Voltage and temperature distributions along the crucible were measured during VAR of 0.81 m diameter Ti-6Al-4V electrode into 0.91 m diameter ingot. These data were used to determine the current distribution along the crucible. Measurements were made for two furnace conditions, one with a bare crucible and the other with a painted crucible. The VAR furnace used for these measurements is of the non-coaxial type, i.e. current is fed directly into the bottom of the crucible through a stool (base plate) contact and exits the furnace through the electrode stinger. The data show that approximately 63% of the current is conducted directly between the ingot and electrode with the remaining conducted between the electrode and crucible wall. This partitioning does not appear to be sensitive to crucible coating. The crucible voltage data were successfully simulated using uniform current distributions for the current conduction zones, a value of 0.63 for the partitioning, and widths of 0.30 and 0.15 m for the ingot/crucible wall and plasma conduction zones, respectively. Successful simulation of the voltage data becomes increasingly difficult (or impossible) as one uses current partitioning values increasingly different from 0.63, indicating that the experimental value is consistent with theory. Current conducted between the ingot and crucible wall through the ingot/wall contact zone may vary during the process without affecting overall current partitioning. The same is true for current conducted through the ingot/stool and stool/crucible contact zones. There is some evidence that the ingot/stool current decreases with increasing ingot length for the case of the bare crucible. Equivalent circuit analysis shows that, under normal conditions, current partitioning is only sensitive to the ratio of the plasma resistance across the annulus to the plasma resistance across the electrode gap, thereby demonstrating the relationship between current partitioning and gap.
Our charter at Sandia National Laboratories is to develop technology to reduce the development cost of geothermal drilling. Due to their aggressive penetration rate performance, Polycrystalline Diamond Compact (PDC) bits are of particular interest for this application and they have recently been demonstrated to be capable of drilling hard-rock formations characteristic of geothermal reservoirs. Additionally, oil and gas operators are increasingly forced to extend their drilling targets to include these hard-rock formations as our fossil energy reserves dwindle. However, PDC bits are particularly susceptible to impact-type damage due to the onset of drilling vibrations that can cause bit failure. Bit vibration produces an undulated surface in the rock that in turn produces a time-variant force that feeds back into the vibration of the bit and drillstring. While there is considerable debate in the drilling community regarding the relative significance of the various types of vibrations, self-induced vibrations do occur and can be mathematically predicted if the drill bit, drillstring, and rock type are not correctly matched. One way to alleviate this problem is to insert a vibration absorber into the drillstring. Given the broad range of parameters contributing to bit vibrations, any damper installed in the drillstring should be controllable to give it more dynamic range. We have experimentally demonstrated that a controllable damper can introduce stability in PDC bits drilling hard rock typical of geothermal formations.
Proceedings of the Solar World Congress 2005: Bringing Water to the World, Including Proceedings of 34th ASES Annual Conference and Proceedings of 30th National Passive Solar Conference
Begay-Campbell, Sandra; Coots, Jennifer; Mar, Benjamin
Sandia National Laboratories (Sandia) has an active relationship with the Navajo Nation. Sandia has grown this relationship with through joint formation of strategic multiyear plans oriented toward the development of sustainable Native American renewable energy projects and associated business development. For the last decade, the Navajo Tribal Utility Authority (NTUA) has installed stand-alone photovoltaic (PV) systems on the Navajo Reservation to provide some of its most remote customers with electricity. Sandia and New Mexico State University - Southwest Technology Development Institute's technical assistance supports NTUA as a leader in rural solar electrification, assists NTUA's solar program coordinator to create a sustainable program and conveys NTUA's success in solar to others, including the Department of Energy (DOE). In partnership with DOE's Tribal Energy Program, summer interns' Jennifer Coots (MBA student) and Benjamin Mar (Electrical and Computer Engineering student) prepared case studies that summarize the rural utility's experience with solar electric power.
LMPC 2005 - Proceedings of the 2005 International Symposium on Liquid Metal Processing and Casting
Viswanathan, Srinath; Melgaard, David K.; Patel, Ashish D.; Evans, David G.
A numerical model of the ESR process was used to study the effect of the various process parameters on the resulting temperature profiles, flow field, and pool shapes. The computational domain included the slag and ingot, while the electrode, crucible, and cooling water were considered as external boundary conditions. The model considered heat transfer, fluid flow, solidification, and electromagnetic effects. The predicted pool profiles were compared with experimental results obtained over a range of processing parameters from an industrial-scale 718 alloy ingot. The shape of the melt pool was marked by dropping nickel balls down the annulus of the crucible during melting. Thermocouples placed in the electrode monitored the electrode and slag temperature as melting progressed. The cooling water temperature and flow rate were also monitored. The resulting ingots were sectioned and etched to reveal the ingot macrostructure and the shape of the melt pool. Comparisons of the predicted and experimentally measured pool profiles show excellent agreement. The effect of processing parameters, including the slag cap thickness, on the temperature distribution and flow field are discussed. The results of a sensitivity study of thermophysical properties of the slag are also discussed.
The structural characteristics of buttress thread mechanical joints are not well understood and are difficult to accurately model. As an initial step towards understanding the mechanics of the buttress thread, a 2D plane stress model was created. An experimental investigation was conducted to study the compliance, damping characteristics, and stress field in an axial test condition. The compliance and damping were determined experimentally from a steel cross section of a buttress thread. The stress field was visualized using photoelastic techniques. The mechanics study combined with the photoelastic study provided a set of validation data.
In this paper, we discuss the primary characteristics and pitfalls associated with the use of Bragg Gratings for distributed temperature sensing, with particular attention to time-division multiplexing (TDM). Two pitfalls are intrinsic to a serial array of such gratings that use TDM: spectral shadowing and crosstalk. Two others involve strain in the fiber that masquerades as temperature and that could affect other methods of interrogating the gratings, in addition to TDM.
LMPC 2005 - Proceedings of the 2005 International Symposium on Liquid Metal Processing and Casting
Minisandram, Ramesh S.; Arnold, Matthew J.; Williamson, Rodney L.
During VAR of a 5377 kg, 0.76 m diameter Ti-6Al-4V alloy electrode into 0.86 m diameter ingot, tantalum balls were dropped into the ingot pool to measure the centerline pool depth. The first was introduced at full power after 1134 kg of electrode had been melted. A second marker was dropped after 4288 kg of electrode had been consumed, also at full power but just prior to power cutback. The third, and final, ball was released at the end of the cutback with 286 kg of electrode remaining. An external solenoidal stirring field was applied to the ingot throughout the melting process, as is typical in such practices. The ingot was sectioned, the marker ball positions recorded, and the pool depths subsequently calculated. The first market was located only 4.5 cm from the bottom of the ingot, but was off-center by nearly 22 cm, indicating a relatively flat pool bottom. The other two balls were located 36.2 cm and 105.4 cm from the bottom, both approximately centered. Pool depths for the three conditions were calculated to be ∼41 cm, ∼131 cm and ∼99 cm. BAR, a 21/2 D, axisymmetric ingot code developed at Sandia National Laboratories, was used to generate pool shapes corresponding to these conditions. The code, which solves heat transfer, fluid flow and electromagnetic effects in a coupled fashion, was able to match the pool depths by adjusting the strength of the stirring field as a parameter, and predicted relatively thin sidewalls under full power melting, a prediction supported by crucible temperature and current distribution data also collected during the test. The applied stirring field was 60 gauss for this test. The effective field strength setting in BAR required to match the pool depths was 30 gauss. All other parameters in BAR were set identical to those required to match low stirring field (4 gauss), full power ingot pool depths measured and reported in an earlier study, except those requiring consistency with observed arc behavior in the two cases. Thus, it is concluded that the 21/2 D code can accurately match pool depths under high field strength stirring conditions once properly benchmarked.
ICEAA 2005 - 9th International Conference on Electromagnetics in Advanced Applications and EESC 2005 - 11th European Electromagnetic Structures Conference
Simulation results demonstrating transmission enhancement through a sub-wavelength aperature in an infinite plasmon array are presented. The results are obtained using EIGER and are considered preliminary before proceeding to the simulation of finite-plasmon arrays.
Grain boundary stiffness and mobility determine the kinetics of curvature driven grain growth. Here the stiffness and mobility are determined using a computational approach based on the analysis of fluctuations in the grain boundary position during molecular dynamics simulations. This work represents the first determination of grain boundary stiffness. The results indicate that the boundary stiffness for a given boundary plane has a strong dependence on the direction of the boundary distortion. The mobility deduced is in accord with previous computer simulation studies.
Engineering/Technology Management 2005: Safety Engineering and Risk Analysis, Technology and Society, Engineering Business Management, Health and Safety
Lloyd, George M.; Hasselman, Timothy; Paez, Thomas
CMMs equipped with non-contact probes, such as video probes, are becoming popular for a variety of 2-D or 2.5-D objects. The advantages of a video (or vision) probe include the ability to measure features which are either too small or too delicate for a touch probe. Unfortunately, vision-based probing systems do not have the same measurement accuracy as touch probe equipped machines. For example, a Moore M48 coordinate measurement machine has an expected measurement uncertainty of 0.2 μm (plus a scale dependent term) when using a touch probe (the actual repeatability is on the order of 0.03 μm). When the probe is changed to a Leitz LS1 vision system, the expected measurement uncertainty is 1.2 μm plus a scale dependent term. The decreased accuracy is due entirely to the change in probing method. Components of the error budget include environmental effects, choice of lighting, lens distortions, and stage 2-D accuracy. Lighting is a major contributor to the measurement error budget, especially when a bidirectional measurement needs to be made (for example, the width of a line, rather than the center location of a line). We report on the effect of the sensitivity of vision probing on an OGP Avant Apex 200 to different lighting conditions, both for unidirectional and bidirectional measurements.
Sandia National Laboratories has developed a mesoscale wheeled hopping vehicle (WHV) to overcome the longstanding problems of mobility and power in small scale unmanned vehicles. The system provides mobility in situations such as negotiating obstacles in the vertical dimension and rough terrain that are prohibitive for other small ground base vehicles.
Sandia National Laboratories (SNL) has limited inventories of, and activities with, fissile-material. Personnel who perform nuclear criticality safety (NCS) assignments do so on a part-time basis. Sandia's "tailored approach" to training and qualification of these personnel can serve as a model for others with "small" NCS programs. SNL uses a single set of qualification cards for qualifying nuclear criticality safety engineers (NCSE). Provision is made for: (1) training and mentoring of new NCSE with testing or other verification of their skills and knowledge and (2) "qualification by documentation" for staff who historically have been performing NCSE-like duties. Key areas for evaluation include previous formal education and training; demonstrated success in writing Criticality Safety Assessments (CSA) and related documents; interaction with the SNL criticality safety committees; and overall knowledge (e.g., as judged against the objectives in DOE-STD-1135). Gaps of knowledge are filled through self-study, training, or mentoring. Candidate mastery of topics is confirmed primarily by evaluation of work products and interviews. Completion is approved by the Criticality Safety Officer (CSO) - the closest SNL comes to having an NCS manager - and then management. In applying the tailored approach, NCSE candidates are not required to be subject-matter experts for all NCS-related facilities and activities at SNL at the time of qualification. Familiarity with each of the facilities and activities is expected, along with the ability to "self-train" when needed (e.g., analogous just-in-time [JIT] procurement). The latter is supported by identification of applicable SNL-wide fissile-material facilities and activities along with resource organizations and personnel in NCS, safety analysis, accountability, etc. The capstone is a discussion with the CSO, or other experienced NCSE, demonstrating the ability to explain in some detail how a specific NCS assignment would be tackled (e.g., options for gaining facility/activity knowledge, performing analyses, using resource personnel, and traversing the required peer- and committee-review processes).
In this paper, we describe what we believe to be the characteristics of the collaborations required in the domain of critical infrastructure modeling, based on our experiences to date. We adopt a knowledge management philosophy, which imposes two classes of requirements, contextual who, when, and why), and semantic what interactions are conducted around). We observe that infrastructure models can often engender more insight when used as the basis for a meaningful discussion between the disparate stakeholder groups (private industry, trade organizations, industry lobbying groups, etc.) than when exercised computationally.
The human brain functions through a chemically-induced biological process which operates in a manner similar to electrical systems. The signal resulting from this biochemical process can actually be monitored and read using tools and having patterns similar to those found in electrical and electronics engineering. The primary signature of this electrical activity is the ''brain wave'', which looks remarkably similar to the output of many electrical systems. Likewise, the device currently used in medical arenas to read brain electrical activity is the electroencephalogram (EEG) which is synonymous with a multi-channel oscilloscope reading. Brain wave readings and recordings for medical purposes are traditionally taken in clinical settings such as hospitals, laboratories or diagnostic clinics. The signal is captured via externally applied scalp electrodes using semi-viscous gel to reduce impedance. The signal will be in the 10 to 100 microvolt range. In other instances, where surgeons are attempting to isolate particular types of minute brain signals, the electrodes may actually be temporarily implanted in the brain during a preliminary procedure. The current configurations of equipment required for EEGs involve large recording instruments, many electrodes, wires, and large amounts of hard disk space devoted to storing large files of brain wave data which are then eventually analyzed for patterns of concern. Advances in sensors, signal processing, data storage and microelectronics over the last decade would seem to have paved the way for the realization of devices capable of ''real time'' external monitoring, and possible assessment, of brain activity. A myriad of applications for such a capability are likewise presenting themselves, including the ability to assess brain functioning, level of functioning and malfunctioning. Our plan is to develop the sensors, signal processing, and portable instrumentation package which could capture, analyze, and communicate information on brain activity which could be of use to the individual, medical personnel or in other potential arenas. To take this option one step further, one might foresee that the signal would be captured, analyzed, and communicated to a person or device and which would result an action or reaction by that person or device. It is envisioned that ultimately a system would include a sensor detection mechanism, transmitter, receiver, microprocessor and associated memory, and audio and/or visual alert system. If successful in prototyping, the device could be considered for eventual implementation in ASIC form or as a fully integrated CMOS microsystem.
The production of Ultra-cold molecules is a goal of many laboratories through out the world. Here we are pursuing a unique technique that utilizes the kinematics of atomic and molecular collisions to achieve the goal of producing substantial numbers of sub Kelvin molecules confined in a trap. Here a trap is defined as an apparatus that spatially localizes, in a known location in the laboratory, a sample of molecules whose temperature is below one degree absolute Kelvin. Further, the storage time for the molecules must be sufficient to measure and possibly further cool the molecules. We utilize a technique unique to Sandia to form cold molecules from near mass degenerate collisions between atoms and molecules. This report describes the progress we have made using this novel technique and the further progress towards trapping molecules we have cooled.
The purpose of this project was to do some preliminary studies and process development on electroactive polymers to be used for tunable optical elements and MEMS actuators. Working in collaboration between Sandia National Labs and The University of Illinois Urbana-Champaign, we have successfully developed a process for applying thin films of poly (vinylidene fluoride) (PVDF) onto glass substrates and patterning these using a novel stamping technique. We observed actuation in these structures in static and dynamic measurements. Further work is needed to characterize the impact that this approach could have on the field of tunable optical devices for sensing and communication.
This Pollution Prevention Opportunity Assessment (PPOA) was conducted for the two Sandia National Laboratories/New Mexico cafeteria facilities between May and August 2005. The primary purpose of this PPOA is to assess waste and resource reduction opportunities and issue Pollution Prevention (P2) recommendations for Sandia's food service facilities. This PPOA contains recommendations for energy, water and resource reduction, as well as material substitution based upon environmentally preferable purchasing. Division 3000 has requested the PPOA report as part of the Division's compliance effort to implement the Environmental Management System (EMS) per DOE Order 450.1. This report contains a summary of the information collected and analyses performed with recommended options for implementation. The SNL/NM P2 Group will work with Division 3000 and the respective cafeteria facilities to implement these options.
Red Storm is an Advanced Simulation and Computing (ASC) funded massively parallel supercomputer located at Sandia National Laboratories (SNL). The Red Storm Usage Model (RSUM) documents the capabilities and the environment provided for the FY05 Tri-Lab Level II Limited Availability Red Storm User Environment Milestone and the FY05 SNL Level II Limited Availability Red Storm Platform Milestone. This document describes specific capabilities, tools, and procedures to support both local and remote users. The model is focused on the needs of the ASC user working in the secure computing environments at Los Alamos National Laboratory (LANL), Lawrence Livermore National Laboratory (LLNL), and SNL. Additionally, the Red Storm Usage Model maps the provided capabilities to the Tri-Lab ASC Computing Environment (ACE) requirements. The ACE requirements reflect the high performance computing requirements for the ASC community and have been updated in FY05 to reflect the community's needs. For each section of the RSUM, Appendix I maps the ACE requirements to the Limited Availability User Environment capabilities and includes a description of ACE requirements met and those requirements that are not met in that particular section. The Red Storm Usage Model, along with the ACE mappings, has been issued and vetted throughout the Tri-Lab community.
Focused Beams from high-power lasers have been used to command trigger gas switches in pulse power accelerators for more than two decades. This Laboratory-Directed Research and Development project was aimed at determining whether high power lasers could also command trigger water switches on high-power accelerators. In initial work, we determined that focused light from three harmonics of a small pulsed Nd:YAG laser at 1064 nm, 532 nm, and 355 nm could be used to form breakdown arcs in water, with the lowest breakdown thresholds of 110 J/cm{sup 2} or 14 GW/cm{sup 2} at 532 nm in the green. In laboratory-scale laser triggering experiments with a 170-kV pulse-charged water switch with a 3-mm anode-cathode gap, we demonstrated that {approx}90 mJ of green laser energy could trigger the gap with a 1-{sigma} jitter of less than 2ns, a factor of 10 improvement over the jitter of the switch in its self breaking mode. In the laboratory-scale experiments we developed optical techniques utilizing polarization rotation of a probe laser beam to measure current in switch channels and electric field enhancements near streamer heads. In the final year of the project, we constructed a pulse-power facility to allow us to test laser triggering of water switches from 0.6- MV to 2.0 MV. Triggering experiments on this facility using an axicon lens for focusing the laser and a switch with a 740 kV self-break voltage produced consistent laser triggering with a {+-} 16-ns 1-{sigma} jitter, a significant improvement over the {+-} 24-ns jitter in the self-breaking mode.
Over the past few years we have developed the ability to acquire images through a confocal microscope that contain, for each pixel, the simultaneous fluorescence lifetime and spectra of multiple fluorophores within that pixel. We have demonstrated that our system has the sensitivity to make these measurements on single molecules. The spectra and lifetimes of fluorophores bound to complex molecules contain a wealth of information on the conformational dynamics and local chemical environments of the molecules. However, the detailed record of spectral and temporal information our system provides from fluorophores in single molecules has not been previously available. Therefore, we have studied several fluorophores and simple fluorophore-molecule systems that are representative of the use of fluorophores in biological systems. Experiments include studies of a simple fluorescence resonance energy transfer (FRET) system, green fluorescent probe variants and quantum dots. This work is intended to provide a basis for understanding how fluorophores report on the chemistry of more complex biological molecules.
The goal of this project was to develop novel hydrogen-oxidation electrocatalyst materials that contain reduced platinum content compared to traditional catalysts by developing flexible synthesis techniques to fabricate supported catalyst structures, and by verifying electrochemical performance in half cells and ultimately laboratory fuel cells. Synthesis methods were developed for making small, well-defined platinum clusters using zeolite hosts, ion exchange, and controlled calcination/reduction processes. Several factors influence cluster size, and clusters below 1 nm with narrow size distribution have been prepared. To enable electrochemical application, the zeolite pores were filled with electrically-conductive carbon via infiltration with carbon precursors, polymerization/cross-linking, and pyrolysis under inert conditions. The zeolite host was then removed by acid washing, to leave a Pt/C electrocatalyst possessing quasi-zeolitic porosity and Pt clusters of well-controlled size. Plotting electrochemical activity versus pyrolysis temperature typically produces a Gaussian curve, with a peak at ca. 800 C. The poorer relative performances at low and high temperature are due to low electrical conductivity of the carbon matrix, and loss of zeolitic structure combined with Pt sintering, respectively. Cluster sizes measured via adsorption-based methods were consistently larger than those observed by TEM and EXAFS, suggesting , that a fraction of the clusters were inaccessible to the fluid phase. Detailed EXAFS analysis has been performed on selected catalysts and catalyst precursors to monitor trends in cluster size evolution, as well as oxidation states of Pt. Experiments were conducted to probe the electroactive surface area of the Pt clusters. These Pt/C materials had as much as 110 m{sup 2}/g{sub pt} electroactive surface area, an almost 30% improvement over what is commercially (mfg. by ETEK) available (86 m{sup 2}/g{sub pt}). These Pt/C materials also perform qualitatively as well as the ETEK material for the ORR, a non-trivial achievement. A fuel cell test showed that Pt/C outperformed the ETEK material by an average of 50% for a 300 hour test. Increasing surface area decreases the amount of Pt needed in a fuel cell, which translates into cost savings. Furthermore, the increased performance realized in the fuel cell test might ultimately mean less Pt is needed in a fuel cell; this again translates into cost savings. Finally, enhanced long-term stability is a key driver within the fuel cell community as improvements in this area must be realized before fuel cells find their way into the marketplace; these Pt/C materials hold great promise of enhanced stability over time. An external laser desorption ion source was successfully installed on the existing Fourier transform ion-cyclotron resonance (FT-ICR) mass spectrometer. However, operation of this laser ablation source has only generated metal atom ions, no clusters have been found to date. It is believed that this is due to the design of the pulsed-nozzle/laser vaporization chamber. The final experimental configuration and design of the two source housings are described.
The ability of semiconductor nanocrystals (NCs) to display multiple (size-specific) colors simultaneously during a single, long term excitation holds great promise for their use in fluorescent bio-imaging. The main challenges of using nanocrystals as biolabels are achieving biocompatibility, low non-specific adsorption, and no aggregation. In addition, functional groups that can be used to further couple and conjugate with biospecies (proteins, DNAs, antibodies, etc.) are required. In this project, we invented a new route to the synthesis of water-soluble and biocompatible NCs. Our approach is to encapsulate as-synthesized, monosized, hydrophobic NCs within the hydrophobic cores of micelles composed of a mixture of surfactants and phospholipids containing head groups functionalized with polyethylene glycol (-PEG), -COOH, and NH{sub 2} groups. PEG provided biocompatibility and the other groups were used for further biofunctionalization. The resulting water-soluble metal and semiconductor NC-micelles preserve the optical properties of the original hydrophobic NCs. Semiconductor NCs emit the same color; they exhibit equal photoluminescence (PL) intensity under long-time laser irradiation (one week) ; and they exhibit the same PL lifetime (30-ns). The results from transmission electron microscopy and confocal fluorescent imaging indicate that water-soluble semiconductor NC-micelles are biocompatible and exhibit no aggregation in cells. We have extended the surfactant/lipid encapsulation techniques to synthesize water-soluble magnetic NC-micelles. Transmission electron microscopy results suggest that water-soluble magnetic NC-micelles exhibit no aggregation. The resulting NC-micelles preserve the magnetic properties of the original hydrophobic magnetic NCs. Viability studies conducted using yeast cells suggest that the magnetic nanocrystal-micelles are biocompatible. We have demonstrated, for the first time, that using external oscillating magnetic fields to manipulate the magnetic micelles, we can kill live cells, presenting a new magnetodynamic therapy without side effects.
The objective of this report is to develop uncertainty estimates for three heat flux measurement techniques used for the measurement of incident heat flux in a combined radiative and convective environment. This is related to the measurement of heat flux to objects placed inside hydrocarbon fuel (diesel, JP-8 jet fuel) fires, which is very difficult to make accurately (e.g., less than 10%). Three methods will be discussed: a Schmidt-Boelter heat flux gage; a calorimeter and inverse heat conduction method; and a thin plate and energy balance method. Steady state uncertainties were estimated for two types of fires (i.e., calm wind and high winds) at three times (early in the fire, late in the fire, and at an intermediate time). Results showed a large uncertainty for all three methods. Typical uncertainties for a Schmidt-Boelter gage ranged from {+-}23% for high wind fires to {+-}39% for low wind fires. For the calorimeter/inverse method the uncertainties were {+-}25% to {+-}40%. The thin plate/energy balance method the uncertainties ranged from {+-}21% to {+-}42%. The 23-39% uncertainties for the Schmidt-Boelter gage are much larger than the quoted uncertainty for a radiative only environment (i.e ., {+-}3%). This large difference is due to the convective contribution and because the gage sensitivities to radiative and convective environments are not equal. All these values are larger than desired, which suggests the need for improvements in heat flux measurements in fires.
This guide describes the R&A process, Common Look and Feel requirements, and preparation and publishing procedures for communication products at Sandia National Laboratories. Samples of forms and examples of published communications products are provided. This guide details the processes for producing a variety of communication products at Sandia National Laboratories. Figure I-1 shows the general publication development process. Because extensive supplemental material is available from Sandia on the internal Web or from external sources (Table I-1), the guide has been shortened to make it easy to find information that you need.
Flexible Alternating Current Transmission Systems (FACTS) devices are installed on electric power transmission lines to stabilize and regulate power flow. Power lines protected by FACTS devices can increase power flow and better respond to contingencies. The University of Missouri Rolla (UMR) is currently working on a multi-year project to examine the potential use of multiple FACTS devices distributed over a large power system region in a cooperative arrangement in which the FACTS devices work together to optimize and stabilize the regional power system. The report describes operational and security challenges that need to be addressed to employ FACTS devices in this way and recommends references, processes, technologies, and policies to address these challenges.
This one year LDRD addresses problems of threat assessment and restoration of facilities following a bioterror incident like the incident that closed down mail facilities in late 2001. Facilities that are contaminated with pathogenic spores such as B. anthracis spores must be shut down while they are treated with a sporicidal agent and the effectiveness of the treatment is ascertained. This process involves measuring the viability of spore test strips, laid out in a grid throughout the facility; the CDC accepted methodologies require transporting the samples to a laboratory and carrying out a 48 hr outgrowth experiment. We proposed developing a technique that will ultimately lead to a fieldable microfluidic device that can rapidly assess (ideally less than 30 min) spore viability and effectiveness of sporicidal treatment, returning facilities to use in hours not days. The proposed method will determine viability of spores by detecting early protein synthesis after chemical germination. During this year, we established the feasibility of this approach and gathered preliminary results that should fuel a future more comprehensive effort. Such a proposal is currently under review with the NIH. Proteomic signatures of Bacillus spores and vegetative cells were assessed by both slab gel electrophoresis as well as microchip based gel electrophoresis employing sensitive laser-induced fluorescence detection. The conditions for germination using a number of chemical germinants were evaluated and optimized and the time course of protein synthesis was ascertained. Microseparations were carried out using both viable spores and spores inactivated by two different methods. A select number of the early synthesis proteins were digested into peptides for analysis by mass spectrometry.
Flows with strong curvature present a challenge for turbulence models, specifically eddy viscosity type models which assume isotropy and a linear and instantaneous equilibrium relation between stress and strain. Results obtained from three different codes and two different linear eddy viscosity turbulence models are compared to a DNS simulation in order to gain some perspective on the turbulence modeling capability of SIERRA/Fuego. The Fuego v2f results are superior to the more common two-layer k-e model results obtained with both a commercial and research code in terms of the concave near wall behavior predictions. However, near the convex wall, including the separated region, little improvement is gained using the v2f model and in general the turbulent kinetic energy prediction is fair at best.
Colloid transport through saturated media is an integral component of predicting the fate and transport of groundwater contaminants. Developing sound predictive capabilities and establishing effective methodologies for remediation relies heavily on our ability to understand the pertinent physical and chemical mechanisms. Traditionally, colloid transport through saturated media has been described by classical colloid filtration theory (CFT), which predicts an exponential decrease in colloid concentration with travel distance. Furthermore, colloid stability as determined by Derjaguin-Landau-Veney-Overbeek (DLVO) theory predicts permanent attachment of unstable particles in a primary energy minimum. However, recent studies show significant deviations from these traditional theories. Deposition in the secondary energy minimum has been suggested as a mechanism by which observed deviations can occur. This work investigates the existence of the secondary energy minimum as predicted by DLVO theory using direct force measurements obtained by Atomic Forces Microscopy. Interaction energy as a function of separation distance between a colloid and a quartz surface in electrolyte solutions of varying ionic strength are obtained. Preliminary force measurements show promise and necessary modifications to the current experimental methodology have been identified. Stringent surface cleaning procedures and the use of high-purity water for all injectant solutions is necessary for the most accurate and precise measurements. Comparisons between direct physical measurements by Atomic Forces Microscopy with theoretical calculations and existing experimental findings will allow the evaluation of the existence or absence of a secondary energy minimum.
In support of the DOE Low Wind Speed Turbine (LWST) program two of the three Micon 65/13M wind turbines at the USDA Agricultural Research Service (ARS) center in Bushland, Texas will be used to test two sets of experimental blades, the CX-100 and TX-100. The blade aerodynamic and structural characterization, meteorological inflow and wind turbine structural response will be monitored with an array of 75 instruments: 33 to characterize the blades, 15 to characterize the inflow, and 27 to characterize the time-varying state of the turbine. For both tests, data will be sampled at a rate of 30 Hz using the ATLAS II (Accurate GPS Time-Linked Data Acquisition System) data acquisition system. The system features a time-synchronized continuous data stream and telemetered data from the turbine rotor. This paper documents the instruments and infrastructure that have been developed to monitor these blades, turbines and inflow.
We define a new method for global optimization, the Homotopy Optimization Method (HOM). This method differs from previous homotopy and continuation methods in that its aim is to find a minimizer for each of a set of values of the homotopy parameter, rather than to follow a path of minimizers. We define a second method, called HOPE, by allowing HOM to follow an ensemble of points obtained by perturbation of previous ones. We relate this new method to standard methods such as simulated annealing and show under what circumstances it is superior. We present results of extensive numerical experiments demonstrating performance of HOM and HOPE.
We performed molecular dynamics simulations of beta-amyloid (A{beta}) protein and A{beta} fragment(31-42) in bulk water and near hydrated lipids to study the mechanism of neurotoxicity associated with the aggregation of the protein. We constructed full atomistic models using Cerius2 and ran simulations using LAMMPS. MD simulations with different conformations and positions of the protein fragment were performed. Thermodynamic properties were compared with previous literature and the results were analyzed. Longer simulations and data analyses based on the free energy profiles along the distance between the protein and the interface are ongoing.
Over the past several years, techniques have been developed for clustering very large segments of the technical literature using sources such as Thomson ISI's Science Citation Index. The primary objective of this work has been to develop indicators of potential impact at the paper level to enhance planning and evaluation of research. These indicators can also be aggregated at different levels to enable profiling of departments, institutions, agencies, etc. Results of this work are presented as maps of science and technology with various overlays corresponding to the indicators associated with a particular search or question.
This report investigates the feasibility of applying Adaptive Mesh Refinement (AMR) techniques to a vector finite element formulation for the wave equation in three dimensions. Possible error estimators are considered first. Next, approaches for refining tetrahedral elements are reviewed. AMR capabilities within the Nevada framework are then evaluated. We summarize our conclusions on the feasibility of AMR for time-domain vector finite elements and identify a path forward.
GaN-based microwave power amplifiers have been identified as critical components in Sandia's next generation micro-Synthetic-Aperture-Radar (SAR) operating at X-band and Ku-band (10-18 GHz). To miniaturize SAR, GaN-based amplifiers are necessary to replace bulky traveling wave tubes. Specifically, for micro-SAR development, highly reliable GaN high electron mobility transistors (HEMTs), which have delivered a factor of 10 times improvement in power performance compared to GaAs, need to be developed. Despite the great promise of GaN HEMTs, problems associated with nitride materials growth currently limit gain, linearity, power-added-efficiency, reproducibility, and reliability. These material quality issues are primarily due to heteroepitaxial growth of GaN on lattice mismatched substrates. Because SiC provides the best lattice match and thermal conductivity, SiC is currently the substrate of choice for GaN-based microwave amplifiers. Obviously for GaN-based HEMTs to fully realize their tremendous promise, several challenges related to GaN heteroepitaxy on SiC must be solved. For this LDRD, we conducted a concerted effort to resolve materials issues through in-depth research on GaN/AlGaN growth on SiC. Repeatable growth processes were developed which enabled basic studies of these device layers as well as full fabrication of microwave amplifiers. Detailed studies of the GaN and AlGaN growth of SiC were conducted and techniques to measure the structural and electrical properties of the layers were developed. Problems that limit device performance were investigated, including electron traps, dislocations, the quality of semi-insulating GaN, the GaN/AlGaN interface roughness, and surface pinning of the AlGaN gate. Surface charge was reduced by developing silicon nitride passivation. Constant feedback between material properties, physical understanding, and device performance enabled rapid progress which eventually led to the successful fabrication of state of the art HEMT transistors and amplifiers.
Thiolated cyclodextrins have been shown to be useful as modifiers of electrode surfaces for application in electrochemical sensing. The adsorption of three different thiolated {beta}-cyclodextrin ({beta}-CD) derivatives onto gold (Au) electrodes was studied by monitoring ferricyanide reduction and ferrocene carboxylic acid (FCA) oxidation at the electrode surface using cyclic voltammetry. Electrodes modified with the {beta}-CD MJF-69 derivative bound FCA within the CD cavity. The monolayer acted as a conducting layer with an increase in the oxidation current. On the other hand, the {beta}-CD layer inhibited the reduction of ferricyanide at the electrode surface since ferricyanide is larger than the cavity of the {beta}-CD derivative and thus unable to form an inclusion complex.
Due to the grave public health implications and economic impact possible with the emergence of the highly pathogenic avian influenza A isolate, H5N1, currently circulating in Asia we have evaluated the efficacy of various disinfectant chemistries against surrogate influenza A strains. Chemistries included in the tests were household bleach, ethanol, Virkon S{reg_sign}, and a modified version of the Sandia National Laboratories developed DF-200 (DF-200d, a diluted version of the standard DF-200 formulation). Validation efforts followed EPA guidelines for evaluating chemical disinfectants against viruses. The efficacy of the various chemistries was determined by infectivity, quantitative RNA, and qualitative protein assays. Additionally, organic challenges using combined poultry feces and litter material were included in the experiments to simulate environments in which decontamination and remediation will likely occur. In all assays, 10% bleach and Sandia DF-200d were the most efficacious treatments against two influenza A isolates (mammalian and avian) as they provided the most rapid and complete inactivation of influenza A viruses.
We present the initial stages of development of new agent-based computational methods to generate and test hypotheses about linkages between environmental change and international instability. This report summarizes the first year's effort of an originally proposed three-year Laboratory Directed Research and Development (LDRD) project. The preliminary work focused on a set of simple agent-based models and benefited from lessons learned in previous related projects and case studies of human response to climate change and environmental scarcity. Our approach was to define a qualitative model using extremely simple cellular agent models akin to Lovelock's Daisyworld and Schelling's segregation model. Such models do not require significant computing resources, and users can modify behavior rules to gain insights. One of the difficulties in agent-based modeling is finding the right balance between model simplicity and real-world representation. Our approach was to keep agent behaviors as simple as possible during the development stage (described herein) and to ground them with a realistic geospatial Earth system model in subsequent years. This work is directed toward incorporating projected climate data--including various C02 scenarios from the Intergovernmental Panel on Climate Change (IPCC) Third Assessment Report--and ultimately toward coupling a useful agent-based model to a general circulation model.3
When developing new hardware for a computer system, bus monitors are invaluable for testing compliance and troubleshooting problems. Bus monitors can be purchased for other common system busses such as the Peripheral Component Interconnect (PCI) bus and the Universal Serial Bus (USB). However, the project team did not find any commercial bus analyzers for the Low Pin Count (LPC) bus. This report will provide a short overview of the LPC interface. Page 3 of 11 This page intentionally left blank.Page 4 of 11
Basic research is needed to better understand the potential risk of dangerous biological agents that are unintentionally or intentionally introduced into a water distribution system. We report on our capabilities to conduct such studies and our preliminary investigations. In 2004, the Biofilms Laboratory was initiated for the purpose of conducting applied research related to biofilms with a focus on application, application testing and system-scale research. Capabilities within the laboratory are the ability to grow biofilms formed from known bacteria or biofilms from drinking water. Biofilms can be grown quickly in drip-flow reactors or under conditions more analogous to drinking-water distribution systems in annular reactors. Biofilms can be assessed through standard microbiological techniques (i .e, aerobic plate counts) or with various visualization techniques including epifluorescent and confocal laser scanning microscopy and confocal fluorescence hyperspectral imaging with multivariate analysis. We have demonstrated the ability to grow reproducible Pseudomonas fluorescens biofilms in the annular reactor with plate counts on the order of 10{sup 5} and 10{sup 6} CFU/cm{sup 2}. Stationary phase growth is typically reached 5 to 10 days after inoculation. We have also conducted a series of pathogen-introduction experiments, where we have observed that both polystyrene microspheres and Bacillus cereus (as a surrogate for B. anthracis) stay incorporated in the biofilms for the duration of our experiments, which lasted as long as 36 days. These results indicated that biofilms may act as a safe harbor for bio-pathogens in drinking water systems, making it difficult to decontaminate the systems.
The ''Advanced Proton-Exchange Materials for Energy Efficient Fuel Cells'' Laboratory Directed Research and Development (LDRD) project began in October 2002 and ended in September 2005. This LDRD was funded by the Energy Efficiency and Renewable Energy strategic business unit. The purpose of this LDRD was to initiate the fundamental research necessary for the development of a novel proton-exchange membranes (PEM) to overcome the material and performance limitations of the ''state of the art'' Nafion that is used in both hydrogen and methanol fuel cells. An atomistic modeling effort was added to this LDRD in order to establish a frame work between predicted morphology and observed PEM morphology in order to relate it to fuel cell performance. Significant progress was made in the area of PEM material design, development, and demonstration during this LDRD. A fundamental understanding involving the role of the structure of the PEM material as a function of sulfonic acid content, polymer topology, chemical composition, molecular weight, and electrode electrolyte ink development was demonstrated during this LDRD. PEM materials based upon random and block polyimides, polybenzimidazoles, and polyphenylenes were created and evaluated for improvements in proton conductivity, reduced swelling, reduced O{sub 2} and H{sub 2} permeability, and increased thermal stability. Results from this work reveal that the family of polyphenylenes potentially solves several technical challenges associated with obtaining a high temperature PEM membrane. Fuel cell relevant properties such as high proton conductivity (>120 mS/cm), good thermal stability, and mechanical robustness were demonstrated during this LDRD. This report summarizes the technical accomplishments and results of this LDRD.
Cation binding by polysaccharides is observed in many environments and is important for predictive environmental modeling, and numerous industrial and food technology applications. The complexities of these organo-cation interactions are well suited to predictive molecular modeling studies for investigating the roles of conformation and configuration of polysaccharides on cation binding. In this study, alginic acid was chosen as a model polymer and representative disaccharide and polysaccharide subunits were modeled. The ability of disaccharide subunits to bind calcium and to associate with the surface of calcite was investigated. The findings were extended to modeling polymer interactions with calcium ions.
Our aim is to determine the network of events, or the regulatory network, that defines an immune response to a bio-toxin. As a model system, we are studying T cell regulatory network triggered through tyrosine kinase receptor activation using a combination of pathway stimulation and time-series microarray experiments. Our approach is composed of five steps (1) microarray experiments and data error analysis, (2) data clustering, (3) data smoothing and discretization, (4) network reverse engineering, and (5) network dynamics analysis and fingerprint identification. The technological outcome of this study is a suite of experimental protocols and computational tools that reverse engineer regulatory networks provided gene expression data. The practical biological outcome of this work is an immune response fingerprint in terms of gene expression levels. Inferring regulatory networks from microarray data is a new field of investigation that is no more than five years old. To the best of our knowledge, this work is the first attempt that integrates experiments, error analyses, data clustering, inference, and network analysis to solve a practical problem. Our systematic approach of counting, enumeration, and sampling networks matching experimental data is new to the field of network reverse engineering. The resulting mathematical analyses and computational tools lead to new results on their own and should be useful to others who analyze and infer networks.
Field-structured magnetic particle composites are an important new class of materials that have great potential as both sensors and actuators. These materials are synthesized by suspending magnetic particles in a polymeric resin and subjecting these to magnetic fields while the resin polymerizes. If a simple uniaxial magnetic field is used, the particles will form chains, yielding composites whose magnetic susceptibility is enhanced along a single direction. A biaxial magnetic field, comprised of two orthogonal ac fields, forms particle sheets, yielding composites whose magnetic susceptibility is enhanced along two principal directions. A balanced triaxial magnetic field can be used to enhance the susceptibility in all directions, and biased heterodyned triaxial magnetic fields are especially effective for producing composites with a greatly enhanced susceptibility along a single axis. Magnetostriction is quadratic in the susceptibility, so increasing the composite susceptibility is important to developing actuators that function well at modest fields. To investigate magnetostriction in these field-structured composites we have constructed a sensitive, constant-stress apparatus capable of 1 ppm strain resolution. The sample geometry is designed to minimize demagnetizing field effects. With this apparatus we have demonstrated field-structured composites with nearly 10,000 ppm strain.
Since the 1960's, Sandia National Laboratories (SNL) has conducted radiation effects testing for the Department of Energy (DOE) and other contractors supporting the DOE. Over this time, SNL's Technical Area V (TA-V) has operated research reactor facilities whose primary mission is providing appropriate neutron radiation environments for radiation testing and qualification of electronic components and other devices. The current generation of reactors includes the Annular Core Research Reactor (ACRR), a water-moderated pool-type reactor, fueled by elements constructed from UO 2-BeO ceramic fuel pellets, and the Sandia Pulse Reactor (SPR), a bare metal fast burst reactor utilizing a uranium-molybdenum alloy fuel. The ACRR has a 9-inch inner diameter central cavity, providing a means to expose reasonably large experiments to an epithermal neutron radiation environment. The ACRR also has a 20-inch inner diameter excore cavity surrounded by U-ZrH fuel elements to accommodate larger experiments. The SPR has a 6.5-inch inner diameter cavity, providing a means to expose experiments to neutron radiation environment which approximates a fission spectrum. The SPR is operated in a large reactor room which allows for experiments to be located external to the reactor and irradiated by the neutrons which leak from the reactor. Both the ACRR and the SPR may be operated in a steady-state or pulsed mode. In pulse mode, the ACRR and SPR can attain high-power pulses on the order of 40 GW (10 ms pulse width) and ISO GW (80 μs pulse width), respectively. The ACRR can also be operated in a transient mode, allowing for tailored power profiles ranging from tens to a few hundred MW for durations of a few seconds. The reactors have also been utilized to perform reactor fuel materials testing, reactor accident phenomenology testing, investigation of reactorpumped lasers, and space reactor fuel component testing. Various tests have included effects such as melting and vaporization of materials due to fission heating and have been conducted in environments including molten sodium, hydrogen gas, mechanical shocks greater than 1000 g, and cryogenic temperatures. In addition, TA-V has performed a variety of critical assembly experiments for purposes of gathering reactor physics benchmark data for space reactor fuel, and characterization of fission product reactivity effects for transportation criticality studies. This presentation provides an overview of the various radiation effects testing and critical experiment facilities, their capabilities and radiation environments, and the wide variety of testing for which the facilities have been utilized.
American Nuclear Society Embedded Topical Meeting - 2005 Space Nuclear Conference
Lenard, Roger X.; Youchison, Dennis L.; Williams, Brian E.; Anghaie, Samim
Under an NASA STTR project funded through Marshall Space Flight Center, a team from Ultramet Inc., Sandia National Laboratories and the University of Florida has been developing a new high temperature, tricarbide fuel matrix consisting of ZrC, NbC and UC using an open-cell reticulated foam skeleton. The new fuel is envisioned for use in nuclear thermal propulsion systems, bi-modal reactors and terrestrial high temperature gas reactors and builds on the tricarbide fuel research in the former Soviet Union. This paper deals with conceptual mechanical and neutronics design of a NTR reactor core and pressure vessel by the team. The details of fuel form fabrication and foam layout is the subject of a companion paper. It is highly desirable for a nuclear thermal rocket reactor to provide low ΔTs between the fuel and the hydrogen propellant; this bespeaks a minimal fuel-propellant temperature gap. However, NTRs, in order to exhibit a significant power density, possess high thermal gradients. Historically, this has resulted in NTR core designs that were neutronically acceptable but either heavy (due to prismatic element design) or insufficiently mechanically robust. The new fuel is both mechanically robust and thermally efficient given its extremely high surface area, higher melting point, minimal thermal stresses, and much reduced pressure drop compared to conventional fuel types. The matrix is anticipated to operate at temperatures as high as 3000K with minimal hydrogen erosion. The foam is an engineered material in which the porosity, size and thermal conductivity of the ligaments can be controlled independently to meet specific requirements. In this article we review the design process of the foam fuel based NTR, a procedure that has resulted in a quite compact, epi-thermal spectrum reactor core that can produce high power densities A credible reactor design is described herein that will allow us to couple these results with a new MP-CFD modeling capability using detailed simulation of the porous media. Our near-term plans for infiltration of the matrix with UC, integration of the test article and hydrogen testing at the University of Florida and Marshall Space Flight Center Future possibilities for continued development and testing are summarized.
This paper documents research into the use of an adaptive cultural model and collective intelligence as a means of characterizing the reliability of bulk power networks. Historically, utilities support the reliable design and operation of bulk power networks through first-order contingency analysis. In contingency analyses the list of candidate elements for disruption are identified by engineers a priori based on the rate at which the elements failure through the course of normal grid operation. The new method, an implementation of particle swarm analysis, a swarm of 'virtual power engineers' successfully identified the set of network elements which, if disrupted, would possibly lead to a cascading series of events resulting in the most wide spread damage. The methodology is technology independent: it can be applied on not only for reliability analysis of bulk power systems, but also other energy systems or transportation systems. The methodology is scale neutral: it can be applied to power distribution networks at the local, state or regional level.