Ca-Al-rich inclusions (CAIs) found in primitive chondrites record processes and conditions of the earliest solar system as they are the oldest known solid objects formed in the solar system [1,2]. CAIs with fractionation and unidentified nuclear anomalies (FUN CAIs; [3]) are very rare and thusfar found exclusively in CV carbonaceous chondrites (e.g., Allende and Vigarano)[4]. FUN CAIs are characterized by large nucleosynthetic anomalies in several elements (Ca, Ti, Si, Sr, Ba, Nd, and Sm), large mass-dependant isotope fractionation (Mg, Si, and O), and very little initial {sup 26}Al [4,5 and reference therein]. Formation of FUN CAIs by thermal processing of presolar dust aggregates prior to the injection of {sup 26}Al into the protoplanetary disk has been proposed. More recently [5] proposed that FUN CAIs formed from a protosolar molecular cloud after injection of {sup 26}Al but before {sup 26}Al and {sup 27}Al were completely homogenized. Therefore discovering more FUN CAIs to perform U-Pb and other short-lived chronometric dating will provide key constraints on the age of the solar system, the isotopic composition of the protosolar molecular cloud, the earliest stages of the thermal processing in the solar system and the timing of {sup 26}Al and other short-lived radionuclide injection into …

We present a data-parallel algorithm for identifying and labeling the connected sub-meshes within a domain-decomposed 3D mesh. The identification task is challenging in a distributed-memory parallel setting because connectivity is transitive and the cells composing each sub-mesh may span many or all processors. Our algorithm employs a multi-stage application of the Union-find algorithm and a spatial partitioning scheme to efficiently merge information across processors and produce a global labeling of connected sub-meshes. Marking each vertex with its corresponding sub-mesh label allows us to isolate mesh features based on topology, enabling new analysis capabilities. We briefly discuss two specific applications of the algorithm and present results from a weak scaling study. We demonstrate the algorithm at concurrency levels up to 2197 cores and analyze meshes containing up to 68 billion cells.

We use phase-resolved transient grating spectroscopy to measure the drift and diffusion of electron-hole density waves in a semiconductor quantum well. The unique aspects of this optical probe allow us to determine the frictional force between a two-dimensional Fermi liquid of electrons and a dilute gas of holes. Knowledge of electron-hole friction enables prediction of ambipolar dynamics in high-mobility electron systems.

In reference 1 the authors described {gamma}-ray holdup assay of a Mossbauer spectroscopy instrument where they utilized two axial symmetric cylindrical shell acquisitions and two disk source acquisitions to determine Am-241 and Np-237 contamination. The measured contents of the two species were determined using a general detector efficiency calibration taken from a 12-inch point source.2 The authors corrected the raw spectra for container absorption as well as for geometry corrections to transform the calibration curve to the applicable axial symmetric cylindrical source - and disk source - of contamination. The authors derived the geometry corrections with exact calculus that are shown in equations (1) and (2) of our Experimental section. A cylindrical shell (oven source) acquisition configuration is described in reference 3, where the authors disclosed this configuration to gain improved sensitivity for holdup measure of U-235 in a ten-chamber oven. The oven was a piece of process equipment used in the Savannah River Plant M-Area Uranium Fuel Fabrication plant for which a U-235 holdup measurement was necessary for its decontamination and decommissioning in 2003.4 In reference 4 the authors calibrated a bare NaI detector for these U-235 holdup measurements. In references 5 and 6 the authors calibrated a bare …

Large-scale carbon dioxide capture and storage (CCS) offers the benefit of reducing CO{sub 2} emissions and thereby mitigating climate change risk, but it will also bring its own health, safety, and environmental risks. Curtis M. Oldenburg, Editor-in-Chief, considers these risks in the context of the broader picture of energy production. Over the last year, there have been major acute health, safety, and environmental (HSE) consequences related to accidents involving energy production from every major primary energy source. These are, in chronological order: (i) the Upper Big Branch (coal) Mine disaster, (ii) the Gulf of Mexico Macondo (oil) well blowout, (iii) the San Bruno (natural gas) pipeline leak and explosion, and (iv) the Fukushima (nuclear) reactor radioactivity releases. Briefly, the Upper Big Branch Mine disaster occurred in West Virginia on April 5, 2010, when natural methane in the mine ignited, causing the deaths of 29 miners, the worst coal mine disaster in the USA since 1970. Fifteen days later, the Macondo oil well in the Gulf of Mexico suffered a blowout, with a gas explosion and fire on the floating drilling platform that killed 11 people. The oil and gas continued to flow out of the well at the seafloor until …

A long-standing goal of nuclear theory is to determine the properties of atomic nuclei based on the fundamental interactions among the protons and neutrons (i.e., nucleons). By adopting nucleon-nucleon (NN), three-nucleon (NNN) and higher-nucleon interactions determined from either meson-exchange theory or QCD, with couplings fixed by few-body systems, we preserve the predictive power of nuclear theory. This foundation enables tests of nature's fundamental symmetries and offers new vistas for the full range of complex nuclear phenomena. Basic questions that drive our quest for a microscopic predictive theory of nuclear phenomena include: (1) What controls nuclear saturation; (2) How the nuclear shell model emerges from the underlying theory; (3) What are the properties of nuclei with extreme neutron/proton ratios; (4) Can we predict useful cross sections that cannot be measured; (5) Can nuclei provide precision tests of the fundamental laws of nature; and (6) Under what conditions do we need QCD to describe nuclear structure, among others. Along with other ab initio nuclear theory groups, we have pursued these questions with meson-theoretical NN interactions, such as CD-Bonn and Argonne V18, that were tuned to provide high-quality descriptions of the NN scattering phase shifts and deuteron properties. We then add meson-theoretic NNN …

This paper seeks to understand what temporal and spatial scales of variability in global horizontal radiation are important to a PV plants and what measurements are needed to be able to characterize them. As solar radiation measuring instruments are point receivers it is important to understand how those measurements translate to energy received over a larger spatial extent. Also of importance is the temporal natural of variability over large spatial areas. In this research we use high temporal and spatial resolution measurements from multiple sensors at a site in Hawaii to create solar radiation fields at various spatial and temporal scales. Five interpolation schemes were considered and the high resolution solar fields were converted to power production for a PV power plant. It was found that the interpolation schemes are robust and create ramp distributions close to what would be computed if the average solar radiation field was used. We also investigated the possibility of using time averaged solar data from 1 sensor to recreate the ramp distribution from the 17 sensors. It was found that the ramping distribution from using appropriately time averaged data from 1 sensor can reasonably match the distribution created using the 17 sensor network.

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Thermophilic microbial communities that are active in a high-solids environment offer great potential for the discovery of industrially relevant enzymes that efficiently deconstruct bioenergy feedstocks. In this study, finished green waste compost was used as an inoculum source to enrich microbial communities and associated enzymes that hydrolyze cellulose and hemicellulose during thermophilic high-solids fermentation of the bioenergy feedstocks switchgrass and corn stover. Methods involving the disruption of enzyme and plant cell wall polysaccharide interactions were developed to recover xylanase and endoglucanase activity from deconstructed solids. Xylanase and endoglucanase activity increased by more than a factor of 5, upon four successive enrichments on switchgrass. Overall, the changes for switchgrass were more pronounced than for corn stover; solids reduction between the first and second enrichments increased by a factor of four for switchgrass while solids reduction remained relatively constant for corn stover. Amplicon pyrosequencing analysis of small-subunit ribosomal RNA genes recovered from enriched samples indicated rapid changes in the microbial communities between the first and second enrichment with the simplified communities achieved by the third enrichment. The results demonstrate a successful approach for enrichment of unique microbial communities and enzymes active in a thermophilic high-solids environment.

At the Modelica 2009 conference, we introduced the Buildings library, a freely available Modelica library for building energy and control systems. This paper reports the updates of the library and presents example applications for a range of heating, ventilation and air conditioning (HVAC) systems. Over the past two years, the library has been further developed. The number of HVAC components models has been doubled and various components have been revised to increase numerical robustness.The paper starts with an overview of the library architecture and a description of the main packages. To demonstrate the features of the Buildings library, applications that include multizone airflow simulation as well as supervisory and local loop control of a variable air volume (VAV) system are briefly described. The paper closes with a discussion of the current development.

2010 marked the emergence of the utility sector photovoltaic market. Utility sector photovoltaic installations quadrupled over 2009 installations. The share of utility sector installations of all U.S. grid-connected PV installations grew from virtually none in 2006 to 15 percent in 2009 and 32 percent in 2010. In addition, 2010 saw installation of a 75 MWAC concentrating solar power plant, the largest installed in the U.S. since 1991. In 2010, annual distributed grid-connected PV installations in the United States grew by 62 percent, to 606 MWDC. Photovoltaic arrays were installed at more than 50,000 sites in 2010, a 45 percent increase over the number of installations in 2009. Solar water heating installations increased by 6 percent in 2010, compared with 2009. Solar water heating has shown only two years of higher growth in the last 10 years. Solar pool heating installations increased by 13 percent in 2010, the largest growth in five years.

We present a derivation of the finite-size formulae in a moving frame with total momentum P=(2pi/L)(e_1+e_2). These formulae allow us to calculate the S-wave and P-wave scattering phases at more energies with a fixed lattice size and thus help us to determine the resonance parameters precisely.

Light trapping plays an important role to achieve high short circuit current density (Jsc) and high efficiency for amorphous/crystalline Si heterojunction solar cells. Si heterojunction uses hydrogenated amorphous Si for emitter and back contact. This structure of solar cell posses highest open circuit voltage of 0.747 V at one sun for c-Si based solar cells. It also suggests that over 25% record-high efficiency is possible with further improvement of Jsc. Light trapping has two important tasks. The first one is to reduce the surface reflectance of light to zero for the solar spectrum that Si has a response. The second one is to increase the effective absorption length to capture all the photon. For Si heterojunction solar cell, surface texturing, anti-reflectance indium tin oxides (ITO) layer at the front and back are the key area to improve the light trapping.

A key problem in making precise perturbative QCD predictions is the uncertainty in determining the renormalization scale of the running coupling {alpha}{sub s}({mu}{sup 2}). It is common practice to guess a physical scale {mu} = Q which is of order of a typical momentum transfer Q in the process, and then vary the scale over a range Q/2 and 2Q. This procedure is clearly problematic since the resulting fixed-order pQCD prediction will depend on the renormalization scheme, and it can even predict negative QCD cross sections at next-to-leading-order. Other heuristic methods to set the renormalization scale, such as the 'principle of minimal sensitivity', give unphysical results for jet physics, sum physics into the running coupling not associated with renormalization, and violate the transitivity property of the renormalization group. Such scale-setting methods also give incorrect results when applied to Abelian QED. Note that the factorization scale in QCD is introduced to match nonperturbative and perturbative aspects of the parton distributions in hadrons; it is present even in conformal theory and thus is a completely separate issue from renormalization scale setting. The PMC provides a consistent method for determining the renormalization scale in pQCD. The PMC scale-fixed prediction is independent of the …

There is enormous interest in visualizing the chemical composition of organic material that comprises our world. A convenient method to obtain molecular information with high spatial resolution is imaging mass spectrometry. However, the internal energy deposited within molecules upon transfer to the gas phase from a surface can lead to increased fragmentation and to complications in analysis of mass spectra. Here it is shown that in laser desorption with postionization by tunable vacuum ultraviolet (VUV) radiation, the internal energy gained during laser desorption leads to minimal fragmentation of DNA bases. The internal temperature of laser-desorbed triacontane molecules approaches 670 K, whereas the internal temperature of thymine is 800 K. A synchrotron-based VUV postionization technique for determining translational temperatures reveals that biomolecules have translational temperatures in the range of 216-346 K. The observed low translational temperatures, as well as their decrease with increased desorption laser power is explained by collisional cooling. An example of imaging mass spectrometry on an organic polymer, using laser desorption VUV postionization shows 5 mu m feature details while using a 30 mu m laser spot size and 7 ns duration. Applications of laser desorption postionization to the analysis of cellulose, lignin and humic acids are briefly …

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Crossflow filtration is a key process step in many operating and planned waste treatment facilities to separate undissolved solids from supernate slurries. This separation technology generally has the advantage of self cleaning through the action of wall shear stress, which is created by the flow of waste slurry through the filter tubes. However, the ability of filter wall self cleaning depends on the slurry being filtered. Many of the alkaline radioactive wastes are extremely challenging to filtration, e.g., those containing compounds of aluminum and iron, which have particles whose size and morphology reduces permeability. Low filter flux can be a bottleneck in waste processing facilities such as the Salt Waste Processing Facility at the Savannah River Site and the Waste Treatment Plant at the Hanford Site. Any improvement to the filtration rate would lead directly to increased throughput of the entire process. To date, increased rates are generally realized by either increasing the crossflow filter axial flowrate, which is limited by pump capacity, or by increasing filter surface area, which is limited by space and increases the required pump load. In the interest of accelerating waste treatment processing, DOE has funded studies to better understand filtration with the goal of …

Savannah River Remediation, LLC (SRR) is implementing a statistical sampling strategy for In-Service Inspection (ISI) of Liquid Waste (LW) Tanks at the United States Department of Energy's Savannah River Site (SRS) in Aiken, South Carolina. As a component of SRS's corrosion control program, the ISI program assesses tank wall structural integrity through the use of ultrasonic testing (UT). The statistical strategy for ISI is based on the random sampling of a number of vertically oriented unit areas, called strips, within each tank. The number of strips to inspect was determined so as to attain, over time, a high probability of observing at least one of the worst 5% in terms of pitting and corrosion across all tanks. The probability estimation to determine the number of strips to inspect was performed using the hypergeometric distribution. Statistical tolerance limits for pit depth and corrosion rates were calculated by fitting the lognormal distribution to the data. In addition to the strip sampling strategy, a single strip within each tank was identified to serve as the baseline for a longitudinal assessment of the tank safe operational life. The statistical sampling strategy enables the ISI program to develop individual profiles of LW tank wall structural …

Both powder particle size control and efficient use of gas flow energy are highly prized goals for gas atomization of metal and alloy powder to minimize off-size powder inventory (or 'reverb') and excessive gas consumption. Recent progress in the design of close-coupled gas atomization nozzles and the water model simulation of melt feed tubes were coupled with previous results from several types of gas flow characterization methods, e.g., aspiration measurements and gas flow visualization, to make progress toward these goals. Size distribution analysis and high speed video recordings of gas atomization reaction synthesis (GARS) experiments on special ferritic stainless steel alloy powders with an Ar+O{sub 2} gas mixture were performed to investigate the operating mechanisms and possible advantages of several melt flow tube modifications with one specific gas atomization nozzle. In this study, close-coupled gas atomization under closed wake gas flow conditions was demonstrated to produce large yields of ultrafine (dia.<20 {mu}m) powders (up to 32%) with moderate standard deviations (1.62 to 1.99). The increased yield of fine powders is consistent with the dual atomization mechanisms of closed wake gas flow patterns in the near-field of the melt orifice. Enhanced size control by stabilized pre-filming of the melt with a …

Greenhouse gas emissions from the forestry sector are estimated to be 8.4 GtCO2-eq./year or about 17percent of the global emissions. We estimate that the cost forreducing deforestation is low in Africa and several times higher in Latin America and Southeast Asia. These cost estimates are sensitive to the uncertainties of how muchunsustainable high-revenue logging occurs, little understood transaction and program implementation costs, and barriers to implementation including governance issues. Due to lack of capacity in the affected countries, achieving reduction or avoidance of carbon emissions will require extensive REDD-plus programs. Preliminary REDD-plus Readiness cost estimates and program descriptions for Indonesia, Democratic Republic of the Congo, Ghana, Guyana and Mexico show that roughly one-third of potential REDD-plus mitigation benefits might come from avoided deforestation and the rest from avoided forest degradation and other REDD-plus activities.

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An accelerated durability test method determined the potential impact of biodiesel ash impurities, including engine testing with multiple diesel particulate filter substrate types, as well as diesel oxidation catalyst and selective catalyst reduction catalysts. The results showed no significant degradation in the thermo-mechanical properties of a DPF after exposure to 150,000-mile equivalent biodiesel ash and thermal aging. However, exposure to 435,000-mile equivalent aging resulted in a 69% decrease in thermal shock resistance. A decrease in DOC activity was seen after exposure to 150,000-mile equivalent aging, resulting in higher hydrocarbon slip and a reduction in NO2 formation. The SCR catalyst experienced a slight loss in activity after exposure to 435,000-mile equivalent aging. The SCR catalyst, placed downstream of the DPF and exposed to B20 exhaust suffered a 5% reduction in overall NOx conversion activity over the HDDT test cycle. It is estimated that the additional ash from 150,000 miles of biodiesel use would also result in a moderate increases in exhaust backpressure for a DPF. The results of this study suggest that long-term operation with B20 at the current specification limits for alkali and alkaline earth metal impurities will adversely impact the performance of DOC, DPF and SCR systems.