Submittal of Updated Reference Documents Cited in the Chemical Waste Landfill Post-Closure Care Permit for Sandia National Laboratories/New Mexico (SNL/NM) Environmental Protection Agency Identification Number NM5890110518
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PIER B
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Applied Physics Letters
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In experiments conducted on the RITS-6 accelerator, the SMP diode exhibits sig- ni cant shot-to-shot variability. Speci cally, for identical hardware operated at the same voltage, some shots exhibit a catastrophic drop in diode impedance. A study is underway to identify sources of shot-to-shot variations which correlate with diode impedance collapse. To remove knob emission as a source, only data from a shot series conducted with a 4.5-MV peak voltage are considered. The scope of this report is limited to sources of variability which occur away from the diode, such as power ow emission and trajectory changes, variations in pulsed power, dustbin and transmission line alignment, and di erent knob shapes. We nd no changes in the transmission line hardware, alignment, or hardware preparation methods which correlate with impedance collapse. However, in classifying good versus poor shots, we nd that there is not a continuous spectrum of diode impedance behavior but that the good and poor shots can be grouped into two distinct impedance pro les. This result forms the basis of a follow-on study focusing on the variability resulting from diode physics. 3
Distributed energy resources (DER) such as photovoltaic (PV) systems, when deployed in a large scale, are capable of influencing significantly the operation of power systems. Looking to the future, stakeholders are working on standards to make it possible to manage the potentially complex interactions between DER and the power system. In 2009, the Electric Power Research Institute (EPRI), Sandia National Laboratories (SNL) with the U.S. Department of Energy (DOE), and the Solar Electric Power Association (SEPA) initiated a large industry collaborative to identify and standardize definitions for a set of DER grid support functions. While the initial effort concentrated on grid-tied PV inverters and energy storage systems, the concepts have applicability to all DER. A partial product of this on-going effort is a reference definitions document (IEC TR 61850-90-7, Object models for power converters in distributed energy resources (DER) systems) that has become a basis for expansion of related International Electrotechnical Commission (IEC) standards, and is supported by US National Institute of Standards and Technology (NIST) Smart Grid Interoperability Panel (SGIP). Some industry-led organizations advancing communications protocols have also embraced this work. As standards continue to evolve, it is necessary to develop test protocols to independently verify that the inverters are properly executing the advanced functions. Interoperability is assured by establishing common definitions for the functions and a method to test compliance with operational requirements. This document describes test protocols developed by SNL to evaluate the electrical performance and operational capabilities of PV inverters and energy storage, as described in IEC TR 61850-90-7. While many of these functions are not now required by existing grid codes or may not be widely available commercially, the industry is rapidly moving in that direction. Interoperability issues are already apparent as some of these inverter capabilities are being incorporated in large demonstration and commercial projects. The test protocols are intended to be used to verify acceptable performance of inverters within the standard framework described in IEC TR 61850-90-7. These test protocols, as they are refined and validated over time, can become precursors for future certification test procedures for DER advanced grid support functions.
Sandia National Laboratories has created a test protocol for IEC TR 61850-90-7 advanced distributed energy resource (DER) functions, titled "Test Protocols for Advanced Inverter Interoperability Functions," often referred to as the Sandia Test Protocols. This document is currently in draft form, but has been shared with stakeholders around the world with the ultimate goal of collaborating to create a consensus set of test protocols which can be then incorporated into an International Electrotechnical Commission (IEC) and/or Underwriters Laboratories (UL) certification standard. The protocols are designed to ensure functional interoperability of DER (primarily photovoltaic (PV) inverters and energy storage systems) as specified by the IEC technical report through communication and electrical tests. In this report, Sandia exercises the electrical characterization portion of the test protocols for four functions: constant power factor (INV3), volt-var (VV11), frequency-watt (FW21), and Low and High Voltage Ride Through (L/HVRT). The goal of the tests reported here was not to characterize the performance of the equipment under test (EUT), but rather to (a) exercise the draft Sandia Test Protocols in order to identify any revisions needed in test procedures, conditions, or equipment and (b) gain experience with state-of-the-art DER equipment to determine if the tests put unrealistic or overly aggressive requirements on EUT operation. In performing the work according to the current versions of the protocols, Sandia was able to identify weaknesses in the current versions and suggest improvements to the test protocols.
Distributed energy resources (DER) such as photovoltaic (PV) systems, when deployed in a large scale, are capable of influencing significantly the operation of power systems. Looking to the future, stakeholders are working on standards to make it possible to manage the potentially complex interactions between DER and the power system. In 2009, the Electric Power Research Institute (EPRI), Sandia National Laboratories (SNL) with the U.S. Department of Energy (DOE), and the Solar Electric Power Association (SEPA) initiated a large industry collaborative to identify and standardize definitions for a set of DER grid support functions. While the initial effort concentrated on grid-tied PV inverters and energy storage systems, the concepts have applicability to all DER. A partial product of this on-going effort is a reference definitions document (IEC TR 61850-90-7, Object models for power converters in distributed energy resources (DER) systems) that has become a basis for expansion of related International Electrotechnical Commission (IEC) standards, and is supported by US National Institute of Standards and Technology (NIST) Smart Grid Interoperability Panel (SGIP). Some industry-led organizations advancing communications protocols have also embraced this work. As standards continue to evolve, it is necessary to develop test protocols to independently verify that the inverters are properly executing the advanced functions. Interoperability is assured by establishing common definitions for the functions and a method to test compliance with operational requirements. This document describes test protocols developed by SNL to evaluate the electrical performance and operational capabilities of PV inverters and energy storage, as described in IEC TR 61850-90-7. While many of these functions are not currently required by existing grid codes or may not be widely available commercially, the industry is rapidly moving in that direction. Interoperability issues are already apparent as some of these inverter capabilities are being incorporated in large demonstration and commercial projects. The test protocols are intended to be used to verify acceptable performance of inverters within the standard framework described in IEC TR 61850-90-7. These test protocols, as they are refined and validated over time, can become precursors for future certification test procedures for DER advanced grid support functions.
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IEEE Control Sytems Technology
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The performance of an Inverse Synthetic Aperture Radar (ISAR) system depends on a variety of factors, many which are interdependent in some manner. In this report we specifically examine ISAR as applied to maritime targets (e.g. ships). It is often difficult to get your arms around the problem of ascertaining achievable performance limits, and yet those limits exist and are dictated by physics. This report identifies and explores those limits, and how they depend on hardware system parameters and environmental conditions. Ultimately, this leads to a characterization of parameters that offer optimum performance for the overall ISAR system. While the information herein is not new to the literature, its collection into a single report hopes to offer some value in reducing the seek time.
SIAM Review
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Data, a brief description of key boundary conditions, and results of Sandia National Laboratories’ ongoing MELCOR analysis of the Fukushima Unit 2 accident are given for the reactor core isolation cooling (RCIC) system. Important assumptions and related boundary conditions in the current analysis additional to or different than what was assumed/imposed in the work of SAND2012-6173 are identified. This work is for the U.S. Department of Energy’s Nuclear Energy University Programs fiscal year 2014 Reactor Safety Technologies Research and Development Program RC-7: RCIC Performance under Severe Accident Conditions.
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Optics Express
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The purpose of this effort is to explore where the availability of water could be a limiting factor in the siting of new electric power generation. To support this analysis, water availability is mapped at the county level for the conterminous United States (3109 counties). Five water sources are individually considered, including unappropriated surface water, unappropriated groundwater, appropriated water (western U.S. only), municipal wastewater and brackish groundwater. Also mapped is projected growth in non-thermoelectric consumptive water demand to 2035. Finally, the water availability metrics are accompanied by estimated costs associated with utilizing that particular supply of water. Ultimately these data sets are being developed for use in the National Renewable Energy Laboratories' (NREL) Regional Energy Deployment System (ReEDS) model, designed to investigate the likely deployment of new energy installations in the U.S., subject to a number of constraints, particularly water.
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We have developed a MEMS based thin (<100 μm), temperature stable (< 1 parts-per-billion per degree Celsius (ppb/°C)), low power (<10 mW), frequency reference. Traditional high stability oscillators are based on quartz crystals. While a mature technology, the large size of quartz crystals presents important mission barriers including reducing oscillator thickness below 400 μm, and low power temperature stabilization (ovenizing). The small volume microresonators are 2 μm thick compared to 100’s of microns for quartz, and provide acoustic/thermal isolation when suspended above the substrate by narrow beams. This isolation enables a new paradigm for ovenizing oscillators at revolutionary low power levels <10 mW as compared to >300 mW for oven controlled quartz oscillators (OCXO). The oven controlled MEMS oscillator (OCMO) takes advantage of high thermal isolation and CMOS integration to ovenize the entire oscillator (AlN resonator and CMOS) on a suspended platform. This enables orders of magnitude reductions in size and power as compared with today's OCXO technology.
14th International High-Level Radioactive Waste Management Conference, IHLRWMC 2013: Integrating Storage, Transportation, and Disposal
Dose rate calculations for a receptor well in a generic reference aquifer are highly dependent on the mixing that occurs in the aquifer and well. This paper presents analytical expressions for determining radionuclide concentrations at the receptor well in a generic aquifer by calculating the overall dilution that occurs in the system and factoring in the effects of travel time and radionuclide decay. Expressions are derived for four types of sources: vertical borehole (advective), point source (advective), point source (diffusive), and broad area diffusion. Example applications of each solution are presented and compared.
14th International High-Level Radioactive Waste Management Conference, IHLRWMC 2013: Integrating Storage, Transportation, and Disposal
Research on deep borehole disposal of high-level radioactive waste has indicated that the deep borehole disposal concept is a viable potential alternative to a mined repository system. Previous modeling indicates that thermally induced fluid flow associated with heat from the waste has the greatest potential for the upward transport of dissolved radionuclides. An updated thermal-hydrologic model of a deep borehole disposal system is constructed using a recently developed reference design, incorporating a more realistic heterogeneous representation of the hydrogeological system with depth-varying permeability and thermal conductivity, coupled stratification of salinity and fluid density, and arrays of up to 81 disposal boreholes. Results show that peak temperatures near the borehole occur within 20 years of disposal, with an extended period of elevated temperatures beyond 10, 000 years and a second, lower peak in temperature near the center of larger borehole arrays. Simulated vertical upward groundwater flux in the borehole and disturbed rock zone occurs in the waste disposal zone and overlying seal zone at greatest magnitude for about 100 years, but persists for an extended period of time. The persistence of simulated vertical groundwater flow beyond 1, 000 years increases with the number of disposal boreholes in the array. This persistence in flow may have important implications for the maximum number of disposal boreholes that could be safely emplaced at a single site.
14th International High-Level Radioactive Waste Management Conference, IHLRWMC 2013: Integrating Storage, Transportation, and Disposal
Within the Used Fuel Disposition Campaign (UFDC) of the United States Department of Energy Office of Nuclear Energy (DOE-NE), we have investigated used fuel (UF) degradation and radionuclide mobilization (UFD&RM) and implemented/produced a set of models encompassing radiolytic processes, UF matrix degradation, instant release fractions (IRF) of key radionuclides, and first-principles atomistic models for UO2 and its potential corrosion products. The goals of this collaborative effort (among three different national laboratories: Argonne National Laboratory [ANL]; Pacific Northwest National Laboratory [PNNLJ; and Sandia National Laboratories [SNL]) are to enhance the understanding of UF degradation processes and the technical bases for safety analyses in a range of generic disposal environments. In addition to these modeling efforts, integrated experimental studies are being conducted at both ANL and PNNL to evaluate and validate (and ultimately expand) process models for radiolytic phenomena and UF matrix degradation in various geologic disposal conditions. Integration and coupling of these process models into a generic performance assessment model (GPAM) is one focus of SNL efforts within the generic analyses of the Engineered Barrier System (EBS) for various repository environments. As discussed below, the present work has produced a set of models for implementation into the GPAM as an initial step towards an enhanced coupled model of source-term processes.
14th International High-Level Radioactive Waste Management Conference, IHLRWMC 2013: Integrating Storage, Transportation, and Disposal
Once sufficiently cool, spent nuclear fuel is stored in dry storage cask systems, most commonly consisting of welded stainless steel containers enclosed in ventilated concrete or steel overpacks. As the United States does not currently have a viable disposal pathway for SNF, these containers may be required to perform their waste isolation function for many decades beyond their original design criteria. Failure by stress corrosion cracking due to deliquescence of deposited salt aerosols is a major concern. Parameters controlling deliquescence include the temperature and RH at the waste package surface, and the composition of deposited salts. The timing and duration of deliquescence under in situ conditions is poorly defined, because of uncertainties in thermal history, the large variability in temperatures over the storage container surface, and uncertainties in the composition of deposited salts. Storage installations in near-marine environments are of greatest concern because of exposure to significant quantities of chloride-rich sea salt aerosols. Published stainless steel corrosion studies with sea salt and sea salt components suggest that conditions conducive to localized corrosion initiation and propagation may exist on the surface of SNF storage containers in such environments at some point in their extended service life, and furthermore, that stress corrosion cracking may occur over a broad range of potentially relevant conditions. However, the studies were carried out with heavy salt loads and limited gas flow, which may limit the beneficial effects of brine/atmosphere exchange (e.g., acid degassing, CO2 exchange, degassing and thermal decomposition of ammonium phases). Gas exchange with the atmosphere will modify brine pH and chloride content, and will modify the deliquescent salt assemblage through precipitation of Ca and Mg carbonates, potentially limiting brine volumes or resulting in dryout. Nitrate-rich inland salt aerosols are considered less corrosive, but may have higher levels of potentially reactive pollutants. Moreover, the compositions of inland salt deposits on hot storage containers may have greater uncertainty, as ammonium- and nitrate-rich salt assemblages are subject to thermal decomposition and potential reactions with organics. For both inland and near-marine sites, little information is available on the dust/salt deposition rates, or the quantity of salt present on existing storage container surfaces. A sampling program for in situ dust deposits on current storage containers will provide critical compositional data for new stress corrosion cracking studies, and will allow evaluation of the applicability of existing studies of stainless steel stress corrosion cracking under conditions of dust deliquescence.
14th International High-Level Radioactive Waste Management Conference, IHLRWMC 2013: Integrating Storage, Transportation, and Disposal
A hybrid Potts-phase field model to simulate hydride nucleation and growth in Zr-claddings is presented. It simulates nucleation of hydrides at grain boundaries and their subsequent growth by diffusion of hydrogen to precipitates. The model is demonstrated by simulating hydride precipitation in two different cladding of identical composition, but different grain structures. The claddings are supersaturated with hydrogen as would be expected after drying at the beginning of dry storage. The resulting hydrides have distinct morphologies with implications for the mechanical behavior and fracture strength of the claddings after dry storage.
14th International High-Level Radioactive Waste Management Conference, IHLRWMC 2013: Integrating Storage, Transportation, and Disposal
This paper reports the results of a series of multiyear experiments investigating the anoxic corrosion of steel and Pb alloys in NaCl±Mg brines under WIPP-relevant conditions. The objectives of this work are to determine: (a) the extent to which steel and Pb consume CO2 via the formation of carbonates or other phases, potentially supporting MgO in CO 2 sequestration; and (b) corrosion rates that can then be used to calculate hydrogen gas generation rates for use in WIPP performance assessment calculations.
14th International High-Level Radioactive Waste Management Conference, IHLRWMC 2013: Integrating Storage, Transportation, and Disposal
Significant laboratory and in situ testing has been conducted by both the United States and Germany on salt disposal of heat-generating radioactive waste. Coupled simulation capabilities recently developed in other fields are now being applied to repository design and performance confirmation. New efforts are underway to benchmark this latest generation of numerical models, requiring quality validation datasets. Datasets associated with historic high-level waste (HL W) field experiments at the Waste Isolation Pilot Plant in New Mexico, Avery Island in Louisiana, Asse II in Germany, and Project Salt Vault in Kansas should be considered before constructing new experiments. We constructed an online bibliographic database using the web reference database (Refbase) distribution to contain references to reports, and conference papers, along with associated electronic copies of reports and associated data. The database was populated using publically available Department of Energy sources and project-specific archives scanned for this project. The browser-based database facilitated an extensive collaborative review of experiments in geologic salt-primarily concerning heated salt that may be applicable to modern code validation efforts. We summarize historic in situ tests conducted in geologic salt, focusing on heated salt creep, heated brine migration, and crushed salt reconsolidation. We propose several candidate thermal, mechanical, and hydrological validation datasets for salt behavior under repository conditions.
14th International High-Level Radioactive Waste Management Conference, IHLRWMC 2013: Integrating Storage, Transportation, and Disposal
The use of integrated probabilistic risk assessment tools to evaluate the barrier capability of a natural barrier system (NBS) in a nuclear waste repository is presented. The integrated risk assessment tools encompass highly detailed process models for flow and transport, probabilistic performance assessment (PA), and database management. In this paper development of an integrated tool for the modeling of far-field radionuclide transport in a generic salt repository is discussed. The tool was developed by wrapping the flow and transport reservoir simulator (FEHM) with the uncertainty quantification and optimization code (DAKOTA).
14th International High-Level Radioactive Waste Management Conference, IHLRWMC 2013: Integrating Storage, Transportation, and Disposal
For the interim storage of used nuclear fuel, the storage casks/containers will be exposed to conditions under which considerable dust and/or atmospheric aerosols may be deposited on the surface. These dust layers may contain a sizeable portion of water soluble salts, particularly in marine environments where many interim storage systems are located. These soluble salts will deliquesce if sufficient moisture is present, resulting in the formation of potentially corrosive brine on the material surface. Experimental results have illustrated that some stainless steels, such as 304SS (a common material of construction for interim storage containers) can and will undergo localized corrosion in elevated temperature conditions where a chloride rich brine has formed on the surface. Results presented here illustrate that it is possible that stifling of localized attack will result when limited reactant is present, but additional analysis is necessary before a definite conclusion can be made.
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Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics)
For positive integers n, d, consider the hypergrid [n]d with the coordinate-wise product partial ordering denoted by ≺. A function f: [n]d → ℕ is monotone if ∀x ≺ y, f(x) ≤ f(y). A function f is ε-far from monotone if at least an ε-fraction of values must be changed to make f monotone. Given a parameter ε, a monotonicity tester must distinguish with high probability a monotone function from one that is ε-far. We prove that any (adaptive, two-sided) monotonicity tester for functions f : [n]d → ℕ must make Ω(ε -1 d log n - ε-1 log ε-1) queries. Recent upper bounds show the existence of O(ε-1 d log n) query monotonicity testers for hypergrids. This closes the question of monotonicity testing for hypergrids over arbitrary ranges. The previous best lower bound for general hypergrids was a non-adaptive bound of Ω(d log n). © 2013 Springer-Verlag.
The attached cost analyses sheets have been developed for use in planning during the Third Party Alternative study currently underway for the Sandia CREATE project. This cost analysis builds upon the previously submitted base estimate dated June 14, 2013 and includes comparison information collected during a Market Validation exercise conducted in August/September 2013.
Journal of Chemical Physics
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Soft Matter
We demonstrate the ability to change the thermal conductivity of a magnetic platelet suspension from insulating to conducting by using either uniaxial or multiaxial ac magnetic fields to control the suspension structure and dynamics. The equivalent thermal conductivity of the suspension can be modified either by creating static particle structures that facilitate or block heat transfer, or by using multiaxial ac fields to drive emergent particle dynamics that create vigorous, organized, non-contact flow. The equivalent thermal conductivity of a single suspension can be varied over a 100-fold range, and an equivalent thermal conductivity as high as 18.3 W m-1 K-1 has been achieved in an aqueous suspension containing only 2.0 vol% platelets. This value is more than twice the conductivity of liquid mercury. © 2013 The Royal Society of Chemistry.
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Journal of Physics. Condensed Matter
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IEEE Computer Society Conference on Computer Vision and Pattern Recognition Workshops
Multiple-look fusion is quickly becoming more important in statistical pattern recognition. With increased computing power and memory one can make many measurements on an object of interest using, for example, video imagery or radar. By obtaining more views of an object, a system can make decisions with lower missed detection and false alarm errors. There are many approaches for combining information from multiple looks and we mathematically compare and contrast the sequential probability ratio test, Bayesian fusion, and Dempster-Shafer theory of evidence. Using a consistent probabilistic framework we demonstrate the differences and similarities between the approaches and show results for an application in infrared video classification. © 2013 IEEE.
Journal of the ACM
We study the problem of identity testing for depth-3 circuits of top fanin k and degree d. We give a newstructure theorem for such identities that improves the known deterministic dkO(k) -time blackbox identitytest over rationals [Kayal and Saraf, 2009] to one that takes dO(k2)-time. Our structure theorem essentiallysays that the number of independentvariables in a real depth-3 identity is very small. This theoremaffirmatively settles the strong rankconjecture posed by Dvir and Shpilka [2006].We devise various algebraic tools to study depth-3 identities, and use these tools to show that any depth-3identity contains a much smaller nucleus identity that contains most of the "complexity" of the main identity.The special properties of this nucleus allow us to get near optimal rank bounds for depth-3 identities. Themost important aspect of this work is relating a field-dependent quantity, the Sylvester-Gallai rank bound,to the rankof depth-3 identities. We also prove a high-dimensional Sylvester-Gallai theorem for all fields,and get a general depth-3 identity rank bound (slightly improving previous © 2013 ACM.
Metallurgical and Materials Transactions A: Physical Metallurgy and Materials Science
The deformation, crack nucleation, coalescence, and rupture process of pure tantalum (99.9 pct) were studied under room temperature quasistatic loading using several in situ and ex-situ techniques including optical metallography, scanning electron microscopy (SEM), electron backscatter diffraction (EBSD), and transmission-electron microscopy (TEM). The fracture surface of tantalum forms a ridge-and-valley morphology that is distinct from conventional notions of ductile dimple microvoid coalescence, and also distinct from spall damage formed during dynamic shock conditions. Failure proceeds by void nucleation at a dislocation cell wall or in subgrain interiors. Coalescence appears to involve a two-stage damage progression: first individual voids coalesce along the tensile axis forming diamond-shaped multivoid cavities; then cavities link-up by intercavity necking. Final rupture occurs when the intercavity necks thin to ~100-nm films and fail by crystallographic cleavage. This final tearing process was observed using in situ TEM tensile deformation of a thin tantalum film. The detailed microstructural and morphological observations of the current study can be used to guide the development of improved models for tearing of ductile metals. © 2013 The Author(s).
Acta Geotechnica
This paper presents a multiscale analysis of a dilatant shear band using a three-dimensional discrete element method and a lattice Boltzmann/finite element hybrid scheme. In particular, three-dimensional simple shear tests are conducted via the discrete element method. A spatial homogenization is performed to recover the macroscopic stress from the micro-mechanical force chains. The pore geometries of the shear band and host matrix are quantitatively evaluated through morphology analyses and lattice Boltzmann/finite element flow simulations. Results from the discrete element simulations imply that grain sliding and rotation occur predominately with the shear band. These granular motions lead to dilation of pore space inside the shear band and increases in local permeability. While considerable anisotropy in the contact fabric is observed with the shear band, anisotropy of the permeability is, at most, modest in the assemblies composed of spherical grains. © 2013 Springer-Verlag Berlin Heidelberg (outside the USA).
Journal of Applied Phycology
Photosynthetically derived fuels, such as those produced by microalgae, are touted as a future renewable energy source and a means for achieving energy independence. Realization of these claims, however, will require fuel production rates beyond the native capabilities of these microorganisms. The development of a metabolic engineering toolkit for microalgae will be key for reaching the production rates necessary for fuel production. This work advances the toolkit for cyanobacterial fuels by exploring the use of eukaryotic algal gene sources for free fatty acid biosynthesis rather than the traditional bacterial and plant sources. Many species of eukaryotic algae naturally accumulate high levels of triacylglycerol, a compound requiring three fatty acid side chains. Triacylglycerol accumulation implies that eukaryotic algae have naturally efficient enzymes for free fatty acid production, representing an unexplored resource for metabolic engineering targets. In this work, the model cyanobacterium, Synechococcus elongatus PCC7942, was engineered for free fatty acid production by targeting three main rate-limiting steps: (1) fatty acid release, catalyzed by a thioesterase, (2) fixation of carbon by ribulose-1,5-bisphosphate carboxylase/oxygenase, and (3) the first committed step in fatty acid biosynthesis, acetyl-CoA carboxylase. The recombinant acyl-ACP thioesterase and acetyl-CoA carboxylase were derived from the model green alga, Chlamydomonas reinhardtii CC-503. By targeting these proposed rate-determining steps, free fatty acid production was improved on a cell weight basis; however, the overall concentration of excreted free fatty acid did not increase. Recombinant gene expression was optimized by using native promoters, and while expression improved, the free fatty acid yield did not likewise increase. From physiological measurements, it was determined that free fatty acid production in S. elongatus PCC7942 is ultimately limited by the negative physiological effects associated with free fatty acid synthesis rather than bottlenecks within the metabolic pathway. This work demonstrates the successful expression of algal genes in a cyanobacterial host, but further improvement in free fatty acid yields will only be possible when the negative effects of free fatty acid production are mitigated. © 2013 Springer Science+Business Media Dordrecht (outside the USA).
Proceedings of the Institution of Civil Engineers: Engineering Sustainability
Complex adaptive systems are central to many persistent problems locally and globally. In cases where the effects of a policy play out slowly and propagate through interdependencies with other systems, the broader view and understanding gained from complex adaptive system analyses allow us to recognise the causal relationships involved and solve persistent system-level issues. This is particularly true with the risks due to climate change, economic crises, energy disruptions and food insecurity. Climate change and the challenge of addressing the resulting global risks provides a common set of problems on which to build a global community of practice that utilises earth systems' engineering approaches and sustainability goals to understand and resolve problems in complex adaptive systems of systems. Structural adaptation under environmental stress, simple rules for entity interactions and conditiondependent behaviours are key attributes of complex systems. These attributes provide the means for creating models that behave the way the real system does and for the same reasons, improving understanding and designing effective solutions. This paper presents general concepts for infrastructure adaptation and examples of successful applications of an expanded engineering process for complex systems of systems.
This work is being performed for Matt Channon Consulting as part of the Sandia National Laboratories New Mexico Small Business Assistance Program (NMSBA). Matt Channon Consulting has requested Sandia's assistance in the design of a chemical Bunsen reactor for the reaction of SO2, I2 and H2O to produce H2SO4 and HI with a SO2 feed rate to the reactor of 50 kg/hour. Based on this value, an assumed reactor efficiency of 33%, and kinetic data from the literature, a plug flow reactor approximately 1%E2%80%9D diameter and and 12 inches long would be needed to meet the specification of the project. Because the Bunsen reaction is exothermic, heat in the amount of approximately 128,000 kJ/hr would need to be removed using a cooling jacket placed around the tubular reactor. The available literature information on Bunsen reactor design and operation, certain support equipment needed for process operation and a design that meet the specification of Matt Channon Consulting are presented.
Journal of Computational Physics
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Topological quantum computation (TQC) has emerged as one of the most promising approaches to quantum computation. Under this approach, the topological properties of a non-Abelian quantum system, which are insensitive to local perturbations, are utilized to process and transport quantum information. The encoded information can be protected and rendered immune from nearly all environmental decoherence processes without additional error-correction. It is believed that the low energy excitations of the so-called =5/2 fractional quantum Hall (FQH) state may obey non-Abelian statistics. Our goal is to explore this novel FQH state and to understand and create a scientific foundation of this quantum matter state for the emerging TQC technology. We present in this report the results from a coherent study that focused on obtaining a knowledge base of the physics that underpins TQC. We first present the results of bulk transport properties, including the nature of disorder on the 5/2 state and spin transitions in the second Landau level. We then describe the development and application of edge tunneling techniques to quantify and understand the quasiparticle physics of the 5/2 state.
Materials Science and Engineering. A, Structural Materials: Properties, Microstructure and Processing
Crystallographic slip planes in body centered cubic (BCC) metals are not fully understood. In polycrystals, there are additional confounding effects from grain interactions. This paper describes an experimental investigation into the effects of grain orientation and neighbors on elastic–plastic strain accumulation. In situ strain fields were obtained by performing digital image correlation (DIC) on images from a scanning electron microscope (SEM) and from optical microscopy. These strain fields were statistically compared to the grain structure measured by electron backscatter diffraction (EBSD). Spearman rank correlations were performed between effective strain and six microstructural factors including four Schmid factors associated with the <111> slip direction, grain size, and Taylor factor. Modest correlations (~10%) were found for a polycrystal tension specimen. The influence of grain neighbors was first investigated by re-correlating the polycrystal data using clusters of similarly-oriented grains identified by low grain boundary misorientation angles. Second, the experiment was repeated on a tantalum oligocrystal, with through-thickness grains. Much larger correlation coefficients were found in this multicrystal due to the dearth of grain neighbors and subsurface microstructure. Finally, a slip trace analysis indicated (in agreement with statistical correlations) that macroscopic slip often occurs on {110}<111> slip systems and sometimes by pencil glide on maximum resolved shear stress planes (MRSSP). These results suggest that Schmid factors are suitable for room temperature, quasistatic, tensile deformation in tantalum as long as grain neighbor effects are accounted for.
Progress toward predictions of the statistics of particle time-temperature histories is presented. These predictions are to be made using Lagrangian particle models within the one-dimensional turbulence (ODT) model. In the present reporting period we have further characterized the performance, behavior and capabilities of the particle dispersion models that were added to the ODT model in the first period. We have also extended the capabilities in two manners. First we provide alternate implementations of the particle transport process within ODT; within this context the original implementation is referred to as the type-I and the new implementations are referred to as the type-C and type-IC interactions. Second we have developed and implemented models for two-way coupling between the particle and fluid phase. This allows us to predict the reduced rate of turbulent mixing associated with particle dissipation of energy and similar phenomena. Work in characterizing these capabilities has taken place in homogeneous decaying turbulence, in free shear layers, in jets and in channel flow with walls, and selected results are presented.
Two classes of materials, poly(methylene diphenyl diisocyanate) or PMDI foam, and cross-linked epoxy resins, were characterized using thermal gravimetric analysis (TGA) and differential scanning calorimetry (DSC), to help understand the effects of aging and %E2%80%9Cbake-out%E2%80%9D. The materials were evaluated for mass loss and the onset of decomposition. In some experiments, volatile materials released during heating were analyzed via mass spectroscopy. In all, over twenty materials were evaluated to compare the mass loss and onset temperature for decomposition. Model free kinetic (MFK) measurements, acquired using variable heating rate TGA experiments, were used to calculate the apparent activation energy of thermal decomposition. From these compiled data the effects of aging, bake-out, and sample history on the thermal stability of materials were compared. No significant differences between aged and unaged materials were detected. Bake-out did slightly affect the onset temperature of decomposition but only at the highest bake-out temperatures. Finally, some recommendations for future handling are made.
Computers and Fluids
Abstract not provided.
The human brain (volume=1200cm3) consumes 20W and is capable of performing > 10^16 operations/s. Current supercomputer technology has reached 1015 operations/s, yet it requires 1500m^3 and 3MW, giving the brain a 10^12 advantage in operations/s/W/cm^3. Thus, to reach exascale computation, two achievements are required: 1) improved understanding of computation in biological tissue, and 2) a paradigm shift towards neuromorphic computing where hardware circuits mimic properties of neural tissue. To address 1), we will interrogate corticostriatal networks in mouse brain tissue slices, specifically with regard to their frequency filtering capabilities as a function of input stimulus. To address 2), we will instantiate biological computing characteristics such as multi-bit storage into hardware devices with future computational and memory applications. Resistive memory devices will be modeled, designed, and fabricated in the MESA facility in consultation with our internal and external collaborators.