Though the Global Positioning System has revolutionized navigation in the modern age, it is limited in its capability for some applications because an unobstructed line of sight to a minimum of four satellites is required. One way of augmenting the system in small areas is by employing pseudolites to broadcast additional signals that can be used to improve the user's position solution. At the Navigation Systems Testing Laboratory (NSTL) at NASA's Johnson Space Center in Houston, TX, research has been underway on the use of pseudolites to perform precision relative navigation. Based on the findings of previous research done at the NSTL, the method used to process the pseudolite measurements is an extended Kalman filter of the double differenced carrier phase measurements. By employing simulations of the system, as well as processing previously collected data in a real time manner, sub-meter tracking of a moving receiver with carrier phase measurements in the extended Kalman filter appears to be possible.
The ASCI supercomputing program is broadly defined as running physics simulations on progressively more powerful digital computers. What happens if we extrapolate the computer technology to its end? We have developed a model for key ASCI computations running on a hypothetical computer whose technology is parameterized in ways that account for advancing technology. This model includes technology information such as Moore's Law for transistor scaling and developments in cooling technology. The model also includes limits imposed by laws of physics, such as thermodynamic limits on power dissipation, limits on cooling, and the limitation of signal propagation velocity to the speed of light. We apply this model and show that ASCI computations will advance smoothly for another 10-20 years to an 'end game' defined by thermodynamic limits and the speed of light. Performance levels at the end game will vary greatly by specific problem, but will be in the Exaflops to Zetaflops range for currently anticipated problems. We have also found an architecture that would be within a constant factor of giving optimal performance at the end game. This architecture is an evolutionary derivative of the mesh-connected microprocessor (such as ASCI Red Storm or IBM Blue Gene/L). We provide designs for the necessary enhancement to microprocessor functionality and the power-efficiency of both the processor and memory system. The technology we develop in the foregoing provides a 'perfect' computer model with which we can rate the quality of realizable computer designs, both in this writing and as a way of designing future computers. This report focuses on classical computers based on irreversible digital logic, and more specifically on algorithms that simulate space computing, irreversible logic, analog computers, and other ways to address stockpile stewardship that are outside the scope of this report.
This report summarizes research advances pursued with award funding issued by the DOE to Drexel University through the Presidential Early Career Award (PECASE) program. Professor Rich Cairncross was the recipient of this award in 1997. With it he pursued two related research topics under Sandia's guidance that address the outstanding issue of fluid-structural interactions of liquids with deformable solid materials, focusing mainly on the ubiquitous dynamic wetting problem. The project focus in the first four years was aimed at deriving a predictive numerical modeling approach for the motion of the dynamic contact line on a deformable substrate. A formulation of physical model equations was derived in the context of the Galerkin finite element method in an arbitrary Lagrangian/Eulerian (ALE) frame of reference. The formulation was successfully integrated in Sandia's Goma finite element code and tested on several technologically important thin-film coating problems. The model equations, the finite-element implementation, and results from several applications are given in this report. In the last year of the five-year project the same physical concepts were extended towards the problem of capillary imbibition in deformable porous media. A synopsis of this preliminary modeling and experimental effort is also discussed.
Science historian James Burke is well known for his stories about how technological innovations are intertwined and embedded in the culture of the time, for example, how the steam engine led to safety matches, imitation diamonds, and the landing on the moon.1 A lesson commonly drawn from his stories is that the path of science and technology (S&T) is nonlinear and unpredictable. Viewed another way, the lesson is that the solution to one problem can lead to solutions to other problems that are not obviously linked in advance, i.e., there is a ripple effect. The motto for Sandia's approach to research and development (R&D) is 'Science with the mission in mind.' In our view, our missions contain the problems that inspire our R&D, and the resulting solutions almost always have multiple benefits. As discussed below, Sandia's Laboratory Directed Research and Development (LDRD) Program is structured to bring problems relevant to our missions to the attention of researchers. LDRD projects are then selected on the basis of their programmatic merit as well as their technical merit. Considerable effort is made to communicate between investment areas to create the ripple effect. In recent years, attention to the ripple effect and to the performance of the LDRD Program, in general, has increased. Inside Sandia, as it is the sole source of discretionary research funding, LDRD funding is recognized as being the most precious of research dollars. Hence, there is great interest in maximizing its impact, especially through the ripple effect. Outside Sandia, there is increased scrutiny of the program's performance to be sure that it is not a 'sandbox' in which researchers play without relevance to national security needs. Let us therefore address the performance of the LDRD Program in fiscal year 2003 and then show how it is designed to maximize impact.
The ASCI Grid Services (initially called Distributed Resource Management) project was started under DisCom{sup 2} when distant and distributed computing was identified as a technology critical to the success of the ASCI Program. The goals of the Grid Services project has and continues to be to provide easy, consistent access to all the ASCI hardware and software resources across the nuclear weapons complex using computational grid technologies, increase the usability of ASCI hardware and software resources by providing interfaces for resource monitoring, job submission, job monitoring, and job control, and enable the effective use of high-end computing capability through complex-wide resource scheduling and brokering. In order to increase acceptance of the new technology, the goal included providing these services in both the unclassified as well as the classified user's environment. This paper summarizes the many accomplishments and lessons learned over approximately five years of the ASCI Grid Services Project. It also provides suggestions on how to renew/restart the effort for grid services capability when the situation is right for that need.
To establish mechanical material properties of cellular concrete mixes, a series of quasi-static, compression and tension tests have been completed. This report summarizes the test methods, set-up, relevant observations, and results from the constitutive experimental efforts. Results from the uniaxial and triaxial compression tests established failure criteria for the cellular concrete in terms of stress invariants I{sub 1} and J{sub 2}. {radical}J{sub 2} (MPa) = 297.2 - 278.7 exp{sup -0.000455 I}{sub 1}{sup (MPa)} for the 90-pcf concrete {radical}J{sub 2} (MPa) = 211.4 - 204.2 exp {sup -0.000628 I}{sub 1}{sup (MPa)} for the 60-pcf concrete
For many decades, engineers and scientists have studied the effects of high power microwaves (HPM) on electronics. These studies usually focus on means of delivering energy to upset electronic equipment and ways to protect equipment from HPM. The motivation for these studies is to develop the knowledge necessary either to cause disruption or to protect electronics from disruption. Since electronic circuits must absorb sufficient energy to fail and the source used to deliver this energy is far away from the electronic circuit, the source must emit a large quantity of energy. In free space, for example, as the distance between the source and the target increases, the source energy must increase by the square of distance. The HPM community has dedicated substantial resources to the development of higher energy sources as a result. Recently, members of the HPM community suggested a new disruption mechanism that could potentially cause system disruptions at much lower energy levels. The new mechanism, based on nonlinear dynamics, requires an expanded theory of circuit operation. This report summarizes an investigation of electronic circuit nonlinear behavior as it applies to inductor-resistor-diode circuits (known as the Linsay circuit) and phased-locked-loops. With the improvement in computing power and the need to model circuit behavior with greater precision, the nonlinear effects of circuit has become very important. In addition, every integrated circuit has as part of its design a protective circuit. These protective circuits use some variation of semiconductor junctions that can interact with parasitic components, present in every real system. Hence, the protective circuit can behave as a Linsay circuit. Although the nonlinear behavior is understandable, it is difficult to model accurately. Many researchers have used classical diode models successfully to show nonlinear effects within predicted regions of operation. However, these models do not accurately predict measured results. This study shows that models based on SPICE, although they exhibit chaotic behavior, do not properly reproduce circuit behavior without modifying diode parameters. This report describes the models and considerations used to model circuit behavior in the nonlinear range of operation. Further, it describes how a modified SPICE diode model improves the simulation results. We also studied the nonlinear behavior of a phased-locked-loop. Phased-locked loops are fundamental building block to many major systems (aileron, seeker heads, etc). We showed that an injected RF signal could drive the phased-locked-loop into chaos. During these chaotic episodes, the frequency of the phased-locked-loop takes excursion outside its normal range of operation. In addition to these excursions, the phased-locked-loop and the system it is controlling requires some time to get back into normal operation. The phased-locked-loop only needs to be upset enough long enough to keep it off balance.
A variety of multivariate calibration algorithms for quantitative spectral analyses were investigated and compared, and new algorithms were developed in the course of this Laboratory Directed Research and Development project. We were able to demonstrate the ability of the hybrid classical least squares/partial least squares (CLSIPLS) calibration algorithms to maintain calibrations in the presence of spectrometer drift and to transfer calibrations between spectrometers from the same or different manufacturers. These methods were found to be as good or better in prediction ability as the commonly used partial least squares (PLS) method. We also present the theory for an entirely new class of algorithms labeled augmented classical least squares (ACLS) methods. New factor selection methods are developed and described for the ACLS algorithms. These factor selection methods are demonstrated using near-infrared spectra collected from a system of dilute aqueous solutions. The ACLS algorithm is also shown to provide improved ease of use and better prediction ability than PLS when transferring calibrations between near-infrared calibrations from the same manufacturer. Finally, simulations incorporating either ideal or realistic errors in the spectra were used to compare the prediction abilities of the new ACLS algorithm with that of PLS. We found that in the presence of realistic errors with non-uniform spectral error variance across spectral channels or with spectral errors correlated between frequency channels, ACLS methods generally out-performed the more commonly used PLS method. These results demonstrate the need for realistic error structure in simulations when the prediction abilities of various algorithms are compared. The combination of equal or superior prediction ability and the ease of use of the ACLS algorithms make the new ACLS methods the preferred algorithms to use for multivariate spectral calibrations.
The goal of this Laboratory Directed Research & Development (LDRD) effort was to design, synthesize, and evaluate organic-inorganic nanocomposite membranes for solubility-based separations, such as the removal of higher hydrocarbons from air streams, using experiment and theory. We synthesized membranes by depositing alkylchlorosilanes on the nanoporous surfaces of alumina substrates, using techniques from the self-assembled monolayer literature to control the microstructure. We measured the permeability of these membranes to different gas species, in order to evaluate their performance in solubility-based separations. Membrane design goals were met by manipulating the pore size, alkyl group size, and alkyl surface density. We employed molecular dynamics simulation to gain further understanding of the relationship between membrane microstructure and separation performance.
The Maximum Permissible Exposure (MPE) is central to laser hazard analysis and is in general a function of the radiant wavelength. The selection of a laser for a particular application may allow for flexibility in the selection of the radiant wavelength. This flexibility would allow the selection of a particular laser based on the MPE and the hazards associated with that radiant wavelength. The Calculations of the MPEs for various laser wavelength ranges are presented. Techniques for determining eye safe viewing distances for both aided and unaided viewing and the determination of flight hazard distances are presented as well.
A key factor in our ability to produce and predict the stability of metal-based macro- to nano-scale structures and devices is a fundamental understanding of the localized nature of corrosion. Corrosion processes where physical dimensions become critical in the degradation process include localized corrosion initiation in passivated metals, microgalvanic interactions in metal alloys, and localized corrosion in structurally complex materials like nanocrystalline metal films under atmospheric and inundated conditions. This project focuses on two areas of corrosion science where a fundamental understanding of processes occurring at critical dimensions is not currently available. Sandia will study the critical length scales necessary for passive film breakdown in the inundated aluminum (Al) system and the chemical processes and transport in ultra-thin water films relevant to the atmospheric corrosion of nanocrystalline tungsten (W) films. Techniques are required that provide spatial information without significantly perturbing or masking the underlying relationships. Al passive film breakdown is governed by the relationship between area of the film sampled and its defect structure. We will combine low current measurements with microelectrodes to study the size scale required to observe a single initiation event and record electrochemical breakdown events. The resulting quantitative measure of stability will be correlated with metal grain size, secondary phase size and distribution to understand which metal properties control stability at the macro- and nano-scale. Mechanisms of atmospheric corrosion on W are dependent on the physical dimensions and continuity of adsorbed water layers as well as the chemical reactions that take place in this layer. We will combine electrochemical and scanning probe microscopic techniques to monitor the chemistry and resulting material transport in these thin surface layers. A description of the length scales responsible for driving the corrosion of the nanocrystalline metal films will be developed. The techniques developed and information derived from this work will be used to understand and predict degradation processes in microelectronic and microsystem devices critical to Sandia's mission.
Chemical disinfection and inactivation of viruses is largely understudied, but is very important especially in the case of highly infectious viruses. The purpose of this LDRD was to determine the efficacy of the Sandia National Laboratories developed decontamination formulations against Bovine Coronavirus (BCV) as a surrogate for the coronavirus that causes Severe Acute Respiratory Syndrome (SARS) in humans. The outbreak of SARS in late 2002 resulted from a highly infectious virus that was able to survive and remain infectious for extended periods. For this study, preliminary testing with Escherichia coli MS-2 (MS-2) and Escherichia coli T4 (T4) bacteriophages was conducted to develop virucidal methodology for verifying the inactivation after treatment with the test formulations following AOAC germicidal methodologies. After the determination of various experimental parameters (i.e. exposure, concentration) of the formulations, final testing was conducted on BCV. All experiments were conducted with various organic challenges (horse serum, bovine feces, compost) for results that more accurately represent field use condition. The MS-2 and T4 were slightly more resistant than BCV and required a 2 minute exposure while BCV was completely inactivated after a 1 minute exposure. These results were also consistent for the testing conducted in the presence of the various organic challenges indicating that the test formulations are highly effective for real world application.
Microelectromechanical systems (MEMS) comprise a new class of devices that include various forms of sensors and actuators. Recent studies have shown that microscale cantilever structures are able to detect a wide range of chemicals, biomolecules or even single bacterial cells. In this approach, cantilever deflection replaces optical fluorescence detection thereby eliminating complex chemical tagging steps that are difficult to achieve with chip-based architectures. A key challenge to utilizing this new detection scheme is the incorporation of functionalized MEMS structures within complex microfluidic channel architectures. The ability to accomplish this integration is currently limited by the processing approaches used to seal lids on pre-etched microfluidic channels. This report describes Sandia's first construction of MEMS instrumented microfluidic chips, which were fabricated by combining our leading capabilities in MEMS processing with our low-temperature photolithographic method for fabricating microfluidic channels. We have explored in-situ cantilevers and other similar passive MEMS devices as a new approach to directly sense fluid transport, and have successfully monitored local flow rates and viscosities within microfluidic channels. Actuated MEMS structures have also been incorporated into microfluidic channels, and the electrical requirements for actuation in liquids have been quantified with an elegant theory. Electrostatic actuation in water has been accomplished, and a novel technique for monitoring local electrical conductivities has been invented.
The lead probe neutron detector was originally designed by Spencer and Jacobs in 1965. The detector is based on lead activation due to the following neutron scattering reactions: {sup 207}Pb(n, n'){sup 207m}Pb and {sup 208}Pb(n, 2n){sup 207m}Pb. Delayed gammas from the metastable state of {sup 207m}Pb are counted using a plastic scintillator. The half-life of {sup 207m}Pb is 0.8 seconds. In the work reported here, MCNP was used to optimize the efficiency of the lead probe by suitably modifying the original geometry. A prototype detector was then built and tested. A 'layer cake' design was investigated in which thin (< 5 mm) layers of lead were sandwiched between thicker ({approx} 1 - 2 cm) layers of scintillator. An optimized 'layer cake' design had Figures of Merit (derived from the code) which were a factor of 3 greater than the original lead probe for DD neutrons, and a factor of 4 greater for DT neutrons, while containing 30% less lead. A smaller scale, 'proof of principle' prototype was built by Bechtel/Nevada to verify the code results. Its response to DD neutrons was measured using the DD dense plasma focus at Texas A&M and it conformed to the predicted performance. A voltage and discriminator sweep was performed to determine optimum sensitivity settings. It was determined that a calibration operating point could be obtained using a {sup 133}Ba 'bolt' as is the case with the original lead probe.
This report summarizes the analytical and experimental efforts for the Laboratory Directed Research and Development (LDRD) project entitled 'Obstacle Detection for Autonomous Navigation'. The principal goal of this project was to develop a mathematical framework for obstacle detection. The framework provides a basis for solutions to many complex obstacle detection problems critical to successful autonomous navigation. Another goal of this project was to characterize sensing requirements in terms of physical characteristics of obstacles, vehicles, and terrain. For example, a specific vehicle traveling at a specific velocity over a specific terrain requires a sensor with a certain range of detection, resolution, field-of-view, and sufficient sensitivity to specific obstacle characteristics. In some cases, combinations of sensors were required to distinguish between different hazardous obstacles and benign terrain. In our framework, the problem was posed as a multidimensional, multiple-hypothesis, pattern recognition problem. Features were extracted from selected sensors that allow hazardous obstacles to be distinguished from benign terrain and other types of obstacles. Another unique thrust of this project was to characterize different terrain classes with respect to both positive (e.g., rocks, trees, fences) and negative (e.g., holes, ditches, drop-offs) obstacles. The density of various hazards per square kilometer was statistically quantified for different terrain categories (e.g., high desert, ponderosa forest, and prairie). This quantification reflects the scale, or size, and mobility of different types of vehicles. The tradeoffs between obstacle detection, position location, path planning, and vehicle mobility capabilities were also to be characterized.
This report addresses the development of automated video-screening technology to assist security forces in protecting our homeland against terrorist threats. A threat of specific interest to this project is the covert placement and subsequent remote detonation of bombs (e.g., briefcase bombs) inside crowded public facilities. Different from existing video motion detection systems, the video-screening technology described in this report is capable of detecting changes in the static background of an otherwise, dynamic environment - environments where motion and human activities are persistent. Our goal was to quickly detect changes in the background - even under conditions when the background is visible to the camera less than 5% of the time. Instead of subtracting the background to detect movement or changes in a scene, we subtracted the dynamic scene variations to produce an estimate of the static background. Subsequent comparisons of static background estimates are used to detect changes in the background. Detected changes can be used to alert security forces of the presence and location of potential threats. The results of this research are summarized in two MS Power-point presentations included with this report.
A significant barrier to the deployment of distributed energy resources (DER) onto the power grid is uncertainty on the part of utility engineers regarding impacts of DER on their distribution systems. Because of the many possible combinations of DER and local power system characteristics, these impacts can most effectively be studied by computer simulation. The goal of this LDRD project was to develop and experimentally validate models of transient and steady state source behavior for incorporation into utility distribution analysis tools. Development of these models had not been prioritized either by the distributed-generation industry or by the inverter industry. A functioning model of a selected inverter-based DER was developed in collaboration with both the manufacturer and industrial power systems analysts. The model was written in the PSCAD simulation language, a variant of the ElectroMagnetic Transients Program (EMTP), a code that is widely used and accepted by utilities. A stakeholder team was formed and a methodology was established to address the problem. A list of detailed DER/utility interaction concerns was developed and prioritized. The list indicated that the scope of the problem significantly exceeded resources available for this LDRD project. As this work progresses under separate funding, the model will be refined and experimentally validated. It will then be incorporated in utility distribution analysis tools and used to study a variety of DER issues. The key next step will be design of the validation experiments.
Drainage of water from the region between an advancing probe tip and a flat sample is reconsidered under the assumption that the tip and sample surfaces are both coated by a thin water "interphase" (of width approximately a few nanometers) whose viscosity is much higher than that of the bulk liquid. A formula derived by solving the Navier-Stokes equations allows one to extract an interphase viscosity of ∼59 kPa·s (or ∼6.6 × 10 7 times the viscosity of bulk water at 25°C) from interfacial force microscope measurements with both tip and sample functionalized hydrophilic by OH-terminated tri(ethylene glycol) undecylthiol, self-assambled monolayers.
Coherent cross-track synthetic aperture radar (SAR) stereo is shown to produce high-resolution three-dimensional maps of the earth surface. This mode utilizes image pairs with common synthetic apertures but different squint angles allowing automated stereo correspondence and disparity estimation using complex correlation calculations. This paper presents two Ku-hand, coherent cross-track stereo collects over rolling and rugged terrain. The first collect generates a digital elevation map (DEM) with 1-m posts over rolling terrain using complex SAR imagery with spatial resolution of 0.125 m and a stereo convergence angle of 13.8°. The second collect produces multiple DEMs with 3-m posts over rugged terrain utilizing complex SAR imagery with spatial resolutions better than 0.5 m and stereo convergence angles greater than 40°. The resulting DEMS are compared to ground-truth DEMs and relative height root-mean-square (RMS), linear error 90-percent confidence (LE90), and maximum height error are reported.
We introduce a filter-based evolutionary algorithm (FEA) for constrained optimization. The filter used by an FEA explicitly imposes the concept of dominance on a partially ordered solution set. We show that the algorithm is provably robust for both linear and nonlinear problems and constraints. FEAs use a finite pattern of mutation offsets, and our analysis is closely related to recent convergence results for pattern search methods. We discuss how properties of this pattern impact the ability of an FEA to converge to a constrained local optimum.
The geologic model implicit in the original site characterization report for the Bayou Choctaw Strategic Petroleum Reserve Site near Baton Rouge, Louisiana, has been converted to a numerical, computer-based three-dimensional model. The original site characterization model was successfully converted with minimal modifications and use of new information. The geometries of the salt diapir, selected adjacent sedimentary horizons, and a number of faults have been modeled. Models of a partial set of the several storage caverns that have been solution-mined within the salt mass are also included. Collectively, the converted model appears to be a relatively realistic representation of the geology of the Bayou Choctaw site as known from existing data. A small number of geometric inconsistencies and other problems inherent in 2-D vs. 3-D modeling have been noted. Most of the major inconsistencies involve faults inferred from drill hole data only. Modem computer software allows visualization of the resulting site model and its component submodels with a degree of detail and flexibility that was not possible with conventional, two-dimensional and paper-based geologic maps and cross sections. The enhanced visualizations may be of particular value in conveying geologic concepts involved in the Bayou Choctaw Strategic Petroleum Reserve site to a lay audience. A Microsoft WindowsTM PC-based viewer and user-manipulable model files illustrating selected features of the converted model are included in this report.
These Technical Safety Requirements (TSRs) identify the operational conditions, boundaries, and administrative controls for the safe operation of the Auxiliary Hot Cell Facility (AHCF) at Sandia National Laboratories, in compliance with 10 CFR 830, 'Nuclear Safety Management.' The bases for the TSRs are established in the AHCF Documented Safety Analysis (DSA), which was issued in compliance with 10 CFR 830, Subpart B, 'Safety Basis Requirements.' The AHCF Limiting Conditions of Operation (LCOs) apply only to the ventilation system, the high efficiency particulate air (HEPA) filters, and the inventory. Surveillance Requirements (SRs) apply to the ventilation system, HEPA filters, and associated monitoring equipment; to certain passive design features; and to the inventory. No Safety Limits are necessary, because the AHCF is a Hazard Category 3 nuclear facility.