Publications

Abstract not provided.

Abstract not provided.

Abstract not provided.

Abstract not provided.

Abstract not provided.

The authors present designs of quasi-spherical direction drive z-pinch loads for machines such as ZR at 28 MA load current with a 150 ns implosion time (QSDDI). A double shell system for ZR has produced a 2D simulated yield of 12 MJ, but the drive for this system on ZR has essentially no margin. A double shell system for a 56 MA driver at 150 ns implosion has produced a simulated yield of 130 MJ with considerable margin in attaining the necessary temperature and density-radius product for ignition. They also represent designs for a magnetically insulated current amplifier, (MICA), that modify the attainable ZR load current to 36 MA with a 28 ns rise time. The faster pulse provided by a MICA makes it possible to drive quasi-spherical single shell implosions (QSDD2). They present results from 1D LASNEX and 2D MACH2 simulations of promising low-adiabat cryogenic QSDD2 capsules and 1D LASNEX results of high-adiabat cryogenic QSDD2 capsules.

Abstract not provided.

Abstract not provided.

Abstract not provided.

Abstract not provided.

Abstract not provided.

Abstract not provided.

Abstract not provided.

Abstract not provided.

Abstract not provided.

Abstract not provided.

Abstract not provided.

Abstract not provided.

Abstract not provided.

Abstract not provided.

Abstract not provided.

Abstract not provided.

Abstract not provided.

Abstract not provided.

Abstract not provided.

Abstract not provided.

Abstract not provided.

Abstract not provided.

Abstract not provided.

Abstract not provided.

Abstract not provided.

Abstract not provided.

Abstract not provided.

Abstract not provided.

Abstract not provided.

Abstract not provided.

Abstract not provided.

Abstract not provided.

Abstract not provided.

The development of tools for complex dynamic security systems is not a straight forward engineering task but, rather, a scientific task where discovery of new scientific principles and math is necessary. For years, scientists have observed complex behavior but have had difficulty understanding it. Prominent examples include: insect colony organization, the stock market, molecular interactions, fractals, and emergent behavior. Engineering such systems will be an even greater challenge. This report explores four tools for engineered complex dynamic security systems: Partially Observable Markov Decision Process, Percolation Theory, Graph Theory, and Exergy/Entropy Theory. Additionally, enabling hardware technology for next generation security systems are described: a 100 node wireless sensor network, unmanned ground vehicle and unmanned aerial vehicle.

Abstract not provided.

Abstract not provided.

Abstract not provided.

Abstract not provided.

Abstract not provided.

Abstract not provided.

Abstract not provided.

Abstract not provided.

Abstract not provided.

Abstract not provided.

Abstract not provided.

Abstract not provided.

Abstract not provided.

Abstract not provided.

Abstract not provided.

Abstract not provided.

Abstract not provided.

Abstract not provided.

Abstract not provided.

Abstract not provided.

Abstract not provided.

Abstract not provided.

Abstract not provided.

Abstract not provided.

This report contains the results of a research effort on advanced robot locomotion. The majority of this work focuses on walking robots. Walking robot applications include delivery of special payloads to unique locations that require human locomotion to exo-skeleton human assistance applications. A walking robot could step over obstacles and move through narrow openings that a wheeled or tracked vehicle could not overcome. It could pick up and manipulate objects in ways that a standard robot gripper could not. Most importantly, a walking robot would be able to rapidly perform these tasks through an intuitive user interface that mimics natural human motion. The largest obstacle arises in emulating stability and balance control naturally present in humans but needed for bipedal locomotion in a robot. A tracked robot is bulky and limited, but a wide wheel base assures passive stability. Human bipedal motion is so common that it is taken for granted, but bipedal motion requires active balance and stability control for which the analysis is non-trivial. This report contains an extensive literature study on the state-of-the-art of legged robotics, and it additionally provides the analysis, simulation, and hardware verification of two variants of a proto-type leg design.

Visual simultaneous localization and mapping (VSLAM) is the problem of using video input to reconstruct the 3D world and the path of the camera in an 'on-line' manner. Since the data is processed in real time, one does not have access to all of the data at once. (Contrast this with structure from motion (SFM), which is usually formulated as an 'off-line' process on all the data seen, and is not time dependent.) A VSLAM solution is useful for mobile robot navigation or as an assistant for humans exploring an unknown environment. This report documents the design and implementation of a VSLAM system that consists of a small inertial measurement unit (IMU) and camera. The approach is based on a modified Extended Kalman Filter. This research was performed under a Laboratory Directed Research and Development (LDRD) effort.

Abstract not provided.

Abstract not provided.

Abstract not provided.

Abstract not provided.

Surface chemistry is one of the main factors that contributes to the longevity and compliance of cell patterning. Two to three weeks are required for dissociated, embryonic rat neuronal cultures to mature to the point that they regularly produce spontaneous and evoked responses. Though proper surface chemistry can be achieved through the use of covalent protein attachment, often it is not maintainable for the time periods necessary to study neuronal growth. Here we report a new and effective covalent linking approach using (3-glycidoxypropyl) trimethoxysilane (3-GPS) for creating long term neuronal patterns. Micrometer scale patterns of cell adhesive proteins were formed using microstamping; hippocampal neurons, cultured up to 1 month, followed those patterns. Cells did not grow on unmodified 3-GPS surfaces, producing non-permissive regions for the long-term cell patterning. Patterned neuronal networks were formed on two different types of MEA (polyimide or silicon nitride insulation) and maintained for 3 weeks. Even though the 3-GPS layer increased the impedance of metal electrodes by a factor of 2-3, final impedance levels were low enough that low noise extracellular recordings were achievable. Spontaneous neural activity was recorded as early as 10 days in vitro. Neural recording and stimulation were readily achieved from these networks. Our results showed that 3-GPS could be used on surfaces to immobilize biomolecules for a variety of neural engineering applications. © 2006 Elsevier B.V. All rights reserved.

X-ray powder diffraction data for a rhombohedral AlPt phase formed by self-propagating, high-temperature reactions of AlPt bi-layer films are reported. Multilayer AlPt thin film samples, reacted in air or vacuum, transformed into rhombohedral AlPt with space group R-3(148). Indexing and lattice parameter refinement of AlPt powders (generated from thin-film samples) yielded trigonal/hexagonal unit-cell lattice parameters of a=15.623(6) Å and c=5.305(2) Å, Z=39, and V=1121.5 Å3. © International Centre for Diffraction Data.

We present a new family of stabilized methods for the Stokes problem. The focus of the paper is on the lowest order velocity-pressure pairs. While not LBB compliant, their simplicity and attractive computational properties make these pairs a popular choice in engineering practice. Our stabilization approach is motivated by terms that characterize the LBB "deficiency" of the unstable spaces. The stabilized methods are defined by using these terms to modify the saddle-point Lagrangian associated with the Stokes equations. The new stabilized methods offer a number of attractive computational properties. In contrast to other stabilization procedures, they are parameter free, do not require calculation of higher order derivatives or edge-based data structures, and always lead to symmetric linear systems. Furthermore, the new methods are unconditionally stable, achieve optimal accuracy with respect to solution regularity, and have simple and straightforward implementations. We present numerical results in two and three dimensions that showcase the excellent stability and accuracy of the new methods. © 2006 Society for Industrial and Applied Mathematics.

Periodic processes are ubiquitous in biological systems, yet modeling these processes with high fidelity as periodic orbits of dynamical systems is challenging. Moreover, mathematical models of biological processes frequently contain many poorly-known parameters. This paper describes techniques for computing periodic orbits in systems of hybrid differential-algebraic equations and parameter estimation methods for fitting these orbits to data. These techniques make extensive use of automatic differentiation to evaluate derivatives accurately and efficiently for time integration, parameter sensitivities, root finding and optimization. The resulting algorithms allow periodic orbits to be computed to high accuracy using coarse discretizations. Derivative computations are carried out using a new automatic differentiation package called ADMC++ that provides derivatives and Taylor series coefficients of matrix-valued functions written in the MATLAB programming language. The algorithms are applied to a periodic orbit problem in rigid-body dynamics and a parameter estimation problem in neural oscillations.

Many large-scale computations involve a mesh and first (or sometimes higher) partial derivatives of functions of mesh elements. In principle, automatic differentiation (AD) can provide the requisite partials more efficiently and accurately than conventional finite-difference approximations. AD requires source-code modifications, which may be little more than changes to declarations. Such simple changes can easily give improved results, e.g., when Jacobian-vector products are used iteratively to solve nonlinear equations. When gradients are required (say, for optimization) and the problem involves many variables, "backward" AD in theory is very efficient, but when carried out automatically and straightforwardly, may use a prohibitive amount of memory. In this case, applying AD separately to each element function and manually assembling the gradient pieces - semiautomatic differentiation - can deliver gradients efficiently and accurately. This paper concerns on-going work; it compares several implementations of backward AD, describes a simple operator-overloading implementation specialized for gradient computations, and compares the implementations on some mesh-optimization examples. Ideas from the specialized implementation could be used in fully general source-to-source translators for C and C++.

Nanometric aluminum (123nm, spherical) was mixed with two different sieve-cut sizes of HMX (106-150 μm and 212-300 μm), and a series of gas gun tests were conducted to compare reactive wave development in pure HMX to that of aluminized HMX. In the absence of added metal, 4-mm-thick, low-density (68% of theoretical maximum density) pressings of the 106-150 μm HMX respond to modest shock loading by developing distinctive reactive waves that exhibit both temporal and meso-scale spatial fluctuations. Similar pressings of Al/HMX containing 10% aluminum (by mass) show an initial suppression of the usual wave growth seen in HMX samples. The suppression is then followed by an induction period where it is hypothesized that a phase change in the aluminum may occur. Data from VISAR, line-ORVIS, and 2-color pyrometry are given and discussed, and numerical modeling of inert sucrose is used to aid the explanation of the resulting data.

Impact-flash phenomenology has been known for decades, and is now being considered for missile-defense applications, in particular for remote engagement diagnostics. To technically establish this capability, we have conducted a series of experiments at impact velocities of ∼6, ∼11, and ∼25 km/s. Two- and three-stage light-gas guns were used for the lower two velocities, and magnetically-driven flyers on the Sandia Z machine achieved the higher velocity. Spectrally- and temporally-resolved flash output addressed data reproducibility, material identification, and target configuration analysis. Usable data were obtained at visible and infrared wavelengths. Standard atomic spectral databases were used to identify strong lines from all principal materials used in the study. The data were unique to the individual materials over the wide range of velocities and conditions examined. The time-varying nature of the signals offered the potential for correlation of the measurements with various aspects of the target configuration. Integrating the records over wavelength helped to clarify those time variations. © 2006 American Institute of Physics.

In conducting a probabilistic safety assessment of a nuclear power plant, it is important to identify unsafe actions (UAs) and human failure events (HFEs) that can lead to or exacerbate conditions during a range of incidents initiated by internal or external events. Identification and analysis of UAs and HFEs during a human reliability analysis can be a daunting process that often depends completely on subject matter experts attempting to divine a list of plant conditions and performance shaping factors (PSFs) that may influence incident outcomes. Key to this process of including the most important UAs and resulting HFEs is to speculate upon deviations of specific circumstances from a base case definition of a scenario that may present confusion regarding system diagnosis and appropriate actions (i.e., due to procedures, training, informal rules, etc.). Intuiting the location and impact of such system weaknesses is challenging and careful organization of analyst's approach to this process is critical for defending any argument for completeness of the analysis. Two dimensional distinguishability-confusability matrices were introduced as a tool to test symbol distinguishability for information displays. This paper expands on the tool by presenting multidimensional confusability matrices as a very helpful, pragmatic tool for organizing the process of combining expert judgment regarding system weaknesses, human performance and highly targeted experimentation in a manner that strengthens the quantitative justification for why particular UAs and HFEs were incorporated into a PSA. Furthermore, the particular approach presented here helps to strengthen the justification for specific likelihood determinations (i.e., human error probabilities) that end up being inserted into a probabilistic risk assessment (PRA) or other numerical description of system safety. This paper first introduces the multidimensional confusability matrix (MCM) approach and then applies it to a set of hypothetical loss of coolant accidents (LOCAs) for which a detailed human reliability analysis is desired. The basic structure of the MCM approach involves showing how actual plant states can be mapped to information available to the operators, and then mapping the information available to operator diagnoses and responses. Finally, there is a mapping of actual plant states to operator performance-each mapping is shown to vary along temporally grounded levels of dominant PSFs (e.g., stress, time available, procedures, training, etc.). MCM facilitates comprehensive analysis of the critical signals/information guiding operator diagnoses and actions. Particular manipulations of plant states, available information and PSFs and resulting operator performance may be experimentally gathered using targeted simulator studies, table top exercises with operators, or thought experiments among analysts. It is suggested that targeted simulator studies will provide the best quantitative mappings across the surfaces generated using the MCMs and the best aid to uncovering unanticipated pieces of 'critical' information used by operators. Details of quantifying overall operator performance using the MCM technique are provided. It is important to note that the MCM tool should be considered neutral regarding the issue of so-called 'reductionist' HRA methods (e.g., THERP-type) versus 'holistic' HRA methods (e.g., ATHEANA, MERMOS). If the analyst's support 'reductionist' approaches, then the MCM will represent more of a traditional interval-type, quantitative response surface in their analysis (i.e., more quantitative resolution and generalizability). If the analysis team places more emphasis on 'holistic' approaches, then the MCM will represent more of a nominal cataloging or ordinal ranking of factors influencing their specific analysis. In both types of analyses, the MCM tool helps in organizing, documenting and facilitating quantification of expert judgments and, when resources allow, targeted experimental data to support human reliability analyses. © 2006 by ASME.

A soft-landing actuation waveform was designed to reduce the bounce of a single-pole single-throw (SPST) ohmic radio frequency (RF) microelectromechanical systems (MEMS) switch during actuation. The waveform consisted of an actuation voltage pulse, a coast time, and a hold voltage. The actuation voltage pulse had a short duration relative to the transition time of the switch and imparted the kinetic energy necessary to close the switch. After the actuation pulse was stopped, damping and restoring forces slowed the switch to near-zero velocity as it approached the closed position. This is referred to as the coast time. The hold voltage was applied upon reaching closure to keep the switch from opening. An ideal waveform would close the switch with near zero impact velocity. The switch dynamics resulting from an ideal waveform were modeled using finite element methods and measured using laser Doppler vibrometry. The ideal waveform closed the switch with an impact velocity of less than 3 cm/s without rebound. Variations in the soft-landing waveform closed the switch with impact velocities of 12.5 cm/s with rebound amplitudes ranging from 75 to 150 nm compared to impact velocities of 22.5 cm/s and rebound amplitudes of 150 to 200 nm for a step waveform. The ideal waveform closed the switch faster than a simple step voltage actuation because there was no rebound and it reduced the impact force imparted on the contacting surfaces upon closure. © 2006 IEEE.

We demonstrate a robust approach to VCSEL polarization control using deeply-etched surface gratings oriented at several different rotational angles. A RCWA model is used to optimize the design for high polarization selectivity and fabrication tolerance. © 2006 Optical Society of America.

The 63Sn-37Pb (wt.%, designated Sn-Pb) solder interconnections made to copper (Cu) pads were examined on two printed wiring assemblies (PWAs) that had been in the field for 17 years and subsequently exposed to an accelerated aging test environment. A qualitative assessment of the solder joints indicated that there was excellent solderabiliry of the pins and Cu pads. Void formation was minimal or did not occur at all. Manufacturing defects were limited to minor Cu pad lifting with cracks in the underlying epoxy resin and local areas of Cu barrel separation from the laminate hole wall. Both defects would not have influenced the effects of the accelerated aging environment. A quantitative analysis examined the intermetallic compound (IMC) layer thickness of selected components on the PWAs. The IMC thickness data indicated that the PWAs were exposed to considerably lower, cumulative temperatures inside the product assembly than were present outside as a result of the accelerated aging environment. The quantitative analysis also evaluated the Pb-rich phase particle size in both fillets and the hole region of the PWA solder joints. The Pb-rich phase size confirmed that the temperature environment at the PWA level was significantly less severe than that of the accelerated aging environment. The Pb-rich phase size data indicated that the solder joints were exposed to a limited degree of thermal mechanical fatigue (TMF) that likely originated from the nominal temperature fluctuations coupled with the thermal expansion of the encapsulant as well as large expansion of the circuit board laminate in the z-axis (through-thickness) direction. This study demonstrated the methodology by which, IMC thickness and Pb-rich phase size were used to assess the temperature/time conditions experienced at the Sn-Pb/Cu interconnection level versus the external environment. Copyright © 2006 ASM International®.

An oxidation treatment, often termed "pre-oxidation", is performed on austenitic stainless steel prior to glass/metal joining to produce hermetic seals. The resulting thin oxide acts as a transitional layer and a source of Cr and other elements which diffuse into the glass during the subsequent bonding process. Pre-oxidation is performed in a low pO 2 atmosphere to avoid iron oxide formation and the final oxide is composed of Cr 2O 3, MnCr 2O 4 spinel, and SiO 2. Significant heat-to-heat variations in the oxidation behavior of 304L stainless steel have been observed, which result in inconsistent glass/metal seal behavior. The objectives of this work were to characterize the oxidation kinetics, the oxide morphology and composition, and the stainless steel attributes that lead to robust glass/metal seals. The oxidation kinetics were determined by thermogravimetric (TG) analysis and the oxide layers were characterized using metallography, SEM, focused ion beam (FIB) analysis, and image analysis. The results show that poor sealing behavior is associated with slower oxidation kinetics and a more continuous layer of SiO 2 at the metal/oxide interface. In addition, the effects of 304L heat composition on oxidation behavior will be discussed. Copyright © 2006 ASM International®.

The solderability of an immersion Ag finish was evaluated after the exposure of test specimens to a Battelle Class II environment, which accelerates the storage conditions of light industrial surroundings. The solderability metric was the contact angle, (θC), as determined by the meniscometer/wetting balance technique. Auger surface and depth profile analyses were utilized to identify changes in the coating chemistry. The solderability test results indicate that there was no appreciable loss in solderability when the immersion Ag coated coupons were packaged in vapor phase corrosion (VPC) inhibitor bags and/or inhibitor bags with VPC inhibitor paper and aged for 8 hours, 1 week or 2 weeks in the Battelle Class II environment. An increase in surface carbon concentration after aging did not appear to significantly affect solderability. Copyright © 2006 ASM International®.

The properties of energetic thin films considered for alternative braze[1] techniques are investigated. Vapor-deposited Ni/Ti multilayer foils having a net 1:1 stoichiometry exhibit self-propagating, high temperature combustion reactions. The rate of reaction depends on Ni/Ti multilayer design with steady-state propagation speeds of freestanding foils measured from 0.2 to 1.0m/s. Transmission electron microscopy and x-ray diffraction further show that NiTi films reacted in a self-propagating mode have a fine-grain, polycrystalline microstructure. All films are composed of cubic B2 and monoclinic B19' phases with some having NiTi2 or Ni3Ti precipitates. Copyright © 2006 ASM International®.

Simulations of a low-speed square cylinder wake and a supersonic axisymmetric base wake are performed using the detached eddy simulation model. A reduced-dissipation form of a shock-capturing flux scheme is employed to mitigate the effects of dissipative error in regions of smooth flow. The reduced-dissipation scheme is demonstrated on a two-dimensional square cylinder wake problem, showing a marked improvement in accuracy for a given grid resolution. The results for simulations on three grids of increasing resolution for the three-dimensional square cylinder wake are compared with experimental data and to other computational studies. The comparisons of mean flow and global flow quantities to experimental data are favorable, whereas the results for second order statistics hi the wake are mixed and do not always improve with increasing spatial resolution. Comparisons to large eddy simulation are also generally favorable, suggesting detached eddy simulation provides an adequate subgrid scale model. Predictions of base drag and centerline wake velocity for the supersonic wake are also good, given sufficient grid refinement. These cases add to the validation library for detached eddy simulation and support its use as an engineering analysis tool for accurate prediction of global flow quantities and mean flow properties.

As the economic and environmental impact arguments for increasing the use of nuclear energy for electricity generation and hydrogen production strengthen, it becomes important to better understand human biases, critical thinking skills, and individual specific characteristics that influence decisions made during probabilistic safety assessments (PSAs), decisions regarding nuclear energy among the general public (e.g., trust of risk assessments, acceptance of new plants, etc.), and nuclear energy decisions made by high-level decision makers (e.g., energy policy makers & government regulators). To promote increased understanding and hopefully to improve decision making capacities, this paper provides four key elements. The foundation of these elements builds on decades of research and associated experimental data regarding risk perception and decision making. The first element is a unique taxonomy of twenty-six recognized biases. Examples of biases were generated by reviewing the relevant literature in nuclear safety, cognitive psychology, economics, science education, and neural science (to name a few) and customizing superficial elements of those examples to the nuclear energy domain. The second element is a listing of ten critical thinking skills (with precise definitions) applicable to risk perception and decision making. Third, three brief hypothetical decision making examples are presented and decomposed relative to the unique, decision making bias framework and critical thinking set. The fourth element is a briefly outlined strategy which may enable one to make better decisions in domains that demand careful reflection and strong adherence to the best available data (i.e., avoiding 'unhelpful biases' that conflict with proper interpretation of available data). The elements concisely summarized in this paper (and additional elements) are available in detail in an unclassified, unlimited release Sandia National Laboratories report (SAND2005-5730). The proposed taxonomy of biases contains the headings of normative knowledge, availability, and individual specific biases. Normative knowledge involves a person's skills in combinatorics, probability theory, and statistics. Research has shown that training and experience in these quantitative fields can improve one's ability to accurately determine event likelihoods. Those trained in statistics tend to seek appropriate data sources when assessing the frequency and severity of an event. The availability category of biases includes those which result from the structure of human cognitive machinery. Two examples of biases in the availability category include the anchoring bias and the retrievability bias. The anchoring bias causes a decision maker to bias subsequent values or items toward the first value or item presented to them. The retrievability bias refers to the bias that drives people to believe those values or items which are easier to retrieve from memory are more likely to occur. Individual specific biases include a particular person's values, personality, interests, group identity, and substantive knowledge (i.e., specific domain knowledge related to the decision to be made). Critical thinking skills are also offered as foundational for competent risk perception and decision making as they can mute the impact of undesirable biases, regulate the application of one's knowledge to a decision, and guide information gathering activities. The list of critical thinking skills presented here was originally articulated by the late Arnold B. Arons, a distinguished physicist and esteemed researcher of learning processes. Finally, in addition to borrowing insights from the literature domains mentioned above, the formal decision making approach supported in this paper incorporates methods used in multi-attribute utility theory. © 2006 by ASME.

The objectives of this study are to identify and evaluate alternative protective action recommendations (PARs) that could reduce dose to the public during a radiological emergency and to determine whether improvements or changes to the federal guidance would be beneficial. The emergency response strategies considered in this study are the following: (1) standard radial evacuation; (2) shelter-in-place followed by radial evacuation; (3) shelter-in-place followed by lateral evacuation; (4) preferential sheltering followed by radial evacuation; and (5) preferential sheltering followed by lateral evacuation. Radial evacuation is directly away from the plant; lateral evacuation is azimuthally (around the compass) away from the direction of the wind. Shelter-in-place is a protective action strategy in which individuals remain in their residence, place of work, or other facility at the time that a general warning is given. Preferential sheltering involves moving individuals to nearby, large buildings, e.g., high-school gymnasiums or courthouses, that afford greater protection than personal residences. This study shows that there are benefits to sheltering if followed by lateral evacuation. However, if the lateral evacuation strategy cannot be implemented, then early radial evacuation is often preferable. The most appropriate PAR depends on the evacuation time estimate (ETE) and, therefore, it is desirable to reduce the uncertainty associated with the ETE. Nuclear Regulatory Commission (NRC) guidance to commercial power plants currently allows for sheltering and/or evacuation as an emergency response to a serious nuclear accident. Frequently, however, licensees and states default to evacuation strategies and do not consider sheltering. Here we evaluate several alternative strategies to determine if standard radial evacuation is best or if other options could reduce the overall risk to the public. We consider two source terms based on the NUREG-1150 study. These involve a rapid release of radioactive material into the atmosphere and a more gradual release. Two variations in timing have also been investigated, but are not reported here. The evaluation was performed for a generic site, which uses a uniform population distribution and typical Midwest meteorological data (Moline, IL). Additional parameters that are varied in the study are the ETE (4-, 6-, 8-, and 10-hour ETEs are considered) and the duration of sheltering (2-, 4-, and 8-hr sheltering periods are considered). Additional sensitivity studies were performed to investigate nonuniform evacuation speed caused by traffic congestion, the time needed to reach a preferential shelter, and the effect of adverse weather conditions as opposed to favorable weather conditions. Adverse weather conditions are those for which precipitation occurs before the leading edge of the plume exits the 10-mile emergency planning zone (EPZ). Ultimately, emergency response strategies are ranked by their potential to reduce adverse health effects for residents within the EPZ. © 2006 by ASME.

In order to better understand how the US natural gas network might respond to disruptions, a model was created that represents the network on a regional basis. Natural gas storage for each region is represented as a stock. Transmission between each region is represented as a flow, as is natural gas production, importation, and consumption. Various disruption scenarios were run to test the robustness of the network. The system as modeled proved robust to a variety of disruption scenarios. However, a weakness of the system is that production shortfalls or interruptions cannot be replaced, and demand must therefore be reduced by the amount of the shortfall.

An oxidation treatment, often termed "pre-oxidation", is performed on austenitic stainless steel prior to joining to alkali barium silicate glass to produce hermetic seals. The resulting thin oxide acts as a transitional layer and a source of Cr and other elements which diffuse into the glass during the subsequent bonding process. Pre-oxidation is performed in a low pO2 atmosphere to avoid iron oxide formation and the final oxide is composed of Cr2O3, MnCr2O4 spinel, and SiO2. Significant heat-to-heat variations in the oxidation behavior of 304L stainless steel have been observed, which result in inconsistent glass-to-metal (GTM) seal behavior. The objectives of this work were to characterize the stainless steel pre-oxidized layer and the glass/oxide/304L interface region after glass sealing. The 304L oxidation kinetics were determined by thermogravimetric (TG) analysis and the glass/metal seals characteristics were studied using sessile drop tests, in which wetting angles were measured and glass adhesion was analyzed. The pre-oxidized layers and glass/metal interface regions were characterized using metallography, focused ion beam (FIB) sectioning, scanning and transmission electron microscopy, and electron probe microanalysis (EPMA). The results show that poor glass sealing behavior is associated with a more continuous layer of SiO 2 at the metal/oxide interface.

Radio Frequency Microelectromechanical Systems (RF MEMS) are advantageous for reconfigurable antennas providing the potential for steering, frequency agility, and tunable directivity. Until RF MEMS switches can consistently reach cycles into the billions (if not trillions), limited reliability outweighs the promised benefits, preventing the deployment of RF MEMS into systems. Understanding failure mechanisms is essential to improving reliability. This paper describes preliminary reliability results and tests conducted in a vacuum chamber to investigate and understand the impact of contamination related failure mechanisms. © 2006 IEEE.

Gaussian processes are used as emulators for expensive computer simulations. Recently, Gaussian processes have also been used to model the "error field" or "code discrepancy" between a computer simulation code and experimental data, and the delta term between two levels of computer simulation (multi-fidelity codes). This work presents the use of Gaussian process models to approximate error or delta fields, and examines how one calculates the parameters governing the process. In multi-fidelity modeling, the delta term is used to correct a lower fidelity model to match or approximate a higher fidelity model. The terms governing the Gaussian process (e.g., the parameters of the covariance matrix) are updated using a Bayesian approach. We have found that use of Gaussian process models requires a good understanding of the method itself and an understanding of the problem in enough detail to identify reasonable covariance parameters. The methods are not "black-box" methods that can be used without some statistical understanding. However, Gaussian processes offer the ability to account for uncertainties in prediction. This approach can help reduce the number of high-fidelity function evaluations necessary in multi-fidelity optimization.

Forces generated by a static magnetic field interacting with eddy currents can provide a novel method of vibration damping. This paper discusses an experiment performed to validate modeling [3] for a case where a static magnetic field penetrates a thin sheet of conducting, non-magnetic material. When the thin sheet experiences motion, the penetrating magnetic field generates eddy currents within the sheet. These eddy currents then interact with the static field, creating magnetic forces that act on the sheet, providing damping to the sheet motion. In the presented experiment, the sheet was supported by cantilever springs attached to a frame, then excited with a vibratory shaker. The recorded motions of the sheet and the frame were used to characterize the effect of the eddy current damping.

Multiple references are often used to excite a structure in modal testing programs. This is necessary to excite all the modes and to extract accurate mode shapes when closely spaced roots are present. An algorithm known as SMAC (Synthesize Modes And Correlate), based on principles of modal filtering, has been in development for several years. This extraction technique calculates reciprocal modal vectors based on frequency response function (FRF) measurements. SMAC was developed to accurately extract modes from structures with moderately damped modes and/or high modal density. In the past SMAC has only worked with single reference data. This paper presents an extension of SMAC to work with multiple reference data. If roots are truly perfectly repeated, the mode shapes extracted by any method will be a linear combination of the "true" shapes. However, most closely spaced roots are not perfectly repeated but have some small difference in frequency and/or damping. SMAC exploits these very small differences. The multi-reference capability of SMAC begins with an evaluation of the MMIF (Multivariate Mode Indicator Function) or CMIF (Complex Mode Indicator Function) from the starting frequency list to determine which roots are likely repeated. Several seed roots are scattered in the region of the suspected multiple roots and convergence is obtained. Mode shapes are then created from each of the references individually. The final set of mode shapes are selected based on one of three different selection techniques. Each of these is presented in this paper. SMAC has long included synthesis of FRFs and MIFs from the roots and residues to check extraction quality against the original data, but the capability to include residual effects has been minimal. Its capabilities for including residual vectors to account for out-of-band modes have now been greatly enhanced. The ability to resynthesize FRFs and mode indicator functions from the final mode shapes and residual information has also been developed. Examples are provided utilizing the SMAC package on multi-reference experimental data from two different systems.

A finite element (FE) model of a shell-payload structure is to be used to predict structural dynamic acceleration response to untestable blast environments. To understand the confidence level of these predictions, the model will be validated using test data from a blast tube experiment. The first step in validating the structural response is to validate the loading. A computational fluid dynamics (CFD) code, Saccara, was used to provide the blast tube pressure loading to the FE model. This paper describes the validation of the CFD pressure loading and its uncertainty quantification with respect to experimental pressure data obtained from geometrical mock-up structures instrumented with pressure gages in multiple nominal blast tube tests. A systematic validation approach was used from the uncertainty quantification group at Sandia National Labs. Significant effort was applied to distill the pressure loading to a small number of validation metrics important to obtaining valid final response which is in terms of acceleration shock response spectrum. Uncertainty in the pressure loading amplitude is quantified so that it can be applied to the validation blast tube test on the shell payload structure which has significant acceleration instrumentation but only a few pressure gages.

This paper presents a fictional scenario describing the effects of a category four hurricane on a metropolitan area, accompanied by a challenge: Describe, and eventually realize, a system able to carry out the necessary power system operations without human participation. We outline the capabilities of an automated system for managing electric power. The overarching task of the automated system is islanding: To separate the metro area's power system from the primary power grid and manage its operation during several hurricane-induced contingencies, with the power system operational throughout. The essential technology needed to support this automation is agents. We address the roles agents play in the transition to the islanded state and in power system operation within the island; features of an appropriate agent substrate; the way the agents are organized; and information exchange among agents, the power system, and human operators. ©2006 IEEE.

This work reports on the densification of iron nanoparticles by slow drying followed by pressureless sintering. In contrast, most previous work has used high heating rates to both dry and density the nanoparticle suspension in a single step. Laser heating has been required to achieve high densities by this approach. The slow drying/pressureless sintering approach is shown to be sensitive to reactions between the particles, the stabilizing ligands, the atmosphere, and the substrate. The sintering rate of iron nanoparticles and the final composition of the deposits are significantly impacted by these interactions. However, in both the cases studied, the nanoparticles densify under pressureless sintering. When the iron nanoparticle colloid is dried in a porous steel skeleton, it is shown to increase high-temperature strength and reduce the sintering shrinkage.

Oxygen-fuel fired glass melting furnaces have successfully reduced NO x and particulate emissions and improved the furnace energy efficiency relative to the more conventional air-fuel fired technology. However, full optimisation of the oxygen/fuel approach (particularly with respect to crown refractory corrosion) is unlikely to be achieved until there is improved understanding of the effects of furnace operating conditions on alkali vaporization, batch carryover, and the formation of gaseous air pollutants in operating furnaces. In this investigation, continuous online measurements of alkali concentration (by laser induced breakdown spectroscopy) were coupled with measurements of the flue gas composition in the exhaust of an oxygen/natural gas fired container glass furnace. The burner stoichiometry was purposefully varied while maintaining normal glass production. The data demonstrate that alkali vaporization and SO2 release increase as the oxygen concentration in the exhaust decreases. NOx emissions showed a direct correlation with the flow rate of infiltrated air into the combustion space. The extent of batch carryover was primarily affected by variations in the furnace differential pressure. The furnace temperature did not vary significantly during the measurement campaign, so no clear correlation could be obtained between the available measurements of furnace temperature and alkali vaporization.

Techniques to ensure shock data quality and to recognize bad data are discussed in this paper. For certain shock environments, acceleration response up to ten kHz is desired for structural model validation purposes. The validity and uncertainty associated with the experimental data need to be known in order to use it effectively in model validation. In some cases the frequency content of impulsive or pyrotechnic loading or metal to metal contact of joints in the structure may excite accelerometer resonances at hundreds of kHz. The piezoresistive accelerometers often used to measure such events can provide unreliable data depending on the level and frequency content of the shock. The filtered acceleration time history may not reveal that the data are unreliable. Some data validity considerations include accelerometer mounting systems, sampling rates, band-edge settings, peak acceleration specifications, signal conditioning bandwidth, accelerometer mounted resonance and signal processing checks. One approach for uncertainty quantification of the sensors, signal conditioning and data acquisition system is also explained.

A flexible, robust method for linking grids of locally refined ground-water flow models constructed with different numerical methods is needed to address a variety of hydrologic problems. This work outlines and tests a new ghost-node model-linking method for a refined "child" model that is contained within a larger and coarser "parent" model that is based on the iterative method of Steffen W. Mehl and Mary C. Hill (2002, Advances in Water Res., 25, p. 497-511; 2004, Advances in Water Res., 27, p. 899-912). The method is applicable to steady-state solutions for ground-water flow. Tests are presented for a homogeneous two-dimensional system that has matching grids (parent cells border an integer number of child cells) or nonmatching grids. The coupled grids are simulated by using the finite-difference and finite-element models MODFLOW and FEHM, respectively. The simulations require no alteration of the MODFLOW or FEHM models and are executed using a batch file on Windows operating systems. Results indicate that when the grids are matched spatially so that nodes and child-cell boundaries are aligned, the new coupling technique has error nearly equal to that when coupling two MODFLOW models. When the grids are nonmatching, model accuracy is slightly increased compared to that for matching-grid cases. Overall, results indicate that the ghost-node technique is a viable means to couple distinct models because the overall head and flow errors relative to the analytical solution are less than if only the regional coarse-grid model was used to simulate flow in the child model's domain.

A discussion on an active gas imager that can potentially improve system performance and reliability in Smart Leak Detection and Repair covers conventional single-wavelength imaging; differential imaging; methane detection; modification for detecting fugitive emissions relevant to refineries and chemical plants; and system description. This is an abstract of a paper presented at the AWMA's 99th Annual Conference and Exhibition (New Orleans, LA 6/20-23/2006).

The RADTRAN Loss of Shielding (LOS) Model was benchmarked using MicroShield 6.20®. This analysis considers an intact spent fuel truck cask as well as a set of damaged truck casks. Ratios of dose rates are calculated for casks with a loss of lead shielding to those of intact casks, and are then compared to ratios generated by the LOS model. LOS Model results were considered verified if two main constraints were satisfied. First, the dose rate profiles for both the LOS and MicroShield 6.20® calculations must have the same general shape and behavior. Additionally, the largest factor difference between any two points of the dose rate profiles may not exceed an order of magnitude. Reasonable agreement is shown for large-fraction LOS scenarios; however the differences in results are not satisfactory for cases with small fractions of slump.

A wide variety of MicroElectroMechanical Systems (MEMS) are fabricated using existing novel technologies. State-of-the art integrated circuit (IC) fabrication methods are used for the fabrication of these MEMS. The fabrication of these structures requires many process steps that include deposition, patterning, etching, and CMP. The use of CMP enables the fabrication of complex, multi-level MEMS. Similar to IC fabrication, there are concerns about non-uniformity, erosion and dishing after CMP, but because of the thickness of the materials, CMP processing issues are amplified. Unlike ICs, there is no transistor basic building block so processing must be technology specific and process development is driven by the device/system performance requirements, which are very specific to the application.

Abstract not provided.

We apply ab initio molecular dynamics (AIMD) to study the hydration structures and electronic properties of the formohydroxamate anion in liquid water. We consider the cis- nitrogen-deprotonated, cis- oxygen-deprotonated, and trans- oxygen-deprotonated formohydroxamate tautomers. They form an average of 6.3, 6.9, and 6.0 hydrogen bonds with water molecules, respectively. The predicted pair correlation functions and time dependence of the hydration numbers suggest that water is highly structured around the nominally negatively charged oxime oxygen in O-deprotonated tautomers but significantly less so around the nitrogen atom in the N-deprotonated species. Wannier function analysis suggests that, in the O-deprotonated anions, the negative charge is concentrated on the oxime oxygen, while in the N-deprotonated case, it is partially delocalized between the nitrogen and the adjoining oxime oxygen atom. © 2006 Elsevier B.V. All rights reserved.

A differential system that models the circadian rhythm in Drosophila is analyzed with the computational singular perturbation (CSP) algorithm. Reduced nonstiff models of prespecified accuracy are constructed, the form and size of which are time-dependent. When compared with conventional asymptotic analysis, CSP exhibits superior performance in constructing reduced models, since it can algorithmically identify and apply all the required order of magnitude estimates and algebraic manipulations. A similar performance is demonstrated by CSP in generating data that allow for the acquisition of physical understanding. It is shown that the processes driving the circadian cycle are (i) mRNA translation into monomer protein, and monomer protein destruction by phosphorylation and degradation (along the largest portion of the cycle); and (ii) mRNA synthesis (along a short portion of the cycle). These are slow processes. Their action in driving the cycle is allowed by the equilibration of the fastest processes; (1) the monomer dimerization with the dimer dissociation (along the largest portion of the cycle); and (2) the net production of monomer+dimmer proteins with that of mRNA (along the short portion of the cycle). Additional results (regarding the time scales of the established equilibria, their origin, the rate limiting steps, the couplings among the variables, etc.) highlight the utility of CSP for automated identification of the important underlying dynamical features, otherwise accessible only for simple systems whose various suitable simplifications can easily be recognized. © 2006 Society for Industrial and Applied Mathematics.

When a micro cantilever beam is excited by base shaking, electrostatic force makes the tip displacement response nonlinear with respect to the base acceleration input. This paper derives a single-degree-of-freedom model for the deflection in a micro cantilever due to electrostatic voltage for this excitation. The tip deflection due to electrostatic force is derived first as part of the total tip deflection, and then in terms of an equivalent base excitation. The relationship between electrostatic deflection and equivalent base excitation is determined numerically, but can be represented accurately by a simple curve-fit function.

Electroslag Remelting (ESR) is a complex process used to produce high quality specialty alloy materials. The quality can be directly correlated to variances in melt rate and immersion depth. Conventional ESR furnaces control these quantities using two independent control loops using proportional changes in current for melt rate and driving the electrode up and down to match a voltage set point for immersion depth. However it is well known that the control loops are highly coupled, i.e. changing the current to account for melt rate deviations changes the voltage depth relationship and vice verse. In addition the noise in measurements of the ESR process can be considerable, forcing conventional controllers to use highly damped responses. A new model-based controller has been developed to embody the coupling and improve responsiveness by using estimates from a reduced-order linear ESR model and the typical process measurements to control melt rate and immersion depth simultaneously. Kalman filtering is used to optimally combine the model estimates of eight process states and the measurements of voltage, current, position and mass to estimate the instantaneous melt rate and immersion depth. Several ESR melts under steady state and transient conditions were conducted to evaluate the performance of the new controller. This paper will discuss the design of the new ESR model and controller and will present experimental results demonstrating its much improved control and responsiveness. While this controller was developed for the ESR process, the effectiveness of model-based control in managing such a complex process with relatively simple equations suggests the approach could be employed for many other processes as well.

The counter-rotating-ring receiver/reactor/recuperator (CR5) solar thermochemical heat engine is a new concept for production of hydrogen that allows for thermal recuperation between solids in an efficient counter-current arrangement. At the heart of the CR5 system are annular rings of a reactive solid ferrite that are thermally and chemically cycled to produce oxygen and hydrogen from water in separate and isolated steps. This design is very demanding from a materials point of view. The ferrite rings must maintain structural integrity and high reactivity after months of thermal cycling and exposure to temperatures in excess of 1100°C. In addition, the design of the rings must have high geometric surface area for gas-solid contact and for adsorption of incident solar radiation. After performing a series of initial screenings, we chose Co0.67Fe2.33O4 as our baseline working material for a planned demonstration of CR5 and have begun additional characterization and development of this material. Our results to date with powders are consistent with the expectation that small particle sizes and the application of a support to inhibit ferrite sintering and enhance the chemistry are critical considerations for a practical operating device. Concurrent with the powder studies, we are using Robocasting, a Sandia-developed technique for free form processing of ceramics, to manufacture monolithic structures with complex three-dimensional geometries for chemical, physical, and mechanical evaluation. We have demonstrated that ferrite/zirconia mixtures can be fabricated into small three-dimensional monolithic lattice structures that give reproducible hydrogen yields over multiple cycles. Copyright © 2006 by ASME.

Sandia has conducted a number of tests in search of conformal coating products that function acceptably at 225°C or higher. This paper documents the work associated with the initial testing of organic and organic-inorganic materials for this purpose and provides information on materials found which failed initial testing and those materials which show promise. The report also provides insight into our testing process, which is designed to represent the wellbore environment. Copyright © 2006 International Microelectronics And Packaging Society.

This paper 1 develops a novel control system design methodology that uniquely combines: concepts from thermodynamic exergy and entropy; Hamiltonian systems; Lyapunov's direct method and Lyapunov optimal analysis; electric AC power concepts; and power flow analysis. Relationships are derived between exergy/entropy and Lyapunov optimal functions for Hamiltonian systems. The methodology is demonstrated with two fundamental numerical simulation examples: 1) a Duffing oscillator/Coulomb friction nonlinear model that employs PID regulator control and 2) a van der Pol nonlinear oscillator system. The control system performances and/or appropriately identified terms are partitioned and evaluated based on exergy generation and exergy dissipation terms. This novel nonlinear control methodology results in both necessary and sufficient conditions for stability of nonlinear systems.

This paper 1 develops a novel control system design methodology that uniquely combines: concepts from thermodynamic exergy and entropy; Hamiltonian systems; Lyapunov's direct method and Lyapunov optimal analysis; electric AC power concepts; and power flow analysis. Relationships are derived between exergy/entropy and Lyapunov optimal functions for Hamiltonian systems. The methodology is demonstrated with two fundamental numerical simulation examples: 1) a Duffing oscillator/Coulomb friction nonlinear model that employs PID regulator control and 2) a van der Pol nonlinear oscillator system. The control system performances and/or appropriately identified terms are partitioned and evaluated based on exergy generation and exergy dissipation terms. This novel nonlinear control methodology results in both necessary and sufficient conditions for stability of nonlinear systems.

A series of pressurized sulfuric acid decomposition tests are being performed to (1) obtain data on the fraction of sulfuric acid catalytically converted to sulfur dioxide, oxygen, and water as a function of temperature and pressure, (2) demonstrate real-time measurements of acid conversion for use as process control in the Sulfur-Iodine (SI) thermochemical cycle, and (3) obtain multiple measurements of conversion as a function of temperature within a single experiment. Acid conversion data are presented at pressures of 6 and 11 bars in the temperature range of 750 - 875 °C. The design for an acid decomposer section with heat and mass recovery of undecomposed acid using a direct contact heat exchanger are presented.

An investigation was conducted into factors that effect impedance for a 2.5 MV gas switch. The switch studied was Rimfire, the workhorse gas switch topology for many of Sandia's large accelerators. The geometry of the switch investigated consists of multiple self-break gaps in series with a laser triggered main gap. The switch is situated within a coaxial-like ground return structure. In this geometry there are three avenues that are theoretically possible for reducing switch impedance. They are 1) increasing the number of parallel current sharing channels (multichanneling), 2) decreasing the ratio of radii of the outer to inner conductors, and/or 3) decreasing the length. It was experimentally determined what effects the first two factors have on switch impedance and the results are presented in this work. It was discovered that multichanneling and radii ratio have substantially lesser effects on impedance, when compared to the theoretical effects of a reduction in switch length. This leaves reduction in length as the only remaining significant viable option for reduction of impedance in megavolt multigap switches, which has substantial consequences for the future design of multigap switches. ©2006 IEEE.

Monitoring programs for nuclear-waste repositories are now conceived as an exercise in performance confirmation: the purpose of the monitoring program is to provide objective evidence that the repository system is functioning as expected. However, monitoring is still largely seen as being entirely focused on the near-repository environment, with the aim of verifying predictions made about such things as temperature or rock mass behavior that are relevant to the designed functioning of the repository. A more comprehensive approach comes from recognizing that the repository is embedded in a larger natural system that may be affected by factors in addition to the repository. At some current or prospective repository sites, various human activities that are amenable to monitoring might potentially (or actually) affect the natural system. Observing these anthropogenically induced changes in the natural system and being able to simulate them accurately using the models already constructed for repository performance assessment provide an additional opportunity for performance confirmation. Water-level changes induced by oil and gas exploration and/or potash mining activities near the Waste Isolation Pilot Plant site provided an opportunity to confirm important features of the groundwater model used in performance assessment calculations. Repository programs should evaluate the potential for ongoing or future human activities to affect the systems in which their repositories are situated and provide an opportunity for performance confirmation.

Abstract not provided.

We report on colloidal synthesis of InP and InN nanocrystals (NCs) from organometallic precursors in a noncoordinating solvent using myristic acid as a ligand. The results of NC structural and optical characterization are presented. © 2006 Optical Society of America.

Acoustic wave propagation in a three-dimensional atmosphere that is spatially heterogeneous, time-varying, and/or moving is accurately simulated with a numerical algorithm recently developed under the DOD Common High Performance Computing Software Support Initiative (CHSSI). Sound waves within such a dynamic environment are mathematically described by a set of four, coupled, first-order partial differential equations governing small-amplitude fluctuations in pressure and particle velocity. The system is rigorously derived from fundamental principles of continuum mechanics, ideal-fluid constitutive relations, and reasonable assumptions that the ambient atmospheric motion is adiabatic and divergence-free. An explicit, finite-difference time-domain (FDTD) numerical scheme is used to solve the system for both pressure and particle velocity wavefields. Dependent variables are stored on staggered spatial and temporal grids, and centered FDTD operators possess 2nd-order and 4th-order space/time accuracy. We first present results of a test that shows the accuracy of our algorithm by comparison with analytic formulations. We then present a contrast and comparison of the sound character at a series of distances from a point source activated with a causal source. We are able to investigate the effects of turbulence, complex meteorology (including wind effects), a topographically variable ground surface, and a partially reflective ground surface.

A series of pressurized sulfuric acid decomposition tests are being performed to (1) obtain data on the fraction of sulfuric acid catalytically converted to sulfur dioxide, oxygen, and water as a function of temperature and pressure, (2) demonstrate real-time measurements of acid conversion for use as process control in the Sulfur-Iodine (SI) thermochemical cycle, and (3) obtain multiple measurements of conversion as a function of temperature within a single experiment. Acid conversion data are presented at pressures of 6 and 11 bars in the temperature range of 750 - 875 °C. The design for an acid decomposer section with heat and mass recovery of undecomposed acid using a direct contact heat exchanger are presented.

Laser Engineered Net-shaping (LENS®) can directly manufacture near net shape metallic components from CAD files. The thermal history associated with LENS® process, which involves numerous reheating cycles, is critical to the microstructural evolution and mechanical properties of the LENS® fabricated parts. In this paper, the surface morphology of as-atomized PH13-8Mo steel powder is characterized; Variation of the height of deposited materials with process parameters is measured; Microhardness and tensile tests are carried out to evaluate the mechanical performance of LENS® deposited PH13-8Mo components; Microstructural analysis is conducted using OM, SEM, TEM to understand the microstructural evolution of the LENS® deposited PH13-8Mo samples; The thermal history and its effects on microstructural evolution and resultant mechanical properties is studied in order to understand the relationship between processing parameter, microstructure and mechanical properties of the LENS® fabricated PH13-8Mo components.

The heat output of the radioactive waste proposed to be emplaced at Yucca Mountain will strongly affect the thermal-hydrological (TH) conditions in and near the geologic repository for thousands of years. Recent computational fluid dynamics (CFD) analysis has demonstrated that the emplacement tunnels (drifts) will act as important conduits for gas flows driven by natural convection. As a result, vapor generated from boiling/evaporation of formation water near elevated-temperature sections of the drifts may effectively be transported to cooler end sections (where no waste is emplaced), would condense there, and subsequently drain into underlying rock units. To study these processes, we have developed a new simulation method that couples existing tools for simulating TH conditions in the fractured formation with modules that approximate natural convection in heated emplacement drifts. The new method is applied to evaluate the future TH conditions at Yucca Mountain in a three-dimensional model domain comprising a representative emplacement drift and the surrounding fractured rock.

A tunable electrically small PIFA-as-a-package antenna for miniature wireless device applications has been developed using conventional printed circuit board processing techniques and commercial-off-the-shelf surface mount switches. The design is scalable to any frequency and form factor, while enabling adaptive tuning of the characteristically narrow band resonance of electrically small antennas. Our UHF prototype measures less than 2" (.08λ) on its longest side and provides approximately - 9dBi of gain from 419-472 MHz. Simulated and measured results will be discussed in the presentation.

Asynchronous integrated circuit technology provides low-power and low-noise operation for portable electronic security applications. Rather than using a global clock, asynchronous circuits employ a system of distributed handshake signals that control on-chip dataflow; reducing power consumption to only those parts of a chip actively involved in computation. Sandia has developed an automated asynchronous design flow that enables the rapid development of these asynchronous ASICs. This paper describes the design of asynchronous DES encryption circuits using this flow, and evaluates their performance against standard synchronous implementations. © 2006 IEEE.

The effects of diameter on detonation velocity of packed granular beds of HNS (2,2',4,4',6,6'-hexanitrostilbene) and CL-20 (2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaazaisowurtzitane, HNIW) will be discussed. Due to the novel nature of the diagnostic technique utilized here, a thorough discussion of the experimental method is provided. The dimension at which finite diameter effects occur was characterized by conducting simultaneous streak camera and framing camera measurements on miniature rate sticks similar in concept to traditional rate sticks. A significant difference between historical rate sticks and those discussed here comes in the form of how they were produced. A femtosecond laser was used to generate precision miniature rate sticks down to diameters of 187 μm. Finally, we will discuss the somewhat unexpected result of nano particulate generation of energetic materials due to the laser machining process.

Encapsulation of high voltage transformers can be a difficult undertaking. Stresses arise due to the coefficient of thermal expansion (CTE) mismatch of the components. Due to the viscoelastic nature of the encapsulation, these stresses can change over time. Excessive tensile stress in the ceramic cores results in cracks which can affect the performance of the transformer. The transformer that is the subject of this paper performed well after manufacturing and an initial thermal cycle; four years later however, the same transformer failed during the heat-up portion of a similar thermal cycle. X-rays revealed a large crack in the ceramic core. This paper summarizes the elastic and nonlinear viscoelastic finite element modeling that was done in support of the failure investigation and redesign of the transformer. In both the elastic and viscoelastic finite element models, the maximum principal tensile stresses at the low temperature condition of the thermal cycle exceeded the estimated ultimate tensile strength of the core material. At room temperature, the models predicted that the maximum principal tensile stresses were sufficiently high to produce subcritical crack growth in the core material. The viscoelastic model indicated that the core could experience a significant increase in stress due to physical aging of the encapsulation. Modeling stresses compared well to the cracks found in the failed transformer. The final design utilized a silicone coating applied to the interior surfaces of the cores. The coating acts as a stress relief layer that decouples the high CTE encapsulation from the ceramic core. The addition of the silicone coating resulted in a significant stress reduction. X-rays of transformers made with the silicone coating reveal no cracks in the cores.

This paper presents results on the electro-thermo-mechanical behavior of piezoelectric materials for use in actuator applications with an emphasis on durability performance. The objective of this study was to compare the performance of different commercially available actuator systems and to determine the properties necessary for the design of such actuator systems. Basic piezoelectric properties of five stack actuators were determined as a function of mechanical preload and temperature. Changes in these properties during ferroelectric fatigue up to 107 cycles were determined from strain-field relations after a specified number of fatigue cycles. Experimental results indicate a strong dependence of piezoelectric properties and power requirements on mechanical loading conditions. Results indicate that the optimum operating conditions (i.e., mechanical preload) that will improve actuation capabilities of piezoelectric stack actuators can be determined. That is, strain output was found to increase by 60% for some actuators upon the application of certain compressive prestress. Results of fatigue tests indicate negligible degradation in strain output for some stack actuators even when operated under mechanical preload that causes large displacements through domain wall motion. Similar trends in strain output and current degradation curves (as a function of fatigue cycles) suggest that material degradation can be indirectly inferred from simply measuring the current being dissipated by the material and the fatigue predicted by measuring the strain output (quantity related to domain motion). Finally, temperature rise of lead zirconate titanate stacks due to self-heating should be taken into account when designing actuator systems, since temperature changes were found to significantly influence both strain output and power required to drive piezoelectric stack actuators. Physical mechanisms of ferroelectric fatigue are explored. © 2006 American Institute of Physics.

A new approach to explosive sample preparation is described in which microelectronics-related processing techniques are utilized. Fused silica and alumina substrates were prepared utilizing laser machining. Films of PETN were deposited into channels within the substrates by physical vapor deposition. Four distinct explosive behaviors were observed with high-speed framing photography by driving the films with a donor explosive. Initiation at hot spots was directly observed, followed by either energy dissipation leading to failure, or growth to a detonation. Unsteady behavior in velocity and structure was observed as reactive waves failed due to decreasing channel width. Mesoscale simulations were performed to assist in experiment development and understanding. We have demonstrated the ability to pattern these films of explosives and preliminary mesoscale simulations of arrays of voids showed effects dependent on void size and that detonation would not develop with voids below a certain size. Future work involves experimentation on deposited films with regular patterned porosity to elucidate mesoscale explosive behavior.

The RandomAccess benchmark as defined by the High Performance Computing Challenge (HPCC) tests the speed at which a machine can update the elements of a table spread across global system memory, as measured in billions (giga) of updates per second (GUPS). The parallel implementation provided by HPCC typically performs poorly on distributed-memory machines, due to updates requiring numerous small point-to-point messages between processors. We present an alternative algorithm which treats the collection of P processors as a hypercube, aggregating data so that larger messages are sent, and routing individual datums through dimensions of the hypercube to their destination processor. The algorithm's computation (the GUP count) scales linearly with P while its communication overhead scales as log2(P), thus enabling better performance on large numbers of processors. The new algorithm achieves a GUPS rate of 19.98 on 8192 processors of Sandia's Red Storm machine, compared to 1.02 for the HPCC-provided algorithm on 10350 processors. We also illustrate how GUPS performance varies with the benchmark's specification of its "look-ahead" parameter. As expected, parallel performance degrades for small look-ahead values, and improves dramatically for large values. © 2006 IEEE.

Future energy systems based on gasification of coal or biomass for co-production of electrical power and gaseous or liquid fuels may require gas turbine operation on unusual fuel mixtures. In addition, global climate change concerns may dictate the production 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 the oxidizers. CO and NOx emissions for these flames have been determined over the full range of stoichiometrics from the lean blow-off limit to slightly rich conditions (φ ∼ 1.03). 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. The lean blowoff limit and the lean stoichiometry at which CO emissions become significant both decrease with increasing H2 content in the syngas. For the investigated mixtures, CO emissions near the stoichiometric point do not become significant until (φ > 0.95. At this stoichiometric limit, where dilute-oxygen power systems would preferably operate, CO emissions rise more rapidly for combustion in O2-CO2 mixtures than for combustion in air.

The flexibility gained in moving from an analog video system to a digital video system is immeasurable, and the onslaught of new IP-addressable cameras and recording solutions has given security system designers an endless set of options for migrating to a digital video system. Video can be brought up and viewed by any authorized user on the security network, and adding new devices is as easy as plugging them into the security network. However, the change to an IP-based framework also leads to a completely different set of considerations-What kind of bandwidth does the network infrastructure need in order to handle all the video streaming across it? How do you integrate an IP video system into the rest of a Physical Security System (including Entry Control, Command, Control, and Communication)? This paper will address these considerations, among others, to help guide security system designers in determining the type of video system best suited for their applications. © 2006 IEEE.

A mesoscale dimensional artifact based on silicon bulk micromachining fabrication has been developed with the intention of evaluating the artifact both on a high precision Coordinate Measuring Machine (CMM), and on a video-probe based measuring system. A high accuracy touch-probe based CMM can achieve accuracies that are as good as the 2-D repeatability of video-probe systems. While video-probe based systems are commonly used to inspect mesoscale mechanical components, a video-probe system's certified accuracy is generally much worse than its repeatability. By using a hybrid artifact where the same features can be extracted by both a touch-probe and a video-probe, the accuracy of video-probe systems can be improved. In order to use the micromachined device as a calibration artifact, it is important to understand the uncertainty present in the touch-probe measurements. An uncertainty analysis is presented to show the potential accuracy of the measurement of these artifacts on a high precision CMM.

To combat the security threats of the 21st century it has become increasingly necessary to protect ever-remote terrain with wireless sensor surveillance. These systems must be self-sustaining to ensure they are constantly operational. Sandia developed a software simulation tool to validate a variety of renewable energy sources for commercial needs. While this software is heavily used in industry it has yet to be fully applied to wireless sensor networks. Based on simulated solar energy yields two different solar energy systems were designed, built, and deployed to the field. In the time since the solar energy power supplies were deployed zero hours have been spent on maintenance and it was not necessary to replace a single battery. © 2006 IEEE.

There is a need to provide response force personnel with advanced warning of intruder activity in rough terrain outside the traditional facility perimeter. Often the land surrounding a high consequence facility is remote and difficult to sensor with conventional long-range detection systems. In order to combat this difficult problem, Sandia has investigated, developed, and fielded a wireless sensor network that demonstrated the value of providing advanced information of adversary activities. The project used wireless technologies to detect and assess intruders in remote 'un-engineered' terrain around a fixed facility. In the time since the wireless intrusion detection system was fielded, minimal time has been spent on maintenance and no batteries required replacement Sandia's wireless sensor network provides advanced warning of intruder activities and its installation will improve the security posture of a facility. © 2006 IEEE.

Numerical methods are employed to examine the transport of charged species in pressure-driven and electroosmotic flow along nanoscale channels having an electric double-layer thickness comparable to the channel size. In such channels, the electric field inherent to the double layer produces transverse species distributions that depend on species charge. Flow along the channel thus yields mean axial species speeds that also depend on the species charge, enabling species separation and identification. Here we characterize field-flow separations of this type via the retention and plate height. For pressure-driven flows, we demonstrate that mean species speeds along the channel are uniquely associated with a single species charge, allowing species separation based on charge alone. In contrast, electroosmotic flows generally yield identical speeds for several values of the charge, and these speeds generally depend on both the species charge and electrophoretic mobility. Coefficients of dispersion for charged species in both planar and cylindrical geometries are presented as part of this analysis. © 2006 American Chemical Society.

This paper describes a high-rel transformer design and the design iterations required to meet the severe environments of military grade transformers. It describes a method of reducing the mechanical stress caused when a ferrite pot core is encapsulated in a rigid epoxy. Stresses are due to differences in coefficient of thermal expansion between the two materials. The mechanical design optimization of a small flyback transformer designed to charge an energy storage capacitor up to 6 kV from a low voltage source is described. The basic design uses a 2616 manganese zinc ferrite pot core. The goal was to eliminate the core cracking problem. The purpose for writing and presenting this paper is to document a proven process that evolved out of necessity, and to present to the industry a method which reduces stresses on the core, eliminates cracking of the core and provides the insulation necessary for small high voltage transformers.

Organic polymer materials are used frequently in structures and transportation systems. Polymer materials may provide fuel for a fire or be damaged catastrophically due to an incident heat flux. Modeling the response of such structures and systems in fire environments has important applications in safety and vulnerability analyses. The decomposition chemistry of the organic polymer materials is an important factor in many analyses. To provide input to numerical models for hazard and vulnerability analyses, the thermal decomposition chemistry of organic polymers is being experimentally investigated using TGA-FTIR, GC-FTIR, infrared microprobe (IRMP), and DSC Both TGA-FTIR and DSC experiments are done with unconfined and partially confined samples. Unconfined samples are used to examine initial decomposition reactions. Partially confined samples are used to examine reversible and secondary reactions. This paper discusses phenomena pertinent to using the aforementioned techniques to develop rate expressions for polymer decomposition reactions, and a specific example illustrating development of rate expressions for decomposition of PMMA is given.

Decomposition of PGN (Poly Glycidyl Nitrate) has been investigated using TJump/ FTIR (Fourier Transform Infrared Spectroscopy) and STMBMS (Simultaneous Thermogravimetric Modulated Beam Mass Spectrometry) in an effort to understand the effects of hydroxyl end-modification and isocyanate curing of PGN. T-Jump/FTIR allows real-time determination and quantification of decomposition gas products as samples are heated very fast (20°C/s) to simulate deflagration conditions. Our results identify decomposition gas products including: CH2O, H2O, CO2, CO, N2O, NO, NO2, HCN and HONO. PGN deflagration kinetic rates relative to CO2 formation and preliminary results on the effects of hydroxyl end-capping are presented. Slow heating, STMBS experiments aid in discerning possible mechanistic pathways by temporally separating decomposition gas products as they evolve. These results show that thermal decomposition of PGN is controlled by a three step reaction process: (I) decomposition of the CH2-ONO2 functional moiety, (II) reactions of initial low-molecular-weight species with each other, and (III) reactions of lowmolecular-weight species with the polymer backbone. While this work focuses only on ncured PGN prepolymer, future results will include the effects of isocyanate curing on standard and end-modified PGN.

We demonstrate photofragment emission with a compact fiber-laser source to measure gaseous HgCl2 concentration with the goal of developing a real-time stand-off speciating mercury emissions monitor. Assuming typical flue gas concentrations (74% N2, 12% CO2, 8% H2O, and 6% O2) at 200°C, we calculate a stand-off detection limit of 0.7 ppb for a fieldable monitoring instrument.

A class of planar, electrically-small UHF antennas suitable for direct integration with electronic components such as batteries is introduced. The new design approach combines a meander line section and a capacitive strip section. The geometries of the two sections can together be scaled in size over a wide range of planar form factors while still maintaining self-resonance and practically realizable line widths and spacings. No external matching network is required. Moreover, batteries can be mounted above or below the capacitive strip section, significantly reducing the total size of a wireless device. Three designs are demonstrated on printed circuit board at 433 MHz. Measurements show that the antennas provide good gain and excellent bandwidth, omnidirectional radiation patterns, and electrically small size. The results of this work have numerous uses in radiofrequency identification (RFID). © 2006 IEEE.

The development of tools and techniques for security testing and performance testing of Process Control Systems (PCS) is needed since those systems are vulnerable to the same classes of threats as other networked computer systems. In practice, security testing is difficult to perform on operational PCS because it introduces an unacceptable risk of disruption to the critical systems (e.g., power grids) that they control. In addition, the hardware used in PCS is often expensive, making full-scale mockup systems for live experiments impractical. A more flexible approach to these problems can be provided through test beds that provide the proper mix of real, emulated, and virtual elements to model large, complex systems such as critical infrastructures. This paper describes a "Virtual Control System Environment" that addresses these issues.

Risk consists of the likelihood of an event combined with the consequence ofthat event. There is uncertainty associated with an estimate of risk for an event that may happen in the future. For random, "dumb" events, such as an earthquake, this uncertainty is aleatory (stochastic) in nature and can be addressed with the probability measure of uncertainty. A terrorist act is not a random event; it is an intentional act by a thinking malevolent adversary. Much of the uncertainty in estimating the risk of a terrorist act is epistemic (state of knowledge); the adversary knows what acts will be attempted, but we as a defender have incomplete knowledge to know those acts with certainty. To capture the epistemic uncertainty in evaluating the risk from acts of terrorism, we have applied the belief/plausibility measure of uncertainty from the Dempster/Shafer Theory of Evidence. Also, to address how we as a defender evaluate the selection of scenarios by an adversary, we have applied approximate reasoning with fuzzy sets. We have developed software to perform these evaluations. © 2006 IEEE.

Increasing availability and decreasing prices of encryptors raise the question, "Can secure and regular network traffic be carried over one infrastructure?" If this is feasible without compromising the security of network data or attached systems, benefits in both money and reliability can be realized. This paper examines the trends in encryption hardware, presents a possible consolidated architecture, highlights potential benefits, and discusses obstacles and details that would need to be worked out before wide-spread adoption. © 2006 IEEE.

Abstract not provided.

Electroluminescence from self-assembled InAs quantum dots in cascade-like unipolar heterostructures is demonstrated. Initial results show weak luminescence signals in the mid-infrared from such structures, though more recent designs exhibit significantly stronger luminescence with improved designs of the active region of these devices. Further studies of mid-infrared emitting quantum dot structures have shown anisotropically polarized emission at multiple wavelengths. A qualitative explanation of such luminescence is developed and used to understand the growth morphology of buried quantum dots grown on AlAs layers. Finally, a novel design for future mid-infrared quantum dot emitters, intended to increase excited state scattering times and, at the same time, more efficiently extract carriers from the lowest states of our quantum dots, is presented,.

Genetic expression and control pathways can be successfully modeled as electrical circuits. To tackle large multicellular and genome scale simulations, the massively-parallel, electronic circuit simulator, Xyce™ [11], was adapted to address biological problems. Unique to this bio-circuit simulator is the ability to simulate not just one or a set of genetic circuits in a cell, but many cells and their internal circuits interacting through a common environment. Additionally, the circuit simulator Xyce can couple to the optimization and uncertainty analysis framework Dakota [2] allowing one to find viable parameter spaces for normal cell functionality and required parameter ranges for unknown or difficult to measure biological constants. Using such tools, we investigate the Drosophila sp. segmental differentiation network's stability as a function of initial conditions.

Hydrogen production from biomass has been paid more attention for years. Processes suggested for production of hydrogen from biomass are often involved in high-temperature pyrolysis[1-2], catalytic steam reforming [3] or enzymatic biosynthesis[4]. These strategies, however, encounter problems of high consumption of energy, low catalyst efficiency and very limited productivity. Group VIII metals such as Pt, Ni and Ru are more likely to be effective catalysts for reforming of oxygenated hydrocarbons (the main component in biomass), and among which, only Pt and Pd show both high activities and high selectivity for production of H 2[5-7]. Although lots of catalysts have been screened for this aqueous-phase reforming, the catalysts with high loadings noble metal such as platinum has to be used even when conducting at low feed concentration of 1 wt%[8]. Therefore, highly active catalytic materials need to be developed in order to render the process practical.

Abstract not provided.

Abstract not provided.

Abstract not provided.

Abstract not provided.

Abstract not provided.

Abstract not provided.

This minireview outlines the synthetic efforts, from our research group, to produce nanomaterials for use as imaging agents to study cell signaling pathways. An overview of our approach to the synthesis and biofunctionalization of metal, semiconductor, and ceramic nanomaterials is presented. The probes investigated include coinage metals, Cd-based, Geo, naturally occurring fluorescent (NOF) minerals, and Ln-based nanoparticles which were synthesized from novel metal alkoxide, amide, and alkyl precursors. We illustrate the applications of some of these materials as imaging probes to detect signaling pathway components and cellular responses to signals (apoptosis and degranulation) in inflammatory and cancer cells. © 2006 IEEE.

Abstract not provided.

Abstract not provided.

Monitoring programs for nuclear-waste repositories are now conceived as an exercise in performance confirmation: the purpose of the monitoring program is to provide objective evidence that the repository system is functioning as expected. However, monitoring is still largely seen as being entirely focused on the near-repository environment, with the aim of verifying predictions made about such things as temperature or rock mass behavior that are relevant to the designed functioning of the repository. A more comprehensive approach comes from recognizing that the repository is embedded in a larger natural system that may be affected by factors in addition to the repository. At some current or prospective repository sites, various human activities that are amenable to monitoring might potentially (or actually) affect the natural system. Observing these anthropogenically induced changes in the natural system and being able to simulate them accurately using the models already constructed for repository performance assessment provide an additional opportunity for performance confirmation. Water-level changes induced by oil and gas exploration and/or potash mining activities near the Waste Isolation Pilot Plant site provided an opportunity to confirm important features of the groundwater model used in performance assessment calculations. Repository programs should evaluate the potential for ongoing or future human activities to affect the systems in which their repositories are situated and provide an opportunity for performance confirmation.

We investigate the magnetostriction of field-structured magnetoelastomers, which are an important class of materials that have great potential as both sensors and actuators. Field-structured magnetoelastomers are synthesized by suspending magnetic particles in a polymeric resin and subjecting these to magnetic structuring fields during polymerization. These structuring fields can consist of as many as three orthogonal ac components, allowing a wide variety of particles structures-chains, sheets, or networks-to be formed. A principal issue is how particle structure and loading affects the magnetostriction of these materials. To investigate magnetostriction in these field-structured composites we have constructed a constant stress, optical cantilever apparatus capable of 1 ppm strain resolution. Magnetoelastomers having a wide range of particle loadings and structures are investigated, and it is shown that the observed deformation depends strongly on composite structure. The best magnetoelastomers exhibit a contractive strain of 10 000 ppm, the worst materials exhibit a negative, tensile response, which we show is due to the dominance of demagnetizing field effects over magnetostriction. Finally, some discussion is given to the surprising finding that magnetostriction is proportional to the sample prestrain. Simulations of a chain of particles in an elastomer show that particle clumping transitions can occur, but this does not account for the dependence of magnetostriction on prestrain. © 2006 The American Physical Society.

Removable polymer coatings were evaluated as a means to suppress dehydration of Alodine chromate conversion coatings during thermal aging and thereby retain the corrosion protection afforded by Alodine. Two types of polymer coatings were applied to Alodine-treated panels of aluminum alloys 7075-T73 and 6061-T6 that were subsequently aged for 15 to 50 hours at temperatures between 135 F to 200 F. The corrosion resistance of the thermally aged panels was evaluated, after stripping the polymer coatings, by exposure to a standard salt-fog corrosion test and the extent of pitting of the polymer-coated and untreated panels compared. Removable polymer coatings mitigated the loss of corrosion resistance due to thermal aging experienced by the untreated alloys. An epoxide coating was more effective than a fluorosilicone coating as a dehydration barrier.

Frictional contact results in surface and subsurface damage that could influence the performance, aging, and reliability of moving mechanical assemblies. Changes in surface roughness, hardness, grain size and texture often occur during the initial run-in period, resulting in the evolution of subsurface layers with characteristic microstructural features that are different from those of the bulk. The objective of this LDRD funded research was to model friction-induced microstructures. In order to accomplish this objective, novel experimental techniques were developed to make friction measurements on single crystal surfaces along specific crystallographic surfaces. Focused ion beam techniques were used to prepare cross-sections of wear scars, and electron backscattered diffraction (EBSD) and TEM to understand the deformation, orientation changes, and recrystallization that are associated with sliding wear. The extent of subsurface deformation and the coefficient of friction were strongly dependent on the crystal orientation. These experimental observations and insights were used to develop and validate phenomenological models. A phenomenological model was developed to elucidate the relationships between deformation, microstructure formation, and friction during wear. The contact mechanics problem was described by well-known mathematical solutions for the stresses during sliding friction. Crystal plasticity theory was used to describe the evolution of dislocation content in the worn material, which in turn provided an estimate of the characteristic microstructural feature size as a function of the imposed strain. An analysis of grain boundary sliding in ultra-fine-grained material provided a mechanism for lubrication, and model predictions of the contribution of grain boundary sliding (relative to plastic deformation) to lubrication were in good qualitative agreement with experimental evidence. A nanomechanics-based approach has been developed for characterizing the mechanical response of wear surfaces. Coatings are often required to mitigate friction and wear. Amongst other factors, plastic deformation of the substrate determines the coating-substrate interface reliability. Finite element modeling has been applied to predict the plastic deformation for the specific case of diamond-like carbon (DLC) coated Ni alloy substrates.

The probability of a laser caused ocular injury, to the aircrew of an undetected aircraft entering the exclusion zone about the AURA LIDAR airborne platform with the possible violation of the Laser Hazard Zone boundary, was investigated and quantified for risk analysis and management.

Piezoelectric polymers based on polyvinylidene fluoride (PVDF) are of interest as smart materials for novel space-based telescope applications. Dimensional adjustments of adaptive thin polymer films are achieved via controlled charge deposition. Predicting their long-term performance requires a detailed understanding of the piezoelectric property changes that develop during space environmental exposure. The overall materials performance is governed by a combination of chemical and physical degradation processes occurring in low Earth orbit as established by our past laboratory-based materials performance experiments (see report SAND 2005-6846). Molecular changes are primarily induced via radiative damage, and physical damage from temperature and atomic oxygen exposure is evident as depoling, loss of orientation and surface erosion. The current project extension has allowed us to design and fabricate small experimental units to be exposed to low Earth orbit environments as part of the Materials International Space Station Experiments program. The space exposure of these piezoelectric polymers will verify the observed trends and their degradation pathways, and provide feedback on using piezoelectric polymer films in space. This will be the first time that PVDF-based adaptive polymer films will be operated and exposed to combined atomic oxygen, solar UV and temperature variations in an actual space environment. The experiments are designed to be fully autonomous, involving cyclic application of excitation voltages, sensitive film position sensors and remote data logging. This mission will provide critically needed feedback on the long-term performance and degradation of such materials, and ultimately the feasibility of large adaptive and low weight optical systems utilizing these polymers in space.

Four Well-Characterized Open Pool fires were conducted by Fire Science and Technology Department. The focus of the Well-Characterized Open Pool fire series was to provide environmental information for open pool fires on a physics first principal basis. The experiments measured the burning rate of liquid fuel in an open pool and the resultant heat flux to a weapon-sized object and the surrounding environment with well-characterized boundary and initial conditions. Results presented in this report include a general description of test observation (pre- and post-test), wind measurements, fire plume topology, average fuel recession and heat release rates, and incident heat flux to the pool and to the calorimeters. As expected, results of the experiments show a strong correlation between wind conditions, fuel vaporization (mass loss) rate, and incident heat flux to the fuel and ground surface and calorimeters. Numerical fire simulations using both temporally- and spatially-dependant wind boundary conditions were performed using the Vulcan fire code. Comparisons of data to simulation predictions showed similar trends; however, simulation-predicted incident heat fluxes were lower than measured.

This report examines the localization of time harmonic high frequency modal fields in two dimensional cavities along periodic paths between opposing sides of the cavity. The cases where these orbits lead to unstable localized modes are known as scars. This paper examines the enhancements for these unstable orbits when the opposing mirrors are both convex and concave. In the latter case the construction includes the treatment of interior foci.

Establishing a Cartesian coordinate reference system for an existing Compact Antenna Range using the parabolic reflector is presented. A SMX (Spatial Metrix Corporation) M/N 4000 laser-based coordinate measuring system established absolute coordinates for the facility. Electric field characteristics with positional movement correction are evaluated. Feed Horn relocation for alignment with the reflector axis is also described. Reference points are established for follow-on non-laser alignments utilizing a theodolite.

Recent amendments to the Safe Drinking Water Act emphasize efforts toward safeguarding our nation's water supplies against attack and contamination. Specifically, the Public Health Security and Bioterrorism Preparedness and Response Act of 2002 established requirements for each community water system serving more than 3300 people to conduct an assessment of the vulnerability of its system to a terrorist attack or other intentional acts. Integral to evaluating system vulnerability is the threat assessment, which is the process by which the credibility of a threat is quantified. Unfortunately, full probabilistic assessment is generally not feasible, as there is insufficient experience and/or data to quantify the associated probabilities. For this reason, an alternative approach is proposed based on Markov Latent Effects (MLE) modeling, which provides a framework for quantifying imprecise subjective metrics through possibilistic or fuzzy mathematics. Here, an MLE model for water systems is developed and demonstrated to determine threat assessments for different scenarios identified by the assailant, asset, and means. Scenario assailants include terrorists, insiders, and vandals. Assets include a water treatment plant, water storage tank, node, pipeline, well, and a pump station. Means used in attacks include contamination (onsite chemicals, biological and chemical), explosives and vandalism. Results demonstrated highest threats are vandalism events and least likely events are those performed by a terrorist.

Three dimensional finite element analyses were performed to evaluate the structural integrity of the caverns located at the Bayou Choctaw (BC) site which is considered a candidate for expansion. Fifteen active and nine abandoned caverns exist at BC, with a total cavern volume of some 164 MMB. A 3D model allowing control of each cavern individually was constructed because the location and depth of caverns and the date of excavation are irregular. The total cavern volume has practical interest, as this void space affects total creep closure in the BC salt mass. Operations including both cavern workover, where wellhead pressures are temporarily reduced to atmospheric, and cavern enlargement due to leaching during oil drawdowns that use water to displace the oil from the caverns, were modeled to account for as many as the five future oil drawdowns in the six SPR caverns. The impacts on cavern stability, underground creep closure, surface subsidence, infrastructure, and well integrity were quantified.

Abstract not provided.

Abstract not provided.

Understanding the role of emotional states is critical for predicting the kind of decisions people will make in risky situations. Currently, there is little understanding as to how emotion influences decision-making in situations such as terrorist attacks, natural disasters, pandemics, and combat. To help address this, we used behavioral and neuroimaging methods to examine how emotion states and traits influence decisions. Specifically, this study used a wheel of fortune behavioral task and functional magnetic resonance imaging (fMRI) to examine the effects of emotional states and traits on decision-making pertaining to the degree of risk people are willing to make in specific situations. The behavioral results are reported here. The neural data requires additional time to analyze and will be reported at a future date. Biases caused by emotion states and traits were found regarding the likelihood of making risky decisions. The behavioral results will help provide a solid empirical foundation for modeling the effects of emotion on decision in risky situations.

Public mediated resource planning is quickly becoming the norm rather than the exception. Unfortunately, supporting tools are lacking that interactively engage the public in the decision-making process and integrate over the myriad values that influence water policy. In the pages of this report we document the first steps toward developing a specialized decision framework to meet this need; specifically, a modular and generic resource-planning ''toolbox''. The technical challenge lies in the integration of the disparate systems of hydrology, ecology, climate, demographics, economics, policy and law, each of which influence the supply and demand for water. Specifically, these systems, their associated processes, and most importantly the constitutive relations that link them must be identified, abstracted, and quantified. For this reason, the toolbox forms a collection of process modules and constitutive relations that the analyst can ''swap'' in and out to model the physical and social systems unique to their problem. This toolbox with all of its modules is developed within the common computational platform of system dynamics linked to a Geographical Information System (GIS). Development of this resource-planning toolbox represents an important foundational element of the proposed interagency center for Computer Aided Dispute Resolution (CADRe). The Center's mission is to manage water conflict through the application of computer-aided collaborative decision-making methods. The Center will promote the use of decision-support technologies within collaborative stakeholder processes to help stakeholders find common ground and create mutually beneficial water management solutions. The Center will also serve to develop new methods and technologies to help federal, state and local water managers find innovative and balanced solutions to the nation's most vexing water problems. The toolbox is an important step toward achieving the technology development goals of this center.

Control of nanoparticle size is crucial to the development of nanotechnology. At this point in time, no general, rational synthetic strategy for controlling nanocrystal diameters and producing narrow diameter distributions has emerged. This is a reflection of a poor understanding of the mechanisms for nanocrystal growth. Based on previous studies of bismuth and gold nanoparticle growth, this work clearly establishes two new synthetic approaches to controlled growth of colloidal Pt nanocrystals, both based on aggregative-growth mechanisms, which afford narrow size distributions and size control over a wide and relevant size regime. The first new method is a phase transfer process, where growth is controlled by varying ligand stabilizer concentrations. The second method involves rapid reduction of a molecular platinum precursor in the presence of a polymer stabilizer. At present the size control is empirical, and incompletely understood and incompletely developed. However, the new synthetic pathways are amenable to kinetic study and analysis, establishing that a quantitative, rational control of sizes and size distributions can be achieved.

The goal of this project was to develop a risk analysis meta tool--a tool that enables security analysts both to combine and analyze data from multiple other risk assessment tools on demand. Our approach was based on the innovative self-assembling software technology under development by the project team. This technology provides a mechanism for the user to specify his intentions at a very high level (e.g., equations or English-like text), and then the code self-assembles itself, taking care of the implementation details. The first version of the meta tool focused specifically in importing and analyzing data from Joint Conflict and Tactical Simulation (JCATS) force-on-force simulation. We discuss the problem, our approach, technical risk, and accomplishments on this project, and outline next steps to be addressed with follow-on funding.

Nonlinear FM (NLFM) waveforms offer a radar matched filter output with inherently low range sidelobes. This yields a 1-2 dB advantage in Signal-to-Noise Ratio over the output of a Linear FM (LFM) waveform with equivalent sidelobe filtering. This report presents details of processing NLFM waveforms in both range and Doppler dimensions, with special emphasis on compensating intra-pulse Doppler, often cited as a weakness of NLFM waveforms.

DEDICOM is a linear algebra model for analyzing intrinsically asymmetric relationships, such as trade among nations or the exchange of emails among individuals. DEDICOM decomposes a complex pattern of observed relations among objects into a sum of simpler patterns of inferred relations among latent components of the objects. Three-way DEDICOM is a higher-order extension of the model that incorporates a third mode of the data, such as time, giving it stronger uniqueness properties and consequently enhancing interpretability of solutions. In this paper, we present algorithms for computing these decompositions on large, sparse data as well as a variant for computing an asymmetric nonnegative factorization. When we apply these techniques to adjacency arrays arising from directed graphs with edges labeled by time, we obtain a smaller graph on latent semantic dimensions and gain additional information about their changing relationships over time. We demonstrate these techniques on the Enron email corpus to learn about the social networks and their transient behavior. The mixture of roles assigned to individuals by DEDICOM showed strong correspondence with known job classifications and revealed the patterns of communication between these roles. Changes in the communication pattern over time, e.g., between top executives and the legal department, were also apparent in the solutions.

Electronic components such as bipolar junction transistors (BJTs) are damaged when they are exposed to radiation and, as a result, their performance can significantly degrade. In certain environments the radiation consists of short, high flux pulses of neutrons. Electronics components have traditionally been tested against short neutron pulses in pulsed nuclear reactors. These reactors are becoming less and less available; many of them were shut down permanently in the past few years. Therefore, new methods using radiation sources other than pulsed nuclear reactors needed to be developed. Neutrons affect semiconductors such as Si by causing atomic displacements of Si atoms. The recoiled Si atom creates a collision cascade which leads to displacements in Si. Since heavy ions create similar cascades in Si we can use them to create similar damage to what neutrons create. This LDRD successfully developed a new technique using easily available particle accelerators to provide an alternative to pulsed nuclear reactors to study the displacement damage and subsequent transient annealing that occurs in various transistor devices and potentially qualify them against radiation effects caused by pulsed neutrons.

Abstract not provided.

This one year LDRD addressed the problem of rapid characterization of bacterial spores such as those from the genus Bacillus, the group that contains pathogenic spores such as B. anthracis. In this effort we addressed the feasibility of using a proteomics based approach to spore characterization using a subset of conserved spore proteins known as the small acid soluble proteins or SASPs. We proposed developing techniques that built on our previous expertise in microseparations to rapidly characterize or identify spores. An alternative SASP extraction method was developed that was amenable to both the subsequent fluorescent labeling required for laser-induced fluorescence detection and the low ionic strength requirements for isoelectric focusing. For the microseparations, both capillary isoelectric focusing and chip gel electrophoresis were employed. A variety of methods were evaluated to improve the molecular weight resolution for the SASPs, which are in a molecular weight range that is not well resolved by the current methods. Isoelectric focusing was optimized and employed to resolve the SASPs using UV absorbance detection. Proteomic signatures of native wild type Bacillus spores and clones genetically engineered to produce altered SASP patterns were assessed by slab gel electrophoresis, capillary isoelectric focusing with absorbance detection as well as microchip based gel electrophoresis employing sensitive laser-induced fluorescence detection.

We define a new diagnostic method where computationally-intensive numerical solutions are used as an integral part of making difficult, non-contact, nanometer-scale measurements. The limited scope of this report comprises most of a due diligence investigation into implementing the new diagnostic for measuring dynamic operation of Sandia's RF Ohmic Switch. Our results are all positive, providing insight into how this switch deforms during normal operation. Future work should contribute important measurements on a variety of operating MEMS devices, with insights that are complimentary to those from measurements made using interferometry and laser Doppler methods. More generally, the work opens up a broad front of possibility where exploiting massive high-performance computers enable new measurements.

This report summarizes our findings during the study of a novel system that yields multi-colored materials as products. This system is quite unusual as it leads to multi-chromic behavior in single crystals, where one would expect that only a single color would exist. We have speculated that these novel solids might play a role in materials applications such as non-linear optics, liquid crystal displays, piezoelectric devices, and other similar applications. The system examined consisted of a main-group alkyl compound (a p block element such as gallium or aluminum) complexed with various organic di-imines. The di-imines had substituents of two types--either alkyl or aromatic groups attached to the nitrogen atoms. We observed that single crystals, characterized by X-ray crystallography, were obtained in most cases. Our research during January-July, 2006, was geared towards understanding the factors leading to the multi-chromic nature of the complexes. The main possibilities put forth initially considered (a) the chiral nature of the main group metal, (b) possible reduction of the metal to a lower-valent, radical state, (c) the nature of the ligand(s) attached to the main group metal, and (d) possible degradation products of the ligand leading to highly-colored products. The work carried out indicates that the most likely explanation considered involves degradation of the aromatic ligands (a combination of (c) and (d)), as the experiments performed can clearly rule out (a) and (b).

Traditional cluster monitoring approaches consider nodes in singleton, using manufacturer-specified extreme limits as thresholds for failure ''prediction''. We have developed a tool, OVIS, for monitoring and analysis of large computational platforms which, instead, uses a statistical approach to characterize single device behaviors from those of a large number of statistically similar devices. Baseline capabilities of OVIS include the visual display of deterministic information about state variables (e.g., temperature, CPU utilization, fan speed) and their aggregate statistics. Visual consideration of the cluster as a comparative ensemble, rather than as singleton nodes, is an easy and useful method for tuning cluster configuration and determining effects of real-time changes.

A series of cerium alkoxides were synthesized from the reaction of Ce{N[Si(CH3)3]2}3 and the appropriate alcohol: neopentyl alcohol [H-OCH2C(CH3) 3 = H-ONep], tert-butyl alcohol [H-OC(CH3)3 = H-OtBu], o-(tert-butyl)phenol {H-OC6H4[C(CH 3)3]-2 = H-oBP), 2,6-dimethylphenol [H-OC 6H3(CH3)2-2,6 = H-DMP], 2,6-diisopropylphenol {H-OC6H3[CH(CH3) 2]2-2,6 = H-DIP}, 2,6-di-tert-butylphenol {H-OC 6H3[C(CH3)3]2-2,6 = H-DBP}, or 2,6-diphenylphenol [H-OC6H3(C6H 5)2-2,6 = H-DPP] using toluene (tol), tetrahydrofuran (THF) or pyridine (py). The precursors were characterized as [Ce(μ-ONep) 2(ONep)]4 (1), Ce4(μ3-OtBu) 3(μ-OtBu)4(OtBu)5 (2), Ce 3(μ3-OtBu)3(H-OtBu)2(OtBu) 3(H-OtBu)2 (2a), Ce(OBP)3(THF)3 (3), [Ce(μ-DMP)(DMP)2(solv)2]2 [solv = THF (4) and py (4a)], Ce(DIP)3(THF)3 (5), Ce(DPP) 3(THF)2 (6). Once isolated, several of these species were further reacted with a series of sterically varied carboxylic acid modifiers including isobutyric acid [H-O2CCH(CH3)2 = H-OPc] and trimethylacetic acid [H-O2CC(CH3)3 = H-OBc]. The products were isolated as [Ce(OR)(μ-ORc)(μc-ORc) (py)]2 [OR = oBP, OBc: 7; DMP, OPc: 8; DMP, OBc: 9; DIP, OPc: 10]. These compounds were identified by single-crystal X-ray diffraction and powder XRD analyses. Several novel structure types are added to the cerium alkoxide family of compounds. © Wiley-VCH Verlag GmbH & Co. KGaA, 2006.

Legacy plutonium-bearing materials are stored in shipping containers at the Savannah River Site (SRS) until their final disposition can be determined. This material has been stabilized and is maintained per the DOE’s standard for long-term storage of Pu-containing materials, DOE-STD-3013. As a part of its ongoing storage mission, Washington Savannah River Company’s (WSRC) Nuclear Materials Management (NMM) organization is tasked with a surveillance program that will ensure these materials have remained in their expected condition over the several years of storage. Information from this program will be used by multiple entities to further validate the safe storage of Pu-bearing materials per DOE-STD-3013. Part of the program entails cutting open selected 3013 containers and sampling the materials inside. These samples will then be analyzed by Savannah River National Laboratory (SRNL). The remaining material not used for samples will then be repackaged in non-3013 containers to be placed back into shipping packages for storage until disposition at SRS. These repackaged materials will be stored per the requirements of DOE’s Criteria for Interim Safe Storage of Plutonium Bearing Materials (ISSC).

The emission from a radiating source embedded in a photonic lattice is investigated. The photonic lattice spectrum was found to deviate from the blackbody distribution, with intracavity emission suppressed at certain frequencies and significantly enhanced at others. For rapid population relaxation, where the photonic lattice and blackbody populations are described by the same thermal distribution, it was found that the enhancement does not result in output intensities exceeding those of the blackbody. However, for slow population relaxation, the photonic lattice population has a greater tendency to deviate from thermal equilibrium, resulting in output intensities exceeding those of the blackbody.

In recent years, several researchers have constructed novel neural network models based on lattice algebra. Because of computational similarities to operations in the system of image morphology, these models are often called morphological neural networks. One neural model that has been successfully applied to many pattern recognition problems is the single-layer morphological perceptron with dendritic structure (SLMP). In this model, the fundamental computations are performed at dendrites connected to the body of a single neuron. Current training algorithms for the SLMP work by enclosing the target patterns in a set of hyperboxes orthogonal to the axes of the data space. This work introduces an alternate model of the SLMP, dubbed the synoptic morphological perceptron (SMP). In this model, each dendrite has one or more synapses that receive connections from inputs. The SMP can learn any region of space determined by an arbitrary configuration of hyperplanes, and is not restricted to forming hyperboxes during training. Thus, it represents a more general form of the morphological perceptron than previous architectures.

Elliptical crystal spectrometers equipped with time-gated microchannel plate (MCP) detectors provide time-, space-, and spectrally resolved data. A common problem is that the number of time resolution elements is limited by the number of MCP frames. The number of frames that fit on a given MCP is limited by the image size and the alignment tolerance. At the Z facility these problems have been addressed with twin-elliptical-crystal spectrometers. Using two crystals and detectors doubles the number of frames available. This enables measurements with ∼350 ps time resolution while still recording data from an ∼4 ns wide time window. Alternatively, the twin crystal design allows simultaneous measurements with different crystals to investigate different spectral regimes. © 2006 American Institute of Physics.

Using the physical process of ultraintense field ionization of high charge states of inert gas ions, we have developed a method of peak intensity measurement at the focus of high energy short pulse lasers operating in single shot mode. The technique involves detecting ionization products created from a low pressure gas target at the laser focus via time of flight detector. The observation of high ion charge states collected by the detector yields peak intensity at the focus when compared with the results obtained from well established tunnel ionization models. An initial peak intensity measurement of 5× 1016 W cm-2 was obtained for a 1.053 μm center wavelength, 0.4 J pulse with 1 ps pulse duration focused with an f5.5 off-axis parabola. Experiments with multijoule level, 500 fs laser pulses are on the way. © 2006 American Institute of Physics.

In optical firing sets, laser light is used to supply power to electronics (to charge capacitors, for example), to trigger electronics (such as vacuum switches), or in some cases, initiate explosives directly. Since MEMS devices combine electronics with electro-mechanical actuators, one can integrate safe and arm logic alongside the actuators to provide all functions in a single miniature package. We propose using MEMS-activated mirrors to make or break optical paths as part of the safe and arm architecture in an optical firing set. In the safe mode, a miniature (∼1 mm diameter) mirror is oriented to prevent completion of the optical path. To arm the firing set, the MEMS mirrors are deflected into the proper orientation thereby completing the optical path required for system functionality (e.g., light from a miniature laser completes the path to an optically triggered switch). The optical properties (i.e. damage threshold, reflectivity, transmission, absorption and scatter) of the miniature mirrors are critical to this application. Since Si is a strong absorber at the wavelengths under consideration (800 to 1064 nm), high-reflectivity, high-damage-threshold, dielectric coatings must be applied to the MEMS devices. In this paper we present conceptual MEMS-activated mirror architectures for performing arming and safing functions in an optical firing set and report test data which shows that dielectric coatings applied to MEMS-mirrors can withstand the prerequisite laser pulse irradiance. The measured optical damage threshold of polysilicon membranes with high-reflectivity multilayer dielectric coatings is ∼ 4 GW/cm 2, clearly demonstrating the feasibility of using coated MEMS mirrors in firing sets.

The LIGA microfabrication technique offers a unique method for fabricating 3-dimensional photonic lattices based on the Iowa State "logpile" structure. These structures represent the [111] orientation of the [100] logpile structures previously demonstrated by Sandia National Laboratories, The novelty to this approach is the single step process that does not require any alignment. The mask and substrate are fixed to one another and exposed twice from different angles using a synchrotron light source. The first exposure patterns the resist at an angle of 45 degrees normal to the substrate with a rotation of 8 degrees. The second exposure requires a 180 degree rotation about the normal of the mask and substrate. The resulting pattern is a vertically oriented logpile pattern that is rotated slightly off axis. The exposed PMMA is developed in a single step to produce an inverse lattice structure. This mold is filled with electroplated gold and stripped away to create a usable gold photonic crystal. Tilted logpiles demonstrate band characteristics very similar to those observed from [100] logpiles. Reflectivity tests show a band edge around 5 μm and compare well with numerical simulations.

The optical transfer of power is becoming important for military and industrial applications. The powering of electrical circuitry, sensors and actuators over optical fiber offers immunity from RF, EMI, voltage breakdown, lightning and high voltage hazards. Optical power transfer is being employed in industries such as electric power, communications, remote sensing, and aerospace. In this paper we address issues associated with the illumination of Series Connected Photovoltaic Arrays (SCPA). SCPAs are extremely sensitive to the uniformity of illumination. The performance of a photovoltaic array is dominated by the least illuminated cell. We introduce an analytical model that predicts the performance of a photovoltaic array for an arbitrary illumination. Experimental data on array performance is presented, and general issues associated with the problem of producing uniform illumination are discussed.

The use of photosensitive materials for the development of integrated, refractive-index structures supporting telecom, remote sensing, and varied optical beam manipulation applications is well established. Our investigations of photosensitive phenomena in polysilanes, however, have been motivated by the desire to configure, or program, the photonic device function immediately prior to use. Such an operational mode imposes requirements on wavelength sensitivity, incident fluence and environmental conditions that are not typical of more conventional applications of photosensitive material. The present paper focuses on our efforts to understand and manipulate photosensitivity in polysilane thin films under different excitation wavelengths, local atmospheric compositions and thermal history in this context. We find that the photoresponse can be influenced through the control of such optical exposure conditions, thereby influencing the magnitude of the photoinduced refractive-index change attained.

Biochemical reactions taking place in living systems that map different inputs to specific outputs are intuitively recognized as performing information processing. Conventional wisdom distinguishes such proteins, whose primary function is to transfer and process information, from proteins that perform the vast majority of the construction, maintenance, and actuation tasks of the cell (assembling and disassembling macromolecular structures, producing movement, and synthesizing and degrading molecules). In this paper, we examine the computing capabilities of biological processes in the context of the formal model of computing known as the random access machine (RAM) [Dewdney AK (1993) The New Turing Omnibus. Computer Science Press, New York], which is equivalent to a Turing machine [Minsky ML (1967) Computation: Finite and Infinite Machines. Prentice-Hall, Englewood Cliffs, NJ]. When viewed from the RAM perspective, we observe that many of these dynamic self-assembly processes - synthesis, degradation, assembly, movement - do carry out computational operations. We also show that the same computing model is applicable at other hierarchical levels of biological systems (e.g., cellular or organism networks as well as molecular networks). We present stochastic simulations of idealized protein networks designed explicitly to carry out a numeric calculation. We explore the reliability of such computations and discuss error-correction strategies (algorithms) employed by living systems. Finally, we discuss some real examples of dynamic self-assembly processes that occur in living systems, and describe the RAM computer programs they implement. Thus, by viewing the processes of living systems from the RAM perspective, a far greater fraction of these processes can be understood as computing than has been previously recognized. © Springer Science+Business Media, Inc. 2006.

Electron beam welding is a well known process used where high precision, high reliability welds are needed, often in exotic materials. Recently, it has been proposed to apply the electron beam produced in a standard scanning electron microscope (SEM), with reversible modifications to increase beam current, for microscale welding. In addition to providing the clean environment associated with the column vacuum, the SEM in imaging mode provides exceptional capabilities in visualising extremely small parts. Furthermore, the standard stage and beam motion controls offer the possibility of flexible programming of beam path with relatively minor software additions. In order to better evaluate the requirements for and effects of μE-beam welding (μEBW) on typical microtechnologically important materials, a clear understanding of the characteristics of the SEM's beam and its interaction with possible target materials is needed. The penetration ability of electrons depends strongly upon their accelerating voltage and the target they are being directed at. Hence, in some circumstances the beam may interact as a surface heat source, while in others it may act as a volume heat source, with important consequences on weld schedule development for the parts and geometry being welded. In this work, the authors explore some of the factors involved and propose simple models for the electron beam heat source which depend on the parameters being used. © 2006 Institute of Materials, Minerals and Mining.

Instrumented indentation was combined with microscopy and spectroscopy analysis to investigate the local mechanically induced ferroelectric to anti-ferroelectric phase transformation of niobium-modified lead zirconate titanate 95/5. Indentation experiments to a depth of 2 μm were performed using a Berkovich pyramidal three-sided diamond tip. Subsequent Raman spectroscopy and piezoelectric force microscopy revealed that indentation locally induced the ferroelectric to antiferroelectric phase transformation. Piezoelectric force microscopy demonstrated the ability to map the individual phases within and near indented regions on the niobium-modified lead zirconate titanate ceramics. © 2006 The American Ceramic Society.

The energy output of the high-level radioactive waste to be emplaced in the proposed geologic repository at Yucca Mountain, NV, will strongly affect the thermal-hydrological (TH) conditions in the near-drift fractured rock. Heating of rock water to above-boiling conditions will induce large water saturation changes and flux perturbations close to the waste emplacement tunnels (drifts) that will last several thousand years. Understanding these perturbations is important for the performance of the repository, because they could increase, for example, the amount of formation water seeping into the open drifts and contacting waste packages. Recent computational fluid dynamics analysis has demonstrated that the drifts will act as important conduits for gas flows driven by natural convection. As a result, vapor generated from boiling of formation water near elevated-temperature sections of the drifts may effectively be transported to cooler end sections (where no waste is emplaced), where it would condense and subsequently drain into underlying rock units. Thus, natural convection processes have great potential for reducing the near-drift moisture content in heated drift sections, which has positive ramifications for repository performance. To study these processes, we have developed a new simulation method that couples existing tools for simulating TH conditions in the fractured formation with modules that approximate natural convection and evaporation conditions in heated emplacement drifts. The new method is applied to evaluate the impact of in-drift natural convection on the future TH conditions at Yucca Mountain in a three-dimensional model domain comprising a representative emplacement drift and the surrounding fractured rock. © Soil Science Society of America.

Interest in the analysis of random vibrations of mechanical systems started to grow about a half century ago in response to the need for a theory that could accurately predict structural response to jet engine noise and missile launch-induced environments. However, the work that enabled development of the theory of random vibrations started about a half century earlier. This paper discusses contributions to the theory of random vibrations from the time of Einstein to the time of an MIT workshop that was organized by Crandall in 1958. © 2006 Elsevier Ltd. All rights reserved.

Abstract not provided.

Abstract not provided.

Abstract not provided.

Abstract not provided.

Abstract not provided.

Abstract not provided.