Sandia now has the capability to evaluate stresses during cure of epoxies with finite element codes. Numerous material parameters are needed as input to these codes. I present a relatively quick set of tests which enable evaluation of the required thermophysical properties. Ease and accuracy of the tests improve as the reaction rate of the thermoset slows. Material parameters for common encapsulants at Sandia are presented in tables.
Six boreholes were drilled during the geologic characterization and diagnostics of the Weeks Island sinkhole that is over the two-tiered salt mine which was converted for oil storage by the U.S. Strategic Petroleum Reserve. These holes were drilled to provide for geologic characterization of the Weeks Island Salt Dome and its overburden in the immediate vicinity of the sinkhole (mainly through logs and core); to establish a crosswell configuration for seismic tomography; to establish locations for hydrocarbon detection and tracer injection; and to provide direct observations of sinkhole geometry and material properties. Specific objectives of the logging program were to: (1) identify the top of and the physical state of the salt dome; (2) identify the water table; (3) obtain a relative salinity profile in the aquifer within the alluvium, which ranges from the water table directly to the top of the Weeks Island salt dome; and (4) identify a reflecting horizon seen on seismic profiles over this salt dome. Natural gamma, neutron, density, sonic, resistivity and caliper logs were run.
An analytical and experimental study is conducted to investigate the effect of isolator locations on the effectiveness of vibration isolation systems. The study uses isolators with fixed properties and evaluates potential improvements to the isolation system that can be achieved by optimizing isolator locations. Because the available locations for the isolators are discrete in this application, a Genetic Algorithm (GA) is used as the optimization method. The system is modeled in MATLAB{trademark} and coupled with the GA available in the DAKOTA optimization toolkit under development at Sandia National Laboratories. Design constraints dictated by hardware and experimental limitations are implemented through penalty function techniques. A series of GA runs reveal difficulties in the search on this heavily constrained, multimodal, discrete problem. However, the GA runs provide a variety of optimized designs with predicted performance from 30 to 70 times better than a baseline configuration. An alternate approach is also tested on this problem: it uses continuous optimization, followed by rounding of the solution to neighboring discrete configurations. Results show that this approach leads to either infeasible or poor designs. Finally, a number of optimized designs obtained from the GA searches are tested in the laboratory and compared to the baseline design. These experimental results show a 7 to 46 times improvement in vibration isolation from the baseline configuration.
This work addresses specification and design of reliable safety-critical systems, such as nuclear reactor control systems. Reliability concerns are addressed in complimentary fashion by different fields. Reliability engineers build software reliability models, etc. Safety engineers focus on prevention of potential harmful effects of systems on environment. Software/hardware correctness engineers focus on production of reliable systems on the basis of mathematical proofs. The authors think that correctness may be a crucial guiding issue in the development of reliable safety-critical systems. However, purely formal approaches are not adequate for the task, because they neglect the connection with the informal customer requirements. They alleviate that as follows. First, on the basis of the requirements, they build a model of the system interactions with the environment, where the system is viewed as a black box. They will provide foundations for automated tools which will (a) demonstrate to the customer that all of the scenarios of system behavior are presented in the model, (b) uncover scenarios not present in the requirements, and (c) uncover inconsistent scenarios. The developers will work with the customer until the black box model will not possess scenarios (b) and (c) above. Second, the authors will build a chain of several increasingly detailed models, where the first model is the black box model and the last model serves to automatically generated proved executable code. The behavior of each model will be proved to conform to the behavior of the previous one. They build each model as a cluster of interactive concurrent objects, thus they allow both top-down and bottom-up development.
Effectiveness and efficiency of software development can be greatly increased by writing modularized code using informal (styles) and formal (standards) work approaches. Software development is about connecting pieces into a coherent whole. Thus consistent work approaches provide a structure that allows individuals and teams to minimize the time and thought put into making these connections. These investments in structure return even more benefits in the maintenance phase when old code has to be examined by new programmers, or after time has passed. We present some examples of coding style for Avenue: a simplified form of Hungarian notation (notationHungarian, stringCustomerName, etc.), script naming prefixes and suffixes, and options in script headers. We demonstrate several modular, object-like utility scripts that can be used alone or combined into other utilities. These include developer tools such as a System.Echo substitute for Windows, a Window inspector, and a script for detecting and dealing with multiple display resolutions.
We present an in situ technique for monitoring metal-organic vapor phase epitaxy growth by normal-incidence reflectance. This technique is used to calibrate the growth rate periodically and to monitor the growth process routinely. It is not only a precise tool to measure the growth rate, but also very useful in identifying unusal problems during a growth run, such as depletion of source material, deterioration of surface morphology, and problems associated with an improper growht procedure. We will also present an excellent reproducibility ({+-}0.3% over a course of more than 100 runs) of the cavity wavelength of vertical-cavity surface emitting laser structures with periodic calibration by this in situ technique.
Electronic and electrical system protection design can be used to eliminate deleterious effects from lightning, electromagnetic interference, and electrostatic discharges. Evaluation of conventional lightning protection systems using advanced computational modeling in conjunction with rocket-triggered lightning tests suggests that currently used lightning protection system design rules are inadequate and that significant improvements in best practices used for electronic and electrical system protection designs are possible. A case study of lightning induced upset and failure of a railway signal and control system is sketched.
How can the public play a role in decisions involving complicated scientific arguments? This paper describes a public participation exercise in which stakeholders used multiattribute utility analysis to select a site for a hazardous waste facility. Key to success was the ability to separate and address the two types of judgements inherent in environmental decisions: technical judgements on the likely consequences of alternative choices and value judgements on the importance or seriousness of those consequences. This enabled technical specialists to communicate the essential technical considerations and allowed stakeholders to establish the value judgements for the decision. Although rarely used in public participation, the multiattribute utility approach appears to provide a useful framework for the collaborative resolution of many complex environmental decision problems.
Two polyurethane systems, EN-7 and L-100, have a long history as encapsulants and coatings in Sandia programs. These materials contain significant amounts of toluene diisocyanate (TDI), a suspect human carcinogen. As part of efforts to reduce the use of hazardous materials in the workplace, PET-90A, a polyurethane with less than 0.1% free TDI, was identified as a candidate for new applications and as a replacement for the more hazardous polyurethanes in selected programs. This report documents the results of a two-year accelerated aging study of PET-90A, EN-7, and L-100 polyurethane elastomers to characterize the effect of 135{degrees}F isothermal aging on selected physical, electrical, mechanical and thermal properties. In general, there was very little change in properties over the two year period for the three elastomers. The largest changes occurred in EN-7, which is the polyurethane with the longest service history in Sandia applications.
Vector network analyzers provide a convenient way to measure scattering parameters of a variety of microwave devices. However, these instruments, unlike oscilloscopes, require a high degree of user knowledge and expertise. Measurement calibration or error correction must be done prior to use. There are many ways to make poor measurement or measurement. Check standards have been used to verify that the network analyzer is operating properly. A computer program was developed to automatically measure a check standard and compare the new measurements with an historical database of measurements of the check standard device. The program can acquire new measurement data from selected check standards, plot the new data against the mean and standard deviation of prior data for the check standard, and update the database files for the check standard. This paper describes the function of the software including a discussion of its capabilities. The way in which the software is used in our lab is also described. Finally, examples are given of how the software can detect potential measurement problems.
Fe/KClO{sub 4} pyrotechnic mixtures are used in thermal batteries to provide the heat necessary to bring the battery stack to operating temperatures of 550 to 600 C. This heat source is normally used as discs pressed from bulk powder. To evaluate the consequences associated with unexpected ignition of large amounts of heat powder, combustion of 84% Fe/16% KClO{sub 4} heat powders was conducted for various scenarios under controlled conditions and the response documented. Increasing amounts of heat powder--up to 8 lbs--were ignited in both unconfined and confined (sealed) containers in a remote area. The containers were thermocoupled and the resulting burning filmed with a standard video camera, high-speed (1,000 frames/s) film and video cameras, and an infrared video camera. A 20- minute video of the burning under the various conditions is presented.
Sandia`s Risk Management and NEPA Department recognized the need for hazard and environmental data analysis and management to support the line managers` need to know, understand, manage and document the hazards inherent in their facilities and activities. ISEEMS (Integrated Safety, Environmental, & Emergency Management System) was developed in response to this need. ISEEMS takes advantage of the fact that there is some information needed for the NEPA process that is also needed for the safety documentation process. The ISEEMS process enables Sandia to identify and manage hazards and environmental concerns at a level of effort commensurate with the hazards themselves by adopting a necessary and sufficient (graded) approach to compliance. The Preliminary Hazard Screening module of ISEEMS determines the facility or project activity hazard classification and facility designation. ISEEMS` geo-referenced icon allows immediate, visual integration of hazard information across geographic boundaries resulting in significant information compression. At Sandia, ISEEMS runs on the Sandia Internal Restricted Network, in an MS-Windows environment on standard PC hardware. The possibility of transporting ISEEMS to a ``WEB-like`` environment is being explored.
This paper presents a paradigm for integrating the many facets of ES&H management based on the necessary and sufficient control of hazards and the resulting risks through a systems approach. The paradigm answers the question ``What is the best approach to managing ES&H to increase value, reduce risk, and improve satisfaction?`` Hazard identification is the foundation of integrated ES&H management. Knowledge of risk is essential to the necessary and sufficient management of risk. A systems approach to identifying and managing risks is essential in achieving integrated ES&H management. Feedback is discussed. The objectives can be applied to the function of risk management using the ``Know, Understand, Manage and Document`` paradigm. The organizational structure is crucial to the success of integrated ES&H management.
The thermal response under geothermal-borehole conditions of a conventional thermal battery was evaluated for various designs by numerical simulations using a finite-element thermal model. This technology, which is based on molten salts, may be suitable as a power source for geothermal borehole applications for data logging. Several promising candidate electrolytes were identified for further study.
Three constitutive models are recommended as candidates for describing the deformation of crushed salt. These models are generalized to three-dimensional states of stress to include the effects of mean and deviatoric stress and modified to include effects of temperature, grain size, and moisture content. A database including hydrostatic consolidation and shear consolidation tests conducted on Waste Isolation Pilot Plant (WIPP) and southeastern New Mexico salt is used to determine material parameters for the models. To evaluate the capability of the models, parameter values obtained from fitting the complete database are used to predict the individual tests. Finite element calculations of a WIPP shaft with emplaced crushed salt demonstrate the model predictions.
A post-processing, selective micro-chemical vapor deposition (``micro-CVD``) technology for the deposition of catalytic films on surface-micromachined, nitride-passivated polysilicon filaments has been investigated. Atmospheric pressure deposition of Pt on microfilaments was accomplished by thermal decomposition of Pt acetylacetonate; deposition occurs selectively only on those filaments which are electrically heated. Catalyst morphology, characterized by SEM, can be controlled by altering deposition time, filament temperature, and through the use of pulsed heating of the filament during deposition. Morphology plays an important role in determining the sensitivity of these devices when used as combustible gas sensors.
Semiconductor bridges (SCB) igniters were evaluated as possible replacements for conventional hot-wire igniters for use in thermal batteries. The all-fire and no-fire characteristics were determined using an up-down scheme; the Neyer/SENSIT program was used to analyze the data. The SCB igniters functioned with a higher no-fire level, relative to a hot-wire igniter, for a given all-fire level. This makes the SCB igniter safer and more reliable than its hot-wire counterpart. The SCB is very resistant to electrostatic discharge and does not require a sensitization mixture for ignition of the primary pyrotechnic charge. These factors, along with its amenability to large-scale production, make the SCB igniter ideally suited for use in thermal batteries.
Chemical-Mechanical Polishing (CMP) has emerged as an enabling technology for manufacturing multi-level metal interconnects used in high-density Integrated Circuits (IC). In this work we present extension of CMP from sub-micron IC manufacturing to fabrication of complex surface-micromachined Micro-ElectroMechanical Systems (MEMS). This planarization technique alleviates processing problems associated with fabrication of multi-level polysilicon structures, eliminates design constraints linked with non-planar topography, and provides an avenue for integrating different process technologies. We discuss the CMP process and present examples of the use of CMP in fabricating MEMS devices such as microengines, pressures sensors, and proof masses for accelerometers along with its use for monolithically integrating MEMS devices with microelectronics.
3-D quasistatic finite element codes are being used at Sandia to simulate large room and pillar mines in rock salt. The two examples presented in this paper are of mines supported by US DOE, under the auspices of the Strategic Petroleum Reserve program. One of the mines is presently used as an oil storage facility. These simulations, validated by field measurements and observations, have provided valuable insight into the failure mechanisms of room and pillar mines in rock salt. The calculations provided the basis for further investigation and the ultimate decision to decommission the DOE oil storage facility.
A large-scale dynamic compaction demonstration of natural salt was successfully completed. About 40 m{sup 3} of salt were compacted in three, 2-m lifts by dropping a 9,000-kg weight from a height of 15 m in a systematic pattern to achieve desired compaction energy. To enhance compaction, 1 wt% water was added to the relatively dry mine-run salt. The average compacted mass fractional density was 0.90 of natural intact salt, and in situ nitrogen permeabilities averaged 9X10{sup -14}m{sup 2}. This established viability of dynamic compacting for placing salt shaft seal components. The demonstration also provided compacted salt parameters needed for shaft seal system design and performance assessments of the Waste Isolation Pilot Plant.
An issue of paramount interest to US industry is the supply and quality of human resources available for this country`s scientific and technological activities. The changing composition of the workforce and the responsibility that an organization has to assure equal opportunity, give rise to various issues. This paper discusses some of the issues associated with the scientific and technical workforce. Specifically, it explores some of the questions pertaining to workforce composition and measures of workforce composition. This paper should be useful to those responsible for personnel policies.
All valid constitutive equations must satisfy two general invariance principles as well several other principles. In this paper the MDCF (Multimechanism Deformation Coupled Fracture) model for rock salt is shown to be thermodynamically consistent, coordinate invariant, frame indifferent, and physically admissible. Additionally, the stress rates used in the formulation are shown to be kinematically consistent with the Cauchy stress rates.
Over 100 candidates were examined, including commercial materials and many that were synthesized in house. The mixed oxides were based on Ti, V, Nb, Cr, Mo, W, Mn, Fe, Co, Ni, and Cu doped with other transition metals. A number of individual (single-metal) oxides were included for comparison. The candidates were tested in single cells with Li(Si) anodes and separators based on LiCl-KCl eutectic. Screening was done under constant-current conditions at current densities of 125 me/cm{sup 2} and, to a lesser extent, 50 me/cm{sup 2} at 500 C. Relative performance and limitations of the oxide cathodes are discussed.
The performance of PAN-based composite absorbers was evaluated in dynamic experiments at flow rates ranging from 25--100 bed volumes (BV) per hour. Composite absorbers with active components of ammonium molybdophosphate (AMP) PAN and K-Co ferrocyanide (KCoFC) PAN were used for separating Cs from a 1 M HNO{sub 3} + 1 M NaNO{sub 3} + 2 {times} 10{sup {minus}5} M CsCl acidic simulant solution. KCoFC-PAN and two other FC-based composite absorbers were tested for separating Cs from alkaline simulant solutions containing 0.01 M to 1 M NaOH and 1 M NaNO{sub 3} + x {times} 10{sup {minus}4} M CsCl. The efficiency of the Cs sorption on the AMP-PAN absorber from acidic simulant solutions was negatively influenced by the dissolution of the AMP active component. At flow rates of 50 BV/hr, the decontamination factor of about 10{sup 3} could be maintained for treatment of 380 BV of the feed. With the KCoFC-PAN absorber, the decontamination factor of about 10{sup 3} could be maintained for a feed volume as great as 1,800 BV. In alkaline simulant solutions, significant decomposition of the active components was observed, and the best performance was exhibited by the KCoFC-PAN absorber. Introductory experiments confirmed that Cs may be washed out of the composite absorbers. Regeneration of both absorbers for repetitive use was also found to be possible. The main result of the study is that PAN was proven to be a versatile polymer capable of forming porous composite absorbers with a large number of primary absorbers. The composite absorbers proved to be capable of withstanding the harsh acidic and alkaline conditions and significant radiation doses that may be expected in the treatment of US DOE wastes. A field demonstration is proposed as a follow-on activity.