Publications

In developing secure applications and systems, the designers often must incorporate secure user identification in the design specification. In this paper, the authors study secure off line authenticated user identification schemes based on a biometric system that can measure a user`s biometric accurately (up to some Hamming distance). The schemes presented here enhance identification and authorization in secure applications by binding a biometric template with authorization information on a token such as a magnetic strip. Also developed here are schemes specifically designed to minimize the compromise of a user`s private biometrics data, encapsulated in the authorization information, without requiring secure hardware tokens. In this paper the authors furthermore study the feasibility of biometrics performing as an enabling technology for secure system and application design. The authors investigate a new technology which allows a user`s biometrics to facilitate cryptographic mechanisms.

This report summarizes work on the development of ultra-low power microwave CHFET integrated circuit development. Power consumption of microwave circuits has been reduced by factors of 50--1,000 over commercially available circuits. Positive threshold field effect transistors (nJFETs and PHEMTs) have been used to design and fabricate microwave circuits with power levels of 1 milliwatt or less. 0.7 {micro}m gate nJFETs are suitable for both digital CHFET integrated circuits as well as low power microwave circuits. Both hybrid amplifiers and MMICs were demonstrated at the 1 mW level at 2.4 GHz. Advanced devices were also developed and characterized for even lower power levels. Amplifiers with 0.3 {micro}m JFETs were simulated with 8--10 dB gain down to power levels of 250 microwatts ({mu}W). However 0.25 {micro}m PHEMTs proved superior to the JFETs with amplifier gain of 8 dB at 217 MHz and 50 {mu}W power levels but they are not integrable with the digital CHFET technology.

A compact, short pulse, repetitive accelerator has many useful military and commercial applications in biological counter proliferation, materials processing, radiography, and sterilization (medical instruments, waste, and food). The goal of this project was to develop and demonstrate a small, 700 kV accelerator, which can produce 7 kA particle beams with pulse lengths of 10--30 ns at rates up to 50 Hz. At reduced power levels, longer pulses or higher repetition rates (up to 10 kHz) could be achieved. Two switching technologies were tested: (1) spark gaps, which have been used to build low repetition rate accelerators for many years; and (2) high gain photoconductive semiconductor switches (PCSS), a new solid state switching technology. This plan was economical, because it used existing hardware for the accelerator, and the PCSS material and fabrication for one module was relatively inexpensive. It was research oriented, because it provided a test bed to examine the utility of other emerging switching technologies, such as magnetic switches. At full power, the accelerator will produce 700 kV and 7 kA with either the spark gap or PCSS pulser.

Sandia National Laboratories has a substantial effort in development of microelectromechanical system (MEMS) technologies. This miniaturization capability can lead to low-cost, small, high-performance systems-on-a-chip, and have many applications ranging from advanced military systems to large-volume commercial markets like automobiles, rf or land-based communications networks and equipment, or commercial electronics. One of the key challenges in realization of the microsystem is integration of several technologies including digital electronics; analog and rf electronics, optoelectronics, sensors and actuators, and advanced packaging technologies. In this work they describe efforts in integrating MEMS and optoelectronic or photonic functions and the fabrication constraints on both system components. the MEMS technology used in this work are silicon surface-machined systems fabricated using the SUMMiT (Sandia Ultraplanar Multilevel MEMS Technology) process developed at Sandia. This process includes chemical-mechanical polishing as an intermediate planarization step to allow the use of 4 or 5 levels of polysilicon.

An automated system for calibrating vacuum gauges over the pressure range of 10{sup {minus}6} to 0.1 Pa was designed and constructed at the National Institute of Standards and Technology (NIST) for the Department of Energy (DOE) Primary Standards Laboratory at Sandia National Laboratories (SNL). Calculable pressures are generated by passing a known flow of gas through an orifice of known conductance. The orifice conductance is derived from dimensional measurements and accurate flows are generated using metal capillary leaks. The expanded uncertainty (k = 2) in the generated pressure is estimated to be between 1% and 4% over the calibration range. The design, calibration results. and component uncertainties will be discussed.

Over the past several years, the US Nuclear Regulatory Commission (NRC) has sponsored the development of a new method for performing human reliability analyses (HRAs). A major impetus for the program was the recognized need for a method that would not only address errors of omission (EOOs), but also errors of commission (EOCs). Although several documents have been issued describing the basis and development of the new method referred to as ``A Technique for Human Event Analysis`` (ATHEANA), two documents were drafted to initially provide the necessary documentation for applying the method: the frame of reference (FOR) manual, which served as the technical basis document for the method and the implementation guideline (IG), which provided step by step guidance for applying the method. Upon the completion of the draft FOR manual and the draft IG in April 1997, along with several step-throughs of the process by the development team, the method was ready for a third-party test. The method was demonstrated at Seabrook Station in July 1997. The main goals of the demonstration were to (1) test the ATHENA process as described in the FOR manual and the IG, (2) test a training package developed for the method, (3) test the hypothesis that plant operators and trainers have significant insight into the EFCs that can make UAs more likely, and (4) identify ways to improve the method and its documentation. The results of the Seabrook demonstration are evaluated against the success criteria, and important findings and recommendations regarding ATHENA that were obtained from the demonstration are presented here.

Analysis of cost and performance of physical security systems can be a complex, multi-dimensional problem. There are a number of point tools that address various aspects of cost and performance analysis. Increased interest in cost tradeoffs of physical security alternatives has motivated development of an architecture called Cost and Performance Analysis (CPA), which takes a top-down approach to aligning cost and performance metrics. CPA incorporates results generated by existing physical security system performance analysis tools, and utilizes an existing cost analysis tool. The objective of this architecture is to offer comprehensive visualization of complex data to security analysts and decision-makers.

In most probabilistic risk assessments, there is a set of accident scenarios that involves the physical responses of a system to environmental challenges. Examples include the effects of earthquakes and fires on the operability of a nuclear reactor safety system, the effects of fires and impacts on the safety integrity of a nuclear weapon, and the effects of human intrusions on the transport of radionuclides from an underground waste facility. The physical responses of the system to these challenges can be quite complex, and their evaluation may require the use of detailed computer codes that are very time consuming to execute. Yet, to perform meaningful probabilistic analyses, it is necessary to evaluate the responses for a large number of variations in the input parameters that describe the initial state of the system, the environments to which it is exposed, and the effects of human interaction. Because the uncertainties of the system response may be very large, it may also be necessary to perform these evaluations for various values of modeling parameters that have high uncertainties, such as material stiffnesses, surface emissivities, and ground permeabilities. The authors have been exploring the use of artificial neural networks (ANNs) as a means for estimating the physical responses of complex systems to phenomenological events such as those cited above. These networks are designed as mathematical constructs with adjustable parameters that can be trained so that the results obtained from the networks will simulate the results obtained from the detailed computer codes. The intent is for the networks to provide an adequate simulation of the detailed codes over a significant range of variables while requiring only a small fraction of the computer processing time required by the detailed codes. This enables the authors to integrate the physical response analyses into the probabilistic models in order to estimate the probabilities of various responses.

GaN etching can be affected by a wide variety of parameters including plasma chemistry and plasma density. Chlorine-based plasmas have been the most widely used plasma chemistries to etch GaN due to the high volatility of the GaCl{sub 3} and NCl etch products. The source of Cl and the addition of secondary gases can dramatically influence the etch characteristics primarily due to their effect on the concentration of reactive Cl generated in the plasma. In addition, high-density plasma etch systems have yielded high quality etching of GaN due to plasma densities which are 2 to 4 orders of magnitude higher than reactive ion etch (RIE) plasma systems. The high plasma densities enhance the bond breaking efficiency of the GaN, the formation of volatile etch products, and the sputter desorption of the etch products from the surface. In this study, the authors report GaN etch results for a high-density inductively coupled plasma (ICP) as a function of BCl{sub 3}:Cl{sub 2} flow ratio, dc-bias, chamber-pressure, and ICP source power. GaN etch rates ranging from {approximately}100 {angstrom}/min to > 8,000 {angstrom}/min were obtained with smooth etch morphology and anisotropic profiles.

Enhanced tribological properties have been observed after treatment with pulsed high power ion beams, which results in rapid melting and resolidification of the surface. The authors have treated and tested 440C martensitic stainless steel (Fe-17 Cr-1 C). Ti and Al samples were sputter coated and ion beam treated to produce surface alloying. The samples were treated at the RHEPP-I facility at Sandia National Laboratories (0.5 MV, 0.5--1 {micro}s at sample location, <10 J/cm{sup 2}, 1--5 {micro}m ion range). They have observed a reduction in size of second phase particles and other microstructural changes in 440C steel. The hardness of treated 440C increases with ion beam fluence and a maximum hardness increase of a factor of 5 is obtained. Low wear rates are observed in wear tested of treated 440C steel. Surface alloyed Ti-Pt layers show improvements in hardness up to a factor of 3 over untreated Ti, and surface alloys of Al-Si result in a hardness increase of a factor of two over untreated Al. Both surface alloys show increased durability in wear testing. Rutherford Backscattering (RBS) measurements show overlayer mixing to the depth of the melted layer. X-ray Diffraction (XRD) and TEM confirm the existence of metastable states within the treated layer. Treated layer depths have been measured from 1--10 {micro}m.

The mission of the national laboratories has changed from weapon design and production to stockpile maintenance. Design engineers are becoming few in number and years worth of experience is about to be lost. What will happen when new weapons are designed or retrofits need to be made? Who will know the lessons learned in the past? What process will be followed? When and what software codes should be used? Intelligent design is the answer to the questions posed above for weapon design; for any design. An interactive design development environment will allow the designers of the future access to the knowledge of yesterday, today and tomorrow. Design guides, rules of thumb, lessons learned, production capabilities, production data, process flow, and analysis codes will be included in intelligent design. An intelligent design environment is being developed as a heuristic, knowledge based system and as a diagnostic design tool. The system provides the framework for incorporating rules of thumb from experienced design engineers, available manufacturing processes, including the newest ones, and manufacturing databases, with current data, to help reduce design margins. The system also has the capability to access analysis and legacy codes appropriately. A modular framework allows for various portions to be added or deleted based on the application. This paper presents the driving forces for developing an intelligent design environment and an overview of the system. This overview will include the system architecture and how it relates to the capture and utilization of design and manufacturing knowledge. The paper concludes with a discussion of realized and expected benefits.

The detection and refocus of moving targets in SAR imagery is of interest in a number of applications. In this paper the authors address the problem of refocusing a blurred signature that has by some means been identified as a moving target. They assume that the target vehicle velocity is constant, i.e., the motion is in a straight line with constant speed. The refocus is accomplished by application of a two-dimensional phase function to the phase history data obtained via Fourier transformation of an image chip that contains the blurred moving target data. By considering separately the phase effects of the range and cross-range components of the target velocity vector, they show how the appropriate phase correction term can be derived as a two-parameter function. They then show a procedure for estimating the two parameters, so that the blurred signature can be automatically refocused. The algorithm utilizes optimization of an image domain contrast metric. They present results of refocusing moving targets in real SAR imagery by this method.

Sandia National Laboratories has conducted research in chemical sensing and analysis of explosives for many years. Recently, that experience has been directed towards detecting mines and unexploded ordnance (UXO) by sensing the low-level explosive signatures associated with these objects. The authors focus has been on the classification of UXO in shallow water and anti-personnel/anti tank mines on land. The objective of this work is to develop a field portable chemical sensing system which can be used to examine mine-like objects (MLO) to determine whether there are explosive molecules associated with the MLO. Two sampling subsystems have been designed, one for water collection and one for soil/vapor sampling. The water sampler utilizes a flow-through chemical adsorbent canister to extract and concentrate the explosive molecules. Explosive molecules are thermally desorbed from the concentrator and trapped in a focusing stage for rapid desorption into an ion-mobility spectrometer (IMS). The authors describe a prototype system which consists of a sampler, concentrator-focuser, and detector. The soil sampler employs a light-weight probe for extracting and concentrating explosive vapor from the soil in the vicinity of an MLO. The chemical sensing system is capable of sub-part-per-billion detection of TNT and related explosive munition compounds. They present the results of field and laboratory tests on buried landmines which demonstrate their ability to detect the explosive signatures associated with these objects.

The disposition of the large backlog of plutonium residues at the Rocky Flats Environmental Technology Site (Rocky Flats) will require interim storage and subsequent shipment to a waste repository. Current plans call for disposal at the Waste Isolation Pilot Plant (WIPP) and the transportation to WIPP in the TRUPACT-II. The transportation phase will require the residues to be packaged in a container that is more robust than a standard 55 gallon waste drum. Rocky Flats has designed the Pipe Overpack Container to meet this need. The potential for damage to this container during onsite storage in unhardened structures for several hypothetical accident scenarios has been addressed using finite element calculations. This report will describe the initial conditions and assumptions for these analyses and the predicted response of the container.

This paper describes a novel digital signal processing algorithm for adaptively detecting and identifying signals buried in noise. The algorithm continually computes and updates the long-term statistics and spectral characteristics of the background noise. Using this noise model, a set of adaptive thresholds and matched digital filters are implemented to enhance and detect signals that are buried in the noise. The algorithm furthermore automatically suppresses coherent noise sources and adapts to time-varying signal conditions. Signal detection is performed in both the time-domain and the frequency-domain, thereby permitting the detection of both broad-band transients and narrow-band signals. The detection algorithm also provides for the computation of important signal features such as amplitude, timing, and phase information. Signal identification is achieved through a combination of frequency-domain template matching and spectral peak picking. The algorithm described herein is well suited for real-time implementation on digital signal processing hardware. This paper presents the theory of the adaptive algorithm, provides an algorithmic block diagram, and demonstrate its implementation and performance with real-world data. The computational efficiency of the algorithm is demonstrated through benchmarks on specific DSP hardware. The applications for this algorithm, which range from vibration analysis to real-time image processing, are also discussed.

It has been recognized that nondestructive inspection (NDI) techniques and instruments that have proven themselves in the laboratory do not always perform as well under field conditions. In this paper the authors explore combinations of formal laboratory and field experimentation to characterize NDI processes as they may be implemented in field conditions. They also discuss appropriate modeling for probability of detection (POD) curves as applied to data gathered under field conditions. A case is made for expanding the more traditional two-parameter models to models using either three or four parameters. They use NDI data gathered from various airframe inspection programs to illustrate the points.

Si{sup +} implant activation efficiencies above 90%, even at doses of 5 {times} 10{sup 15} cm{sup {minus}2}, have been achieved in GaN by RTP at 1,400--1,500 C for 10 secs. The annealing system utilizes with MoSi{sub 2} heating elements capable of operation up to 1,900 C, producing high heating and cooling rates (up to 100 C{center_dot}s{sup {minus}1}). Unencapsulated GaN show severe surface pitting at 1,300 C, and complete loss of the film by evaporation at 1,400 C. Dissociation of nitrogen from the surface is found to occur with an approximate activation energy of 3.8 eV for GaN (compared to 4.4 eV for AlN and 3.4 eV for InN). Encapsulation with either rf-magnetron reactively sputtered or MOMBE-grown AlN thin films provide protection against GaN surface degradation up to 1,400 C, where peak electron concentrations of {approximately} 5 {times} 10{sup 20} cm{sup {minus}3} can be achieved in Si-implanted GaN. SIMS profiling showed little measurable redistribution of Si, suggesting D{sub Si} {le} 10{sup {minus}13} cm{sup 2}{center_dot}s{sup {minus}1} at 1,400 C . The implant activation efficiency decreases at higher temperatures, which may result from Si{sub Ga} to Si{sub N} site switching and resultant self-compensation.

In this paper the authors give a construction of wavelets which are (a) semi-orthogonal with respect to an arbitrary elliptic bilinear form a({center_dot},{center_dot}) on the Sobolev space H{sub 0}{sup 1}((0, L)) and (b) continuous and piecewise linear on an arbitrary partition of [0, L]. They illustrate this construction using a model problem. They also construct alpha-orthogonal Battle-Lemarie type wavelets which fully diagonalize the Galerkin discretized matrix for the model problem with domain IR. Finally they describe a hybrid basis consisting of a combination of elements from the semi-orthogonal wavelet basis and the hierarchical Schauder basis. Numerical experiments indicate that this basis leads to robust scalable Galerkin discretizations of the model problem which remain well-conditioned independent of {epsilon}, L, and the refinement level K.

Investment casting is an important method for fabricating a variety of high quality components in mechanical systems. Cast components, unfortunately, have a large design and gate/runner build time associated with their fabrication. In addition, casting engineers often require many years of actual experience in order to consistently pour high quality castings. Since 1989, Sandia National Laboratories has been investigating casting technology and software that will reduce the time overhead involved in producing quality casts. Several companies in the casting industry have teamed up with Sandia to form the FASTCAST Consortium. One result of this research and the formation of the FASTCAST consortium is the creation of the WinMod software, an expert casting advisor that supports the decision making process of the casting engineer through visualization and advice to help eliminate possible casting defects.

The effect of temperature on the reversible and irreversible capacities of disordered carbons derived from polymethacryonitrile (PMAN) and divinylbenzene (DVB) copolymers was studied in 1 M LiPF{sub 6}/ethylene carbonate (EC)-dimethyl carbonate (DMC) (1:1 v/v) solution by galvanostatic cycling. The kinetics of passive film formation were examined by complex-impedance spectroscopy. Temperatures of 5, 21, and 35 C were used in the study.

Electrical characteristics of hybrid power sources consisting of Li-ion cells and double layer capacitors were studied at 25 C and {minus}20 C. The cells were initially evaluated for pulse performance and then measured in hybrid modes of operation. Cells manufactured by Panasonic delivered pulses up to 3A and cells from A and T delivered 4A at 25 C before cell capacity dropped. Measured cell resistances were 0.15 ohms and 0.12 ohms, respectively. These measurements were repeated at {minus}20 C. Direct coupling of the cells and capacitors (dumb hybrid) extended the pulse limits to 5.6A using the Panasonic cells and 9A for the A and T cells. Operation in a smart hybrid mode using uncoupled cell/capacitor discharge allowed full cell capacity usage at 25 C and showed a factor of 5 improvement in delivered capacity at {minus}20 C.

The power requirements for an inverter application were specified to be 500 V at 360 A, or 180 kW per each of six 1-s pulses delivered over a period of 10 minutes. Conventional high-power sources (e.g., flywheels) could not meet these requirements and the use of a thermal battery was considered. The final design involved four, 125-cell, 50-kW modules connected in series. A module using the LiSi/CoS{sub 2} couple and all-Li (LiCI-LiBr-LiF minimum-melting) electrolyte was successfully developed and tested. A power level of over 40 kW was delivered during a 0.5-s pulse. This translates into a specific power level of over 9 kW/kg or 19.2 kW/L delivered from a module. The module was still able to deliver over 30 kW during a 1-s pulse after 10 minutes.

The ignition processes that take place during activation of a 16 cell, center hole fired thermal battery were examined by monitoring the voltage of each cell during activation. The average rise time of each cell to a voltage of 1.125 V was determined for the LiSi/LiCl-LiBr-LiF/FeS{sub 2} electrochemical system. The effects of heat pellet composition, center hole diameter, and the load on the activation parameters were examined for three different igniters. A large variability in individual cell performance was evident along with cell reversal, depending on the location of the cell in the stack. It was not possible to draw detailed statistical information of the relative ignition sequence due to the intrinsic large scatter in the data.

This paper reviews issues related to the use of aeroelastic tailoring as a cost-effective, passive means to shape the power curve and reduce loads. Wind turbine blades bend and twist during operation, effectively altering the angle of attack, which in turn affects loads and energy production. There are blades now in use that have significant aeroelastic couplings, either on purpose or because of flexible and light-weight designs. Since aeroelastic effects are almost unavoidable in flexible blade designs, it may be desirable to tailor these effects to the authors advantage. Efforts have been directed at adding flexible devices to a blade, or blade tip, to passively regulate power (or speed) in high winds. It is also possible to build a small amount of desirable twisting into the load response of a blade with proper asymmetric fiber lay up in the blade skin. (Such coupling is akin to distributed {delta}{sub 3} without mechanical hinges.) The tailored twisting can create an aeroelastic effect that has payoff in either better power production or in vibration alleviation, or both. Several research efforts have addressed different parts of this issue. Research and development in the use of aeroelastic tailoring on helicopter rotors is reviewed. Potential energy gains as a function of twist coupling are reviewed. The effects of such coupling on rotor stability have been studied and are presented here. The ability to design in twist coupling with either stretching or bending loads is examined also.

This report describes the numerical procedure used to implement the Green`s function method for solving the Poisson equation in two-dimensional (r,z) cylindrical coordinates. The procedure can determine the solution to a problem with any or all of the applied voltage boundary conditions, dielectric media, floating (insulated) conducting media, dielectric surface charging, and volumetric space charge. The numerical solution is reasonably fast, and the dimension of the linear problem to be solved is that of the number of elements needed to represent the surfaces, not the whole computational volume. The method of solution is useful in the simulation of plasma particle motion in the vicinity of complex surface structures as found in microelectronics plasma processing applications. This report is a stand-alone supplement to the previous Sandia Technical Report SAND98-0537 presenting the two-dimensional Cartesian Poisson solver.

The need for a reliable, fast, wireless telemetry system in the drilling industry is great but the technical challenge to develop such a system is huge. A downhole wireless telemetry system based on Surface Area Modulation (SAM) has been developed which involves the introduction of an electrically insulated gap near the bottom of an otherwise conductive drillstring. The electrical resistance of this gap can be modulated to alter the electrical characteristics of a circuit involving a surface power supply, the sections of the drillstring above and below the gap, the earth, and a nearby return electrode. These changes alter the current in the circuit, which can be monitored at the surface with an ammeter. Downhole data are encoded and transmitted to the surface as a pattern of current oscillations. In a field test, the SAM system successfully transmitted downhole information from depths of 1,400 ft below the fluid level to the surface at a rate of 110 baud. Electrical insulation on the outside of the simulated drillstring was required to achieve this level of performance. Electrically insulated tubing improved the data transmission rate at a given depth by more than an order of magnitude, and increased the maximum depth from which successful data telemetry could be achieved by more than a factor of two.

This study examines ergonomic stressors associated with front-end process tool maintenance, relates them to decreased machine utilization, and proposes solution strategies to reduce their negative impact on productivity. Member company ergonomists observed technicians performing field maintenance tasks on seven different bottleneck tools and recorded ergonomic stressors using SEMaCheck, a graphics-based, integrated checklist developed by Sandia National Laboratories. The top ten stressors were prioritized according to a cost formula that accounted for difficulty, time, and potential errors. Estimates of additional time on a task caused by ergonomic stressors demonstrated that machine utilization could be increased from 6% to 25%. Optimal solution strategies were formulated based on redesign budget, stressor cost, and estimates of solution costs and benefits

The concept of ``progressive Lattice Sampling`` as a basis for generating successive finite element response surfaces that are increasingly effective in matching actual response functions is investigated here. The goal is optimal response surface generation, which achieves an adequate representation of system behavior over the relevant parameter space of a problem with a minimum of computational and user effort. Such is important in global optimization and in estimation of system probabilistic response, which are both made much more viable by replacing large complex computer models of system behavior by fast running accurate approximations. This paper outlines the methodology for Finite Element/Lattice Sampling (FE/LS) response surface generation and examines the effectiveness of progressively refined FE/LS response surfaces in decoupled Monte Carlo analysis of several model problems. The proposed method is in all cases more efficient (generally orders of magnitude more efficient) than direct Monte Carlo evaluation, with no appreciable loss of accuracy. Thus, when arriving at probabilities or distributions by Monte Carlo, it appears to be more efficient to expend computer model function evaluations on building a FE/LS response surface than to expend them in direct Monte Carlo sampling. Furthermore, the marginal efficiency of the FE/LS decoupled Monte Carlo approach increases as the size of the computer model increases, which is a very favorable property.

This report represents the completion of a three-year Laboratory-Directed Research and Development (LDRD) program to investigate sub-wavelength surface relief structures fabricated by direct-write e-beam technology as unique and very high-efficiency optical elements. A semiconductor layer with sub-wavelength sized etched openings or features can be considered as a layer with an effective index of refraction determined by the fraction of the surface filled with semiconductor relative to the fraction filled with air or other material. Such as a layer can be used to implement planar gradient-index lenses on a surface. Additionally, the nanometer-scale surface structures have diffractive properties that allow the direct manipulation of polarization and altering of the reflective properties of surfaces. With this technology a single direct-write mask and etch can be used to integrate a wide variety of optical functions into a device surface with high efficiencies; allowing for example, direct integration of polarizing optics into the surface with high efficiencies; allowing for example, direct integration of polarizing optics into the surfaces of devices, forming anti-reflection surfaces or fabricating high-efficiency, high-numerical aperture lenses, including integration inside vertical semiconductor laser cavities.

This report summarizes work on the development of high-speed vertical cavity surface emitting lasers (VCSELs) for multi-gigabit per second optical data communications applications (LDRD case number 3506.010). The program resulted in VCSELs that operate with an electrical bandwidth of 20 GHz along with a simultaneous conversion efficiency (DC to light) of about 20%. To achieve the large electrical bandwidth, conventional VCSELs were appropriately modified to reduce electrical parasitics and adapted for microwave probing for high-speed operation.

Micromachining technologies, or Micro-Electro-Mechanical Systems (MEMS), enable the develop of low-cost devices capable of sensing motion in a reliable and accurate manner. Sandia has developed a MEMS fabrication process for integrating both the micromechanical structures and microelectronics circuitry of surface micromachined sensors, such as silicon accelerometers, on the same chip. Integration of the micromechanical sensor elements with microelectronics provides substantial performance and reliability advantages for MEMS accelerometers. A design team at Sandia was assembled to develop a micromachined silicon accelerometer capable of surviving and measuring very high accelerations (up to 50,000 times the acceleration due to gravity). The Sandia integrated surface micromachining process was selected for fabrication of the sensor due to the extreme measurement sensitivity potential associated with integrated microelectronics. Very fine measurement sensitivity was required due to the very small accelerometer proof mass (< 200 {times} 10{sup {minus}9} gram) obtainable with this surface micromachining process. The small proof mass corresponded to small sensor deflections which required very sensitive electronics to enable accurate acceleration measurement over a range of 1,000 to 50,000 times the acceleration due to gravity. Several prototype sensors, based on a suspended plate mass configuration, were developed and the details of the design, modeling, fabrication and validation of the device will be presented in this paper. The device was analyzed using both conventional lumped parameter modeling techniques and finite element analysis tools. The device was tested and performed well over its design range (the device was tested over a range of a few thousand G to 46,000 G, where 1 G equals the acceleration due to gravity).

The intent and purpose of this work was to investigate and demonstrate cooperative behavior among a group of mobile robot machines. The specific goal of this work was to build a small swarm of identical machines and control them in such a way as to show a coordinated movement of the group in a flocking manner, similar to that observed in nature. Control of the swarm`s individual members and its overall configuration is available to the human user via a graphic man-machine interface running on a base station control computer. Any robot may be designated as the nominal leader through the interface tool, which then may be commanded to proceed to a particular geographic destination. The remainder of the flock follows the leader by maintaining their relative positions in formation, as specified by the human controller through the interface. The formation`s configuration can be altered manually through an interactive graphic-based tool. An alternative mode of control allows for teleoperation of one robot, with the flock following along as described above.

An autonomous mobile robotic capability is critical to developing remote work applications for hazardous environments. A few potential applications include humanitarian demining and ordnance neutralization, extraterrestrial science exploration, and hazardous waste cleanup. The ability of the remote platform to sense and maneuver within its environment is a basic technology requirement which is currently lacking. This enabling technology will open the door for force multiplication and cost effective solutions to remote operations. The ultimate goal of this work is to develop a mobile robotic platform that can identify and avoid local obstacles as it traverses from its current location to a specified destination. This goal directed autonomous navigation scheme uses the Global Positioning System (GPS) to identify the robot`s current coordinates in space and neural network processing of LADAR range images for local obstacle detection and avoidance. The initial year funding provided by this LDRD project has developed a small exterior mobile robotic development platform and a fieldable version of Sandia`s Scannerless Range Imager (SRI) system. The robotic testbed platform is based on the Surveillance And Reconnaissance ground Equipment (SARGE) robotic vehicle design recently developed for the US DoD. Contingent upon follow-on funding, future enhancements will develop neural network processing of the range map data to traverse unstructured exterior terrain while avoiding obstacles. The SRI will provide real-time range images to a neural network for autonomous guidance. Neural network processing of the range map data will allow real-time operation on a Pentium based embedded processor board.

The report is intended to address the need for data analysis in environmental sampling programs. Routine environmental sampling has been conducted at Sandia National Laboratories/New Mexico (SNL/NM) to ensure that site operations have not resulted in undue risk to the public and the environment. Over the years, large amounts of data have been accumulated. The richness of the data should be fully utilized to improve sampling design and prioritize sampling needs for a technically-sound, yet cost-effective sampling design. The report presents a methodology for analyzing environmental monitoring data and demonstrates the application by using SNL`s historical monitoring data. Recommendations for sampling design modification were derived based on the results of the analyses.

LUG and Sway brace ANalysis (LUGSAN) II is an analysis and database computer program that is designed to calculate store lug and sway brace loads for aircraft captive carriage. LUGSAN II combines the rigid body dynamics code, SWAY85, with a Macintosh Hypercard database to function both as an analysis and archival system. This report describes the LUGSAN II application program, which operates on the Macintosh System (Hypercard 2.2 or later) and includes function descriptions, layout examples, and sample sessions. Although this report is primarily a user`s manual, a brief overview of the LUGSAN II computer code is included with suggested resources for programmers.

Lost circulation, which is the loss of well drilling fluids to the formation while drilling, is a common problem encountered while drilling geothermal wells. The rapid detection of the loss of well drilling fluids is critical to the successful and cost-effective treatment of the wellbore to stop or minimize lost circulation. Sandia National Laboratories has developed an instrument to accurately measure the outflow rate of drilling fluids while drilling. This instrument, the Rolling Float Meter, has been under development at Sandia since 1991 and is now available for utilization by interested industry users. This report documents recent Rolling Float Meter design upgrades resulting from field testing and industry input, the effects of ongoing testing and evaluation both in the laboratory and in the field, and the final design package that is available to transfer this technology to industry users.

Two Monte Carlo programs, XITRAN and XMTRAN, were developed for calculating the emission of electrons from high-Z foils irradiated with x rays. XITRAN follows all individual elastic collisions of electrons with atoms, whereas XMTRAN uses the condensed-random-walk model. Both codes take into account photo-electrons, fluorescence radiation, and Auger electrons. Comparisons are made with an experiment by Dolan at Sandia Laboratories involving the backward and forward emission of electrons from a tantalum foil irradiated by 100-kV and 50-kV x-ray beams. There is good agreement between results from the XITRAN and XMTRAN codes. There emitted per incident x-ray photon, and in regard to the angular distribution of the emerging electrons. In regard to the electron energy spectra, there is fair agreement down to a spectral energy of 20 keV, whereas below 20 keV the calculated spectra lie considerably below the measurements.

This report is a user`s manual for GRAFLAB, which is a new database, analysis, and plotting package that has been written entirely in the MATLAB programming language. GRAFLAB is currently used for data reduction, analysis, and archival. GRAFLAB was written to replace GRAFAID, which is a FORTRAN database, analysis, and plotting package that runs on VAX/VMS.

In the present study we describe the development of an experimental fracture material property test method specific to dynamic fragmentation. Spherical test samples of the metals of interest are subjected to controlled impulsive stress loads by acceleration to high velocities with a light-gas launcher facility and subsequent normal impact on thin plates. Motion, deformation and fragmentation of the test samples are diagnosed with multiple flash radiography methods. The impact plate materials are selected to be transparent to the x-ray method so that only test metal material is imaged. Through a systematic series of such tests both strain-to-failure and fragmentation resistance properties are determined through this experimental method. Fragmentation property data for several steels, copper, aluminum, tantalum and titanium have been obtained to date. Aspects of the dynamic data have been analyzed with computational methods to achieve a better understanding of the processes leading to failure and fragmentation, and to test an existing computational fragmentation model.

Sandia has established a foundational technology in photonic integrated circuits (PICs) based on the (Al,Ga,In)As material system for optical communication, radar control and testing, and network switching applications at the important 1.3{mu}m/1.55{mu}m wavelengths. We investigated the optical, electrooptical, and microwave performance characteristics of the fundamental building-block PIC elements designed to be as simple and process-tolerant as possible, with particular emphasis placed on reducing optical insertion loss. Relatively conventional device array and circuit designs were built using these PIC elements: (1) to establish a baseline performance standard; (2) to assess the impact of epitaxial growth accuracy and uniformity, and of fabrication uniformity and yield; (3) to validate our theoretical and numerical models; and (4) to resolve the optical and microwave packaging issues associated with building fully packaged prototypes. Novel and more complex PIC designs and fabrication processes, viewed as higher payoff but higher risk, were explored in a parallel effort with the intention of meshing those advances into our baseline higher-yield capability as they mature. The application focus targeted the design and fabrication of packaged solitary modulators meeting the requirements of future wideband and high-speed analog and digital data links. Successfully prototyped devices are expected to feed into more complex PICs solving specific problems in high-performance communications, such as optical beamforming networks for phased array antennas.

The Waste Isolation Pilot Plant (WIPP) is being developed by the US Department of Energy for the geologic (deep underground) disposal of transuranic (TRU) waste. A Compliance Certification Application (CCA) of the WIPP (1) for such disposal was submitted to the US Environmental Protection Agency (EPA) in October, 1996, and is currently under review, with a decision anticipated in late 1997. An important component of the CCA is a performance assessment (PA) for the WIPP carried out by Sandia National Laboratories. The final outcome of the PA is a complementary cumulative distribution function (CCDF) for radionuclide releases from the WIPP to the accessible environment and an assessment of the confidence with which this CCDF can be estimated. This paper describes the computational process used to develop the CCDF. The results of uncertainty and sensitivity analysis are also presented.

The objective of the USNRC supported Lower Head Failure (LHF) Experiment Program at Sandia National Laboratories is to experimentally investigate and characterize the failure of the reactor pressure vessel (RPV) lower head due to the thermal and pressure loads of a severe accident. The experimental program is complemented by a modeling program focused on the development of a constitutive formulation for use in standard finite element structure mechanics codes. The problem is of importance because: lower head failure defines the initial conditions of all ex-vessel events; the inability of state-of-the-art models to simulate the result of the TMI-II accident (Stickler, et al. 1993); and TMI-II results suggest the possibility of in-vessel cooling, and creep deformation may be a precursor to water ingression leading to in-vessel cooling.

This paper presents an overview of several emerging nondestructive evaluation technologies that are being employed or considered for use to inspect commercial transport, commuter aircraft and military aircraft. An overview of the Federal Aviation Administration (FAA) Airworthiness Assurance NDI Validation Center (AANC) is described and how AANC teams with industry, universities, and other federal entities to assess these technologies.

Optimal response surface construction is being investigated as part of Sandia discretionary (LDRD) research into Analytic Nondeterministic Methods. The goal is to achieve an adequate representation of system behavior over the relevant parameter space of a problem with a minimum of computational and user effort. This is important in global optimization and in estimation of system probabilistic response, which are both made more viable by replacing large complex computer models with fast-running accurate and noiseless approximations. A Finite Element/Lattice Sampling (FE/LS) methodology for constructing progressively refined finite element response surfaces that reuse previous generations of samples is described here. Similar finite element implementations can be extended to N-dimensional problems and/or random fields and applied to other types of structured sampling paradigms, such as classical experimental design and Gauss, Lobatto, and Patterson sampling. Here the FE/LS model is applied in a ``decoupled`` Monte Carlo analysis of two sets of probability quantification test problems. The analytic test problems, spanning a large range of probabilities and very demanding failure region geometries, constitute a good testbed for comparing the performance of various nondeterministic analysis methods. In results here, FE/LS decoupled Monte Carlo analysis required orders of magnitude less computer time than direct Monte Carlo analysis, with no appreciable loss of accuracy. Thus, when arriving at probabilities or distributions by Monte Carlo, it appears to be more efficient to expend computer-model function evaluations on building a FE/LS response surface than to expend them in direct Monte Carlo sampling.

The single-event upset (SEU) responses of 16 Kbit to 1 Mbit SRAMs irradiated with low and high-energy heavy ions are reported. Standard low-energy heavy ion tests appear to be sufficiently conservative for technologies down to 0.5 {micro}m.

This paper presents preliminary analysis of a volcanic tuff repository containing a combination of low enrichment commercial spent nuclear fuels (SNF) and DOE-owned SNF packages. These SNFs were analyzed with respect to their criticality risks. Disposal of SNF packages containing significant fissile mass within a geologic repository must comply with current regulations relative to criticality safety during transportation and handling within operational facilities. However, once the repository is closed, the double contingency credits for criticality safety are subject to unremediable degradation, (e.g., water intrusion, continued presence of neutron absorbers in proximity to fissile material, and fissile material reconfiguration). The work presented in this paper focused on two attributes of criticality in a volcanic tuff repository for near-field and far-field scenarios: (1) scenario conditions necessary to have a criticality, and (2) consequences of a nuclear excursion that are components of risk. All criticality consequences are dependent upon eventual water intrusion into the repository and subsequent breach of the disposal package. Key criticality parameters necessary for a critical assembly are: (1) adequate thermal fissile mass, (2) adequate concentration of fissile material, (3) separation of neutron poison from fissile materials, and (4) sufficient neutron moderation (expressed in units of moderator to fissile atom ratios). Key results from this study indicated that the total energies released during a single excursion are minimal (comparable to those released in previous solution accidents), and the maximum frequency of occurrence is bounded by the saturation and temperature recycle times, thus resulting in small criticality risks.

This report represents the completion of a two years Laboratory Directed Research and Development (LDRD) program to investigate miniaturized systems for chemical detection and analysis. The future of advanced chemical detection and analysis is in miniature devices that are able to characterize increasingly complex samples, a laboratory on a chip. In this concept, chemical operations used to analyze complicated samples in a chemical laboratory sample handling, species separation, chemical derivitization and detection are incorporated into a miniature device. By using electrokinetic flow, this approach does not require pumps or valves, as fluids in microfabricated channels can be driven by externally applied voltages. This is ideal for sample handling in miniature devices. This project was to develop truly miniature on-chip optical systems based on Vertical Cavity Surface Emitting Lasers (VCSELs) and diffractive optics. These can be built into a complete system that also has on-chip electrokinetic fluid handling and chemical separation in a microfabricated column. The primary goal was the design and fabrication of an on-chip separation column with fluorescence sources and detectors that, using electrokinetic flow, can be used as the basis of an automated chemical analysis system. Secondary goals involved investigation of a dispersed fluorescence module that can be used to extend the versatility of the basic system and on chip, intracavity laser absorption as a high sensitivity detection technique.

Sandia National Laboratories is responsible for assuring that the US nuclear deterrent remains credible and that the one in a billion disaster of unintended nuclear detonation never occurs. Letting mistake-generated defects into the stockpile would undermine its mission. The current era of shrinking stockpiles is shrinking Sandia`s opportunities to discover and correct mistakes and fine tune processes over long production runs. In response, Sandia has chosen to develop and use a science-based, life cycle systems engineering practices that, in part, require understanding the design to manufacturing issues in enough detail to tune processes and eliminate mistakes before ever making a part. Defect prevention is a key area of concern that currently lacks sufficient theoretical understanding. This report is the result of a scoping study in the application of best-practice quality techniques that could address Sandia`s stockpile mission. The study provides detail on sources and control of mistakes, poka-yoke or mistake-proofing techniques, the Toyota Production system, and design theory in relation to manufacturing quality prediction. Scoping experiments are described and areas for future research are identified.

This report describes the numerical procedure used to implement the Green`s function method for solving the Poisson equation in two-dimensional Cartesian coordinates. The procedure can determine the solution to a problem with any or all of applied voltage boundary conditions, dielectric media, floating (insulated) conducting media, dielectric surface charging, periodic (reflective) boundary conditions, and volumetric space charge. The numerical solution is reasonably fast, and the dimension of the linear problem to be solved is that of the number of elements needed to represent the surfaces, not the whole computational volume. The method of solution is useful in the simulation of plasma particle motion in the vicinity of complex surface structures as found in microelectronics plasma processing applications. A FORTRAN implementation of this procedure is available from the author.

This paper presents a model for evaluating microcrack development and dilatant behavior of crystalline rocks. The model is developed within the concepts of continuum mechanics, with special emphasis on the development of internal boundaries in the continuum by utilizing fracture mechanics based cohesive zone models. The model is capable of describing the evolution from initial debonding through complete separation and subsequent void growth of an interface. An example problem of a rock salt specimen subjected to a high deviatoric load and low confinement is presented that predicts preferential opening of fractures oriented parallel with the maximum compressive stress axis.

Vapor phase transport in porous media is important in a number of environmental and industrial processes: soil moisture transport, vapor phase transport in the vadose zone, transport in the vicinity of buried nuclear waste, and industrial processes such as drying. The diffusion of water vapor in a packed bed containing residual liquid is examined experimentally. The objective is to quantify the effect of enhanced vapor diffusion resulting from evaporation/condensation in porous media subjected to a temperature gradient. Isothermal diffusion experiments in free-space were conducted to qualify the experimental apparatus and techniques. For these experiments measured diffusion coefficients are within 3.6% of those reported in the literature for the temperature range from 25 C to 40 C. Isothermal experiments in packed beds of glass beads were used to determine the tortuosity coefficient resulting in {tau} = 0.78 {+-} 0.028, which is also consistent with previously reported results. Nonisothermal experiments in packed beds in which condensation occurs were conducted to examine enhanced vapor diffusion. The interpretation of the results for these experiments is complicated by a gradual, but continuous, build-up of condensate in the packed beds during the course of the experiment. Results indicate diffusion coefficients which increase as a function of saturation resulting in enhancement of the vapor-phase transport by a factor of approximately four compared to a dry porous medium.

This project visualizes characterization data in a 3D setting, in real time. Real time in this sense means collecting the data and presenting it before it delays the user, and processing faster than the acquisition systems so no bottlenecks occur. The goals have been to build a volumetric viewer to display 3D data, demonstrate projecting other data, such as images, onto the 3D data, and display both the 3D and projected images as fast as the data became available. The authors have examined several ways to display 3D surface data. The most effective was generating polygonal surface meshes. They have created surface maps form a continuous stream of 3D range data, fused image data onto the geometry, and displayed the data with a standard 3D rendering package. In parallel with this, they have developed a method to project real-time images onto the surface created. A key component is mapping the data on the correct surfaces, which requires a-priori positional information along with accurate calibration of the camera and lens system.

SrBi{sub 2}Ta{sub 2}O{sub 9} (SBT) films have received considerable attention for use as non-volatile memory elements. The authors have developed a process to prepare SBT films with good ferroelectric properties at low temperatures. In this paper, they will present strategies used to optimize the properties of the films including film composition, the nature of the substrate (or bottom electrode) used, and the thermal processing cycle. Under appropriate conditions, {approximately} 1,700 {angstrom} films can be prepared which have a large switchable polarization (2P{sub r} > 10{micro}C/cm{sup 2}), and an operating voltage {le} 2.0 V.

This paper provides information on three (3) topics related to temperature measurements in an annealing procedure: (1) results of a series of experiments performed by CNIITMASH of the Russian consortium MOHT on their reactor pressure vessel (RPV) temperature measurement probe, (2) a discussion regarding uncertainties and errors in RPV temperature measurements, and (3) predictions from a thermal model of a spherical RPV temperature measurement probe. MOHT teamed with MPR Associates and was to perform the Annealing Demonstration Project (ADP) on behalf of the US Department of Energy, ESEERCo, EPRI, CRIEPI, Framatome, and Consumers Power Co. at the Midland plant. Experimental results show that the CNIITMASH probe errors are a maximum of about 27 C (49 F) during a 15 C/hr (27 F/hr) heat-up but only about 3 C (5.4 F) (0.6%) during the hold portion at 470 C (878 F). These errors are much smaller than those obtained from a similar series of experiments performed by Sandia National Laboratories (Sandia). The discussion about uncertainties and errors shows that results presented as a temperature difference provides a measure of the probe error. Qualitative agreement is shown between the model predictions, the experimental results of the CNIITMASH probe and the experimental results of a series of similar experiments performed by Sandia.

Swarms of mobile robots can be tasked with searching a geographic region for targets of interest, such as buried land mines. The authors assume that the individual robots are equipped with sensors tuned to the targets of interest, that these sensors have limited range, and that the robots can communicate with one another to enable cooperation. How can a swarm of cooperating sensate robots efficiently search a given geographic region for targets in the absence of a priori information about the target`s locations? Many of the obvious approaches are inefficient or lack robustness. One efficient approach is to have the robots traverse a space-filling curve. For many geographic search applications, this method is energy-frugal, highly robust, and provides guaranteed coverage in a finite time that decreases as the reciprocal of the number of robots sharing the search task. Furthermore, it minimizes the amount of robot-to-robot communication needed for the robots to organize their movements. This report presents some preliminary results from applying the Hilbert space-filling curve to geographic search by mobile robots.

Rapid Prototyping and Near Net Shape manufacturing technologies are the subject of considerable attention and development efforts. At Sandia National Laboratories, one such effort is LENS (Laser Engineered Net Shaping). The LENS process utilizes a stream of powder and a focused Nd YAG laser to build near net shape fully dense metal parts. In this process, a 3-D solid model is sliced, then an X-Y table is rastered under the beam to build each slice. The laser 1 powder head is incremented upward with each slice and the deposition process is controlled via shuttering of the laser. At present, this process is capable of producing fully dense metal parts of iron, nickel and titanium alloys including tool steels and aluminides. Tungsten components have also been produced. A unique aspect of this process is the ability to produce components wherein the composition varies at differing locations in the part. Such compositional variations may be accomplished in either a stepped or graded fashion. In this paper, the details of the process will be described. The deposition mechanism will be characterized and microstructures and their associated properties will be discussed. Examples of parts which have been produced will be shown and issues regarding dimensional control and surface finish will be addressed.

Of all the buried landmine identification technologies currently available, sensing the chemical signature from the explosive components found in landmines is the only technique that can classify non-explosive objects from the real threat. In the last two decades, advances in chemical detection methods has brought chemical sensing technology to the foreground as an emerging technological solution. In addition, advances have been made in the understanding of the fundamental transport processes that allow the chemical signature to migrate from the buried source to the ground surface. A systematic evaluation of the transport of the chemical signature from inside the mine into the soil environment, and through the soil to the ground surface is being explored to determine the constraints on the use of chemical sensing technology. This effort reports on the results of simulation modeling using a one-dimensional screening model to evaluate the impacts on the transport of the chemical signature by variation of some of the principal soil transport parameters.

This paper discusses rock mechanics testing of surrogate materials to provide failure criteria for compacted, degraded nuclear waste. This daunting proposition was approached by first assembling all known parameters such as the initial waste inventory and rock mechanics response of the underground setting after the waste is stored. Conservative assumptions allowing for extensive degradation processes helped quantify the lowest possible strength conditions of the future state of the waste. In the larger conceptual setting, computations involve degraded waste behavior in transient pressure gradients as gas exits the waste horizon into a wellbore. Therefore, a defensible evaluation of tensile strength is paramount for successful analyses and intentionally provided maximal failed volumes. The very conservative approach assumes rampant degradation to define waste surrogate composition. Specimens prepared from derivative degradation product were consolidated into simple geometries for rock mechanics testing. Tensile strength thus derived helped convince a skeptical peer review panel that drilling into the Waste Isolation Pilot Plant (WIPP) would not likely expel appreciable solids via the drill string.

The US Department of Energy`s (DOE) Mixed Waste Focus Area is developing a program to address and resolve issues associated with final waste form performance in treating and disposing of DOE`s mixed low-level waste (MLLW) inventory. A key issue for the program is identifying MLLW streams that may be problematic for disposal. Previous reports have quantified and qualified the capabilities of fifteen DOE sites for MLLW disposal and provided volume and radionuclide concentration estimates for treated MLLW based on the DOE inventory. Scoping-level analyses indicated that 101 waste streams identified in this report (approximately 6,250 m{sup 3} of the estimated total treated MLLW) had radionuclide concentrations that may make their disposal problematic. The radionuclide concentrations of these waste streams were compared with the waste acceptance criteria (WAC) for a DOE disposal facility at Hanford and for Envirocare`s commercial disposal facility for MLLW in Utah. Of the treated MLLW volume identified as potentially problematic, about 100 m{sup 3} exceeds the WAC for disposal at Hanford, and about 4,500 m{sup 3} exceeds the WAC for disposal at Envirocare. Approximately 7% of DOE`s total MLLW inventory has not been sufficiently characterized to identify a treatment process for the waste and was not included in the analysis. In addition, of the total treated MLLW volume, about 30% was associated with waste streams that did not have radionuclide concentration data and could not be included in the determination of potentially problematic waste streams.

The fate and transport of chemical signature molecules that emanate from buried landmines is strongly influenced by physical chemical properties and by environmental conditions of the specific chemical compounds. Published data have been evaluated as the input parameters that are used in the simulation of the fate and transport processes. A one-dimensional model developed for screening agricultural pesticides was modified and used to simulate the appearance of a surface flux above a buried landmine and estimate the subsurface total concentration. The physical chemical properties of TNT cause a majority of the mass released to the soil system to be bound to the solid phase soil particles. The majority of the transport occurs in the liquid phase with diffusion and evaporation driven advection of soil water as the primary mechanisms for the flux to the ground surface. The simulations provided herein should only be used for initial conceptual designs of chemical pre-concentration subsystems or complete detection systems. The physical processes modeled required necessary simplifying assumptions to allow for analytical solutions. Emerging numerical simulation tools will soon be available that should provide more realistic estimates that can be used to predict the success of landmine chemical detection surveys based on knowledge of the chemical and soil properties, and environmental conditions where the mines are buried. Additional measurements of the chemical properties in soils are also needed before a fully predictive approach can be confidently applied.

Under Sandia`s Laboratory Directed Research and Development (LDRD) program, novel acoustic wave-based sensors were explored for detecting gaseous chemical species in vehicle exhaust streams. The need exists for on-line, real-time monitors to continuously analyze the toxic exhaust gases -- nitrogen oxides (NOx), carbon monoxide (CO), and hydrocarbons (HC) -- for determining catalytic converter efficiency, documenting compliance to emission regulations, and optimizing engine performance through feedback control. In this project, the authors adapted existing acoustic wave chemical sensor technology to the high temperature environment and investigated new robust sensor materials for improving gas detection sensitivity and selectivity. This report describes one new sensor that has potential use as an exhaust stream residual hydrocarbon monitor. The sensor consists of a thickness shear mode (TSM) quartz resonator coated with a thin mesoporous silica layer ion-exchanged with palladium ions. When operated at temperatures above 300 C, the high surface area film catalyzes the combustion of the hydrocarbon vapors in the presence of oxygen. The sensor acts as a calorimeter as the exothermic reaction slightly increases the temperature, stressing the sensor surface, and producing a measurable deviation in the resonator frequency. Sensitivities as high as 0.44 (ppm-{Delta}f) and (ppm-gas) have been measured for propylene gas, with minimum detectable signals of < 50 ppm of propylene at 500 C.

This report covers the three phase effort to bring the SEA Corporation`s Powergrid{trademark} from the concept stage to pilot production. The three phases of this contract covered component development, prototype module development, and pilot line production. The Powergrid is a photovoltaic concentrator that generates direct current electricity directly from sunlight using a linear Fresnel lens. Analysis has shown that the Powergrid has the potential to be very low cost in volume production. Before the start of the project, only proof of concept demonstrations of the components had been completed. During the project, SEA Corporation developed a low cost extruded Fresnel lens, a low cost receiver assembly using one sun type cells, a low cost plastic module housing, a single axis tracking system and frame structure, and pilot production equipment and techniques. In addition, an 800 kW/yr pilot production rate was demonstrated and two 40 kW systems were manufactured and installed.

The US Department of Energy Office of Utility Technologies is planning a series of related projects that will seek to improve the integration of renewable energy generation with energy storage in modular systems. The Energy Storage Systems Program and the Photovoltaics Program at Sandia National Laboratories conducted meetings to solicit industry guidance and to create a set of recommendations for the proposed projects. Five possible projects were identified and a three pronged approach was recommended. The recommended approach includes preparing a storage technology handbook, analyzing data from currently fielded systems, and defining future user needs and application requirements.

This project was driven by the need to identify and provide unique, state-of-the-art solutions to the robotic path planning and precision motion execution problems that face automated processes such as welding and cutting using lasers. The initial LDRD proposal was for a full three years program with a schedule that would create a precision robotic platform capable of providing path planning and precision motion execution using sensor and graphical programming technologies as the first year milestone. Milestones for year two were centered in developing and deploying sensor technologies that support welding and cutting. And year three milestones included the integration of any developed sensors onto the robotic platform under software control to achieve autonomous control of laser welding and cutting processes. The work performed was directed at the goal of establishing a precision robotics platform with the capability to integrate graphical programming, CAD model based path planning, and motion execution under real-time sensor based control. This report covers the progress made toward that goal during the one year of funding.

Experimental cryogenic capabilities are essential for the study of ICF high-gain target and weapons effects issues involving dynamic materials response at low temperatures. This report describes progress during the period 2/97-11/97 on the FY97 LDRD project ``Cryogenic EOS Capabilities on Pulsed Radiation Sources (Z Pinch)``. The goal of this project is the development of a general purpose cryogenic target system for precision EOS and shock physics measurements at liquid helium temperatures on the Z accelerator Z-pinch pulsed radiation source. Activity during the FY97 LDRD phase of this project has focused on development of a conceptual design for the cryogenic target system based on consideration of physics, operational, and safety issues, design and fabrication of principal system components, construction and instrumentation of a cryogenic test facility for off-line thermal and optical testing at liquid helium temperatures, initial thermal testing of a cryogenic target assembly, and the design of a cryogenic system interface to the Z pulsed radiation source facility. The authors discuss these accomplishments as well as elements of the project that require further work.

Radiation response comparisons of lateral PNP bipolar technologies reveal that device hardening may be achieved by extending the emitter contact over the active base. The emitter-tied field plate suppresses recombination of carriers with interface traps.

To use the all-tetrahedral mesh generation existing today, the authors have explored the creation of a computationally efficient eight-node tetrahedral finite element (a four-node tetrahedral finite element enriched with four mid-face nodal points). The derivation of the element`s gradient operator, studies in obtaining a suitable mass lumping, and the element`s performance in applications are presented. In particular they examine the eight-node tetrahedral finite element`s behavior in longitudinal plane wave propagation, in transverse cylindrical wave propagation, and in simulating Taylor bar impacts. The element samples only constant strain states and, therefore, has 12 hour-glass modes. In this regard it bears similarities to the eight-node, mean-quadrature hexahedral finite element. Comparisons with the results obtained from the mean-quadrature eight-node hexahedral finite element and the four-node tetrahedral finite element are included. Given automatic all-tetrahedral meshing, the eight-node, constant-strain tetrahedral finite element is a suitable replacement for the eight-node hexahedral finite element in those cases where mesh generation requires an inordinate amount of user intervention and direction to obtain acceptable mesh properties.

Recently a large effort has been put into identifying solid acid materials, particularly sulfated zirconia and other sulfated metal oxides, that can be used to replace environmentally hazardous liquid acids in industrial processes. The authors are studying a group of mixed metal phosphates, some of which have also been sulfated, for their catalytic and morphological characteristics. Zirconium and titanium are the metals used in this study and the catalysts are synthesized from alkoxide starting materials with H{sub 3}PO{sub 4}, H{sub 2}O, and sometimes H{sub 2}SO{sub 4} as gelling agents. The measurement of acidity was achieved by using the isomerization of 2-methyl-2-pentene as a model reaction. The phosphate stabilized the mixed metal sulfates, preventing them from calcining to oxides boosting their initial catalytic activity. The addition of sulfate prevented the formation of the catalytically inactive mixed metal pyrophosphates when calcined at high temperatures (> 773 K).

The objective of this project is to develop the capability of symbolically generating an analytical model of a wind turbine for studies of control systems. This report focuses on a theoretical formulation of the symbolic equations of motion (EOMs) modeler for horizontal axis wind turbines. In addition to the power train dynamics, a generic 7-axis rotor assembly is used as the base model from which the EOMs of various turbine configurations can be derived. A systematic approach to generate the EOMs is presented using d`Alembert`s principle and Lagrangian dynamics. A Matlab M file was implemented to generate the EOMs of a two-bladed, free yaw wind turbine. The EOMs will be compared in the future to those of a similar wind turbine modeled with the YawDyn code for verification. This project was sponsored by Sandia National Laboratories as part of the Adaptive Structures and Control Task. This is the final report of Sandia Contract AS-0985.

Oxide trapped charge, field effects from emitter metallization, and high level injection phenomena moderate enhanced gain degradation of lateral pnp transistors at low dose rates. Hardness assurance tests at elevated irradiation temperatures require larger design margins for low power measurement biases.

This report provides a summary of the LDRD project titled: Electromagnetic impulse radar for the detection of underground structures. The project met all its milestones even with a tight two year schedule and total funding of $400 k. The goal of the LDRD was to develop and demonstrate a ground penetrating radar (GPR) that is based on high peak power, high repetition rate, and low center frequency impulses. The idea of this LDRD is that a high peak power, high average power radar based on the transmission of short impulses can be utilized effect can be utilized for ground penetrating radar. This direct time-domain system the authors are building seeks to increase penetration depth over conventional systems by using: (1) high peak power, high repetition rate operation that gives high average power, (2) low center frequencies that better penetrate the ground, and (3) short duration impulses that allow for the use of downward looking, low flying platforms that increase the power on target relative to a high flying platform. Specifically, chirped pulses that are a microsecond in duration require (because it is difficult to receive during transmit) platforms above 150 m (and typically 1 km) while this system, theoretically could be at 10 m above the ground. The power on target decays with distance squared so the ability to use low flying platforms is crucial to high penetration. Clutter is minimized by time gating the surface clutter return. Short impulses also allow gating (out) the coupling of the transmit and receive antennas.

The development of high current (I > 10 MA) drivers provides the authors with a new tool for the study of neutron-producing plasmas in the thermal regime. The imploded deuterium mass (or collisionality) increases as I{sup 2} and the ability of the driver to heat the plasma to relevant fusion temperatures improves as the power of the driver increases. Additionally, fast (<100 ns) implosions are more stable to the usual MHD instabilities that plagued the traditional slower implosions. The authors describe experiments in which deuterium gas puffs or CD{sub 2} fiber arrays were imploded in a fast z-pinch configuration on Sandia`s Saturn facility generating up to 3 {times} 10{sup 12} D-D neutrons. These experiments were designed to explore the physics of neutron-generating plasmas in a z-pinch geometry. Specifically, the authors intended to produce neutrons from a nearly thermal plasma where the electrons and ions have a nearly Maxwellian distribution. This is to be clearly differentiated from the more usual D-D beam-target neutrons generated in many dense plasma focus (DPF) devices.

Industrial ecology (IE) is an emerging scientific field that views industrial activities and the environment as an interactive whole. The IE approach simultaneously optimizes activities with respect to cost, performance, and environmental impact. Industrial Ecology provides a dynamic systems-based framework that enables management of human activity on a sustainable basis by: minimizing energy and materials usage; insuring acceptable quality of life for people; minimizing the ecological impact of human activity to levels that natural systems can sustain; and maintaining the economic viability of systems for industry, trade and commerce. Industrial ecology applies systems science to industrial systems, defining the system boundary to incorporate the natural world. Its overall goal is to optimize industrial activities within the constraints imposed by ecological viability, globally and locally. In this context, Industrial systems applies not just to private sector manufacturing and services but also to government operations, including provision of infrastructure. Sandia conducted its seventeenth Prosperity Game{trademark} on May 23--25, 1997, at the Hyatt Dulles Hotel in Herndon, Virginia. The primary sponsors of the event were Sandia National Laboratories and Los Alamos National Laboratory, who were interested in using the format of a Prosperity Game to address some of the issues surrounding Industrial Ecology. Honorary game sponsors were: The National Science Foundation; the Committee on Environmental Improvement, American Chemical Society; the Industrial and Engineering Chemistry Division, American Chemical Society; the US EPA--The Smart Growth Network, Office of Policy Development; and the US DOE-Center of Excellence for Sustainable Development.

This paper describes a method for transforming measured optical and infrared filter data for use with optical systems of arbitrary f-number and angle of incidence. Although it is generally desirable to have normal incidence at the filter (i.e., collimated light where an optical filter is used), other system design considerations may take precedence. In the case of a multispectral sensor under development at Sandia National Laboratories, system constraints require optical filter placement very near the focal plane. The light rays incident on the filters are therefore converging as determined by the system f-number while the chief ray of each ray bundle varies with focal plane position. To analyze the system`s spectral response at different points on the focal plane, a method was devised to transform the filter vendor`s measured data to account for the optical system design. The key to the transformation is the determination of weighting factors and shift factors for each angle of incidence making up a ray bundle. A computer worksheet was developed using a popular mathematical software package which performs this transformation for 75 key points on the focal plane.

This report documents a prototype tool developed to investigate the use of visualization and virtual reality technologies for improving software surety confidence. The tool is utilized within the execution phase of the software life cycle. It provides a capability to monitor an executing program against prespecified requirements constraints provided in a program written in the requirements specification language SAGE. The resulting Software Attribute Visual Analysis Tool (SAVAnT) also provides a technique to assess the completeness of a software specification.

The number of commercial airframes exceeding twenty years of service continues to grow. An unavoidable by-product of aircraft use is that crack and corrosion flaws develop throughout the aircraft`s skin and substructure elements. Economic barriers to the purchase of new aircraft have created an aging aircraft fleet and placed even greater demands on efficient and safe repair methods. Composite doublers, or repair patches, provide an innovative repair technique which can enhance the way aircraft are maintained. Instead of riveting multiple steel or aluminum plates to facilitate an aircraft repair, it is now possible to bond a single Boron-Epoxy composite doubler to the damaged structure. The composite doubler repair process produces both engineering and economic benefits. The FAA`s Airworthiness Assurance Center at Sandia National Labs completed a project to introduce composite doubler repair technology to the commercial aircraft industry. This paper focuses on a specialized structural test facility which was developed to evaluate the performance of composite doublers on actual aircraft structure. The facility can subject an aircraft fuselage section to a combined load environment of pressure (hoop stress) and axial, or longitudinal, stress. The tests simulate maximum cabin pressure loads and use a computerized feedback system to maintain the proper ratio between hoop and axial loads. Through the use of this full-scale test facility it was possible to: (1) assess general composite doubler response in representative flight load scenarios, and (2) verify the design and analysis approaches as applied to an L-1011 door corner repair.

Radiation-induced degradation of many types of bipolar transistors and circuits is more severe following low dose rate exposure than following high dose rate exposure. Since microelectronic devices in space are generally subjected to low dose rate irradiation, this complicates the hardness assurance testing of linear circuits and can lead to an overestimation of device lifetime in space. Previous work examining the physical mechanisms responsible for this dose rate effect has focused primarily on oxide trapped charge. Reduced net positive oxide trapped charge densities at high dose rates and zero bias have been attributed to space charge effects from slowly transporting holes trapped metastably at O vacancy complexes. Decreasing the dose rate or increasing the irradiation temperature leads to an increase in net positive oxide trapped charge near the Si-SiO{sub 2} interface by reducing these space charge effects. In this work, concentrations of hydrogen transport through two types of bipolar oxides are estimated from dopant passivation measurements in MOS capacitors. For unbiased irradiations, hydrogen passivation of substrate acceptors is greatly reduced at high dose rates compared to that at low dose rates or elevated temperatures. Consistent with other widely accepted models, it is argued that fewer interface traps are formed by high dose rate irradiation under zero bias, because fewer H{sup +} ions can drift to the Si-SiO{sub 2} interface and react with trap precursors. Similar to hole transport in these oxides, drift of the H{sup +} ions is inhibited at high dose rates by space charge accumulated in the oxide bulk.

In this work the basic Finite Element Tearing and Interconnecting (FETI) linear system solver and the PARPACK eigensolver are combined to compute the smallest modes of symmetric generalized eigenvalue problems that arise from structures modeled primarily by solid finite elements. Problems with over one million unknowns are solved. A comprehensive and relatively self-contained description of the FETI method is presented.

Results of two studies conducted as part of the Strategic Petroleum Reserve (SPR) Pipeline Corrosion Control Program are reported. These studies focused on evaluation of rotary-applied concrete materials for internal pipeline protection against the erosive and corrosive effects of flowing brine. The study also included evaluation of liners applied by hand on pipe pieces that cannot be lined by rotary methods. Such pipe pieces include tees, elbows and flanged pipe sections. Results are reported from a corrosion survey of 17 different liner formulations tested at the-Big-Rill SPR Site. Testing consisted of electrochemical corrosion rate measurements made on lined pipe sections exposed, in a test manifold, to flowing SPR generated fluids. Testing also involved cumulative immersion exposure where samples were exposed to static site-generated brine for increasing periods of time. Samples were returned to the laboratory for various diagnostic analyses. Results of this study showed that standard calcium silicate concrete (API RP10E) and a rotary calcium aluminate concrete formulation were excellent performers. Hand-lined pipe pieces did not provide as much corrosion protection. The focus of the second part of the study was on further evaluation of the calcium silicate, calcium aluminate and hand-applied liners in actual SPR equipment and service. It was a further objective to assess the practicality of electrochemical impedance spectroscopy (EIS) for field corrosion monitoring of concrete lined pipe compared to the more well-known linear polarization technique. This study showed that concrete linings reduced the corrosion rate for bare steel from 10 to 15 mils per year to 1 mil per year or less. Again, the hand-applied liners did not provide as much corrosion protection as the rotary-applied liners. The EIS technique was found to be robust for field corrosion measurements. Mechanistic and kinetic corrosion rate data were reliably obtained.

The conversion of small alkanes into alkenes represents an important chemical processing area; ethylene and propylene are the two most important organic chemicals manufactured in the U.S. These chemicals are currently manufactured by steam cracking of ethane and propane, an extremely energy intensive, nonselective process. The development of catalytic technologies (e.g., selective dehydrogenation) that can be used to produce ethylene and propylene from ethane and propane with greater selectivity and lower energy consumption than steam cracking will have a major impact on the chemical processing industry. This report details a study of two novel catalytic materials for the selective dehydrogenation of propane: Cr supported on hydrous titanium oxide ion-exchangers, and Pt nanoparticles encapsulated in silica and alumina aerogel and xerogel matrices.

The Analytical Chemistry Department uses a system of job cards to control and monitor the work through the organization. In the past, many different systems have been developed to allow each laboratory to monitor their individual work and report data. Unfortunately, these systems were separate and unique which caused difficulty in ascertaining any overall picture of the Department`s workload. To overcome these shortcomings, a new Job Card System was developed on Lotus Notes/Domino{trademark} for tracking the work through the laboratory. This application is groupware/database software and is located on the Sandia Intranet which allows users of any type of computer running a network browser to access the system. Security is provided through the use of logons and passwords for users who must add and/or modify information on the system. Customers may view the jobs in process by entering the system as an anonymous user. An overall view of the work in the department can be obtained by selecting from a variety of on screen reports. This enables the analysts, customers, customer contacts, and the Department Manager to quickly evaluate the work in process, the resources required, and the availability of equipment. On-line approval of the work and e-mail messaging of completed jobs has been provided to streamline the review and approval cycle. This paper provides a guide for the use of the Job Card System and information on maintenance of the system.

This report presents a nondestructive inspection assessment of eddy current and electrochemical analysis to separate inconel alloys from stainless steel alloys as well as an evaluation of cleaning techniques to remove a thermal oxide layer on aircraft exhaust components. The results of this assessment are presented in terms of how effective each technique classifies a known exhaust material. Results indicate that either inspection technique can separate inconel and stainless steel alloys. Based on the experiments conducted, the electrochemical spot test is the optimum for use by airframe and powerplant mechanics. A spot test procedure is proposed for incorporation into the Federal Aviation Administration Advisory Circular 65-9A Airframe & Powerplant Mechanic - General Handbook. 3 refs., 70 figs., 7 tabs.

An efficient method is presented for calculation of RMS von Mises stresses from stress component transfer functions and the Fourier representation of random input forces. An efficient implementation of the method calculates the RMS stresses directly from the linear stress and displacement modes. The key relation presented is one suggested in past literature, but does not appear to have been previously exploited in this manner.

This document is a reference guide for LHS, Sandia`s Latin Hypercube Sampling Software. This software has been developed to generate either Latin hypercube or random multivariate samples. The Latin hypercube technique employs a constrained sampling scheme, whereas random sampling corresponds to a simple Monte Carlo technique. The present program replaces the previous Latin hypercube sampling program developed at Sandia National Laboratories (SAND83-2365). This manual covers the theory behind stratified sampling as well as use of the LHS code both with the Windows graphical user interface and in the stand-alone mode.

Future generation automated human biometric identification and verification will require multiple features/sensors together with internal and external information sources to achieve high performance, accuracy, and reliability in uncontrolled environments. The primary objective of the proposed research is to develop a theoretical and practical basis for identifying and verifying people using standoff biometric features that can be obtained with minimal inconvenience during the verification process. The basic problem involves selecting sensors and discovering features that provide sufficient information to reliably verify a person`s identity under the uncertainties caused by measurement errors and tactics of uncooperative subjects. A system was developed for discovering hand, face, ear, and voice features and fusing them to verify the identity of people. The system obtains its robustness and reliability by fusing many coarse and easily measured features into a near minimal probability of error decision algorithm.

The goal of this research project was to create a passive and robust computer vision system for producing 3-D computer models of arbitrary scenes. Although the authors were unsuccessful in achieving the overall goal, several components of this research have shown significant potential. Of particular interest is the application of parametric eigenspace methods for planar pose measurement of partially occluded objects in gray-level images. The techniques presented provide a simple, accurate, and robust solution to the planar pose measurement problem. In addition, the representational efficiency of eigenspace methods used with gray-level features were successfully extended to binary features, which are less sensitive to illumination changes. The results of this research are presented in two papers that were written during the course of this project. The papers are included in sections 2 and 3. The first section of this report summarizes the 3-D modeling efforts.

Silicon wafers are coated with photoresist and exposed to ultraviolet (UV) light in a laboratory to simulate typical conditions expected in an actual semiconductor manufacturing process tool. Air is drawn through the exposure chamber and analyzed using chemical ionization mass spectrometry (CI/MS). Species that evaporate or outgas from the wafer are thus detected. The purpose of such analyses is to determine the potential of CI/MS as a real-time process monitoring tool. Results demonstrate that CI/MS can remotely detect the products evolved before, during, and after wafer UV exposure; and that the quantity and type of products vary with the photoresist coated on the wafer. Such monitoring could provide semiconductor manufacturers benefits in quality control and process analysis. Tool and photoresist manufacturers could also realize benefits from this measurement technique with respect to new tool, method, or photoresist development. The benefits realized can lead to improved device yields and reduced product and development costs.

In this introductory work, joint compliance is studied in both a numerical and experimental setting. A simple bolted interface is used as the test article and compliance is measured for the joint in both compression and in tension. This simple interface is shown to exhibit a strong non-linearity near the transition from compression to tension (or vice-versa). Modeling issues pertaining to numerically solving for the compliance are addressed. It is shown that the model predictions, in spite of convergence being very sensitive to numerical artifacts of the interface model, are in good agreement with experimentally measured strains and joint compliances. The joint behavior is a mechanical analogy to a diode, i.e., in compression, the joint is very stiff, acting almost as a rigid link, while in tension the joint is relatively soft, acting as a spring.

Recent advances in micro-science and technology, like Micro-Electro-Mechanical Systems (MEMS), have generated a group of unique liquid flow problems that involve characteristic length scales of a Micron. Also, in manufacturing processes such as coatings, current continuum models are unable to predict microscale physical phenomena that appear in these non-equilibrium systems. It is suspected that in these systems, molecular-level processes can control the interfacial energy and viscoelastic properties at the liquid/solid boundary. A massively parallel molecular dynamics (MD) code has been developed to better understand microscale transport mechanisms, fluid-structure interactions, and scale effects in micro-domains. Specifically, this MD code has been used to analyze liquid channel flow problems for a variety of channel widths, e.g. 0.005-0.05 microns. This report presents results from MD simulations of Poiseuille flow and Couette flow problems and addresses both scaling and modeling issues. For Poiseuille flow, the numerical predictions are compared with existing data to investigate the variation of the friction factor with channel width. For Couette flow, the numerical predictions are used to determine the degree of slip at the liquid/solid boundary. Finally, the results also indicate that shear direction with respect to the wall lattice orientation can be very important. Simulation results of microscale Couette flow and microscale Poiseuille flow for two different surface structures and two different shear directions will be presented.

Geotechnical structures such as underground bunkers, tunnels, and building foundations are subjected to stress fields produced by the gravity load on the structure and/or any overlying strata. These stress fields may be reproduced on a scaled model of the structure by proportionally increasing the gravity field through the use of a centrifuge. This technology can then be used to assess the vulnerability of various geotechnical structures to explosive loading. Applications of this technology include assessing the effectiveness of earth penetrating weapons, evaluating the vulnerability of various structures, counter-terrorism, and model validation. This document describes the development of expertise in scale model explosive testing on geotechnical structures using Sandia`s large scale centrifuge facility. This study focused on buried structures such as hardened storage bunkers or tunnels. Data from this study was used to evaluate the predictive capabilities of existing hydrocodes and structural dynamics codes developed at Sandia National Laboratories (such as Pronto/SPH, Pronto/CTH, and ALEGRA). 7 refs., 50 figs., 8 tabs.

A major advance contained in the new Fortran 90 language standard is the ability to define new data types and the operators associated with them. Writing computer code to implement computations with real and complex three-dimensional vectors and dyadics is greatly simplified if the equations can be implemented directly, without the need to code the vector arithmetic explicitly. The Fortran 90 module described here defines new data types for real and complex 3-dimensional vectors and dyadics, along with the common operations needed to work with these objects. Routines to allow convenient initialization and output of the new types are also included. In keeping with the philosophy of data abstraction, the details of the implementation of the data types are maintained private, and the functions and operators are made generic to simplify the combining of real, complex, single- and double-precision vectors and dyadics.

This report describes a Laboratory Directed Research and Development (LDRD) activity to develop a diagnostic technique for simultaneous temporal and spatial resolution of fluid flows. The goal is to obtain two orders of magnitude resolution in two spatial dimensions and time simultaneously. The approach used in this study is to scale up Particle Image Velocimetry (PIV) and Planar Laser Induced Fluorescence (PLIF) to acquire meter-size images at up to 200 frames/sec. Experiments were conducted in buoyant, fully turbulent, non-reacting and reacting plumes with a base diameter of one meter. The PIV results were successful in the ambient gas for all flows, and in the plume for non-reacting helium and reacting methane, but not reacting hydrogen. No PIV was obtained in the hot combustion product region as the seed particles chosen vaporized. Weak signals prevented PLIF in the helium. However, in reacting methane flows, PLIF images speculated to be from Poly-Aromatic-Hydrocarbons were obtained which mark the flame sheets. The results were unexpected and very insightful. A natural fluorescence from the seed particle vapor was also noted in the hydrogen tests.

A low-cost, thermally-activated, palladium-catalyzed metallization process was developed for rapid prototyping of polymeric electronic substrates and devices. The process was successfully applied in producing adhesiveless copper/polyimide laminates with high peel strengths and thick copper coating; copper/polyimide laminates are widely used in fabricating interconnects such as printed wiring boards (PWBs) and flexible circuits. Also successfully metallized using this low-cost metallization process were: (1) scaled-down models of radar-and-communication antenna and waveguide; (2) scaled-down model of pulsed-power-accelerator electrode; (3) three-dimensional micro-porous, open-cell vitreous carbon foams. Moreover, additive patterned metallization was successfully achieved by selectively printing or plotting the catalyst ink only on areas where metallization is desired, and by uniform thermal activation. Additive patterned metallization eliminates the time-consuming, costly and environmentally-unfriendly etching process that is routinely carried out in conventional subtractive patterned metallization. A metallization process via ultraviolet (UV) irradiation activation was also demonstrated. In this process palladium-catalyst solution is first uniformly coated onto the substrate. A masking pattern is used to cover the areas where metallization is not wanted. UV irradiation is applied uniformly to activate the palladium catalyst and to cure the polymer carrier in areas that are not covered by the mask. Metal is then deposited by electroless plating only or by a combination of electroless and electrolytic plating. This UV-activation technique is particularly useful in additive fine-line patterned metallization. Lastly, computer models for electrolytic and electroless plating processes were developed to provide guidance in plating-process design.

In the original report (Reference 1), to which this report is a supplement, the results of CONTAIN code calculations were presented for five thermal-hydraulic experiments performed in the NUPEC 1/4-scale model containment, including the International Standard Problem ISP-35. In the original report, calculated helium concentrations were presented per NUPEC`s specifications for ISP-35. In contrast, this supplemental report presents the helium concentrations on a conventional dry basis, which is physically consistent with the gas chromatography data. These conventionally defined dry helium concentrations are compared with the previously reported results and are found to exhibit trends that are more consistent with measured data. While agreement between the predicted results and data is substantially improved in general for the M-8-1 experiment using these helium concentrations as opposed to the ISP-35 specifications, general improvement in agreement is not observed in all cases.

The US Department of Energy (DOE) manages a multibillion dollar environmental management (EM) program. In June 1996, the Assistant Secretary of Energy for EM issued a memorandum with guidance and a vision for a ten year planning process for the EM Program. The purpose of this process, which became known as the Accelerated Cleanup: Focus on 2006, is to make step changes within the DOE complex regarding the approach for making meaningful environmental cleanup progress. To augment the process, Assistant Secretary requested the site contractors to engage in an effort to identify and evaluate integration alternatives for EM waste stream treatment, storage, and disposal (TSD) that would parallel the 2006 Plan. In October 1996, ten DOE contractor installations began the task of identifying alternative opportunities for low level radioactive waste (LLW). Cost effective, efficient solutions were necessary to meet all requirements associated with storing, characterizing, treating, packaging, transporting, and disposing of LLW while protecting the workers` health and safety, and minimizing impacts to the environment. To develop these solutions, a systems engineering approach was used to establish the baseline requirements, to develop alternatives, and to evaluate the alternatives. Key assumptions were that unique disposal capabilities exist within the DOE that must be maintained; private sector disposal capability for some LLW may not continue to exist into the foreseeable future; and decisions made by the LLW Team must be made on a system or complex wide basis to fully realize the potential cost and schedule benefits. This integration effort promoted more accurate waste volume estimates and forecasts; enhanced recognition of existing treatment, storage, and disposal capabilities and capacities; and improved identification of cost savings across the complex.

The Environmental Measurement-While-Drilling-Gamma Ray Spectrometer (EMWD-GRS) system represents an innovative blend of new and existing technology that provides real-time environmental and drill bit data during drilling operations. The EMWD-GRS technology was demonstrated at Savannah River Site (SRS) F-Area Retention Basin. The EMWD-GRS technology demonstration consisted of continuously monitoring for gamma-radiation-producing contamination while drilling two horizontal boreholes below the backfilled waste retention basin. These boreholes passed near previously sampled locations where concentrations of contaminant levels of cesium had been measured. Contaminant levels continuously recorded by the EMWD-GRS system during drilling were compared to contaminant levels previously determined through quantitative laboratory analysis of soil samples. The results show general agreement between the soil sampling and EMWD-GRS techniques for Cs-137. The EMWD-GRS system has been improved by the integration of an orientation sensor package for position sensing (PS) (EMWD-GRS/PS). This added feature gives the capability of calculating position, which is tied directly to EMWD-GRS sensor data obtained while drilling. The EMWD-GRS/PS system is described and the results of the field tests are presented.

Sandia National Laboratories is developing guidelines that outline the technical basis for relying on natural attenuation for the remediation of metals and radionuclide-contaminated soils and groundwaters at US Department of Energy (DOE) sites for those specific cases where natural processes are effective at ameliorating soil and groundwater toxicity. Remediation by monitored natural attenuation (MNA) requires a clear identification of the specific reaction(s) by which contaminant levels are made less available as well as considerable long-term monitoring. Central to MNA is the development of a conceptual model describing the biogeochemical behavior of contaminant(s) in the subsurface. The conceptual model will be used to make testable predictions of contaminant availability over time. In many cases, comparison between this prediction and field measurements will provide the test of whether MNA is to be implemented. As a result, development of the conceptual model should guide site characterization activities as well as long-term monitoring.

The unprecedented rate and scope of change in the commercial microelectronics industry presents a significant challenge to, and a significant opportunity for, achieving affordable superiority in defense electronics. A proactive approach to making the industry inherently more leveragable is discussed. Defense microelectronics is inexorably linked to the commercial semiconductor industry. This is obvious in the case of COTS (Commercial Off the Shelf parts) and MOTS (Modified--e.g., upscreened--Off the Shelf parts) as these parts are produced by the commercial industry. However, even captive defense integrated circuit lines building specialized parts are being forced by their dependence on a commercial-industry-driven supplier base to follow commercial product/process/design trends. The just released 1997 version of the Semiconductor Industry Association (SIA) National Technology Roadmap for Semiconductors (NTRS) describes the unprecedented changes occurring in the commercial industry. The industry is evolving from a more stable pre-1994 technology evolution to a discontinuous post-1997 technology evolution. The purpose of this paper is to discuss how these changes present both major challenges and major opportunities, for defense microelectronics, especially for applications involving long lifetimes, harsh environments and/or high consequences of failures.

This report documents a prototype tool developed to investigate the use of visualization and virtual reality technologies for improving software surety confidence. The tool is utilized within the execution phase of the software life cycle. It provides a capability to monitor an executing program against prespecified requirements constraints provided in a program written in the requirements specification language SAGE. The resulting Software Attribute Visual Analysis Tool (SAVAnT) also provides a technique to assess the completeness of a software specification. The prototype tool is described along with the requirements constraint language after a brief literature review is presented. Examples of how the tool can be used are also presented. In conclusion, the most significant advantage of this tool is to provide a first step in evaluating specification completeness, and to provide a more productive method for program comprehension and debugging. The expected payoff is increased software surety confidence, increased program comprehension, and reduced development and debugging time.

Twelve experiments were conducted to determine the effect of water filled targets on the penetration of tungsten long rods in terms of their residual mass and integrity. CTH hydrocode calculations were performed for each of the experiments to ensure that the erosion and breakup of the tungsten projectiles could be accurately reproduced. The CTH hydrocode predictions correlation well with the experimental results in most cases. Only 8% of the variance is unexplained. The slip interface between the rod and water was approximated in one of two ways: (1) using the CTH BLINT option in 2-D or (2) using a standard Eulerian mixed cells treatment. Results indicate that a 3-D BLINT algorithm is critical to predicting rod residual lengths. The authors were unable to reproduce rod fracture that occurred in every experiment where the water column exceeded 25 cm in length. The authors feel that this is due to a change in rod material properties during penetration, and continue to investigate the issue.

The CTH Eulerian hydrocode, and the SPHINX smooth particle hydrodynamics (SPH) code were used to model a shock tube, two long rod penetrations into semi-infinite steel targets, and a long rod penetration into a spaced plate array. The results were then compared to experimental data. Both SPHINX and CTH modeled the one-dimensional shock tube problem well. Both codes did a reasonable job in modeling the outcome of the axisymmetric rod impact problem. Neither code correctly reproduced the depth of penetration in both experiments. In the 3-D problem, both codes reasonably replicated the penetration of the rod through the first plate. After this, however, the predictions of both codes began to diverge from the results seen in the experiment. In terms of computer resources, the run times are problem dependent, and are discussed in the text.

As part of the FAA`s National Aging Aircraft Research Program to foster new technologies for civil aircraft maintenance and repair, use of bonded composite doublers on metal aircraft structures has been advanced. Research and validation of such doubler applications on US certified commercial aircraft has begun. A specific composite application to assess the capabilities of composite doublers was chosen on a L-1011 aircraft for reinforcement of the comer of a cargo door frame where a boron-epoxy repair patch of up to 72 plies was installed. A primary inspection requirement for these doublers is the identification of disbonds between the composite laminate and the aluminum parent material. This paper describes the development of an ultrasonic pulse echo technique using a modified immersion focus transducer where a robust signal amplitude signature of the composite aluminum interface is obtained to characterize the condition of the bond. Example waveforms and C-scan images are shown to illustrate the ultrasonic response for various transducer configurations using a boron-epoxy aluminum skin calibration test sample where disbonds and delaminations were built-in. The modified focus transducer is compatible with portable ultrasonic scanning systems that utilize the weeper or dripless bubbler technologies when an ultrasonic inspection of the boron-epoxy composite doublers installed on aircraft is implemented.

An eddy current inspection method was developed at the Federal Aviation Administration`s Airworthiness Assurance NDI Validation Center (AANC) to easily and rapidly detect subsurface fatigue cracks in the wheel well fairing on the US Coast Guard (USCG) HC-130H aircraft caused by fatigue. The inspection procedure locates cracks as small as 10.2 millimeters in length at 2.54 mm below the skin surface at raised fastener sites. The test procedure developed baseline three USCG aircraft. Inspection results on the three aircraft reveals good correlation with results made during subsequent structural disassembly.

GaN MIS diodes were demonstrated utilizing AlN and Ga{sub 2}O{sub 3}(Gd{sub 2}O{sub 3}) as insulators. A 345 {angstrom} of AlN was grown on the MOCVD grown n-GaN in a MOMBE system using trimethylamine alane as Al precursor and nitrogen generated from a wavemat ECR N2 plasma. For the Ga{sub 2}O{sub 3}(Gd{sub 2}O{sub 3}) growth, a multi MBE chamber was used and a 195 {angstrom} oxide is E-beam evaporated from a single crystal source of Ga{sub 5}Gd{sub 3}O{sub 12}. The forward breakdown voltage of AlN and Ga{sub 2}O{sub 3}(Gd{sub 2}O{sub 3}) diodes are 5V and 6V, respectively, which are significantly improved from {approximately} 1.2 V of schottky contact. From the C-V measurements, both kinds of diodes showed good charge modulation from accumulation to depletion at different frequencies. The insulator GaN interface roughness and the thickness of the insulator were measured with x-ray reflectivity.

In the past thirty-six months, tremendous strides have been made in x-ray production using high-current z-pinches. Today, the x-ray energy (1.9 MJ) and power (200 TW) output of the Z accelerator (formerly PBFA-II) is the largest available in the laboratory. These z-pinch x-ray sources are being developed for research into the physics of high energy density plasmas of interest in weapon behavior and in inertial confinement fusion. Beyond the Z accelerator current of 20 MA, an extrapolation to the X-1 accelerator level of 60 MA may have the potential to drive high-yield ICF reactions at affordable cost if several challenging technical problems can be overcome. New developments have also taken place at Sandia in the area of high current, mm-diameter electron beams for advanced hydrodynamic radiography. On SABRE, x-ray spot diameters were less than 2 mm with a dose of 100 R at 1 meter in a 40 ns pulse.

Prosperity Games TM are an outgrowth and adaptation move/countermove and seminar War Games. Prosperity Games TM are simulations that explore complex issues in a variety of areas including economics, politics, sociology, environment, education, and research. These issues can be examined from a variety of perspectives ranging from a global, macroeconomic and geopolitical viewpoint down to the details of customer/supplier/market interactions in specific industries. All Prosperity Games TM are unique in that both the game format and the player contributions vary from game to game. This report documents the Industry Partnership Prosperity Game sponsored by the Technology Partnerships and Commercialization Center at Sandia National Laboratories. Players came from the Sandia line organizations, the Sandia business development and technology partnerships organizations, the US Department of Energy, academia, and industry The primary objectives of this game were to: explore ways to increase industry partnerships to meet long-term Sandia goals; improve Sandia business development and marketing strategies and tactics; improve the process by which Sandia develops long-term strategic alliances. The game actions and recommendations of these players provided valuable insights as to what Sandia can do to meet these objectives.

LDRD research activities have focused on increasing the robustness and efficiency of optimization studies for computationally complex engineering problems. Engineering applications can be characterized by extreme computational expense, lack of gradient information, discrete parameters, non-converging simulations, and nonsmooth, multimodal, and discontinuous response variations. Guided by these challenges, the LDRD research activities have developed application-specific techniques, fundamental optimization algorithms, multilevel hybrid and sequential approximate optimization strategies, parallel processing approaches, and automatic differentiation and adjoint augmentation methods. This report surveys these activities and summarizes the key findings and recommendations.

During the 1980s Sandia designed, developed, fabricated, tested, and delivered hundreds of thousands of radiation hardened Integrated Circuits (IC) for use in weapons and satellites. Initially, Sandia carried out all phases, design through delivery, so that development of next generation ICs and production of current generation circuits were carried out simultaneously. All this changed in the mid-eighties when an outside contractor was brought in to produce ICs that Sandia developed, in effect creating a crisp separation between development and production. This partnership had a severe impact on operations, but its more damaging effect was the degradation of Sandia`s microelectronics capabilities. This report outlines microelectronics development and production in the early eighties and summarizes the impact of changing to a separate contractor for production. This record suggests that low volume production be best accomplished within the development organization.

This report describes the results of composites fabrication research sponsored by the Laboratory Directed Research and Development (LDRD) program at Sandia National Laboratories. They have developed, prototyped, and demonstrated the feasibility of a novel robotic technique for rapid fabrication of composite structures. Its chief innovation is that, unlike all other available fabrication methods, it does not require a mold. Instead, the structure is built patch by patch, using a rapidly reconfigurable forming surface, and a robot to position the evolving part. Both of these components are programmable, so only the control software needs to be changed to produce a new shape. Hence it should be possible to automatically program the system to produce a shape directly from an electronic model of it. It is therefore likely that the method will enable faster and less expensive fabrication of composites.

In the assessment of a system, understanding the system is central. Even so, most of the current literature takes a narrow view of understanding, making only the catalog of system ``assets`` explicit, while maintaining the balance of the analyst`s understanding inside the analyst`s head. This can lead to problems with non-repeatability and incompleteness of assessment results. This paper introduces the notion of using explicit system models to document the analyst`s understanding of the system and shows that, from these models, standard assessment products, such as fault trees and event trees, can be automatically derived. This paper also presents five ``views`` of a system that can be used to document the analyst`s understanding of the system. These views go well beyond the standard instruction to identify the system`s assets to show that a much richer understanding of the system can be required for effective assessment.

In parameter estimation considerable insight is provided by examining sensitivity coefficients. This paper focuses on the use of sensitivity coefficients in connection with estimating thermal properties in the heat conduction equation. A general methodology for computing sensitivity coefficients can be an important design tool. The use of such a tool is demonstrated in this paper. A control volume, finite element program is used, and briefly described, to implement numerical sensitivity coefficient calculations. In this approach general problems can be studied. Several example problems are presented to demonstrate the insight gained from sensitivity coefficients. The problems are selected from experimental studies to characterize the thermal properties of carbon-carbon composite. Sensitivity coefficients show that in an experiment that is not well designed, additional materials in the experimental configuration can have a larger impact on the temperature than the material of interest. Two-dimensional configurations demonstrate that there can be isolated areas of insensitivity and the difficulty of estimating multiple parameters.

Effective use of resources that are shared among multiple products or processes is critical for agile manufacturing. This paper describes the development and implementation of a computerized model to support production planning in a complex manufacturing system at the Pantex Plant, a US Department of Energy facility. The model integrates two different production processes (nuclear weapon disposal and stockpile evaluation) that use common facilities and personnel at the plant. The two production processes are characteristic of flow-shop and job shop operations. The model reflects the interactions of scheduling constraints, material flow constraints, and the availability of required technicians and facilities. Operational results show significant productivity increases from use of the model.

Capacitance-voltage and thermally-stimulated-current techniques are used to estimate trapped hole and electron densities in MOS oxides as functions of irradiation and isochronal anneal temperature. Trapped-charge annealing and compensation effects are discussed.

Highly porous sol-gel films have potential applications as electrical and thermal insulators, catalyst supports, sensors, and membranes for gas separations. Pore dimensions in these sol-gel films are usually small e.g., on the order of tens of nanometers or less. Their successful fabrications, however, greatly depend on the fundamental understanding of mechanisms that underlie the phenomena of pore evolution, network shrinkage, and stress development since the final microstructure of a solid gel film is strongly affected by composition of its starting sol and its processing conditions. This report documents a simplified one-dimensional analysis of drying a solidifying sol-gel thin film coating supported by an impermeable solid substrate. Portions of this work were presented at the 1994 Annual Joint Meeting of the New Mexico Section of the American Ceramic Society and Materials Research Society in Albuquerque. The authors considered the solid/liquid two phase coexistent regime during the drying solidifying process in which solvent is removed continuously via evaporation, the solid phase grows significantly in mechanical strength, and pore space shrinks appreciably. From overall and differential mass balances and a force balance at equilibrium, coupled with empirical correlations of solid phase modulus and permeability to strain or deformation, the authors followed the evolution of pore space, solid phase elastic stress, and liquid phase hydrodynamic pressure; they also determined their respective values at equilibrium. By assuming microscopic pore shape models, they estimated and compared the predicted mean pore radii. Their simplified one-dimensional analysis shows that the final mean pore radius is controlled by four parameters: pore-liquid surface tension, solid phase modulus, mean pore radius, and porosity at the initial stress-free state. The one-dimensional model can be employed to guide process design and optimization in sol-gel film fabrications.

Practical work of adhesion measurements are being studied for several types of polymer/metal combinations in order to obtain a better understanding of the adhesive failure mechanisms for systems containing encapsulated and bonded components. The primary question is whether studies of model systems can be extended to systems of technological interest. The authors report on their first attempts to obtain the work of adhesion between a PDMS polymer and stainless steel. The work of adhesion measurements were made using three techniques -- contact angle, adhesive fracture energy at low deformation rates and JKR. Previous work by Whitesides` group show a good correlation between JKR and contact angle measurements for PDMS. Their initial work focused on duplicating the PDMS measurements of Chaudury. In addition, in this paper the authors extend the work of adhesion measurement to third technique -- interfacial failure energy. The ability to determine the reversible work of adhesion for practical adhesive joints allows understanding of several issues that control adhesion: surface preparation, nature of the interphase region, and bond durability.

Gate oxide electric fields are expected to increase to greater than 5 MV/cm as feature size approaches 0.1 micrometers in advanced integrated circuit (IC) technologies. Work by Johnston, et al. raised the concern that single event gate rupture (SEGR) may limit the scaling of advanced ICs for space applications. SEGR has also been observed in field programmable gate arrays, which rely on thin dielectrics for electrical programming at very high electric fields. The focus of this effort is to further explore the mechanisms for SEGR in thin gate oxides. The authors examine the characteristics of heavy ion induced breakdown and compare them to ion induced damage in thin gate oxides. Further, the authors study the impact of precursor damage in oxides on SEGR threshold. Finally, they compare thermal and nitrided oxides to see if SEGR is improved by incorporating nitrogen in the oxide.

Sandia National Laboratories has initiated many joint research and development projects with the two premier Russian nuclear laboratories, VNIIEF and VNIITF, (historically known as Arzamas-16 and Chelyabinsk-70) in a wide spectrum of areas. One of the areas in which critical dialogue and technical exchange is continuing to take place is in the realm of system surety. Activities primarily include either safety or security methodology development, processes, accident environment analyses and testing, accident data-bases, assessments, and product design. Furthermore, a continuing dialog has been established between the organizations with regard to developing a better understanding of how risk is perceived and analyzed in Russia versus that in the US. The result of such efforts could reduce the risk of systems to incur accidents or incidents resulting in high consequences to the public. The purpose of this paper is to provide a current overview of the Sandia surety program and its various initiatives with the Russian institutes, with an emphasis on the program scope and rationale. The historical scope of projects will be indicated. A few specific projects will be discussed, along with results to date. The extension of the joint surety initiatives to other government and industry organizations will be described. This will include the current status of a joint Sandia/VNIIEF initiative to establish an International Surety Center for Energy Intensive and High Consequence Systems and Infrastructures.

Preliminary work is presented on an effort to generate synthetic constitutive data for random composite materials. The long-ranged goal is to use the overall response determined from finite element simulations of representative volumes (RV) of the heterogeneous material to construct a homogenized constitutive model. A simple composite of a matrix containing polydispersed spheres was chosen as the first configuration to simulate. Here the accuracy of the numerical simulation tools is tested by determining effective elastic constants of the ordered elastic composite in which equal-sized spheres are arranged in each of three cubic lattice configurations. The resulting anisotropic effective elastic constant values agree with theoretical results to better than 10%, with typical agreement being better than 4%.

The thermal conduction of a portion of an enhanced surface heat exchanger for a gas fired heat pipe solar receiver was modeled using the boundary element and finite element methods (BEM and FEM) to determine the effect of weld fillet size on performance of a stud welded pin fin. A process that could be utilized by others for designing the surface mesh on an object of interest, performing a conversion from the mesh into the input format utilized by the BEM code, obtaining output on the surface of the object, and displaying visual results was developed. It was determined that the weld fillet on the pin fin significantly enhanced the heat performance, improving the operating margin of the heat exchanger. The performance of the BEM program on the pin fin was measured (as computational time) and used as a performance comparison with the FEM model. Given similar surface element densities, the BEM method took longer to get a solution than the FEM method. The FEM method creates a sparse matrix that scales in storage and computation as the number of nodes (N), whereas the BEM method scales as N{sup 2} in storage and N{sup 3} in computation.

This paper explores one woman`s journey through her recent promotion into management, and will identify key factors that helped prepare and position her to be ready to exercise leadership through a formal management role. It discusses assessment of qualifications and skills, acquisition of needed skills, the influence of luck and timing, and the use of mentors and delegation as survival skills to get through the transition period and become fully functional as a manager. It also includes insights into sensitive issues such as how to relate to former peers, how to gain credibility as the junior member of the management team, and how to juggle family responsibilities with increased time commitments at work. It emphasizes the importance of acknowledging the help the authors receive in reaching their own career goals and offering the same kind of help and support to those in the early stages of their careers.

No abstract available.

No abstract available.

The traditional method for determination of alpha-emitting isotopes on air filters has been to process the samples by radiochemical methods. However, this method is too slow for incidents involving radioactive materials where the determination of personnel dose is urgent. A method is developed to directly analyze the air filters taken from personal and area air monitors. The site knowledge is used in combination with alpha-spectral information to identify isotopes. A mathematical function is developed to estimate the activity for each isotope. The strengths and weaknesses of the method are discussed.

The radioisotope 99mTc, used in greater than 80% of nuclear medicine applications, has traditionally been produced and supplied to radiopharmaceutical companies in the form of its precursor 99Mo. Nuclear fission produced 99Mo had been supplied by Nordion International of Canada and Cintichem, Inc. of New York, USA. With the shutdown of Cintichem's reactor in 1989, a need was recognized for a US supply, and the US Department of Energy recently published a record of decision designating Sandia National Laboratories (SNL) to meet that need. A recent campaign was launched which utilized the SNL Annular Core Research Reactor to irradiate UO2 coated targets fabricated by Los Alamos National Laboratory to produce 99Mo. The irradiated targets were chemically processed in the SNL Hot Cell Facility to separate and purify the 99Mo. The campaign also included final product quality analysis, and process waste handling. The campaign was accomplished with high 99Mo recovery. Final product quality was assessed at SNL, and samples were sent to an outside laboratory for independent verification. The campaign provided data and experience useful in pursuing US Food and Drug Administration and radiopharmaceutical company approval. © 1998 Akadémiai Kiadó, All rights reserved.

The reliability of microengines is a function of the design of the mechanical linkage used to connect the electrostatic actuator to the drive. We have completed a series of reliability stress tests on surface micromachined microengines driving an inertial load. In these experiments, we used microengines that had pin mechanisms with guides connecting the drive arms to the electrostatic actuators. Comparing this data to previous results using flexure linkages revealed that the pin linkage design was less reliable. The devices were stressed to failure at eight frequencies, both above and below the measured resonance frequency of the microengine. Significant amounts of wear debris were observed both around the hub and pin joint of the drive gear. Additionally, wear tracks were observed in the area where the moving shuttle rubbed against the guides of the pin linkage. At each frequency, we analyzed the statistical data yielding a lifetime (t50) for median cycles to failure and σ, the shape parameter of the distribution. A model was developed to describe the failure data based on fundamental wear mechanisms and forces exhibited in mechanical resonant systems. The comparison to the model will be discussed.

The monolithic integration of MicroElectroMechanical Systems (MEMS) with the driving, controlling, and signal processing electronics promises to improve the performance of micromechanical devices as well as lower their manufacturing, packaging, and instrumentation costs. Key to this integration is the proper interleaving, combining, and customizing of the manufacturing processes to produce functional integrated micromechanical devices with electronics. We have developed a MEMS-first monolothic integrated process that first seals the micromechanical devices in a planarized trench and then builds the electronics in a conventional CMOS process. To date, most of the research published on this technology has focused on the performance characteristics of the mechanical portion of the devices, with little information on the attributes of the accompanying electronics. This work attempts to reduce this information void by presenting the results of SPICE Level 3 and BSIM3v3.1 model parameters extracted for the CMOS portion of the MEMS-first process. Transistor-level simulations of MOSFET current, capacitance, output resistance, and transconductance versus voltage using the extracted model parameters closely match the measured data. Moreover, in model validation efforts, circuit-level simulation values for the average gate propagation delay in a 101-stage ring oscillator are within 13-18% of the measured data. These results establish the following: (1) the MEMS-first approach produces functional CMOS devices integrated on a single chip with MEMS devices and (2) the devices manufactured in the approach have excellent transistor characteristics. Thus, the MEMS-first approach renders a solid technology foundation for customers designing in the technology.

The Southwest Surety Institute was formed in June, 1996 by Arizona State University (ASU), New Mexico Institute of Mining and Technology (NM Tech), New Mexico State University (NMSU), and Sandia National Laboratories (SNL) to provide new educational programs in Security Engineering. This is the first science-based program of its kind in the United States, directed at educating Security Engineers to help government and industry address their security needs. Current courses include security system design, evaluation, principles, and technology, the criminal justice system, and each member brings a unique educational capability to the institute. NMSU provides a security technology minor, merging programs in Criminal Justice and Electronics Technology. NM Tech has a formidable explosives testing and evaluation facility. ASU is developing a masters program in Security Engineering at their School of Technology located on a new campus in Mesa, Arizona. The Sandia National Laboratories security system design and evaluation process forms the basis for the security engineering curricula. In an effort to leverage the special capabilities of each university, distance education will be used to share courses among institute members and eventually with other sites across the country. The Institute will also pursue research and development funding in the areas of physical security information security, computer modeling and analysis, and counter-terrorist technology. Individual Institute members are currently working with sponsors from government and industry in areas such as counter-terrorism, microelectronics, banking, aviation, and sensor development.

Design and analysis of physical protection systems requires (1) identification of mission critical assets, (2) identification of potential threats that might undermine mission capability; (3) identification of the consequences of loss of mission-critical assets (e.g., time and cost to recover required capability and impact on operational readiness), and (4) analysis of the effectiveness of physical protection elements. CPA (cost and performance analysis) addresses the fourth of these four issues. CPA is a methodology that joins activity based cost estimation with performance-based analysis of physical protection systems. CPA offers system managers an approach that supports both tactical decision making and strategic planning. Current exploratory applications of the CPA methodology address analysis of alternative conceptual designs. Hypothetical data is used to illustrate this process.

We discuss the development, design and operation of a walk-through trace detection portal designed to screen personnel for explosives. Developed at Sandia National Laboratories (SNL) with primary funding from the Federal Aviation Administration (FAA) and additional support from the Department of Energy Office of Safeguards and Security, this portal is intended primarily for use in airport terminals and in other localities where a very high throughput of pedestrian traffic is combined with stringent security requirements. The portal is capable of detecting both vapor and particulate contamination, with the collection of explosive material being based upon the entrainment of that material in air flows over the body of the person being screened. This portal is capable of detecting high explosives of interest to the FAA. We discuss the results of field testing of the portal in the Albuquerque International Airport in September, 1997 and more recent steps towards commercialization of the portal.

A reliable micro gas pump is an essential element to the development of many micro-systems for chemical gas analyses. At Sandia, we are exploring a different pumping mechanism, gas transport by thermal transpiration. Thermal transpiration refers to the rarefied gas dynamics developed in a micro-channel with a longitudinal temperature gradient. To investigate the potential of thermal transpiration for gas pumping in micro-systems, we have performed simulations and model analysis to design micro-devices and to assess their design performance before the fabrication process. Our effort is to apply ICARUS (a Direct Simulation Monte Carlo code developed at Sandia) to characterize the fluid transport and evaluate the design performance. The design being considered has two plenums at different temperatures (hot and cold) separated by a micro-channel of 0.1 micron wide and 1 micron long. The temperature difference between the two plenums is 30 Kelvin. ICARUS results, a quasi-steady analysis, predicts a net flow through the micro-channel with a velocity magnitude of about 0.4 m/s due to temperature gradient at the wall (thermal creep flow) at the early time. Later as the pressure builds up in the hot plenum, flow is reversed. Eventually when the system reaches steady state equilibrium, the net flow becomes zero. The thermal creep effect is compensated by the thermo-molecular pressure effect. This result demonstrates that it is important to include the thermo-molecular pressure effect when designing a pumping mechanism based on thermal transpiration. The DSMC technique can model this complex thermal transpiration problem.

This paper summarizes results of metal cutting tests using an actively damped boring bar to suppress regenerative chatter. PZT stack actuators were integrated into a commercially available two-inch diameter boring bar to suppress bending vibrations. Since the modified tool requires no specialized mounting hardware, it can be readily mounted on a variety of machines. A cutting test using the prototype bar to remove metal from a hardened steel workpiece verifies that the actively damped tool yields significant vibration reduction and improved surface finish as compared to the open-loop case. In addition, the overall performance of the prototype bar is compared to that of an unmodified bar of pristine geometry, revealing that a significant enlargement of the stable machining envelope is obtained through application of feedback control.

This paper summarizes the design, modeling, and initial evaluation of a hinged structure for friction measurement in surface micromachining technology. While the area requirements are small, the present structure allows a much larger velocity and pressure range to be evaluated as compared to comb drive structures. The device consists of a cantilevered driver beam connected to a friction pad through a strategically located hinge. AC excitation of the beam flexure forces axial sliding of the friction pad due to beam foreshortening. Normal force is controlled by DC voltage on wings adjacent to the friction pad. While the achievable slip is small (10-30 nm), it is sufficient to disengage contacting asperities and engage new points of contact, and thus should be representative of frictional processes. Furthermore, the design enables the friction pad contact area to remain relatively constant over the excitation cycle. Computer simulation results are provided to mimic on-going experimental work. Increased friction forces are shown to enhance the size of hysteresis loops relating beam deflection to driver voltage.

A variety of tomographic techniques that have been applied to multiphase flows are described. The methods discussed include electrical impedance tomography (EIT), magnetic resonance imaging (MRI), positron emission tomography (PET), gamma-densitometry tomography (GDT), radiative particle tracking (RDT), X-ray imaging, and acoustic tomography. Also presented is a case study in which measurements were made with EIT and GDT in two-phase flows. Both solid-liquid and gas-liquid flows were examined. EIT and GDT were applied independently to predict mean and spatially resolved phase volume fractions. The results from the two systems compared well.

A microscale gas chromatography column is one component in a microscale chemistry laboratory for detecting chemical agents. Several columns were fabricated using the Bosch etch process which allows deep, high aspect ratio channels of rectangular cross-section. A design tool, based on analytical models, was developed to evaluate the effects of operating conditions and column specifications on separation resolution and time. The effects of slip flow, channel configuration, and cross-sectional shape were included to evaluate the differences between conventional round, straight columns and the microscale rectangular, spiral columns. Experimental data were obtained and compared with the predicted flowrates and theoretical number of plates. The design tool was then employed to select more optimum channel dimensions and operating conditions for high resolution separations.

The response and operation of a heat flux gage is studied using sensitivity analysis. Sensitivity analysis is the process by which one determines the sensitivity of a model output to changes in the model parameters. This process uses sensitivity coefficients, which are defined as partial derivatives of field variables (e.g. temperature) with respect to model parameters (e.g. thermal properties and boundary conditions). Computing sensitivity coefficients, in addition to the response of a heat flux gage, AIDS in identifying model parameters that significantly impact the temperature response. A control volume finite element based code is used to implement numerical sensitivity coefficient calculations, allowing general problems to be studied. Sensitivity coefficients are discussed for the well known Gardon gage.

Equations are presented to describe the sensitivity of the temperature field in a heat conducting body to changes in the volumetric heat source and volumetric heat capacity. These sensitivity equations, along with others not presented, are applied to a thermal battery problem to compute the sensitivity of the temperature field to 19 model input parameters. Sensitivity coefficients, along with assumed standard deviation in these parameters, are used to estimate the uncertainty in the temperature prediction. From the 19 parameters investigated, the battery cell heat source and volumetric heat capacity were clearly identified as being the major contributors to the overall uncertainty in the temperature predictions. The predicted operational life of the thermal battery was shown to be very sensitive to uncertainty in these parameters.

Research is underway to develop a 75-kW heat pipe to transfer solar energy from the focus of a parabolic dish concentrator to the heater tubes of a Stirling engine. The high flux levels and high total power level encountered in this application have made it necessary to use a high-performance wick structure with fibers on the order of 4 to 8 microns in diameter. This fine wick structure is highly susceptible to corrosion damage and plugging, as dissolved contaminants plate out on the evaporator surface. Normal operation of the heat pipe also tends to concentrate contaminants in localized areas of the evaporator surface where heat fluxes are the highest. Sandia National Laboratories is conducting a systematic study to identify procedures that reduce corrosion and contamination problems in liquid-metal heat pipes. A series of heat pipes are being tested to explore different options for cleaning heat-pipe systems. Models are being developed to help understand the overall importance of operating parameters on the life of heat-pipe systems. In this paper, we present our efforts to reduce corrosion damage.

This study compares the moduli and stresses obtained from dynamic measurements (e.g., logs or tomograms) and static tests (microfracture stress tests, core tri-axial compression tests) at M-Site, where there is a full suite of both types of data as well as other supporting information. The study shows that the dynamic moduli and log-derived stresses are considerably different from the measured in situ values as determined from microfracture stress tests. 2-D images of moduli and stress were also calculated from p-wave and s-wave tomograms, but the primary value of these results is in the qualitative description of the reservoir. The choice of modulus and stress values has a significant effect on processes such as hydraulic fracturing.

We are interested in the stability of three-dimensional fluid flows to small disturbances. One computational approach is to solve a sequence of large sparse generalized eigenvalue problems for the leading modes that arise from discretizating the differential equations modeling the flow. The modes of interest are the eigenvalues of largest real part and their associated eigenvectors. We discuss our work to develop an efficient and reliable eigensolver for use by the massively parallel simulation code MPSalsa. MPSalsa allows simulation of complex 3D fluid flow, heat transfer, and mass transfer with detailed bulk fluid and surface chemical reaction kinetics.

A linear least-squares procedure for the determination of modal residues using time-domain system realization theory is presented. The present procedure is intended to complement existing techniques for time-domain system identification and is shown to be theoretically equivalent to residue determination in realization algorithms such as the eigensystem realization algorithm and Q-Markov covariance equivalent realization method. However, isolating the optimal residue estimation problem from the general realization problem affords several alternative strategies as compared to standard realization algorithms for structural dynamics identification. Primary among these are alternative techniques for handling data sets with large numbers of sensors using small numbers of reference point responses and the inclusion of terms that accurately model the effects of residual flexibility. The accuracy and efficiency of the present realization theory-based procedure is demonstrated for both simulated and experimental data.

In order for the rapidly emerging field of MicroElectroMechanical Systems (MEMS) to meet its extraordinary expectations regarding commercial impact, issues pertaining to how they fail must be understood. We identify failure modes common to a broad range of MEMS actuators, including adhesion (stiction) and friction-induced failures caused by improper operational methods, mechanical instabilities, and electrical instabilities. Demonstrated methods to mitigate these failure modes include implementing optimized designs, model-based operational methods, and chemical surface treatments.

The fluid and particle dynamics of a high-velocity oxygen fuel (HVOF) thermal spray torch are analyzed using computational and experimental techniques. Three-dimensional computational fluid dynamics (CFD) results are presented for a curved aircap used for coating interior surfaces such as engine cylinder bores. The device analyzed is similar to the Metco diamond jet rotating wire (DJRW) torch. The feed gases are injected through an axisymmetric nozzle into the curved aircap. Premixed propylene and oxygen are introduced from an annulus in the nozzle, while cooling air is injected between the nozzle and the interior wall of the aircap. The combustion process is modeled using a single-step, finite-rate chemistry model with a total of nine gas species which includes dissociation of combustion products. A continually fed steel wire passes through the center of the nozzle, and melting occurs at a conical tip near the exit of the aircap. Wire melting is simulated computationally by injecting liquid steel particles into the flow field near the tip of the wire. Experimental particle velocity measurements during wire feed were also taken using a laser two-focus (L2F) velocimeter system. Flow fields inside and outside the aircap are presented, and particle velocity predictions are compared with experimental measurements outside of the aircap.

Cyclic loadings produce progressive damage that can ultimately result in wind turbine structural failure. There are many issues that must be dealt with in turning load measurements into estimates of component fatigue life. This paper deals with how the measured loads can be analyzed and processed to meet the needs of both fatigue life calculations and reliability estimates. It is recommended that moments of the distribution of rainfiow-range load amplitudes be calculated and used to characterize the fatigue loading. These moments reflect successively more detailed physical characteristics of the loading (mean, spread, tail behavior). Moments can be calculated from data samples and functional forms can befitted to wind conditions, such as wind speed and turbulence intensity, with standard regression techniques. Distributions of load amplitudes that accurately reflect the damaging potential of the loadings can be estimated from the moments at any wind condition of interest. Fatigue life can then be calculated from the estimated load distributions, and the overall, long-term, or design spectrum can be generated for any particular wind-speed distribution. Characterizing the uncertainty in the distribution of cyclic loads is facilitated by using a small set of descriptive statistics for which uncertainties can be estimated. The effects of loading parameter uncertainty can then be transferred to the fatigue life estimate and compared with other uncertainties, such as material durability. © 1998 by ASME.

High resolution, calibrated ion beam induced charge (IBIC) measurements from integrated circuit test structures have demonstrated that the measured charge collection in a device can exhibit significant change after only a few hundred ions/μm2 exposure, which may easily be exceeded in the initial targeting of a structure. For the purposes of determining a circuit's upset immunity or undamaged charge collection characteristics, such behaviour must be accounted for in evaluating IBIC measurements. This paper examines the influence of low level, ion induced damage on the magnitude of the measured lateral charge collection and also its resulting impact on IBIC image contrast. The lateral charge collection process is first characterised by calculating the amount of charge which diffuses to a collecting junction as a function of carrier diffusion length and the distance between the ion strike and junction edge. The effect of accumulated ion induced damage on lateral charge collection is then incorporated as a decrease in the resultant diffusion length. Calibrated IBIC measurements from the drain of a test FET structure are then explained using this predicted behaviour. © 1998 Elsevier Science B.V.

A methodology is presented that allows the derivation of low-truncation-error finite difference equations for photonics simulation. This methodology is applied to the case of wide-angle beam propagation in two dimensions, resulting in finite difference equations for both TE and TM polarization that are quasi-fourth-order accurate even in the presence of interfaces between dissimilar dielectrics. This accuracy is accomplished without an appreciable increase in numerical overhead and is concretely demonstrated for two test problems having known solutions. These finite difference equations facilitate an approach to the ideal of grid-independent computing and should allow the simulation of relevant photonics devices on personal computers.

Heavy Ion Backscattering Spectrometry (HIBS) is a new IBA tool for measuring extremely low levels of surface contamination on very pure substrates, such as Si wafers used in the manufacture of integrated circuits. HIBS derives its high sensitivity through the use of moderately low energy (∼100 keV) heavy ions (e.g. C12) to boost the RBS cross-section to levels approaching 1000 b, and by using specially designed time-of-flight (TOF) detectors which have been optimized to provide a large scattering solid angle with minimal kinematic broadening. A HIBS User Facility has been created which provides US industry, national laboratories, and universities with a place for conducting ultra-trace level surface contamination studies. A review of the HIBS technique is given and examples of using the facility to calibrate Total-Reflection X-ray Fluorescence Spectroscopy (TXRF) instruments and develop wafer cleaning processes are discussed. © 1998 Elsevier Science B.V.

Although they appear deceptively simple, batteries embody a complex set of interacting physical and chemical processes. While the discrete engineering characteristics of a battery, such as the physical dimensions of the individual components, are relatively straightforward to define explicitly, their myriad chemical and physical processes, including interactions, are much more difficult to accurately represent. For this reason, development of analytical models that can consistently predict the performance of a battery has only been partially successful, even though significant resources have been applied to this problem. As an alternative approach, we have begun development of non-phenomenological models for battery systems based on artificial neural networks. This paper describes initial feasibility studies as well as current models and makes comparisons between predicted and actual performance.

In this paper, a support and preload system is presented in which the frequencies and damping of the test article are affected by the stiffness and damping of the supporting structure. A dynamic model is derived for the support system that includes the damping as well as the mass and stiffness of the supports. The frequencies, damping, and mode shapes are compared with the experimentally determined parameters. It is shown that for a seemingly simple support system, deriving a predictive model is not a trivial task.

A method is presented for estimating uncertain or unknown parameters in a mathematical model using measurements of transient response. The method is based on a least squares formulation in which the differences between the model and test-based responses are minimized. An application of the method is presented for a nonlinear structural dynamic system. The method is also applied to a model of the Department of Energy armored tractor trailer. For the subject problem, the transient response was generated by driving the vehicle over a bump of prescribed shape and size. Results from the analysis and inspection of the test data revealed that a linear model of the vehicle's suspension is not adequate to accurately predict the response caused by the bump.

Recent advances in Vertical-Cavity Surface-Emitting Laser (VCSEL) technology that have led to higher efficiencies and lower thresholds have opened up a new realm of applications for these devices. In particular, phase-locked arrays of VCSELs1, previously thought to be impractical due to thermal considerations, now look extremely attractive as high-power and highbrightness sources. In addition, a new understanding of waveguiding in VCSELs2 has led to practical methods for designing phase-locked arrays employing either evansecent or leaky-mode (antiguided) coupling. The latter type of coupling is particularly attractive in light of previous calculations1 that predict especially strong mode discrimination against higher-order lateral modes. In this paper we report the first detailed simulation of leaky-mode coupling between two VCSEL pixels performed without the use of simplifying assumptions such as the effective index model. The results of this simulation are, however, found to be in good agreement with previously-developed simple theories3 of leaky-mode coupling.

This paper presents an overview of an explicit message-passing paradigm for a Eulerian finite volume method for modeling solid dynamics problems involving shock wave propagation, multiple materials, and large deformations. Three-dimensional simulations of high-velocity impact were conducted on the IBM SP2, the SGI Power Challenge Array, and the SGI Origin 2000. The scalability of the message-passing code on distributed-memory and symmetric multiprocessor architectures is presented and compared to the ideal linear performance.

We discuss revolutionary performance advances in selectively oxidized vertical-cavity surface emitting lasers (VCSELs), which have enabled low operating power laser diodes appropriate for aerospace applications. Incorporating buried oxide layers converted from AlGaAs layers within the laser cavity produces enhanced optical and electrical confinement enabling superior laser performance, such as high efficiency and modulation bandwidth. VCSELs are also shown to be viable over varied environmental conditions such as ambient temperature and ionized radiation. The development of novel VCSEL technologies for advanced system applications is also described. Two-dimensional individually addressable VCSEL arrays exhibit uniform threshold and operating characteristics. Bottom emitting 850 nm VCSEL arrays fabricated using wafer fusion are also reported.

LixMn2O4 materials are of considerable interest in battery research and development. The crystal structure of this material can significantly affect the electrochemical performance. The ability to monitor the changes of the crystal structure during use, that is during electrochemical cycling, would prove useful to verify these types of structural changes. We report in-situ XRD measurements of LiMn2O4 cathodes with the use of an electrochemical cell designed for in-situ X-ray analysis. Cells prepared using this cell design allow investigation of the changes in the LiMn2O4 structure during charge and discharge. We describe the variation in lattice parameters along the voltage plateaus and consider the structural changes in terms of the electrochemical results on each cell. Kinetic effects of LiMn2O4 phase changes are also addressed. Applications of the in-situ cell to other compounds such as LiCoO2 cathodes and carbon anodes are presented as well.

This paper discusses how phase plane analysis can be used to describe the overall behaviour of single and multiple autonomous robotic vehicles with finite state machine rules. The importance of this result is that we can begin to design provably asymptotically stable group behaviours from a set of simple control laws and appropriate switching points with decentralized variable structure control. The ability to prove asymptotically stable group behaviour is especially important for applications such as locating military targets or land mines.

We describe a class of microscale heaters fabricated with CMOS processes on silicon wafers. These heaters were designed to produce localized high temperatures above 400°C for test and sensor applications. The temperature levels produced for various input powers and the thermal profiles surrounding the heater for packaged and wafer-level heater structures were studied to guide the placement of microelectronics integrated with the heater structures on the same die. To show the performance of the design, we present resistance sensor measurements, IR temperature profiles, and results from a 3D thermal model of the die. This effort demonstrates that it is possible to successfully operate both a microscale heater and microcircuits on the same die.

The US Department of Energy has developed the Waste Isolation Pilot Plant (WIPP) in the bedded salt of southeastern New Mexico to demonstrate the safe disposal of radioactive transuranic wastes. Four vertical shafts provide access to the underground workings located at a depth of about 660 meters. These shafts connect the underground facility to the surface and potentially provide communication between lithologic units, so they will be sealed to limit both the release of hazardous waste from and fluid flow into the repository. The seal design must consider the potential for fluid flow through a disturbed rock zone (DRZ) that develops in the salt near the shafts. The DRZ, which forms initially during excavation and then evolves with time, is expected to have higher permeability than the native salt. The closure of the shaft openings (i.e., through salt creep) will compress the seals, thereby inducing a compressive back-stress on the DRZ. This back-stress is expected to arrest the evolution of the DRZ, and with time will promote healing of damage. This paper presents laboratory data from tertiary creep and hydrostatic compression tests designed to characterize damage evolution and healing in WIPP salt. Healing is quantified in terms of permanent reduction in permeability, and the data are used to estimate healing times based on considerations of first-order kinetics.

This paper reexamines orientations of shear bands (fault angles) predicted by a theory of shear localization as a bifurcation from homogeneous deformation. In contrast to the Coulomb prediction, which does not depend on deviatoric stress state, the angle between the band normal and the least (most compressive) principal stress increases as the deviatoric stress state varies from axisymmetric compression to axisymmetric extension. This variation is consistent with the data of Mogi (1967) on Dunham dolomite for axisymmetric compression, extension and biaxial compression, but the predicted angles are generally less than observed. This discrepancy may be due to anisotropy that develops due to crack growth in preferred orientations. Results from specialized constitutive relations for axisymmetric compression and plane strain that include this anisotropy indicate that it tends to increase the predicted angles. Measurements for a weak, porous sandstone (Castlegate) indicate that the band angle decreases with increasing inelastic compaction that accompanies increasing mean stress. This trend is consistent with the predictions of the theory but, for this rock, the observed angles are less than predicted.

The development of deep underground structures (e.g., shafts, mines, storage and disposal caverns) significantly alters the stress state in the rock near the structure or opening. The effect of such an opening is to concentrate the far-field stress near the free surface. For soft rock such as salt, the concentrating effect of the opening induces deviatoric stresses in the salt that may be large enough to initiate microcracks which then propagate with time. The volume of rock susceptible to damage by microfracturing is often referred to as the disturbed rock zone and, by its nature, is expected to exhibit high permeability relative to that of the native, far-field rock. This paper presents laboratory data that characterize microfracture-induced damage and the effect this damage has on permeability for bedded salt from the Waste Isolation Pilot Plant located in southeastern New Mexico. Damage is induced in the salt through a series of tertiary creep experiments and quantified in terms of dilatant volumetric strain. The permeability of damaged specimens is then measured using nitrogen gas as the permeant. The range in damage investigated included dilatant volumetric strains from less than 0.03 percent to nearly 4.0 percent. Permeability values corresponding to these damage levels ranged from 1 {times} 10{sup {minus}18} m{sup 2} to 1 {times} 10{sup {minus}12} m{sup 2}. Two simple models were fitted to the data for use in predicting permeability from dilatant volumetric strain.

This paper describes current research and development on a robotic visual servoing system for assembly of LIGA (lithography galvanoforming abforming) parts. The workcell consists of an AMTI robot, precision stage, long working distance microscope, and LIGA fabricated tweezers for picking up the parts. Fourier optics methods are used to generate synthetic microscope images from CAD drawings. These synthetic images are used off-line to test image processing routines under varying magnifications and depths of field. They also provide reference image features which are used to visually servo the part to the desired position.

An electrically injected coupled-resonator vertical-cavity laser (CRVCL) diode is described. The CRVCL consists of a lower 1-λ-thick active resonator containing three InGaAs quantum wells and a passive upper resonator composed of 1-λ-thick GaAs. Some of the characteristics arising from the cavity coupling, including methods for external modulation of the laser are demonstrated.

Microelectromechanical engines that convert the linear outputs from dual orthogonal electrostatic actuators to rotary motion were first developed in 1993. Referred to as microengines, these early devices demonstrated the potential of microelectromechanical technology, but, as expected from any first-of-its-kind device, were not yet optimized. Yield was relatively low, and the 10 micronewtons of force generated by the actuators was not always enough to ensure reliable operation. Since initial development, these engines have undergone a continuous series of significant improvements on three separate fronts: design, fabrication, and electrical activation. Although all three areas will be discussed, emphasis will be on aspects related to mechanical design and generation of the electrical waveforms used to drive these devices. Microtransmissions that dramatically increase torque will also be discussed. Electrostatically driven microengines can be operated at hundreds of thousands of revolutions per minute making large gear reduction ratios feasible; overall ratios of 3,000,000:1 have been successfully demonstrated. Today's microengines have evolved into high endurance (one test device has seen over 7,000,000,000 revolutions), high yield, robust devices that have become the primary actuation source for MicroElectroMechanical Systems (MEMS) at Sandia National Laboratories.

We have sputter-deposited 500-1200 Å thick WSi0.45 metallization onto n+ GaN (n≥1019 cm-3) doped either during MOCVD growth or by direct Si+ ion implantation (5×1015 cm-2, 100 keV) activated by RTA at 1100°C for 30 secs. In the epi samples Rc values of ∼10-14 ω cm2 were obtained, and were stable to ∼1000°C. The annealing treatments up to 600°C had little effect on the WSix/GaN interface, but the beta/-W2N phase formed between 700-800°C, concomitant with a strong reduction (approximately a factor of 2) in near-surface crystalline defects in the GaN. Spiking of the metallization down the threading and misfit dislocations was observed at 800°C, extending >5000 Å in some cases. This can create junction shorting in bipolar or thyristor devices, Rc values of <10-6 ωcm2 were obtained on the implanted samples for 950°C annealing, with values of after 1050°C anneals. The lower Rc values compared to epi samples appear to be a result of the higher peak doping achieved, ∼5×1020 cm-3. We observed wide spreads in Rc values over a wafer surface, with the values on 950°C annealed material ranging from 10-7 to 10-4 ω cm2. There appear to be highly nonuniform doping regions in the GaN, perhaps associated with the high defect density (1010 cm-2) in heteroepitaxial material, and this may contribute to the variations observed. We also believe that near-surface stoichiometry is variable in much of the GaN currently produced due to the relative ease of preferential N2 loss and the common use of HT containing growth (and cool-down) ambients. Finally the ohmic contact behavior of WSix on abrupt and graded composition InxAl1-xN layers has been studied as a function of growth temperature, InN mole fraction x=0.5-1) and post WSix deposition annealing treatment. Rc values in the range 10-3/-10sup-5/ ω cm2 are obtained for auto-doped n+ alloys, with the n-type background being little affected by growth conditions (n∼1020 cm-3). InN is the least temperature-stable alloy (les/700°C), and WSix contact morphology is found to depend strongly on the epi growth conditions.

The classification utility of a dual-antenna interferometric synthetic aperture radar (IFSAR) is explored by comparison of maximum likelihood classification results for synthetic aperture radar (SAR) intensity images and IFSAR intensity and coherence images. The addition of IFSAR coherence improves the overall classification accuracy for classes of trees, water, and fields. A threshold intensity-coherence classifier is also compared to the intensity-only classification results.

The constitutive model used to describe deformation of crushed salt is presented in this paper. Two mechanisms--dislocation creep and grain boundary diffusional pressure solutioning--are combined to form the basis for the constitutive model governing deformation of crushed salt. The constitutive model is generalized to represent three-dimensional states of stress. Recently completed creep consolidation tests are combined with an existing database that includes hydrostatic consolidation and shear consolidation tests conducted on Waste Isolation Pilot Plant (WIPP) and southeastern New Mexico salt to determine material parameters for the constitutive model. Nonlinear least-squares model fitting to data from shear consolidation tests and a combination of shear and hydrostatic tests produces two sets of material parameter values for the model. Changes in material parameter values from test group to test group indicate the empirical nature of the model but show significant improvement over earlier work. To demonstrate the predictive capability of the model, each parameter value set was used to predict each of the tests in the database. Based on fitting statistics and ability of the model to predict test data, the model appears to capture the creep consolidation behavior of crushed salt quite well.

A table top servohydraulic load frame equipped with a laser displacement measurement system was constructed for the mechanical characterization of LIGA fabricated electroforms. A drop-in tensile specimen geometry which includes a pattern to identify gauge length via laser scanning has proven to provide a convenient means to monitor and characterize mechanical property variations arising during processing. In addition to tensile properties, hardness and metallurgical data were obtained for nickel deposit specimens of current density varying between 20 and 80 mA/cm2 from a sulfamate based bath. Data from 80/20 nickel/iron deposits is also presented for comparison. As expected, substantial mechanical property differences from bulk metal properties are observed as well as a dependence of material strength on current density which is supported by grain size variation. While elastic modulus values of the nickel electrodeposit are near 160 GPa, yield stress values vary by over 60%. A strong orientation in the metal electrodeposits as well as variations in nucleating and growth morphology present a concern for anisotropic and geometry dependent mechanical properties within and between different LIGA components.

The first two truncation error terms resulting from finite differencing the convection terms in the two-dimensional Navier-Stokes equations are examined for the purpose of constructing two-dimensional grid generation schemes. These schemes are constructed such that the resulting grid distributions drive the error terms to zero. Two sets of equations result, one for each error term, that show promise in generating grids that provide more accurate flow solutions and possibly faster convergence. One set results in an algebraic scheme that drives the first truncation term to zero, and the other a hyperbolic scheme that drives the second term to zero. Also discussed is the possibility of using the schemes in sequentially constructing a grid in an iterative algorithm involving the flow solver. In essence, the process is envisioned to generate not only a flow field solution but the grid as well. Future work will include applications and extending the method to three dimensions.

Approximately 95% of the world's integrated chips are packaged using a hot, high pressure transfer molding process. The stress created by the flow of silica powder loaded epoxy can displace the fine bonding wires and can even distort the metalization patterns under the protective chip passivation layer [l, 2]. In this study we developed a technique to measure the mechanical stress over the surface of an integrated circuit during the molding process. A CMOS test chip with 25 diffused resistor stress sensors was applied to a commercial lead frame. Both compression and shear stresses were measured at all 25 locations on the surface of the chip every 50 milliseconds during molding. These measurements have a fine time and stress resolution which should allow comparison with computer simulation of the molding process, thus allowing optimization of both the manufacturing process and mold geometry.

Our research is focused on developing inorganic molecular sieve membranes for light gas separations such as hydrogen recovery and natural gas purification, and organic molecular separations, such as chiral enantiomers. We focus on zinc phosphates because of the ease in crystallization of new phases and the wide range of pore sizes and shapes obtained. With our hybrid systems of zinc phosphate crystalline phases templated by amine molecules, we are interested in better understanding the association of the template molecules to the inorganic phase, and how the organic transfers its size, shape, and (in some cases) chirality to the bulk. Furthermore, the new porous phases can also be synthesized as thin films on metal oxide substrates. These films allow us to make membranes from our organic/inorganic hybrid systems, suitable for diffusion experiments. Characterization techniques for both the bulk phases and the thin films include powder X-ray diffraction, TGA, Scanning Electron Micrograph (SEM) and Electron Dispersive Spectrometry (EDS).

The Southwest Surety Institute was formed in June, 1996 by Arizona State University (ASU), New Mexico Institute of Mining and Technology (NM Tech), New Mexico State University (NMSU), and Sandia National Laboratories (SNL) to provide new educational programs in Security Engineering. This is the first science-based program of its kind in the United States, directed at educating Security Engineers to help government and industry address their security needs. Current courses include security system design, evaluation, principles, and technology, the criminal justice system, and each member brings a unique educational capability to the institute. NMSU provides a security technology minor, merging programs in Criminal Justice and Electronics Technology. NM Tech has a formidable explosives testing and evaluation facility. ASU is developing a masters program in Security Engineering at their School of Technology located on a new campus in Mesa, Arizona. The Sandia National Laboratories security system design and evaluation process forms the basis for the security engineering curricula. In an effort to leverage the special capabilities of each university, distance education will be used to share courses among institute members and eventually with other sites across the country. The Institute will also pursue research and development funding in the areas of physical security information security, computer modeling and analysis, and counter-terrorist technology. Individual Institute members are currently working with sponsors from government and industry in areas such as counter-terrorism, microelectronics, banking, aviation, and sensor development.

We characterize in-situ the adhesion of surface micromachined polysilicon beams subject to controlled humidity ambients. Beams were freed by supercritical CO2 drying. Consistent adhesion results were obtained using a post-treatment in an oxygen plasma which rendered the microbeams uniformly hydrophilic. Individual beam deformations were measured by optical interferometry after equilibration at a given relative humidity (RH). Validation of each adhesion measurement was accomplished by comparing the deformations with elasticity theory. The data indicates that adhesion increases exponentially with RH from 30% to 95%, with values from 1 mJ/m2 to 50 mJ/m2. Using the Kelvin equation, we show that the data should be independent of RH if a smooth interface is considered. By modeling a rough interface consistent with atomic force microscopy (AFM) data, the exponential trend is satisfactorily explained.

Interferometric fringe maps are generated by accurately registering a pair of complex SAR images of the same scene imaged from two very similar geometries, and calculating the phase difference between the two images by averaging over a neighborhood of pixels at each spatial location. The phase difference (fringe) map resulting from this IFSAR operation is then unwrapped and used to calculate the height estimate of the imaged terrain. Although the method used to calculate interferometric fringe maps is well known, it is generally executed in a post-processing mode well after the image pairs have been collected. In that mode of operation, there is little concern about algorithm speed and the method is normally implemented on a single processor machine. This paper describes how the interferometric map generation is implemented on a distributed-memory parallel processing machine. This particular implementation is designed to operate on a 16 node Power-PC platform and to generate interferometric maps in near real-time. The implementation is able to accommodate large translational offsets, along with a slight amount of rotation which may exist between the interferometric pair of images. If the number of pixels in the IFSAR image is large enough, the implementation accomplishes nearly linear speed-up times with the addition of processors.

We describe two methods of combining two-pass RADARSAT interferometric phase maps with existing DTED (digital terrain elevation data) to produce improved terrain height estimates. The first is a least-squares estimation procedure that fits the unwrapped phase data to a phase map computed from the DTED. The second is a filtering technique that combines the interferometric height map with the DTED map based on spatial frequency content. Both methods preserve the high fidelity of the interferometric data.

In this paper we review the present status of z-pinches, and predict what the future holds. Although nobody can predict the future, the past 30 years have taught us some lessons that can be applied to the next 30 years.

Modern software development methods combined with key generalizations of standard computational algorithms enable the development of a new class of electromagnetic modeling tools. This paper describes current and anticipated capabilities of a frequency domain modeling code, EIGER, which has an extremely wide range of applicability. In addition, software implementation methods and high performance computing issues are discussed.

The Southwest Surety Institute was formed in June, 1996 by Arizona State University (ASU), New Mexico Institute of Mining and Technology (NM Tech), New Mexico State University (NMSU), and Sandia National Laboratories (SNL) to provide new educational programs in Security Engineering. This is the first science-based program of its kind in the United States, directed at educating Security Engineers to help government and industry address their security needs. Current courses include security system design, evaluation, principles, and technology, the criminal justice system, and each member brings a unique educational capability to the institute. NMSU provides a security technology minor, merging programs in Criminal Justice and Electronics Technology. NM Tech has a formidable explosives testing and evaluation facility. ASU is developing a masters program in Security Engineering at their School of Technology located on a new campus in Mesa, Arizona. The Sandia National Laboratories security system design and evaluation process forms the basis for the security engineering curricula. In an effort to leverage the special capabilities of each university, distance education will be used to share courses among institute members and eventually with other sites across the country. The Institute will also pursue research and development funding in the areas of physical security information security, computer modeling and analysis, and counter-terrorist technology. Individual Institute members are currently working with sponsors from government and industry in areas such as counter-terrorism, microelectronics, banking, aviation, and sensor development.

The implementation of a backscattered x-ray landmine detection system has been demonstrated in laboratories at both Sandia National Laboratories (SNL) and the University of Florida (UF). The next step was to evaluate the modality by assembling a system for field work. To assess the system's response to a variety of objects, buried plastic and metal antitank landmines, surface plastic antipersonnel landmines, and surface metal fragments were used as targets. The location of the test site was an unprepared field at SNL. The x-ray machine used for the field test system was an industrial x-ray machine which was operated at 150 kV and 5 mA and collimated to create a 2 cm diameter x-ray spot on the soil. The detectors used were two plastic scintillation detectors: one collimated (30 cm×30 cm active area) to respond primarily to photons that have undergone multiple collision and the other uncollimated (30 cm×7.6 cm active area) to respond primarily to photons that have had only one collision. To provide motion, the system was mounted on a gantry and rastered side-to-side using a computer-controlled stepper motor with a come-along providing the forward movement. Data generated from the detector responses were then analyzed to provide the images and locations of landmines. A new analysis method that increases resolution was used. Changing from the lab environment to the field did not decrease the system's ability to detect buried or obscured landmines. The addition of rain, blowing dust, rocky soil and native plant-life did not lower the system's resolution or contrast for the plastic or the metal landmines. Concepts for a civilian mine detection system based on this work using commercial off the shelf (COTS) equipment were developed.

A chemical solution powder synthesis technique has been developed that produces fine, uniform powders of lead magnesium niobate (PMN) with 60 to 80 nm crystallite size. The synthesis technique was based on the dissolution of lead acetate and alkoxide precursors in acetic acid followed by precipitation with oxalic acid/propanol solutions. Lead magnesium niobate ceramics fabricated from these chemically derived powders had smaller, more uniform grain size and higher dielectric constants than ceramics fabricated from mixed oxide powders that were processed under similar thermal conditions. Chem-prep PMN dielectrics with peak dielectric constants greater than 22,000 and polarizations in excess of 29 μC/cm2 were obtained for 1100 °C firing treatments. Substantial decreases in dielectric constant and polarization were measured for chemically prepared PMN ceramics fired at lower temperatures, consistent with previous work on mixed oxide materials.

The paper presents the history of safety devices used in nuclear weapons from the early days of separables to the latest advancements in MicroElectroMechanical Systems (MEMS). Although the paper focuses on devices, the principles of Enhanced Nuclear Detonation Safety implementation will also be presented.

Given a complete undirected graph with non-negative costs on the edges, the 2-Edge Connected Subgraph Problem consists in finding the minimum cost spanning 2-edge connected subgraph (where multiedges are allowed in the solution). A lower bound for the minimum cost 2-edge connected subgraph is obtained by solving the linear programming relaxation for this problem, which coincides with the subtour relaxation of the traveling salesman problem when the costs satisfy the triangle inequality. The simplest fractional solutions to the subtour relaxation are the (Formula presented)-integral solutions in which every edge variable has a value which is a multiple of (Formula presented). We show that the minimum cost of a 2-edge connected subgraph is at most four-thirds the cost of the minimum cost (Formula presented)-integral solution of the subtour relaxation. This supports the long-standing (Formula presented) Conjecture for the TSP, which states that there is a Hamilton cycle which is within (Formula presented) times the cost of the optimal subtour relaxation solution when the costs satisfy the triangle inequality.

The need for advanced (electronic) ceramic components with smaller size, greater functionality, and enhanced reliability requires the ability to integrate electronic ceramics in complex 3-D architectures. However, traditional tape casting and screen printing approaches are poorly suited to the requirements of rapid prototyping and smalI-lot manufacturing. To address this need, we are developing a direct-write approach for fabricating highly integrated, multilayer components using a micropen to deposit slurries in precise patterns. This approach provides the ability to fabricate multifunctional, multimaterial integrated ceramic components (MMICCs) in an agile and rapid way, and has been used to make integrated passive devices such RC filters, inductors, and voltage transformers.

All systems, regardless of how carefully they have been constructed, suffer failures. This paper focuses on developing a formal understanding of failure with respect to system implementations. Furthermore, we would like the system design process to be able to leverage off of this understanding. It is important to deal with failures in a system context, rather than a priori limiting the solution to a particular technology, such as software alone. Our approach is limited to the class of systems that can be modeled by hybrid finite state machines (HFSMs) as described V.L. Winter. The purpose of this paper is to lay out a process, or framework, that can aid in identification and characterization of techniques for dealing with the different types of system threats. This framework leads naturally to a taxonomy of technologies and strategies for dealing with the various types of threats. In this process technologies are used to identify a priority list of technical capabilities for dealing with threats. The technologies are prioritized according to their analyzability and predictability. Strategies are then used to identify specific implementations that are best suited to dealing with the threat.

High-energy pulsed-power devices routinely access field strengths above those at which broad-area, cathode-initiated, high-voltage vacuum-breakdown occur (> le7 - 3e7 V/m). Examples include magnetically-insulated-transmission-lines and current convolutes, high-current-density electron and ion diodes, high-power microwave devices, and cavities and other structures for electrostatic and RF accelerators. Energy deposited in anode surfaces may exceed anode plasma thermal-desorption creation thresholds on the time-scale of the pulse. Stimulated desorption by electron or photon bombardment can also lead to plasma formation on electrode or insulator surfaces. Device performance is limited above these thresholds, particularly in pulselength and energy, by the formation and expansion of plasmas formed primarily from electrode contaminants. Insitu conditioning techniques to modify and eliminate the contaminants through multiple high-voltage pulses, low base pressures, RF discharge cleaning, heating, surface coatings, and ion- and electron-beam surface treatment allow access to new regimes of performance through control of plasma formation and modification of the plasma properties. Experimental and theoretical progress from a variety of devices and small scale experiments with a variety of treatment methods will be reviewed and recommendations given for future work.

The von Mises stress is often used as the metric for evaluating design margins, particularly for structures made of ductile materials. For deterministic loads, both static and dynamic, the calculation of von Mises stress is straightforward, as is the resulting calculation of reliability. For loads modeled as random processes, the task is different; the response to such loads is itself a random process and its properties must be determined in terms of those of both the loads and the system. This has been done in the past by Monte Carlo sampling of numerical realizations that reproduce the second order statistics of the problem. Here, we present a method that provides analytic expressions for the probability distributions of von Mises stress which can be evaluated efficiently and with good precision numerically. Further, this new approach has the important advantage of

The rapidly increasing use of composites on commercial airplanes coupled with the potential for economic savings associated with their use in aircraft structures means that the demand for composite materials technology will continue to increase. Inspecting these composite structures is a critical element in assuring their continued airworthiness. The FAA's Airworthiness Assurance NDI Validation Center, in conjunction with the Commercial Aircraft Composite Repair Committee, is developing a set of composite reference standards to be used in NDT equipment calibration for accomplishment of damage assessment and post-repair inspection of all commercial aircraft composites. In this program, a series of NDI tests on a matrix of composite aircraft structures and prototype reference standards were completed in order to minimize the number of standards needed to carry out composite inspections on aircraft. Two tasks, related to composite laminates and non-metallic composite honeycomb configurations, were addressed. A suite of 64 honeycomb panels, representing the bounding conditions of honeycomb construction on aircraft, were inspected using a wide array of NDI techniques. An analysis of the resulting data determined the variables that play a key role in setting up NDT equipment. This has resulted in a prototype set of minimum honeycomb reference standards that include these key variables. A sequence of subsequent tests determined that this minimum honeycomb reference standard set is able to fully support inspections over the full range of honeycomb construction scenarios. Current tasks are aimed at optimizing the methods used to engineer realistic flaws into the specimens. In the solid composite laminate arena, we have identified what appears to be an excellent candidate, G11 Phenolic, as a generic solid laminate reference standard material. Testing to date has determined matches in key velocity and acoustic impedance properties, as well as, low attenuation relative to carbon laminates. Furthermore, comparisons of resonance testing response curves from the G11 Phenolic prototype standard was very similar to the resonance response curves measured on the existing carbon and fiberglass laminates. NDI data shows that this material should work for both pulse-echo (velocity-based) and resonance (acoustic impedance-based) inspections. Additional testing and industry review activities are underway to complete the validation of this material. © 1998 Society of Automotive Engineers, Inc.

Geologic, and historical well failure, production, and injection data were analyzed to guide development of three-dimensional geomechanical models of the Belridge Diatomite Field, California. Time-dependent reservoir pressure fields that were calculated from three-dimensional finite difference reservoir simulations were input into three-dimensional nonlinear finite element geomechanical simulations. In general, the simulations suggest the three types of casing damage observed, and show that although water injection has mitigated surface subsidence, it can, under some circumstances, increase the lateral gradients in effect stress, that in turn can accelerate subsurface horizontal motions.

The second operational test of the String Thermionic Assembly Research Testbed -- Re-START -- was carried out from June 9 to June 14, 1997. This test series was designed to help qualify and validate the designs and test methods proposed for the Integrated Solar Upper Stage (ISUS) power converters for use during critical evaluations of the complete ISUS bimodal system during the Engine Ground Demonstration (EGD). The test article consisted of eight ISUS prototype thermionic converter diodes electrically connected in series.

Several metal macrocyclic complexes were synthesized for use as catalysts in fuel cells. An initial evaluation of their ability to catalyze the fuel cell reactions were completed. Based on this initial evaluation, one metal macrocyclic catalyst was selected and long-term stability testing in a fuel cell was initiated. The fuel cell employing this catalyst was operated continuously for one year with little signs of catalyst degradation. The effect of synthetic reformates on the performance of the catalyst in the fuel cell environment also demonstrated high tolerance of this catalyst for common contaminants and poisons.

It is shown that dissolutive wetting initially yields a metastable equilibrium. A compact model for the kinetics of approach to this metastable state is described. The technique for constructing these kinetics stems from the early work of Onsager and begins with a relationship for the entropy production. From this, a coupled set of nonlinear, ordinary differential equations can be written directly. The equations are solved numerically for the wetted area and compared with experimental data. The model captures many of the subtle complexities of dissolutive wetting such as multiple metastable states. Sessile drop experiments involving a variety of Bi-Sn alloys on solid Bi substrates were performed. Substrates prepared from small and large-grained polycrystals and single crystals were used to measure equilibrium and metastable contact angles and estimate the surface tension and equilibrium contact angle of the solid-liquid interface. The substrates were also used to investigate the coupling of the dissolution and wetting processes and to investigate the effect of substrate grain size on wetting. It was determined that the equilibrium wetting geometry is independent of linear scale and that grain size has little influence on wetting or dissolution in the Bi-Sn system. To investigate the atomic behavior of liquids at interfaces during wetting, the authors simulated wetting in the Ag-Cu system using molecular dynamics with atomic potentials and observed both atomic dynamics and structural correlations of the liquid-solid interface. The authors found that spreading is prompted by interactions between the liquid and the substrate surface that cause the liquid layer in contact with the substrate to take on some of the symmetry of the substrate surface and result in the formation of a liquid monolayer that extends beyond the major part of the liquid droplet.

This report summarizes the development of in situ optical photoreflectance as a tool for measuring impurity concentrations in compound semiconductors. The authors have successfully explored the use of photoreflectance as an in situ tool for measuring n-type doping levels in metal-organic chemical vapor deposition (MOCVD) grown GaAs materials. The technique measures phase and frequency shifts in Franz-Keldysh oscillations measured on uniformly doped thin films. Doping concentrations from 5 {times} 10{sup 16} to 1 {times} 10{sup 18} can be measured at temperatures below 130 C. A method has been developed to include photoreflectance as the last step in the pre-growth in situ calibration procedure for MOCVD thin film structures. This combined capability now enables one to rapidly and accurately determine growth rates, chemical composition, and doping levels necessary to generate a recipe to fabricate complex optoelectronic compound semiconductor devices.

The W88 Integrated Circuit Shelf Life Program was created to monitor the long term performance, reliability characteristics, and technological status of representative WR ICs manufactured by the Allied Signal Albuquerque Microelectronics Operation (AMO) and by Harris Semiconductor Custom Integrated Circuits Division. Six types of ICs were used. A total of 272 ICs entered two storage temperature environments. Electrical testing and destructive physical analysis were completed in 1995. During each year of the program, the ICs were electrically tested and samples were selected for destructive physical analysis (DPA). ICs that failed electrical tests or DPA criteria were analyzed. Fifteen electrical failures occurred, with two dominant failure modes: electrical overstress (EOS) damage involving the production test programs and electrostatic discharge (ESD) damage during analysis. Because of the extensive handling required during multi-year programs like this, it is not unusual for EOS and ESD failures to occur even though handling and testing precautions are taken. The clustering of the electrical test failures in a small subset of the test operations supports the conclusion that the test operation itself was responsible for many of the failures and is suspected to be responsible for the others. Analysis of the electrical data for the good ICs found no significant degradation trends caused by the storage environments. Forty-six ICs were selected for DPA with findings primarily in two areas: wire bonding and die processing. The wire bonding and die processing findings are not surprising since these technology conditions had been documented during manufacturing and were determined to present acceptable risk. The current reliability assessment of the W88 stockpile assemblies employing these and related ICs is reinforced by the results of this shelf life program. Data from this program will aid future investigation of 4/3 micron or MNOS IC technology failure modes.

New techniques have been recently developed that allow unstructured, free meshes to be embedded into standard 3-dimensional, rectilinear, finite-difference time-domain grids. The resulting hybrid-grid modeling capability allows the higher resolution and fidelity of modeling afforded by free meshes to be combined with the simplicity and efficiency of rectilinear techniques. Integration of these new methods into the full-featured, general-purpose QUICKSILVER electromagnetic, Particle-In-Cell (PIC) code provides new modeling capability for a wide variety of electromagnetic and plasma physics problems. To completely exploit the integration of this technology into QUICKSILVER for applications requiring the self-consistent treatment of charged particles, this project has extended existing PIC methods for operation on these hybrid unstructured/rectilinear meshes. Several technical issues had to be addressed in order to accomplish this goal, including the location of particles on the unstructured mesh, adequate conservation of charge, and the proper handling of particles in the transition region between structured and unstructured portions of the hybrid grid.

Modifications to the constitutive model used to describe the deformation of crushed salt are presented in this report. Two mechanisms--dislocation creep and grain boundary diffusional pressure solutioning--defined previously but used separately are combined to form the basis for the constitutive model governing the deformation of crushed salt. The constitutive model is generalized to represent three-dimensional states of stress. New creep consolidation tests are combined with an existing database that includes hydrostatic consolidation and shear consolidation tests conducted on Waste Isolation Pilot Plant and southeastern New Mexico salt to determine material parameters for the constitutive model. Nonlinear least-squares model fitting to data from the shear consolidation tests and a combination of the shear and hydrostatic consolidation tests produced two sets of material parameter values for the model. The change in material parameter values from test group to test group indicates the empirical nature of the model but demonstrates improvement over earlier work with the previous models. Key improvements are the ability to capture lateral strain reversal and better resolve parameter values. To demonstrate the predictive capability of the model, each parameter value set was used to predict each of the tests in the database. Based on the fitting statistics and the ability of the model to predict the test data, the model appears to capture the creep consolidation behavior of crushed salt quite well.

WIPP Salado Hydrology Program Data Report {number_sign}3 presents hydrologic data collected during permeability testing, coupled permeability and hydrofracture testing, and gas-threshold-pressure testing of the Salado Formation performed from November 1991 through October 1995. Fluid-pressure monitoring data representing August 1989 through May 1995 are also included. The report presents data from the drilling and testing of three boreholes associated with the permeability testing program, nine boreholes associated with the coupled permeability and hydrofracture testing program, and three boreholes associated with the gas-threshold-pressure testing program. The purpose of the permeability testing program was to provide data with which to interpret the disturbed and undisturbed permeability and pore pressure characteristics of the different Salado Formation lithologies. The purpose of the coupled permeability and hydrofracture testing program was to provide data with which to characterize the occurrence, propagation, and direction of pressure induced fractures in the Salado Formation lithologies, especially MB139. The purpose of the gas-threshold-pressure testing program was to provide data with which to characterize the conditions under which pressurized gas displaces fluid in the brine-saturated Salado Formation lithologies. All of the holes were drilled from the WIPP underground facility 655 m below ground surface in the Salado Formation.

This report describes the methodology for using a genetic programming model to develop tracking behaviors for autonomous, microscale robotic vehicles. The use of such vehicles for surveillance and detection operations has become increasingly important in defense and humanitarian applications. Through an evolutionary process similar to that found in nature, the genetic programming model generates a computer program that when downloaded onto a robotic vehicle`s on-board computer will guide the robot to successfully accomplish its task. Simulations of multiple robots engaged in problem-solving tasks have demonstrated cooperative behaviors. This report also discusses the behavior model produced by genetic programming and presents some results achieved during the study.

In this report the analysis of a micro-scale pump is described. This micro-pump uses active control to produce a distributed body force in a fluid micro-channel. The desired effect of this body force is to drive fluid through the channel. Limitations, assumptions, and design parameters are discussed. The mathematical analysis of pump dynamics is explained in detail. A perturbation analysis is used on the equations of mass, momentum and state to produce equations of motion for first and second order effects. The first order effects are described by linear wave motion in the fluid and are found by using integral equation methods. The second order effects are driven by body forces resulting from first order effects. Thus, by controlling the production of wave motion in the channel, second order excitation can also be controlled. This report is all theory and therefore needs experimental validation. Although many of the assumptions used in this report have been used elsewhere in the literature and have been found to be sufficient, there are many aspects of the problem which have been left unresolved. In particular, flow separation in the fluid channel is a critical problem. If the fluid does not separate, pumping will occur through the channel, however, if internal or external forces are not sufficient to stop separation, this type of pump will not function.

In this paper, we will discuss the use of z-pinch sources for shock wave studies at multi-Mbar pressures. Experimental plans to use the technique for absolute shock Hugoniot measurements are discussed. Recent developments have demonstrated the use of pulsed power techniques for producing intense radiation sources (Z pinches) for driving planar shock waves in samples with spatial dimensions significantly larger than possible with other radiation sources. Initial indications are that using Z pinch sources for producing Planckian radiation sources in secondary hohlraums can be used to drive shock waves in samples with diameters to a few millimeters and thickness approaching one millimeter in thickness. These dimensions provides the opportunity to measure both shock velocity and the particle velocity behind the shock front with accuracy comparable to that obtained with gun launchers. In addition, the peak hohlraum temperatures of nearly 150 eV that are now possible with Z pinch sources result in shock wave pressures approaching 45 Mbar in high impedance materials such as tungsten and 10-15 Mbar in low impedance materials such as aluminum and plastics. In this paper, we discuss the use of Z pinch sources for making accurate absolute EOS measurements in the megabar pressure range.

We have developed a method for encoding phase and amplitude in microscopic computer-generated holograms (microtags) for security applications. Eight-by-eight-cell and 12 x 12-cell phase-only and phase-and-amplitude microtag designs has been exposed in photoresist using the extreme-ultraviolet (13.4 nm) lithography (EUVL) tool developed at Sandia National Laboratories. Using EUVL, we have also fabricated microtags consisting of 150-nm lines arranged to form 300-nm-period gratings. The microtags described in this report were designed for readout at 632.8 nm and 442 nm. The smallest microtag measures 56 {mu}m x 80 {mu}m when viewed at normal incidence. The largest microtag measures 80 by 160 microns and contains features 0.2 {mu}m wide. The microtag design process uses a modified iterative Fourier-transform algorithm to create either phase-only or phase-and-amplitude microtags. We also report on a simple and compact readout system for recording the diffraction pattern formed by a microtag. The measured diffraction patterns agree very well with predictions. We present the results of a rigorous coupled-wave analysis (RCWA) of microtags. Microtags are CD modeled as consisting of sub-wavelength gratings of a trapezoidal profile. Transverse-electric (TE) and TM readout polarizations are modeled. The objective of our analysis is the determination of optimal microtag-grating design parameter values and tolerances on those parameters. The parameters are grating wall-slope angle, grating duty cycle, grating depth, and metal-coating thickness. Optimal microtag-grating parameter values result in maximum diffraction efficiency. Maximum diffraction efficiency is calculated at 16% for microtag gratings in air and 12% for microtag gratings underneath a protective dielectric coating, within fabrication constraints. TM-microtag gratings. Finally, we suggest several additional microtag concepts, such as two-dimensional microtags and pixel-code microtags.

One of the most formidable intelligence challenges existing in the non-proliferation community is the detection of buried targets. The physical parameter that all buried targets share, whether the target is buried armaments, a tunnel or a bunker, is mass. In the case of buried armaments, there is an excess mass (higher density) compared to the surrounding area; for a tunnel or bunker, the mass is missing. In either case, this difference in mass generates a distinct gravitational signature. The Superconducting Gravity Gradiometer project at Sandia worked toward developing an airborne device for the detection of these underground structures.

Monuments, buildings, and works of art constructed of carbonate-based stone (calcite, e.g., limestone and marble) are subject to deterioration resulting from the effects of environmental exposure, granular disintegration, freeze/thaw cycles, and salt recrystallization. This damage can potentially be reversed by the use of mineral-specific chemical passivants and consolidants that prevent hydrolytic attack and mechanical weakening. The treatment strategy combined the use of calcite coupling molecules to passivate the surfaces against new weathering with alkoxysilane strengthening or consolidating layers to arrest physical deterioration. The authors report on the effectiveness of passivating agents designed through a combined approach of modeling their adhesive and passivating properties using computations at the molecular scale and testing those properties using simulated leaching tests, microscopic evaluation, and characterization of mechanical strength. The experimental results indicate that there may be a threshold binding energy for the passivant above which the dissolution rate of calcite is actually enhanced. Passivant/consolidant treatments were identified which showed substantial reductions in the leach rate of calcite exposed to simulated acid rain conditions.

The fields of tolerancing and assembly analysis have depended for decades on ad hoc, shop floor methods. This causes serious problems when subjected toleranced designs to automated, analytical methods. This project attempted to further the formalization and mathematization of tolerancing by extending the concept of the Maximum Material Part. A software system was envisioned that would guide designers in the use of appropriate tolerance specifications and then create software models of Maximum Material Parts from the toleranced nominal parts.