This report documents work done for a late-start LDRD project, which was carried out during the last quarter of FY07. The objective of this project was to experimentally explore the feasibility of converting vegetable (e.g., soybean) oils to biodiesel by employing slit-channel reactors and solid catalysts. We first designed and fabricated several slit-channel reactors with varying channel depths, and employed them to investigate the improved performance of slit-channel reactors over traditional batch reactors using a NaOH liquid catalyst. We then evaluated the effectiveness of several solid catalysts, including CaO, ZnO, MgO, ZrO{sub 2}, calcium gluconate, and heteropolyacid or HPA (Cs{sub 2.5}H{sub 0.5}PW{sub 12}O{sub 40}), for catalyzing the soybean oil-to-biodiesel transesterification reaction. We found that the slit-channel reactor performance improves as channel depth decreases, as expected; and the conversion efficiency of a slit-channel reactor is significantly higher when its channel is very shallow. We further confirmed CaO as having the highest catalytic activity among the solid catalysts tested, and we demonstrated for the first time calcium gluconate as a promising solid catalyst for converting soybean oil to biodiesel, based on our preliminary batch-mode conversion experiments.
This LDRD began as a three year program to integrate through-wafer vias, micro-mirrors and control electronics with high-voltage capability to yield a 64 by 64 array of individually controllable micro-mirrors on 125 or 250 micron pitch with piston, tip and tilt movement. The effort was a mix of R&D and application. Care was taken to create SUMMiT{trademark} (Sandia's ultraplanar, multilevel MEMS technology) compatible via and mirror processes, and the ultimate goal was to mate this MEMS fabrication product to a complementary metal-oxide semiconductor (CMOS) electronics substrate. Significant progress was made on the via and mirror fabrication and design, the attach process development as well as the electronics high voltage (30 volt) and control designs. After approximately 22 months, the program was ready to proceed with fabrication and integration of the electronics, final mirror array, and through wafer vias to create a high resolution OMEMS array with individual mirror electronic control. At this point, however, mission alignment and budget constraints reduced the last year program funding and redirected the program to help support the through-silicon via work in the Hyper-Temporal Sensors (HTS) Grand Challenge (GC) LDRD. Several months of investigation and discussion with the HTS team resulted in a revised plan for the remaining 10 months of the program. We planned to build a capability in finer-pitched via fabrication on thinned substrates along with metallization schemes and bonding techniques for very large arrays of high density interconnects (up to 2000 x 2000 vias). Through this program, Sandia was able to build capability in several different conductive through wafer via processes using internal and external resources, MEMS mirror design and fabrication, various bonding techniques for arrayed substrates, and arrayed electronics control design with high voltage capability.
Vapor Phase Lubrication (VPL) of silicon surfaces with pentanol has been demonstrated. Two potential show stoppers with respect to application of this approach to real MEMS devices have been investigated. Water vapor was found to reduce the effectiveness of VPL with alcohol for a given alcohol concentration, but the basic reaction mechanism observed in water-free environments is still active, and devices operated much longer in mixed alcohol and water vapor environments than with chemisorbed monolayer lubricants alone. Complex MEMS gear trains were successfully lubricated with alcohol vapors, resulting in a factor of 104 improvement in operating life without failure. Complex devices could be made to fail if operated at much higher frequencies than previously used, and there is some evidence that the observed failure is due to accumulation of reaction products at deeply buried interfaces. However, if hypothetical reaction mechanisms involving heated surfaces are valid, then the failures observed at high frequency may not be relevant to operation at normal frequencies. Therefore, this work demonstrates that VPL is a viable approach for complex MEMS devices in conventional packages. Further study of the VPL reaction mechanisms are recommended so that the vapor composition may be optimized for low friction and for different substrate materials with potential application to conventionally fabricated, metal alloy parts in weapons systems. Reaction kinetics should be studied to define effective lubrication regimes as a function of the partial pressure of the vapor phase constituent, interfacial shear rate, substrate composition, and temperature.
This document provides general guidance for the design and analysis of bolted joint connections. An overview of the current methods used to analyze bolted joint connections is given. Several methods for the design and analysis of bolted joint connections are presented. Guidance is provided for general bolted joint design, computation of preload uncertainty and preload loss, and the calculation of the bolted joint factor of safety. Axial loads, shear loads, thermal loads, and thread tear out are used in factor of safety calculations. Additionally, limited guidance is provided for fatigue considerations. An overview of an associated Mathcad{copyright} Worksheet containing all bolted joint design formulae presented is also provided.
Synthetic Aperture Radar (SAR) performance testing and estimation is facilitated by observing the system response to known target scene elements. Trihedral corner reflectors and other canonical targets play an important role because their Radar Cross Section (RCS) can be calculated analytically. However, reflector orientation and the proximity of the ground and mounting structures can significantly impact the accuracy and precision with which measurements can be made. These issues are examined in this report.
The annual program report provides detailed information about all aspects of the Sandia National Laboratories, California (SNL/CA) Environmental Planning and Ecology Program for a given calendar year. It functions as supporting documentation to the SNL/CA Environmental Management System Program Manual. The program report describes the activities undertaken during the past year, and activities planned in future years to implement the Planning and Ecology Program, one of six programs that supports environmental management at SNL/CA.
This workshop is the fourth one of a series that includes the Neutrino Geophysics Conference at Honolulu, Hawaii, which I attended in 2005. This workshop was organized by the Astro-Particle and Cosmology laboratory in the recently opened Condoret building of the University of Paris. More information, including copies of the presentations, on the workshop is available on the website: www.apc.univ-paris7.fr/AAP2007/. The workshop aims at opening neutrino physics to various fields such that it can be applied in geosciences, nuclear industry (reactor and spent fuel monitoring) and non-proliferation. The workshop was attended by over 60 people from Europe, USA, Asia and Brazil. The meeting was also attended by representatives of the Comprehensive nuclear-Test Ban Treaty (CTBT) and the International Atomic Energy Agency (IAEA). The workshop also included a workshop dinner on board of a river boat sailing the Seine river.
The United States produces only about 1/3 of the more than 20 million barrels of petroleum that it consumes daily. Oil imports into the country are roughly equivalent to the amount consumed in the transportation sector. Hence the nation in general, and the transportation sector in particular, is vulnerable to supply disruptions and price shocks. The situation is anticipated to worsen as the competition for limited global supplies increases and oil-rich nations become increasingly willing to manipulate the markets for this resource as a means to achieve political ends. The goal of this project was the development and improvement of technologies and the knowledge base necessary to produce and qualify a universal fuel from diverse feedstocks readily available in North America and elsewhere (e.g. petroleum, natural gas, coal, biomass) as a prudent and positive step towards mitigating this vulnerability. Three major focus areas, feedstock transformation, fuel formulation, and fuel characterization, were identified and each was addressed. The specific activities summarized herein were identified in consultation with industry to set the stage for collaboration. Two activities were undertaken in the area of feedstock transformation. The first activity focused on understanding the chemistry and operation of autothermal reforming, with an emphasis on understanding, and therefore preventing, soot formation. The second activity was focused on improving the economics of oxygen production, particularly for smaller operations, by integrating membrane separations with pressure swing adsorption. In the fuel formulation area, the chemistry of converting small molecules readily produced from syngas directly to fuels was examined. Consistent with the advice from industry, this activity avoided working on improving known approaches, giving it an exploratory flavor. Finally, the fuel characterization task focused on providing a direct and quantifiable comparison of diesel fuel and JP-8.
Predicting and controlling the evolution of materials microstructure is one of the central challenges of materials science. The simulation of microstructural evolution requires a detailed knowledge of the properties, including energies and mobilities, of interfaces in the material. We present the results of molecular dynamics simulations of these interfacial properties for a large set of boundaries.
This paper reports post-CMOS compatible aluminum nitride dual mode resonator filters that realize 4th order band-pass filters in a single resonator device. Dual mode filters at 106 MHz operating in their fundamental mode are reported with insertion losses as low as 5.5 dB when terminated with 150 Ω. A notching technique is demonstrated for varying the 3 dB bandwidth of these filters from 0.15 to 0.7%, overcoming a significant limitation of previous work. Dual mode filters operating at their 5th and 10th overtones are reported scaling the operating frequencies of this class of device to 0.55 and 1.1 GHz.
This work presents a new type of MEMS resonator based on launching an acoustic wave around a ring. Its maximum frequency is set by electrode spacing and can therefore provide a means for developing resonators with center frequencies in the GHz. In addition since the center frequency is dependent on the average radius it is not subject to lithographic process variations in ring width. We have demonstrated several Ring Waveguide (RWG) Resonators with center frequencies at 484 MHz and 1 GHz. In addition we have demonstrated a 4th order filter based on a RWG design.
Stable and accurate numerical modeling of seismic wave propagation in the vicinity of high-contrast interfaces is achieved with straightforward modifications to the conventional, rectangular-staggered-grid, finite-difference (FD) method. Improvements in material parameter averaging and spatial differencing of wavefield variables yield high-quality synthetic seismic data.
We present a mesh optimization algorithm for adaptively improving the finite element interpolation of a function of interest. The algorithm minimizes an objective function by swapping edges and moving nodes. Numerical experiments are performed on model problems. The results illustrate that the mesh optimization algorithm can reduce the W1,∞ semi-norm of the interpolation error. For these examples, the L2, L∞, and H1 norms decreased also.
This paper presents a new method for handling non-conforming hexahedralto- hexahedral interfaces. One or both of the adjacent hexahedralmeshes are locally modified to create a one-to-onemapping between between themesh nodes and quadrilaterals at the interface allowing a conforming mesh to be created. In the finite element method, non-conforming interfaces are currently handled using constraint conditions such as gapelements, tied contacts, or multi-point constraints. By creating a conforming mesh, the need for constraint conditions is eliminated resulting in a smoother, more precise numerical solution. The method presented in this paper uses hexahedral dual operations, including pillowing, sheet extraction, dicing and column collapse operations, to affect the local mesh modifications. In addition, an extension to pillowing, called sheet inflation, is introduced to handle the insertion of self-intersecting and self-touching sheets. The quality of the resultant conforming hexahedral mesh is high and the increase in number of elements is moderate.
A sub-scale experiment has been conducted to study the trailing vortex shed from a tapered fin installed on a wind tunnel wall to represent missile configurations. Stereoscopic particle image velocimetry measurements have been acquired in the near-field for several locations downstream of the fin tip and at different fin angles of attack. The vortex's tangential velocity is found to decay with downstream distance while its radius increases, but the vortex core circulation remains constant. Circulation and tangential velocity rise greatly for increased fin angle of attack, but the radius is approximately constant or slightly decreasing. The vortex axial velocity is always a deficit, whose magnitude diminishes with downstream distance and smaller angle of attack. No variation with Mach number can be discerned in the normalized velocity data. Vortex roll-up is observed to be largely complete by about four root chord lengths downstream of the fin trailing edge. Prior to this point, the vortex is asymmetric in the tangential velocity but the core radius stays nearly constant. Vortical rotation draws low-speed turbulent fluid from the wind tunnel wall boundary layer into the vortex core, which appears to hasten vortex decay and produce a larger axial velocity deficit than might be expected. Self-similarity of the vortex is established even while it is still rolling up. Attempts to normalize vortex properties by the fin's lift coefficient proved unsuccessful.
Error in Particle Image Velocimetry (PIV) interrogation due to velocity gradients in turbulent flows was studied for both classical and advanced algorithms. Classical algorithms are considered to be digital cross-correlation analysis including discrete window offsets and, for the present work, advanced algorithms are those using image deformation to compensate for velocity gradients. Synthetic PIV simulations revealed substantial negative biases in the turbulent stress for classical algorithms even for velocity gradients within recommended PIV design limits. This bias worsens if the distribution of velocity gradients has a nonzero mean, and error in the mean velocity may be introduced as well. Conversely, advanced algorithms do not exhibit this bias error if the velocity gradients are linear. Nonlinear velocity gradients increase the error in classical algorithms and a significant negative bias in the turbulent stress arises for the advanced algorithm as well. Two experimental data sets showed substantially lower turbulent stresses for the classical algorithm compared with the advanced algorithm, as predicted. No new experimental design rules for advanced algorithms are yet proposed, but any such recommendation would concern second-order velocity derivatives rather than first order.
We demonstrate the power of our technique for establishing and immobilizing well-defined polymer gradients in microchannels by fabricating two miniaturized analytical platforms: microscale immobilized pH gradients (μIPGs) for rapid and high resolution isoelectric focusing (IEF) applications, and polyacrylamide porosity gradients to achieve microscale pore limit electrophoresis (μPLE) in which species are separated based on molecular size by driving them toward the pore size at which migration ceases. Both separation techniques represent the first microscale implementation of their respective methodologies.
A Brain-Emulating Cognition and Control Architecture (BECCA) is presented. It is consistent with the hypothesized functions of pervasive intra-cortical and cortico-subcortical neural circuits. It is able to reproduce many salient aspects of human voluntary movement and motor learning. It also provides plausible mechanisms for many phenomena described in cognitive psychology, including perception and mental modeling. Both "inputs" (afferent channels) and "outputs"' (efferent channels) are treated as neural signals; they are all binary (either on or off) and there is no meaning, information, or tag associated with any of them. Although BECCA initially has no internal models, it learns complex interrelations between outputs and inputs through which it bootstraps a model of the system it is controlling and the outside world. BECCA uses two key algorithms to accomplish this: S-Learning and Context-Based Similarity (CBS).
A sub-scale experiment has been constructed using fins mounted on one wall of a transonic wind tunnel to investigate the influence of fin trailing vortices upon downstream control surfaces. Data are collected using a fin balance instrumenting the downstream fin to measure the aerodynamic forces of the interaction, combined with stereoscopic Particle Image Velocimetry to determine vortex properties. The fin balance data show that the response of the downstream fin essentially is shifted from the baseline single-fin data dependent upon the angle of attack of the upstream fin. Freestream Mach number and the spacing between fins have secondary effects. The velocimetry shows that the vortex strength increases markedly with upstream fin angle of attack, though even an uncanted fin generates a noticeable wake. No variation with Mach number can be discerned in the normalized velocity data. Correlations between the force data and the velocimetry suggest that the interaction is fundamentally a result of an angle of attack superposed upon the downstream fin by the vortex shed from the upstream fin tip. The Mach number influence arises from differing vortex lift on the leading edge of the downstream fin even when the impinging vortex is Mach invariant.
An experiment was conducted comparing the effectiveness of individual versus group electronic brainstorming in addressing real-world "wickedly difficult" challenges. Previous laboratory research has engaged small groups of students in answering questions irrelevant to an industrial setting. The current experiment extended this research to larger, real-world employee groups engaged in addressing organizationrelevant challenges. Within the present experiment, the data demonstrated that individuals performed at least as well as groups in terms of number of ideas produced and significantly (p<.02) outperformed groups in terms of the quality of those ideas (as measured along the dimensions of originality, feasibility, and effectiveness).
Proceedings of the 30th Annual International Conference of the IEEE Engineering in Medicine and Biology Society, EMBS'08 - "Personalized Healthcare through Technology"
The rich history of scalable computing research owes much to a rapid rise in computing platform scale in terms of size and speed. As platforms evolve, so must algorithms and the software expressions of those algorithms. Unbridled growth in scale inevitably leads to complexity. This special issue grapples with two facets of this complexity: scalable execution and scalable development. The former results from efficient programming of novel hardware with increasing numbers of processing units (e.g., cores, processors, threads or processes). The latter results from efficient development of robust, flexible software with increasing numbers of programming units (e.g., procedures, classes, components or developers). The progression in the above two parenthetical lists goes from the lowest levels of abstraction (hardware) to the highest (people). This issue's theme encompasses this entire spectrum. The lead author of each article resides in the Scalable Computing Research and Development Department at Sandia National Laboratories in Livermore, CA. Their co-authors hail from other parts of Sandia, other national laboratories and academia. Their research sponsors include several programs within the Department of Energy's Office of Advanced Scientific Computing Research and its National Nuclear Security Administration, along with Sandia's Laboratory Directed Research and Development program and the Office of Naval Research. The breadth of interests of these authors and their customers reflects in the breadth of applications this issue covers. This article demonstrates how to obtain scalable execution on the increasingly dominant high-performance computing platform: a Linux cluster with multicore chips. The authors describe how deep memory hierarchies necessitate reducing communication overhead by using threads to exploit shared register and cache memory. On a matrix-matrix multiplication problem, they achieve up to 96% parallel efficiency with a three-part strategy: intra-node multithreading, non-blocking inter-node message passing, and a dedicated communications thread to facilitate concurrent communications and computations. On a quantum chemistry problem, they spawn multiple computation threads and communication threads on each node and use one-sided communications between nodes to minimize wait times. They reduce software complexity by evolving a multi-threaded factory pattern in C++ from a working, message-passing program in C.
A coupled Euler-Lagrange solution approach is used to model the response of a buried reinforced concrete structure subjected to a close-in detonation of a high explosive charge. The coupling algorithm is discussed along with a set of benchmark calculations involving detonations in clay and sand.
A total system performance assessment (TSPA) model has been developed to analyze the ability of the natural and engineered barriers of the Yucca Mountain repository to isolate nuclear waste over the period following repository closure. The principal features of the engineered barrier system are emplacement tunnels (or "drifts") containing a two-layer waste package (WP) for waste containment and a titanium drip shield to protect the WP from seeping water and falling rock. The 25-mm-thick outer shell of the WP is composed of Alloy 22, a highly corrosion-resistant nickel-based alloy. There are five nominal degradation modes of the Alloy 22: general corrosion, microbially influenced corrosion, stress corrosion cracking, early failure due to manufacturing defects, and localized corrosion (LC). This paper specifically examines the incorporation of the Alloy 22 LC model into the Yucca Mountain TSPA model, particularly the abstraction and modeling methodology, as well as issues dealing with scaling, spatial variability, uncertainty, and coupling to other submodels that are part of the total system model, such as the submodel for seepage water chemistry.
Future energy systems based on gasification of coal or biomass for co-production of electrical power and fuels may require gas turbine operation on unusual gaseous fuel mixtures. In addition, global climate change concerns may dictate the generation of a CO2 product stream for end-use or sequestration, with potential impacts on the oxidizer used in the gas turbine. In this study the operation at atmospheric pressure of a small, optically accessible swirl-stabilized premixed combustor, burning fuels ranging from pure methane to conventional and H2-rich and H2-lean syngas mixtures is investigated. Both air and CO2-diluted oxygen are used as oxidizers. CO and NOx emissions for these flames have been determined from the lean blowout limit to slightly rich conditions (1.03). In practice, CO2-diluted oxygen systems will likely be operated close to stoichiometric conditions to minimize oxygen consumption while achieving acceptable NOx performance. The presence of hydrogen in the syngas fuel mixtures results in more compact, higher temperature flames, resulting in increased flame stability and higher NOx emissions. Consistent with previous experience, the stoichiometry of lean blowout decreases with increasing H2 content in the syngas. Similarly, the lean stoichiometry at which CO emissions become significant decreases with increasing H2 content. For the mixtures investigated, CO emissions near the stoichiometric point do not become significant until 0.95. At this stoichiometric limit, CO emissions rise more rapidly for combustion in O2-CO2 mixtures than for combustion in air.
A method to measure interfacial mechanical properties at high temperatures and in a controlled atmosphere has been developed to study anodized aluminum surface coatings at temperatures where the interior aluminum alloy is molten. This is the first time that the coating strength has been studied under these conditions. We have investigated the effects of ambient atmosphere, temperature, and surface finish on coating strength for samples of aluminum alloy 7075. Surprisingly, the effective Young's modulus or strength of the coating when tested in air was twice as high as when samples were tested in an inert nitrogen or argon atmosphere. Additionally, the effective Young's modulus of the anodized coating increased with temperature in an air atmosphere but was independent of temperature in an inert atmosphere. The effect of surface finish was also examined. Sandblasting the surface prior to anodization was found to increase the strength of the anodized coating with the greatest enhancement noted for a nitrogen atmosphere. Machining marks were not found to significantly affect the strength.