliminary results from a research program involving the use of rapid infrared sensors combined with multivariate analysis to monitor the blend of raw materials in near real time are presented. Two distinct regions of the infrared spectrum are considered. The mid infrared region is shown to make sufficiently precise concentration predictions while the near infrared region will require more experimentation. Both infrared regions will be considered for pilot and/or plant scale studies in order to completely specify the infrared sensor. The concentration predictions from the infrared sensor will be used in a closed loop control system in order to improve the reliability of the process.
This report discusses the cycloaliphatic epoxide that is UV cured to create protective coatings. Mechanical and electrical properties are briefly discussed.
Sandia National Laboratories is currently assessing whether the Waste Isolation Pilot Plant (WIPP) complies with the Environmental Protection Agency's Environmental Standards for the Management and Disposal of Spent Nuclear Fuel, High-Level, and Transuranic Radioactive Wastes. Assessing compliance of a geologic repository requires the use of many different types of computer modeling programs. For this task, Sandia is developing a controller, CAMCON (Compliance Assessment Methodology CONtroller), which is a software package consisting of a suite of procedural files that control the flow of data between a computational data base and various modeling programs. CAMCON prompts the analyst for specifics about modeling needs, such as code name(s) and number of runs, thus providing a flexible, yet semi-automated framework in which analysts can select the code(s) best suited for a particular problem. CAMCON also incorporates quality assurance features.
A dynamic finite element analysis was performed to study the penetration mechanics of a commercial fastener called Metal-Tack{reg sign}. This study evaluated the fastener and identified parametric changes required for attachment to AISI 1070 steel (R{sub c} = 26), a material harder than the fastener was designed for. A set of baseline calculations was performed to evaluate the fastener's performance in yellow brass, a much softer material. The analysis indicated that a driving energy of 3.03 ft{center dot}lbs was required to drive the tack into yellow brass. Excellent correlation of this model with experimental data provided confidence for applying the model to AISI 1070 steel. Tack performance was investigated with respect to variations in driving energy and tack strength. The results demonstrated that increasing driving energy was not sufficient for a successful attachment in the steel. An increase in tack strength was also required. Higher tack strength was obtained by increasing the heat treat specification of the tack material, Carpenter R.D.S. steel, to obtain a hardness of R{sub c} = 60. With this increase in strength and a driving energy of 20.8 ft{center dot}lb, the results indicated that the tack would attach but develop high plastic strain (21.5%) during attachment. The calculations were confirmed with tests using a high energy pyrotechnic driver developed to attach the tack. Finally, a geometry modification intended to reduce stress concentrations in the tack was evaluated experimentally but not computationally. The experimental results indicated an improvement in the tack strength and attachment quality. 4 refs., 19 figs., 4 tabs.
This report describes an automatic calibration system used in the calibration of all precision AC calibrators. The system includes an AC-DC Transfer Standard, a DC Voltage Standard, and a high-resolution digital multimeter, with an IBM-XT Personal Computer for data acquisition and analysis. Specialized instrumentation and measurement techniques make it possible to achieve high accuracy measurements with repeatability. 5 refs., 3 figs.
The Formerly Utilized Sites Remedial Action Program has updated an extensive objective concentration factor and biological half-life data base from the international marine radioecological literature. A microcomputer-based data management system has been implemented to provide statistical and graphic summaries of these data. The data base is constructed in a manner which allows subsets to be sorted using a number of interstudy variables such as organism category, tissue/organ category, geographic location (for in situ studies), and several laboratory-related conditions (e.g., exposure time and exposure concentrator). This report updates earlier reviews, and provides summaries of the tabulated data. In addition to the concentration factor/biological half-life data base, we provide an outline of other published marine radioecological works. Our goal is to present these data in a form that enables those concerned with predictive assessment of radiation dose in the marine environment to make a more judicious selection of data for a given application. 588 refs., 18 figs., 3 tabs.
This document describes the NEFTRAN II (NEtwork Flow and TRANsport in Time-Dependent Velocity Fields) computer code and is intended to provide the reader with sufficient information to use the code. NEFTRAN II was developed as part of a performance assessment methodology for storage of high-level nuclear waste in unsaturated, welded tuff. NEFTRAN II is a successor to the NEFTRAN and NWFT/DVM computer codes and contains several new capabilities. These capabilities include: (1) the ability to input pore velocities directly to the transport model and bypass the network fluid flow model, (2) the ability to transport radionuclides in time-dependent velocity fields, (3) the ability to account for the effect of time-dependent saturation changes on the retardation factor, and (4) the ability to account for time-dependent flow rates through the source regime. In addition to these changes, the input to NEFTRAN II has been modified to be more convenient for the user. This document is divided into four main sections consisting of (1) a description of all the models contained in the code, (2) a description of the program and subprograms in the code, (3) a data input guide and (4) verification and sample problems. Although NEFTRAN II is the fourth generation code, this document is a complete description of the code and reference to past user`s manuals should not be necessary. 19 refs., 33 figs., 25 tabs.
The spatial correlation structure of volcanic tuffs at and near the site of the proposed high-level nuclear waste repository at Yucca Mountain, Nevada, is estimated using samples obtained from surface outcrops and drill holes. Data are examined for four rock properties: porosity, air permeability, saturated hydraulic conductivity, and dry bulk density. Spatial continuity patterns are identified in both lateral and vertical (stratigraphic) dimensions. The data are examined for the Calico Hills tuff stratigraphic unit and also without regard for stratigraphy. Variogram models fitted to the sample data from the tuffs of Calico Hills indicate that porosity is correlated laterally over distances of up to 3000 feet. If air permeability and saturated conductivity values are viewed as semi-interchangeable for purposes of identifying spatial structure, the data suggest a maximum range of correlation of 300 to 500 feet without any obvious horizontal to vertical anisotropy. Continuity exists over vertical distances of roughly 200 feet. Similar variogram models fitted to sample data taken from vertical drill holes without regard for stratigraphy suggest that correlation exists over distances of 500 to 800 feet for each rock property examined. Spatial correlation of rock properties violates the sample-independence assumptions of classical statistics to a degree not usually acknowledged. In effect, the existence of spatial structure reduces the ``equivalent`` number of samples below the number of physical samples. This reduction in the effective sampling density has important implications for site characterization for the Yucca Mountain Project.
The US Department of Energy (DOE) is responsible for designing, obtaining a license for, and constructing a geologic repository for the disposal of commercial high-level radioactive waste. The candidate repository site is currently at Yucca Mountain in Nevada. Part of DOE`s responsibility is to assess compliance with the appropriate environmental regulations, including the Environmental Protection Agency`s containment requirements in 40 CFR Part 191. Sandia National Laboratories (SNL) and Pacific Northwest Laboratories (PNL) have been contracted to aid DOE in the assessment of total systems performance. SNL has been tasked with evaluating and comparing the performance assessment methodologies developed by PNL and SNL, as applied to one conceptual model. In this report, SNL has attempted to reproduce, by way of a benchmark exercise, the results of PNL`s preliminary risk assessment of the proposed repository at Yucca Mountain. In general, the results of the PNL analysis and the SNL benchmark of that analysis agreed quite well, in terms of both ground-water flow and transport of unretarded radionuclides. The largest discrepancy between the analyses was noted for transport of retarded radionuclides, and was the result of different techniques for calculating retardation factors. 27 refs., 28 figs., 17 tabs.
The objective of this work is to develop a general method for remotely sensing the presence of tunneling activities using one or more boreholes and a combination of surface sources. New techniques for tunnel detection and location of tunnels containing no metal and of tunnels containing only a small diameter wire have been experimentally demonstrated. A downhole magnetic dipole and surface loop sources were used as the current sources. The presence of a tunnel causes a subsurface scattering of the field components created by the source. Ratioing of the measured responses enhanced the detection and location capability over that produced by each of the sources individually. 4 refs., 18 figs., 2 tabs.
The gas-generation characteristics of contact-handled transuranic waste from Rocky Flats Plant (RFP) and Idaho National Engineering Laboratory (INEL) will be tested at the Waste Isolation Pilot Plant (WIPP) in a series of bin-scale experiments. Bin-scale experiments are necessary because the extreme heterogeneity of CH TRU waste precludes adequate simulation of the waste in the laboratory. A stratified random sample of waste drums will be selected from the collection of drums at RFP and INEL that can be certified for shipment to the WIPP by August 1991. Before the waste is emplaced in the bins, 11 physical characteristics expected to control gas- generation behavior will be measured. These 11 controlling variables'' are expected to apply to all existing and future transuranic waste throughout the Department of Energy complex. Experiments will examine gas generation by radiolysis, microbial degradation, corrosion, and any synergistic mechanisms under many of the environmental conditions that will or may occur in the WIPP repository during the next 10,000 years. Because gas-generation behavior will be interpreted in terms of the controlling variables, gas generation by existing RFP/INEL waste that is not currently shippable, existing waste at other sites, and future waste can be predicted from the results of the WIPP bin-scale experiments. The results of the bin-scale experiments will support the WIPP Project's evaluation of compliance with 40 CFR 191, 40 CFR 268, and the National Environmental Policy Act.
A series of impact experiments on polymethyl methacrylate (PMMA) manufactured by Polycast Technology Corporation has recently been completed using a light gas gun. The intent of this work was to compare these Hugoniot data with those data from a previous study on PMMA manufactured by Rohm and Haas. The results show that there are no significant differences in Hugoniot parameters for the two materials in the pressure range of 1.9 to 6.9 GPa. 8 refs., 10 figs., 3 tabs.
This report describes the current status and recent progress in the Advanced Handling Technology Project (AHTP) initiated to explore the use of advanced robotic systems and handling technologies to perform automated cask handling operations at radioactive waste handling facilities, and to provide guidance to cask designers on the impact of robotic handling on cask design. Current AHTP tasks have developed system mock-ups to investigate robotic manipulation of impact limiters and cask tiedowns. In addition, cask uprighting and transport, using computer control of a bridge crane and robot, were performed to demonstrate the high speed cask transport operation possible under computer control. All of the current AHTP tasks involving manipulation of impact limiters and tiedowns require robotic operations using a torque wrench. To perform these operations, a pneumatic torque wrench and control system were integrated into the tool suite and control architecture of the gantry robot. The use of captured fasteners is briefly discussed as an area where alternative cask design preferences have resulted from the influence of guidance for robotic handling vs traditional operations experience. Specific robotic handling experiences with these system mock-ups highlight a number of continually recurring design principles: (1) robotic handling feasibility is improved by mechanical designs which emphasize operation with limited dexterity in constrained workspaces; (2) clearances, tolerances, and chamfers must allow for operations under actual conditions with consideration for misalignment and imprecise fixturing; (3) successful robotic handling is enhanced by including design detail in representations for model-based control; (4) robotic handling and overall quality assurance are improved by designs which eliminate the use of loose, disassembled parts. 8 refs., 15 figs.
The Pre-Tiger Team Self-Assessment (PTTSA) Report identified findings with respect to the way Sandia National Laboratories (SNL), Albuquerque, (including Tonopah Test Range (TTR) and Kauai Test Facility (KTF)) conducts its environment, safety, and health (ES H) activities. It presented Action Plan Requirements (APR) addressing these findings. The purpose of this PTTSA Action Plan Report is to assist in managing these action plan requirements by collecting, prioritizing, and estimating required resources. The specific objectives addressed by this report include: collection of requirements for the resolution of the findings presented in the PTTSA Report; consolidation of proposed Action Plan Requirements into logical Action Plan groupings for efficiency of resolution; categorization of Action Plans according to severity of the hazards represented by the findings; provision of a basis for long-range planning and issues management; documentation of the status of the proposed corrective actions; establishment of traceability of the corrective action to the original problem or issue; and integration of these plans into the existing ES H structure. The Action Plans in this report are an intermediate step between the identification of a problem or a finding in the PTTSA Report and the execution of the solution. They consist of requirements for solution, proposed actions, and an estimate of the time and (where applicable) resources required to develop the solution. This report is an input to the process of planning, resource commitment, development, testing, implementation, and maintenance of problem resolution. 2 figs.
This handbook outlines the basic job of guest editors for the HEART Conference proceedings, published by the DoD Nuclear Information and Analysis Center in the Journal of Radiation Effects, Research and Engineering. Suggestions are offered for procedures to aid the editors, authors, reviewers, and the publisher in assuring that the journal communicates clearly, concisely, and honestly.
The output intensity of a laser can be expressed in the form I{sub out} = Ag{sub 0}I{sub s} + BI{sub s}. The constants A and B are independent of the pump rate for laser systems with nonsaturable losses, but both g{sub 0}I{sub s} and I{sub s} can depend upon the pump rate. Methods for determining the pump rate dependence of g{sub 0}I{sub s} and I{sub s} are given for experiments in which the pump rate varies continuously. 6 refs., 1 fig.
A towed linear hydrophone array is subject to snakelike bending. If the array were processed as if it were truly linear, poor array gain coupled with a degraded source bearing estimate would result. The signal phase errors produced by sensor position uncertainty in passive sonar arrays are similar to those observed in Synthetic Aperture Radar (SAR) imagery. The Phase Gradient Autofocus (PGA) Algorithm has been shown to be a robust and effective method used to extract degrading phase errors prevalent in SAR imagery. This report shows that with slight modifications, the PGA algorithm can be applied to correct phase errors resulting from sensor position uncertainty introduced into linear-passive arrays. The results of the technique applied to simulated linear array data is also presented. 9 refs., 8 figs.
As part of Sandia National Laboratories` (SNL) pollution prevention program a system is under development to track the movement of hazardous and radioactive materials from procurement, through use, to final disposition. The information provided by this system will improve the flow and enhance the quality of data, avoid duplication of effort, facilitate timely and accurate reporting, better support the information needs of various Environmental, Safety, and Health (ES&H) programs, and allow waste to be minimized more effectively. Such a comprehensive system will incorporate information from other sources and build upon existing databases. The component include the Chemical Information System/Material Safety Data Sheet (CIS/MSDS) system installed by AT&T Bell Laboratories (AT&T-BL) at SNL in Livermore, along with a barcode chemical waste tracking system already in operation at SNL in Albuquerque. Also being developed in Albuquerque are Process Waste Assessments, a radioactive material tracking system, and a radioactive/mixed waste tracking system. A SNL and AT&T-BL joint project is addressing how PWAs will link raw materials to waste streams. With a ``cradle-to-grave`` tracking system, it is possible to assess both financial and environmental life cycle costs. Once in place, this information will improve long-run efficiency and environmental protection, and provide benefits exceeding the initial demands placed upon personnel.
Tests have been conducted on bench-scale heat-pipe solar receivers to explore methods of constructing wicks. The primary objective was to develop a wick structure that was easy to fabricate and was capable of transporting liquid sodium over long distances against hydrostatic and frictional pressure drops. One of the wicks tested in this program was able to lift sodium 45 cm by capillary pumping alone to cool a 3-cm×10-cm area subjected to an average flux of 50 W/cm2.
Knowledge of the solubility of gases in pure water and sodium chloride brine is required for the evaluation of gas-liquid behavior associated with numerous processes in the chemical, biological, and geological sciences and in chemical engineering. Modelling of multiphase flow and transport processes used to simulate fluid behavior in geological media requires suitable and accurate gas solubility data, especially when applied to potential nuclear waste repositories such as WIPP. This report contains a critical evaluation of data available in the literature and provides compiled data sets for the solubility of hydrogen, nitrogen, methane, and carbon dioxide gases in pure water and in sodium chloride brine. Mole fraction gas solubilities are presented as functions of temperature and pressure. To evaluate the influence of electrolyte content of the aqueous solution upon the gas solubility, Sechenov coefficients are provided for several concentrated sodium chloride solution. An estimate of the solubility of hydrogen in 5 N sodium chloride brine as a function of pressure exhibits a solubility at 40 MPa that is one fifth the value observed for pure water at the same pressure.
In this paper, a design methodology is presented for assessing drift stability for a potential high-level radioactive waste repository. Excavation stability is required during construction, emplacement, retrieval (if required) and closure phases to ensure worker health and safety, and to prevent development of potential pathways for radionuclide migration in the post-closure period. Requirements for the design, site conditions and stresses are considered in the methodology. Methods for evaluating empirical and analytical results in order to estimate ground support requirements are outlined.
There are three aspects to an environmentally safe battery. The first deals with the manufacturing process, the second with the use of environmentally friendly materials, and the third with the disposal and/or recycling of spent units. In this paper, several ongoing programs at Sandia National Laboratories that relate to the environmentally conscious manufacturing of batteries, are discussed. The solvent substitution/elimination program is a two-pronged effort, aimed at identifying new solvents which are compatible with the environment, while at the same time developing dry process cleaning technology. The joining program is evaluating new solvents for flux removal as well as the development of fluxless soldering processes. In the area of welding, new cleaning processes are under study. Chemical microsensors are under development that are capable of identifying and quantifying single chemical species. These sensors have been used to monitor and improve processes using toxic/hazardous solvents. 1 ref., 1 fig.
Phased-array antenna systems are well known for rapid beam steering and their ability to bring high power to the target. Such systems are also quite complex and heavy, which have limited their usefulness. The issues of weight, size, power use, and complexity have been addressed through a system named COMPASS (Coherent Optical Monolithic Phased Array Steering System). All phased-array antenna systems need: (1) small size; (2) low power use; (3) high-speed beam steering; and (4) digitally-controlled phase shifting. COMPASS meets these basic requirements, and provides some very desirable additional features. These are: (1) phase control separate from the transmit/receive module; (2) simple expansion to large arrays; (3) fiber optic interconnect for reduced sensitivity to EMI; (4) an intrinsically radiation-hard GaAs chip; and (5) optical power provided by a commercially available continuous wave (CW) laser. 4 refs., 8 figs.
Titanium alloys offer desirable properties that make them attractive candidates for tribological applications. Their surface-related properties, however, such as coefficient of friction and wear rate, are less than optimum and must be improved by surface modification. To increase the tribological properties of Ti-6Al-4V, a high temperature ion implantation method, employing a high current density beam (e.g., 500 {mu}A/cm{sup 2}) of nitrogen (N) ions is being developed, where surface temperatures greater than 1000{degrees}C can be obtained. A systematic study was performed with N implantation at temperatures from 400{degrees} to >1000{degrees}C, and to a range of doses from 0.1--1.0{times}10{sup 18} N{sub 2}{sup +}--N{sup +}/cm{sup 2}. Microstructure characterization by Rutherford Backscattering Spectroscopy (RBS) and Glancing Incidence X-ray Diffraction (GID) was performed to determine N distribution and compound formation. RBS analysis showed enhanced N penetrations (i.e., greater than 0.3 {mu}m) for the 800{degrees} and 1000{degrees}C implantations, with the deepest penetration (about 3.5 atomic percent N remaining at 0.75 {mu}m) for the 1000{degrees}C treatment. GID indicated TiN and Ti{sub 2}N concentrations were the greatest for the 800{degrees}C implantation treatment. 11 refs., 4 figs.
The debonding rates of H-passivated P and As in silicon have been observed to be very sensitive to the concentration of majority and minority charge carriers. A theoretical study of the stable and metastable configurations of the {l brace}P,H{r brace} and {l brace}As,H{r brace} pairs in the 0 and +1 charge states has been carried out at the near-ab-initio Hartree-Fock level. These calculations show that the lowest-energy configuration in the 0 charge state is the highest-energy configuration in the +1 charge state and vice-versa. This bistability of donor-hydrogen pairs implies that H cannot remain in place upon change of charge state, whether 0 {r arrow} +1 or +1 {r arrow} 0. Quantitative differences between the P and the As cases are qualitatively consistent with the observed differences in the temperature dependence of the debonding rates of {l brace}P,H{r brace} and {l brace}As,H{r brace}. 14 refs., 1 fig.
The usefulness of neutron radiography as a nondestructive engineering tool is heavily dependent on how a neutron reaches the image plane. Neutron interactions such as scattering and absorption, within a neutron radiography facility or a test part, affect the contrast of the resulting image generated by the process. It is important that the radiographer has a general understanding of how neutrons interact with matter to produce a quality image utilizing a neutron beam. 4 refs.
Conference Record - 7th Biennial IEEE-USA Careers Conference: Change and Competitiveness and Careers
Cannon, Thomas
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.
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 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.
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.
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.
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.
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.
For several years Phillips Petroleum Company has been waterflooding portions of the Ekofisk Field reservoir for purposes of enhanced oil recovery. Boreholes drilled in waterflooded portions of the reservoir have encountered poor core recoveries and highly fractured rock (poor core recoveries and highly fractured zones were not uncommon in the Ekofisk reservoir before waterflooding, however). Results of laboratory compression tests designed to simulate production-related compaction and subsequent waterflooding indicate that injection pressures currently used to inject seawater into the reservoir are high enough to induce shear failure in high porosity reservoir chalks. A model of chalk deformation explains brittle failure of chalk that has been subjected to stresses well in excess of yield stress.
The Sandia National Laboratories Pre-Tiger Team Self-Assessment Report contains an introduction that describes the three sites in Albuquerque, New Mexico, Kauai, Hawaii, and Tonopah, Nevada, and the activities associated therewith. The self-assessment was performed October 1990 through December 1990. The paper discusses key findings and root causes associated with problem areas; environmental protection assessment with respect to the Clean Air Act, Clean Water Act, Comprehensive Environmental Response, Compensation, and Liability Act and the Superfund amendments, Resource Conservation and Recovery Act; and other regulatory documents; safety and health assessment with respect to organization administration, quality assurance, maintenance, training, emergency preparedness, nuclear criticality safety, security/safety interface, transportation, radiation protection, occupational safety, and associated regulations; and management practices assessment. 5 figs. (MHB)
Large two- and three-dimensional simulations of shock wave physics problems constitute a major expense in ongoing research efforts at Sandia National Laboratories. Massively parallel computing may provide a solution. A simplified version of the production hydrocode CTH, in current use at Sandia National Laboratories, has been successfully developed for the Connection Machine. The parallel version, named PCTH, solves problems in multi-fluid shock wave physics. The development of the Connection Machine code is described and initial performance statistics are presented. These are compared with similar results for the CRAY Y-MP and nCUBE2. 7 refs., 3 figs., 1 tab.
A Low Altitude High Speed Cargo (LAHSC) parachute is being developed for deployment at velocities up to 250 knots at 300 ft altitude. The LAHSC parachute will decelerate and turnover a load to a 40 to 60 ft/sec vertical velocity at first vertical at approximately 30 ft AGL. The acceleration limit is 5 g's. Main chute cargo extraction will be necessary. A single parachute will be utilized for a 7500 lb load, and clusters will be used for larger loads. The 64-gore, 70-ft-dia parachute has a ring-slot/solid construction with a flare at the skirt to aid the inflation. This paper describes the parachute, the design process and testing to date. Model parachutes have been tested in wind tunnels and in free flight. A single full-scale parachute has been tested at low speeds with conventional load extraction, and with a vertical trajectory at deployment. 5 refs., 18 figs., 3 tabs.
High-speed water-entry is a very complex, dynamic process. As a first attempt at modeling the process, a numerical solution was developed at Sandia National Laboratories for predicting the forces and moments acting on a body with a steady supercavity, that is, a cavity which extends beyond the base of the body. The solution is limited to supercavities on slender, axisymmetric bodies at small angles of attack. Limited data were available with which to benchmark the axial force predictions at zero angle of attack. Even less data were available with which to benchmark the pitching moment and normal force predictions at nonzero angles of attack. A water tunnel test was conducted to obtain force and moment data on a slender shape. This test produced limited data because of waterproofing problems with the balance. A new balance was designed and a second water tunnel test was conducted at Tracor Hydronautics, Inc. This paper describes the numerical solution, the experimental equipment and test procedures, and the results of the second test. 8 refs., 11 figs.
Proceedings - IEEE International Conference on Robotics and Automation
Hwang, Yong K.
Path planning among movable obstacles is a practical problem that is in need of a solution. An efficient heuristic algorithm is presented that uses a generate-and-test paradigm: a good candidate path is hypothesized by a global planner and subsequently verified by a local planner. In the process of formalizing the problem, a technique for modeling object interactions through contact is presented. The algorithm has been tested on a variety of examples, and was able to generate solutions within 10 s on a 17-MIPS Sun Sparc workstation.
Proceedings - IEEE International Conference on Robotics and Automation
Novak, J.L.; Wiczer, J.J.
A high-resolution capacitive image sensing technique for measuring edge and surface profiles during manufacturing processes has been invented. A prototype device utilizing this technique consists of two 500-μm-diameter electrodes fabricated on a printed circuit board with a 250-μm gap between them. As the device is mechanically scanned over the workpiece, the spatial variations in the edge or surface to be measured interfere with an electric field imposed between the electrodes, altering the mutual capacitance. The sensor functions as a near-field proximity sensor producing range images of surface imperfections. This sensor has been used in applications requiring a preview image of burns on the edge of a machined part and other processes requiring an inspection image after automated deburring operations.
Proceedings - IEEE International Conference on Robotics and Automation
Stansfield, S.A.
A series of haptic exploratory procedures (EPs) implemented for a multifingered, articulated, sensate robot hand is discussed. These EPs are designed to extract specific tactile and kinesthetic information from an object via their purposive invocation by an intelligent robotic system. Taken together, they form an active robotic touch perception system. This system utilizes a PUMA 560 robot arm, a JPL/Stanford robot hand with joint torque sensing in the fingers, a wrist force/torque sensor, and a 256-element spatially resolved fingertip tactile array. The EPs are described, and experimental results are given.
An analysis is made of the experimental results of a minimum-time trajectory control scheme for a two-link flexible robot. An offline optimization routine determines a minimum-time, straight-line tip trajectory which stays within the torque constraints of the motors and ends with no vibrational transients. An efficient finite-element model is used in the optimization to approximate the flexible arm dynamics. The control strategy described is used to determine the feedback gains for the position, velocity, and strain gage signals from a quadratic cost criterion based on the finite-element model linearized about the straight-line tip trajectory. These feedback signals are added to the modeled torque values obtained from the optimization routine and used to control the robot arm actuators. The results indicate that this combination of model-based and error-driven control strategies achieves a closer tracking of the desired trajectory and a better handling of modeling errors than either strategy alone.