Publications

The thickness-shear mode (TSM) resonator typically consists of a thin disk of AT-cut quartz with circular electrodes patterned on both sides. An RF voltage applied between these electrodes excites a shear mode mechanical resonance when the excitation frequency matches the crystal resonant frequency. When the TSM resonator is operated in contact with a liquid, the shear motion of the surface generates motion in the contacting liquid. The liquid velocity field, v{sub x}(y), can be determined by solving the one-dimensional Navier-Stokes equation. Newtonian fluids cause an equal increase in resonator motional resistance and reactance, R{sub 2}{sup (N)} = X{sub 2}{sup (N)}, with the response depending only on the liquid density-viscosity product ({rho}{eta}). Non-Newtonian fluids, as illustrated by the simple example of a Maxwell fluid, can cause unequal increases in motional resistance and reactance. For the Maxwell fluid, R{sub 2}{sup (M)} > X{sub 2}{sup (M)}, with relaxation time {tau} proportional to the difference between R{sub 2}{sup (M)}and X{sub 2}{sup (M)}. Early results indicate that a TSM resonator can be used to extract properties of non-Newtonian fluids.

This work examined self-assembled monolayers (SAMs) of n-alkane thiols using quartz resonators to determine the shear storage and loss moduli. Network analyzer measurements of electrical admittance at fundamental and corresponding harmonic values are fit to an equivalent circuit model. Shear modulus depends on frequency; the modulus values are three orders of magnitude lower than expected for a liquid or elastomeric polymer, more like those of a dense gas or supercritical fluid. A density of around 0.45 g/cm{sup 3} is calculated for a dodecane thiol SAM; this is roughly half of the bulk density. In conclusion, quartz resonators can be used to inertially deform SAMs.

The feasibility of three different non-destructive and direct methods of evaluating PCB (printed circuit boards) cleanliness was demonstrated. The detection limits associated with each method were established. In addition, the pros and cons of these methods as routine quality control inspection tools were discussed. OSEE (Optically Stimulated Electron Emission) was demonstrated to be a sensitive technique for detection of low levels of flux residues on insulating substances. However, future work including development of rugged OSEE instrumentation will determine whether the PCB industry can accept this technique in a production environment. FTIR (Fourier Transform Infrared) microscopy is a well established technique with well known characteristics. The inability of FTIR to discriminate an organic contaminant from an organic substrate limits its usefulness as a PCB line inspection tool, but it will still remain a technique for the QC/QA laboratory. One advantage of FTIR over the other two techniques described here is its ability to identify the chemical nature of the residue, which is important in Failure Mode Analysis. Optical imaging using sophisticated pattern recognition algorithms was found to be limited to high concentrations of residue. Further work on improved sensor techniques is necessary.

We demonstrate a two-dimensional device simulator for MOSFET structures that incorporates models for defect distributions and show predicted effects on device switching performance for various spatial distributions of defects in amorphous and polycrystalline silicon.

A high temperature resistance furnace has been modified for the study of directional solidification of nickel-base superalloys such as alloys 718 and 625. The furnace will be used to study segregation and solidification phenomena that occur in consumable-electrode melting processes such as vacuum arc remelting and electro-slag remelting. The system consists of a water cooled high temperature furnace (maximum temperature {approximately}2900 C), roughing vacuum,system, cooling system, cooled hearth, molten metal quenching bath, and a mechanism to lower the hearth from the furnace into the molten metal bath. The lowering mechanism is actuated by a digital stopping motor with a programmable controller. The specimen (1.9 cm dia {times} 14 cm long) is melted and contained within an alumina tube (2.54 cm dia {times} 15.24 cm long) which is seated on a copper hearth cooled with {approximately}13 C water. Directional solidification can then be accomplished by decreasing the furnace temperature while holding the specimen in position, maintaining the temperature gradient in the furnace and lowering the specimen at a controlled rate or a combination of both. At any point the specimen can be lowered rapidly into the 70 C molten metal bath to quench the specimen, preserve the solidification structure, and minimize solid state diffusion, enhancing the ability to study the localized solidification conditions.

The design of a software package that provides a variety of Asynchronous Transfer Mode (ATM) test functions is presented here. These functions include cell capture, protocol decode for Transmission Control Protocol/Internet Protocol (TCP/IP) services, removal of cells (to support testing of an ATM system under cell loss conditions), and echo functions. This package is currently written to operate on the Sun Microsystems SPARCstation 10/SunOS 4.1.3 environment with a Fore Systems SBA-100 Sbus ATM adapter (140 Mbit/s TAXI interface), and the DEC 5000/240 running ULTRIX 4.2A with a Fore Systems TCA-100 TurboChannel adapter. Application scenarios and performance measurements of this software package on these host environments are presented here.

Relationships between countries normally war and peace. Crisis prevention activities will be particularly important in this area, and should have two goals: (1) stabilizing tense situations that could push countries toward war and (2) supporting or reenforcing efforts to move countries toward a state of peace. A Crisis Prevention Center (CPC) will facilitate efforts to achieve these goals and its functions can be grouped into three broad, inter-related categories: (1) establishing and facilitating communication among participating countries, (2) supporting negotiations and consensus-building on regional security issues, and (3) supporting implementation of agreed confidence and security building measures. Appropriate activities in each of these categories will depend on the relations among participating countries. Technology will play a critical role in a establishing communication systems to ensure the timely flow of information between countries and to provide the means for organizing and analyzing this information. Technically-based cooperative monitoring can provide an objective source of information on mutually agreed issues, thereby supporting the implementation of confidence building measures and treaties. In addition, technology itself can be a neutral subject of interaction and collaboration between technical communities from different countries. Establishing a CPC in Northeast Asia does not require the existence of an Asian security regime. Indeed, activities that occur under the auspices of a CPC, even highly formalized exchanges of agreed information, can increase transparency, and thereby pave the way for future regional cooperation. Major players in Northeast Asian security are Japan, Russia, China, North and South Korea, and the United States.

Recent research on point defects in thin films of SiO{sub 2} and Si{sub 3}SN{sub 4} on Si is presented and reviewed. In SiO{sub 2} it is now clear that no one type of E{prime} center is the sole source of radiation-induced positive charge; hydrogenous moieties or other types of E{prime} are proposed. Molecular orbital theory and easy passivation of E{prime} by H{sub 2} suggest that released H might depassivate P{sub b} sites. A charged E{prime}{sub {delta}} center has been seen in Cl-free SIMOX and thermal oxide film, and it is reassigned to an electron delocalized over four O{sub 3}{equivalent_to}Si units around a fifth Si. In Si{sub 3}N{sub 4} a new model for the amphoteric charging of Si{equivalent_to}N{sub 3} moieties is based on local shifts in defect energy with respect to the Fermi level, arising from nonuniform composition; it does not assume negative-U electron correlation. A new defect NN{sub 2}{sup 0} has been identified, with dangling orbital on a 2-coordinated N atom bonded to another N.

A parallel unstructured finite element (FE) implementation designed for message passing machines is described. This implementation employs automated problem partitioning algorithms for load balancing unstructured grids, a distributed sparse matrix representation of the global finite element equations and a parallel conjugate gradient (CG) solver. In this paper a number of issues related to the efficient implementation of parallel unstructured mesh applications are presented. These include the differences between structured and unstructured mesh parallel applications, major communication kernels for unstructured CG solvers, automatic mesh partitioning algorithms, and the influence of mesh. partitioning metrics on parallel performance. Initial results are presented for example finite element (FE) heat transfer analysis applications on a 1024 processor nCUBE 2 hypercube. Results indicate over 95% scaled efficiencies are obtained for some large problems despite the required unstructured data communication.

The Leo Brady Seismic Net (LBSN) has been used to estimate seismic yields on US nuclear explosion tests for over 30 years. One of the concerns that Non-Proliferation Experiment (NPE) addresses is the yield equivalence between a large conventional explosion and a nuclear explosion. The LSBN consists of five stations that surround the Nevada Test Site (NTS). Because of our previous experience in measuring nuclear explosion yields, we operated this net to record NPE signals. Comparisons were made with 9 nuclear tests in the same volcanic tuff medium and within an 800 m range of the NPE source. The resulting seismic yield determined by each nuclear test ranged from 1.3 to 2.2 kT. Using the same techniques in determining nuclear explosion yields, the 1 kT NPE was measured at 1.7 kT nuclear equivalent yield with a standard deviation of 16%. The individual stations show a non-symmetric radiation pattern with more energy transmitted to the north and south. Comparisons with an nuclear event does not sow any obvious differences between the two tests.

Law enforcement officers work each day with individuals who can become aggressive and violent. Among the worst scenarios, which occur each year and often raise national media attention, an officer has his handgun taken away and used against him. As many as 12 officers per year are killed with their own gun. This problem can be addressed through the integration of modern sensors with control electronics to provide authorized user firearms for law enforcement and even recreational uses. A considerable benefit to law enforcement agencies, as well as society as a whole, would be gained by the application of recommended Smart Gun Technologies (SGT) as a method of limiting the use of firearms to authorized individuals. Sandia National Laboratory has been actively involved in the research and design of technologically sophisticated surety devices for weapons for the DOE and DOD. This experience is now being applied to criminal justice problems by transferring these technologies to commercial industry. In the SGT project Sandia is developing the user requirements that would limit a firearms use to its owner and/or authorized users. Various technologies that are capable of meeting the requirements are being investigated, these range from biometrics identification to radio-controlled devices. Research is presently underway to investigate which technologies represent the best solutions to the problem. Proof of concept demonstration models are being built for the most promising SGT with the intent of technology transfer. Different solutions are recommended for the possible applications: law enforcement, military, and commercial (personal protection/recreational) use.

This paper describes and discusses a basic safety analysis technique which may be useful for the beginning process of Risk Assessment and Risk Management. The technique uses judgmental factors on the part of analysts rather than dependence upon numerical techniques associated with more detailed analysis. The basic technique is presented and coupled to risk charts which may vary depending upon the intent of the analysis and the output required for the particular situation. Some variations are included to show how the technique may be used for prioritization of competing resources for necessary work.

In addition to stress and acceleration measurements made in the inelastic regime, Sandia fielded two triaxial accelerometer packages in the seismic free-field for the NON-PROLIFERATION EXPERIMENT (NPE). The gauges were located at ranges of 190 and 200 m from the center of the ANFO-laden cavity on the opposite sides of a vertical fault. This location allowed us to assess several different seismological aspects related to non-proliferation. The radial and vertical components of the two packages show similar motion. Comparisons are made with similar data from nuclear tests to estimate yield, calculate seismic energy release and to detect spectral differences between nuclear and non-nuclear explosions. The wave forms of NPE differ significantly from nuclear explosions. The first two peak amplitudes of NPE are comparable while the nuclear explosion initial peak is much larger than the second peak. The calculated seismic energies imply that the conventional explosions couple to the medium much better at low frequencies than do nuclear explosions and that nuclear explosions contain more high frequency energy than NPE. Radial and vertical accelerations were integrated for displacement and indicate there was movement across the fault.

Environmental and toxicity concerns related to the use of lead have initiated the search for acceptable, alternate joining materials for electronics assembly. This paper describes a novel lead-free solder designed as a ``drop in`` replacement for common tin/lead eutectic solder. The physical and mechanical properties of this solder are discussed in comparison to tin/lead eutectic solder. The performance of this solder when used for electronics assembly is discussed and compared to other common solders. Fatigue testing results are reported for thermal cycling electronics assemblies soldered with this lead-free composition. The paper concludes with a discussion on indium metal availability, supply and price.

The core problem with the US health care system is -- it already costs to much and the rate of its cost growth is cause for further alarm. To deal with these, regulators must introduce incentives for health care providers to reduce costs and introduce incentives that make consumers of health care services concerned about the costs of the services they demand. Achievement of these regulatory goals will create opportunities for the introduction of innovations, including revolutionary new technology, that can lead to major reductions in costs. Modeling of health care system inputs, outputs, transactions, and the relationships between these parameters will expedite the development of an effective regulatory process. This model must include all of those major factors that affect the demand for health care and it must facilitate benchmarking health care subsystems against the most efficient international practices.

The response of smooth- and textured-surface thickness-shear mode (TSM) quartz resonators in liquid has been examined. Smooth devices, which viscously entrain a layer of contacting liquid, exhibit a response that depends on the product of liquid density and viscosity. Textured-surface devices, with either randomly rough or regularly patterned features, also trap liquid in surface features, exhibiting an additional response that depends on liquid density alone. Combining smooth- and textured-surface resonators in a monolithic sensor enables simultaneous extraction of liquid density and viscosity.

We have demonstrated that a thickness shear mode quartz resonator can be used as a real-time, in situ monitor of the state-of-charge of lead-acid batteries. The resonator is sensitive to hanges in the density and viscosity of the sulfuric acid electrolyte. Both of these liquid parameters vary monotonically with the battery state-of-charge. This new monitor is more precise than sampling hydrometers, and since it is compatible with the Corrosive electrolyte environment, it can be used for in situ monitoring. A TSM resonator consists of gold electrodes deposited on opposite surfaces of a thin AT-cut quartz crystal. When an RF voltage is applied to the electrodes, a shear strain is introduced in the piezoelectric quartz and mechanical resonance occurs between the surfaces. A liquid in contact with one of the quartz surfaces is viscously entrained, which perturbs the resonant frequency and resonance magnitude. If the surface is smooth, the changes in both frequency and magnitude are proportional to ({rho}{eta}) {sup {1/2}}, where {rho} is the liquid density and {eta} is the viscosity.

Synthetic Aperture Radar (SAR) is used to form images that are maps of radar reflectivity of some scene of interest, from range soundings taken over some spatial aperture. Additionally, the range soundings are typically synthesized from a sampled frequency aperture. Efficient processing of the collected data necessitates using efficient digital signal processing techniques such as vector multiplies and fast implementations of the Discrete Fourier Transform. Inherent in image formation algorithms that use these is a trade-off between the size of the scene that can be acceptably imaged, and the resolution with which the image can be made. These limits arise from migration errors and spatially variant phase errors, and different algorithms mitigate these to varying degrees. Two fairly successful algorithms for airborne SARs are Polar Format processing, and Overlapped Subaperture (OSA) processing. This report introduces and summarizes the analysis of generalized Tiered Subaperture (TSA) techniques that are a superset of both Polar Format processing and OSA processing. It is shown how tiers of subapertures in both azimuth and range can effectively mitigate both migration errors and spatially variant phase errors to allow virtually arbitrary scene sizes, even in a dynamic motion environment.

A simple model has been developed to address a pragmatic question: What fraction of its research and development budget should a national laboratory devote to enhancing technology in the private sector? In dealing with lab-wide budgets in an aggregate sense, the model uses three parameters - fraction of lab R&D transferable to industry, transfer efficiency and payback to laboratory missions - to partition fixed R&D resources between technology transfer and core missions. It is a steady-state model in that the transfer process is assumed to work in equilibrium with technology generation. The results presented should be of use to those engaged in managing and overseeing federal laboratory technology transfer activities.

Military Specifications call out general procedures and guidelines for conducting contact resistance measurements on chemical conversion coated panels. This paper deals with a test procedure developed at Sandia National Laboratories used to conduct contact electrical resistance on non-chromated conversion coated test panels. MIL-C-81706 {open_quotes}Chemical Conversion Materials For Coating Aluminum and Aluminum Alloys{close_quotes} was the reference specification used for guidance.

The photodiode transition indicator is a device which has been successfully used to determine the onset of boundary layer transition on numerous hypersonic flight vehicles. The exact source of the electromagnetic radiation detected by the photodiode at transition was not understood. In some cases early saturation of the device occurred, and the device failed to detect transition. Analyses have been performed to determine the source of the radiation producing the photodiode signal. The results of these analyses indicate that the most likely source of the radiation is blackbody emission from the heatshield material bordering the quartz window of the device. Good agreement between flight data and calculations based on this radiation source has been obtained. Analyses also indicate that the most probable source of the radiation causing early saturation is blackbody radiation from carbon particles which break away from the nosetip during the ablation process.

Electrical discharges from a lightning simulator were directed at Mk12 aeroshells. Buckling of the aluminum substrate was observed after some 100-kA shots, and severe damage consisting of tearing of the aluminum and the production of inward flying aluminum shrapnel was observed after some 200-kA peak-current shots. Some shots resulted in severe damage to both the aluminum and the carbon-phenolic ablative material. It is reasonable to conclude from the experimental results that a lightning stroke with very high-peak current could, by itself, produce an opening in an Mk12 aeroshell. Because the aeroshell is part of the nuclear explosive safety exclusion region for the Mk12/W62 nuclear weapon, an opening would significantly reduce the assured safety of the weapon. It is unlikely that the observed interaction between lightning and the aeroshells would have been predicted by any form of computer simulation.

To draft a procurement specification for the Long-Reach Manipulator (LRM), the benefits and limitations of the various robotic control system architectures available need to be determined. This report identifies and describes the advantages and potential disadvantages of using an open control system versus a closed (or proprietary) system, focusing on integration of interfaces for sensors, end effectors, tooling, and operator interfaces. In addition, the various controls methodologies of several recent systems are described. Finally, the reasons behind the recommendation to procure an open control system are discussed.

The work for the development of an Annular Precision Linear Shaped Charge (APLSC) Flight Termination System (FTS) for the Operation and Deployment Experiment Simulator (ODES) program is discussed and presented in this report. The Precision Linear Shaped Charge (PLSC) concept was recently developed at Sandia. The APLSC component is designed to produce a copper jet to cut four inch diameter holes in each of two spherical tanks, one containing fuel and the other an oxidizer that are hyperbolic when mixed, to terminate the ODES vehicle flight if necessary. The FTS includes two detonators, six Mild Detonating Fuse (MDF) transfer lines, a detonator block, detonation transfer manifold, and the APLSC component. PLSCs have previously been designed in ring components where the jet penetrating axis is either directly away or toward the center of the ring assembly. Typically, these PLSC components are designed to cut metal cylinders from the outside inward or from the inside outward. The ODES program requires an annular linear shaped charge. The (Linear Shaped Charge Analysis) LESCA code was used to design this 65 grain/foot APLSC and data comparing the analytically predicted to experimental data are presented. Jet penetration data are presented to assess the maximum depth and reproducibility of the penetration. Data are presented for full scale tests, including all FTS components, and conducted with nominal 19 inch diameter, spherical tanks.

This report provides a statistical description of the types and severities of tractor semi-trailer accidents involving at least one fatality. The data were developed for use in risk assessments of hazardous materials transportation. Several accident databases were reviewed to determine their suitability to the task. The TIFA (Trucks Involved in Fatal Accidents) database created at the University of Michigan Transportation Research Institute was extensively utilized. Supplementary data on collision and fire severity, which was not available in the TIFA database, were obtained by reviewing police reports for selected TIFA accidents. The results are described in terms of frequencies of different accident types and cumulative distribution functions for the peak contact velocity, rollover skid distance, fire temperature, fire size, fire separation, and fire duration.