National Library of Energy BETA

Sample records for homogeneous catalysis heterogeneous

  1. ISHHC XIII International Symposium on the Relations between Homogeneous and Heterogeneous Catalysis

    E-Print Network [OSTI]

    Somorjai Ed., G.A.

    2007-01-01

    K. Lee Semiconductor Photocatalysis in Advanced Oxidationthermal) catalysis or photocatalysis on nanoporous supportswith Heterogeneous Photocatalysis using Nanostructured

  2. ISHHC XIII International Symposium on the Relations betweenHomogeneous and Heterogeneous Catalysis

    SciTech Connect (OSTI)

    Somorjai , G.A.

    2007-06-11

    The International Symposium on Relations between Homogeneous and Heterogeneous Catalysis (ISHHC) has a long and distinguished history. Since 1974, in Brussels, this event has been held in Lyon, France (1977), Groeningen, The Netherlands (1981); Asilomar, California (1983); Novosibirsk, Russia (1986); Pisa, Italy (1989); Tokyo, Japan (1992); Balatonfuered, Hungary (1995); Southampton, United Kingdom (1999); Lyon, France (2001); Evanston, Illinois (2001) and Florence, Italy (2005). The aim of this international conference in Berkeley is to bring together practitioners in the three fields of catalysis, heterogeneous, homogeneous and enzyme, which utilize mostly nanosize particles. Recent advances in instrumentation, synthesis and reaction studies permit the nanoscale characterization of the catalyst systems, often for the same reaction, under similar experimental conditions. It is hoped that this circumstance will permit the development of correlations of these three different fields of catalysis on the molecular level. To further this goal we aim to uncover and focus on common concepts that emerge from nanoscale studies of structures and dynamics of the three types of catalysts. Another area of focus that will be addressed is the impact on and correlation of nanosciences with catalysis. There is information on the electronic and atomic structures of nanoparticles and their dynamics that should have importance in catalyst design and catalytic activity and selectivity.

  3. ISHHC XIII International Symposium on the Relations between Homogeneous and Heterogeneous Catalysis

    E-Print Network [OSTI]

    Somorjai Ed., G.A.

    2007-01-01

    Key Laboratory of Catalysis, Dalian Institute of ChemicalAcademy of Sciences, Dalian 116023, P. R. China CarbonApplied Catalysis Laboratory, Dalian Institute of Chemical

  4. Is It Homogeneous or Heterogeneous Catalysis Derived from [RhCp*Cl2]2? In Operando-XAFS, Kinetic and Crucial Kinetic Poisoning Evidence for Subnanometer Rh4 Cluster-Based Benzene Hydrogenation Catalysis

    SciTech Connect (OSTI)

    Bayram, Ercan; Linehan, John C.; Fulton, John L.; Roberts, John A.; Szymczak, Nathaniel; Smurthwaite, Tricia D.; Ozkar, Saim; Balasubramanian, Mahalingam; Finke, Richard G.

    2011-11-23

    Determining the true, kinetically dominant catalytically active species, in the classic benzene hydrogenation system pioneered by Maitlis and co-workers 34 years ago starting with [RhCp*Cl2]2 (Cp* = [{eta}5-C5(CH3)5]), has proven to be one of the most challenging case studies in the quest to distinguish single-metal-based 'homogeneous' from polymetallic, 'heterogeneous' catalysis. The reason, this study will show, is the previous failure to use the proper combination of (i) operando spectroscopy to determine the dominant form(s) of the precatalyst's mass under catalysis (i.e., operating) conditions, plus then and crucially also (ii) the previous lack of the necessary kinetic studies, catalysis being a 'wholly kinetic phenomenon' as J. Halpern long ago noted. An important contribution from this study will be to reveal the power of quantitiative kinetic poisoning experiments for distinguishing single-metal, or in this case subnanometer Rh4 cluster-based catalysis from larger, polymetallic Rh(0)n nanoparticle catalysis, at least under favorable conditions. The combined operando-XAFS (X-ray absorption fine structure) spectroscopy and kinetic evidences provide a compelling case for Rh4-based, with average stoichiometry 'Rh4Cp*2.4Cl4Hc', benzene hydrogenation catalysis in 2-propanol with added Et3N and at 100 C and 50 atm initial H2 pressure. The results also reveal, however, that if even ca. 1.4% of the total soluble Rh(0)n had formed nanoparticles, then those Rh(0)n nanoparticles would have been able to account for all the observed benzene hydrogenation catalytic rate (using commercial, ca. 2 nm, polyethyleneglycol-dodecylether hydrosol stabilized Rh(0)n nanoparticles as a model system). The results 'especially the poisoning methodology developed and employed' are of significant, broader interest since determining the nature of the true catalyst continues to be a central, often vexing issue in any and all catalytic reactions. The results are also of fundamental interest in that they add to a growing body of evidence indicating that certain, appropriately ligated, coordinatively unsaturated, subnanometer M4 transition-metal clusters can be relatively robust catalysts. Also demonstrated herein is that Rh4 clusters are poisoned by Hg(0), demonstrating for the first time that the classic Hg(0) poisoning test of 'homogeneous' vs 'heterogeneous'catalysts cannot distinguish Rh4-based subnanometer catalysts from Rh(0)n nanoparticle catalysts, at least for the present examples of these two specific, Rh-based catalysts.

  5. Reaction Selectivity in Heterogeneous Catalysis

    SciTech Connect (OSTI)

    Somorjai, Gabor A.; Kliewer, Christopher J.

    2009-02-02

    The understanding of selectivity in heterogeneous catalysis is of paramount importance to our society today. In this review we outline the current state of the art in research on selectivity in heterogeneous catalysis. Current in-situ surface science techniques have revealed several important features of catalytic selectivity. Sum frequency generation vibrational spectroscopy has shown us the importance of understanding the reaction intermediates and mechanism of a heterogeneous reaction, and can readily yield information as to the effect of temperature, pressure, catalyst geometry, surface promoters, and catalyst composition on the reaction mechanism. DFT calculations are quickly approaching the ability to assist in the interpretation of observed surface spectra, thereby making surface spectroscopy an even more powerful tool. HP-STM has revealed three vitally important parameters in heterogeneous selectivity: adsorbate mobility, catalyst mobility, and selective site-blocking. The development of size controlled nanoparticles from 0.8 to 10 nm, of controlled shape, and of controlled bimetallic composition has revealed several important variables for catalytic selectivity. Lastly, DFT calculations may be paving the way to guiding the composition choice for multi-metallic heterogeneous catalysis for the intelligent design of catalysts incorporating the many factors of selectivity we have learned.

  6. Homogeneous Catalysis Selective Oxidation of Methane to Methanol

    E-Print Network [OSTI]

    Goddard III, William A.

    Homogeneous Catalysis Selective Oxidation of Methane to Methanol Catalyzed, with CÀH Activation (generated by dissolution[6] of Au2O3) react with methane at 1808C to selectively generate methanol (as a mixture of the ester and methanol) in high yield (Table 1, entries 1 and 2). As expected, the irreversible

  7. Mechanisms and Design in Homogeneous Catalysis

    SciTech Connect (OSTI)

    Clark R. Landis

    2010-05-26

    The major goal of this research is the determination of structure-activity relationships with respect to the elementary reactions that constitute catalytic alkene polymerization. Three classes of structure-activity relationships pertain to this work: (1) The influence of the nature of the propagating alkyl (secondary, primary, ?-substituted) and alkene monomer on the rates and selectivity of propagation, termination, isomerization, hydrogenolysis, etc. Such analyses are possible by direct observation methods (2) Influence of Cp-ligand substituents on fundamental reaction steps by application of direct observation and quenched-flow methods (3) Influence of counterion and solvent polarity on rates and selectivities of elementary steps during polymerization. At this point our rate of progress is limited by a combination of inefficiencies in some data collection modes (particularly quenched-flow studies) and by a relatively narrow range of accessible rates (especially for the NMR methods). Therefore, the bulk of our work concerns the development NMR, mass spectrometric, and chromatographic methods for probing catalytic reactions in a high throughput mode. Although these methods will be applied in the context of alkene polymerization, the NMR and mass spectrometric methods are completely general and will benefit research in all areas of catalysis.

  8. Molecular-Level Design of Heterogeneous Chiral Catalysis

    SciTech Connect (OSTI)

    Francisco Zaera

    2012-03-21

    The following is a proposal to continue our multi-institutional research on heterogeneous chiral catalysis. Our team combines the use of surface-sensitive analytical techniques for the characterization of model systems with quantum and statistical mechanical calculations to interpret experimental data and guide the design of future research. Our investigation focuses on the interrelation among the three main mechanisms by which enantioselectivity can be bestowed to heterogeneous catalysts, namely: (1) by templating chirality via the adsorption of chiral supramolecular assemblies, (2) by using chiral modifiers capable of forming chiral complexes with the reactant and force enantioselective surface reactions, and (3) by forming naturally chiral surfaces using imprinting chiral agents. Individually, the members of our team are leaders in these various aspects of chiral catalysis, but the present program provides the vehicle to generate and exploit the synergies necessary to address the problem in a comprehensive manner. Our initial work has advanced the methodology needed for these studies, including an enantioselective titration procedure to identify surface chiral sites, infrared spectroscopy in situ at the interface between gases or liquids and solids to mimic realistic catalytic conditions, and DFT and Monte Carlo algorithms to simulate and understand chirality on surfaces. The next step, to be funded by the monies requested in this proposal, is to apply those methods to specific problems in chiral catalysis, including the identification of the requirements for the formation of supramolecular surface structures with enantioselective behavior, the search for better molecules to probe the chiral nature of the modified surfaces, the exploration of the transition from supramolecular to one-to-one chiral modification, the correlation of the adsorption characteristics of one-to-one chiral modifiers with their physical properties, in particular with their configuration, and the development of ways to imprint chiral centers on achiral solid surfaces. Chiral catalysis is not only a problem of great importance in its own right, but also the ultimate test of how to control selectivity in catalysis. The time is ripe for fundamental work in heterogeneous chiral catalysis to provide the U.S. with a leadership role in developing the next generation of catalytic processes for medicinal and agrochemical manufacturing. Our team provides the required expertise for a synergistic and comprehensive integration of physical and chemical experimentation with solid state and molecular reactivity theories to solve this problem.

  9. Percolation and homogenization theories for heterogeneous materials

    E-Print Network [OSTI]

    Chen, Ying, Ph. D. Massachusetts Institute of Technology

    2008-01-01

    Most materials produced by Nature and by human beings are heterogeneous. They contain domains of different states, structures, compositions, or material phases. How these different domains are distributed in space, or in ...

  10. Transformation of Sorbitol to Biofuels by Heterogeneous Catalysis: Chemical and Industrial

    E-Print Network [OSTI]

    Boyer, Edmond

    Transformation of Sorbitol to Biofuels by Heterogeneous Catalysis: Chemical and Industrial ainsi que des exemples d'applications industrielles. Abstract -- Transformation of Sorbitol to Biofuels and biodiesel production led to first generation biofuels. Nowadays, research is focused on lignocellulosic

  11. Application of solid ash based catalysts in heterogeneous catalysis

    SciTech Connect (OSTI)

    Shaobin Wang

    2008-10-01

    Solid wastes, fly ash, and bottom ash are generated from coal and biomass combustion. Fly ash is mainly composed of various metal oxides and possesses higher thermal stability. Utilization of fly ash for other industrial applications provides a cost-effective and environmentally friendly way of recycling this solid waste, significantly reducing its environmental effects. On the one hand, due to the higher stability of its major component, aluminosilicates, fly ash could be employed as catalyst support by impregnation of other active components for various reactions. On the other hand, other chemical compounds in fly ash such as Fe{sub 2}O{sub 3} could also provide an active component making fly ash a catalyst for some reactions. In this paper, physicochemical properties of fly ash and its applications for heterogeneous catalysis as a catalyst support or catalyst in a variety of catalytic reactions were reviewed. Fly-ash-supported catalysts have shown good catalytic activities for H{sub 2} production, deSOx, deNOx, hydrocarbon oxidation, and hydrocracking, which are comparable to commercially used catalysts. As a catalyst itself, fly ash can also be effective for gas-phase oxidation of volatile organic compounds, aqueous-phase oxidation of organics, solid plastic pyrolysis, and solvent-free organic synthesis. 107 refs., 4 figs., 2 tabs.

  12. Cryogenic homogenization and sampling of heterogeneous multi-phase feedstock

    DOE Patents [OSTI]

    Doyle, Glenn Michael (Lakewood, CO); Ideker, Virgene Linda (Arvada, CO); Siegwarth, James David (Boulder, CO)

    2002-01-01

    An apparatus and process for producing a homogeneous analytical sample from a heterogenous feedstock by: providing the mixed feedstock, reducing the temperature of the feedstock to a temperature below a critical temperature, reducing the size of the feedstock components, blending the reduced size feedstock to form a homogeneous mixture; and obtaining a representative sample of the homogeneous mixture. The size reduction and blending steps are performed at temperatures below the critical temperature in order to retain organic compounds in the form of solvents, oils, or liquids that may be adsorbed onto or absorbed into the solid components of the mixture, while also improving the efficiency of the size reduction. Preferably, the critical temperature is less than 77 K (-196.degree. C.). Further, with the process of this invention the representative sample may be maintained below the critical temperature until being analyzed.

  13. DOE Laboratory Catalysis Research Symposium - Abstracts

    SciTech Connect (OSTI)

    Dunham, T.

    1999-02-01

    The conference consisted of two sessions with the following subtopics: (1) Heterogeneous Session: Novel Catalytic Materials; Photocatalysis; Novel Processing Conditions; Metals and Sulfides; Nuclear Magnetic Resonance; Metal Oxides and Partial Oxidation; Electrocatalysis; and Automotive Catalysis. (2) Homogeneous Catalysis: H-Transfer and Alkane Functionalization; Biocatalysis; Oxidation and Photocatalysis; and Novel Medical, Methods, and Catalyzed Reactions.

  14. Analysis and optimization of heterogeneous materials using the variational asymptotic method for unit cell homogenization

    E-Print Network [OSTI]

    Yu, Wenbin

    1 Analysis and optimization of heterogeneous materials using the variational asymptotic method material and void are mixed artifi- cially. Keywords: Topology optimization; Homogenization method; Unit of the effective properties of periodically heterogeneous materials, within a periodic base cell. The sensitivities

  15. Charge Transfer and Support Effects in Heterogeneous Catalysis

    SciTech Connect (OSTI)

    Hervier, Antoine

    2011-12-21

    The kinetic, electronic and spectroscopic properties of two?dimensional oxide?supported catalysts were investigated in order to understand the role of charge transfer in catalysis. Pt/TiO{sub 2} nanodiodes were fabricated and used as catalysts for hydrogen oxidation. During the reaction, the current through the diode, as well as its I?V curve, were monitored, while gas chromatography was used to measure the reaction rate. The current and the turnover rate were found to have the same temperature dependence, indicating that hydrogen oxidation leads to the non?adiabatic excitation of electrons in Pt. A fraction of these electrons have enough energy to ballistically transport through Pt and overcome the Schottky barrier at the interface with TiO{sub 2}. The yield for this phenomenon is on the order of 10{sup ?4} electrons per product molecule formed, similar to what has been observed for CO oxidation and for the adsorption of many different molecules. The same Pt/TiO{sub 2} system was used to compare currents in hydrogen oxidation and deuterium oxidation. The current through the diode under deuterium oxidation was found to be greater than under hydrogen oxidation by a factor of three. Weighted by the difference in turnover frequencies for the two isotopes, this would imply a chemicurrent yield 5 times greater for D{sub 2} compared to H{sub 2}, contrary to what is expected given the higher mass of D{sub 2}. Reversible changes in the rectification factor of the diode are observed when switching between D{sub 2} and H{sub 2}. These changes are a likely cause for the differences in current between the two isotopes. In the nanodiode experiments, surface chemistry leads to charge flow, suggesting the possibility of creating charge flow to tune surface chemistry. This was done first by exposing a Pt/Si diode to visible light while using it as a catalyst for H{sub 2} oxidation. Absorption of the light in the Si, combined with the band bending at the interface, gives rise to a steady?state flow of hot holes to the surface. This leads to a decrease in turnover on the surface, an effect which is enhanced when a reverse bias is applied to the diode. Similar experiments were carried out for CO oxidation. On Pt/Si diodes, the reaction rate was found to increase when a forward bias was applied. When the diode was exposed to visible light and a reverse bias was applied, the rate was instead decreased. This implies that a flow of negative charges to the surface increases turnover, while positive charges decrease it. Charge flow in an oxide supported metal catalyst can be modified even without designing the catalyst as a solid state electronic device. This was done by doping stoichiometric and nonstoichiometric TiO{sub 2} films with F, and using the resulting oxides as supports for Pt films. In the case of stoichiometric TiO{sub 2}, F was found to act as an n?type dopant, creating a population of filled electronic states just below the conduction band, and dramatically increasing the conductivity of the oxide film. The electrons in those states can transfer to surface O, activating it for reaction with CO, and leading to increased turnover for CO oxidation. This reinforces the hypothesis that CO oxidation is activated by a flow of negative charges to the surface. The same set of catalysts was used for methanol oxidation. The electronic properties of the TiO{sub 2} films again correlated with the turnover rates, but also with selectivity. With stoichiometric TiO{sub 2} as the support, F?doping caused an increase in selectivity toward the formation of partial oxidation products, formaldehyde and methyl formate, versus the total oxidation product, CO{sub 2}. With non?stoichiometric TiO{sub 2}, F?doping had the reverse effect. Ambient Pressure X?Ray Photoelectron Spectroscopy was used to investigate this F?doping effect in reaction conditions. In O2 alone, and in CO oxidation conditions, the O1s spectrum showed a high binding energy peak that correlated in intensity with the activity of the different films: for stoichiomet

  16. Highly Dispersed Pseudo-Homogeneous and Heterogeneous Catalysts Synthesized via Inverse Micelle Solutions for the Liquefaction of Coal

    SciTech Connect (OSTI)

    Hampden-Smith, M.; Kawola, J.S.; Martino, A.; Sault, A.G.; Yamanaka, S.A.

    1999-01-05

    The mission of this project was to use inverse micelle solutions to synthesize nanometer sized metal particles and test the particles as catalysts in the liquefaction of coal and other related reactions. The initial focus of the project was the synthesis of iron based materials in pseudo-homogeneous form. The frost three chapters discuss the synthesis, characterization, and catalyst testing in coal liquefaction and model coal liquefaction reactions of iron based pseudo-homogeneous materials. Later, we became interested in highly dispersed catalysts for coprocessing of coal and plastic waste. Bifunctional catalysts . to hydrogenate the coal and depolymerize the plastic waste are ideal. We began studying, based on our previously devised synthesis strategies, the synthesis of heterogeneous catalysts with a bifunctional nature. In chapter 4, we discuss the fundamental principles in heterogeneous catalysis synthesis with inverse micelle solutions. In chapter 5, we extend the synthesis of chapter 4 to practical systems and use the materials in catalyst testing. Finally in chapter 6, we return to iron and coal liquefaction now studied with the heterogeneous catalysts.

  17. A numerical homogenization method for heterogeneous, anisotropic elastic media based on multiscale theory

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Gao, Kai; Chung, Eric T.; Gibson, Richard L.; Fu, Shubin; Efendiev, Yalchin

    2015-06-05

    The development of reliable methods for upscaling fine scale models of elastic media has long been an important topic for rock physics and applied seismology. Several effective medium theories have been developed to provide elastic parameters for materials such as finely layered media or randomly oriented or aligned fractures. In such cases, the analytic solutions for upscaled properties can be used for accurate prediction of wave propagation. However, such theories cannot be applied directly to homogenize elastic media with more complex, arbitrary spatial heterogeneity. We therefore propose a numerical homogenization algorithm based on multiscale finite element methods for simulating elasticmore »wave propagation in heterogeneous, anisotropic elastic media. Specifically, our method used multiscale basis functions obtained from a local linear elasticity problem with appropriately defined boundary conditions. Homogenized, effective medium parameters were then computed using these basis functions, and the approach applied a numerical discretization that is similar to the rotated staggered-grid finite difference scheme. Comparisons of the results from our method and from conventional, analytical approaches for finely layered media showed that the homogenization reliably estimated elastic parameters for this simple geometry. Additional tests examined anisotropic models with arbitrary spatial heterogeneity where the average size of the heterogeneities ranged from several centimeters to several meters, and the ratio between the dominant wavelength and the average size of the arbitrary heterogeneities ranged from 10 to 100. Comparisons to finite-difference simulations proved that the numerical homogenization was equally accurate for these complex cases.« less

  18. Analysis of the finite element heterogeneous multiscale method for nonlinear elliptic homogenization problems.

    E-Print Network [OSTI]

    Paris-Sud XI, Université de

    Analysis of the finite element heterogeneous multiscale method for nonlinear elliptic homogenization problems. Assyr Abdulle and Gilles Vilmart September 28, 2012 Abstract An analysis of the finite finite elements. Op- timal a-priori error estimates are obtained for the H1 and L2 norms, error bounds

  19. Surface functionalization of metal?organic polyhedron for homogeneous cyclopropanation catalysis

    SciTech Connect (OSTI)

    Lu, Weigang; Yuan, Daqiang; Yakovenko, Andrey; Zhou, Hong-Cai

    2012-03-13

    A super-paddlewheel (comprised of two paddlewheels) metal-organic polyhedron (MOP) containing surface hydroxyl groups was synthesized and characterized. Condensation reactions with linear alkyl anhydrides lead to new MOPs with enhanced solubility. As a result, the surface-modified MOP 4 was demonstrated as a homogeneous Lewis-acid catalyst.

  20. The performance of 3500 MWth homogeneous and heterogeneous metal fueled core designs

    SciTech Connect (OSTI)

    Turski, R.; Yang, Shi-tien

    1987-11-01

    Performance parameters are calculated for a representative 3500 MWth homogeneous and a heterogeneous metal fueled reactor design. The equilibrium cycle neutronic characteristics, safety coefficients, control system requirements, and control rod worths are evaluated. The thermal-hydraulic characteristics for both configurations are also compared. The heavy metal fuel loading requirements and neutronic performance characteristics are also evaluated for the uranium startup option. 14 refs., 14 figs., 20 tabs.

  1. ISHHC XIII International Symposium on the Relations between Homogeneous and Heterogeneous Catalysis

    E-Print Network [OSTI]

    Somorjai Ed., G.A.

    2007-01-01

    cuni.cz Palladium doped tin oxide powder exhibitspowder catalysts were prepared by impregnating nanostructural tin oxide particles with palladium

  2. ISHHC XIII International Symposium on the Relations between Homogeneous and Heterogeneous Catalysis

    E-Print Network [OSTI]

    Somorjai Ed., G.A.

    2007-01-01

    for Partial Oxidation of n-butane to Maleic Anhydride Y.H.catalytic activity of n-butane oxidation to maleic anhydrideconversion of methane with n-butane to give other alkanes.

  3. ISHHC XIII International Symposium on the Relations between Homogeneous and Heterogeneous Catalysis

    E-Print Network [OSTI]

    Somorjai Ed., G.A.

    2007-01-01

    90 (1986) 3890. P-4 Catalytic Oxidation of Tetralin Overa fundamental role in catalytic oxidation processes of manyshowed complete catalytic oxidation of CO by O 2 over the

  4. ISHHC XIII International Symposium on the Relations between Homogeneous and Heterogeneous Catalysis

    E-Print Network [OSTI]

    Somorjai Ed., G.A.

    2007-01-01

    Groups for the Synthesis of Bisphenol A” O3. Christopher W.for the Synthesis of Bisphenol A e Eric L. Margelefsky † ,for the production of Bisphenol A from acetone and phenol.

  5. ISHHC XIII International Symposium on the Relations between Homogeneous and Heterogeneous Catalysis

    E-Print Network [OSTI]

    Somorjai Ed., G.A.

    2007-01-01

    pyruvate, nitrobenzene, styrene, cyclohexanone, acetophenonefor the Oxidation of Styrene, Cyclohexene and Methyl Phenyland aromatic molecules such as styrene. Their mechanism of

  6. A microreactor system for high-pressure, multiphase homogeneous and heterogeneous catalyst measurements under continuous flow

    E-Print Network [OSTI]

    Keybl, Jaroslav

    2011-01-01

    The shift towards biomass and lower quality fossil fuel feedstocks will require new conversion approaches. Catalysis will be critical in the processing of these new feedstocks. By studying catalysis at industrially relevant ...

  7. Asymmetric Catalysis at the Mesoscale: Gold Nanoclusters Embedded in Chiral Self-Assembled Monolayer as Heterogeneous

    E-Print Network [OSTI]

    Asymmetric Catalysis at the Mesoscale: Gold Nanoclusters Embedded in Chiral Self of the catalytically active metallic sites and the surrounding chiral SAM for the formation of a mesoscale the catalytically active site from the nanoscale to the mesoscale, which implies a principle of operating systems

  8. Homogeneous and Heterogeneous Reaction and Transformation of Hg and Trace Metals in Combustion Systems

    SciTech Connect (OSTI)

    J. Helble; Clara Smith; David Miller

    2009-08-31

    The overall goal of this project was to produce a working dynamic model to predict the transformation and partitioning of trace metals resulting from combustion of a broad range of fuels. The information provided from this model will be instrumental in efforts to identify fuels and conditions that can be varied to reduce metal emissions. Through the course of this project, it was determined that mercury (Hg) and arsenic (As) would be the focus of the experimental investigation. Experiments were therefore conducted to examine homogeneous and heterogeneous mercury oxidation pathways, and to assess potential interactions between arsenic and calcium. As described in this report, results indicated that the role of SO{sub 2} on Hg oxidation was complex and depended upon overall gas phase chemistry, that iron oxide (hematite) particles contributed directly to heterogeneous Hg oxidation, and that As-Ca interactions occurred through both gas-solid and within-char reaction pathways. Modeling based on this study indicated that, depending upon coal type and fly ash particle size, vaporization-condensation, vaporization-surface reaction, and As-CaO in-char reaction all play a role in arsenic transformations under combustion conditions.

  9. Shining Light on Catalysis | Stanford Synchrotron Radiation Lightsourc...

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    A. van Bokhoven, Professor for Heterogeneous Catalysis Institute for Chemical and Bioengineering ETH Zurich Head of Laboratory for Catalysis and Sustainable Chemistry (LSK) Swiss...

  10. Multiscale thermoelastic analysis of random heterogeneous materials Part I: Microstructure characterization and homogenization of material properties

    E-Print Network [OSTI]

    Vel, Senthil

    characterization and homogenization of material properties Senthil S. Vel *, Andrew J. Goupee Department materials with random microstructure and understanding their thermomechanical properties. Realistic random mate- rial properties computed using the asymptotic expansion homogenization (AEH) method. The material

  11. Homogenization of a Conductive, Convective and Radiative Heat Transfer Problem in a Heterogeneous Domain

    E-Print Network [OSTI]

    Paris-Sud XI, Université de

    motivations for this study, we focus on its application to the nuclear reactor industry and especially-cooled reactor. It is typically made of many prismatic blocks of graphite in which are inserted the nuclear fuel by an homogeneous averaged (or effective, or homogenized) one. The goal of homogenization theory [8], [10], [15

  12. Comparison of Homogeneous and Heterogeneous CFD Fuel Models for Phase I of the IAEA CRP on HTR Uncertainties Benchmark

    SciTech Connect (OSTI)

    Gerhard Strydom; Su-Jong Yoon

    2014-04-01

    Computational Fluid Dynamics (CFD) evaluation of homogeneous and heterogeneous fuel models was performed as part of the Phase I calculations of the International Atomic Energy Agency (IAEA) Coordinate Research Program (CRP) on High Temperature Reactor (HTR) Uncertainties in Modeling (UAM). This study was focused on the nominal localized stand-alone fuel thermal response, as defined in Ex. I-3 and I-4 of the HTR UAM. The aim of the stand-alone thermal unit-cell simulation is to isolate the effect of material and boundary input uncertainties on a very simplified problem, before propagation of these uncertainties are performed in subsequent coupled neutronics/thermal fluids phases on the benchmark. In many of the previous studies for high temperature gas cooled reactors, the volume-averaged homogeneous mixture model of a single fuel compact has been applied. In the homogeneous model, the Tristructural Isotropic (TRISO) fuel particles in the fuel compact were not modeled directly and an effective thermal conductivity was employed for the thermo-physical properties of the fuel compact. On the contrary, in the heterogeneous model, the uranium carbide (UCO), inner and outer pyrolytic carbon (IPyC/OPyC) and silicon carbide (SiC) layers of the TRISO fuel particles are explicitly modeled. The fuel compact is modeled as a heterogeneous mixture of TRISO fuel kernels embedded in H-451 matrix graphite. In this study, a steady-state and transient CFD simulations were performed with both homogeneous and heterogeneous models to compare the thermal characteristics. The nominal values of the input parameters are used for this CFD analysis. In a future study, the effects of input uncertainties in the material properties and boundary parameters will be investigated and reported.

  13. HETEROGENEOUS CATALYSIS RESEARCH MEETING

    E-Print Network [OSTI]

    Authors, Various

    2011-01-01

    synthesis gas by coal gasification is very expensive andin the cost of coal gasification would have a significantthe feed derived from coal gasi.fication. To establish the

  14. HETEROGENEOUS CATALYSIS RESEARCH MEETING

    E-Print Network [OSTI]

    Authors, Various

    2011-01-01

    synthesis gas by coal gasification is very expensive andin the cost of coal gasification would have a significantas K co , to promote gasification would be beneficial s1nce

  15. HETEROGENEOUS CATALYSIS RESEARCH MEETING

    E-Print Network [OSTI]

    Authors, Various

    2011-01-01

    Coal Conversion Catalysts (Fred R. Brown) Solid State, Surface and Catalytic Propertiescoals. THE INFLUENCE f-ELECTRON CONFIGURATION ON CATALYTIC PROPERTIES

  16. HETEROGENEOUS CATALYSIS RESEARCH MEETING

    E-Print Network [OSTI]

    Authors, Various

    2011-01-01

    have been investigated: 1) catalytic oxidation of CO onPt and Pd1 2) catalytic oxidation of H2 on Pd; compet iveof the catalytic properties of oxides to specific oxidation

  17. HETEROGENEOUS CATALYSIS RESEARCH MEETING

    E-Print Network [OSTI]

    Authors, Various

    2011-01-01

    merits and disadvantages of LEED, Auger, photo- emissionelectron dif- fraction, (LEED), and the investigation of theof overlayer structures by LEED has concentrated on the

  18. Fabrication of Carbon-Platinum Interdigitated Array Electrodes and Their Application for Investigating Homogeneous Hydrogen Evolution Catalysis

    SciTech Connect (OSTI)

    Liu, Fei; Divan, Ralu; Parkinson, Bruce A.

    2015-06-29

    Carbon interdigitated array (IDA) electrodes have been applied to study the homogeneous hydrogen evolution electrocatalyst [Ni(PPh2NBn2)2]2+ (where PPh2NBn2 is 1,5-dibenzyl-3,7-diphenyl-1,5-diaza-3,7-diphosphacyclooctane). The existence of reaction intermediates in the catalytic cycle is inferred from the electrochemical behavior of a glassy carbon disk electrodes and carbon IDA electrodes. The currents on IDA electrodes for an EC’ (electron transfer reaction followed by a catalytic reaction) mechanism are derived from the number of redox cycles and the contribution of non-catalytic currents. The catalytic reaction rate constant was then extracted from the IDA current equations. Applying the IDA current and kinetic equations to the electrochemical response of the [Ni(PPh2NBn2)2]2+ catalyst yielded a rate constant of 0.10 s-1 for the hydrogen evolution reaction that agrees with the literature value. The quantitative analysis of IDA cyclic voltammetry can be used as a simple and straightforward method for determining rate constants in other catalytic systems. This work was supported as part of the Center for Molecular Electrocatalysis, an Energy Frontier Research Center funded by the Department of Energy, Office of Science, Office of Basic Energy Sciences. Pacific Northwest National Laboratory is operated by Battelle for DOE. Use of the Center for Nanoscale Materials was supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357.

  19. The public goods game on homogeneous and heterogeneous networks: investment strategy according to the pool size

    E-Print Network [OSTI]

    Zi-Gang Huang; Zhi-Xi Wu; Jian-Yue Guan; An-Cai Wu; Ying-Hai Wang

    2007-08-21

    We propose an extended public goods interaction model to study the evolution of cooperation in heterogeneous population. The investors are arranged on the well known scale-free type network, the Barab\\'{a}si-Albert model. Each investor is supposed to preferentially distribute capital to pools in its portfolio based on the knowledge of pool sizes. The extent that investors prefer larger pools is determined by investment strategy denoted by a tunable parameter $\\alpha$, with larger $\\alpha$ corresponding to more preference to larger pools. As comparison, we also study this interaction model on square lattice, and find that the heterogeneity contacts favors cooperation. Additionally, the influence of local topology to the game dynamics under different $\\alpha$ strategies are discussed. It is found that the system with smaller $\\alpha$ strategy can perform comparatively better than the larger $\\alpha$ ones.

  20. Supporting Information A Metal-Cluster-Based Heterogeneous Catalyst for Homogeneous

    E-Print Network [OSTI]

    for Homogeneous Catalytic Reactions: XAS and Reaction Kinetic Studies of their Activity Oxidation 1 Reduction 2 Oxidation 2 CN Pt-Pt 5.0 (0.5) 0.9 (0.1) 4.4 (0.4) 0.3 (0.1) CN Pt-Cl 0.3 (0.2) 2-factor 0.0064 0.0064 0.0051 0.0049 Table S2. The NEXAFS fitting parameters and R-factors for Oxidation 1

  1. Reaction Selectivity in Heterogeneous Catalysis

    E-Print Network [OSTI]

    Somorjai, Gabor A.

    2010-01-01

    G. A. Abstracts of Papers of the American Chemical SocietyG. A. Abstracts of Papers of the American Chemical Society

  2. INSTITUTE FOR INTEGRATED CATALYSIS Catalysis Research for

    E-Print Network [OSTI]

    . This work includes catalysis for upgrading biomass feedstocks; for chemical energy storage, retrieval

  3. Seventh BES (Basic Energy Sciences) catalysis and surface chemistry research conference

    SciTech Connect (OSTI)

    Not Available

    1990-03-01

    Research programs on catalysis and surface chemistry are presented. A total of fifty-seven topics are included. Areas of research include heterogeneous catalysis; catalysis in hydrogenation, desulfurization, gasification, and redox reactions; studies of surface properties and surface active sites; catalyst supports; chemical activation, deactivation; selectivity, chemical preparation; molecular structure studies; sorption and dissociation. Individual projects are processed separately for the data bases. (CBS)

  4. Frontiers in Catalysis Science and Engineering Seminar Series

    E-Print Network [OSTI]

    Engineering School of Chemistry and Biochemistry J. Carl & Sheila Pirkle Faculty Fellow Abstract Metal salenFrontiers in Catalysis Science and Engineering Seminar Series Heterogenized M-Salen Catalysts

  5. Combining X-ray Absorption and X-ray Diffraction Techniques for in Situ Studies of Chemical Transformations in Heterogeneous Catalysis: Advantages and Limitations

    SciTech Connect (OSTI)

    Frenkel, A.I.; Hanson, J.; Wang, Q.; Marinkovic, N.; Chen, J.G.; Barrio, L.; Si, R.; Lopez Camara, A.; Estrella, A.M.; Rodriguez, J.A.

    2011-08-05

    Recent advances in catalysis instrumentations include synchrotron-based facilities where time-resolved X-ray scattering and absorption techniques are combined in the same in situ or operando experiment to study catalysts at work. To evaluate the advances and limitations of this method, we performed a series of experiments at the new XAFS/XRD instrument in the National Synchrotron Light Source. Nearly simultaneous X-ray diffraction (XRD) and X-ray absorption fine-structure (XAFS) measurements of structure and kinetics of several catalysts under reducing or oxidizing conditions have been performed and carefully analyzed. For CuFe{sub 2}O{sub 4} under reducing conditions, the combined use of the two techniques allowed us to obtain accurate data on kinetics of nucleation and growth of metallic Cu. For the inverse catalyst CuO/CeO{sub 2} that underwent isothermal reduction (with CO) and oxidation (with O{sub 2}), the XAFS data measured in the same experiment with XRD revealed strongly disordered Cu species that went undetected by diffraction. These and other examples emphasize the unique sensitivity of these two complementary methods to follow catalytic processes in the broad ranges of length and time scales.

  6. Combining X-ray Absorption and X-ray Diffraction Techniques for in Situ Studies of Chemical Transformations in Heterogeneous Catalysis:Advantages and Limitations

    SciTech Connect (OSTI)

    A Frenkel; Q Wang; N Marinkovic; J Chen; L Barrio; R Si; A Lopez Camara; A Estella; J Rodriquez; J Hanson

    2011-12-31

    Recent advances in catalysis instrumentations include synchrotron-based facilities where time-resolved X-ray scattering and absorption techniques are combined in the same in situ or operando experiment to study catalysts at work. To evaluate the advances and limitations of this method, we performed a series of experiments at the new XAFS/XRD instrument in the National Synchrotron Light Source. Nearly simultaneous X-ray diffraction (XRD) and X-ray absorption fine-structure (XAFS) measurements of structure and kinetics of several catalysts under reducing or oxidizing conditions have been performed and carefully analyzed. For CuFe{sub 2}O{sub 4} under reducing conditions, the combined use of the two techniques allowed us to obtain accurate data on kinetics of nucleation and growth of metallic Cu. For the inverse catalyst CuO/CeO{sub 2} that underwent isothermal reduction (with CO) and oxidation (with O{sub 2}), the XAFS data measured in the same experiment with XRD revealed strongly disordered Cu species that went undetected by diffraction. These and other examples emphasize the unique sensitivity of these two complementary methods to follow catalytic processes in the broad ranges of length and time scales.

  7. Methanol Synthesis over Cu/ZnO/Al2O3: The Active Site in Industrial Catalysis

    SciTech Connect (OSTI)

    Behrens, Malte

    2012-03-28

    Unlike homogeneous catalysts, heterogeneous catalysts that have been optimized through decades are typically so complex and hard to characterize that the nature of the catalytically active site is not known. This is one of the main stumbling blocks in developing rational catalyst design strategies in heterogeneous catalysis. We show here how to identify the crucial atomic structure motif for the industrial Cu/ZnO/Al{sub 2}O{sub 3} methanol synthesis catalyst. Using a combination of experimental evidence from bulk-, surface-sensitive and imaging methods collected on real high-performance catalytic systems in combination with DFT calculations. We show that the active site consists of Cu steps peppered with Zn atoms, all stabilized by a series of well defined bulk defects and surface species that need jointly to be present for the system to work.

  8. The impact of nanoscience on heterogeneous catalysis

    SciTech Connect (OSTI)

    Bell, Alexis T.

    2003-03-03

    Most catalysts consist of nanometer-sized particles dispersed on a high-surface area support. Advances in characterization methods have led to a molecular level understanding of the relationships between nanoparticle properties and catalytic performance. Together with novel approaches to nanoparticle synthesis, this knowledge is contributing to the design and development of new catalysts.

  9. A Hydrogen-Evolving Ni(P2N2)2 Electrocatalyst Covalently Attached to a Glassy Carbon Electrode: Preparation, Characterization, and Catalysis. Comparisons With the Homogeneous Analog

    SciTech Connect (OSTI)

    Das, Atanu K.; Engelhard, Mark H.; Bullock, R. Morris; Roberts, John A.

    2014-07-07

    A hydrogen-evolving homogeneous Ni(P2N2)2 electrocatalyst with peripheral ester groups has been covalently attached to a 1,2,3-triazolyllithium-terminated glassy carbon electrode. The surface-confined complex is an electroctalyst for hydrogen evolution, showing onset of catalytic current at the same potential as the soluble parent complex. X-ray photoemission spectra show excellent agreement between the coupled and homogeneous species. Coverage approaches a dense monolayer. This research was supported as part of the Center for Molecular Electrocatalysis, an Energy Frontier Research Center funded by the US Department of Energy, Office of Science, Office of Basic Energy Sciences. Pacific Northwest National Laboratory is operated by Battelle for the US Department of Energy. The XPS measurements were performed at EMSL, a national scientific user facility sponsored by the Department of Energy's Office of Biological and Environmental Research and located at Pacific Northwest National Laboratory.

  10. Dendrimer-encapsulated metal nanoparticles: synthesis, characterization, and applications to catalysis 

    E-Print Network [OSTI]

    Niu, Yanhui

    2004-09-30

    The research in this dissertation examines the chemistry and applications of dendrimers in homogeneous catalysis. We examined interactions between dendrimers and charged probe molecules, prepared dendrimer-encapsulated metal nanoparticles...

  11. Homogeneous middles vs. heterogeneous tails, and the end of the ‘Inverted-U’: the share of the rich is what it's all about

    E-Print Network [OSTI]

    Palma, José Gabriel

    2011-01-26

    (D9), and [Y2]=right-hand axis (D10). 1=election of Allende; 2=Pinochet’s coup d’état; 3=the year Pinochet had to call a plebiscite seeking a mandate to remain in power for another eight years; 4=first democratic government (centre-left coalition... of the graph is Latin America’s median country (Peru=LA*). Evidence from Figure 11 indicates two noteworthy facts. One is the high degree of homogeneity across regions/countries regarding the share of income that the middle and upper-middle classes...

  12. Center for Catalysis at Iowa State University

    SciTech Connect (OSTI)

    Kraus, George A.

    2006-10-17

    The overall objective of this proposal is to enable Iowa State University to establish a Center that enjoys world-class stature and eventually enhances the economy through the transfer of innovation from the laboratory to the marketplace. The funds have been used to support experimental proposals from interdisciplinary research teams in areas related to catalysis and green chemistry. Specific focus areas included: • Catalytic conversion of renewable natural resources to industrial materials • Development of new catalysts for the oxidation or reduction of commodity chemicals • Use of enzymes and microorganisms in biocatalysis • Development of new, environmentally friendly reactions of industrial importance These focus areas intersect with barriers from the MYTP draft document. Specifically, section 2.4.3.1 Processing and Conversion has a list of bulleted items under Improved Chemical Conversions that includes new hydrogenation catalysts, milder oxidation catalysts, new catalysts for dehydration and selective bond cleavage catalysts. Specifically, the four sections are: 1. Catalyst development (7.4.12.A) 2. Conversion of glycerol (7.4.12.B) 3. Conversion of biodiesel (7.4.12.C) 4. Glucose from starch (7.4.12.D) All funded projects are part of a soybean or corn biorefinery. Two funded projects that have made significant progress toward goals of the MYTP draft document are: Catalysts to convert feedstocks with high fatty acid content to biodiesel (Kraus, Lin, Verkade) and Conversion of Glycerol into 1,3-Propanediol (Lin, Kraus). Currently, biodiesel is prepared using homogeneous base catalysis. However, as producers look for feedstocks other than soybean oil, such as waste restaurant oils and rendered animal fats, they have observed a large amount of free fatty acids contained in the feedstocks. Free fatty acids cannot be converted into biodiesel using homogeneous base-mediated processes. The CCAT catalyst system offers an integrated and cooperative catalytic system that performs both esterification (of free fatty acids) and transesterification (of soybean oil) in a one-pot fashion. This will allow the biodiesel producers to use the aforementioned cheap feedstocks without any pretreatment. In addition, the catalyst system is heterogeneous and is highly recyclable and reusable. Although markets currently exist for glycerin, concern is mounting that the price of glycerin may plummet to $.05 - $.10 per pound if future production exceeds demand. Developing a system to make high value chemicals such as 1,3-propanediol from the glycerin stream will add value for biodiesel producers who implement the new technology. Given the fact that both DuPont and Shell chemicals have announced the commercialization of two new PDO-based polymers, a rapid increase of market demand for a cheaper PDO source is very likely. 4. Comparison of actual accomplishments with goals and objectives From our progress reports, the four areas are: 1. Catalyst development (7.4.12.A) 2. Conversion of glycerol (7.4.12.B) 3. Conversion of biodiesel (7.4.12.C) 4. Glucose from starch (7.4.12.D)

  13. Surface Characterization of Heterogeneous Catalysts Using Low Energy Ion Scattering Spectroscopy Combined with Electrochemistry 

    E-Print Network [OSTI]

    Axnanda, Stephanus R.

    2010-07-14

    Fundamental studies of heterogeneous catalysis were performed and presented in this dissertation to gain a better understanding of heterogeneous catalytic reactions at a molecular level. Surface science techniques were ...

  14. Neutrons for Catalysis: A Workshop on Neutron Scattering Techniques for Studies in Catalysis

    SciTech Connect (OSTI)

    Overbury, Steven {Steve} H; Coates, Leighton; Herwig, Kenneth W; Kidder, Michelle

    2011-10-01

    This report summarizes the Workshop on Neutron Scattering Techniques for Studies in Catalysis, held at the Spallation Neutron Source (SNS) at Oak Ridge National Laboratory (ORNL) on September 16 and 17, 2010. The goal of the Workshop was to bring experts in heterogeneous catalysis and biocatalysis together with neutron scattering experimenters to identify ways to attack new problems, especially Grand Challenge problems in catalysis, using neutron scattering. The Workshop locale was motivated by the neutron capabilities at ORNL, including the High Flux Isotope Reactor (HFIR) and the new and developing instrumentation at the SNS. Approximately 90 researchers met for 1 1/2 days with oral presentations and breakout sessions. Oral presentations were divided into five topical sessions aimed at a discussion of Grand Challenge problems in catalysis, dynamics studies, structure characterization, biocatalysis, and computational methods. Eleven internationally known invited experts spoke in these sessions. The Workshop was intended both to educate catalyst experts about the methods and possibilities of neutron methods and to educate the neutron community about the methods and scientific challenges in catalysis. Above all, it was intended to inspire new research ideas among the attendees. All attendees were asked to participate in one or more of three breakout sessions to share ideas and propose new experiments that could be performed using the ORNL neutron facilities. The Workshop was expected to lead to proposals for beam time at either the HFIR or the SNS; therefore, it was expected that each breakout session would identify a few experiments or proof-of-principle experiments and a leader who would pursue a proposal after the Workshop. Also, a refereed review article will be submitted to a prominent journal to present research and ideas illustrating the benefits and possibilities of neutron methods for catalysis research.

  15. Magnetic Catalysis in Graphene

    E-Print Network [OSTI]

    Christopher Winterowd; Carleton DeTar; Savvas Zafeiropoulos

    2015-09-22

    One of the most important developments in condensed matter physics in recent years has been the discovery and characterization of graphene. A two-dimensional layer of Carbon arranged in a hexagonal lattice, graphene exhibits many interesting electronic properties, most notably that the low energy excitations behave as massless Dirac fermions. These excitations interact strongly via the Coulomb interaction and thus non-perturbative methods are necessary. Using methods borrowed from lattice QCD, we study the graphene effective theory in the presence of an external magnetic field. Graphene, along with other $(2+1)$-dimensional field theories, has been predicted to undergo spontaneous breaking of flavor symmetry including the formation of a gap as a result of the external magnetic field. This phenomenon is known as magnetic catalysis. Our study investigates magnetic catalysis using a fully non-perturbative approach.

  16. Magnetic Catalysis in Graphene

    E-Print Network [OSTI]

    Winterowd, Christopher; Zafeiropoulos, Savvas

    2015-01-01

    One of the most important developments in condensed matter physics in recent years has been the discovery and characterization of graphene. A two-dimensional layer of Carbon arranged in a hexagonal lattice, graphene exhibits many interesting electronic properties, most notably that the low energy excitations behave as massless Dirac fermions. These excitations interact strongly via the Coulomb interaction and thus non-perturbative methods are necessary. Using methods borrowed from lattice QCD, we study the graphene effective theory in the presence of an external magnetic field. Graphene, along with other $(2+1)$-dimensional field theories, has been predicted to undergo spontaneous breaking of flavor symmetry including the formation of a gap as a result of the external magnetic field. This phenomenon is known as magnetic catalysis. Our study investigates magnetic catalysis using a fully non-perturbative approach.

  17. Phase selectively soluble polymer supports to facilitate homogeneous catalysis 

    E-Print Network [OSTI]

    Ortiz-Acosta, Denisse

    2009-05-15

    and selectivity, and they often allow the use of mild reaction conditions. However, the metals used in the catalytic reactions most popular in organic synthesis like palladium, rhodium, and platinum are generally very expensive. The organic ligands...

  18. Polyisobutylene as a Polymer Support for Homogeneous Catalysis 

    E-Print Network [OSTI]

    Hongfa, Chayanant

    2010-01-14

    , a Hoveyda-Grubbs 2nd generation catalyst, and a N-heterocyclic carbene. The syntheses of these PIB-supported ligands and catalysts are simple and straightforward. The synthetic products and the intermediates in these syntheses can all be readily...

  19. Homogeneous Catalysis Selective Oxidation of Methane to Methanol

    E-Print Network [OSTI]

    Goddard III, William A.

    formed when SO3 or persulfate (K2S2O8) were added as possible oxidants of metallic gold (entries 5 and 6 oxidizing agent than SVI ions (Eo = 1.5 V SeO4 2À /H2SeO3, Eo = 0.17 V SO4 2À /H2SO3, respec- tively) and

  20. Homogeneous and Interfacial Catalysis in 3D Controlled Environment | The

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Homesum_a_epg0_fpd_mmcf_m.xls" ,"Available from WebQuantityBonneville Power Administration would likeUniverse (JournalvivoHigh energyHighland Viewdefault SignEnergy ScoreHomeAlamosAmes

  1. Electron Microscopy Catalysis Projects: Success Stories from...

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    Catalysis Projects: Success Stories from the High Temperature Materials Laboratory (HTML) User Program Electron Microscopy Catalysis Projects: Success Stories from the High...

  2. Catalysis Research for Energy Independence

    E-Print Network [OSTI]

    -conversions to significantly reduce the carbon footprint of the global energy system. We provide a fundamental understandingCatalysis Research for Energy Independence Chemical transformations are at the heart of energy production and use, and catalysis lies at the core of efficiently and effectively using our current energy

  3. Zeolite catalysis: technology

    SciTech Connect (OSTI)

    Heinemann, H.

    1980-07-01

    Zeolites have been used as catalysts in industry since the early nineteen sixties. The great majority of commercial applications employ one of three zeolite types: zeolite Y; Mordenite; ZSM-5. By far the largest use of zeolites is in catalytic cracking, and to a lesser extent in hydrocracking. This paper reviews the rapid development of zeolite catalysis and its application in industries such as: the production of gasoline by catalytic cracking of petroleum; isomerization of C/sub 5/ and C/sub 6/ paraffin hydrocarbons; alkylation of aromatics with olefins; xylene isomerization; and conversion of methanol to gasoline.

  4. Low-Temperature Hydrocarbon/CO Oxidation Catalysis in Support...

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    Catalysis in Support of HCCI Emission Control Low-Temperature HydrocarbonCO Oxidation Catalysis in Support of HCCI Emission Control Lean NOx Catalysis Research and Development...

  5. Elucidating the organic-OMS interface and its implications for heterogeneous catalysts 

    E-Print Network [OSTI]

    Wang, Qingqing

    2012-07-16

    Organic – ordered mesoporous silica (OMS) hybrid materials have attracted great interest due to their potential applications for gas separations, and heterogeneous catalysis. Amine-functionalized OMS materials are active in a variety of base...

  6. Catalysis by Confinement: Enthalpic Stabilization of NO Oxidation Transition States by Micropororous and Mesoporous Siliceous

    E-Print Network [OSTI]

    Iglesia, Enrique

    . INTRODUCTION The homogeneous oxidation of nitric oxide (NO) to nitrogen dioxide (NO2) with O2 as the oxidant transformation in selective catalytic NOx reduction (SCR) by NH3 on metal- exchanged zeolites7-11 and in NOxCatalysis by Confinement: Enthalpic Stabilization of NO Oxidation Transition States

  7. Recent advances of lanthanum-based perovskite oxides for catalysis

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Zhu, Huiyuan; Zhang, Pengfei; Dai, Sheng

    2015-09-21

    There is a need to reduce the use of noble metal elements especially in the field of catalysis, where noble metals are ubiquitously applied. To this end, perovskite oxides, an important class of mixed oxide, have been attracting increasing attention for decades as potential replacements. Benefiting from the extraordinary tunability of their compositions and structures, perovskite oxides can be rationally tailored and equipped with targeted physical and chemical properties e.g. redox behavior, oxygen mobility, and ion conductivity for enhanced catalysis. Recently, the development of highly efficient perovskite oxide catalysts has been extensively studied. This review article summarizes the recent developmentmore »of lanthanum-based perovskite oxides as advanced catalysts for both energy conversion applications and traditional heterogeneous reactions.« less

  8. Enhanced Micellar Catalysis LDRD.

    SciTech Connect (OSTI)

    Betty, Rita G.; Tucker, Mark David; Taggart, Gretchen; Kinnan, Mark K.; Glen, Crystal Chanea; Rivera, Danielle; Sanchez, Andres; Alam, Todd Michael

    2012-12-01

    The primary goals of the Enhanced Micellar Catalysis project were to gain an understanding of the micellar environment of DF-200, or similar liquid CBW surfactant-based decontaminants, as well as characterize the aerosolized DF-200 droplet distribution and droplet chemistry under baseline ITW rotary atomization conditions. Micellar characterization of limited surfactant solutions was performed externally through the collection and measurement of Small Angle X-Ray Scattering (SAXS) images and Cryo-Transmission Electron Microscopy (cryo-TEM) images. Micellar characterization was performed externally at the University of Minnesota's Characterization Facility Center, and at the Argonne National Laboratory Advanced Photon Source facility. A micellar diffusion study was conducted internally at Sandia to measure diffusion constants of surfactants over a concentration range, to estimate the effective micelle diameter, to determine the impact of individual components to the micellar environment in solution, and the impact of combined components to surfactant phase behavior. Aerosolized DF-200 sprays were characterized for particle size and distribution and limited chemical composition. Evaporation rates of aerosolized DF-200 sprays were estimated under a set of baseline ITW nozzle test system parameters.

  9. Catalysis Working Group Meeting: January 2015

    Broader source: Energy.gov [DOE]

    Agenda and presentations from the Catalysis Working Group meeting held January 21, 2015, in Los Alamos, New Mexico.

  10. Catalysis Working Group Meeting: June 2015

    Broader source: Energy.gov [DOE]

    Agenda and presentations from the Catalysis Working Group meeting held on June 8, 2015, in Arlington, Virginia.

  11. Fuel Synthesis Catalysis Laboratory (Fact Sheet)

    SciTech Connect (OSTI)

    Not Available

    2013-07-01

    This fact sheet provides information about Fuel Synthesis Catalysis Laboratory capabilities and applications at NREL's National Bioenergy Center.

  12. Heterogeneous effects in fast breeder reactors

    E-Print Network [OSTI]

    Gregory, Michael Vladimir

    1973-01-01

    Heterogeneous effects in fast breeder reactors are examined through development of simple but accurate models for the calculation of a posteriori corrections to a volume-averaged homogeneous representation. Three distinct ...

  13. Charge Transfer and Support Effects in Heterogeneous Catalysis

    E-Print Network [OSTI]

    Hervier, Antoine

    2012-01-01

    Support  for  Platinum in the Catalytic Oxidation of Carbon in  Hydrogen  and  Deuterium  Oxidation  on  Catalytic Platinum in  the Catalytic Oxidation of Carbon  Monoxide   

  14. Heterogeneous Catalysis DOI: 10.1002/anie.200503898

    E-Print Network [OSTI]

    Iglesia, Enrique

    , as in the reactions of isobutane on sulfated zirconia[14] and tert-butyl alcohol[5,7,8] on acidic ZSM5, MOR, BEA of Chemical Engineering University of California at Berkeley Berkeley, CA 94720 (USA) Fax: (+1)510-642-4778 E

  15. Heterogeneous Catalysis DOI: 10.1002/anie.200900541

    E-Print Network [OSTI]

    Iglesia, Enrique

    ) is a valuable fuel additive with a research octane number of 112. It can be produced with high selectivity from methanol (or dimethyl ether (DME)) using solutions of Zn[1­4] or In[5,6] halides at approximately 473 K triptane molecule formed per ZnI2.[2] Acid-catalyzed homologation of meth- anol/DME also occurs on zeolites

  16. Control Heterogeneous Catalysis at Atomic and Electronic-level Using

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Homesum_a_epg0_fpd_mmcf_m.xls" ,"Available from WebQuantityBonneville Power Administration would like submit the followingConcentrating DepartmentOIRVI4136Contracts &Trinity

  17. Textured Metal Catalysts for Heterogeneous Catalysis - Energy Innovation

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Homesum_a_epg0_fpd_mmcf_m.xls" ,"Available from WebQuantityBonneville Power AdministrationRobust,Field-effectWorking With U.S. CoalMexicoConferencePrice (DollarsPortal Biomass and

  18. Workshop: Synchrotron Applications in Chemical Catalysis | Stanford...

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Applications in Chemical Catalysis Tuesday, October 25, 2011 - 8:00am 2011 SSRLLCLS Annual Users Conference This workshop, part of the 2011 SSRLLCLS Annual Users...

  19. Basic Research Needs: Catalysis for Energy

    SciTech Connect (OSTI)

    Bell, Alexis T.; Gates, Bruce C.; Ray, Douglas; Thompson, Michael R.

    2008-03-11

    The report presents results of a workshop held August 6-8, 2007, by DOE SC Basic Energy Sciences to determine the basic research needs for catalysis research.

  20. Low-Temperature Hydrocarbon/CO Oxidation Catalysis in Support...

    Energy Savers [EERE]

    HydrocarbonCO Oxidation Catalysis in Support of HCCI Emission Control Low-Temperature HydrocarbonCO Oxidation Catalysis in Support of HCCI Emission Control Presentation from the...

  1. Plasma Assisted Catalysis System for NOx Reduction | Department...

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    Plasma Assisted Catalysis System for NOx Reduction Plasma Assisted Catalysis System for NOx Reduction 2002 DEER Conference Presentation: Noxtech, Inc. 2002deerslone.pdf More...

  2. Thermochemical Conversion: Using Heat and Catalysis to Make Biofuels...

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    Catalysis to Make Biofuels and Bioproducts The Bioenergy Technologies Office works with industry to develop pathways that use heat, pressure, and catalysis to convert domestic,...

  3. Modeling Biogeochemistry and Flow within Heterogeneous Formations in Variably-Saturated Media 

    E-Print Network [OSTI]

    Arora, Bhavna

    2012-10-19

    parameters. To evaluate the effect of heterogeneity on redox processes, repacked soil columns with homogeneous and heterogeneous (layered) profiles from soil cores collected at the Norman Landfill site, Oklahoma, USA were employed. Results indicate...

  4. Nanocrystal assembly for tandem catalysis

    DOE Patents [OSTI]

    Yang, Peidong; Somorjai, Gabor; Yamada, Yusuke; Tsung, Chia-Kuang; Huang, Wenyu

    2014-10-14

    The present invention provides a nanocrystal tandem catalyst comprising at least two metal-metal oxide interfaces for the catalysis of sequential reactions. One embodiment utilizes a nanocrystal bilayer structure formed by assembling sub-10 nm platinum and cerium oxide nanocube monolayers on a silica substrate. The two distinct metal-metal oxide interfaces, CeO.sub.2--Pt and Pt--SiO.sub.2, can be used to catalyze two distinct sequential reactions. The CeO.sub.2--Pt interface catalyzed methanol decomposition to produce CO and H.sub.2, which were then subsequently used for ethylene hydroformylation catalyzed by the nearby Pt--SiO.sub.2 interface. Consequently, propanal was selectively produced on this nanocrystal bilayer tandem catalyst.

  5. A BRIEF HISTORY OF INDUSTRIAL CATALYSIS

    E-Print Network [OSTI]

    Heinemann, Heinz

    2013-01-01

    A. Ethylene and its industrial derivatives. Ernst Bern,1974, 8(159). and its industrial Ernst Bern, 1973. u.s.A BRIEF HISTORY OF INDUSTRIAL CATALYSIS Heinz Heinemann TWO-

  6. Effective hydraulic conductivity of bounded, strongly heterogeneous porous media

    E-Print Network [OSTI]

    Tartakovsky, Daniel M.

    Effective hydraulic conductivity of bounded, strongly heterogeneous porous media Evangelos K of Arizona, Tucson Abstract. We develop analytical expressions for the effective hydraulic conductivity Ke boundaries. The log hydraulic conductivity Y forms a Gaussian, statistically homogeneous and anisotropic

  7. Homogenizing metamaterials, three times

    E-Print Network [OSTI]

    Didier Felbacq

    2012-11-08

    The homogenization of a metamaterial made of a collection of scatterers periodically disposed is studied from three different points of view. Specifically tools for multiple scattering theory, functional analysis, differential geometry and optimization are used. Detailed numerical results are given and the connections between the different approaches are enlightened.

  8. Study of catalysis of coal gasification at elevated pressures...

    Office of Scientific and Technical Information (OSTI)

    Study of catalysis of coal gasification at elevated pressures. Evaluation of 20 compounds at 850sup 0C Citation Details In-Document Search Title: Study of catalysis of coal...

  9. Geometrically induced magnetic catalysis and critical dimensions

    E-Print Network [OSTI]

    Antonino Flachi; Kenji Fukushima; Vincenzo Vitagliano

    2015-04-27

    We discuss the combined effect of magnetic fields and geometry in interacting fermionic systems. At leading order in the heat-kernel expansion, the infrared singularity (that in flat space leads to the magnetic catalysis) is regulated by the chiral gap effect, and the catalysis is deactivated by the effect of the scalar curvature. We discover that an infrared singularity is found in higher-order terms that mix the magnetic field with curvature, and these lead to a novel form of geometrically induced magnetic catalysis. The dynamical mass squared is then modified not only due to the chiral gap effect by an amount proportional to the curvature, but also by a magnetic shift $\\propto (4-D)eB$, where $D$ represents the number of space-time dimensions. We argue that $D=4$ is a critical dimension across which the behavior of the magnetic shift changes qualitatively.

  10. THE IMPACT OF DYNAMICALLY HETEROGENEOUS MULTICORE

    E-Print Network [OSTI]

    Sorin, Daniel J.

    -Core Opteron, Sun Microsystems' Niagara,2 and IBM's Power5.3 These pro- cessors have between two and eight SHOWS THAT OPERATING SYSTEM SCHEDULERS MUST CONSIDER DYNAMIC HETEROGENEITY OR SUFFER SIGNIFICANT POWER of homogeneous cores.6,7 With core special- ization, runtime fault handling, and power management, it is likely

  11. Homogenization in random media and effective medium theory for high frequency waves

    E-Print Network [OSTI]

    Bal, Guillaume

    Homogenization in random media and effective medium theory for high frequency waves Guillaume Bal May 1, 2007 Abstract We consider the homogenization of the wave equation with high frequency initial density of high frequency waves propagating in highly heterogeneous media when the wavelength is much

  12. Heterogeneity for Increasing Performance and Reliability of Self-Reconfigurable Multi-Robot Organisms

    E-Print Network [OSTI]

    Kernbach, S; Humza, R; Liedke, J; Popesku, S; Russo, S; Ranzani, T; Manfredi, L; Stefanini, C; Matthias, R; Schwarzer, Ch; Girault, B; Alschbach, P; Meister, E; Scholz, O

    2011-01-01

    Homogeneity and heterogeneity represent a well-known trade-off in the design of modular robot systems. This work addresses the heterogeneity concept, its rationales, design choices and performance evaluation. We introduce challenges for self-reconfigurable systems, show advances of mechatronic and software design of heterogeneous platforms and discuss experiments, which intend to demonstrate usability and performance of this system.

  13. Dynamic Economy with Heterogeneous Agents 

    E-Print Network [OSTI]

    Peng, Yulei

    2013-08-06

    [32], based on US data, show that compared with high income households, low income families use cash for a higher fraction of their total consumptions. By using the cash-in-advance model, Wen[85] shows that if the annual in ation rate is 10...%, households would like to recrease up to 15% of average con- sumption an annual year in order to obtain the Friedman rule in ation rate, which is signi cantly bigger than that of with considering homogeneous agents (Lucas [66]). Therefore, the heterogeneity...

  14. Homogeneous Gold Catalysis Highly Efficient Functionalization of CC Multiple Bonds and Electron-Rich CH Bonds

    E-Print Network [OSTI]

    Stoltz, Brian M.

    . Many mechanims proposed with the following chemistry, but it is important to note that in many cases

  15. End Functinalization of Polyisobutylenes and their Applications in Dyeing Polyolefins and in Homogeneous Catalysis 

    E-Print Network [OSTI]

    Boralugodage, Nilusha P

    2013-06-05

    oxidative and chemical resistance and nonpolar phase selective solubility of these modified PIB polymers allow these materials to be useful as soluble polymer supports for ligands and transition metal catalysts. This dissertation details immobilization...

  16. USD Catalysis Group for Alternative Energy

    SciTech Connect (OSTI)

    Hoefelmeyer, James D.; Koodali, Ranjit; Sereda, Grigoriy; Engebretson, Dan; Fong, Hao; Puszynski, Jan; Shende, Rajesh; Ahrenkiel, Phil

    2012-03-13

    The South Dakota Catalysis Group (SDCG) is a collaborative project with mission to develop advanced catalysts for energy conversion with two primary goals: (1) develop photocatalytic systems in which polyfunctionalized TiO2 are the basis for hydrogen/oxygen synthesis from water and sunlight (solar fuels group), (2) develop new materials for hydrogen utilization in fuel cells (fuel cell group). In tandem, these technologies complete a closed chemical cycle with zero emissions.

  17. Nanoscale Advances in Catalysis and Energy Applications

    SciTech Connect (OSTI)

    Li, Yimin; Somorjai, Gabor A.

    2010-05-12

    In this perspective, we present an overview of nanoscience applications in catalysis, energy conversion, and energy conservation technologies. We discuss how novel physical and chemical properties of nanomaterials can be applied and engineered to meet the advanced material requirements in the new generation of chemical and energy conversion devices. We highlight some of the latest advances in these nanotechnologies and provide an outlook at the major challenges for further developments.

  18. Low-Temperature Hydrocarbon/CO Oxidation Catalysis in Support...

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    of Energy Low-Temperature HydrocarbonCO Oxidation Catalysis in Support of HCCI Emission Control Ken Rapp, Liyu Li, Jonathan Male, Dave King Pacific Northwest National...

  19. Low-Temperature Hydrocarbon/CO Oxidation Catalysis in Support...

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    (OFCVT). deer07rappe.pdf More Documents & Publications Low-Temperature HydrocarbonCO Oxidation Catalysis in Support of HCCI Emission Control Selectlive Catalytic Reducution of...

  20. Blue Ruthenium Dimer Catalysis for Hydrogen Generation | Advanced...

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    to APS Science Highlights rss feed Blue Ruthenium Dimer Catalysis for Hydrogen Generation APRIL 15, 2013 Bookmark and Share Key intermediates in the water oxidation catalytic...

  1. Lean NOx Catalysis Research and Development | Department of Energy

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    Documents & Publications Lean-NOx Catalyst Development for Diesel Engine Applications Plasma-Activated Lean NOx Catalysis for Heavy-Duty Diesel Emissions Control Fuel Effects on...

  2. Catalysis by Design: Bridging the Gap between Theory and Experiments...

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    between Theory and Experiments Catalysis by Design: Bridging the Gap between Theory and Experiments Poster presentation at the 2007 Diesel Engine-Efficiency & Emissions Research...

  3. Catalysis by Design: Bridging the Gap Between Theory and Experiments...

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    Between Theory and Experiments at Nanoscale Level Catalysis by Design: Bridging the Gap Between Theory and Experiments at Nanoscale Level Studies on a simple platinum-alumina...

  4. Theoretical/Computational Tools for Energy-Relevant Catalysis...

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    TheoreticalComputational Tools for Energy-Relevant Catalysis FWPProject Description: Project Leader(s): James Evans, Mark Gordon Principal Investigators: James Evans, Mark Gordon...

  5. A BRIEF HISTORY OF INDUSTRIAL CATALYSIS

    E-Print Network [OSTI]

    Heinemann, Heinz

    2013-01-01

    Dealkylation Catalytic Coal Liquefaction and Gasification a)Liquefaction Gasification c) IX Methanation Heterogeneous~IQUEFACTION AND GASIFICATION a) Liquefaction Production of

  6. HARMONIC MORPHISMS ON HOMOGENEOUS HADAMARD

    E-Print Network [OSTI]

    Gudmundsson, Sigmundur

    HARMONIC MORPHISMS ON HOMOGENEOUS HADAMARD MANIFOLDS JONAS NORDSTRÃ?M Master's thesis 2010:E14;#12;Abstract In this thesis we investigate the existence of complex-valued harmonic morphisms on Lie groups of their Lie algebra. This decomposi- tion allows us to define harmonic morphisms to Rn , n 2. Any homogeneous

  7. Microgrids and Heterogeneous Power Quality and Reliability

    SciTech Connect (OSTI)

    LaCommare, Kristina; Marnay, Chris

    2007-10-01

    This paper describes two stylized alternative visions of how the power system might evolve to meet future requirements for the high quality electricity service that modern digital economies demand, a supergrids paradigm and a dispersed paradigm. Some of the economics of the dispersed vision are explored, and perspectives are presented on both the choice of homogeneous universal power quality upstream in the electricity supply chain and on the extremely heterogeneous requirements of end-use loads. It is argued that meeting the demanding requirements of sensitive loads by local provision of high quality power may be more cost effective than increasing the quality of universal homogeneous supply upstream in the legacy grid. Finally, the potential role of microgrids in delivering heterogeneous power quality is demonstrated by reference to two ongoing microgrid tests in the U.S. and Japan.

  8. Neutrons for Catalysis: A Workshop on Neutron Scattering Techniques for Studies in Catalysis

    E-Print Network [OSTI]

    Pennycook, Steve

    -EM Fischer Tropsch Catalysis on Fe- or Co-catalysts, ,,CTL" Coal to Liquids ­ ,a rough (?) analogy #12;Peter Albers, AQ-EM Carbonaceous Deposits on Catalysts #12;Peter Albers, AQ-EM IINS on Coked Catalysts from Industrial Plants High-temperature and low-temperature cokes deposited on catalysts during

  9. Lithium Diisopropylamide-Mediated Enolization: Catalysis by Hemilabile Ligands

    E-Print Network [OSTI]

    Collum, David B.

    Lithium Diisopropylamide-Mediated Enolization: Catalysis by Hemilabile Ligands Antonio Ramirez of a lithium diisopropylamide (LDA)-mediated ester enolization. Hemilabile amino ether MeOCH2CH2NMe2, binding-based catalysis are thwarted by the occlusion of the catalyst on the lithium salt products and byproducts (eq 1

  10. Dynamic control of catalysis within biological cells

    E-Print Network [OSTI]

    Biman Jana; Biman Bagchi

    2011-05-26

    We develop a theory of enzyme catalysis within biological cells where the substrate concentration [S](t) is time dependent, in contrast to the Michaelis-Menten theory that assumes a steady state. We find that the time varying concentration can combine, in a non-linear way, with the ruggedness of the free energy landscape of enzymes (discovered both in single molecule studies and in simulations) to provide a highly efficient switch (or, bifurcation) between two catalytically active states, at a critical substrate concentration. This allows a dynamic control of product synthesis in cell.

  11. Catalysis and Synthesis | Argonne National Laboratory

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Homesum_a_epg0_fpd_mmcf_m.xls" ,"Available from WebQuantity ofkandz-cm11 OutreachProductswsicloudwsiclouddenDVA N C E D B LReports fromSheetsCascadia AnalysisCatalysis and Synthesis

  12. Opportunities in Catalysis Research Using Synchrotron Radiation

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Homesum_a_epg0_fpd_mmcf_m.xls" ,"Available from WebQuantityBonneville Power Administration wouldMass mapSpeeding access toOctober 1996Technologies /JuneOperatingBusinessin Catalysis

  13. Impact of structured heterogeneities on reactive two-phase porous flow

    E-Print Network [OSTI]

    Reeves, Daniel

    Two-phase flow through heterogeneous media leads to scale-free distributions of irregularly shaped pockets of one fluid trapped within the other. Although reactions within these fluids are often modeled at the homogeneous ...

  14. Dispersion relations for acoustic waves in heterogeneous multi-layered structures contacting with

    E-Print Network [OSTI]

    Turova, Varvara

    Dispersion relations for acoustic waves in heterogeneous multi-layered structures contacting application for the computation of the velocity of acoustic waves excited in complicated multi: Multi-layered structures, Surface acoustic waves, Dispersion relations, Homogenization, Biosensor

  15. Intrinsic heterogeneity in the survival and proliferation capacities of naïve CD8? T cells

    E-Print Network [OSTI]

    Mahajan, Vinay Subhash

    2009-01-01

    This thesis describes the identification and characterization of a novel 'layer' of intrinsic non-genetic functional heterogeneity within the seemingly homogeneous naive CD8? T cell population in their survival and ...

  16. ChE 152, Winter 2015 Heterogeneous Kinetics and Reaction Engineering

    E-Print Network [OSTI]

    Low, Steven H.

    Graw-Hill, New York, 1981. 2. G.F. Froment and K.B. Bischoff, Chemical Reactor Analysis and Design, 2nd ed. Wiley, New York, 1990. 3. J.M. Thomas and W.J. Thomas, Principles and Practice of Heterogeneous Catalysis Reactors A. Dispersion (D&D, Chapter 8) B. Fixed-Bed Reactor Models (D&D, Chapter 10) C. Other

  17. Pointer Warping in Heterogeneous Multi-Monitor Environments Hrvoje Benko Steven Feiner

    E-Print Network [OSTI]

    Benko, Hrvoje

    Pointer Warping in Heterogeneous Multi-Monitor Environments Hrvoje Benko Steven Feiner Department and visual size alone. For mouse operation in a highly heterogeneous multi-monitor environment, all our in a homogeneous multi-monitor environment and showed significant improvements when traversing two or more monitor

  18. Multiscale asymptotic homogenization analysis of thermo-diffusive composite materials

    E-Print Network [OSTI]

    A. Bacigalupo; L. Morini; A. Piccolroaz

    2015-03-31

    In this paper an asymptotic homogenization method for the analysis of composite materials with periodic microstructure in presence of thermodiffusion is described. Appropriate down-scaling relations correlating the microscopic fields to the macroscopic displacements, temperature and mass concentration are introduced. The effects of the material inhomogeneities are described by perturbation functions derived from the solution of recursive cell problems. Exact expressions for the overall elastic and thermodiffusive constants of the equivalent first order thermodiffusive continuum are derived. The proposed approach is applied to the case of a two-dimensional bi-phase orthotropic layered material, where the effective elastic and thermodiffusive properties can be determined analytically. Considering this illustrative example and assuming periodic body forces, heat and mass sources acting on the medium, the solution performed by the first order homogenization approach is compared with the numerical results obtained by the heterogeneous model.

  19. Materials and interfaces for catalysis, separation, storage, and environmental applications

    E-Print Network [OSTI]

    Nair, Sankar

    the next generation of catalysts, separation processes, gas and liquid storage technologiesMaterials and interfaces for catalysis, separation, storage, and environmental applications Advanced materials and interfaces (including surfaces, thin films, and membranes) are a key to developing

  20. Catalysis Working Group Kick-Off Meeting Agenda

    Broader source: Energy.gov [DOE]

    Agenda for the kick-off meeting of the U.S. Department of Energy Fuel Cell Technologies Program's Catalysis Working Group, held May 14, 2012, in Arlington, Virginia.

  1. Theoretical investigation of solar energy conversion and water oxidation catalysis

    E-Print Network [OSTI]

    Wang, Lee-Ping

    2011-01-01

    Solar energy conversion and water oxidation catalysis are two great scientific and engineering challenges that will play pivotal roles in a future sustainable energy economy. In this work, I apply electronic structure ...

  2. Matrix Fourier transform in dynamic theory of elasticity of piecewise homogeneous medium

    E-Print Network [OSTI]

    O. Yaremko.; E. Mogileva

    2013-09-24

    The analytical solving dynamic problems of elasticity theory for piecewise homogeneous half-space is found. The explicit construction of direct and inverse Fourier's vector transform with discontinuous coefficients is presented. The technique of applying Fourier's vector transform with discontinuous coefficients for solving problems of mathematical physics in the heterogeneous environments is developed on an example of the dynamic problems of the elasticity theory.

  3. Homogeneous Random Measures and Strongly Supermedian Kernels

    E-Print Network [OSTI]

    Fitzsimmons, Patrick J.

    . Keywords and phrases: Homogeneous random measure, additive functional, Kuznets* *ov measure, potential

  4. Surfkin: A program to solve transient and steady state heterogeneous reaction kinetics

    SciTech Connect (OSTI)

    COLTRIN,MICHAEL E.; WIXOM,RYAN R.; DANDY,DAVID S.

    2000-05-01

    Heterogeneous chemical reactions occurring at a gas/surface interface are fundamental in a variety of important applications, such as combustion, catalysis, chemical vapor deposition and plasma processing. Detailed simulation of these processes may involve complex, coupled fluid flow, heat transfer, gas-phase chemistry, in addition to heterogeneous reaction chemistry. This report documents the Surfkin program, which simulates the kinetics of heterogeneous chemical reactions. The program is designed for use with the Chemkin and Surface Chemkin (heterogeneous chemistry) programs. It calculates time-dependent or steady state surface site fractions and bulk-species production/destruction rates. The surface temperature may be specified as a function of time to simulate a temperature-programmed desorption experiment, for example. This report serves as a user's manual for the program, explaining the required input and format of the output. Two detailed example problems are included to further illustrate the use of this program.

  5. Lean NOx Trap Catalysis for Lean Natural Gas Engine Applications

    SciTech Connect (OSTI)

    Parks, II, James E; Storey, John Morse; Theiss, Timothy J; Ponnusamy, Senthil; Ferguson, Harley Douglas; Williams, Aaron M; Tassitano, James B

    2007-09-01

    Distributed energy is an approach for meeting energy needs that has several advantages. Distributed energy improves energy security during natural disasters or terrorist actions, improves transmission grid reliability by reducing grid load, and enhances power quality through voltage support and reactive power. In addition, distributed energy can be efficient since transmission losses are minimized. One prime mover for distributed energy is the natural gas reciprocating engine generator set. Natural gas reciprocating engines are flexible and scalable solutions for many distributed energy needs. The engines can be run continuously or occasionally as peak demand requires, and their operation and maintenance is straightforward. Furthermore, system efficiencies can be maximized when natural gas reciprocating engines are combined with thermal energy recovery for cooling, heating, and power applications. Expansion of natural gas reciprocating engines for distributed energy is dependent on several factors, but two prominent factors are efficiency and emissions. Efficiencies must be high enough to enable low operating costs, and emissions must be low enough to permit significant operation hours, especially in non-attainment areas where emissions are stringently regulated. To address these issues the U.S. Department of Energy and the California Energy Commission launched research and development programs called Advanced Reciprocating Engine Systems (ARES) and Advanced Reciprocating Internal Combustion Engines (ARICE), respectively. Fuel efficiency and low emissions are two primary goals of these programs. The work presented here was funded by the ARES program and, thus, addresses the ARES 2010 goals of 50% thermal efficiency (fuel efficiency) and <0.1 g/bhp-hr emissions of oxides of nitrogen (NOx). A summary of the goals for the ARES program is given in Table 1-1. ARICE 2007 goals are 45% thermal efficiency and <0.015 g/bhp-hr NOx. Several approaches for improving the efficiency and emissions of natural gas reciprocating engines are being pursued. Approaches include: stoichiometric engine operation with exhaust gas recirculation and three-way catalysis, advanced combustion modes such as homogeneous charge compression ignition, and extension of the lean combustion limit with advanced ignition concepts and/or hydrogen mixing. The research presented here addresses the technical approach of combining efficient lean spark-ignited natural gas combustion with low emissions obtained from a lean NOx trap catalyst aftertreatment system. This approach can be applied to current lean engine technology or advanced lean engines that may result from related efforts in lean limit extension. Furthermore, the lean NOx trap technology has synergy with hydrogen-assisted lean limit extension since hydrogen is produced from natural gas during the lean NOx trap catalyst system process. The approach is also applicable to other lean engines such as diesel engines, natural gas turbines, and lean gasoline engines; other research activities have focused on those applications. Some commercialization of the technology has occurred for automotive applications (both diesel and lean gasoline engine vehicles) and natural gas turbines for stationary power. The research here specifically addresses barriers to commercialization of the technology for large lean natural gas reciprocating engines for stationary power. The report presented here is a comprehensive collection of research conducted by Oak Ridge National Laboratory (ORNL) on lean NOx trap catalysis for lean natural gas reciprocating engines. The research was performed in the Department of Energy's ARES program from 2003 to 2007 and covers several aspects of the technology. All studies were conducted at ORNL on a Cummins C8.3G+ natural gas engine chosen based on industry input to simulate large lean natural gas engines. Specific technical areas addressed by the research include: NOx reduction efficiency, partial oxidation and reforming chemistry, and the effects of sulfur poisons on the partial oxidation

  6. Dedicated Beamline Facilities for Catalytic Research. Synchrotron Catalysis Consortium (SCC)

    SciTech Connect (OSTI)

    Chen, Jingguang; Frenkel, Anatoly; Rodriguez, Jose; Adzic, Radoslav; Bare, Simon R.; Hulbert, Steve L.; Karim, Ayman; Mullins, David R.; Overbury, Steve

    2015-03-04

    Synchrotron spectroscopies offer unique advantages over conventional techniques, including higher detection sensitivity and molecular specificity, faster detection rate, and more in-depth information regarding the structural, electronic and catalytic properties under in-situ reaction conditions. Despite these advantages, synchrotron techniques are often underutilized or unexplored by the catalysis community due to various perceived and real barriers, which will be addressed in the current proposal. Since its establishment in 2005, the Synchrotron Catalysis Consortium (SCC) has coordinated significant efforts to promote the utilization of cutting-edge catalytic research under in-situ conditions. The purpose of the current renewal proposal is aimed to provide assistance, and to develop new sciences/techniques, for the catalysis community through the following concerted efforts: Coordinating the implementation of a suite of beamlines for catalysis studies at the new NSLS-II synchrotron source; Providing assistance and coordination for catalysis users at an SSRL catalysis beamline during the initial period of NSLS to NSLS II transition; Designing in-situ reactors for a variety of catalytic and electrocatalytic studies; Assisting experimental set-up and data analysis by a dedicated research scientist; Offering training courses and help sessions by the PIs and co-PIs.

  7. Dedicated heterogeneous node scheduling including backfill scheduling

    DOE Patents [OSTI]

    Wood, Robert R. (Livermore, CA); Eckert, Philip D. (Livermore, CA); Hommes, Gregg (Pleasanton, CA)

    2006-07-25

    A method and system for job backfill scheduling dedicated heterogeneous nodes in a multi-node computing environment. Heterogeneous nodes are grouped into homogeneous node sub-pools. For each sub-pool, a free node schedule (FNS) is created so that the number of to chart the free nodes over time. For each prioritized job, using the FNS of sub-pools having nodes useable by a particular job, to determine the earliest time range (ETR) capable of running the job. Once determined for a particular job, scheduling the job to run in that ETR. If the ETR determined for a lower priority job (LPJ) has a start time earlier than a higher priority job (HPJ), then the LPJ is scheduled in that ETR if it would not disturb the anticipated start times of any HPJ previously scheduled for a future time. Thus, efficient utilization and throughput of such computing environments may be increased by utilizing resources otherwise remaining idle.

  8. The Legend of Cosmological Homogeneity

    E-Print Network [OSTI]

    R. L. Oldershaw

    2008-05-17

    For more than a half century cosmologists have been guided by the assumption that matter is distributed homogeneously on sufficiently large scales. On the other hand, observations have consistently yielded evidence for inhomogeneity in the distribution of matter right up to the limits of most surveys. The apparent paradox can be understood in terms of the role that paradigms play in the evolution of science.

  9. Computational heterogeneous catalysis applied to steam methane reforming over nickel and nickel/silver catalysts

    E-Print Network [OSTI]

    Blaylock, Donnie Wayne

    2011-01-01

    The steam methane reforming (SMR) reaction is the primary industrial means for producing hydrogen gas. As such, it is a critical support process for applications including petrochemical processing and ammonia synthesis. ...

  10. Dynamic nuclear polarization solid-state NMR in heterogeneous catalysis research

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Kobayashi, Takeshi; Perras, Frédéric A.; Slowing, Igor I.; Sadow, Aaron D.; Pruski, Marek

    2015-10-20

    In this study, a revolution in solid-state nuclear magnetic resonance (SSNMR) spectroscopy is taking place, attributable to the rapid development of high-field dynamic nuclear polarization (DNP), a technique yielding sensitivity improvements of 2–3 orders of magnitude. This higher sensitivity in SSNMR has already impacted materials research, and the implications of new methods on catalytic sciences are expected to be profound.

  11. Major Successes of Theory-and-Experiment-Combined Studies in Surface Chemistry and Heterogeneous Catalysis.

    E-Print Network [OSTI]

    Somorjai, Gabor A.

    2011-01-01

    sensitive techniques such as LEED, XPS, AES, ISS and SIMS,crystallography[2, 3] (LEED) to high resolution electronincluding the development of LEED surface crystallography,

  12. Major Successes of Theory-and-Experiment-Combined Studies in Surface Chemistry and Heterogeneous Catalysis

    E-Print Network [OSTI]

    Somorjai, Gabor A.; Li, Yimin

    2010-01-01

    sensitive techniques such as LEED, XPS, AES, ISS and SIMS,crystallography [2, 3] (LEED) to high resolution electronincluding the development of LEED surface crystal- lography,

  13. New and Future Developments in Catalysis. Activation of Carbon Dioxide, 1st edition Supporting Information to Chapter 17

    E-Print Network [OSTI]

    Glaser, Rainer

    New and Future Developments in Catalysis. Activation of Carbon Dioxide, 1st Developments in Catalysis. Activation of Carbon Dioxide, 1st edition S2 Cartesian

  14. Some General Themes in Catalysis at LANL

    SciTech Connect (OSTI)

    Gordon, John C.

    2012-07-19

    Some general themes in catalysis at LANL are: (1) Storage and release of energy within chemical bonds (e.g. H{sub 2} storage in and release from covalent bonds, N{sub 2} functionalization, CO{sub 2} functionalization, H{sub 2} oxidation/evolution, O{sub 2} reduction/evolution); (2) Can we control the chemistry of reactive substrates to effect energy relevant transformations in non-traditional media (e.g. can we promote C-C couplings, dehydrations, or hydrogenations in water under relatively mild conditions)? (3) Can we supplant precious metal or rare earth catalysts to effect these transformations, by using earth abundant metals/elements instead? Can we use organocatalysis and circumvent the use of metals completely? (4) Can we improve upon existing rare earth catalyst systems (e.g. in rare earth oxides pertinent to fluid cracking or polymerization) and reduce amounts required for catalytic efficacy? Carbohydrates can be accessed from non-food based biomass sources such as woody residues and switchgrass. After extracted from the plant source, our goal is to upgrade these classes of molecules into useful fuels.

  15. Tomographic Characterization of Aquifer Heterogeneity

    E-Print Network [OSTI]

    Lyle, Shane

    2011-05-31

    ............................................................................................................................................ 26 Pumped Hydraulic Source – Monitoring Wells .................................................................................. 27 Pneumatic Source – Geoprobe... ......................................................................................................................................................... 96 Lateral Heterogeneity – Pumped Hydraulic CPT Source........................................................................ 97 Lateral Heterogeneity – Pneumatic CPT Source...

  16. Geek-Up[3.11.2011]: Energy Efficiency, Catalysis and Open Source...

    Energy Savers [EERE]

    Geek-Up3.11.2011: Energy Efficiency, Catalysis and Open Source Tools Geek-Up3.11.2011: Energy Efficiency, Catalysis and Open Source Tools March 11, 2011 - 4:37pm Addthis L....

  17. MRI of Heterogeneous Hydrogenation Reactions Using Parahydrogen Polarization

    SciTech Connect (OSTI)

    Burt, Scott R; Burt, Scott R.

    2008-06-25

    The power of magnetic resonance imaging (MRI) is its ability to image the internal structure of optically opaque samples and provide detailed maps of a variety of important parameters, such as density, diffusion, velocity and temperature. However, one of the fundamental limitations of this technique is its inherent low sensitivity. For example, the low signal to noise ratio (SNR) is particularly problematic for imaging gases in porous materials due to the low density of the gas and the large volume occluded by the porous material. This is unfortunate, as many industrially relevant chemical reactions take place at gas-surface interfaces in porous media, such as packed catalyst beds. Because of this severe SNR problem, many techniques have been developed to directly increase the signal strength. These techniques work by manipulating the nuclear spin populations to produce polarized} (i.e., non-equilibrium) states with resulting signal strengths that are orders of magnitude larger than those available at thermal equilibrium. This dissertation is concerned with an extension of a polarization technique based on the properties of parahydrogen. Specifically, I report on the novel use of heterogeneous catalysis to produce parahydrogen induced polarization and applications of this new technique to gas phase MRI and the characterization of micro-reactors. First, I provide an overview of nuclear magnetic resonance (NMR) and how parahydrogen is used to improve the SNR of the NMR signal. I then present experimental results demonstrating that it is possible to use heterogeneous catalysis to produce parahydrogen-induced polarization. These results are extended to imaging void spaces using a parahydrogen polarized gas. In the second half of this dissertation, I demonstrate the use of parahydrogen-polarized gas-phase MRI for characterizing catalytic microreactors. Specifically, I show how the improved SNR allows one to map parameters important for characterizing the heat and mass transport in a heterogeneous catalyst bed. This is followed by appendices containing detailed information regarding the design and use of my experimental setup.

  18. Superization of Homogeneous Spin Manifolds and Geometry of Homogeneous Supermanifolds

    E-Print Network [OSTI]

    Andrea Santi

    2009-05-24

    Let M_0=G_0/H be a (pseudo)-Riemannian homogeneous spin manifold, with reductive decomposition g_0=h+m and let S(M_0) be the spin bundle defined by the spin representation Ad:H->\\GL_R(S) of the stabilizer H. This article studies the superizations of M_0, i.e. its extensions to a homogeneous supermanifold M=G/H whose sheaf of superfunctions is isomorphic to Lambda(S^*(M_0)). Here G is the Lie supergroup associated with a certain extension of the Lie algebra of symmetry g_0 to an algebra of supersymmetry g=g_0+g_1=g_0+S via the Kostant-Koszul construction. Each algebra of supersymmetry naturally determines a flat connection nabla^{S} in the spin bundle S(M_0). Killing vectors together with generalized Killing spinors (i.e. nabla^{S}-parallel spinors) are interpreted as the values of appropriate geometric symmetries of M, namely even and odd Killing fields. An explicit formula for the Killing representation of the algebra of supersymmetry is obtained, generalizing some results of Koszul. The generalized spin connection nabla^{S} defines a superconnection on M, via the super-version of a theorem of Wang.

  19. Final technical report, Symposium on New Theoretical Concepts and Directions in Catalysis

    SciTech Connect (OSTI)

    Metiu, Horia

    2014-08-22

    We organized in August 2013 a “Symposium on New Theoretical Concepts and Directions in Catalysis” with the participation of 20 invited distinguished quantum chemists and other researchers who use computations to study catalysis. Symposium website; http://catalysis.cnsi.ucsb.edu/

  20. Pulsed Laser Powered Homogeneous Pyrolysis for

    E-Print Network [OSTI]

    Swihart, Mark T.

    Pulsed Laser Powered Homogeneous Pyrolysis for Reaction Kinetics Studies: Probe Laser Measurement Pulsed laser powered homogeneous pyrolysis ( LPHP) is a technique which can be used to measure rate a number of researchers have shown that pulsed laser powered homogeneous pyrolysis (LPHP) can be used

  1. Exhaust aftertreatment using plasma-assisted catalysis

    SciTech Connect (OSTI)

    Penetrante, B

    2000-01-20

    In the field of catalysis, one application that has been classified as a breakthrough technology is the catalytic reduction of NO{sub x} in oxygen-rich environments using hydrocarbons. This breakthrough will require dramatic improvements in both catalyst and engine technology, but the benefits will be substantial for energy efficiency and a cleaner environment. Engine and automobile companies are placing greater emphasis on the diesel engine because of its potential for saving fuel resources and reducing CO{sub 2} emissions. The modern direct-injection diesel engine offers demonstrated fuel economy advantages unmatched by any other commercially-viable engine. The main drawback of diesel engines is exhaust emissions. A modification of existing oxidation catalyst/engine technology is being used to address the CO, hydrocarbon and particulates. However, no satisfactory solution currently exists for NO{sub x}. Diesel engines operate under net oxidizing conditions, thus rendering conventional three-way catalytic converters ineffective for the controlling the NO{sub x} emission. NO{sub x} reduction catalysts, using ammonia as a reductant, do exist for oxygen-rich exhausts; however, for transportation applications, the use of on-board hydrocarbon fuels is a more feasible, cost-effective, and environmentally-sound approach. Selective catalytic reduction (SCR) by hydrocarbons is one of the leading catalytic aftertreatment technologies for the reduction of NO{sub x} in lean-burn engine exhaust (often referred to as lean-NO{sub x}). The objective is to chemically reduce the pollutant molecules of NO{sub x} to benign molecules such as N{sub 2}. Aftertreatment schemes have focused a great deal on the reduction of NO because the NO{sub x} in engine exhaust is composed primarily of NO. Recent studies, however, have shown that the oxidation of NO to NO{sub 2} serves an important role in enhancing the efficiency for reduction of NO{sub x} to N{sub 2}. It has become apparent that preconverting NO to NO{sub 2} could improve both the efficiency and durability of lean-NO{sub x} catalysts. A non-thermal plasma is an efficient means for selective partial oxidation of NO to NO{sub 2}. The use of a non-thermal plasma in combination with a lean-NO{sub x} catalyst opens the opportunity for catalysts that are more efficient and more durable compared to conventional catalysts. In the absence of hydrocarbons, the O radicals will oxidize NO to NO{sub 2}, and the OH radicals will further oxidize NO{sub 2} to nitric acid. In plasma-assisted catalysis it is important that the plasma oxidize NO to NO{sub 2} without further producing acids.

  2. Kinetics of Heterogeneous Ice Nucleation on the Surfaces of Mineral Dust Cores Inserted into Aqueous Ammonium Sulfate Particles

    E-Print Network [OSTI]

    Kinetics of Heterogeneous Ice Nucleation on the Surfaces of Mineral Dust Cores Inserted and absorb- ing terrestrial upwelling infrared radiation in the longwave.1 Unlike lower altitude clouds detailed know- ledge of both homogeneous and heterogeneous ice nucleation kinetics in the liquid phase.6

  3. Determining whether metals nucleate homogeneously on graphite: A case study with copper

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Appy, David; Lei, Huaping; Han, Yong; Wang, Cai -Zhuang; Tringides, Michael C.; Shao, Dahai; Kwolek, Emma J.; Evans, J. W.; Thiel, P. A.

    2014-11-05

    In this study, we observe that Cu clusters grow on surface terraces of graphite as a result of physical vapor deposition in ultrahigh vacuum. We show that the observation is incompatible with a variety of models incorporating homogeneous nucleation and calculations of atomic-scale energetics. An alternative explanation, ion-mediated heterogeneous nucleation, is proposed and validated, both with theory and experiment. This serves as a case study in identifying when and whether the simple, common observation of metal clusters on carbon-rich surfaces can be interpreted in terms of homogeneous nucleation. We describe a general approach for making system-specific and laboratory-specific predictions.

  4. Frontiers in Catalysis Science and Engineering Seminar Series

    E-Print Network [OSTI]

    Frontiers in Catalysis Science and Engineering Seminar Series H· Transfer from Transition-Metal Hydrides. Applications to Radical Polymerizations and Cyclizations Presented by... Jack R. Norton(II) metalloradical, but both the metalloradical and the hydride are present during the operation of newer (Cr

  5. Frontiers in Catalysis Science and Engineering Seminar Series

    E-Print Network [OSTI]

    of 5-HMF and derivatives Presented by... Prof. Z Conrad Zhang · Industrial Catalysis · Dalian Institute of Chemical Physics · Dalian, China Abstract One of the most notable advances toward biorefinery in recent. This talk covers the recent progress in three areas of research in my laboratory at the Dalian Institute

  6. JOURNAL OF CATALYSIS 177, 343351 (1998) ARTICLE NO. CA982143

    E-Print Network [OSTI]

    Iglesia, Enrique

    1998-01-01

    - modynamically favorable at high temperatures, but often leads to high yields of coke and smaller hydrocarbons, but it requires a selective catalyst in order to avoid complete oxidation to CO and CO2. A number of recentJOURNAL OF CATALYSIS 177, 343­351 (1998) ARTICLE NO. CA982143 Structure and Properties of Vanadium

  7. Lithium Diisopropylamide-Mediated Ortholithiations: Lithium Chloride Catalysis

    E-Print Network [OSTI]

    Collum, David B.

    Lithium Diisopropylamide-Mediated Ortholithiations: Lithium Chloride Catalysis Lekha Gupta, 2008 Ortholithiations of a range of arenes mediated by lithium diisopropylamide (LDA) in THF at -78 °C protocols with unpurified commercial samples of n-butyl- lithium to prepare LDA or commercially available

  8. SouthWest Catalysis Society 2011 Spring Symposium

    E-Print Network [OSTI]

    Natelson, Douglas

    , TX 77478 scott.mitchell@sabicusa.com Lin Luo The Dow Chemical Co. 2301 Brazosport Blvd. Freeport, TX of Texas A&M University to co-sponsor a symposium honoring Prof. Jack Lunsford for his accomplishments Award for Excellence in Applied Catalysis later in the day. On-site registration will begin at 7:30 AM

  9. Heterogeneous electrocatalysis in porous cathodes of solid oxide fuel cells

    E-Print Network [OSTI]

    Fu, Y; Bertei, A; Qi, C; Mohanram, A; Pietras, J D; Bazant, M Z

    2014-01-01

    A general physics-based model is developed for heterogeneous electrocatalysis in porous electrodes and used to predict and interpret the impedance of solid oxide fuel cells. This model describes the coupled processes of oxygen gas dissociative adsorption and surface diffusion of the oxygen intermediate to the triple phase boundary, where charge transfer occurs. The model accurately captures the Gerischer-like frequency dependence and the oxygen partial pressure dependence of the impedance of symmetric cathode cells. Digital image analysis of the microstructure of the cathode functional layer in four different cells directly confirms the predicted connection between geometrical properties and the impedance response. As in classical catalysis, the electrocatalytic activity is controlled by an effective Thiele modulus, which is the ratio of the surface diffusion length (mean distance from an adsorption site to the triple phase boundary) to the surface boundary layer length (square root of surface diffusivity div...

  10. Cyanide-catalyzed C-C bond formation: synthesis of novel compounds, materials and ligands for homogeneous catalysis 

    E-Print Network [OSTI]

    Reich, Blair Jesse Ellyn

    2007-04-25

    Cyanide-catalyzed aldimine coupling was employed to synthesize compounds with 1,2-ene-diamine and �±-imine-amine structural motifs: 1,2,N,N'- tetraphenyletheylene-1,2-diamine (13) and (+/-)-2,3-di-(2-hydroxyphenyl)-1,2 ...

  11. One- and two-dimensional infrared spectroscopic studies of solution-phase homogeneous catalysis and spin-forbidden reactions

    E-Print Network [OSTI]

    Sawyer, Karma Rae

    2010-01-01

    Fe(CO) 4 and 1 Fe(CO) 4 (ethane) compared to the results of1 Co(CO) (NO)(ethane). . . . . . 3 Co(CO) (4 and 1 Fe(CO) 4 (ethane). . . . . . . . 146 Ratio of the

  12. HOMOGENEOUS CATALYSIS AND MASS TRANSFER IN BIPHASIC IONIC LIQUID SYSTEMS WITH COMPRESSED CO2 AND ORGANIC COMPOUNDS

    E-Print Network [OSTI]

    Ahosseini, Azita

    with compressed CO2 and 1,1,1,2-tetrafluoroethane (R134a) are reported for further studies to choose the best media (ionic liquid/compressed gas) for reactions. Due to significant impacts of mass transfer on the reaction because of the high viscosity of ionic...

  13. Journal of Molecular Catalysis A: Chemical 251 (2006) 823 Design and study of homogeneous catalysts for the selective,

    E-Print Network [OSTI]

    Goddard III, William A.

    2006-01-01

    as groups have focused on the catalytic conversion of its major component, methane, to functionalized products. The key requirements is to design new catalysts for the oxidative functionalization of methane oxidation chemistry could lead to a new paradigm in petrochemical technology that is environmentally cleaner

  14. Synergism of Catalysis and Reaction Center Rehybridization. A Novel Mode of Catalysis in the Hydrolysis of Carbon Dioxide

    E-Print Network [OSTI]

    Lewis, Michael

    in the Hydrolysis of Carbon Dioxide Michael Lewis and Rainer Glaser* Contribution from the Department of Chemistry dioxide in carbonic anhydrase has long been an active area of research due to its fundamental importance-known that the hydrolysis of carbon dioxide in solution proceeds with catalysis from the solvent;3 however the structure

  15. This issue of Topics in Catalysis is devoted to ``Nanotechnology in Catalysis'' and covers some of the

    E-Print Network [OSTI]

    Resasco, Daniel

    silica, catalyst supports and catalytic membranes. Nanosized hollow spheres (silica or carbon) have been that generates the possibility of creating controlled porosity and molecular sieving effects. Gold nanoparticles attention by many catalysis research groups because of their very high carbon monoxide oxidation catalytic

  16. Persistent local order heterogeneity in the supercritical carbon dioxide

    E-Print Network [OSTI]

    Bolmatov, Dima; Gao, M; Zhernenkov, M

    2014-01-01

    The supercritical state is currently viewed as uniform and homogeneous on the pressure-temperature phase diagram in terms of physical properties. Here, we study structural properties of the supercritical carbon dioxide, and discover the existence of persistent medium-range order correlations which make supercritical carbon dioxide non-uniform and heterogeneous on an intermediate length scale, a result not hitherto anticipated. We report on the carbon dioxide heterogeneity shell structure where, in the first shell, both carbon and oxygen atoms experience gas-like type inter- actions with short range order correlations, while within the second shell oxygen atoms essentially exhibit liquid-like type of interactions with medium range order correlations due to localisation of transverse-like phonon packets. We show that the local order heterogeneity remains in the three phase-like equilibrium within very wide temperature range. Importantly, we highlight a catalytic role of atoms inside the nearest neighbor heterog...

  17. Homogeneous catalysts in hypersonic combustion

    SciTech Connect (OSTI)

    Harradine, D.M.; Lyman, J.L.; Oldenborg, R.C.; Pack, R.T.; Schott, G.L.

    1989-01-01

    Density and residence time both become unfavorably small for efficient combustion of hydrogen fuel in ramjet propulsion in air at high altitude and hypersonic speed. Raising the density and increasing the transit time of the air through the engine necessitates stronger contraction of the air flow area. This enhances the kinetic and thermodynamic tendency of H/sub 2/O to form completely, accompanied only by N/sub 2/ and any excess H/sub 2/(or O/sub 2/). The by-products to be avoided are the energetically expensive fragment species H and/or O atoms and OH radicals, and residual (2H/sub 2/ plus O/sub 2/). However, excessive area contraction raises air temperature and consequent combustion-product temperature by adiabatic compression. This counteracts and ultimately overwhelms the thermodynamic benefit by which higher density favors the triatomic product, H/sub 2/O, over its monatomic and diatomic alternatives. For static pressures in the neighborhood of 1 atm, static temperature must be kept or brought below ca. 2400 K for acceptable stability of H/sub 2/O. Another measure, whose requisite chemistry we address here, is to extract propulsive work from the combustion products early in the expansion. The objective is to lower the static temperature of the combustion stream enough for H/sub 2/O to become adequately stable before the exhaust flow is massively expanded and its composition ''frozen.'' We proceed to address this mechanism and its kinetics, and then examine prospects for enhancing its rate by homogeneous catalysts. 9 refs.

  18. AQUEOUS HOMOGENEOUS REACTORTECHNICAL PANEL REPORT

    SciTech Connect (OSTI)

    Diamond, D.J.; Bajorek, S.; Bakel, A.; Flanagan, G.; Mubayi, V.; Skarda, R.; Staudenmeier, J.; Taiwo, T.; Tonoike, K.; Tripp, C.; Wei, T.; Yarsky, P.

    2010-12-03

    Considerable interest has been expressed for developing a stable U.S. production capacity for medical isotopes and particularly for molybdenum- 99 (99Mo). This is motivated by recent re-ductions in production and supply worldwide. Consistent with U.S. nonproliferation objectives, any new production capability should not use highly enriched uranium fuel or targets. Conse-quently, Aqueous Homogeneous Reactors (AHRs) are under consideration for potential 99Mo production using low-enriched uranium. Although the Nuclear Regulatory Commission (NRC) has guidance to facilitate the licensing process for non-power reactors, that guidance is focused on reactors with fixed, solid fuel and hence, not applicable to an AHR. A panel was convened to study the technical issues associated with normal operation and potential transients and accidents of an AHR that might be designed for isotope production. The panel has produced the requisite AHR licensing guidance for three chapters that exist now for non-power reactor licensing: Reac-tor Description, Reactor Coolant Systems, and Accident Analysis. The guidance is in two parts for each chapter: 1) standard format and content a licensee would use and 2) the standard review plan the NRC staff would use. This guidance takes into account the unique features of an AHR such as the fuel being in solution; the fission product barriers being the vessel and attached systems; the production and release of radiolytic and fission product gases and their impact on operations and their control by a gas management system; and the movement of fuel into and out of the reactor vessel.

  19. THE KINEMATIC FORMULA IN RIEMANNIAN HOMOGENEOUS SPACES

    E-Print Network [OSTI]

    Howard, Ralph

    THE KINEMATIC FORMULA IN RIEMANNIAN HOMOGENEOUS SPACES Ralph Howard Department of Mathematics)IR (N). This generalizes the Chern-Federer kinematic formula to arbitrary homogeneous spaces with an invariant Riemannian metric and leads to new formulas even in the case of submanifolds of Euclidean space

  20. Analytic Coarse-Mesh Finite-Difference Method Generalized for Heterogeneous Multidimensional Two-Group Diffusion Calculations

    SciTech Connect (OSTI)

    Garcia-Herranz, Nuria [Universidad de Nacional de Educacion a Distancia (Spain); Cabellos, Oscar [Polytechnic University of Madrid (Spain); Aragones, Jose M. [Polytechnic University of Madrid (Spain); Ahnert, Carol [Polytechnic University of Madrid (Spain)

    2003-05-15

    In order to take into account in a more effective and accurate way the intranodal heterogeneities in coarse-mesh finite-difference (CMFD) methods, a new equivalent parameter generation methodology has been developed and tested. This methodology accounts for the dependence of the nodal homogeneized two-group cross sections and nodal coupling factors, with interface flux discontinuity (IFD) factors that account for heterogeneities on the flux-spectrum and burnup intranodal distributions as well as on neighbor effects.The methodology has been implemented in an analytic CMFD method, rigorously obtained for homogeneous nodes with transverse leakage and generalized now for heterogeneous nodes by including IFD heterogeneity factors. When intranodal mesh node heterogeneity vanishes, the heterogeneous solution tends to the analytic homogeneous nodal solution. On the other hand, when intranodal heterogeneity increases, a high accuracy is maintained since the linear and nonlinear feedbacks on equivalent parameters have been shown to be as a very effective way of accounting for heterogeneity effects in two-group multidimensional coarse-mesh diffusion calculations.

  1. Plasma-Activated Lean NOx Catalysis for Heavy-Duty Diesel Emissions...

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    Heavy-Duty NOx Emissions Control: Reformer-Assisted vs. Plasma-Facilitated Lean NOx Catalysis Selective reduction of NOx in oxygen rich environments with plasma-assisted...

  2. Support for U.S. Participants at the 15th International Congress on Catalysis

    SciTech Connect (OSTI)

    Wachs, Israel E.

    2013-08-05

    The grant was used to partially assist the travel expenses of U.S. academic scientists to attend the 15th International Congress on Catalysis. The conference was held in Munich, Germany from July 1-6, 2012. The importance of the International Congress was to bring together the international community of faculty members who participate in catalysis research, and to share information that would lead to further developments and directions in the field of study. Graduate students and Post Docs were invited to apply for travel assistance based on criteria established by the North American Catalysis Society (NACS) and the local Catalysis Clubs.

  3. KINETICS, CATALYSIS, AND REACTION ENGINEERING Staged O2 Introduction and Selective H2 Combustion during

    E-Print Network [OSTI]

    Iglesia, Enrique

    KINETICS, CATALYSIS, AND REACTION ENGINEERING Staged O2 Introduction and Selective H2 Combustion2 increased the selectivity of propane conversion to aromatics o

  4. Persistent local order heterogeneity in the supercritical carbon dioxide

    E-Print Network [OSTI]

    Dima Bolmatov; D. Zav'yalov; M. Gao; M. Zhernenkov

    2014-06-06

    The supercritical state is currently viewed as uniform and homogeneous on the pressure-temperature phase diagram in terms of physical properties. Here, we study structural properties of the supercritical carbon dioxide, and discover the existence of persistent medium-range order correlations which make supercritical carbon dioxide non-uniform and heterogeneous on an intermediate length scale, a result not hitherto anticipated. We report on the carbon dioxide heterogeneity shell structure where, in the first shell, both carbon and oxygen atoms experience gas-like type inter- actions with short range order correlations, while within the second shell oxygen atoms essentially exhibit liquid-like type of interactions with medium range order correlations due to localisation of transverse-like phonon packets. We show that the local order heterogeneity remains in the three phase-like equilibrium within very wide temperature range. Importantly, we highlight a catalytic role of atoms inside the nearest neighbor heterogeneity shell in providing a mechanism for diffusion in the supercritical carbon dioxide on an intermediate length scale. Finally, we discuss important implications for answering the intriguing question whether Venus may have had carbon dioxide oceans and urge for an experimental detection of this persistent local order heterogeneity.

  5. Monodisperse Platinum and Rhodium Nanoparticles as Model Heterogeneous Catalysts

    SciTech Connect (OSTI)

    Coble, Inger M

    2008-08-15

    Model heterogeneous catalysts have been synthesized and studied to better understand how the surface structure of noble metal nanoparticles affects catalytic performance. In this project, monodisperse rhodium and platinum nanoparticles of controlled size and shape have been synthesized by solution phase polyol reduction, stabilized by polyvinylpyrrolidone (PVP). Model catalysts have been developed using these nanoparticles by two methods: synthesis of mesoporous silica (SBA-15) in the presence of nanoparticles (nanoparticle encapsulation, NE) to form a composite of metal nanoparticles supported on SBA-15 and by deposition of the particles onto a silicon wafer using Langmuir-Blodgett (LB) monolayer deposition. The particle shapes were analyzed by transmission electron microscopy (TEM) and high resolution TEM (HRTEM) and the sizes were determined by TEM, X-ray diffraction (XRD), and in the case of NE samples, room temperature H2 and CO adsorption isotherms. Catalytic studies were carried out in homebuilt gas-phase reactors. For the nanoparticles supported on SBA-15, the catalysts are in powder form and were studied using the homebuilt systems as plug-flow reactors. In the case of nanoparticles deposited on silicon wafers, the same systems were operated as batch reactors. This dissertation has focused on the synthesis, characterization, and reaction studies of model noble metal heterogeneous catalysts. Careful control of particle size and shape has been accomplished though solution phase synthesis of Pt and Rh nanoparticles in order to elucidate further structure-reactivity relationships in noble metal catalysis.

  6. Multiscale strength homogenization : application to shale nanoindentation

    E-Print Network [OSTI]

    Gathier, Benjamin

    2008-01-01

    Shales are one of the most encountered materials in sedimentary basins. Because of their highly heterogeneous nature, their strength prediction for oil and gas exploitation engineering has long time been an enigma. In this ...

  7. A Saturation Algorithm for Homogeneous Binomial Ideals

    E-Print Network [OSTI]

    Mehta, Shashank K

    A Saturation Algorithm for Homogeneous Binomial Ideals Deepanjan Kesh and Shashank K Mehta Indian at computation in smaller rings is by Kesh and Mehta [7] which also requires the computation of one Gr

  8. STUDY OF THE MTC ESTIMATION BY NOISE ANALYSIS IN 2-D HETEROGENEOUS SYSTEMS

    E-Print Network [OSTI]

    Demazière, Christophe

    STUDY OF THE MTC ESTIMATION BY NOISE ANALYSIS IN 2-D HETEROGENEOUS SYSTEMS C. DEMAZIÈRE, I. PÁZSIT and Pázsit, 2002a). Nevertheless, this previous study only investigated 1-D one-group homogeneous systems. We propose here to perform a substantially more advanced study of the same problem in 2-D two-group diffusion

  9. The H-Cube Project: Hydrodynamics, Heterogeneity and Homogenization in CO2 storage modeling

    E-Print Network [OSTI]

    Paris-Sud XI, Université de

    descriptors), and in proposing suitable modeling and statistical workflows for assessing uncertainty analysis geological models typically contain many more cells than can be accommodated by reservoir simulation due studies of static earth reservoir models with different geological contexts [4]. References [1] Mouche E

  10. Ionization of large homogeneous and heterogeneous clusters generated in acetylene-Ar expansions: Cluster ion polymerization

    SciTech Connect (OSTI)

    Kocisek, J.; Lengyel, J.; Farnik, M.

    2013-03-28

    Pure acetylene and mixed Ar-acetylene clusters are formed in supersonic expansions of acetylene/argon mixtures and analysed using reflectron time-of-flight mass spectrometer with variable electron energy ionization source. Acetylene clusters composed of more than a hundred acetylene molecules are generated at the acetylene concentration of Almost-Equal-To 8%, while mixed species are produced at low concentrations ( Almost-Equal-To 0.7%). The electron energy dependence of the mass spectra revealed the ionization process mechanisms in clusters. The ionization above the threshold for acetylene molecule of 11.5 eV results in the main ionic fragment progression (C{sub 2}H{sub 2}){sub n}{sup +}. At the electron energies Greater-Than-Or-Slanted-Equal-To 21.5 eV above the CH+CH{sup +} dissociative ionization limit of acetylene the fragment ions nominally labelled as (C{sub 2}H{sub 2}){sub n}CH{sup +}, n Greater-Than-Or-Slanted-Equal-To 2, are observed. For n Less-Than-Or-Slanted-Equal-To 7 these fragments correspond to covalently bound ionic structures as suggested by the observed strong dehydrogenation [(C{sub 2}H{sub 2}){sub n}-k Multiplication-Sign H]{sup +} and [(C{sub 2}H{sub 2}){sub n}CH -k Multiplication-Sign H]{sup +}. The dehydrogenation is significantly reduced in the mixed clusters where evaporation of Ar instead of hydrogen can stabilize the nascent molecular ion. The C{sub 3}H{sub 3}{sup +} ion was previously assigned to originate from the benzene molecular ion; however, the low appearance energy of Almost-Equal-To 13.7 eV indicates that a less rigid covalently bound structure of C{sub 6}H{sub 6}{sup +} ion must also be formed upon the acetylene cluster electron ionization. The appearance energy of Ar{sub n}(C{sub 2}H{sub 2}){sup +} fragments above Almost-Equal-To 15.1 eV indicates that the argon ionization is the first step in the fragment ion production, and the appearance energy of Ar{sub n{>=}2}(C{sub 2}H{sub 2}){sub m{>=}2}{sup +} at Almost-Equal-To 13.7 eV is discussed in terms of an exciton transfer mechanism.

  11. Untangling the Chemical Evolution of Titan's Atmosphere and Surface -- From Homogeneous to Heterogeneous Chemistry

    E-Print Network [OSTI]

    Kaiser, Ralf I.

    2010-01-01

    CH 3 CCH), propane (C 3 H 8 ), diacetylene (C 4 H 2 ), andorganic solids (ethane, propane) with ionizing radiation insolid ices of ethane and propane – two of Titan’s abundant

  12. Untangling the Chemical Evolution of Titan's Atmosphere and Surface -- From Homogeneous to Heterogeneous Chemistry

    SciTech Connect (OSTI)

    Kaiser, Ralf I.; Maksyutenko, Pavlo; Ennis, Courtney; Zhang, Fangtong; Gu, Xibin; Krishtal, Sergey P.; Mebel, Alexander M.; Kostko, Oleg; Ahmed, Musahid

    2010-03-16

    The arrival of the Cassini-Huygens probe at Saturn's moon Titan - the only Solar System body besides Earth and Venus with a solid surface and a thick atmosphere with a pressure of 1.4 atm at surface level - in 2004 opened up a new chapter in the history of Solar System exploration. The mission revealed Titan as a world with striking Earth-like landscapes involving hydrocarbon lakes and seas as well as sand dunes and lava-like features interspersed with craters and icy mountains of hitherto unknown chemical composition. The discovery of a dynamic atmosphere and active weather system illustrates further the similarities between Titan and Earth. The aerosol-based haze layers, which give Titan its orange-brownish color, are not only Titan's most prominent optically visible features, but also play a crucial role in determining Titan's thermal structure and chemistry. These smog-like haze layers are thought to be very similar to those that were present in Earth's atmosphere before life developed more than 3.8 billion years ago, absorbing the destructive ultraviolet radiation from the Sun, thus acting as 'prebiotic ozone' to preserve astrobiologically important molecules on Titan. Compared to Earth, Titan's low surface temperature of 94 K and the absence of liquid water preclude the evolution of biological chemistry as we know it. Exactly because of these low temperatures, Titan provides us with a unique prebiotic 'atmospheric laboratory' yielding vital clues - at the frozen stage - on the likely chemical composition of the atmosphere of the primitive Earth. However, the underlying chemical processes, which initiate the haze formation from simple molecules, have been not understood well to date.

  13. 1 Electrospun Polyethylene Oxide/Cellulose Nanocrystal Composite 2 Nanofibrous Mats with Homogeneous and Heterogeneous

    E-Print Network [OSTI]

    , Ithaca, New York 14853, United States 7 bS Supporting Information 1. INTRODUCTION 25 Electrospinning of an all-aqueous system for electrospinning based 64on a combination of CNCs with water-soluble polymers biodegradable, and Received: March 23, 2011 Revised: May 5, 2011 8 ABSTRACT: An electrospinning process

  14. Untangling the Chemical Evolution of Titan's Atmosphere and Surface -- From Homogeneous to Heterogeneous Chemistry

    E-Print Network [OSTI]

    Kaiser, Ralf I.

    2010-01-01

    The A output of the PDGI pulse generator (TTL, high impe-generator (PDG II). The time delayed A output (A = T 0 +16,666.66 ?s, high

  15. Hydrogen catalysis and scavenging action of Pd-POSS nanoparticles

    SciTech Connect (OSTI)

    Maiti, A; Gee, R H; Maxwell, R; Saab, A

    2007-02-01

    Prompted by the need for a self-supported, chemically stable, and functionally flexible catalytic nanoparticle system, we explore a system involving Pd clusters coated with a monolayer of polyhedral oligomeric silsesquioxane (POSS) cages. With an initial theoretical focus on hydrogen catalysis and sequestration in the Pd-POSS system, we report Density Functional Theory (DFT) results on POSS binding energies to the Pd(110) surface, hydrogen storing ability of POSS, and possible pathways of hydrogen radicals from the catalyst surface to unsaturated bonds away from the surface.

  16. Inorganic Chemistry in Hydrogen Storage and Biomass Catalysis

    SciTech Connect (OSTI)

    Thorn, David [Los Alamos National Laboratory

    2012-06-13

    Making or breaking C-H, B-H, C-C bonds has been at the core of catalysis for many years. Making or breaking these bonds to store or recover energy presents us with fresh challenges, including how to catalyze these transformations in molecular systems that are 'tuned' to minimize energy loss and in molecular and material systems present in biomass. This talk will discuss some challenging transformations in chemical hydrogen storage, and some aspects of the inorganic chemistry we are studying in the development of catalysts for biomass utilization.

  17. USD Catalysis Group for Alternative Energy - Final report

    SciTech Connect (OSTI)

    Hoefelmeyer, James

    2014-10-03

    I. Project Summary Catalytic processes are a major technological underpinning of modern society, and are essential to the energy sector in the processing of chemical fuels from natural resources, fine chemicals synthesis, and energy conversion. Advances in catalyst technology are enormously valuable since these lead to reduced chemical waste, reduced energy loss, and reduced costs. New energy technologies, which are critical to future economic growth, are also heavily reliant on catalysts, including fuel cells and photo-electrochemical cells. Currently, the state of South Dakota is underdeveloped in terms of research infrastructure related to catalysis. If South Dakota intends to participate in significant economic growth opportunities that result from advances in catalyst technology, then this area of research needs to be made a high priority for investment. To this end, a focused research effort is proposed in which investigators from The University of South Dakota (USD) and The South Dakota School of Mines and Technology (SDSMT) will contribute to form the South Dakota Catalysis Group (SDCG). The multidisciplinary team of the (SDCG) include: (USD) Dan Engebretson, James Hoefelmeyer, Ranjit Koodali, and Grigoriy Sereda; (SDSMT) Phil Scott Ahrenkiel, Hao Fong, Jan Puszynski, Rajesh Shende, and Jacek Swiatkiewicz. The group is well suited to engage in a collaborative project due to the resources available within the existing programs. Activities within the SDCG will be monitored through an external committee consisting of three distinguished professors in chemistry. The committee will provide expert advice and recommendations to the SDCG. Advisory meetings in which committee members interact with South Dakota investigators will be accompanied by individual oral and poster presentations in a materials and catalysis symposium. The symposium will attract prominent scientists, and will enhance the visibility of research in the state of South Dakota. The SDCG requests funding through the Department of Energy (DoE) to establish this multidisciplinary research cluster in the area of catalysis. This long-term approach includes synthesis, characterization, catalyst evaluation, modeling, and scale-up. The project includes plans to acquire instrumentation critical to enabling competitive research. These acquisitions will complement existing resources in the state. The effect of implementation of the proposed efforts will be to significantly enhance state infrastructure in personnel and equipment, and lead to a nationally and internationally recognized research center.

  18. Quark Antiscreening at Strong Magnetic Field and Inverse Magnetic Catalysis

    E-Print Network [OSTI]

    E. J. Ferrer; V. de la Incera; X. J. Wen

    2015-02-17

    The dependence of the QCD coupling constant with a strong magnetic field and the implications for the critical temperature of the chiral phase transition are investigated. It is found that the coupling constant becomes anisotropic in a strong magnetic field and that the quarks, confined by the field to the lowest Landau level where they pair with antiquarks, produce an antiscreening effect. These results lead to inverse magnetic catalysis, providing a natural explanation for the behavior of the critical temperature in the strong-field region.

  19. Application of cryogenic grinding to achieve homogenization of transuranic wastes

    SciTech Connect (OSTI)

    Atkins, W.H.; Hill, D.D.; Lucero, M.E.; Jaramillo, L.; Martinez, H.E.

    1996-08-01

    This paper describes work done at Los Alamos National Laboratory (LANL) in collaboration with the Department of Energy Rocky Flats Field Office (DOE/RFFO) and with the National Institute of Standards and Technology (NIST), Boulder, Colorado. Researchers on this project have developed a method for cryogenic grinding of mixed wastes to homogenize and, thereby, to acquire a representative sample of the materials. There are approximately 220,000 waste drums owned by the Rocky Flats Environmental Technology Site (RFETS)-50,000 at RFETS and 170,000 at the Idaho National Engineering Laboratory. The cost of sampling the heterogeneous distribution of waste in each drum is prohibitive. In an attempt to produce a homogeneous mixture of waste that would reduce greatly the cost of sampling, researchers at NIST and RFETS are developing a cryogenic grinder. The Los Alamos work herein described addresses the implementation issues of the task. The first issue was to ascertain whether samples of the {open_quotes}small particle{close_quotes} mixtures of materials present in the waste drums at RFETS were representative of actual drum contents. Second, it was necessary to determine at what temperature the grinding operation must be performed in order to minimize or to eliminate the release of volatile organic compounds present in the waste. Last, it was essential to evaluate any effect the liquid cryogen might have on the structural integrity and ventilation capacity of the glovebox system. Results of this study showed that representative samples could be and had been obtained, that some release of organics occurred below freezing because of sublimation, and that operation of the cryogenic grinding equipment inside the glovebox was feasible.

  20. Time traces of individual kinesin motors suggest functional heterogeneity

    E-Print Network [OSTI]

    Reddy, Babu J N; Xu, Jing; Mattson, Michelle; Arabi, Karim; Vershinin, Michael; Gross, Steven; Hyeon, Changbong

    2015-01-01

    Conventional analysis of in vitro assays of motor proteins rests on the assumption that all proteins with the same chemical composition function identically; however molecule-to-molecule variation is often seen even in well-controlled experiments. In an effort to obtain a statistically meaningful set of time traces that simultaneously avoid any experimental artifacts, we performed quantum-dot labeled kinesin experiments on both surface and levitated microtubules. Similar to glassy systems, we found that mean velocities of individual kinesin motors vary widely from one motor to another, the variation of which is greater than that expected from the stochastic variation of stepping times. In the presence of heterogeneity, an ensemble-averaged quantity such as diffusion constant or randomness parameter is ill-defined. We propose to analyze heterogeneous data from single molecule measurements by decomposing them into homogeneous subensembles.

  1. Mathematics Education in Iceland: Explaining the Non-homogeneity in a Homogenous System

    E-Print Network [OSTI]

    Bardsley, John

    Mathematics Education in Iceland: Explaining the Non-homogeneity in a Homogenous System Guðný Helga Gunnarsdóttir, Guðbjörg Pálsdóttir University of Iceland, School of Education & Bharath Sriraman The University of Montana Abstract: In this opening salvo to the Icelandic section, we synthesize some

  2. 2012 Chinese Journal of Catalysis Vol. 33 No. 10 : 0253-9837(2012)10-1706-06 DOI: 10.3724/SP.J.1088.2012.20617 : 17061711

    E-Print Network [OSTI]

    Li, Weixue

    2012-01-01

    of Catalysis, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, Liaoning, China

  3. Microgrids and Heterogeneous Security, Quality, Reliability, andAvailability

    SciTech Connect (OSTI)

    Marnay, Chris

    2007-01-31

    This paper describes two stylized alternative visions inpopular currencyof how the power system might evolve to meet futurerequirements for the high quality electricity service that modern digitaleconomies demand, a supergrids paradigm and a dispersed paradigm. Some ofthe economics of the dispersed vision are explored. Economic perspectivesare presented on both the choice of homogeneous universal power qualityupstream in the electricity supply, and also on the extremelyheterogeneous require-ments of end-use loads. Finally, the potential roleof microgrids in delivering heterogeneous power quality is demonstratedby reference to two ongoing microgrid tests in the U.S. andJapan.

  4. Dynamical heterogeneities in an attraction driven colloidal glass

    E-Print Network [OSTI]

    Antonio M. Puertas; Matthias Fuchs; Michael E. Cates

    2006-01-16

    The dynamical heterogeneities (DH) in non-ergodic states of an attractive colloidal glass are studied, as a function of the waiting time. Whereas the fluid states close to vitrify showed strong DH, the distribution of squared displacements of the glassy states studied here only present a tail of particles with increased mobility for the lower attraction strength at short waiting times. These particles are in the surface of the percolating cluster that comprises all of the particles, reminiscent of the fastest particles in the fluid. The quench deeper into the attractive glass is dynamically more homogeneous, in agreement with repulsive glasses (i.e. Lennard-Jones glass).

  5. Characterization of the homogeneous tissue mixture approximation in breast imaging dosimetry

    SciTech Connect (OSTI)

    Sechopoulos, Ioannis; Bliznakova, Kristina; Qin Xulei; Fei Baowei; Feng, Steve Si Jia

    2012-08-15

    Purpose: To compare the estimate of normalized glandular dose in mammography and breast CT imaging obtained using the actual glandular tissue distribution in the breast to that obtained using the homogeneous tissue mixture approximation. Methods: Twenty volumetric images of patient breasts were acquired with a dedicated breast CT prototype system and the voxels in the breast CT images were automatically classified into skin, adipose, and glandular tissue. The breasts in the classified images underwent simulated mechanical compression to mimic the conditions present during mammographic acquisition. The compressed thickness for each breast was set to that achieved during each patient's last screening cranio-caudal (CC) acquisition. The volumetric glandular density of each breast was computed using both the compressed and uncompressed classified images, and additional images were created in which all voxels representing adipose and glandular tissue were replaced by a homogeneous mixture of these two tissues in a proportion corresponding to each breast's volumetric glandular density. All four breast images (compressed and uncompressed; heterogeneous and homogeneous tissue) were input into Monte Carlo simulations to estimate the normalized glandular dose during mammography (compressed breasts) and dedicated breast CT (uncompressed breasts). For the mammography simulations the x-ray spectra used was that used during each patient's last screening CC acquisition. For the breast CT simulations, two x-ray spectra were used, corresponding to the x-ray spectra with the lowest and highest energies currently being used in dedicated breast CT prototype systems under clinical investigation. The resulting normalized glandular dose for the heterogeneous and homogeneous versions of each breast for each modality was compared. Results: For mammography, the normalized glandular dose based on the homogeneous tissue approximation was, on average, 27% higher than that estimated using the true heterogeneous glandular tissue distribution (Wilcoxon Signed Rank Test p= 0.00046). For dedicated breast CT, the overestimation of normalized glandular dose was, on average, 8% (49 kVp spectrum, p= 0.00045) and 4% (80 kVp spectrum, p= 0.000089). Only two cases in mammography and two cases in dedicated breast CT with a tube voltage of 49 kVp resulted in lower dose estimates for the homogeneous tissue approximation compared to the heterogeneous tissue distribution. Conclusions: The normalized glandular dose based on the homogeneous tissue mixture approximation results in a significant overestimation of dose to the imaged breast. This overestimation impacts the use of dose estimates in absolute terms, such as for risk estimates, and may impact some comparative studies, such as when modalities or techniques with different x-ray energies are used. The error introduced by the homogeneous tissue mixture approximation in higher energy x-ray modalities, such as dedicated breast CT, although statistically significant, may not be of clinical concern. Further work is required to better characterize this overestimation and potentially develop new metrics or correction factors to better estimate the true glandular dose to breasts undergoing imaging with ionizing radiation.

  6. Conceptual design of a new homogeneous reactor for medical radioisotope Mo-99/Tc-99m production

    SciTech Connect (OSTI)

    Liem, Peng Hong [Nippon Advanced Information Service (NAIS Co., Inc.) Scientific Computational Division, 416 Muramatsu, Tokaimura, Ibaraki (Japan); Tran, Hoai Nam [Chalmers University of Technology, Dept. of Applied Physics, Div. of Nuclear Engineering, SE-412 96 Gothenburg (Sweden); Sembiring, Tagor Malem [National Nuclear Energy Agency (BATAN), Center for Reactor Technology and Nuclear Safety, Kawasan Puspiptek, Serpong, Tangerang Selatan, Banten (Indonesia); Arbie, Bakri [PT MOTAB Technology, Kedoya Elok Plaza Blok DA 12, Jl. Panjang, Kebun Jeruk, Jakarta Barat (Indonesia)

    2014-09-30

    To partly solve the global and regional shortages of Mo-99 supply, a conceptual design of a nitrate-fuel-solution based homogeneous reactor dedicated for Mo-99/Tc-99m medical radioisotope production is proposed. The modified LEU Cintichem process for Mo-99 extraction which has been licensed and demonstrated commercially for decades by BATAN is taken into account as a key design consideration. The design characteristics and main parameters are identified and the advantageous aspects are shown by comparing with the BATAN's existing Mo-99 supply chain which uses a heterogeneous reactor (RSG GAS multipurpose reactor)

  7. Homogenization of ferromagnetic materials by Franois Alouges

    E-Print Network [OSTI]

    Alouges, François

    the homogenzation theory for ferromagnetic materials. A new phenomenon arises, in particular to take into accountHomogenization of ferromagnetic materials by François Alouges Abstract In these notes we describe the geometric constraint that the magnetization is locally saturated. 1 Introduction Ferromagnetic materials

  8. Portable performance on heterogeneous architectures

    E-Print Network [OSTI]

    Phothilimthana, Phitchaya Mangpo

    Trends in both consumer and high performance computing are bringing not only more cores, but also increased heterogeneity among the computational resources within a single machine. In many machines, one of the greatest ...

  9. Catalysis of Electroweak Baryogenesis via Fermionic Higgs Portal Dark Matter

    E-Print Network [OSTI]

    Wei Chao; Michael J. Ramsey-Musolf

    2015-02-27

    We investigate catalysis of electroweak baryogenesis by fermionic Higgs portal dark matter using a two Higgs doublet model augmented by vector-like fermions. The lightest neutral fermion mass eigenstate provides a viable dark matter candidate in the presence of a stabilizing symmetry Z_2 or gauged U(1)_D symmetry. Allowing for a non-vanishing CP-violating phase in the lowest-dimension Higgs portal dark matter interactions allows generation of the observed dark matter relic density while evading direct detection bounds. The same phase provides a source for electroweak baryogenesis. We show that it is possible to obtain the observed abundances of visible and dark matter while satisfying present bounds from electric dipole moment (EDM) searches and direct detection experiments. Improving the present electron (neutron) EDM sensitivity by one (two) orders of magnitude would provide a conclusive test of this scenario.

  10. Highly efficient solid state catalysis by reconstructed (001) Ceria surface

    SciTech Connect (OSTI)

    Solovyov, VF; Ozaki, T; Atrei, A; Wu, LJ; Al-Mahboob, A; Sadowski, JT; Tong, X; Nykypanchuk, D; Li, Q

    2014-04-10

    Substrate engineering is a key factor in the synthesis of new complex materials. The substrate surface has to be conditioned in order to minimize the energy threshold for the formation of the desired phase or to enhance the catalytic activity of the substrate. The mechanism of the substrate activity, especially of technologically relevant oxide surfaces, is poorly understood. Here we design and synthesize several distinct and stable CeO2 (001) surface reconstructions which are used to grow epitaxial films of the high-temperature superconductor YBa2Cu3O7. The film grown on the substrate having the longest, fourfold period, reconstruction exhibits a twofold increase in performance over surfaces with shorter period reconstructions. This is explained by the crossover between the nucleation site dimensions and the period of the surface reconstruction. This result opens a new avenue for catalysis mediated solid state synthesis.

  11. Inverse magnetic catalysis in holographic models of QCD

    E-Print Network [OSTI]

    Kiminad A. Mamo

    2015-05-11

    We study the effect of magnetic field $B$ on the critical temperature $T_{c}$ of the confinement-deconfinement phase transition in hard-wall AdS/QCD, and holographic duals of flavored and unflavored $\\mathcal{N}=4$ super-Yang Mills theories on $\\mathbb{R}^3\\times \\rm S^1$. For all of the holographic models, we find that $T_{c}(B)$ decreases with increasing magnetic field $B\\ll T^2$, consistent with the inverse magnetic catalysis recently observed in lattice QCD for $B\\lesssim 1~GeV^2$. We also predict that, for large magnetic field $B\\gg T^2$, the critical temperature $T_{c}(B)$, eventually, starts to increase with increasing magnetic field $B\\gg T^2$ and asymptotes to a constant value.

  12. A New Equivalence Theory Method for Treating Doubly Heterogeneous Fuel - I. Theory

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Williams, Mark L.; Lee, Deokjung; Choi, Sooyoung

    2015-03-04

    A new methodology has been developed to treat resonance self-shielding in doubly heterogeneous very high temperature gas-cooled reactor systems in which the fuel compact region of a reactor lattice consists of small fuel grains dispersed in a graphite matrix. This new method first homogenizes the fuel grain and matrix materials using an analytically derived disadvantage factor from a two-region problem with equivalence theory and intermediate resonance method. This disadvantage factor accounts for spatial self-shielding effects inside each grain within the framework of an infinite array of grains. Then the homogenized fuel compact is self-shielded using a Bondarenko method to accountmore »for interactions between the fuel compact regions in the fuel lattice. In the final form of the equations for actual implementations, the double-heterogeneity effects are accounted for by simply using a modified definition of a background cross section, which includes geometry parameters and cross sections for both the grain and fuel compact regions. With the new method, the doubly heterogeneous resonance self-shielding effect can be treated easily even with legacy codes programmed only for a singly heterogeneous system by simple modifications in the background cross section for resonance integral interpolations. This paper presents a detailed derivation of the new method and a sensitivity study of double-heterogeneity parameters introduced during the derivation. The implementation of the method and verification results for various test cases are presented in the companion paper.« less

  13. A New Equivalence Theory Method for Treating Doubly Heterogeneous Fuel - I. Theory

    SciTech Connect (OSTI)

    Williams, Mark L.; Lee, Deokjung; Choi, Sooyoung

    2015-03-04

    A new methodology has been developed to treat resonance self-shielding in doubly heterogeneous very high temperature gas-cooled reactor systems in which the fuel compact region of a reactor lattice consists of small fuel grains dispersed in a graphite matrix. This new method first homogenizes the fuel grain and matrix materials using an analytically derived disadvantage factor from a two-region problem with equivalence theory and intermediate resonance method. This disadvantage factor accounts for spatial self-shielding effects inside each grain within the framework of an infinite array of grains. Then the homogenized fuel compact is self-shielded using a Bondarenko method to account for interactions between the fuel compact regions in the fuel lattice. In the final form of the equations for actual implementations, the double-heterogeneity effects are accounted for by simply using a modified definition of a background cross section, which includes geometry parameters and cross sections for both the grain and fuel compact regions. With the new method, the doubly heterogeneous resonance self-shielding effect can be treated easily even with legacy codes programmed only for a singly heterogeneous system by simple modifications in the background cross section for resonance integral interpolations. This paper presents a detailed derivation of the new method and a sensitivity study of double-heterogeneity parameters introduced during the derivation. The implementation of the method and verification results for various test cases are presented in the companion paper.

  14. Coherent State on SUq(2) Homogeneous Space

    E-Print Network [OSTI]

    N. Aizawa; R. Chakrabarti

    2009-06-30

    The generalized coherent states for quantum groups introduced by Jurco and Stovicek are studied for the simplest example SU_q(2) in full detail. It is shown that the normalized SU_q(2) coherent states enjoy the property of completeness, and allow a resolution of the unity. This feature is expected to play a key role in application of these coherent states in physical models. The homogeneous space of SU_q(2), i.e. the q-sphere of Podles, is reproduced in complex coordinates by using the coherent states. Differential calculus in the complex form on the homogeneous space is developed. High spin limit of the SU_q(2) coherent states is also discussed.

  15. Theoretical Investigation of Uranyl Dihydroxide: Oxo Ligand Exchange, Water Catalysis, and Vibrational Spectra

    E-Print Network [OSTI]

    Schlegel, H. Bernhard

    Theoretical Investigation of Uranyl Dihydroxide: Oxo Ligand Exchange, Water Catalysis is employed to investigate uranyl dihydroxide, UO2(OH)2, isomerization reaction energy barriers, including those occurring via proton shuttles. The ground-state structure of a uranyl dihydroxide complex

  16. Applied Catalysis A: General 243 (2003) 1524 On the potential role of hydroxyl groups in

    E-Print Network [OSTI]

    Marks, Laurence D.

    2003-01-01

    Applied Catalysis A: General 243 (2003) 15­24 On the potential role of hydroxyl groups in CO of metallic Au atoms and a cationic Au with a hydroxyl group. © 2002 Elsevier Science B.V. All rights reserved

  17. Catalysis Today 215 (2013) 3642 Contents lists available at SciVerse ScienceDirect

    E-Print Network [OSTI]

    Li, Weixue

    2013-01-01

    , Wei-Xue Li State Key Laboratory of Catalysis, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, China a r t i c l e i n f o Article history: Received 14 December 2012 Received

  18. Synergism of Catalysis and Reaction Center Rehybridization. An ab Initio Study of the

    E-Print Network [OSTI]

    Lewis, Michael

    were also obtained for the hydrolysis of SO3.18 Obviously, the catalysis arises in all of these cases/mol, and this result can be rationalized just as in the case of the other heterocumulenes and SO3

  19. Molecular computations for reactions and phase transitions: applications to protein stabilization, hydrates and catalysis

    E-Print Network [OSTI]

    Anderson, Brian J.

    In this work we have made significant contributions in three different areas of interest: therapeutic protein stabilization, thermodynamics of natural gas clathrate-hydrates, and zeolite catalysis. In all three fields, ...

  20. Studies of Immobilized Homogeneous Metal Catalysts on Silica Supports

    SciTech Connect (OSTI)

    Keith James Stanger

    2003-05-31

    The tethered, chiral, chelating diphosphine rhodium complex, which catalyzes the enantioselective hydrogenation of methyl-{alpha}-acetamidocinnamate (MAC), has the illustrated structure as established by {sup 31}P NMR and IR studies. Spectral and catalytic investigations also suggest that the mechanism of action of the tethered complex is the same as that of the untethered complex in solution. The rhodium complexes, [Rh(COD)H]{sub 4}, [Rh(COD){sub 2}]{sup +}BF{sub 4}{sup -}, [Rh(COD)Cl]{sub 2}, and RhCl{sub 3} {center_dot} 3H{sub 2}O, adsorbed on SiO{sub 2} are optimally activated for toluene hydrogenation by pretreatment with H{sub 2} at 200 C. The same complexes on Pd-SiO{sub 2} are equally active without pretreatments. The active species in all cases is rhodium metal. The catalysts were characterized by XPS, TEM, DRIFTS, and mercury poisoning experiments. Rhodium on silica catalyzes the hydrogenation of fluorobenzene to produce predominantly fluorocyclohexane in heptane and 1,2-dichloroethane solvents. In heptane/methanol and heptane/water solvents, hydrodefluorination to benzene and subsequent hydrogenation to cyclohexane occurs exclusively. Benzene inhibits the hydrodefluorination of fluorobenzene. In DCE or heptane solvents, fluorocyclohexane reacts with hydrogen fluoride to form cyclohexene. Reaction conditions can be chosen to selectively yield fluorocyclohexane, cyclohexene, benzene, or cyclohexane. The oxorhenium(V) dithiolate catalyst [-S(CH{sub 2}){sub 3}s-]Re(O)(Me)(PPh{sub 3}) was modified by linking it to a tether that could be attached to a silica support. Spectroscopic investigation and catalytic oxidation reactivity showed the heterogenized catalyst's structure and reactivity to be similar to its homogeneous analog. However, the immobilized catalyst offered additional advantages of recyclability, extended stability, and increased resistance to deactivation.

  1. Renewal-anomalous-heterogeneous files

    E-Print Network [OSTI]

    Ophir Flomenbom

    2010-08-13

    Renewal-anomalous-heterogeneous files are solved. A simple file is made of Brownian hard spheres that diffuse stochastically in an effective 1D channel. Generally, Brownian files are heterogeneous: the spheres' diffusion coefficients are distributed and the initial spheres' density is non-uniform. In renewal-anomalous files, the distribution of waiting times for individual jumps is exponential as in Brownian files, yet obeys: {\\psi}_{\\alpha} (t)~t^(-1-{\\alpha}), 0renewal as all the particles attempt to jump at the same time. It is shown that the mean square displacement (MSD) in a renewal-anomalous-heterogeneous file, , obeys, ~[_{nrml}]^{\\alpha}, where _{nrml} is the MSD in the corresponding Brownian file. This scaling is an outcome of an exact relation (derived here) connecting probability density functions of Brownian files and renewal-anomalous files. It is also shown that non-renewal-anomalous files are slower than the corresponding renewal ones.

  2. Nonuniversal Effects in the Homogeneous Bose Gas

    E-Print Network [OSTI]

    Eric Braaten; H. -W. Hammer; Shawn Hermans

    2000-12-04

    Effective field theory predicts that the leading nonuniversal effects in the homogeneous Bose gas arise from the effective range for S-wave scattering and from an effective three-body contact interaction. We calculate the leading nonuniversal contributions to the energy density and condensate fraction and compare the predictions with results from diffusion Monte Carlo calculations by Giorgini, Boronat, and Casulleras. We give a crude determination of the strength of the three-body contact interaction for various model potentials. Accurate determinations could be obtained from diffusion Monte Carlo calculations of the energy density with higher statistics.

  3. Pulsed Laser Powered Homogeneous Pyrolysis: A Computational Analysis

    E-Print Network [OSTI]

    Swihart, Mark T.

    Pulsed Laser Powered Homogeneous Pyrolysis: A Computational Analysis MARK T. SWIHART and ROBERT W pyrolysis technique for measuring unimolecular decomposition rate constants under unambiguously homogeneous. Introduction Pulsed laser powered homogeneous pyrolysis (LPHP) is a technique which may be used to measure

  4. Molecular-level Design of Heterogeneous Chiral Catalysts

    SciTech Connect (OSTI)

    Gellman, Andrew John; Sholl, David S.; Tysoe, Wilfred T.; Zaera, Francisco

    2013-04-28

    Understanding and controlling selectivity is one of the key challenges in heterogeneous catalysis. Among problems in catalytic selectivity enantioselectivity is perhaps the most the most challenging. The primary goal of the project on “Molecular-level Design of Heterogeneous Chiral Catalysts” is to understand the origins of enantioselectivity on chiral heterogeneous surfaces and catalysts. The efforts of the project team include preparation of chiral surfaces, characterization of chiral surfaces, experimental detection of enantioselectivity on such surfaces and computational modeling of the interactions of chiral probe molecules with chiral surfaces. Over the course of the project period the team of PI’s has made some of the most detailed and insightful studies of enantioselective chemistry on chiral surfaces. This includes the measurement of fundamental interactions and reaction mechanisms of chiral molecules on chiral surfaces and leads all the way to rationale design and synthesis of chiral surfaces and materials for enantioselective surface chemistry. The PI’s have designed and prepared new materials for enantioselective adsorption and catalysis. Naturally Chiral Surfaces • Completion of a systematic study of the enantiospecific desorption kinetics of R-3-methylcyclohexanone (R-3-MCHO) on 9 achiral and 7 enantiomeric pairs of chiral Cu surfaces with orientations that span the stereographic triangle. • Discovery of super-enantioselective tartaric acid (TA) and aspartic acid (Asp) decomposition as a result of a surface explosion mechanism on Cu(643)R&S. Systematic study of super-enantiospecific TA and Asp decomposition on five enantiomeric pairs of chiral Cu surfaces. • Initial observation of the enantiospecific desorption of R- and S-propylene oxide (PO) from Cu(100) imprinted with {3,1,17} facets by L-lysine adsorption. Templated Chiral Surfaces • Initial observation of the enantiospecific desorption of R- and S-PO from Pt(111) and Pd(111) modified by a variety of chiral templates. • Demonstrated enantioselective separation of racemic PO on chemically synthesized chiral gold nanoparticles. • Discovery of zwitterionic adsorption states of amino acids on Pd(111). • First structure determinations of adsorbed amino acids and identification of tetrameric chiral template structures. • Exploration of the enantiospecific interaction of PO and R-3-MCHO adsorption on chirally modified Cu(100), Cu(110) and Cu(111). One-to-One Interactions • Determination of cinchona orientation on Pt surfaces in situ at the solid-liquid interface using FT-IRAS. • Systematic study of the influence of solution properties on the adsorption of modified cinchonas alkaloids onto Pt surfaces. • Correlation of cinchona adsorption with catalytic activity, as affected by concentration, the nature of the solvent, and dissolved gases in the liquid phase. • Measurement of enantioselective chemisorption on 1-(1-naphthyl) ethylamine (NEA) modified Pt(111) and Pd(111) surfaces. • Imaging of chiral docking complexes between NEA and methyl pyruvate on Pd(111). Chiral Catalyst Synthesis • Anchoring of cinchona alkaloid to surfaces • Synthesis of chiral Au nanoparticles and demonstration of their enantiospecific interactions with R- and S-PO. • Elucidation of the driving forces for chiral imprinting of Cu(100) by L- and D-lysine to form Cu(3,1,17)R&S facets.

  5. Mesoscale harmonic analysis of homogenous dislocation nucleation

    E-Print Network [OSTI]

    Asad Hasan; Craig E. Maloney

    2012-05-08

    We perform atomistic computer simulations to study the mechanism of homogeneous dislocation nucleation in two dimensional (2D) hexagonal crystalline films during indentation with a circular nanoindenter. The nucleation process is governed by the vanishing of the energy associated with a single normal mode. This critical mode is largely confined to a single plane of adjacent atoms. For fixed film thickness, L, the spatial extent, \\xi, of the critical mode grows with indenter radius, R. For fixed R/L, the spatial extent \\xi, grows roughly as \\xi ~ L^0.4. We, furthermore, perform a mesoscale analysis to determine the lowest energy normal mode for mesoscale regions of varying radius, r_{meso}, centered on the critical mode's core. The energy, \\lambda_{meso}, of the lowest normal mode in the meso-region decays very rapidly with r_{meso} and \\lambda_{meso} ~= 0 for r_{meso} >~ \\xi. The lowest normal mode shows a spatial extent, \\xi_{meso}, which has a sublinear power-law increase with r_{meso} for r_{meso} mesoscale analysis gives good estimates for the energy and spatial extent of the critical mode \\emph{only} for r_{meso} >~ 1.5 \\xi. In this sense homogeneous dislocation nucleation should be understood as a quasi-local phenomenon.

  6. The Galaxy Distribution: Homogeneous, Fractal, or Neither

    E-Print Network [OSTI]

    J. L. McCauley

    2000-01-13

    From the standpoint of theoretical physics we can treat Newtonian cosmology as a problem in nonlinear dynamics. The attempt to average the density, in search of a method of making contact between theory and observation, is replaced by the more systematic idea of coarsegraining. I also explain in this context why two previous attempts at the construction of hierarchical models of the universe are not useful in data analysis. The main ideas behind two older competing data analyses purporting to show evidence from galaxy statistics for either a homogeneous and isotropic universe in one case, and for a mono-fractal universe in the other, are presented and discussed. I also present the method and results of a newer data analysis that shows that visible matter provides no evidence that would allow us to claim that the cosmological principle holds, or that the universe is fractal (or multifractal). In other words, observational data provides us with no evidence that the universe is either homogeneous and isotropic, or monofractal.

  7. Evidence for heterogeneity in facioscapulohumeral muscular dystrophy (FSHD)

    SciTech Connect (OSTI)

    Gilbert, J.R.; Stajich, J.M.; Wall, S.; Carter, S.C.; Qiu, H.; Vance, J.M.; Stewart, C.S.; Speer, M.C.; Pufky, J.; Yamaoka, L.H.; Rozear, M.; Roses, A.D.; Pericak-Vance, M.A. (Duke Univ. Medical Center, Durham, NC (United States)); Samson, F.; Fardeau, M. (INSERM, Paris (France))

    1993-08-01

    Facioscapulohumeral muscular dystrophy (FSHD) is a slowly progressive primary disease of muscle which is usually inherited as an autosomal dominant disorder. FSHD has been localized to the long arm of chromosome 4, specifically to the 4q3.5-qter region. Initially published linkage studies showed no evidence for heterogeneity in FSHD. In the present study the authors have examined individuals in seven FSHD families. Two-point lod scores show significant evidence for linkage for D4S163 (lod score 3.04 at recombination fraction .21) and D4S139 (lod score 3.84 at recombination fraction .20). D4S171 also gave a positive score (lod score 2.56 at recombination fraction .24). Significant evidence for heterogeneity was found for each of the three markers. Multipoint linkage analysis in this region resulted in a peak multipoint lod score of 6.47. The multipoint analysis supported the two-point studies with odds of 20:1 showing linkage and heterogeneity over linkage and homogeneity. Five of the seven families gave a posterior probability of >95% of being of the linked type, while two families appeared unlinked to this region of 4q (P<.01%). Individuals in the two unlinked families met the clinical criteria for the diagnosis of FSHD, including facial weakness, clavicular flattening, scapula winging, proximal muscle weakness, and myopathic changes on muscle biopsies without inflammatory or mitochondrial pathology. This study demonstrates genetic heterogeneity in FSHD and has important implications for both genetic counseling and the elucidation of the etiology of FSHD. 19 refs., 3 figs., 2 tabs.

  8. Variational Asymptotic Micromechanics Modeling of Heterogeneous Piezoelectric

    E-Print Network [OSTI]

    Yu, Wenbin

    piezoelectric materials are usually a better technical solution in the case of many applications such 1Variational Asymptotic Micromechanics Modeling of Heterogeneous Piezoelectric Materials Tian Tang properties and local fields of heterogeneous piezoelectric materials using the vari- ational asymptotic

  9. Organusulfur Catalysis With Reduced Molybdenum Sulfides Containing the Mo6S8 Cluster

    SciTech Connect (OSTI)

    Thomas Jay Paskach

    2002-08-27

    Industrial synthesis of sulfur-containing organic chemicals basically focuses on the broad categories of mercaptans (thiols), alkylsulfides (thioethers), polysulfides, and thiophenes. Of the organo-sulfur compounds produced, by far the most important in terms of quantities produced is methyl mercaptan (methanethiol or MeSH), which is produced mainly for the downstream production of methionine and methanesulfonyl chloride. Higher thiols are also used in the manufacture of rubber and plastics as polymerization regulators, chain transfer agents, or initiators. Other important organosulfur chemicals are dimethyl sulfide (DMS) and dimethyl disulfide (DMDS), both of which are used extensively for presulfiding of industrial hydroprocessing catalysts, and substituted thiophenes which are used as intermediates for production of agrochemicals, dyes, and pharmaceuticals. Thiols are produced commercially at the rate of about 10{sup 4} ton/yr from hydrogen sulfide (H{sub 2}S) and alcohols or olefins, using homogeneous free-radical synthesis, or heterogeneous catalysts based on solid acids or supported metal oxides and/or sulfides. Despite this large production rate, and the industrial importance of the organosulfur compounds, only limited research has been devoted to the development of new catalytic materials for their synthesis. Additionally, for most organosulfur catalytic reactions, only limited information exists about reaction mechanisms, active sites, adsorbed surface species, and especially the nature of the catalysts under reaction conditions.

  10. Homogeneous catalyst formulations for methanol production

    DOE Patents [OSTI]

    Mahajan, Devinder (Port Jefferson, NY); Sapienza, Richard S. (Shoreham, NY); Slegeir, William A. (Hampton Bays, NY); O'Hare, Thomas E. (Huntington Station, NY)

    1991-02-12

    There is disclosed synthesis of CH.sub.3 OH from carbon monoxide and hydrogen using an extremely active homogeneous catalyst for methanol synthesis directly from synthesis gas. The catalyst operates preferably between 100.degree.-150.degree. C. and preferably at 100-150 psia synthesis gas to produce methanol. Use can be made of syngas mixtures which contain considerable quantities of other gases, such as nitrogen, methane or excess hydrogen. The catalyst is composed of two components: (a) a transition metal carbonyl complex and (b) an alkoxide component. In the simplest formulation, component (a) is a complex of nickel tetracarbonyl and component (b) is methoxide (CH.sub.3 O.sup.-), both being dissolved in a methanol solvent system. The presence of a co-solvent such as p-dioxane, THF, polyalcohols, ethers, hydrocarbons, and crown ethers accelerates the methanol synthesis reaction.

  11. Homogeneous catalyst formulations for methanol production

    DOE Patents [OSTI]

    Mahajan, Devinder (Port Jefferson, NY); Sapienza, Richard S. (Shoreham, NY); Slegeir, William A. (Hampton Bays, NY); O'Hare, Thomas E. (Huntington Station, NY)

    1990-01-01

    There is disclosed synthesis of CH.sub.3 OH from carbon monoxide and hydrogen using an extremely active homogeneous catalyst for methanol synthesis directly from synthesis gas. The catalyst operates preferably between 100.degree.-150.degree. C. and preferably at 100-150 psia synthesis gas to produce methanol. Use can be made of syngas mixtures which contain considerable quantities of other gases, such as nitrogen, methane or excess hydrogen. The catalyst is composed of two components: (a) a transition metal carbonyl complex and (b) an alkoxide component. In the simplest formulation, component (a) is a complex of nickel tetracarbonyl and component (b) is methoxide (CH.sub.3 O.sup.13 ), both being dissolved in a methanol solvent system. The presence of a co-solvent such as p-dioxane, THF, polyalcohols, ethers, hydrocarbons, and crown ethers accelerates the methanol synthesis reaction.

  12. Memory Space Representation Heterogeneous Network Process Migration

    E-Print Network [OSTI]

    Sun, Xian-He

    Memory Space Representation for Heterogeneous Network Process Migration Kasidit Chanchio Xian@bit.csc.lsu.edu http://www.csc.lsu.edu/~scs/ Abstract A major difficulty of heterogeneous process migration is how and effective for heterogeneous network process migration. 1. Introduction As network computing becomes

  13. 2010 CATALYSIS GORDON RESEARCH CONFERENCE, JUNE 27 - JULY 2, 2010, NEW LONDON, NEW HAMPSHIRE

    SciTech Connect (OSTI)

    Abhaya Datye

    2010-07-02

    Catalysis is a key technology for improving the quality of life while simultaneously reducing the adverse impact of human activities on the environment. The discovery of new catalytic processes and the improvement of existing ones are also critically important for securing the nation's energy supply. The GRC on Catalysis is considered one the most prestigious conference for catalysis research, bringing together leading researchers from both academia, industry and national labs to discuss the latest, most exciting research in catalysis and the future directions for the field. The 2010 GRC on Catalysis will follow time-honored traditions and feature invited talks from the world's leading experts in the fundamentals and applications of catalytic science and technology. We plan to have increased participation from industry. The extended discussions in the company of outstanding thinkers will stimulate and foster new science. The conference will include talks in the following areas: Alternative feedstocks for chemicals and fuels, Imaging and spectroscopy, Design of novel catalysts, Catalyst preparation fundamentals, Molecular insights through theory, Surface Science, Catalyst stability and dynamics. In 2010, the Catalysis conference will move to a larger conference room with a new poster session area that will allow 40 posters per session. The dorm rooms provide single and double accommodations, free WiFi and the registration fee includes all meals and the famous lobster dinner on Thursday night. Afternoons are open to enjoy the New England ambiance with opportunities for hiking, sailing, golf and tennis to create an outstanding conference that will help you network with colleagues, and make long lasting connections.

  14. Growth mechanism of graphene on platinum: Surface catalysis and carbon segregation

    SciTech Connect (OSTI)

    Sun, Jie Lindvall, Niclas; Yurgens, August; Nam, Youngwoo; Cole, Matthew T.; Teo, Kenneth B. K.; Woo Park, Yung

    2014-04-14

    A model of the graphene growth mechanism of chemical vapor deposition on platinum is proposed and verified by experiments. Surface catalysis and carbon segregation occur, respectively, at high and low temperatures in the process, representing the so-called balance and segregation regimes. Catalysis leads to self-limiting formation of large area monolayer graphene, whereas segregation results in multilayers, which evidently “grow from below.” By controlling kinetic factors, dominantly monolayer graphene whose high quality has been confirmed by quantum Hall measurement can be deposited on platinum with hydrogen-rich environment, quench cooling, tiny but continuous methane flow and about 1000?°C growth temperature.

  15. Tropical Anvil Characteristics and Water Vapor of the Tropical Tropopause Layer (TTL): Impact of Homogeneous Freezing Parameterizations

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Homesum_a_epg0_fpd_mmcf_m.xls" ,"Available from WebQuantityBonneville Power AdministrationRobust,Field-effectWorking With U.S.WeekProducts[TRI-PARTYInnovationHeterogeneous and Homogeneous

  16. Homogenization of a locally-periodic medium with areas of low and high diffusivity

    E-Print Network [OSTI]

    van Noorden, T

    2010-01-01

    We aim at understanding transport in porous materials including regions with both high and low diffusivities. For such scenarios, the transport becomes structured (here: {\\em micro-macro}). The geometry we have in mind includes regions of low diffusivity arranged in a locally-periodic fashion. We choose a prototypical advection-diffusion system (of minimal size), discuss its formal homogenization (the heterogenous medium being now assumed to be made of zones with circular areas of low diffusivity of $x$-varying sizes), and prove the weak solvability of the limit two-scale reaction-diffusion model. A special feature of our analysis is that most of the basic estimates (positivity, $L^\\infty$-bounds, uniqueness, energy inequality) are obtained in $x$-dependent Bochner spaces.

  17. Homogeneous cosmology with aggressively expanding civilizations

    E-Print Network [OSTI]

    S. Jay Olson

    2014-11-17

    In the context of a homogeneous universe, we note that the appearance of aggressively expanding advanced life is geometrically similar to the process of nucleation and bubble growth in a first-order cosmological phase transition. We exploit this similarity to describe the dynamics of life saturating the universe on a cosmic scale, adapting the phase transition model to incorporate probability distributions of expansion and resource consumption strategies. Through a series of numerical solutions covering several orders of magnitude in the input assumption parameters, the resulting cosmological model is used to address basic questions related to the intergalactic spreading of life, dealing with issues such as timescales, observability, competition between strategies, and first-mover advantage. Finally, we examine physical effects on the universe itself, such as reheating and the backreaction on the evolution of the scale factor, if such life is able to control and convert a significant fraction of the available pressureless matter into radiation. We conclude that the existence of life, if certain advanced technologies are practical, could have a significant influence on the future large-scale evolution of the universe.

  18. Sandia Energy - Measurements of Thermal Stratification in a Homogenous...

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Measurements of Thermal Stratification in a Homogenous Charge Compression Ignition Engine Home Energy Transportation Energy CRF Facilities Partnership News News & Events Research &...

  19. Ion beam analyses of radionuclide migration in heterogeneous rocks

    SciTech Connect (OSTI)

    Alonso, Ursula; Missana, Tiziana; Garcia-Gutierrez, Miguel [CIEMAT, Avda. Complutense 40, Madrid 28040 (Spain); Patelli, Alessandro [CIVEN, Via delle Industrie 5, Venezia-Marghera 30175 (Italy); Rigato, Valentino; Ceccato, Daniele [LNL-INFN, Viale dell' Universita 2, Legnaro-Padova 35020 (Italy)

    2013-07-18

    The migration of radionuclides (RN) in the environment is a topic of general interest, for its implications on public health, and it is an issue for the long-term safety studies of deep geological repositories (DGR) for high-level radioactive waste. The role played by colloids on RN migration is also of great concern. Diffusion and sorption are fundamental mechanisms controlling RN migration in rocks and many experimental approaches are applied to determine transport parameters for low sorbing RN in homogeneous rocks. However, it is difficult to obtain relevant data for high sorbing RN or colloids, for which diffusion lengths are extremely short, or within heterogeneous rocks, where transport might be different in different minerals. The ion beam techniques Rutherford Backscattering Spectrometry (RBS) and micro-Particle Induced X-Ray Emission ({mu}PIXE), rarely applied in the field, were selected for their micro-analytical potential to study RN diffusion and surface retention within heterogeneous rocks. Main achievements obtained during last 12 years are highlighted.

  20. Journal of Catalysis 237 (2006) 111117 www.elsevier.com/locate/jcat

    E-Print Network [OSTI]

    Bell, Alexis T.

    2006-01-01

    , and the carboxylation of methane has been demonstrated in both water and strong acids using soluble V-based catalysts [4Journal of Catalysis 237 (2006) 111­117 www.elsevier.com/locate/jcat Methane oxidation to acetic Department of Chemical Engineering, University of California, Berkeley, CA 94720-1462, USA Received 13

  1. Applied Catalysis B: Environmental 37 (2002) 2735 NOx reduction by urea under lean conditions over

    E-Print Network [OSTI]

    Gulari, Erdogan

    2002-01-01

    Applied Catalysis B: Environmental 37 (2002) 27­35 NOx reduction by urea under lean conditions over using a single step sol­gel process (designated as 2% Pt-SG) and tested its activity for NOx reduction and hydrothermally stable in the range of 150­500 C in the reduction of NOx by hy- drocarbons or oxygenated

  2. A general approach to the enantioselective a-oxidation of aldehydes via synergistic catalysis

    E-Print Network [OSTI]

    MacMillan, David W. C.

    with Zhong, we reported the first catalytic enantioselective a-oxidation of aldehydes, utilizing nitroA general approach to the enantioselective a-oxidation of aldehydes via synergistic catalysis Scott 6th September 2011 DOI: 10.1039/c1sc00556a A new enantioselective a-oxidation of aldehydes has been

  3. Laboratory Evolution of Escherichia coli Thioredoxin for Enhanced Catalysis of Protein Oxidation in the Periplasm

    E-Print Network [OSTI]

    Bardwell, James

    catalytic activity in the oxidation of alkaline phosphatase but was unable to oxidize FlgI and restore cellLaboratory Evolution of Escherichia coli Thioredoxin for Enhanced Catalysis of Protein Oxidation, Michigan 48109 Thioredoxin exported into the Escherichia coli periplasm cat- alyzes the oxidation

  4. High surface area crystalline titanium dioxide: potential and limits in electrochemical energy storage and catalysis

    E-Print Network [OSTI]

    Pfeifer, Holger

    and it is widely applied, for example in photocatalysis, electrochemical energy storage, in white pigmentsHigh surface area crystalline titanium dioxide: potential and limits in electrochemical energy storage and catalysis T. Fröschl1 , U. Hörmann2 , P. Kubiak3 , G. Kucerova2 , M. Pfanzelt3 , C.K. Weiss4

  5. Challenges for the application of quantum chemical calculations to problems in catalysis

    E-Print Network [OSTI]

    Bell, Alexis T.

    2004) A long-standing goal of researchers in the field of catalysis is to develop first-principles of a catalysed reaction occurring in a reactor given knowledge only of reactor configuration, catalyst accurate determinations of reactor performance given a set of rate parameters describing catalyst

  6. Catalysis Today 165 (2011) 8995 Contents lists available at ScienceDirect

    E-Print Network [OSTI]

    Li, Weixue

    2011-01-01

    of Catalysis, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, China b Center for Computational and Theoretical Chemistry, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, China a r t i c l e i n f o Article history: Received 31 August 2010 Received in revised

  7. JOURNAL OF CATALYSIS 92, 127-135 (1985) Oxidative Dehydrogenation of Methanol to Formaldehyde'

    E-Print Network [OSTI]

    Goddard III, William A.

    1985-01-01

    JOURNAL OF CATALYSIS 92, 127-135 (1985) Oxidative Dehydrogenation of Methanol to Formaldehyde/mol at 275°C (I). Because of the extreme industrial impor- tance of formaldehyde for plastics, dyes, etc con- cepts are generally accepted regarding the oxidation of methanol to formaldehyde over Mo03: (a

  8. Catalysis Winter School 2012 Oxford University / Imperial College London / University College London

    E-Print Network [OSTI]

    Wallace, Mark

    . Simon Jones (Ox): Modified Palladium Nanoparticles for Hydrogen production from Formic acid 8. Thomas-borane (H3B.NMe2H) dehydrocoupling 2. Ed Emmett (Ox): Sulfonyl group incorporation using palladium catalysis and DABSO 3. Adam Healy (Ox): New insights into bio-catalytic hydrogen oxidation using electrochemistry

  9. HOMOGENEOUS 1-BASED STRUCTURES AND INTERPRETABILITY IN RANDOM STRUCTURES

    E-Print Network [OSTI]

    Djordjevic, Vera

    HOMOGENEOUS 1-BASED STRUCTURES AND INTERPRETABILITY IN RANDOM STRUCTURES VERA KOPONEN Abstract. Let -structure which is homogeneous, simple and 1- based. The rst main result says that if M is, in addition, primitive, then it is strongly interpretable in a random structure. The second main result, which

  10. Modelling long-distance seed dispersal in heterogeneous landscapes.

    SciTech Connect (OSTI)

    Levey, Douglas, J.; Tewlsbury, Joshua, J.; Bolker, Benjamin, M.

    2008-01-01

    1. Long-distance seed dispersal is difficult to measure, yet key to understanding plant population dynamics and community composition. 2. We used a spatially explicit model to predict the distribution of seeds dispersed long distances by birds into habitat patches of different shapes. All patches were the same type of habitat and size, but varied in shape. They occurred in eight experimental landscapes, each with five patches of four different shapes, 150 m apart in a matrix of mature forest. The model was parameterized with smallscale movement data collected from field observations of birds. In a previous study we validated the model by testing its predictions against observed patterns of seed dispersal in real landscapes with the same types and spatial configuration of patches as in the model. 3. Here we apply the model more broadly, examining how patch shape influences the probability of seed deposition by birds into patches, how dispersal kernels (distributions of dispersal distances) vary with patch shape and starting location, and how movement of seeds between patches is affected by patch shape. 4. The model predicts that patches with corridors or other narrow extensions receive higher numbers of seeds than patches without corridors or extensions. This pattern is explained by edgefollowing behaviour of birds. Dispersal distances are generally shorter in heterogeneous landscapes (containing patchy habitat) than in homogeneous landscapes, suggesting that patches divert the movement of seed dispersers, ‘holding’ them long enough to increase the probability of seed defecation in the patches. Dispersal kernels for seeds in homogeneous landscapes were smooth, whereas those in heterogenous landscapes were irregular. In both cases, long-distance (> 150 m) dispersal was surprisingly common, usually comprising approximately 50% of all dispersal events. 5. Synthesis . Landscape heterogeneity has a large influence on patterns of long-distance seed dispersal. Our results suggest that long-distance dispersal events can be predicted using spatially explicit modelling to scale-up local movements, placing them in a landscape context. Similar techniques are commonly used by landscape ecologists to model other types of movement; they offer much promise to the study of seed dispersal.

  11. Thermal concentrator homogenized with solar-shaped mantle

    E-Print Network [OSTI]

    Petiteau, David; Bellieud, Michel; Zerrad, Myriam; Amra, Claude

    2015-01-01

    We propose solar-shaped thermal concentrators designed with orthoradial layers and obtained in practice through the homogenization of an ideal thermal concentrator. Considering the spectral regime of the heat equation, we quantitatively evaluate at different pulsations the effectiveness of the homogenized concentrators by comparing the thermal flux existing in an ideal concentrator and the thermal flux in an homogenized concentrator. Dependence on the pulsation is shown to be negligible and plotting the effectiveness of the homogenized concentrators as a function of the number of orthoradial layers $N$, we determine the number of layers needed to achieve a certain effectiveness. Significantly high numbers $N$(ranging from a hundred to tens of thousands layers) are found highlighting the fact that achieving high effectiveness demands a high level of engineering of the homogenized concentrator.

  12. DEFLECTION OF A HETEROGENEOUS WIDE-BEAM UNDER UNIFORM PRESSURE LOAD

    SciTech Connect (OSTI)

    T. V. Holschuh; T. K. Howard; W. R. Marcum

    2014-07-01

    Oregon State University (OSU) and the Idaho National Laboratory (INL) are currently collaborating on a test program which entails hydro-mechanical testing of a generic plate type fuel element, or generic test plate assembly (GTPA), for the purpose of qualitatively demonstrating mechanical integrity of uranium-molybdenum monolithic plates as compared to that of uranium aluminum dispersion, and aluminum fuel plates onset by hydraulic forces. This test program supports ongoing work conducted for/by the Global Threat Reduction Initiative (GTRI) Fuels Development Program. This study’s focus supports the ongoing collaborative effort by detailing the derivation of an analytic solution for deflection of a heterogeneous plate under a uniform, distributed load in order to predict the deflection of test plates in the GTPA. The resulting analytical solutions for three specific boundary condition sets are then presented against several test cases of a homogeneous plate. In all test cases considered, the results for both homogeneous and heterogeneous plates are numerically identical to one another, demonstrating correct derivation of the heterogeneous solution. Two additional problems are presents herein that provide a representative deflection profile for the plates under consideration within the GTPA. Furthermore, qualitative observations are made about the influence of a more-rigid internal fuel-meat region and its influence on the overall deflection profile of a plate. Present work is being directed to experimentally confirm the analytical solution’s results using select materials.

  13. Solvation and Acid Strength Effects on Catalysis by Faujasite Zeolites

    SciTech Connect (OSTI)

    Gounder, Rajamani P.; Jones, Andrew J.; Carr, Robert T.; Iglesia, Enrique

    2012-02-01

    Kinetic, spectroscopic, and chemical titration data indicate that differences in monomolecular isobutane cracking and dehydrogenation and methanol dehydration turnover rates (per H+) among FAU zeolites treated thermally with steam (H-USY) and then chemically with ammonium hexafluorosilicate (CDHUSY) predominantly reflect differences in the size and solvating properties of their supercage voids rather than differences in acid strength. The number of protons on a given sample was measured consistently by titrations with Na+, with CH3 groups via reactions of dimethyl ether, and with 2,6-di-tert-butylpyridine during methanol dehydration catalysis; these titration values were also supported by commensurate changes in acidic OH infrared band areas upon exposure to titrant molecules. The number of protons, taken as the average of the three titration methods, was significantly smaller than the number of framework Al atoms (Alf) obtained from X-ray diffraction and 27Al magic angle spinning nuclear magnetic resonance spectroscopy on H-USY (0.35 H+/Alf) and CD-HUSY (0.69 H+/Alf). These data demonstrate that the ubiquitous use of Alf sites as structural proxies for active H+ sites in zeolites can be imprecise, apparently because distorted Al structures that are not associated with acidic protons are sometimes detected as Alf sites. Monomolecular isobutane cracking and dehydrogenation rate constants, normalized non-rigorously by the number of Alf species, decreased with increasing Na+ content on both H-USY and CD-HUSY samples and became undetectable at sub-stoichiometric exchange levels (0.32 and 0.72 Na+/Alf ratios, respectively), an unexpected finding attributed incorrectly in previous studies to the presence of minority ‘‘super-acidic’’ sites. These rate constants, when normalized rigorously by the number of residual H+ sites were independent of Na+ content on both H-USY and CD-HUSY samples, reflecting the stoichiometric replacement of protons that are uniform in reactivity by Na+ cations. Monomolecular isobutane cracking and dehydrogenation rate constants (per H+; 763 K), however, were higher on H-USY than CD-HUSY (by a factor of 1.4). Equilibrium constants for the formation of protonated methanol dimers via adsorption of gaseous methanol onto adsorbed methanol monomers, determined from kinetic studies of methanol dehydration to dimethyl ether (433 K), were also higher on H-USY than CD-HUSY (by a factor of 2.1). These larger constants predominantly reflect stronger dispersive interactions in H-USY, consistent with its smaller supercage voids that result from the occlusion of void space by extraframework Al (Alex) residues. These findings appear to clarify enduring controversies about the mechanistic interpretation of the effects of Na+ and Alex species on the catalytic reactivity of FAU zeolites. They also illustrate the need to normalize rates by the number of active sites instead of more convenient but less accurate structural proxies for such sites.

  14. The random Schrödinger equation: homogenization in time-dependent potentials

    E-Print Network [OSTI]

    Yu Gu; Lenya Ryzhik

    2015-06-08

    We analyze the solutions of the Schr\\"odinger equation with the low frequency initial data and a time-dependent weakly random potential. We prove a homogenization result for the low frequency component of the wave field. We also show that the dynamics generates a non-trivial energy in the high frequencies, which do not homogenize -- the high frequency component of the wave field remains random and the evolution of its energy is described by a kinetic equation. The transition from the homogenization of the low frequencies to the random limit of the high frequencies is illustrated by understanding the size of the small random fluctuations of the low frequency component.

  15. Hydrogen storage materials and method of making by dry homogenation

    DOE Patents [OSTI]

    Jensen, Craig M. (Kailua, HI); Zidan, Ragaiy A. (Honolulu, HI)

    2002-01-01

    Dry homogenized metal hydrides, in particular aluminum hydride compounds, as a material for reversible hydrogen storage is provided. The reversible hydrogen storage material comprises a dry homogenized material having transition metal catalytic sites on a metal aluminum hydride compound, or mixtures of metal aluminum hydride compounds. A method of making such reversible hydrogen storage materials by dry doping is also provided and comprises the steps of dry homogenizing metal hydrides by mechanical mixing, such as be crushing or ball milling a powder, of a metal aluminum hydride with a transition metal catalyst. In another aspect of the invention, a method of powering a vehicle apparatus with the reversible hydrogen storage material is provided.

  16. The roles of redox active cofactors in catalysis : structural studies of iron sulfur cluster and flavin dependent enzymes

    E-Print Network [OSTI]

    Goldman, Peter John

    2013-01-01

    Cofactors are highly prevalent in biological systems and have evolved to take on many functions in enzyme catalysis. Two cofactors, flavin adenine dinucleotide (FAD) and [4Fe-4S] clusters, were originally determined to aid ...

  17. Automatic Mapping of Real Time Radio Astronomy Signal Processing Pipelines onto Heterogeneous Clusters

    E-Print Network [OSTI]

    Filiba, Terry

    2013-01-01

    Astronomy Signal Processing Pipelines onto HeterogeneousAstronomy Signal Processing Pipelines onto HeterogeneousAstronomy Signal Processing Pipelines onto Heterogeneous

  18. Task and Machine Heterogeneities: Higher Moments Matter

    E-Print Network [OSTI]

    Maciejewski, Anthony A. "Tony"

    Task and Machine Heterogeneities: Higher Moments Matter Abdulla M. Al-Qawasmeh 1 , Anthony A.potter}@colostate.edu jtsmith@digitalglobe.com Abstract - One type of heterogeneous computing (HC) systems consists of machines in this matrix represents the ETC of a specific task on a specific machine when executed exclusively. Heuristics

  19. Geophysics of Chemical Heterogeneity in the Mantle

    E-Print Network [OSTI]

    Stixrude, Lars

    , transition zone Abstract Chemical heterogeneity, produced by the near-surface rock cycle and dom- inatedGeophysics of Chemical Heterogeneity in the Mantle Lars Stixrude and Carolina Lithgow. This lithologic-scale chemical het- erogeneity may survive in the mantle for as long as the age of Earth because

  20. Harmonic Morphisms from Homogeneous Spaces -Some Existence Theory -

    E-Print Network [OSTI]

    Gudmundsson, Sigmundur

    Harmonic Morphisms from Homogeneous Spaces - Some Existence Theory - Sigmundur Gudmundsson 2014 #12;Harmonic Morphisms Eigenfamilies - Constructions Orthogonal Harmonic Families - Constructions Low-Dimensional Classifications References Outline 1 Harmonic Morphisms Basics Geometric Motivation

  1. Molecular Dynamics Simulation of Homogeneous Crystal Nucleation in Polyethylene

    E-Print Network [OSTI]

    Yi, Peng

    Using a realistic united-atom force field, molecular dynamics simulations were performed to study homogeneous nucleation of the crystal phase at about 30% supercooling from the melts of n-pentacontahectane (C150) and a ...

  2. Tritium Technology Program TTP-1-3089 TPBAR Homogenized Composition

    SciTech Connect (OSTI)

    Love, Edward F.

    2014-10-12

    Homogenized TPBAR number densities contained herein have been derived for unclassified core physics calculations. The use of this information may not provide accurate, conservative or representative results and must be evaluated for applicability to the specific problem.

  3. Effect of high pressure homogenization on skim milk proteins 

    E-Print Network [OSTI]

    Liu, Yen-Hsiao

    1995-01-01

    standard with a known concentration. Homogenization inlet temperature significantly (P<.Ol) affected the percentage of the proteins in milk. The greatest changes in the distribution of proteins were observed between inlet temperatures of 40 and 75'C when...

  4. Fuel effects in homogeneous charge compression ignition (HCCI) engines

    E-Print Network [OSTI]

    Angelos, John P. (John Phillip)

    2009-01-01

    Homogenous-charge, compression-ignition (HCCI) combustion is a new method of burning fuel in internal combustion (IC) engines. In an HCCI engine, the fuel and air are premixed prior to combustion, like in a spark-ignition ...

  5. Testing homogeneity with the fossil record of galaxies

    E-Print Network [OSTI]

    Alan F. Heavens; Raul Jimenez; Roy Maartens

    2011-09-15

    The standard Friedmann model of cosmology is based on the Copernican Principle, i.e. the assumption of a homogeneous background on which structure forms via perturbations. Homogeneity underpins both general relativistic and modified gravity models and is central to the way in which we interpret observations of the CMB and the galaxy distribution. It is therefore important to probe homogeneity via observations. We describe a test based on the fossil record of distant galaxies: if we can reconstruct key intrinsic properties of galaxies as functions of proper time along their worldlines, we can compare such properties at the same proper time for our galaxy and others. We achieve this by computing the lookback time using radial Baryon Acoustic Oscillations, and the time along galaxy world line using stellar physics, allowing us to probe homogeneity, in principle anywhere inside the past light cone. Agreement in the results would be an important consistency test -- although it would not in itself prove homogeneity. Any significant deviation in the results however would signal a breakdown of homogeneity.

  6. On (no) inverse magnetic catalysis in the QCD hard and soft wall models

    E-Print Network [OSTI]

    Dudal, D; Mertens, T G

    2015-01-01

    In this paper, we study the influence of an external magnetic field in holographic QCD models where the backreaction is modeled in via an appropriate choice of the background metric. We add a phenomenological soft wall dilaton to incorporate better IR behavior (confinement). Elaborating on previous studies conducted by [JHEP 1505 (2015) 121], we first discuss the Hawking-Page transition, the dual of the deconfinement transition, as a function of the magnetic field. We confirm that the critical deconfinement temperature can drop with the magnetic field. Secondly, we study the quark condensate holographically as a function of the applied magnetic field and demonstrate that this model does not exhibit inverse magnetic catalysis at the level of the chiral transition. The quest for a holographic QCD model that qualitatively describes the inverse magnetic catalysis at finite temperature is thus still open. Throughout this work, we pay special attention to the different holographic parameters and we attempt to fix t...

  7. Kokes Awards for the 23rd North American Catalysis Society Meeting

    SciTech Connect (OSTI)

    Jacobs, Gary

    2014-01-31

    The Tri-State Catalysis Society awarded 107 Kokes Travel Awards. The program was very successful and to date this was the most Kokes Travel Awards ever awarded at a North American Catalysis Society Meeting. It provided students who merited an award the opportunity to attend the meeting, present a paper in the form of either an oral presentation or a poster presentation, and to serve the North American Catalysis Society by participating in the organization of the meeting. Students worked very hard during the week of the meeting to make it a success. Financial support for the Kokes awards was provided by DOE, NSF, NACS, as well as the Tri-State Catalysis Society, the latter through fund raising activities, and other donations. AT the meeting, each student received over $1050 in kind to offset the costs of registration fees ($260), hotel accommodations ($295.7), transportation ($400 travel allowance), as well as T-shirts ($20), and banquet tickets ($95 provided by donations from society members). In addition, for the first time, students received certificates that were signed by the President of NACS, Professor Enrique Iglesia, and by the Kokes Awards Chair, Gary Jacobs (see last page). A list of meeting co-chairs (i.e., Uschi M. Graham, Umit S. Ozkan, and Madan Bhassin) and the honorary chair (Burtron H. Davis) was also included on the certificate, along with the name of the recipient. The awardees were chosen on a merit-based guideline which also included the requirements of having a presentation accepted at the meeting and being a student at a North American University. The Richard J. Kokes Student Travel Award Committee (Gary Jacobs, Rodney Andrews, and Peter Smirniotis) with help from the Organizing Committee were able to secure money from four sources as detailed in Table 1. As detailed by our Treasurer, Dr. Helge Toufar of Clariant, the total amount spent was $105,000.

  8. Kokes Awards for the 22nd North American Catalysis Society Meeting, June 5-10, 2011

    SciTech Connect (OSTI)

    Fabio H. Ribeiro

    2011-06-05

    The biennial North American Catalysis Society (NACS) Meetings are the premiere conferences in the area of catalysis, surface science, and reaction engineering. The 22nd meeting will be held the week of June 5-10, 2011 in Detroit, Michigan. The objective of the Meetings is to bring together leading researchers for intensive scientific exchange and interactions. Financial support that offsets some of the associated costs (specifically, registration fee, airline tickets, and hotel accommodations) would encourage graduate students, and for the first time undergraduate students, to attend and participate meaningfully in this conference. The funds sought in this proposal will help support the Richard J. Kokes Travel Award program. Graduate students eligible for these merit-based Awards are those who study at a North American university and who will present at the Meeting. We have currently 209 applications and we expect to be able to fund about half of them. The NACS has traditionally sought to encourage graduate student, and this year for the first time undergraduate studies, participation at the National Meetings and providing financial support is the most effective means to do so. Their attendance would contribute significantly to their scientific training and communication and presentation skills. They would be exposed to the leading researchers from the US and abroad; they would meet their peers from other universities; they would learn about cutting-edge results that could benefit their research projects; and they may become interested in becoming active participants in the catalysis community. These young investigators represent the next generation of scientists and engineers, and their proper training will lead to future scientific breakthroughs and technological innovations that benefit the US economy. Advances in catalysis can come in the form of more energy-efficient and environmentally-friendly chemical processes, improved fuel cell performance, efficient hydrogen production, and a cleaner environment.

  9. Butadiene Complexes of Titanium(II) and Titanium(0): Synthesis, Butadiene Dimerization Catalysis, and Crystal

    E-Print Network [OSTI]

    Girolami, Gregory S.

    Butadiene Complexes of Titanium(II) and Titanium(0): Synthesis, Butadiene Dimerization Catalysis, where dmpe is 1,2-bis(dimethylphosphino)- ethane, reacts with 1,3-butadiene and trans,trans-1,4-diphenyl-1,3-butadiene at -20 °C to produce the titanium(II) butadiene complexes TiMe2(4-C4H4R2)(dmpe), where

  10. NMR Computational Studies of Solid Acidity/Fundamental Studies of Catalysis by Solid Acids

    SciTech Connect (OSTI)

    James F. Haw

    2008-06-28

    This project focused on catalysis by zeolites and the synergy of spectroscopic characterization and theoretical modeling. In collaboration with the Waroquier group in Belgium we used state-of-the-art quantum chemical simulations on a supramolecular model of both the HZSM-5 zeolite and the co-catalytic hydrocarbon pool species and calculated a full catalytic cycle (including all rate constants) for methanol-to-olefin (MTO) catalysis involving a hydrocarbon pool species. This work not only represents the most robust computational analysis of a successful MTO route to date, but it also succeeds in tying together the many experimental clues. That work was featured on the cover of Angewandte Chemie. More recently we elucidated several unsuspected roles for formaldehyde in methanol to olefin catalysis. Formaldehyde proves to be a key species responsible for both the growth of the catalytically active hydrocarbon pool and its inevitable aging into deactivated polycyclic aromatic species. The apparent inevitability of formaldehyde formation at high temperatures, in particular in contact with active metal or metal oxide surfaces, may put some fundamental limitations on the economic potential of conversion of methanol to olefins.

  11. Bedload sheets in heterogeneous sediment

    SciTech Connect (OSTI)

    Whiting, P.J.; Dietrich, W.E.; Leopold, L.B.; Drake, T.G.; Shreve, R.L.

    1988-02-01

    Field observations in streams with beds of coarse sand and fine gravel have revealed that bedload moves primarily as thin, migrating accumulations of sediment, and coarse grains cluster at their leading edge. These accumulations are one or two coarse grains high and are much longer (0.2-0.6 m long in sand; 0.5-2.0 m in fine gravel) than their height. The authors propose the term bedload sheet for these features, and the authors argue that they result from an instability inherent to bedload movement of moderately and poorly sorted sediment. In essence, coarse particles in the bedload slow or stop each other, trap finer particles in their interstices, and thus cause the coarse particles to become mobile again. Bedload sheets develop on the stoss side of dunes, causing the dune to advance incrementally with the arrival of each sheet. Successive deposition of coarse sediment from the leading edge followed by fine sediment may generate the grain-size sorting that distinguishes cross-bedding. Available flume experiments and field observations indicate that bedload sheets are a common, but generally unrecognized, feature of heterogeneous sediment transport.

  12. Linkage heterogeneity among 59 Dutch hereditary breast cancer families

    SciTech Connect (OSTI)

    Cornelis, R.S.; Vliet, M. van; Leeuwen, I. van

    1994-09-01

    We have investigated 59 Dutch kindreds with at least three first-degree relatives with breast and/or ovarian cancer for linkage to BRCA1 on 17q12-q21, using at least 4 microsatellite markers flanking BRCA1 on either side. Assuming no heterogeneity, the overall multipoint lod score in this group of families was -7.59. A marked clustering of lod scores >0.5 was observed among the 13 families with a mean age of onset lower than 45 (total lod score: +3.36). Among the 8 kindreds with a mean age of onset lower than 45 and {ge}3 cases diagnosed under 45, the lod score was +4.43. Interestingly, most of the evidence against linkage was found in 17 families with a mean age of onset between 45 and 54 (total lod score of -8.72). It was estimated that 28% of the breast-only families might be caused by BRCA1. Over the 16 breast-ovarian cancer families a lod score of -3.78 was obtained under homogeneity. The highest lod score was +0.57, assuming heterogeneity with 33% of the families being linked to BRCA1. One family gave a multipoint lod score of -2.01 and thereby satisfies the conventional criterion of an unlinked family. Our results support the conclusions from earlier work by others, namely that BRCA1 predisposes particularly to early-onset breast cancer. The proportion of breast-ovarian cancer families we found linked to BRCA1 is much lower than that found by the Breast Cancer Linkage Consortium. This might be caused by the single unlinked family against an insufficient number of families able to give conclusive positive lod scores.

  13. Scroll Waves Pinned to Moving Heterogeneities

    E-Print Network [OSTI]

    Hua Ke; Zhihui Zhang; Oliver Steinbock

    2014-12-04

    Three-dimensional excitable systems can selforganize vortex patterns that rotate around one-dimensional phase singularities called filaments. In experiments with the Belousov-Zhabotinsky reaction and numerical simulations, we pin these scroll waves to moving heterogeneities and demonstrate the controlled repositioning of their rotation centers. If the pinning site extends only along a portion of the filament, the phase singularity is stretched out along the trajectory of the heterogeneity which effectively writes the singularity into the system. Its trailing end point follows the heterogeneity with a lower velocity. This velocity, its dependence on the placement of the anchor, and the shape of the filament are explained by a curvature flow model.

  14. HYPERSONIC BUCKSHOT: ASTROPHYSICAL JETS AS HETEROGENEOUS COLLIMATED PLASMOIDS

    SciTech Connect (OSTI)

    Yirak, Kristopher; Frank, Adam; Cunningham, Andrew J.; Mitran, Sorin

    2009-04-20

    Herbig-Haro jets are commonly thought of as homogeneous beams of plasma traveling at hypersonic velocities. Structure within jet beams is often attributed to periodic or 'pulsed' variations of conditions at the jet source. Simulations based on this scenario result in knots extending across the jet diameter. Observations and recent high energy density laboratory experiments shed new light on structures below this scale and indicate they may be important for understanding the fundamentals of jet dynamics. In this paper, we offer an alternative to 'pulsed' models of protostellar jets. Using direct numerical simulations we explore the possibility that jets are chains of subradial clumps propagating through a moving interclump medium. Our models explore an idealization of this scenario by injecting small (r < r {sub jet}), dense ({rho}>{rho}{sub jet}) spheres embedded in an otherwise smooth interclump jet flow. The spheres are initialized with velocities differing from the jet velocity by {approx}15%. We find that the consequences of shifting from homogeneous to heterogeneous flows are significant as clumps interact with each other and with the interclump medium in a variety of ways. Structures which mimic what is expected from pulsed-jet models can form, as can be previously unseen, 'subradial' behaviors including backward facing bow shocks and off-axis working surfaces. While these small-scale structures have not been seen before in simulation studies, they are found in high-resolution jet observations. We discuss implications of our simulations for the interpretation of protostellar jets with regard to characterization of knots by a 'lifetime' or 'velocity history' approach as well as linking observed structures with central engines which produce the jets.

  15. Hypersonic Buckshot: Astrophysical Jets as Heterogeneous Collimated Plasmoids

    E-Print Network [OSTI]

    Kristopher Yirak; Adam Frank; Andrew J. Cunningham; Sorin Mitran

    2008-06-05

    Herbig-Haro (HH) jets are commonly thought of as homogeneous beams of plasma traveling at hypersonic velocities. Structure within jet beams is often attributed to periodic or ``pulsed'' variations of conditions at the jet source. Simulations based on this scenario result in knots extending across the jet diameter. Observations and recent high energy density laboratory experiments shed new light on structures below this scale and indicate they may be important for understanding the fundamentals of jet dynamics. In this paper we offer an alternative to ``pulsed'' models of protostellar jets. Using direct numerical simulations we explore the possibility that jets are chains of sub-radial clumps propagating through a moving inter-clump medium. Our models explore an idealization of this scenario by injecting small ($rjet}$), dense ($\\rho>\\rho_{jet}$) spheres embedded in an otherwise smooth inter-clump jet flow. The spheres are initialized with velocities differing from the jet velocity by $\\sim15$%. We find the consequences of shifting from homogeneous to heterogeneous flows are significant as clumps interact with each other and with the inter-clump medium in a variety of ways. Structures which mimic what is expected from pulsed-jet models can form, as can previously unseen ``sub-radial'' behaviors including backward facing bow shocks and off-axis working surfaces. While these small-scale structures have not been seen before in simulation studies, they are found in high resolution jet observations. We discuss implications of our simulations for the interpretation of protostellar jets with regard to characterization of knots by a ``lifetime'' or ``velocity history'' approach as well as linking observed structures with central engines which produce the jets.

  16. Catalysis Today 151 (2010) 3438 Contents lists available at ScienceDirect

    E-Print Network [OSTI]

    2010-01-01

    history: Available online 24 March 2010 Keywords: Zinc oxide Nanowires Photocatalysis Stearic acid a b rights reserved. 1. Introduction Heterogeneous photocatalysis on semiconductor surfaces has attracted

  17. Low-Temperature Hydrocarbon/CO Oxidation Catalysis in Support of HCCI Emission Control

    Broader source: Energy.gov [DOE]

    Development of catalyst materials to facilitate the low-temperature oxidation of hydrocarbons and CO in homogeneous charge compression ignition (HCCI) emissions.

  18. Homogeneous blue pattern: A rare presentation in an acral congenital melanocytic nevus

    E-Print Network [OSTI]

    2010-01-01

    Malvehy J. Homogeneous blue pattern in an acral congenitalof a plantar combined blue nevus: a simulator of melanoma.Homogeneous blue pattern: A rare presentation in an acral

  19. New Homogeneous Chromophore/Catalyst Concepts for the Solar-Driven...

    Office of Scientific and Technical Information (OSTI)

    Technical Report: New Homogeneous ChromophoreCatalyst Concepts for the Solar-Driven Reduction of Carbon Dioxide Citation Details In-Document Search Title: New Homogeneous...

  20. INFORMATION RESOURCES MANAGEMENT IN HETEROGENEOUS, DISTRIBUTED ENVIRONMENTS

    E-Print Network [OSTI]

    Hsu, Cheng

    for Manufacturing Productivity and Technology Transfer RENSSELAER POLYTECHNIC INSTITUTE Troy, NY 12180-3590 #12INFORMATION RESOURCES MANAGEMENT IN HETEROGENEOUS, DISTRIBUTED ENVIRONMENTS: A METADATABASE Conference on Computer Integrated Manufacturing, Rensselaer Polytechnic Institute, Troy, NY 12180, May 1990

  1. Reconciling Semantic Heterogeneity in Web Services Composition

    E-Print Network [OSTI]

    Li, Xitong

    Service Oriented Computing (SOC) is a popular computing paradigm for the development of distributed Web applications. Service composition, a key element of SOC, is severely hampered by various types of semantic heterogeneity ...

  2. Proximity Computations on Heterogeneous Computing Systems

    E-Print Network [OSTI]

    Work Optimization-based scheduling Automatically distribute dynamically generated jobs while heterogeneity) (With our optimization-based scheduling) #12;Current Work Results FPS +Tesla2075 +GTX480 +GTX580

  3. Characterizing aquifer heterogeneity using hydraulic tomography

    E-Print Network [OSTI]

    Wachter, Brian James

    2008-07-29

    Fine-scale heterogeneity in a geologic medium determines rates and directions of flow and of contaminant transport. Traditional methods of determining hydraulic conductivity provide only average values of hydraulic ...

  4. Heterogeneous Recycling in Fast Reactors

    SciTech Connect (OSTI)

    Forget, Benoit; Pope, Michael; Piet, Steven J.; Driscoll, Michael

    2012-07-30

    Current sodium fast reactor (SFR) designs have avoided the use of depleted uranium blankets over concerns of creating weapons grade plutonium. While reducing proliferation risks, this restrains the reactor design space considerably. This project will analyze various blanket and transmutation target configurations that could broaden the design space while still addressing the non-proliferation issues. The blanket designs will be assessed based on the transmutation efficiency of key minor actinide (MA) isotopes and also on mitigation of associated proliferation risks. This study will also evaluate SFR core performance under different scenarios in which depleted uranium blankets are modified to include minor actinides with or without moderators (e.g. BeO, MgO, B4C, and hydrides). This will be done in an effort to increase the sustainability of the reactor and increase its power density while still offering a proliferation resistant design with the capability of burning MA waste produced from light water reactors (LWRs). Researchers will also analyze the use of recycled (as opposed to depleted) uranium in the blankets. The various designs will compare MA transmutation efficiency, plutonium breeding characteristics, proliferation risk, shutdown margins and reactivity coefficients with a current reference sodium fast reactor design employing homogeneous recycling. The team will also evaluate the out-of-core accumulation and/or burn-down rates of MAs and plutonium isotopes on a cycle-by-cycle basis. This cycle-by-cycle information will be produced in a format readily usable by the fuel cycle systems analysis code, VISION, for assessment of the sustainability of the deployment scenarios.

  5. A Computationally Based Approach to Homogenizing Advanced Alloys

    SciTech Connect (OSTI)

    Jablonski, P D; Cowen, C J

    2011-02-27

    We have developed a computationally based approach to optimizing the homogenization heat treatment of complex alloys. The Scheil module within the Thermo-Calc software is used to predict the as-cast segregation present within alloys, and DICTRA (Diffusion Controlled TRAnsformations) is used to model the homogenization kinetics as a function of time, temperature and microstructural scale. We will discuss this approach as it is applied to both Ni based superalloys as well as the more complex (computationally) case of alloys that solidify with more than one matrix phase as a result of segregation. Such is the case typically observed in martensitic steels. With these alloys it is doubly important to homogenize them correctly, especially at the laboratory scale, since they are austenitic at high temperature and thus constituent elements will diffuse slowly. The computationally designed heat treatment and the subsequent verification real castings are presented.

  6. Variable valve timing in a homogenous charge compression ignition engine

    DOE Patents [OSTI]

    Lawrence, Keith E.; Faletti, James J.; Funke, Steven J.; Maloney, Ronald P.

    2004-08-03

    The present invention relates generally to the field of homogenous charge compression ignition engines, in which fuel is injected when the cylinder piston is relatively close to the bottom dead center position for its compression stroke. The fuel mixes with air in the cylinder during the compression stroke to create a relatively lean homogeneous mixture that preferably ignites when the piston is relatively close to the top dead center position. However, if the ignition event occurs either earlier or later than desired, lowered performance, engine misfire, or even engine damage, can result. The present invention utilizes internal exhaust gas recirculation and/or compression ratio control to control the timing of ignition events and combustion duration in homogeneous charge compression ignition engines. Thus, at least one electro-hydraulic assist actuator is provided that is capable of mechanically engaging at least one cam actuated intake and/or exhaust valve.

  7. Teleparallel Energy-Momentum Distribution of Spatially Homogeneous Rotating Spacetimes

    E-Print Network [OSTI]

    M. Sharif; M. Jamil Amir

    2007-12-08

    The energy-momentum distribution of spatially homogeneous rotating spacetimes in the context of teleparallel theory of gravity is investigated. For this purpose, we use the teleparallel version of Moller prescription. It is found that the components of energy-momentum density are finite and well-defined but are different from General Relativity. However, the energy-momentum density components become the same in both theories under certain assumptions. We also analyse these quantities for some special solutions of the spatially homogeneous rotating spacetimes.

  8. Multiscale Conformational Heterogeneity in Staphylococcal Protein A: Possible Determinant

    E-Print Network [OSTI]

    Richardson, David

    to conformational heterogeneity in crys- tal structures, from diverse crystal contacts to functionally rele- vant

  9. ComputerScience,TexasA&MUniversity Modeling Heterogeneous User

    E-Print Network [OSTI]

    Loguinov, Dmitri

    1 ComputerScience,TexasA&MUniversity Modeling Heterogeneous User Churn and Local Resilience of Unstructured P2P Networks Modeling Heterogeneous UserModeling Heterogeneous User Churn and Local Resilience ofChurn Churn and Local Resilience of Unstructured P2P Networks Modeling Heterogeneous User

  10. Classification of Message Spreading in a Heterogeneous Social Network

    E-Print Network [OSTI]

    Jendoubi, Siwar; Liétard, Ludovic; Yaghlane, Boutheina Ben

    2015-01-01

    Nowadays, social networks such as Twitter, Facebook and LinkedIn become increasingly popular. In fact, they introduced new habits, new ways of communication and they collect every day several information that have different sources. Most existing research works fo-cus on the analysis of homogeneous social networks, i.e. we have a single type of node and link in the network. However, in the real world, social networks offer several types of nodes and links. Hence, with a view to preserve as much information as possible, it is important to consider so-cial networks as heterogeneous and uncertain. The goal of our paper is to classify the social message based on its spreading in the network and the theory of belief functions. The proposed classifier interprets the spread of messages on the network, crossed paths and types of links. We tested our classifier on a real word network that we collected from Twitter, and our experiments show the performance of our belief classifier.

  11. Applied Catalysis A: General 378 (2010) 227233 Contents lists available at ScienceDirect

    E-Print Network [OSTI]

    2010-01-01

    Accepted 22 February 2010 Available online 1 March 2010 Keywords: Nanowires Photocatalysis Aqueous solution heterogeneous photocatalysis, which implies the use of an inert catalyst, non-hazardous oxidants and UV and/or visible light input. Heterogeneous photocatalysis is attracting extensive interest for the degradation

  12. Probing the Role of Metal Ions in RNA Catalysis: Kinetic and Thermodynamic Characterization of a Metal Ion Interaction with the 2-Moiety of the Guanosine

    E-Print Network [OSTI]

    Herschlag, Dan

    Probing the Role of Metal Ions in RNA Catalysis: Kinetic and Thermodynamic Characterization of a Metal Ion Interaction with the 2-Moiety of the Guanosine Nucleophile in the Tetrahymena Group I Ribozyme: Deciphering the role of individual metal ions in RNA catalysis is a tremendous challenge, as numerous metal

  13. CT-scan-monitored electrical-resistivity measurements show problems achieving homogeneous saturation

    SciTech Connect (OSTI)

    Sprunt, E.S.; Davis, R.M.; Muegge, E.L. (Mobil R and D Corp. (US)); Desai, K.P. (Saudi Aramco (SA))

    1991-06-01

    This paper reports on x-ray computerized tomography (CT) scans obtained during measurement of the electrical resistivity of core samples which revealed some problems in obtaining uniform saturation along the lengths of the samples. The electrical resistivity of core samples is measured as a function of water saturation to determine the saturation exponent used in electric-log interpretation. An assumption in such tests is that the water saturation is uniformly distributed. Failure of this assumption can result in errors in the determination of the saturation exponent. Three problems were identified in obtaining homogeneous water saturation in two samples of a Middle Eastern carbonate grainstone: a stationary front formed in one sample at 1-psi oil/brine capillary pressure, a moving front formed at oil/brine capillary pressure {le}4 psi in samples tested in fresh mixed-wettability and cleaned water-wet states, and the heterogeneous fluid distribution caused by a rapidly moving front did not dissipate when the capillary pressure was eliminated in the samples.

  14. Environment-based pin-power reconstruction method for homogeneous core calculations

    SciTech Connect (OSTI)

    Leroyer, H.; Brosselard, C.; Girardi, E.

    2012-07-01

    Core calculation schemes are usually based on a classical two-step approach associated with assembly and core calculations. During the first step, infinite lattice assemblies calculations relying on a fundamental mode approach are used to generate cross-sections libraries for PWRs core calculations. This fundamental mode hypothesis may be questioned when dealing with loading patterns involving several types of assemblies (UOX, MOX), burnable poisons, control rods and burn-up gradients. This paper proposes a calculation method able to take into account the heterogeneous environment of the assemblies when using homogeneous core calculations and an appropriate pin-power reconstruction. This methodology is applied to MOX assemblies, computed within an environment of UOX assemblies. The new environment-based pin-power reconstruction is then used on various clusters of 3x3 assemblies showing burn-up gradients and UOX/MOX interfaces, and compared to reference calculations performed with APOLLO-2. The results show that UOX/MOX interfaces are much better calculated with the environment-based calculation scheme when compared to the usual pin-power reconstruction method. The power peak is always better located and calculated with the environment-based pin-power reconstruction method on every cluster configuration studied. This study shows that taking into account the environment in transport calculations can significantly improve the pin-power reconstruction so far as it is consistent with the core loading pattern. (authors)

  15. GRADIENT THEORY FOR PLASTICITY VIA HOMOGENIZATION OF DISCRETE DISLOCATIONS

    E-Print Network [OSTI]

    Garroni, Adriana

    GRADIENT THEORY FOR PLASTICITY VIA HOMOGENIZATION OF DISCRETE DISLOCATIONS ADRIANA GARRONI theory for plasticity from a model of discrete dislocations. We restrict our analysis to the case of a cylindrical symmetry for the crystal in exam, so that the mathematical formulation will involve a two

  16. Modal Analysis of Homogeneous Optical Waveguides by Boundary Integral Method

    E-Print Network [OSTI]

    Modal Analysis of Homogeneous Optical Waveguides by Boundary Integral Method Lei Wang J. Allen Cox of the waveguide. Two dierent systems of boundary integral equations are derived for the numerical solutions of the discrete propagation constants; one of them is in the form of Fredholm integral equations of the second

  17. Homogenization of linear spatially periodic electronic Michel Lenczner

    E-Print Network [OSTI]

    Homogenization of linear spatially periodic electronic circuits Michel Lenczner January 20, 2006 Abstract: In this paper we establish a simplified model of general spatially periodic linear electronic is reported. 1 Introduction It is well known that when the size of an analog electronic network increases too

  18. Homogeneous Charge Compression Ignition: Formulation Effect of a Diesel Fuel

    E-Print Network [OSTI]

    Paris-Sud XI, Université de

    Homogeneous Charge Compression Ignition: Formulation Effect of a Diesel Fuel on the Initiation and the Combustion Potential of Olefin Impact in a Diesel Base Fuel D. Alseda1,2, X. Montagne1 and P. Dagaut2 1 -- Combustion en mode HCCI : impact de la formulation d'un carburant Diesel sur l'initiation et la combustion

  19. Lifetime Benefits through Load Balancing in Homogeneous Sensor Networks

    E-Print Network [OSTI]

    Haenggi, Martin

    , battery depletion is emulated so that it becomes possible to actually measure the load balancingLifetime Benefits through Load Balancing in Homogeneous Sensor Networks Daniele Puccinelli network. The use of load balancing schemes can be expected to provide significant lifetime benefits

  20. Liquidity-Sensitive Automated Market Makers via Homogeneous Risk Measures

    E-Print Network [OSTI]

    stream of research in au- tomated market making is the design of liquidity-sensitive automated marketLiquidity-Sensitive Automated Market Makers via Homogeneous Risk Measures Abraham Othman and Tuomas. Automated market makers are algorithmic agents that pro- vide liquidity in electronic markets. A recent

  1. Correlation between homogeneous propane pyrolysis and pyrocarbon deposition

    E-Print Network [OSTI]

    Boyer, Edmond

    Correlation between homogeneous propane pyrolysis and pyrocarbon deposition C´edric Descamps, G propane pyrolysis is studied in a 1-D hot-wall CVD furnace. The gas-phase pyrolysis is modelled in previous reports [6]: total pressure equal to 2 kPa, temperature between 900 K and 1400 K, and pure propane

  2. Combining Homogenization and Registration Jan Modersitzki and Stefan Wirtz

    E-Print Network [OSTI]

    Modersitzki, Jan

    . The homogenization, for example, might be treated based on morphological operations, illumination models, and/or statistical approaches (Markov random fields). For the regis- tration part, there exists a variety on the maintenance of grayvalues and hence none of these measures allow for a correction of grayvalues

  3. Emergence of spacetime from topologically homogeneous causal networks

    E-Print Network [OSTI]

    D'Ariano, Giacomo Mauro

    Emergence of space­time from topologically homogeneous causal networks Giacomo Mauro D'Ariano a Accepted 5 April 2013 Available online 29 May 2013 Keywords: Special relativity Space­time emergence Causal networks a b s t r a c t In this paper we study the emergence of Minkowski space­time from a discrete

  4. INVARIANT, INTRA-CLASS RETRIEVAL IN HOMOGENEOUS IMAGE DATABASES

    E-Print Network [OSTI]

    Wang, Yuan-Fang

    that can appear very similar to each other (what we call a "homogeneous" database, e.g., the FishBase containing thousands of fish images). The scheme comprises a global alignment and a local matching process. For example, scientific digital image libraries such as the FishBase [3] featuring thousands of images of fish

  5. Homogenized Maxwell's Equations; a Model for Varistor Ceramics

    E-Print Network [OSTI]

    Birnir, Björn

    Homogenized Maxwell's Equations; a Model for Varistor Ceramics Bj¨orn Birnir Niklas Wellander for a semiconducting ceramic material used in devices to pro- tect electrical equipment against overvoltages are associated with two types of failures in varistor ceramics. The upper bound corresponds two thermal heating

  6. Homogenized Maxwell's Equations; a Model for Varistor Ceramics

    E-Print Network [OSTI]

    Birnir, Björn

    Homogenized Maxwell's Equations; a Model for Varistor Ceramics BjË? orn Birnir Niklas Wellander for a semiconducting ceramic material used in devices to pro­ tect electrical equipment against overvoltages are associated with two types of failures in varistor ceramics. The upper bound corresponds two thermal heating

  7. The effect of temperature and homogenization pressure on enzymatic activity in cheese whey 

    E-Print Network [OSTI]

    Del Carmen, Maria Yanina

    1995-01-01

    Whey was homogenized by single and double stage homogenization at inlet temperatures of 12.8 and 35'C and at pressures up to 100 NTa. The proteolytic activity of the homogenized whey was determined by ninhydrin assay prior to homogenization...

  8. Catalysis Center for Energy Innovation (CCEI) | U.S. DOE Office of Science

    Office of Science (SC) Website

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Homesum_a_epg0_fpd_mmcf_m.xls" ,"Available from WebQuantityBonneville Power AdministrationRobust,Field-effectWorkingLosThe 26thIWalter H. Zinn, 1969CALCD Energy(SC)(SC) Catalysis

  9. Fe-porphyrin-based metal–organic framework films as high-surface concentration, heterogeneous catalysts for electrochemical reduction of CO2

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Hod, Idan; Sampson, Matthew D.; Deria, Pravas; Kubiak, Clifford P.; Farha, Omar K.; Hupp, Joseph T.

    2015-09-18

    Realization of heterogeneous electrochemical CO2-to-fuel conversion via molecular catalysis under high-flux conditions requires the assembly of large quantities of reactant-accessible catalysts on conductive surfaces. As a proof of principle, we demonstrate that electrophoretic deposition of thin films of an appropriately chosen metal–organic framework (MOF) material is an effective method for immobilizing the needed quantity of catalyst. For electrocatalytic CO2 reduction, we used a material that contains functionalized Fe-porphyrins as catalytically competent, redox-conductive linkers. The approach yields a high effective surface coverage of electrochemically addressable catalytic sites (~1015 sites/cm2). The chemical products of the reduction, obtained with ~100% Faradaic efficiency, aremore »mixtures of CO and H2. The results validate the strategy of using MOF chemistry to obtain porous, electrode-immobilized, networks of molecular catalysts having competency for energy-relevant electrochemical reactions.« less

  10. Heterogeneous catalysis and nanoscience are used to promote chemical transformations for energy production. These concepts are important in solid oxide fuel cells (SOFCs) which have the

    E-Print Network [OSTI]

    production. These concepts are important in solid oxide fuel cells (SOFCs) which have the potential in the Solid Oxide Fuel Cell Rio Cavendish Advisor: Peter Crozier October 17, 2012; 10:00 AM; ERC 490 School to provide an efficient and environmentally favorable power generation system. The SOFC is fuel

  11. Apparatus for unilateral generation of a homogeneous magnetic field

    DOE Patents [OSTI]

    Fukushima, E.; Rath, A.R.; Roeder, S.B.W.

    1984-05-01

    An apparatus for unilaterally producing a substantially homogeneous magnetic field. The apparatus includes two circular electromagnet coils, a small coil and a large coil, which are coaxial with one another and which are separated by a distance equal to one-half the difference in the radius of the two coils. By appropriate selection of electrical currents, which are passed through the coils in opposite directions, a region of homogeneous magnetic field is formed. This region is centered on the common axis of the two coils, at a point on the axis which is at a distance from the small coil equal to one-half the radius of the small coil, and which is on the opposite side of the small coil from the large coil. The apparatus has particular application in the field of diagnostic medical NMR and other NMR applications.

  12. Apparatus for unilateral generation of a homogeneous magnetic field

    DOE Patents [OSTI]

    Fukushima, Eiichi (Los Alamos, NM); Rath, Alan R. (San Diego, CA); Roeder, Stephen B. W. (La Mesa, CA)

    1988-01-01

    An apparatus for unilaterally producing a substantially homogeneous magnetic field. The apparatus includes two circular electromagnet coils, a small coil and a large coil, which are coaxial with one another and which are separated by a distance equal to one-half the difference in the radius of the two coils. By appropriate selection of electrical currents, which are passed through the coil in opposite directions, a region of homogeneous magnetic field is formed. This region is centered on the common axis of the two coils, at a point on the axis which is at a distance from the small coil equal to one-half the radius of the small coil, and which is on the opposite side of the small coil from the large coil. The apparatus has particular application in the field of diagnostic medical NMR and other NMR applications.

  13. Homogeneous charge engines -- Basis of cyclic variations. Final report

    SciTech Connect (OSTI)

    Whitelaw, J.H.

    1997-06-30

    The objectives of the Grant required investigations of cyclic variations in a homogeneous-charge engine initially with gas combustion and the air from ranging from near quiescent to the incorporation of swirl and tumble by valve inserts. Later experiments were performed with unleaded gasoline. The measurements included local velocity and cylinder pressure through the four strokes of a single-cylinder engine, under motored and firing conditions and with examination of the flame kernel growth by combinations of photography and flame-ionization gauges. In all cases, the measurements of in-cylinder characteristics were linked to performance as measured in terms of speed and its variability, load and emissions. The experiments progressed to consider deviations from homogeneous charge and included consideration of stratified charge with local injection of a rich mixture in the vicinity of the spark gap so as to establish a flame kernel which would propagate securely into an overall weak mixture.

  14. Centrifugal cosmological repulsive force in a homogeneous universe

    E-Print Network [OSTI]

    A. V. Klimenko; V. A. Klimenko

    2011-03-21

    We study the dynamics of homogeneous isotropic three-dimensional worlds filled with radiation (3R-worlds). It is shown that the dynamics of these worlds with the additional fourth large-scale spatial dimension leads to an important effect. At 3R-worlds the forces of repulsion appear. The source of these forces is the thermal energy of the radiation that fills these worlds. In the four-dimensional space, these forces are centrifugal. They operate in an external for 3R-world spatial dimension and stretch it. In the three-dimensional comoving coordinate system the centrifugal forces shows themselves as forces of repulsion. Standard Einstein's equations do not describe these forces. Written generalized Einstein's equation describing the dynamics of a homogeneous isotropic universe, taking into consideration the centrifugal forces of repulsion. We propose a cosmological model of the universe, based on these equations. This model apply to explain the observation data.

  15. Applied Catalysis A: General 467 (2013) 559567 Contents lists available at ScienceDirect

    E-Print Network [OSTI]

    2013-01-01

    Keywords: Aqueous solution growth Pulsed laser deposition Seed layer ZnO Nanowires Photocatalysis-hazardous oxidants and UV and/or visible light input. Heterogeneous photocatalysis is attracting extensive interest

  16. High load operation in a homogeneous charge compression ignition engine

    DOE Patents [OSTI]

    Duffy, Kevin P. (Metamora, IL); Kieser, Andrew J. (Morton, IL); Liechty, Michael P. (Chillicothe, IL); Hardy, William L. (Peoria, IL); Rodman, Anthony (Chillicothe, IL); Hergart, Carl-Anders (Peoria, IL)

    2008-12-23

    A homogeneous charge compression ignition engine is set up by first identifying combinations of compression ratio and exhaust gas percentages for each speed and load across the engines operating range. These identified ratios and exhaust gas percentages can then be converted into geometric compression ratio controller settings and exhaust gas recirculation rate controller settings that are mapped against speed and load, and made available to the electronic

  17. A Nth-order linear algorithm for extracting diffuse correlation spectroscopy blood flow indices in heterogeneous tissues

    SciTech Connect (OSTI)

    Shang, Yu; Yu, Guoqiang

    2014-09-29

    Conventional semi-infinite analytical solutions of correlation diffusion equation may lead to errors when calculating blood flow index (BFI) from diffuse correlation spectroscopy (DCS) measurements in tissues with irregular geometries. Very recently, we created an algorithm integrating a Nth-order linear model of autocorrelation function with the Monte Carlo simulation of photon migrations in homogenous tissues with arbitrary geometries for extraction of BFI (i.e., ?D{sub B}). The purpose of this study is to extend the capability of the Nth-order linear algorithm for extracting BFI in heterogeneous tissues with arbitrary geometries. The previous linear algorithm was modified to extract BFIs in different types of tissues simultaneously through utilizing DCS data at multiple source-detector separations. We compared the proposed linear algorithm with the semi-infinite homogenous solution in a computer model of adult head with heterogeneous tissue layers of scalp, skull, cerebrospinal fluid, and brain. To test the capability of the linear algorithm for extracting relative changes of cerebral blood flow (rCBF) in deep brain, we assigned ten levels of ?D{sub B} in the brain layer with a step decrement of 10% while maintaining ?D{sub B} values constant in other layers. Simulation results demonstrate the accuracy (errors?homogenous solution resulted in substantial errors in rCBF (34.5%???errors???60.2%) and BFIs in different layers. The Nth-order linear model simplifies data analysis, thus allowing for online data processing and displaying. Future study will test this linear algorithm in heterogeneous tissues with different levels of blood flow variations and noises.

  18. Dosimetry in Mammography: Average Glandular Dose Based on Homogeneous Phantom

    SciTech Connect (OSTI)

    Benevides, Luis A. [Naval Sea Systems Command,1333 Isaac Hull Avenue, Washington Navy Yard, DC 20376 (United States); Hintenlang, David E. [University of Florida, 202 Nuclear Sciences Center, P.O. Box 1183, Gainesville Florida 32611 (United States)

    2011-05-05

    The objective of this study was to demonstrate that a clinical dosimetry protocol that utilizes a dosimetric breast phantom series based on population anthropometric measurements can reliably predict the average glandular dose (AGD) imparted to the patient during a routine screening mammogram. AGD was calculated using entrance skin exposure and dose conversion factors based on fibroglandular content, compressed breast thickness, mammography unit parameters and modifying parameters for homogeneous phantom (phantom factor), compressed breast lateral dimensions (volume factor) and anatomical features (anatomical factor). The patient fibroglandular content was evaluated using a calibrated modified breast tissue equivalent homogeneous phantom series (BRTES-MOD) designed from anthropomorphic measurements of a screening mammography population and whose elemental composition was referenced to International Commission on Radiation Units and Measurements Report 44 and 46 tissues. The patient fibroglandular content, compressed breast thickness along with unit parameters and spectrum half-value layer were used to derive the currently used dose conversion factor (DgN). The study showed that the use of a homogeneous phantom, patient compressed breast lateral dimensions and patient anatomical features can affect AGD by as much as 12%, 3% and 1%, respectively. The protocol was found to be superior to existing methodologies. The clinical dosimetry protocol developed in this study can reliably predict the AGD imparted to an individual patient during a routine screening mammogram.

  19. Reducing the effects of acoustic heterogeneity with an iterative reconstruction method from experimental data in microwave induced thermoacoustic tomography

    SciTech Connect (OSTI)

    Wang, Jinguo; Zhao, Zhiqin Song, Jian; Chen, Guoping; Nie, Zaiping; Liu, Qing-Huo

    2015-05-15

    Purpose: An iterative reconstruction method has been previously reported by the authors of this paper. However, the iterative reconstruction method was demonstrated by solely using the numerical simulations. It is essential to apply the iterative reconstruction method to practice conditions. The objective of this work is to validate the capability of the iterative reconstruction method for reducing the effects of acoustic heterogeneity with the experimental data in microwave induced thermoacoustic tomography. Methods: Most existing reconstruction methods need to combine the ultrasonic measurement technology to quantitatively measure the velocity distribution of heterogeneity, which increases the system complexity. Different to existing reconstruction methods, the iterative reconstruction method combines time reversal mirror technique, fast marching method, and simultaneous algebraic reconstruction technique to iteratively estimate the velocity distribution of heterogeneous tissue by solely using the measured data. Then, the estimated velocity distribution is used subsequently to reconstruct the highly accurate image of microwave absorption distribution. Experiments that a target placed in an acoustic heterogeneous environment are performed to validate the iterative reconstruction method. Results: By using the estimated velocity distribution, the target in an acoustic heterogeneous environment can be reconstructed with better shape and higher image contrast than targets that are reconstructed with a homogeneous velocity distribution. Conclusions: The distortions caused by the acoustic heterogeneity can be efficiently corrected by utilizing the velocity distribution estimated by the iterative reconstruction method. The advantage of the iterative reconstruction method over the existing correction methods is that it is successful in improving the quality of the image of microwave absorption distribution without increasing the system complexity.

  20. Modeling the Energy Efficiency of Heterogeneous Clusters

    E-Print Network [OSTI]

    Teo, Yong-Meng

    are an alternative for energy-efficient clusters [18], [20], [23]. On the contrary, other researchersModeling the Energy Efficiency of Heterogeneous Clusters Lavanya Ramapantulu, Bogdan Marius Tudor analyze the energy efficiency of mixing high-performance and low-power nodes in a cluster. Using a model

  1. Vancouver: A Software Stack for Productive Heterogeneous

    E-Print Network [OSTI]

    .S. Department of Energy Vetter_Vancouver_SC10 Vancouver overview · Large-scale heterogeneous system deployments #12;3 Managed by UT-Battelle for the U.S. Department of Energy Vetter_Vancouver_SC10 Language tools optimizations #12;4 Managed by UT-Battelle for the U.S. Department of Energy Vetter_Vancouver_SC10 Runtime data

  2. Heterogeneous lithium niobate photonics on silicon substrates

    E-Print Network [OSTI]

    Fathpour, Sasan

    /waveguide on silicon," J. Lightwave Technol. 25(7), 1826­1831 (2007). 4. M. J. Weber, Handbook of Optical Materials and selective oxidation of refractory metals. The heterogeneous photonic platform is employed to demonstrate as a new electro-optic material," Nature 441(7090), 199­202 (2006). 7. K. K. Tsia, S. Fathpour, and B

  3. Systematically heterogeneous covariance in network gev models

    E-Print Network [OSTI]

    Bierlaire, Michel

    large in certain market seg- ments. The results also suggest that the two heterogeneous models with increasing computational power, but still requires substantial extra computational and memory resources and vector parameters respectively, and F is a transformational function with the properties that F (-) = 0

  4. Mapping mesoscale heterogeneity in the plastic deformation of a copper single crystal

    E-Print Network [OSTI]

    Magid, K. R.

    2009-01-01

    619. page 18 Mapping mesoscale heterogeneity in a deformedthese planes. page 36 Mapping mesoscale heterogeneity in aJanuary 2009, 77–107 Mapping mesoscale heterogeneity in the

  5. Design of a new reactor-like high temperature near ambient pressure scanning tunneling microscope for catalysis studies

    E-Print Network [OSTI]

    Tao, Franklin Feng; Nguyen, Luan; Zhang, Shiran

    2013-01-01

    Here, we present the design of a new reactor-like high-temperature near ambient pressure scanning tunneling microscope (HT-NAP-STM) for catalysis studies. This HT-NAP-STM was designed for exploration of structures of catalyst surfaces at atomic...

  6. Chloroyttrium 2(1-(Arylimino)alkyl)quinolin-8-olate Complexes: Synthesis, Characterization, and Catalysis of the Ring-Opening

    E-Print Network [OSTI]

    Glaser, Rainer

    the polymerization in the BnOH-free process. Most polymers generated by BnOH-assisted catalysis possess Mn values materials" because they are biocompatible, readily biodegradable, and easily recyclable. Because showed low catalytic activity and resulted in polymers with relatively low molecular weights.5 In sharp

  7. Structure of Human Epoxide Hydrolase Reveals Mechanistic Inferences on Bifunctional Catalysis in Epoxide and Phosphate Ester Hydrolysis,

    E-Print Network [OSTI]

    Hammock, Bruce D.

    is unclear. Recent experiments demonstrate that the N-terminal domain of human sEH catalyzes the metalStructure of Human Epoxide Hydrolase Reveals Mechanistic Inferences on Bifunctional Catalysis ReceiVed February 4, 2004 ABSTRACT: The X-ray crystal structure of human soluble epoxide hydrolase (s

  8. Channeling of Fusion Alpha-Particle Power Using Minority Ion Catalysis A. I. Zhmoginov and N. J. Fisch

    E-Print Network [OSTI]

    , with electrons kept cold, so that the effective fusion reactivity can be increased [9­11]. The meansChanneling of Fusion Alpha-Particle Power Using Minority Ion Catalysis A. I. Zhmoginov and N. J greatly facilitate controlled nuclear fusion. The parameter range for achieving this temperature disparity

  9. Reaction Kinetics and Catalysis Letters, Vol. 1, No. 2/1974/209-213 STOCHASTIC SIMULATION OF CHEMICAL REACTIONS BY

    E-Print Network [OSTI]

    Tóth, János

    OF CHEMICAL REACTIONS BY DIGITAL COMPUTER, H. APPLICATIONS T. Sipos1, J.TSth 2 and P. ~.rdi1 1. Danube Oil chemical reactions (especially those of biological interest, e.g. reactions exhibiting oscillationReaction Kinetics and Catalysis Letters, Vol. 1, No. 2/1974/209-213 STOCHASTIC SIMULATION

  10. Decarboxylative Arylation of Amino Acids via Photoredox Catalysis: A One-Step Conversion of Biomass to Drug

    E-Print Network [OSTI]

    MacMillan, David W. C.

    Decarboxylative Arylation of Amino Acids via Photoredox Catalysis: A One-Step Conversion of Biomass. This method offers rapid entry to prevalent benzylic amine architectures from an abundant biomass the worldwide abundance of biomass6 that incorporates carboxylate functionality (e.g., amino acids, -hydroxy

  11. Experimental investigation of supercritical CO2 trapping mechanisms at the Intermediate Laboratory Scale in well-defined heterogeneous porous media

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Trevisan, Luca; Pini, Ronny; Cihan, Abdullah; Birkholzer, Jens T.; Zhou, Quanlin; Illangasekare, Tissa H.

    2014-12-31

    The heterogeneous nature of typical sedimentary formations can play a major role in the propagation of the CO2 plume, eventually dampening the accumulation of mobile phase underneath the caprock. From core flooding experiments, it is also known that contrasts in capillary threshold pressure due to different pore size can affect the flow paths of the invading and displaced fluids and consequently influence the build- up of non-wetting phase (NWP) at interfaces between geological facies. The full characterization of the geologic variability at all relevant scales and the ability to make observations on the spatial and temporal distribution of the migrationmore »and trapping of supercritical CO2 is not feasible from a practical perspective. To provide insight into the impact of well-defined heterogeneous systems on the flow dynamics and trapping efficiency of supercritical CO2 under drainage and imbibition conditions, we present an experimental investigation at the meter scale conducted in synthetic sand reservoirs packed in a quasi-two-dimensional flow-cell. Two immiscible displacement experiments have been performed to observe the preferential entrapment of NWP in simple heterogeneous porous media. The experiments consisted of an injection, a fluid redistribution, and a forced imbibition stages conducted in an uncorrelated permeability field and a homogeneous base case scenario. We adopted x-ray attenuation analysis as a non-destructive technique that allows a precise measurement of phase saturations throughout the entire flow domain. By comparing a homogeneous and a heterogeneous scenario we have identified some important effects that can be attributed to capillary barriers, such as dampened plume advancement, higher non-wetting phase saturations, larger contact area between the injected and displaced phases, and a larger range of non-wetting phase saturations.« less

  12. Experimental Investigation of Supercritical CO2 Trapping Mechanisms at the Intermediate Laboratory Scale in Well-defined Heterogeneous Porous Media

    SciTech Connect (OSTI)

    Trevisan, Luca [Colorado School of Mines, Golden, CO (United States). Center for Experimental Study of Subsurface Environmental Processes (CESEP); Pini, Ronny [Colorado School of Mines, Golden, CO (United States). Petroleum Engineering Dept.; Cihan, Abdullah [Lawrence Berkeley National Lab., CA (United States); Birkholzer, Jens T. [Lawrence Berkeley National Lab., CA (United States); Zhou, Quanlin [Lawrence Berkeley National Lab., CA (United States); Illangasekare, Tissa H. [Colorado School of Mines, Golden, CO (United States). Center for Experimental Study of Subsurface Environmental Processes (CESEP)

    2014-01-01

    The heterogeneous nature of typical sedimentary formations can play a major role in the propagation of the CO2 plume, eventually dampening the accumulation of mobile phase underneath the caprock. From core flooding experiments, it is also known that contrasts in capillary threshold pressure due to different pore size can affect the flow paths of the invading and displaced fluids and consequently influence the build- up of non-wetting phase (NWP) at interfaces between geological facies. The full characterization of the geologic variability at all relevant scales and the ability to make observations on the spatial and temporal distribution of the migration and trapping of supercritical CO2 is not feasible from a practical perspective. To provide insight into the impact of well-defined heterogeneous systems on the flow dynamics and trapping efficiency of supercritical CO2 under drainage and imbibition conditions, we present an experimental investigation at the meter scale conducted in synthetic sand reservoirs packed in a quasi-two-dimensional flow-cell. Two immiscible displacement experiments have been performed to observe the preferential entrapment of NWP in simple heterogeneous porous media. The experiments consisted of an injection, a fluid redistribution, and a forced imbibition stages conducted in an uncorrelated permeability field and a homogeneous base case scenario. We adopted x-ray attenuation analysis as a non-destructive technique that allows a precise measurement of phase saturations throughout the entire flow domain. By comparing a homogeneous and a heterogeneous scenario we have identified some important effects that can be attributed to capillary barriers, such as dampened plume advancement, higher non-wetting phase saturations, larger contact area between the injected and displaced phases, and a larger range of non-wetting phase saturations.

  13. Spatial control in the heterogeneous nucleation of water

    E-Print Network [OSTI]

    Varanasi, Kripa K.

    Heterogeneous nucleation of water plays an important role in a wide range of natural and industrial processes. Though heterogeneous nucleation of water is ubiquitous and an everyday experience, spatial control of this ...

  14. STOCHASTIC DESIGN AND CONTROL IN RANDOM HETEROGENEOUS MATERIALS

    E-Print Network [OSTI]

    Del Moral , Pierre

    STOCHASTIC DESIGN AND CONTROL IN RANDOM HETEROGENEOUS MATERIALS RAPHAEL STERNFELS AND PHAEDON-STELIOS KOUTSOURELAKIS Abstract. The present paper discusses a sampling framework that enables the optimization concerned with problems relating to random heterogeneous materials where uncertainties arise from

  15. Change Management in Heterogeneous Semistructured Databases (Demonstration Description) \\Lambda

    E-Print Network [OSTI]

    Chawathe, Sudarshan S.

    Change Management in Heterogeneous Semistructured Databases (Demonstration Description) \\Lambda the trigger should fire. At Stanford we are addressing the problem of change management in heterogeneous TDIFF CORE QSS Tsimmis Figure 1: Components of our change management system subscribers of changes

  16. Semantic Taxonomy Induction from Heterogenous Evidence Computer Science Department

    E-Print Network [OSTI]

    Ng, Andrew Y.

    Semantic Taxonomy Induction from Heterogenous Evidence Rion Snow Computer Science Department­ tic taxonomies. Previous algorithms for taxonomy induction have typically focused on independent over heterogenous relationships to optimize the entire structure of the taxonomy, using knowl­ edge

  17. Semantic Taxonomy Induction from Heterogenous Evidence Computer Science Department

    E-Print Network [OSTI]

    Ng, Andrew Y.

    Semantic Taxonomy Induction from Heterogenous Evidence Rion Snow Computer Science Department- tic taxonomies. Previous algorithms for taxonomy induction have typically focused on independent over heterogenous relationships to optimize the entire structure of the taxonomy, using knowl- edge

  18. Virus transport in physically and geochemically heterogeneous subsurface porous media

    E-Print Network [OSTI]

    Ryan, Joe

    Virus transport in physically and geochemically heterogeneous subsurface porous media Subir for virus transport in physically and geochemically heterogeneous subsurface porous media is presented. The model involves solution of the advection­dispersion equation, which additionally considers virus

  19. Catalysis Workshop

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Homesum_a_epg0_fpd_mmcf_m.xls" ,"Available from WebQuantity ofkandz-cm11 OutreachProductswsicloudwsiclouddenDVA N C E D B LReports fromSheetsCascadia Analysis

  20. On the estimation of the electromagnetic, elastodynamic and piezoelectric properties of homogenized composite materials 

    E-Print Network [OSTI]

    Duncan, Andrew J.

    2009-01-01

    The work in this thesis concerns the estimation of the electromagnetic, elastodynamic and piezoelectric properties of homogenized composite materials (HCMs). A composite may be considered homogeneous if wavelengths are ...

  1. Controlling And Operating Homogeneous Charge Compression Ignition (Hcci) Engines

    DOE Patents [OSTI]

    Flowers, Daniel L. (San Leandro, CA)

    2005-08-02

    A Homogeneous Charge Compression Ignition (HCCI) engine system includes an engine that produces exhaust gas. A vaporization means vaporizes fuel for the engine an air induction means provides air for the engine. An exhaust gas recirculation means recirculates the exhaust gas. A blending means blends the vaporized fuel, the exhaust gas, and the air. An induction means inducts the blended vaporized fuel, exhaust gas, and air into the engine. A control means controls the blending of the vaporized fuel, the exhaust gas, and the air and for controls the inducting the blended vaporized fuel, exhaust gas, and air into the engine.

  2. Periodic homogenization and material symmetry in linear elasticity

    E-Print Network [OSTI]

    Mariya Ptashnyk; Brian Seguin

    2015-05-07

    Here homogenization theory is used to establish a connection between the symmetries of a periodic elastic structure associated with the microscopic properties of an elastic material and the material symmetries of the effective, macroscopic elasticity tensor. Previous results of this type exist but here more general symmetries on the microscale are considered. Using an explicit example, we show that it is possible for a material to be fully anisotropic on the microscale and yet have a nontrivial material symmetry group on the macroscale. Another example demonstrates that not all material symmetries of the macroscopic elastic tensor are generated by symmetries of the periodic elastic structure.

  3. Exhaust gas recirculation in a homogeneous charge compression ignition engine

    DOE Patents [OSTI]

    Duffy, Kevin P. (Metamora, IL); Kieser, Andrew J. (Morton, IL); Rodman, Anthony (Chillicothe, IL); Liechty, Michael P. (Chillicothe, IL); Hergart, Carl-Anders (Peoria, IL); Hardy, William L. (Peoria, IL)

    2008-05-27

    A homogeneous charge compression ignition engine operates by injecting liquid fuel directly in a combustion chamber, and mixing the fuel with recirculated exhaust and fresh air through an auto ignition condition of the fuel. The engine includes at least one turbocharger for extracting energy from the engine exhaust and using that energy to boost intake pressure of recirculated exhaust gas and fresh air. Elevated proportions of exhaust gas recirculated to the engine are attained by throttling the fresh air inlet supply. These elevated exhaust gas recirculation rates allow the HCCI engine to be operated at higher speeds and loads rendering the HCCI engine a more viable alternative to a conventional diesel engine.

  4. Zebrafish collective behaviour in heterogeneous environment modeled by a stochastic model based on visual perception

    E-Print Network [OSTI]

    Collignon, Bertrand; Halloy, José

    2015-01-01

    Collective motion is one of the most ubiquitous behaviours displayed by social organisms and has led to the development of numerous models. Recent advances in the understanding of sensory system and information processing by animals impel to revise classical assumptions made in decisional algorithms. In this context, we present a new model describing the three dimensional visual sensory system of fish that adjust their trajectory according to their perception field. Furthermore, we introduce a new stochastic process based on a probability distribution function to move in targeted directions rather than on a summation of influential vectors as it is classically assumed by most models. We show that this model can spontaneously transits from consensus to choice. In parallel, we present experimental results of zebrafish (alone or in group of 10) swimming in both homogeneous and heterogeneous environments. We use these experimental data to set the parameter values of our model and show that this perception-based a...

  5. Weak law of large numbers for some Markov chains along non homogeneous genealogies

    E-Print Network [OSTI]

    Paris-Sud XI, Université de

    Weak law of large numbers for some Markov chains along non homogeneous genealogies Vincent Bansaye goes to infinity. It is described by a discrete genealogy which may be time non-homogeneous and we pay of the trait of each individual along this genealogy and may also be time non- homogeneous. Such models

  6. Efficient Implementation Algorithm for a Homogenized Energy Model with Thermal Relaxation

    E-Print Network [OSTI]

    Efficient Implementation Algorithm for a Homogenized Energy Model with Thermal Relaxation Thomas R to implement the homogenized energy hysteresis model with thermal relaxation for both ferroelectric For Algorithm 1. Algorithm used to implement the homogenized energy model with negligible thermal relaxation

  7. Microstructure and nonlinear signatures of yielding in a heterogeneous colloidal gel under large amplitude oscillatory shear

    SciTech Connect (OSTI)

    Kim, Juntae; Helgeson, Matthew E.; Merger, Dimitri; Wilhelm, Manfred

    2014-09-01

    We investigate yielding in a colloidal gel that forms a heterogeneous structure, consisting of a two-phase bicontinuous network of colloid-rich domains of fractal clusters and colloid-poor domains. Combining large amplitude oscillatory shear measurements with simultaneous small and ultra-small angle neutron scattering (rheo-SANS/USANS), we characterize both the nonlinear mechanical processes and strain amplitude-dependent microstructure underlying yielding. We observe a broad, three-stage yielding process that evolves over an order of magnitude in strain amplitude between the onset of nonlinearity and flow. Analyzing the intracycle response as a sequence of physical processes reveals a transition from elastic straining to elastoplastic thinning (which dominates in region I) and eventually yielding (which evolves through region II) and flow (which saturates in region III), and allows quantification of instantaneous nonlinear parameters associated with yielding. These measures exhibit significant strain rate amplitude dependence above a characteristic frequency, which we argue is governed by poroelastic effects. Correlating these results with time-averaged rheo-USANS measurements reveals that the material passes through a cascade of structural breakdown from large to progressively smaller length scales. In region I, compression of the fractal domains leads to the formation of large voids. In regions II and III, cluster-cluster correlations become increasingly homogeneous, suggesting breakage and eventually depercolation of intercluster bonds at the yield point. All significant structural changes occur on the micron-scale, suggesting that large-scale rearrangements of hundreds or thousands of particles, rather than the homogeneous rearrangement of particle-particle bonds, dominate the initial yielding of heterogeneous colloidal gels.

  8. Chemical Homogeneity in Collinder 261 and Implications for Chemical Tagging

    E-Print Network [OSTI]

    G. M. De Silva; K. C. Freeman; M. Asplund; J. Bland-Hawthorn; M. S. Bessell; R. Collet

    2006-11-28

    This paper presents abundances for 12 red giants of the old open cluster Collinder 261 based on spectra from VLT/UVES. Abundances were derived for Na, Mg, Si, Ca, Mn, Fe, Ni, Zr and Ba. We find the cluster has a solar-level metallicity of [Fe/H] = -0.03 dex. However some alpha elements were found to be enhanced. The star-to-star scatter was consistent with the expected measurement uncertainty for all elements. The observed rms scatter is as follows: Na = 0.07, Mg = 0.05, Si = 0.06, Ca = 0.05, Mn = 0.03, Fe = 0.02, Ni = 0.04, Zr = 0.12, and Ba = 0.03 dex. The intrinsic scatter was estimated to be less than 0.05 dex. Such high levels of homogeneity indicate that chemical information remains preserved in this old open cluster. We use the chemical homogeneity we have now established in Cr 261, Hyades and the HR1614 moving group to examine the uniqueness of the individual cluster abundance patterns, ie. chemical signatures. We demonstrate that the three studied clusters have unique chemical signatures, and discuss how other such signatures may be searched for in the future. Our findings support the prospect of chemically tagging disk stars to common formation sites in order to unravel the dissipative history of the Galactic disk.

  9. Final Report: Experimental and Theoretical Studies of Surface Oxametallacycles - Connections to Heterogeneous Olefin Epoxidation

    SciTech Connect (OSTI)

    Mark A. Barteau

    2009-09-15

    This project has aimed at the rational design of catalysts for direct epoxidation of olefins. This chemistry remains one of the most challenging problems in heterogeneous catalysis. Although the epoxidation of ethylene by silver catalysts to form ethylene oxide (EO) has been practiced for decades, little progress has been made in expanding this technology to other products and processes. We have made significant advances through the combination of surface science experiments, Density Functional Theory (DFT) calculations, and catalytic reactor experiments, toward understanding the mechanism of this reaction on silver catalysts, and to the rational improvement of selectivity. The key has been our demonstration of surface oxametallacycle intermediates as the species that control reaction selectivity. This discovery permits the influence of catalyst promoters on selectivity to be probed, and new catalyst formulations to be developed. It also guides the development of new chemistry with potential for direct epoxidation of more complex olefins. During the award period we have focused on 1. the formation and reaction selectivity of complex olefin epoxides on silver surfaces, and 2. the influence of co-adsorbed oxygen atoms on the reactions of surface oxametallacycles on silver, and 3. the computational prediction, synthesis, characterization and experimental evaluation of bimetallic catalysts for ethylene epoxidation. The significance of these research thrusts is as follows. Selective epoxidation of olefins more complex than ethylene requires suppression of not only side reactions available to the olefin such as C-H bond breaking, but it requires formation and selective ring closure of the corresponding oxametallacycle intermediates. The work carried out under this grant has significantly advanced the field of catalyst design from first principles. The combination of computational tools, surface science, and catalytic reactor experiments in a single laboratory has few other examples. We have successfully predicted and validated new bimetallic catalyst for ethylene epoxidation. In so doing, we have established one of the first examples of successful catalyst design from first principles to achieve improved reaction selectivity.

  10. Effect of high pressure homogenization on lactic acid starter culture and the accelerated ripening of Cheddar cheese 

    E-Print Network [OSTI]

    Gonzalez Ortiz, Monica Lizeth

    1998-01-01

    48 hours for 10 days. Homogenization increased endopeptidase, general aminopeptidase, and aminopeptidase A activity of the homogenized culture with greatest activity observed after homogenization at 90 MPa and nine cycles. Acid production was lowest...

  11. Heterogeneous ice nucleation and water uptake by field-collected atmospheric particles below 273 K

    SciTech Connect (OSTI)

    Wang, Bingbing; Laskin, Alexander; Roedel, Tobias R.; Gilles, Marry K.; Moffet, Ryan C.; Tivanski, Alexei V.; Knopf, Daniel A.

    2012-09-25

    Atmospheric ice formation induced by particles with complex chemical and physical properties through heterogeneous nucleation is not well understood. Heterogeneous ice nucleation and water uptake by ambient particles collected from urban environments in Los Angeles and Mexico City are presented. Using a vapour controlled cooling system equipped with an optical microscopy, the range of onset conditions for ice nucleation and water uptake by the collected particles was determined as a function of temperature (200{273 K) and relative humidity with respect to ice (RHice) up to water saturation. Three distinctly different types of authentic atmospheric particles were investigated including soot particles associated with organics/inorganics, inorganic particles of marine origin coated with organic material, and Pb/Zn containing inorganic particles apportioned to anthropogenic emissions relevant to waste incineration. Single particle characterization was provided by micro-spectroscopic analyses using computer controlled scanning electron microscopy with energy dispersive analysis of X-rays (CCSEM/EDX) and scanning transmission X-ray microscopy with near edge X-ray absorption ne structure spectroscopy (STXM/NEXAFS). Above 230 K, signicant differences in water uptake and immersion freezing effciencies of the different particle types were observed. Below 230 K, the particles exhibited high deposition ice nucleation effciencies and formed ice at RHice values well below homogeneous ice nucleation limits. The data show that the chemical composition of these eld{collected particles plays an important role in determining water uptake and immersion freezing. Heterogeneous ice nucleation rate coeffcients, cumulative ice nuclei (IN) spectrum, and IN activated fraction for deposition ice nucleation are derived. The presented ice nucleation data demonstrate that anthropogenic and marine particles comprising of various chemical and physical properties exhibit distinctly different ice nucleation effciencies and can serve as effcient IN at atmospheric conditions typical for cirrus and mixed phase clouds. This indicates a potential link between human activities and cloud formation, and thus climate.

  12. Renewal convergence rates and correlation decay for homogeneous pinning models

    E-Print Network [OSTI]

    Giambattista Giacomin

    2007-06-03

    A class of discrete renewal processes with super-exponentially decaying inter-arrival distributions coincides with the infinite volume limit of general homogeneous pinning models in their localized phase. Pinning models are statistical mechanics systems to which a lot of attention has been devoted both for their relevance for applications and because they are solvable models exhibiting a non-trivial phase transition. The spatial decay of correlations in these systems is directly mapped to the speed of convergence to equilibrium for the associated renewal processes. We show that close to criticality, under general assumptions, the correlation decay rate, or the renewal convergence rate, coincides with the inter-arrival decay rate. We also show that, in general, this is false away from criticality. Under a stronger assumption on the inter-arrival distribution we establish a local limit theorem, capturing thus the sharp asymptotic behavior of correlations.

  13. Statistical mechanics of homogeneous partly pinned fluid systems

    E-Print Network [OSTI]

    Vincent Krakoviack

    2010-12-05

    The homogeneous partly pinned fluid systems are simple models of a fluid confined in a disordered porous matrix obtained by arresting randomly chosen particles in a one-component bulk fluid or one of the two components of a binary mixture. In this paper, their configurational properties are investigated. It is shown that a peculiar complementarity exists between the mobile and immobile phases, which originates from the fact that the solid is prepared in presence of and in equilibrium with the adsorbed fluid. Simple identities follow, which connect different types of configurational averages, either relative to the fluid-matrix system or to the bulk fluid from which it is prepared. Crucial simplifications result for the computation of important structural quantities, both in computer simulations and in theoretical approaches. Finally, possible applications of the model in the field of dynamics in confinement or in strongly asymmetric mixtures are suggested.

  14. Growth Kinetics of the Homogeneously Nucleated Water Droplets: Simulation Results

    E-Print Network [OSTI]

    Mokshin, Anatolii V; 10.1088/1742-6596/394/1/012023

    2012-01-01

    The growth of homogeneously nucleated droplets in water vapor at the fixed temperatures T=273, 283, 293, 303, 313, 323, 333, 343, 353, 363 and 373 K (the pressure $p=1$ atm.) is investigated on the basis of the coarse-grained molecular dynamics simulation data with the mW-model. The treatment of simulation results is performed by means of the statistical method within the mean-first-passage-time approach, where the reaction coordinate is associated with the largest droplet size. It is found that the water droplet growth is characterized by the next features: (i) the rescaled growth law is unified at all the considered temperatures and (ii) the droplet growth evolves with acceleration and follows the power law.

  15. The manufacture and performance of homogeneous microstructure SBR MOX fuel

    SciTech Connect (OSTI)

    Barker, Matthew A.; Stephenson, Keith; Weston, Rebecca

    2007-07-01

    In the early 1980's, British experience in the manufacture of mixed-oxide fast reactor fuel was used to develop a new thermal MOX manufacturing route called the Short Binder-less Route (SBR). Laboratory- scale development led to the manufacture of commercial PWR fuel in a small pilot plant, and the construction of the full-scale dual-line Sellafield MOX Plant (SMP). SMP's first MOX assemblies are now under irradiation. SBR MOX is manufactured with 100% co-milled feedstock, leading to a microstructure dominated by a solid solution of (U,Pu)O{sub 2} at the nominal enrichment. A comprehensive fuel performance research programme has demonstrated the benign performance of SBR MOX up to 54 MWd/kgHM. In particular, the homogeneous microstructure is believed to be instrumental in the favourable fission gas retention and PCI resistance properties. (authors)

  16. Homogenization limit for a multiband effective mass model in heterostructures

    SciTech Connect (OSTI)

    Morandi, O.

    2014-06-15

    We study the homogenization limit of a multiband model that describes the quantum mechanical motion of an electron in a quasi-periodic crystal. In this approach, the distance among the atoms that constitute the material (lattice parameter) is considered a small quantity. Our model include the description of materials with variable chemical composition, intergrowth compounds, and heterostructures. We derive the effective multiband evolution system in the framework of the kp approach. We study the well posedness of the mathematical problem. We compare the effective mass model with the standard kp models for uniform and non-uniforms crystals. We show that in the limit of vanishing lattice parameter, the particle density obtained by the effective mass model, converges to the exact probability density of the particle.

  17. Rotation Rate of Particle Pairs in Homogeneous Isotropic Turbulence

    E-Print Network [OSTI]

    Daddi-Moussa-Ider, Abdallah

    2015-01-01

    Understanding the dynamics of particles in turbulent flow is important in many environmental and industrial applications. In this paper, the statistics of particle pair orientation is numerically studied in homogeneous isotropic turbulent flow, with Taylor microscale Rynolds number of 300. It is shown that the Kolmogorov scaling fails to predict the observed probability density functions (PDFs) of the pair rotation rate and the higher order moments accurately. Therefore, a multifractal formalism is derived in order to include the intermittent behavior that is neglected in the Kolmogorov picture. The PDFs of finding the pairs at a given angular velocity for small relative separations, reveals extreme events with stretched tails and high kurtosis values. Additionally, The PDFs are found to be less intermittent and follow a complementary error function distribution for larger separations.

  18. Optimal thermalization in a shell model of homogeneous turbulence

    E-Print Network [OSTI]

    Thalabard, Simon

    2015-01-01

    We investigate the turbulence-induced dissipation of the large scales in a statistically homogeneous flow using an "optimal closure," which one of us (BT) has recently exposed in the context of Hamiltonian dynamics. This statistical closure employs a Gaussian model for the turbulent scales, with corresponding vanishing third cumulant, and yet it captures an intrinsic damping. The key to this apparent paradox lies in a clear distinction between true ensemble averages and their proxies, most easily grasped when one works directly with the Liouville equation rather than the cumulant hierarchy. We focus on a simple problem for which the optimal closure can be fully and exactly worked out: the relaxation arbitrarily far-from-equilibrium of a single energy shell towards Gibbs equilibrium in an inviscid shell model of 3D turbulence. The predictions of the optimal closure are validated against DNS and contrasted with those derived from EDQNM closure.

  19. Markovian Search Games in Heterogeneous Spaces

    SciTech Connect (OSTI)

    Griffin, Christopher H [ORNL

    2009-01-01

    We consider how to search for a mobile evader in a large heterogeneous region when sensors are used for detection. Sensors are modeled using probability of detection. Due to environmental effects, this probability will not be constant over the entire region. We map this problem to a graph search problem and, even though deterministic graph search is NP-complete, we derive a tractable, optimal, probabilistic search strategy. We do this by defining the problem as a differential game played on a Markov chain. We prove that this strategy is optimal in the sense of Nash. Simulations of an example problem illustrate our approach and verify our claims.

  20. Heterogeneously integrated microsystem-on-a-chip

    DOE Patents [OSTI]

    Chanchani, Rajen (Albuquerque, NM)

    2008-02-26

    A microsystem-on-a-chip comprises a bottom wafer of normal thickness and a series of thinned wafers can be stacked on the bottom wafer, glued and electrically interconnected. The interconnection layer comprises a compliant dielectric material, an interconnect structure, and can include embedded passives. The stacked wafer technology provides a heterogeneously integrated, ultra-miniaturized, higher performing, robust and cost-effective microsystem package. The highly integrated microsystem package, comprising electronics, sensors, optics, and MEMS, can be miniaturized both in volume and footprint to the size of a bottle-cap or less.

  1. INITIAL ANALYSIS OF TRANSIENT POWER TIME LAG DUE TO HETEROGENEITY WITHIN THE TREAT FUEL MATRIX.

    SciTech Connect (OSTI)

    D.M. Wachs; A.X. Zabriskie, W.R. Marcum

    2014-06-01

    The topic Nuclear Safety encompasses a broad spectrum of focal areas within the nuclear industry; one specific aspect centers on the performance and integrity of nuclear fuel during a reactivity insertion accident (RIA). This specific accident has proven to be fundamentally difficult to theoretically characterize due to the numerous empirically driven characteristics that quantify the fuel and reactor performance. The Transient Reactor Test (TREAT) facility was designed and operated to better understand fuel behavior under extreme (i.e. accident) conditions; it was shutdown in 1994. Recently, efforts have been underway to commission the TREAT facility to continue testing of advanced accident tolerant fuels (i.e. recently developed fuel concepts). To aid in the restart effort, new simulation tools are being used to investigate the behavior of nuclear fuels during facility’s transient events. This study focuses specifically on the characterizing modeled effects of fuel particles within the fuel matrix of the TREAT. The objective of this study was to (1) identify the impact of modeled heterogeneity within the fuel matrix during a transient event, and (2) demonstrate acceptable modeling processes for the purpose of TREAT safety analyses, specific to fuel matrix and particle size. Hypothetically, a fuel that is dominantly heterogeneous will demonstrate a clearly different temporal heating response to that of a modeled homogeneous fuel. This time difference is a result of the uniqueness of the thermal diffusivity within the fuel particle and fuel matrix. Using MOOSE/BISON to simulate the temperature time-lag effect of fuel particle diameter during a transient event, a comparison of the average graphite moderator temperature surrounding a spherical particle of fuel was made for both types of fuel simulations. This comparison showed that at a given time and with a specific fuel particle diameter, the fuel particle (heterogeneous) simulation and the homogeneous simulation were related by a multiplier relative to the average moderator temperature. As time increases the multiplier is comparable to the factor found in a previous analytical study from literature. The implementation of this multiplier and the method of analysis may be employed to remove assumptions and increase fidelity for future research on the effect of fuel particles during transient events.

  2. The Role of Interstitial Sites in the Ti3d Defect State

    E-Print Network [OSTI]

    , is used in a number of technological areas, includ- ing heterogeneous catalysis, photocatalysis, solar

  3. Probing the Impact of the EchinT C-Terminal Domain on Structure and Catalysis

    SciTech Connect (OSTI)

    S Bardaweel; J Pace; T Chou; V Cody; C Wagner

    2011-12-31

    Histidine triad nucleotide binding protein (Hint) is considered as the ancestor of the histidine triad protein superfamily and is highly conserved from bacteria to humans. Prokaryote genomes, including a wide array of both Gram-negative bacteria and Gram-positive bacteria, typically encode one Hint gene. The cellular function of Hint and the rationale for its evolutionary conservation in bacteria have remained a mystery. Despite its ubiquity and high sequence similarity to eukaryote Hint1 [Escherichia coli Hint (echinT) is 48% identical with human Hint1], prokaryote Hint has been reported in only a few studies. Here we report the first conformational information on the full-length N-terminal and C-terminal residues of Hint from the E. coli complex with GMP. Structural analysis of the echinT-GMP complex reveals that it crystallizes in the monoclinic space group P2{sub 1} with four homodimers in the asymmetric unit. Analysis of electron density for both the N-terminal residues and the C-terminal residues of the echinT-GMP complex indicates that the loops in some monomers can adopt more than one conformation. The observation of conformational flexibility in terminal loop regions could explain the presence of multiple homodimers in the asymmetric unit of this structure. To explore the impact of the echinT C-terminus on protein structure and catalysis, we conducted a series of catalytic radiolabeling and kinetic experiments on the C-terminal deletion mutants of echinT. In this study, we show that sequential deletion of the C-terminus likely has no effect on homodimerization and a modest effect on the secondary structure of echinT. However, we observed a significant impact on the folding structure, as reflected by a significant lowering of the T{sub m} value. Kinetic analysis reveals that the C-terminal deletion mutants are within an order of magnitude less efficient in catalysis compared to wild type, while the overall kinetic mechanism that proceeds through a fast step, followed by a rate-limiting hydrolysis step, was conserved. Nevertheless, the ability of the C-terminal deletion mutants to hydrolyze lysyl-AMP generated by LysU was greatly impaired. Taken together, our results highlight the emerging role of the C-terminus in governing the catalytic function of Hints.

  4. Intratumor heterogeneity alters most effective drugs in designed combinations

    E-Print Network [OSTI]

    Zhao, Boyang

    The substantial spatial and temporal heterogeneity observed in patient tumors poses considerable challenges for the design of effective drug combinations with predictable outcomes. Currently, the implications of tissue ...

  5. Pool Heterogeneity and the Valuation of Mortgage-Backed Securities

    E-Print Network [OSTI]

    Stanton, Richard

    1992-01-01

    Van Drunen. “Pricing Mortgage Pools with Heterogeneous Mort-shows proportion of pools in sample with estimated ? fallingmethodology for deriving pool-speci?c mortgage-backed

  6. Optimization of the dynamic behavior of strongly nonlinear heterogeneous materials

    E-Print Network [OSTI]

    Herbold, Eric B.

    2008-01-01

    dissimilar granular materials) and for optimization of shockOptimization of Dynamic Behavior in Heterogeneous Materials (band-gap materials and structures by topology optimization.

  7. Feedbacks between hydrological heterogeneity and bioremediation induced biogeochemical transformations

    E-Print Network [OSTI]

    Englert, A.

    2009-01-01

    Water Resources Research 2008, 44, W10412, doi:10.1029/2007WR006425. Supporting Information Feedbacks Between Hydrological Heterogeneity and Bioremediation

  8. Dose homogeneity specification for reference dosimetry of nonstandard fields

    SciTech Connect (OSTI)

    Chung, Eunah; Soisson, Emilie; Seuntjens, Jan [Medical Physics Unit, McGill University, Montreal General Hospital (L5-113), 1650 Cedar Avenue, Montreal, Quebec H3G 1A4 (Canada); Medical Physics Unit, McGill University and Department of Medical Physics, McGill University Health Centre, Montreal General Hospital (L5-113), 1650 Cedar Avenue, Montreal, Quebec H3G 1A4 (Canada); Medical Physics Unit, McGill University, Montreal General Hospital (L5-113), 1650 Cedar Avenue, Montreal, Quebec H3G 1A4 (Canada)

    2012-01-15

    Purpose: To investigate the sensitivity of the plan-class specific correction factor to dose distributions in composite nonstandard field dosimetry. Methods: A cylindrical water-filled PMMA phantom was constructed at the center of which reference absorbed dose could be measured. Ten different TomoTherapy-based IMRT fields were created on the CT images of the phantom. The dose distribution for each IMRT field was estimated at the position of a radiation detector or ionization chamber. The dose in each IMRT field normalized to that in a reference 10 x 10 cm{sup 2} field was measured using a PTW micro liquid ion chamber. Based on the new dosimetry formalism, a plan-class specific correction factor k{sub Q{sub p{sub c{sub s{sub r,Q}{sup f{sub p}{sub c}{sub s}{sub r},f{sub r}{sub e}{sub f}}}}}} for each field was measured for two Farmer-type chambers, Exradin A12 and NE2571, as well as for a smaller Exradin A1SL chamber. The dependence of the measured correction factor on parameters characterizing dose distribution was analyzed. Results: Uncertainty on the plan-class specific correction factor measurement was in the range of 0.3%-0.5% and 0.3%-0.8% for the Farmer-type chambers and the Exradin A1SL, respectively. When the heterogeneity of the central region of the target volume was less than 5%, the correction factor did not differ from unity by more than 0.7% for the three air-filled ionization chambers. For more heterogeneous dose deliveries, the correction factor differed from unity by up to 2.4% for the Farmer-type chambers. For the Exradin A1SL, the correction factor was closer to unity due to the reduced effect of dose gradients, while it was highly variable in different IMRT fields because of a more significant impact of positioning uncertainties on the response of this chamber. Conclusions: The authors have shown that a plan-class specific correction factor can be specified as a function of plan evaluation parameters especially for Farmer-type chambers. This work provides a recipe based on quantifying dose distribution to accurately select air-filled ionization chamber correction factors for nonstandard fields.

  9. Sulfation of metal-organic framework: Opportunities for acid catalysis and proton conductivity

    SciTech Connect (OSTI)

    Goesten, M.G.; Stavitski, E.; Juan-Alcaniz, J.; Ramos-Fernandez, E.V.; Sai Sankar Gupta, K.B.; van Bekkum, H.; Gascon, J. and Kapteijn, F.

    2011-05-24

    A new post-functionalization method for metal-organic frameworks (MOFs) has been developed to introduce acidity for catalysis. Upon treatment with a mixture of triflic anhydride and sulfuric acid, chemically stable MOF structures MIL-101(Cr) and MIL-53(Al) can be sulfated, resulting in a Broensted sulfoxy acid group attached to up to 50% of the aromatic terephthalate linkers of the structure. The sulfated samples have been extensively characterized by solid-state NMR, XANES, and FTIR spectroscopy. The functionalized acidic frameworks show catalytic activity similar to that of acidic polymers like Nafion{reg_sign} display in the esterification of n-butanol with acetic acid (TOF {approx} 1 min{sup -1} {at} 343 K). Water adsorbs strongly up to 4 molecules per sulfoxy acid group, and an additional 2 molecules are taken up at lower temperatures in the 1-D pore channels of S-MIL-53(Al). The high water content and Broensted acidity provide the structure S-MIL-53(Al) a high proton conductivity up to moderate temperatures.

  10. Molecular Insights into Substrate Recognition and Catalysis by Tryptophan 2,3-dioxygenase

    SciTech Connect (OSTI)

    Forouhar,F.; Ross Anderson, J.; Mowat, C.; Vorobiev, S.; Hussain, A.; Abashidze, M.; Bruckmann, C.; Thackray, S.; Seetharaman, J.; et al.

    2007-01-01

    Tryptophan 2,3-dioxygenase (TDO) and indoleamine 2,3-dioxygenase (IDO) constitute an important, yet relatively poorly understood, family of heme-containing enzymes. Here, we report extensive structural and biochemical studies of the Xanthomonas campestris TDO and a related protein SO4414 from Shewanella oneidensis, including the structure at 1.6-{angstrom} resolution of the catalytically active, ferrous form of TDO in a binary complex with the substrate l-Trp. The carboxylate and ammonium moieties of tryptophan are recognized by electrostatic and hydrogen-bonding interactions with the enzyme and a propionate group of the heme, thus defining the l-stereospecificity. A second, possibly allosteric, l-Trp-binding site is present at the tetramer interface. The sixth coordination site of the heme-iron is vacant, providing a dioxygen-binding site that would also involve interactions with the ammonium moiety of l-Trp and the amide nitrogen of a glycine residue. The indole ring is positioned correctly for oxygenation at the C2 and C3 atoms. The active site is fully formed only in the binary complex, and biochemical experiments confirm this induced-fit behavior of the enzyme. The active site is completely devoid of water during catalysis, which is supported by our electrochemical studies showing significant stabilization of the enzyme upon substrate binding.

  11. Dynamic control of a homogeneous charge compression ignition engine

    DOE Patents [OSTI]

    Duffy, Kevin P. (Metamora, IL); Mehresh, Parag (Peoria, IL); Schuh, David (Peoria, IL); Kieser, Andrew J. (Morton, IL); Hergart, Carl-Anders (Peoria, IL); Hardy, William L. (Peoria, IL); Rodman, Anthony (Chillicothe, IL); Liechty, Michael P. (Chillicothe, IL)

    2008-06-03

    A homogenous charge compression ignition engine is operated by compressing a charge mixture of air, exhaust and fuel in a combustion chamber to an autoignition condition of the fuel. The engine may facilitate a transition from a first combination of speed and load to a second combination of speed and load by changing the charge mixture and compression ratio. This may be accomplished in a consecutive engine cycle by adjusting both a fuel injector control signal and a variable valve control signal away from a nominal variable valve control signal. Thereafter in one or more subsequent engine cycles, more sluggish adjustments are made to at least one of a geometric compression ratio control signal and an exhaust gas recirculation control signal to allow the variable valve control signal to be readjusted back toward its nominal variable valve control signal setting. By readjusting the variable valve control signal back toward its nominal setting, the engine will be ready for another transition to a new combination of engine speed and load.

  12. Solar energy storage through the homogeneous electrocatalytic reduction of carbon dioxide : photoelectrochemical and photovoltaic approaches

    E-Print Network [OSTI]

    Sathrum, Aaron John

    2011-01-01

    electricity from photovoltaic cells to convert CO 2 intoSolar Energy Anode Photovoltaic Cell Cathode PP Mesh SpacerCoupling a Photovoltaic Solar Cell with a Homogeneous

  13. Effect of ambient conditions and fuel properties on homogeneous charge compression ignition engine operation

    E-Print Network [OSTI]

    Andreae, Morgan M. (Morgan MacKenzie)

    2006-01-01

    Practical application of Homogeneous Charge Compression Ignition (HCCI) combustion must demonstrate robust responses to variations in environmental conditions. This work examines the impact of ambient conditions and fuel ...

  14. Method of fabricating a homogeneous wire of inter-metallic alloy

    DOE Patents [OSTI]

    Ohriner, Evan Keith (Knoxville, TN); Blue, Craig Alan (Knoxville, TN)

    2001-01-01

    A method for fabricating a homogeneous wire of inter-metallic alloy comprising the steps of providing a base-metal wire bundle comprising a metal, an alloy or a combination thereof; working the wire bundle through at least one die to obtain a desired dimension and to form a precursor wire; and, controllably heating the precursor wire such that a portion of the wire will become liquid while simultaneously maintaining its desired shape, whereby substantial homogenization of the wire occurs in the liquid state and additional homogenization occurs in the solid state resulting in a homogenous alloy product.

  15. Heterogeneous Force Chains in Cellularized Biopolymer Network

    E-Print Network [OSTI]

    Liang, Long; Sun, Bo; Jiao, Yang

    2015-01-01

    Biopolymer Networks play an important role in coordinating and regulating collective cellular dynamics via a number of signaling pathways. Here, we investigate the mechanical response of a model biopolymer network due to the active contraction of embedded cells. Specifically, a graph (bond-node) model derived from confocal microscopy data is used to represent the network microstructure, and cell contraction is modeled by applying correlated displacements at specific nodes, representing the focal adhesion sites. A force-based stochastic relaxation method is employed to obtain force-balanced network under cell contraction. We find that the majority of the forces are carried by a small number of heterogeneous force chains emitted from the contracting cells. The force chains consist of fiber segments that either possess a high degree of alignment before cell contraction or are aligned due to the reorientation induced by cell contraction. Large fluctuations of the forces along different force chains are observed. ...

  16. Thermal Maps of Gases in Heterogeneous Reactions

    E-Print Network [OSTI]

    Jarenwattananon, Nanette N; Otto, Trenton; Melkonian, Arek; Morris, William; Burt, Scott R; Yaghi, Omar M; Bouchard, Louis-S

    2015-01-01

    Over 85% of all chemical industry products are made using catalysts, with the overwhelming majority of these employing heterogeneous catalysts functioning at the gas-solid interface. Consequently, optimizing catalytic reactor design attracts much effort. Such optimization relies on heat transfer and fluid dynamics modeling coupled to surface reaction kinetics. The complexity of these systems demands many approximations, which can only be tested with experimental observations of quantities such as temperature, pressure, concentrations, flow rates, etc. One essential measurement is a map of the spatial variation in temperature throughout the catalyst bed. We present here the first non-invasive maps of gas temperatures in catalyst-filled reactors, including high spatial resolution maps in microreactors enabled by parahydrogen. The thermal maps reveal energy flux patterns whose length scale correlates with the catalyst packing. By exploiting the motional averaging under a weak applied magnetic-field gradient, the...

  17. Dynamics on modular networks with heterogeneous correlations

    SciTech Connect (OSTI)

    Melnik, Sergey [MACSI, Department of Mathematics and Statistics, University of Limerick (Ireland) [MACSI, Department of Mathematics and Statistics, University of Limerick (Ireland); Oxford Centre for Industrial and Applied Mathematics, Mathematical Institute, University of Oxford, Oxford OX2 6GG (United Kingdom); CABDyN Complexity Centre, University of Oxford, Oxford OX1 1HP (United Kingdom); Porter, Mason A. [Oxford Centre for Industrial and Applied Mathematics, Mathematical Institute, University of Oxford, Oxford OX2 6GG (United Kingdom) [Oxford Centre for Industrial and Applied Mathematics, Mathematical Institute, University of Oxford, Oxford OX2 6GG (United Kingdom); CABDyN Complexity Centre, University of Oxford, Oxford OX1 1HP (United Kingdom); Mucha, Peter J. [Department of Mathematics, Carolina Center for Interdisciplinary Applied Mathematics, University of North Carolina, Chapel Hill, North Carolina 27599-3250 (United States) [Department of Mathematics, Carolina Center for Interdisciplinary Applied Mathematics, University of North Carolina, Chapel Hill, North Carolina 27599-3250 (United States); Institute for Advanced Materials, Nanoscience and Technology, University of North Carolina, Chapel Hill, North Carolina 27599-3216 (United States); Gleeson, James P. [MACSI, Department of Mathematics and Statistics, University of Limerick (Ireland)] [MACSI, Department of Mathematics and Statistics, University of Limerick (Ireland)

    2014-06-15

    We develop a new ensemble of modular random graphs in which degree-degree correlations can be different in each module, and the inter-module connections are defined by the joint degree-degree distribution of nodes for each pair of modules. We present an analytical approach that allows one to analyze several types of binary dynamics operating on such networks, and we illustrate our approach using bond percolation, site percolation, and the Watts threshold model. The new network ensemble generalizes existing models (e.g., the well-known configuration model and Lancichinetti-Fortunato-Radicchi networks) by allowing a heterogeneous distribution of degree-degree correlations across modules, which is important for the consideration of nonidentical interacting networks.

  18. Heterogeneous metasurface for high temperature selective emission

    SciTech Connect (OSTI)

    Woolf, D., E-mail: dwoolf@psicorp.com; Hensley, J. [Physical Sciences, Inc., 20 New England Business Center, Andover, Massachusetts 01810 (United States); Cederberg, J. G.; Bethke, D. T.; Grine, A. D.; Shaner, E. A. [Sandia National Laboratories, P.O. Box 5800, Albuquerque, New Mexico 87185 (United States)

    2014-08-25

    We demonstrate selective emission from a heterogeneous metasurface that can survive repeated temperature cycling at 1300?K. Simulations, fabrication, and characterization were performed for a cross-over-a-backplane metasurface consisting of platinum and alumina layers on a sapphire substrate. The structure was stabilized for high temperature operation by an encapsulating alumina layer. The geometry was optimized for integration into a thermophotovoltaic (TPV) system, and was designed to have its emissivity matched to the external quantum efficiency spectrum of 0.6?eV InGaAs TPV material. We present spectral measurements of the metasurface that result in a predicted 22% optical-to-electrical power conversion efficiency in a simplified model at 1300?K. Furthermore, this broadly adaptable selective emitter design can be easily integrated into full-scale TPV systems.

  19. Accelerating Subsurface Transport Simulation on Heterogeneous Clusters

    SciTech Connect (OSTI)

    Villa, Oreste; Gawande, Nitin A.; Tumeo, Antonino

    2013-09-23

    Reactive transport numerical models simulate chemical and microbiological reactions that occur along a flowpath. These models have to compute reactions for a large number of locations. They solve the set of ordinary differential equations (ODEs) that describes the reaction for each location through the Newton-Raphson technique. This technique involves computing a Jacobian matrix and a residual vector for each set of equation, and then solving iteratively the linearized system by performing Gaussian Elimination and LU decomposition until convergence. STOMP, a well known subsurface flow simulation tool, employs matrices with sizes in the order of 100x100 elements and, for numerical accuracy, LU factorization with full pivoting instead of the faster partial pivoting. Modern high performance computing systems are heterogeneous machines whose nodes integrate both CPUs and GPUs, exposing unprecedented amounts of parallelism. To exploit all their computational power, applications must use both the types of processing elements. For the case of subsurface flow simulation, this mainly requires implementing efficient batched LU-based solvers and identifying efficient solutions for enabling load balancing among the different processors of the system. In this paper we discuss two approaches that allows scaling STOMP's performance on heterogeneous clusters. We initially identify the challenges in implementing batched LU-based solvers for small matrices on GPUs, and propose an implementation that fulfills STOMP's requirements. We compare this implementation to other existing solutions. Then, we combine the batched GPU solver with an OpenMP-based CPU solver, and present an adaptive load balancer that dynamically distributes the linear systems to solve between the two components inside a node. We show how these approaches, integrated into the full application, provide speed ups from 6 to 7 times on large problems, executed on up to 16 nodes of a cluster with two AMD Opteron 6272 and a Tesla M2090 per node.

  20. On the Throughput Capacity of Heterogeneous Wireless Networks

    E-Print Network [OSTI]

    Latchman, Haniph A.

    On the Throughput Capacity of Heterogeneous Wireless Networks Pan Li, Member, IEEE, and Yuguang of wireless networks. However, it is commonly assumed that all nodes in the network are identical. The issue of heterogeneous wireless networks with general network settings. Specifically, we consider an extended network

  1. Dynamic Resource Management in Energy Constrained Heterogeneous Computing

    E-Print Network [OSTI]

    Maciejewski, Anthony A.

    Dynamic Resource Management in Energy Constrained Heterogeneous Computing Systems Using Voltage) in a manner that exploits the heterogeneity of the resources and tasks while considering the energy the resources are wireless and mobile, the limited battery capacity becomes a constraint and power or energy

  2. Autonomous Demand Response in Heterogeneous Smart Grid Topologies

    E-Print Network [OSTI]

    Mohsenian-Rad, Hamed

    1 Autonomous Demand Response in Heterogeneous Smart Grid Topologies Hamed Narimani and Hamed-mails: narimani-hh@ec.iut.ac.ir and hamed@ee.ucr.edu Abstract--Autonomous demand response (DR) is scalable and has demand response systems in heterogeneous smart grid topologies. Keywords: Autonomous demand response

  3. Dynamic Lung Morphology of Methacholine-Induced Heterogeneous Bronchoconstriction

    E-Print Network [OSTI]

    Dynamic Lung Morphology of Methacholine-Induced Heterogeneous Bronchoconstriction Ben T. Chen and G). The method provides direct visualization of the venti- lated regions within the lung. Heterogeneous bronchoconstric- tion following the i.v. MCh injection was evident using this technique. These 3 He dynamic lung

  4. Global Cost Diversity Aware Dispatch Algorithm for Heterogeneous Data Centers

    E-Print Network [OSTI]

    Fedorova, Alexandra

    Global Cost Diversity Aware Dispatch Algorithm for Heterogeneous Data Centers Ananth Narayan S. ans centers located across the globe. These data centers often house a heterogeneous computing infrastruc exploits both the data center het- erogeneity and global electricity market diversity to reduce data center

  5. Cooperative Decentralized Resource Allocation in Heterogeneous Wireless Access Medium

    E-Print Network [OSTI]

    Zhuang, Weihua

    1 Cooperative Decentralized Resource Allocation in Heterogeneous Wireless Access Medium Muhammad--In this paper, radio resource allocation in a hetero- geneous wireless access medium is investigated. Mobile the performance tradeoffs of the proposed algorithm. Index Terms--Heterogeneous wireless networks, resource allo

  6. Thermal Properties of Graphene-Copper-Graphene Heterogeneous Pradyumna Goli,

    E-Print Network [OSTI]

    Thermal Properties of Graphene-Copper-Graphene Heterogeneous Films Pradyumna Goli, Hao Ning that gra- phene-Cu-graphene heterogeneous films reveal strongly enhanced thermal conductivity as compared to the reference Cu and annealed Cu films. Chemical vapor deposition of a single atomic plane of graphene on both

  7. An Efficient Stochastic Clustering Auction for Heterogeneous Robot Teams

    E-Print Network [OSTI]

    Barbu, Adrian

    An Efficient Stochastic Clustering Auction for Heterogeneous Robot Teams Kai Zhang and Emmanuel G for effective coordination of heterogeneous robotic systems have numerous applications. For example, they can be used for efficient task allocation for teams of robots in many application domains [1], [2] such as col

  8. Process Migration for Heterogeneous Distributed Systems Matt Bishop

    E-Print Network [OSTI]

    Process Migration for Heterogeneous Distributed Systems Matt Bishop Department of Computer Science and mechanisms for migrating processes in a distributed system become more complicated in a heterogeneous the means to migrate processes to the idle resources. In this paper, we present a graph model for single

  9. THE EFFECT OF HETEROGENEITY IN TEAMS OF 100+ MOBILE ROBOTS

    E-Print Network [OSTI]

    Parker, Lynne E.

    THE EFFECT OF HETEROGENEITY IN TEAMS OF 100+ MOBILE ROBOTS Lynne E. Parker Department of Computer Science The University of Tennessee Knoxville, Tennessee USA parker@cs.utk.edu in Multi-Robot Systems for Distributed Robotics (SDR) Program, aimed at the practical implementation of a team of 100+ heterogeneous

  10. Heterogeneous Hardware Accelerator Architecture for Streaming Image Processing

    E-Print Network [OSTI]

    Bertels, Koen

    Heterogeneous Hardware Accelerator Architecture for Streaming Image Processing Cuong PhamCuong,Z.Al-Ars,K.L.M.Bertels}@tudelft.nl Abstract--This paper proposes a heterogeneous hardware-processed on a host processor and sent to hardware kernels. The host processor and the hardware kernels process

  11. An Availability-Aware Task Scheduling Strategy for Heterogeneous Systems

    E-Print Network [OSTI]

    Xie, Tao

    An Availability-Aware Task Scheduling Strategy for Heterogeneous Systems Xiao Qin, Member, IEEE, and Tao Xie, Member, IEEE Abstract--High availability is a key requirement in the design and development of heterogeneous systems where processors operate at different speeds and are not continuously available

  12. SU-E-J-63: Estimating the Effects of Respiratory Motion On Dose Heterogeneity for ITV-Based Treatments

    SciTech Connect (OSTI)

    Williams, C; Lewis, J

    2014-06-01

    Purpose: To quantify the relationship between the amount of dose heterogeneity in a treatment plan that uses an internal target volume (ITV) to account for respiratory motion and the true amount of heterogeneity in the dose delivered to the tumor contained within that ITV. Methods: We develop a convolution-based framework for calculating dose delivered to a tumor moving inside an ITV according to a common sinusoid-based breathing model including asymmetry. We model the planned ITV dose distribution as a centrally peaked analytic function approximating the profile of clinical stereotactic body radiotherapy treatments. Expressions for the minimum and maximum dose received by the tumor are derived and evaluated for a range of clinically relevant parameters. Results of the model are validated with phantom measurements using an ion chamber array. Results: An analytic expression is presented for the maximum and minimum doses received by the tumor relative to the planned ITV dose. The tumor dose heterogeneity depends solely on the ratio of tumor size to ITV size, the peak dose in the planned ITV dose distribution, and the respiratory asymmetry parameter. Under the assumptions of this model, using a typical breathing asymmetry parameter and a dose distribution with a fixed size ITV covered by the 100% line and with a 130% hotspot, the maximum dose to the tumor varies between 113%–130%, and the minimum dose varies between 100%–116% depending on the amount of tumor motion. Conclusion: This modeling exercise demonstrates the interplay between motion and dose heterogeneity. Tumors that exhibit large amounts of respiratory motion relative to their size will receive a more homogeneous dose and a larger minimum dose than would be inferred from the ITV dose distribution. This effect is not captured in current clinical treatment planning methods unless 4D dose calculation techniques are used. This work was partially supported by a Varian Medical Systems research grant.

  13. Low Frequency Scattering Resonance Wave in Strong Heterogeneity

    E-Print Network [OSTI]

    Liu, Yinbin

    2015-01-01

    Multiple scattering of wave in strong heterogeneity can cause resonance-like wave phenomenon where signal exhibits low frequency, high intensity, and slowly propagating velocity. For example, long period event in volcanic seismology and surface plasmon wave and quantum Hall effect in wave-particle interactions. Collective behaviour in a many-body system is usually thought to be the source for generating the anomaly. However, the detail physical mechanism is not fully understood. Here I show by wave field modeling for microscopic bubble cloud model and 1D heterogeneity that the anomaly is related to low frequency scattering resonance happened in transient regime. This low frequency resonance is a kind of wave coherent scattering enhancement phenomenon in strongly-scattered small-scale heterogeneity. Its resonance frequency is inversely proportional to heterogeneous scale and contrast and will further shift toward lower frequency with random heterogeneous scale and velocity fluctuations. Low frequency scatterin...

  14. An Innovative Three-Dimensional Heterogeneous Coarse-Mesh Transport Method for Advanced and Generation IV Reactor Core Analysis and Design

    SciTech Connect (OSTI)

    Farzad Rahnema

    2009-11-12

    This project has resulted in a highly efficient method that has been shown to provide accurate solutions to a variety of 2D and 3D reactor problems. The goal of this project was to develop (1) an accurate and efficient three-dimensional whole-core neutronics method with the following features: based sollely on transport theory, does not require the use of cross-section homogenization, contains a highly accurate and self-consistent global flux reconstruction procedure, and is applicable to large, heterogeneous reactor models, and to (2) create new numerical benchmark problems for code cross-comparison.

  15. Application of the Hanbury BrownTwiss effect to scattering from quasi-homogeneous media

    E-Print Network [OSTI]

    Visser, Taco D.

    Application of the Hanbury Brown­Twiss effect to scattering from quasi-homogeneous media David: Hanbury Brown-Twiss effect Scattering Born approximation Quasi-homogeneous media Inverse scattering a b scattering media, is studied by the use of the Hanbury Brown­Twiss effect. In particular the two

  16. Analysis of Molten Carbonate Fuel Cell Performance Using a Three-Phase Homogeneous Model

    E-Print Network [OSTI]

    Popov, Branko N.

    Analysis of Molten Carbonate Fuel Cell Performance Using a Three-Phase Homogeneous Model N-phase homogeneous model was developed to simulate the performance of the molten carbonate fuel cell MCFC cathode received June 18, 2002. Available electronically November 15, 2002. Molten carbonate fuel cells MCFCs

  17. Homogeneous, dual layer, solid state, thin film deposition for structural and/or electrochemical characteristics

    DOE Patents [OSTI]

    Pitts, J. Roland; Lee, Se-Hee; Tracy, C. Edwin; Li, Wenming

    2014-04-08

    Solid state, thin film, electrochemical devices (10) and methods of making the same are disclosed. An exemplary device 10 includes at least one electrode (14) and an electrolyte (16) deposited on the electrode (14). The electrolyte (16) includes at least two homogenous layers of discrete physical properties. The two homogenous layers comprise a first dense layer (15) and a second porous layer (16).

  18. Thermal Decomposition of Dichlorosilane Investigated by Pulsed Laser Powered Homogeneous Pyrolysis

    E-Print Network [OSTI]

    Swihart, Mark T.

    Thermal Decomposition of Dichlorosilane Investigated by Pulsed Laser Powered Homogeneous Pyrolysis powered homogeneous pyrolysis of dichlorosilane are reported. Pyrolyses at temperatures of 1350 to 1700 K in both static pyrolysis exper- iments and using a single-pulse shock tube. They conclud- ed

  19. RECOVERING A TIME-HOMOGENEOUS STOCK PRICE PROCESS FROM PERPETUAL OPTION PRICES

    E-Print Network [OSTI]

    RECOVERING A TIME-HOMOGENEOUS STOCK PRICE PROCESS FROM PERPETUAL OPTION PRICES ERIK EKSTR¨OM AND DAVID HOBSON Abstract. It is well-known how to determine the price of perpetual American options if the underlying stock price is a time-homogeneous diffusion. In the present paper we consider the inverse problem

  20. ONE-DIMENSIONAL PSEUDO-HOMOGENEOUS PACKED BED REACTOR MODELING INCLUDING NO-CO KINETICS

    E-Print Network [OSTI]

    Srinivasan, Anand

    2011-08-31

    -homogeneous packed bed reactor model for this type of reactor setup built in collaboration with the Chemical and Petroleum Engineering Department at the University of Kansas. A brief summary of the pseudo-homogeneous model is presented in order to properly develop...

  1. Fluorescence Lifetime of Emitters with Broad Homogeneous Linewidths Modified in Opal Photonic Crystals

    E-Print Network [OSTI]

    Vos, Willem L.

    Fluorescence Lifetime of Emitters with Broad Homogeneous Linewidths Modified in Opal Photonic, 2008 We have investigated the dynamics of spontaneous emission from dye molecules embedded in opal optical frequency and crystal lattice parameter of the polystyrene opals. Due to the broad homogeneous

  2. Support for Speakers and Attendees at 2008 GRC Conference Catalysis (to be held at Colby Sawyer College, New London, New Hampshire on June 22-27, 2008)

    SciTech Connect (OSTI)

    Stuart L. Soled and Nancy Ryan Gray

    2009-01-01

    The GRC on Catalysis is one of the most prestigious catalysis conferences as it brings together leading researchers from around the world to discuss their latest, most exciting work in catalysis. The 2008 conference will continue this tradition. The conference will cover a variety of themes including new catalytic materials, theoretical and experimental approaches to improve understanding of kinetics and transport phenomena, and state of the art nanoscale characterization probes to monitor active sites. The conference promotes interactions among established researchers and young scientists. It provides a venue for students to meet, talk to and learn from some of the world leading researchers in the area. It also gives them a platform for displaying their own work during the poster sessions. The informal nature of the meeting, excellent quality of the presentations and posters, and ability to meet many outstanding colleagues makes this an excellent conference.

  3. Opportunities for Catalysis in The 21st Century. A report from the Basic Energy Sciences Advisory Committee

    SciTech Connect (OSTI)

    White, J. M.; Bercaw, J.

    2002-05-16

    Chemical catalysis affects our lives in myriad ways. Catalysis provides a means of changing the rates at which chemical bonds are formed and broken and of controlling the yields of chemical reactions to increase the amounts of desirable products from these reactions and reduce the amounts of undesirable ones. Thus, it lies at the heart of our quality of life: The reduced emissions of modern cars, the abundance of fresh food at our stores, and the new pharmaceuticals that improve our health are made possible by chemical reactions controlled by catalysts. Catalysis is also essential to a healthy economy: The petroleum, chemical, and pharmaceutical industries, contributors of $500 billion to the gross national product of the United States, rely on catalysts to produce everything from fuels to ''wonder drugs'' to paints to cosmetics. Today, our Nation faces a variety of challenges in creating alternative fuels, reducing harmful by-products in manufacturing, cleaning up the environment and preventing future pollution, dealing with the causes of global warming, protecting citizens from the release of toxic substances and infectious agents, and creating safe pharmaceuticals. Catalysts are needed to meet these challenges, but their complexity and diversity demand a revolution in the way catalysts are designed and used. This revolution can become reality through the application of new methods for synthesizing and characterizing molecular and material systems. Opportunities to understand and predict how catalysts work at the atomic scale and the nanoscale are now appearing, made possible by breakthroughs in the last decade in computation, measurement techniques, and imaging and by new developments in catalyst design, synthesis, and evaluation.

  4. High Efficiency, Low Emissions Homogeneous Charge Compression Ignition (HCCI) Engines

    SciTech Connect (OSTI)

    2011-01-31

    This is the final report of the High Efficiency Clean Combustion (HECC) Research Program for the U.S. Department of Energy. Work under this co-funded program began in August 2005 and finished in July 2010. The objective of this program was to develop and demonstrate a low emission, high thermal efficiency engine system that met 2010 EPA heavy-duty on-highway truck emissions requirements (0.2g/bhp-hr NOx, 0.14g/bhp-hr HC and 0.01g/bhp-hr PM) with a thermal efficiency of 46%. To achieve this goal, development of diesel homogenous charge compression ignition (HCCI) combustion was the chosen approach. This report summarizes the development of diesel HCCI combustion and associated enabling technologies that occurred during the HECC program between August 2005 and July 2010. This program showed that although diesel HCCI with conventional US diesel fuel was not a feasible means to achieve the program objectives, the HCCI load range could be increased with a higher volatility, lower cetane number fuel, such as gasoline, if the combustion rate could be moderated to avoid excessive cylinder pressure rise rates. Given the potential efficiency and emissions benefits, continued research of combustion with low cetane number fuels and the effects of fuel distillation are recommended. The operation of diesel HCCI was only feasible at part-load due to a limited fuel injection window. A 4% fuel consumption benefit versus conventional, low-temperature combustion was realized over the achievable operating range. Several enabling technologies were developed under this program that also benefited non-HCCI combustion. The development of a 300MPa fuel injector enabled the development of extended lifted flame combustion. A design methodology for minimizing the heat transfer to jacket water, known as precision cooling, will benefit conventional combustion engines, as well as HCCI engines. An advanced combustion control system based on cylinder pressure measurements was developed. A Well-to-wheels analysis of the energy flows in a mobile vehicle system and a 2nd Law thermodynamic analysis of the engine system were also completed under this program.

  5. Heterogeneous Force Chains in Cellularized Biopolymer Network

    E-Print Network [OSTI]

    Long Liang; Christopher Jones; Bo Sun; Yang Jiao

    2015-08-18

    Biopolymer Networks play an important role in coordinating and regulating collective cellular dynamics via a number of signaling pathways. Here, we investigate the mechanical response of a model biopolymer network due to the active contraction of embedded cells. Specifically, a graph (bond-node) model derived from confocal microscopy data is used to represent the network microstructure, and cell contraction is modeled by applying correlated displacements at specific nodes, representing the focal adhesion sites. A force-based stochastic relaxation method is employed to obtain force-balanced network under cell contraction. We find that the majority of the forces are carried by a small number of heterogeneous force chains emitted from the contracting cells. The force chains consist of fiber segments that either possess a high degree of alignment before cell contraction or are aligned due to the reorientation induced by cell contraction. Large fluctuations of the forces along different force chains are observed. Importantly, the decay of the forces along the force chains is significantly slower than the decay of radially averaged forces in the system. These results suggest that the fibrous nature of biopolymer network structure can support long-range force transmission and thus, long-range mechanical signaling between cells.

  6. Coordinated Collaboration between Heterogeneous Distributed Energy Resources

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Abdollahy, Shahin; Lavrova, Olga; Mammoli, Andrea

    2014-01-01

    A power distribution feeder, where a heterogeneous set of distributed energy resources is deployed, is examined by simulation. The energy resources include PV, battery storage, natural gas GenSet, fuel cells, and active thermal storage for commercial buildings. The resource scenario considered is one that may exist in a not too distant future. Two cases of interaction between different resources are examined. One interaction involves a GenSet used to partially offset the duty cycle of a smoothing battery connected to a large PV system. The other example involves the coordination of twenty thermal storage devices, each associated with a commercial building.more »Storage devices are intended to provide maximum benefit to the building, but it is shown that this can have a deleterious effect on the overall system, unless the action of the individual storage devices is coordinated. A network based approach is also introduced to calculate some type of effectiveness metric to all available resources which take part in coordinated operation. The main finding is that it is possible to achieve synergy between DERs on a system; however this required a unified strategy to coordinate the action of all devices in a decentralized way.« less

  7. The building blocks of dynamical heterogeneities in dense granular media

    E-Print Network [OSTI]

    R. Candelier; O. Dauchot; G. Biroli

    2009-01-22

    We investigate experimentally the connection between short time dynamics and long time dynamical heterogeneities within a dense granular media under cyclic shear. We show that dynamical heterogeneities result from a two timescales process. Short time but already collective events consisting in clustered cage jumps concentrate most of the non affine displacements. On larger timescales such clusters appear aggregated both temporally and spatially in avalanches which eventually build the large scales dynamical heterogeneities. Our results indicate that facilitation plays an important role in the relaxation process although it does not appear to be conserved as proposed in many models studied in the literature.

  8. Magnetically-Assisted Statistical Assembly - a new heterogeneous integration technique

    E-Print Network [OSTI]

    Fonstad, Clifton G. Jr.

    This paper presents a new technique for the monolithic heterogeneous integration of compound semiconductor devices with silicon integrated circuits, and establishes the theoretical foundation for a key element of the ...

  9. An approach to composing web services with context heterogeneity

    E-Print Network [OSTI]

    Madnick, Stuart E.

    The potential benefits of Web services composition heavily rely on semantic interoperability, i.e., the ability to exchange data meaningfully amongst Web services. Context heterogeneity, which refers to different implicit ...

  10. Dynamic sensor tasking in heterogeneous, mobile sensor networks

    E-Print Network [OSTI]

    Jones, Peter B. (Peter B.), S.M., Massachusetts Institute of Technology

    2005-01-01

    Modern sensor environments often attempt to combine several sensors into a single sensor network. The nodes of this network are generally heterogeneous and may vary with respect to sensor complexity, sensor operational ...

  11. Discrete Feature Approach for Heterogeneous Reservoir Production Enhancement

    SciTech Connect (OSTI)

    Dershowitz, William S.; Curran, Brendan; Einstein, Herbert; LaPointe, Paul; Shuttle, Dawn; Klise, Kate

    2002-07-26

    The report presents summaries of technology development for discrete feature modeling in support of the improved oil recovery (IOR) for heterogeneous reservoirs. In addition, the report describes the demonstration of these technologies at project study sites.

  12. PARTITIONED ANALYSIS FOR DIMENSIONALLY-HETEROGENEOUS HYDRAULIC NETWORKS*

    E-Print Network [OSTI]

    Buscaglia, Gustavo C.

    PARTITIONED ANALYSIS FOR DIMENSIONALLY-HETEROGENEOUS HYDRAULIC NETWORKS* JORGE S. LEIVA , PABLO J for which this procedure is envisaged arises when modeling hydraulic networks in which complex and simple

  13. Increasing Stability Reduces Conformational Heterogeneity in a Protein Folding

    E-Print Network [OSTI]

    Increasing Stability Reduces Conformational Heterogeneity in a Protein Folding Intermediate, the results show that protein folding intermediates are ensembles of different structural forms direct experi- mental evidence in support of a basic tenet of energy landscape theory for protein folding

  14. Adapting a delay-based protocol to heterogeneous environments 

    E-Print Network [OSTI]

    Kotla, Kiran

    2008-10-10

    We investigate the issues in making a delay-based protocol adaptive to heterogeneous environments. We assess and address the problems a delay-based protocol faces when competing with a loss-based protocol such as TCP. We ...

  15. OSCAR Parallelizing Compiler Cooperative Heterogeneous Multi-core Architecture

    E-Print Network [OSTI]

    Kasahara, Hironori

    OSCAR Parallelizing Compiler Cooperative Heterogeneous Multi-core Architecture Akihiro Hayashi, powerful parallelizing compiler for hetero- geneous multi-core architectures is expected. Furthermore, cooperative work between parallelizing compiler and hetero- geneous multi-core architectures is important

  16. A Parallelizing Compiler Cooperative Heterogeneous Multicore Processor Architecture

    E-Print Network [OSTI]

    Kasahara, Hironori

    A Parallelizing Compiler Cooperative Heterogeneous Multicore Processor Architecture Yasutaka Wada and a parallelizing com- piler is important. This paper proposes a compiler cooperative hetero- geneous multicore architecture and parallelizing compilation scheme for it. Performance of the proposed scheme is evaluated

  17. Stabilization of Ion Concentration Polarization Using a Heterogeneous Nanoporous Junction

    E-Print Network [OSTI]

    Kim, Pilnam

    We demonstrate a recycled ion-flux through heterogeneous nanoporous junctions, which induce stable ion concentration polarization with an electric field. The nanoporous junctions are based on integration of ionic hydrogels ...

  18. The variation of apparent crown size and canopy heterogeneity across

    E-Print Network [OSTI]

    Malhi, Yadvinder

    , 2 IRD-UMR Botanique et Bioinformatique de l'Architecture des Plantes (AMAP), Boulevard de la Lironde and Africa. Some regions show significantly greater canopy heterogeneity, a feature that may be related

  19. Acid Fracturing Feasibility Study for Heterogeneous Carbonate Formation 

    E-Print Network [OSTI]

    Suleimenova, Assiya

    2015-03-03

    Acid fracturing is a stimulation technique that is commonly used by the industry to increase productivity or injectivity of wells in carbonate reservoirs. To determine a feasibility of acid fracturing treatment for a heterogeneous formation...

  20. MODELING PHOTOSYNTHESIS OF HETEROGENEOUS ROSE CROP CANOPIES IN THE GREENHOUSE

    E-Print Network [OSTI]

    Lieth, J. Heinrich

    MODELING PHOTOSYNTHESIS OF HETEROGENEOUS ROSE CROP CANOPIES IN THE GREENHOUSE Soo-Hyung Kim and J training system ("bent canopy") is widely used in greenhouse rose production. The bent canopy consists

  1. Entrainment of heterogeneous glycolytic oscillations in single cells

    E-Print Network [OSTI]

    Gustavsson, A -K; Mehlig, B; Goksör, M

    2015-01-01

    Cell signaling, gene expression, and metabolism are affected by cell-cell heterogeneity and random changes in the environment. The effects of such fluctuations on cell signaling and gene expression have recently been studied intensively using single-cell experiments. In metabolism heterogeneity may be particularly important because it may affect synchronisation of metabolic oscillations, an important example of cell-cell communication. This synchronisation is notoriously difficult to describe theoretically as the example of glycolytic oscillations shows: neither is the mechanism of glycolytic synchronisation understood nor the role of cell-cell heterogeneity. To pin down the mechanism and to assess its robustness and universality we have experimentally investigated the entrainment of glycolytic oscillations in individual yeast cells by periodic external perturbations. We find that oscillatory cells synchronise through phase shifts and that the mechanism is insensitive to cell heterogeneity (robustness) and si...

  2. Improved Modeling of Transition Metals, Applications to Catalysis and Technetium Chemistry

    SciTech Connect (OSTI)

    Cundari, T. R.

    2004-03-05

    There is considerable impetus for identification of aqueous OM catalysts as water is the ultimate ''green'' solvent. In collaboration with researchers at Ames Lab, we investigated effective fragment and Monte Carlo techniques for aqueous-phase hydroformylation (HyF). The Rh of the HyF catalyst is weakly aquated, in contrast to the hydride of the Rh-H bond. As the insertion of the olefin C=C into Rh-H determines the linear-to-branched aldehyde ratio, it is reasonable to infer that solvent plays an important role in regiochemistry. Studies on aqueous-phase organometallic catalysis were complemented in studies of the gas-phase reaction. A Rh-carbonyl-phosphine catalyst was investigated. Two of the most important implications of this research include (a) pseudorotation among five-coordinate intermediates is significant in HyF, and (b) CO insertion is the rate-determining step. The latter is in contrast to experimental deductions, highlighting the need for more accurate modeling. To this end, we undertook studies of (a) experimentally relevant PR{sub 3} co-ligands (PMe{sub 3}, PPh{sub 3}, P(p-PhSO{sub 3{sup -}}){sub 3}, etc.), and (b) HyF of propene. For the propylene research, simulations indicated that the linear: branched aldehyde ratio (linear is more desirable) is determined by thermodynamic discrimination of two distinct pathways. Other projects include a theory-experiment study of C-H activation by early transition metal systems, which establishes that weakly-bound adducts play a key role in activity selectivity. By extension, more selective catalysts for functionalization of methane (major component of natural gas) will require better understanding of these adducts, which are greatly affected by steric interactions with the ligands. In the de novo design of Tc complexes, we constructed (and are now testing) a coupled quantum mechanics-molecular mechanics protocol. Initial research shows it to be capable of accurately predicting structure ''from scratch.'' Challenges include conformational, geometric, coordination, spin, and particularly linkage (e.g., Tc-SCN versus Tc-NCS) isomerism. In general, our protocol can rapidly (<1 day with desktop software/hardware) predict the structure of diverse Tc complexes with an accuracy commensurate to organics. Our de novo strategy is also being used to investigate tris-pyrazolyl borate (Tp) complexes. Data suggests a fundamental difference in methane activation between TpRe and related CpRe complexes. Furthermore, Tp is a more electronically ''flexible'' platform for catalysts modification than Cp.

  3. Genetic heterogeneity in breast cancer: the road to personalized medicine?

    E-Print Network [OSTI]

    Baird, Richard D.; Caldas, Carlos

    2013-06-21

    , Alipaz J, Bauer MJ, Beare D, Butler A, Carter RJ, Chen L, Cox AJ, Edkins S, Kokko- Gonzales PI, Gormley NA, Grocock RJ, Haudenschild CD, Hims MM, James T, Jia M, Kingsbury Z, Leroy C, Marshall J, Menzies A, et al: A comprehensive catalogue of somatic... , Next-generation sequencing, W Personalized medicine, Heterogeneity The genetic heterogeneity seen in breast cancer has important clinical implications In 2008 it was estimated that the annual number of new breast cancer diagnoses globally...

  4. Genetic heterogeneity in breast cancer: the road to personalised medicine?

    E-Print Network [OSTI]

    Baird, Richard D.; Caldas, Carlos

    2013-06-18

    , Alipaz J, Bauer MJ, Beare D, Butler A, Carter RJ, Chen L, Cox AJ, Edkins S, Kokko- Gonzales PI, Gormley NA, Grocock RJ, Haudenschild CD, Hims MM, James T, Jia M, Kingsbury Z, Leroy C, Marshall J, Menzies A, et al: A comprehensive catalogue of somatic... . Keywords: Breast cancer, Next-generation sequencing, W Personalized medicine, Heterogeneity The genetic heterogeneity seen in breast cancer has important clinical implications In 2008 it was estimated that the annual number of new breast cancer diagnoses...

  5. The heterogeneous gas with singular interaction: Generalized circular law and heterogeneous renormalized energy

    E-Print Network [OSTI]

    Luis Carlos Garcia del Molino; Khashayar Pakdaman; Jonathan Touboul

    2014-10-26

    We introduce and analyze $d$ dimensional Coulomb gases with random charge distribution and general external confining potential. We show that these gases satisfy a large deviations principle. The analysis of the minima of the rate function (which is the leading term of the energy) reveals that at equilibrium, the particle distribution is a generalized circular law (i.e. with spherical support but non-necessarily uniform distribution). In the classical electrostatic external potential, there are infinitely many minimizers of the rate function. The most likely macroscopic configuration is a disordered distribution in which particles are uniformly distributed (for $d=2$, the circular law), and charges are independent of the positions of the particles. General charge-dependent confining potentials unfold this degenerate situation: in contrast, the particle density is not uniform, and particles spontaneously organize according to their charge. In that picture the classical electrostatic potential appears as a transition at which order is lost. Sub-leading terms of the energy are derived: we show that these are related to an operator, generalizing the Coulomb renormalized energy, which incorporates the heterogeneous nature of the charges. This heterogeneous renormalized energy informs us about the microscopic arrangements of the particles, which are non-standard, strongly depending on the charges, and include progressive and irregular lattices.

  6. New Iron(II) and Manganese(II) Complexes of Two Ultra-Rigid, Cross-Bridged Tetraazamacrocycles for Catalysis and Biomimicry

    E-Print Network [OSTI]

    Hubin, Tim

    for Catalysis and Biomimicry Timothy J. Hubin, James M. McCormick, Simon R. Collinson, Maria Buchalova, Christopher M. Perkins,§ Nathaniel W. Alcock, Pawan K. Kahol, Ahasuya Raghunathan, and Daryle H. Busch. (2) (a) Jang, H. G.; Cox, D. D.; Que, L., Jr. J. Am. Chem. Soc. 1991, 113, 9200. (b) Han, S.; Eltis

  7. Applied Catalysis A: General 192 (2000) 227234 Hydrogen production via the direct cracking of methane over Ni/SiO2

    E-Print Network [OSTI]

    zur Loye, Hans-Conrad

    2000-01-01

    Applied Catalysis A: General 192 (2000) 227­234 Hydrogen production via the direct cracking is a potential route to the production of CO-free hydrogen and filamentous carbon. Eventually, however. ©2000 Elsevier Science B.V. All rights reserved. Keywords: Methane cracking; Hydrogen production

  8. Direct measurements of ensemble particle and surface interactions on homogeneous and patterned substrates 

    E-Print Network [OSTI]

    Wu, Hung-Jen

    2006-08-16

    range particle-particle attraction and recovery of the expected DLVO particle-wall interactions for all concentrations examined. The possible influence of charge heterogeneity and particle size polydispersity on measured distribution functions...

  9. Line-tension-induced scenario of heterogeneous nucleation on a spherical substrate and in a spherical cavity

    E-Print Network [OSTI]

    Masao Iwamatsu

    2015-06-19

    Line-tension-induced {scenario of heterogeneous nucleation} is studied for a lens-shaped nucleus with a finite contact angle nucleated on a spherical substrate and on the bottom of the wall of a spherical cavity. The effect of line tension on the free energy of a critical nucleus can be separated from the usual volume term. By comparing the free energy of a lens-shaped critical nucleus of a finite contact angle with that of a spherical nucleus, we find that a spherical nucleus may have a lower free energy than a lens-shaped nucleus when the line tension is positive and large, which is similar to the drying transition predicted by Widom [B. Widom, J. Phys. Chem. {\\bf 99} 2803 (1995)]. Then, the homogeneous nucleation rather than the heterogeneous nucleation will be favorable. Similarly, the free energy of a lens-shaped nucleus becomes negative when the line tension is negative and large. Then, the barrier-less nucleation with no thermal activation called athermal nucleation will be realized.

  10. Generic solution of the heterogeneity-induced competing risk problem in survival analysis

    E-Print Network [OSTI]

    Coolen, ACC "Ton"

    Generic solution of the heterogeneity-induced competing risk problem in survival analysis J van competing risks to be induced by residual cohort heterogeneity, i.e. heterogeneity that is not captured risks that unifies the main schools of thought. Assuming heterogeneity-induced competing risks is much

  11. The MyView Project: from Heterogeneous Bibliographic Information Repositories to Personalized Digital Libraries

    E-Print Network [OSTI]

    Clausen, Michael

    at the integration of both structured and unstructured bibli­ ographic information from a diversity of heterogeneous

  12. Effect of homogenization pressure, lipid content, and emulsifier content on the rheological properties of yogurt 

    E-Print Network [OSTI]

    Jaar Sansur, Patricia Mary

    1998-01-01

    The interaction of high pressure homogenization lipid hics. content, and surfactant on the rheological properties of yogurt were evaluated. NFDM, cream, and a nontoxic emulsifier (Tween 20) were combined to obtain samples with of 0% and 2% fat...

  13. NUMERICAL METHODS FOR COMPUTING NONLINEAR EIGENPAIRS: PART II. NON ISO-HOMOGENEOUS CASES

    E-Print Network [OSTI]

    Zhou, Jianxin

    for solving the problems, we consider the following variational nonlinear eigenproblem (NEP): for given > 0 packages are available. When either F or G is nonlinear, (1.7) is a NEP. Recall that an NEP is homogeneous

  14. Thermodynamics In Einstein equation, the energy momentum tensor of homogeneous, isotropic

    E-Print Network [OSTI]

    Murayama, Hitoshi

    Thermodynamics In Einstein equation, the energy momentum tensor of homogeneous, isotropic fluid using the 1st law of thermodynamics, T = (U/S)V . Since U = V is expressed in terms of the temperature

  15. NOx-Mediated Homogeneous Pathways for the Synthesis of Formaldehyde from CH4-O2 Mixtures

    E-Print Network [OSTI]

    Iglesia, Enrique

    NOx-Mediated Homogeneous Pathways for the Synthesis of Formaldehyde from CH4-O2 Mixtures Jeffrey M-NOx reactions is used to estimate maximum attainable formaldehyde (and methanol) yields

  16. Direct current dielectric barrier assistant discharge to get homogeneous plasma in capacitive coupled discharge

    SciTech Connect (OSTI)

    Du, Yinchang; Li, Yangfang; Cao, Jinxiang; Liu, Yu; Wang, Jian; Zheng, Zhe

    2014-06-15

    In this paper, we propose a method to get more homogeneous plasma in the geometrically asymmetric capacitive coupled plasma (CCP) discharge. The dielectric barrier discharge (DBD) is used for the auxiliary discharge system to improve the homogeneity of the geometrically asymmetric CCP discharge. The single Langmuir probe measurement shows that the DBD can increase the electron density in the low density volume, where the DBD electrodes are mounted, when the pressure is higher than 5?Pa. By this manner, we are able to improve the homogeneity of the plasma production and increase the overall density in the target volume. At last, the finite element simulation results show that the DC bias, applied to the DBD electrodes, can increase the homogeneity of the electron density in the CCP discharge. The simulation results show a good agreement with the experiment results.

  17. A novel approach to make homogeneous protease-stable monovalent streptavidin

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Zhang, M.; Shao, J; Xiao, J.; Deng, W.; Yu, H.

    2015-06-11

    The interaction between the tetramer streptavidin and biotin is recognized as one of the strongest non-covalent associations. Owing to the tight and specific binding, the streptavidin-biotin system has been used widely for bimolecular labeling, purification, immobilization, and even for targeted delivery of therapeutics drugs. Here, we report a novel approach to make homogeneous monovalent tetramer streptavidin. The purified monovalent protein showed both thermal stability and protease stability. Unexpectedly, we found that two proteases, Proteinase K (PK) and Subtilisin (SU), can efficiently remove the His8-tag from the wild-type subunit without affecting the tetramer architecture of monovalent streptavidin, thus making it moremore »homogeneous. In addition, crystallization was performed to assure the homogeneity of the monovalent protein prepared. Overall, monovalent streptavidin shows increased homogeneity and will likely be valuable for many future applications in a wide range of research areas.« less

  18. Architectural Gear Ratio and Muscle Fiber Strain Homogeneity in Segmented Musculature

    E-Print Network [OSTI]

    Azizi, Manny

    axis of bending (vertebral column). In this study we use the relatively simple architecture homogeneity in segmented musculature. J. Exp. Zool. 307A:145­155. At the sarcomere level, all vertebrate

  19. Neutronic Assessment of Transmutation Target Compositions in Heterogeneous Sodium Fast Reactor Geometries

    SciTech Connect (OSTI)

    Samuel E. Bays; Rodolfo M. Ferrer; Michael A. Pope; Benoit Forget; Mehdi Asgari

    2008-02-01

    The sodium fast reactor is under consideration for consuming the transuranic waste in the spent nuclear fuel generated by light water reactors. This work is concerned with specialized target assemblies for an oxide-fueled sodium fast reactor that are designed exclusively for burning the americium and higher mass actinide component of light water reactor spent nuclear fuel (SNF). The associated gamma and neutron radioactivity, as well as thermal heat, associated with decay of these actinides may significantly complicate fuel handling and fabrication of recycled fast reactor fuel. The objective of using targets is to isolate in a smaller number of assemblies these concentrations of higher actinides, thus reducing the volume of fuel having more rigorous handling requirements or a more complicated fabrication process. This is in contrast to homogeneous recycle where all recycled actinides are distributed among all fuel assemblies. Several heterogeneous core geometries were evaluated to determine the fewest target assemblies required to burn these actinides without violating a set of established fuel performance criteria. The DIF3D/REBUS code from Argonne National Laboratory was used to perform the core physics and accompanying fuel cycle calculations in support of this work. Using the REBUS code, each core design was evaluated at the equilibrium cycle condition.

  20. Testing the gamma-ray burst variability/peak luminosity correlation on a Swift homogeneous sample

    E-Print Network [OSTI]

    D. Rizzuto; C. Guidorzi; P. Romano; S. Covino; S. Campana; M. Capalbi; G. Chincarini; G. Cusumano; D. Fugazza; V. Mangano; A. Moretti; M. Perri; G. Tagliaferri

    2007-04-19

    We test the gamma-ray burst correlation between temporal variability and peak luminosity of the $\\gamma$-ray profile on a homogeneous sample of 36 Swift/BAT GRBs with firm redshift determination. This is the first time that this correlation can be tested on a homogeneous data sample. The correlation is confirmed, as long as the 6 GRBs with low luminosity (tested on low-luminosity GRBs. Our results show that these GRBs are definite outliers.

  1. Simultaneous dual mode combustion engine operating on spark ignition and homogenous charge compression ignition

    DOE Patents [OSTI]

    Fiveland, Scott B.; Wiggers, Timothy E.

    2004-06-22

    An engine particularly suited to single speed operation environments, such as stationary power generators. The engine includes a plurality of combustion cylinders operable under homogenous charge compression ignition, and at least one combustion cylinder operable on spark ignition concepts. The cylinder operable on spark ignition concepts can be convertible to operate under homogenous charge compression ignition. The engine is started using the cylinders operable under spark ignition concepts.

  2. Catalyst system comprising a first catalyst system tethered to a supported catalyst

    DOE Patents [OSTI]

    Angelici, Robert J. (Ames, IA); Gao, Hanrong (Ames, IA)

    1998-08-04

    The present invention provides new catalyst formats which comprise a supported catalyst tethered to a second and different catalyst by a suitable tethering ligand. A preferred system comprises a heterogeneous supported metal catalyst tethered to a homogeneous catalyst. This combination of homogeneous and heterogeneous catalysts has a sufficient lifetime and unusually high catalytic activity in arene hydrogenations, and potentially many other reactions as well, including, but not limited to hydroformylation, hydrosilation, olefin oxidation, isomerization, hydrocyanation, olefin metathesis, olefin polymerization, carbonylation, enantioselective catalysis and photoduplication. These catalysts are easily separated from the products, and can be reused repeatedly, making these systems very economical.

  3. Catalyst system comprising a first catalyst system tethered to a supported catalyst

    DOE Patents [OSTI]

    Angelici, R.J.; Gao, H.

    1998-08-04

    The present invention provides new catalyst formats which comprise a supported catalyst tethered to a second and different catalyst by a suitable tethering ligand. A preferred system comprises a heterogeneous supported metal catalyst tethered to a homogeneous catalyst. This combination of homogeneous and heterogeneous catalysts has a sufficient lifetime and unusually high catalytic activity in arene hydrogenations, and potentially many other reactions as well, including, but not limited to hydroformylation, hydrosilication, olefin oxidation, isomerization, hydrocyanidation, olefin metathesis, olefin polymerization, carbonylation, enantioselective catalysis and photoduplication. These catalysts are easily separated from the products, and can be reused repeatedly, making these systems very economical. 2 figs.

  4. Operando X-ray absorption and EPR evidence for a single electron redox process in copper catalysis

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Lu, Qingquan; Zhang, Jian; Peng, Pan; Zhang, Guanghui; Huang, Zhiliang; Yi, Hong; Miller, Jeffrey T.; Lei, Aiwen

    2015-05-26

    An unprecedented single electron redox process in copper catalysis is confirmed using operando X-ray absorption and EPR spectroscopies. The oxidation state of the copper species in the interaction between Cu(II) and a sulfinic acid at room temperature, and the accurate characterization of the formed Cu(I) are clearly shown using operando X-ray absorption and EPR evidence. Further investigation of anion effects on Cu(II) discloses that bromine ions can dramatically increase the rate of the redox process. Moreover, it is proven that the sulfinic acids are converted into sulfonyl radicals, which can be trapped by 2-arylacrylic acids and various valuable ?-keto sulfonesmore »are synthesized with good to excellent yields under mild conditions.« less

  5. State-of-the-art in Heterogeneous Computing

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Brodtkorb, Andre R.; Dyken, Christopher; Hagen, Trond R.; Hjelmervik, Jon M.; Storaasli, Olaf O.

    2010-01-01

    Node level heterogeneous architectures have become attractive during the last decade for several reasons: compared to traditional symmetric CPUs, they offer high peak performance and are energy and/or cost efficient. With the increase of fine-grained parallelism in high-performance computing, as well as the introduction of parallelism in workstations, there is an acute need for a good overview and understanding of these architectures. We give an overview of the state-of-the-art in heterogeneous computing, focusing on three commonly found architectures: the Cell Broadband Engine Architecture, graphics processing units (GPUs), and field programmable gate arrays (FPGAs). We present a review of hardware, availablemore »software tools, and an overview of state-of-the-art techniques and algorithms. Furthermore, we present a qualitative and quantitative comparison of the architectures, and give our view on the future of heterogeneous computing.« less

  6. Sequence Heterogeneity Accelerates Protein Search for Targets on DNA

    E-Print Network [OSTI]

    Alexey A. Shvets; Anatoly B. Kolomeisky

    2015-07-21

    The process of protein search for specific binding sites on DNA is fundamentally important since it marks the beginning of all major biological processes. We present a theoretical investigation that probes the role of DNA sequence symmetry, heterogeneity and chemical composition in the protein search dynamics. Using a discrete-state stochastic approach with a first-passage events analysis, which takes into account the most relevant physical-chemical processes, a full analytical description of the search dynamics is obtained. It is found that, contrary to existing views, the protein search is generally faster on DNA with more heterogeneous sequences. In addition, the search dynamics might be affected by the chemical composition near the target site. The physical origins of these phenomena are discussed. Our results suggest that biological processes might be effectively regulated by modifying chemical composition, symmetry and heterogeneity of a genome.

  7. Point matching: A new electronic method for homogenizing the phase characteristics of giant magnetoimpedance sensors

    SciTech Connect (OSTI)

    Silva, E. Costa Gusmão, L. A. P.; Barbosa, C. R. Hall; Leipner, Y.; Fortaleza, L. G. S.; Monteiro, E. Costa

    2014-08-15

    Recently, our research group at PUC-Rio discovered that magnetic transducers based on the impedance phase characteristics of GMI sensors have the potential to multiply by one hundred the sensitivity values when compared to magnitude-based GMI transducers. Those GMI sensors can be employed in the measurement of ultra-weak magnetic fields, which intensities are even lower than the environmental magnetic noise. A traditional solution for cancelling the electromagnetic noise and interference makes use of gradiometric configurations, but the performance is strongly tied to the homogeneity of the sensing elements. This paper presents a new method that uses electronic circuits to modify the equivalent impedance of the GMI samples, aiming at homogenizing their phase characteristics and, consequently, improving the performance of gradiometric configurations based on GMI samples. It is also shown a performance comparison between this new method and another homogenization method previously developed.

  8. Homogenous charge compression ignition engine having a cylinder including a high compression space

    DOE Patents [OSTI]

    Agama, Jorge R.; Fiveland, Scott B.; Maloney, Ronald P.; Faletti, James J.; Clarke, John M.

    2003-12-30

    The present invention relates generally to the field of homogeneous charge compression engines. In these engines, fuel is injected upstream or directly into the cylinder when the power piston is relatively close to its bottom dead center position. The fuel mixes with air in the cylinder as the power piston advances to create a relatively lean homogeneous mixture that preferably ignites when the power piston is relatively close to the top dead center position. However, if the ignition event occurs either earlier or later than desired, lowered performance, engine misfire, or even engine damage, can result. Thus, the present invention divides the homogeneous charge between a controlled volume higher compression space and a lower compression space to better control the start of ignition.

  9. Massive star evolution in close binaries:conditions for homogeneous chemical evolution

    E-Print Network [OSTI]

    Song, H F; Maeder, A; Ekstrom, S; Eggenberger, P

    2015-01-01

    We investigate the impact of tidal interactions, before any mass transfer, on various properties of the stellar models. We study the conditions for obtaining homogeneous evolution triggered by tidal interactions, and for avoiding any Roche lobe overflow during the Main-Sequence phase. We consider the case of rotating stars computed with a strong coupling mediated by an interior magnetic field. In models without any tidal interaction (single stars and wide binaries), homogeneous evolution in solid body rotating models is obtained when two conditions are realized: the initial rotation must be high enough, the loss of angular momentum by stellar winds should be modest. This last point favors metal-poor fast rotating stars. In models with tidal interactions, homogeneous evolution is obtained when rotation imposed by synchronization is high enough (typically a time-averaged surface velocities during the Main-Sequence phase above 250 km s$^{-1}$), whatever the mass losses. In close binaries, mixing is stronger at h...

  10. Testing the homogeneity of the Universe using gamma-ray bursts

    E-Print Network [OSTI]

    Li, Ming-Hua

    2015-01-01

    In this paper, we study the homogeneity of the GRB distribution using a subsample of the Greiner GRB catalogue, which contains 314 objects with redshift $0Gamma-Ray Burst Host Galaxy Legacy Survey (SHOALS). The real space two-point correlation function (2PCF) of GRBs, $\\xi(r),$ is calculated using a Landy-Szalay estimator. We perform a standard least-$\\chi^2$ fit to the measured 2PCFs of GRBs. We use the best-fit 2PCF to deduce a recently defined homogeneity scale. The homogeneity scale, $R_H$, is defined as the comoving radius of the sphere inside which the number of GRBs $N(

  11. Viscosity method for Homogenization of Parabolic Nonlinear Equations in Perforated Domains

    E-Print Network [OSTI]

    Kim, Sunghoon

    2011-01-01

    In this paper, we develop a viscosity method for Homogenization of Nonlinear Parabolic Equations constrained by highly oscillating obstacles or Dirichlet data in perforated domains. The Dirichlet data on the perforated domain can be considered as a constraint or an obstacle. Homogenization of nonlinear eigen value problems has been also considered to control the degeneracy of the Porous medium equation in perforated domains. For the simplicity, we consider obstacles that consist of cylindrical columns distributed periodically and perforated domains with punctured balls. If the decay rate of the capac- ity of columns or the capacity of punctured ball is too high or too small, the limit of u\\k{o} will converge to trivial solutions. The critical decay rates of having nontrivial solution are obtained with the construction of barriers. We also show the limit of u\\k{o} satisfies a homogenized equation with a term showing the effect of the highly oscillating obstacles or perforated domain in viscosity sense.

  12. Two stroke homogenous charge compression ignition engine with pulsed air supplier

    DOE Patents [OSTI]

    Clarke, John M. (Chillicothe, IL)

    2003-08-05

    A two stroke homogenous charge compression ignition engine includes a volume pulsed air supplier, such as a piston driven pump, for efficient scavenging. The usage of a homogenous charge tends to decrease emissions. The use of a volume pulsed air supplier in conjunction with conventional poppet type intake and exhaust valves results in a relatively efficient scavenging mode for the engine. The engine preferably includes features that permit valving event timing, air pulse event timing and injection event timing to be varied relative to engine crankshaft angle. The principle use of the invention lies in improving diesel engines.

  13. Efficient excitation and tuning of toroidal dipoles within individual homogenous nanoparticles

    E-Print Network [OSTI]

    Liu, Wei; Lei, Bing; Hu, Haojun; Miroshnichenko, Andrey E

    2015-01-01

    We revisit the fundamental topic of light scattering by single homogenous nanoparticles from the new perspective of excitation and manipulation of toroidal dipoles. It is revealed that besides within all-dielectric particles, toroidal dipoles can also be efficiently excited within homogenous metallic nanoparticles. Moreover, we show that those toroidal dipoles excited can be spectrally tuned through adjusting the radial anisotropy parameters of the materials, which paves the way for further more flexible manipulations of the toroidal responses within photonic systems. The study into toroidal multipole excitation and tuning within nanoparticles deepens our understanding of the seminal problem of light scattering, and may incubate many scattering related fundamental researches and applications.

  14. Enhancement of crystal homogeneity of protein crystals under application of an external alternating current electric field

    SciTech Connect (OSTI)

    Koizumi, H.; Uda, S.; Fujiwara, K.; Nozawa, J.; Tachibana, M.; Kojima, K.

    2014-10-06

    X-ray diffraction rocking-curve measurements were performed on tetragonal hen egg white (HEW) lysozyme crystals grown with and without the application of an external alternating current (AC) electric field. The crystal quality was assessed by the full width at half maximum (FWHM) value for each rocking curve. For two-dimensional maps of the FWHMs measured on the 440 and the 12 12 0 reflection, the crystal homogeneity was improved under application of an external electric field at 1 MHz, compared with that without. In particular, the significant improvement of the crystal homogeneity was observed for the 12 12 0 reflection.

  15. Future geodesic completeness of some spatially homogeneous solutions of the vacuum Einstein equations in higher dimensions

    E-Print Network [OSTI]

    Arne Goedeke; Alan D. Rendall

    2010-02-21

    It is known that all spatially homogeneous solutions of the vacuum Einstein equations in four dimensions which exist for an infinite proper time towards the future are future geodesically complete. This paper investigates whether the analogous statement holds in higher dimensions. A positive answer to this question is obtained for a large class of models which can be studied with the help of Kaluza-Klein reduction to solutions of the Einstein-scalar field equations in four dimensions. The proof of this result makes use of a criterion for geodesic completeness which is applicable to more general spatially homogeneous models.

  16. Homogenization and norm resolvent convergence for elliptic operators in a strip perforated along a curve

    E-Print Network [OSTI]

    Denis Borisov; Giuseppe Cardone; Tiziana Durante

    2015-03-21

    We consider an infinite planar straight strip perforated by small holes along a curve. In such domain, we consider a general second order elliptic operator subject to classical boundary conditions on the holes. Assuming that the perforation is non-periodic and satisfies rather weak assumptions, we describe all possible homogenized problems. Our main result is the norm resolvent convergence of the perturbed operator to a homogenized one in various operator norms and the estimates for the rate of convergence. On the basis of the norm resolvent convergence, we prove the convergence of the spectrum.

  17. PerCon: A Personal Digital Library for Heterogeneous Data

    E-Print Network [OSTI]

    Shipman, Frank

    PerCon: A Personal Digital Library for Heterogeneous Data Su Inn Park, Frank Shipman Center for the Study of Digital Libraries Department of Computer Science and Engineering Texas A&M University 1 a personal digital library of data. Users may then search, browse, visualize and annotate the data

  18. Probabilistic Detection of Mobile Targets in Heterogeneous Sensor Networks

    E-Print Network [OSTI]

    Poovendran, Radha

    , a surveillance system can be realized via fusion of data aggregated from various sensor modalities: infrared, CCD of detection can be quantified by evaluating the probability of detection by at least k sensors, where kProbabilistic Detection of Mobile Targets in Heterogeneous Sensor Networks Loukas Lazos Network

  19. Design of heterogeneous turbine blade Xiaoping Qian, Deba Dutta*

    E-Print Network [OSTI]

    Qian, Xiaoping

    Design of heterogeneous turbine blade Xiaoping Qian, Deba Dutta* Department of Mechanical material. A critical task of such synthesis in turbine blade design is an effective design method approach for turbine blade design, which ties B-spline representation of a turbine blade to a physics

  20. Lighting the Dark Silicon by Exploiting Heterogeneity on Future Processors

    E-Print Network [OSTI]

    Koppelman, David M.

    ][17], leading to an ever increasing power density on modern processors. On the other hand, the max- imumLighting the Dark Silicon by Exploiting Heterogeneity on Future Processors Ying Zhang Lu Peng Xin processor power consumption should be always enclosed within a reasonable envelope despite the manufacturing

  1. Scale-dependent seismic velocity in heterogeneous media

    SciTech Connect (OSTI)

    Mukerji, T.; Mavko, G.; Mujica, D. [Stanford Univ., CA (United States)] [Stanford Univ., CA (United States); Lucet, N. [IFP, Rueil-Malmaison (France)] [IFP, Rueil-Malmaison (France)

    1995-07-01

    The measurable traveltime of seismic events propagating in heterogeneous media depend on the geologic scale, the seismic wavelength, and the propagation distance. In general, the velocity inferred from arrival times is slower when the wavelength is longer than the scale of heterogeneity and faster when the wavelength is shorter. For normal incidence propagation in stratified media, this is the difference between averaging elastic compliance sin the long wavelength limit. In two and three dimensions there is also the path effect. Shorter wavelengths tend to find faster paths, thus biasing the traveltimes to lower values. In the shorter wavelength limit, the slowness inferred from the average traveltime is smaller than the mean slowness of the medium. When the propagation distance is much larger than the scale of the heterogeneity, the path effect causes the velocity increase from long to short wavelengths to be much larger in two dimensions than in one dimension, and even larger in three dimensions. The amount of velocity dispersion can be understood theoretically, but there is some discrepancy between theory and experiment as to what ratio of wavelength to heterogeneity scale separates the long and short wavelength limits. The scale-dependent traveltime implies that a measured velocity depends not just on rock properties, but also on the scale of the measurement relative to he scale of the geology.

  2. HETEROGENEOUS PROCESS MIGRATION SCALABLE NETWORK OF WORKSTATIONS (SNOW)

    E-Print Network [OSTI]

    Sun, Xian-He

    HETEROGENEOUS PROCESS MIGRATION for SCALABLE NETWORK OF WORKSTATIONS (SNOW) Xian-He Sun Department of Computer Science Louisiana State University sun@bit.csc.lsu.edu URL: http://www.csc.lsu.edu/ scs/SNOW/ Nov and restoration mechanism The SNOW/MpPVM Software Environment Components and Implementation Issues Experimental

  3. Colorado Plateau magmatism and uplift by warming of heterogeneous lithosphere

    E-Print Network [OSTI]

    Pederson, Joel L.

    LETTERS Colorado Plateau magmatism and uplift by warming of heterogeneous lithosphere Mousumi Roy1 , Thomas H. Jordan2 & Joel Pederson3 The forces that drove rock uplift of the low-relief, high experienced 2 km of rock uplift7 without significant internal deformation2­4 . Here we propose that warming

  4. Alamo: An Architecture for Integrating Heterogeneous Data Sources \\Lambda

    E-Print Network [OSTI]

    Samoladas, Vasilis

    Alamo: An Architecture for Integrating Heterogeneous Data Sources \\Lambda Daniel P. Miranker an architecture, Alamo, that addresses both the semantic and physi­ cal aspects of data integration. The Alamo ar source, the Alamo architecture forms an infrastructure for the development and possi­ ble integration

  5. Fog Water and Ecosystem Function: Heterogeneity in a California

    E-Print Network [OSTI]

    Templer, Pamela

    Fog Water and Ecosystem Function: Heterogeneity in a California Redwood Forest Holly A. Ewing,1 Biology, University of Connecticut, 75 N. Eagleville Road, Storrs, Connecticut 06269, USA ABSTRACT Fog and nitrogen (N) fluxes from hori- zontally moving fog and vertically delivered rain as well as redwood tree

  6. Utility Functions and Resource Management in an Oversubscribed Heterogeneous

    E-Print Network [OSTI]

    Maciejewski, Anthony A. "Tony"

    IEEEProof Utility Functions and Resource Management in an Oversubscribed Heterogeneous Computing on those being investigated by the Extreme Scale Systems Center at Oak Ridge National Laboratory. Utility a metric for the performance of resource allocation heuristics. Each task has a time-varying utility

  7. TURBULENT SHEAR STRESS IN HETEROGENEOUS SEDIMENT-LADEN FLOWS

    E-Print Network [OSTI]

    Julien, Pierre Y.

    TURBULENT SHEAR STRESS IN HETEROGENEOUS SEDIMENT-LADEN FLOWS By Hyoseop Woo,1 Associate Member are the beginning of motion of sediment particles and sediment transport in alluvial channels. If shear stress can be well defined in clear-water flows, compar- atively little is known about shear stresses in sediment

  8. Optimal Power Control in Rayleigh-fading Heterogeneous Networks

    E-Print Network [OSTI]

    Tan, Chee Wei

    specifi- cation in a heterogeneous network to minimize the total energy consumption and simultaneously fading. As a by-product, we solve an open problem of convergence for a previously proposed algorithm threshold that is often com- puted from the quality of service requirement. The statistics of the SINR

  9. Continuation Methods for Mixing Heterogeneous Sources Adrian Corduneanu

    E-Print Network [OSTI]

    Jaakkola, Tommi S.

    tasks involve esti­ mation from heterogeneous information sources. This includes classification a preferred information source with another in this setting by evolving continuous paths of fixed points important learning problems involve a compromise between competing sources of information. For example

  10. Energy Consumption Characteriation of Heterogeneous Servers School of Computer Science

    E-Print Network [OSTI]

    Qin, Xiao

    Energy Consumption Characteriation of Heterogeneous Servers Xiao Zhang School of Computer Science Machine between servers to save energy. An accurate energy consumption model is the basic of energy management. Most past studies show that energy consumption has linear relation with resource utilization. We

  11. Modeling mesoscopic attenuation in a highly heterogeneous Biot's medium

    E-Print Network [OSTI]

    Santos, Juan

    and dispersion at seismic frequencies is known as mesoscopic loss, and is caused by the presence-wave diffusion process. It is also the case that the exact spatial distribution of these heterogeneities the effect of underground carbon dioxide (CO2) accumulations on the amplitude and attenuation of seismic

  12. Data Collection and Restoration for Heterogeneous Process Migration *

    E-Print Network [OSTI]

    Sun, Xian-He

    Data Collection and Restoration for Heterogeneous Process Migration * Kasidit Chanchio Xian-He Sun,sung@cs.iit.edu Abstract This study presents a practical solution for data collec- tion and restoration to migrate- grams. Experimental and analytical results show that (1) a user-level process can be migrated across

  13. Practical Experience in the Numerical Dangers of Heterogeneous Computing

    E-Print Network [OSTI]

    Dongarra, Jack

    in writing reliable numerical library software for heterogeneous computing environments. Although a lot ways to avoid potential pitfalls, or if that is not possible, we recommend that the software;1. INTRODUCTION There are special challenges associated with writing reliable numerical software on networks

  14. Hybrid Heterogeneous Energy Supply Networks Farinaz Koushanfar and Azalia Mirhoseini

    E-Print Network [OSTI]

    Hybrid Heterogeneous Energy Supply Networks Farinaz Koushanfar and Azalia Mirhoseini Department--Efficient energy supply, storage, and distribution are key technical challenges for design and operation of electronic systems. In particular, energy supply is the most scarce resource and constraint for mobile

  15. Graph-based Navigation Strategies for Heterogeneous Spatial Data Sets

    E-Print Network [OSTI]

    Rodríguez-Tastets, Maria Andrea

    Graph-based Navigation Strategies for Heterogeneous Spatial Data Sets Andrea Rodr´iguez1 the information contribution of data sets based on correspondence relations outperform a strategy that considers- base representation, this work describes strategies that optimize the navigation of data sets

  16. An analysis and hypothesis generation platform for heterogeneous cancer

    E-Print Network [OSTI]

    Reed, Chris

    An analysis and hypothesis generation platform for heterogeneous cancer databases. Philip Roy QUINLAN a,1, Alastair THOMPSON a and Chris REED b a Dundee Cancer Centre, University of Dundee, Ninewells Hospital, Dundee b School of Computing, University of Dundee, Dundee Abstract. The field of cancer research

  17. Automatic Intra-Application Load Balancing for Heterogeneous Systems

    E-Print Network [OSTI]

    Huang, Wei

    Automatic Intra-Application Load Balancing for Heterogeneous Systems Michael Boyer, Shuai Che AMD #12;2 | Automatic Intra-Application Load Balancing | June 14, 2011 Motivation Many applications;3 | Automatic Intra-Application Load Balancing | June 14, 2011 Leveraging Multiple Devices Writing correct

  18. Establishment Heterogeneity, Exporter Dynamics, and the Effects of Trade Liberalization

    E-Print Network [OSTI]

    Alexandrova, Ivana

    to free trade equivalent to 1.03 percent of steady state consumption. Con- sidering the transitionEstablishment Heterogeneity, Exporter Dynamics, and the Effects of Trade Liberalization George the effect of reducing tariffs on welfare, trade, and export participation. We find sizeable gains to moving

  19. Distributed, Secure Load Balancing with Skew, Heterogeneity, and Churn

    E-Print Network [OSTI]

    Distributed, Secure Load Balancing with Skew, Heterogeneity, and Churn Jonathan Ledlie and Margo rates of node join and leave (churn), and wide variation in node network and storage capacity be heavy-tailed, and because node availability and churn rates may change over time. Learning to adapt

  20. A Heterogeneous Animated Platform for Educational Participatory Simulations

    E-Print Network [OSTI]

    Tomlinson, Bill

    by populations of 3D animated virtual creatures. When a human participant brings one of the mobile devices (a as an educational tool. Keywords: Human-Computer Interaction, Handheld/Mobile Devices, Virtual/3D EnvironmentsA Heterogeneous Animated Platform for Educational Participatory Simulations Bill Tomlinson ACE

  1. An Argument for Archiving Facebook as a Heterogeneous Personal Store

    E-Print Network [OSTI]

    Marshall, Cathy

    An Argument for Archiving Facebook as a Heterogeneous Personal Store Catherine C. Marshall not archive the contents of a major social media service like Facebook to ensure the permanence to archive social media: Facebook is not only viewed as private and vulnerable to violations of content

  2. a Modular, Multi-Engine Simulator for Heterogeneous Swarm Robotics

    E-Print Network [OSTI]

    Libre de Bruxelles, Université

    ARGoS: a Modular, Multi-Engine Simulator for Heterogeneous Swarm Robotics Carlo Pinciroli, Vito, Gianni Di Caro, Frederick Ducatelle, Timothy Stirling§, ´Alvaro Guti´errez, Luca Maria Gambardella. A unique feature of ARGoS is the possibility to use multiple physics engines of different types

  3. Energy Conservation in Heterogeneous Server Clusters Taliver Heath

    E-Print Network [OSTI]

    Bianchini, Ricardo

    Energy Conservation in Heterogeneous Server Clusters Taliver Heath ¡ , Bruno Diniz ¢ , Enrique V of Quito Piscataway, NJ 08854-8019 Belo Horizonte, Brazil Quito, Ecuador¤ taliver,ricardob¥ @cs nodes show that our server can consume 42% less energy than an energy-oblivious server, with only

  4. Numerical assessment of 3-D macrodispersion in heterogeneous porous media

    E-Print Network [OSTI]

    Paris-Sud XI, Université de

    . [1] Hydrodynamic dispersion is a key controlling factor of solute transport in heterogeneous porous.20206. 1. Introduction [2] Hydrodynamic dispersion is a major component of solute transport; Freeze, 1975; Gelhar and Axness, 1983]. The logarithm of permeability Y xð Þ ¼ ln K xð Þð Þ follows

  5. ADAPTIVE ONLINE ENERGY SAVING FOR HETEROGENEOUS SENSOR Meikang Qiu1

    E-Print Network [OSTI]

    Sha, Edwin

    ADAPTIVE ONLINE ENERGY SAVING FOR HETEROGENEOUS SENSOR NETWORKS Meikang Qiu1 Jingtong Hu2 Edwin H-to-predict environments and have limited lifetime. We use a novel adaptive online energy saving (AOES) algorithm to save as a probabilistic random variable to save energy by se- lecting the best mode assignment for each node, which

  6. Monitoring Marine Environments using a Team of Heterogeneous Robots

    E-Print Network [OSTI]

    Dudek, Gregory

    1 Monitoring Marine Environments using a Team of Heterogeneous Robots Yogesh Girdhar1, Anqi Xu1, Gregory Dudek1 Abstract--We present a novel approach for monitoring marine environments by a team supervisor to plan for further exploration. I. INTRODUCTION Monitoring marine environments is a challenging

  7. Examining Energy Use in Heterogeneous Archival Storage Systems

    E-Print Network [OSTI]

    Polyzotis, Neoklis (Alkis)

    Examining Energy Use in Heterogeneous Archival Storage Systems Ian F. Adams*, Ethan L. Miller to consume upwards of 35% the total energy used [2]. As systems grow to encompass thousands of storage to power and cool storage devices, and energy costs are no longer the only issues--data center architects

  8. AVERAGE INFLUENCE OF THRESHOLD BOOLEAN FUNCTIONS AND HETEROGENEOUS KAUFFMAN NETWORKS

    E-Print Network [OSTI]

    Matache, Dora

    was to build upon previous research about other types of func- tions and their influence by developing a model it to model the influence and find the critical values for combinations of different types of Boolean recent research has focused on finding phase transitions for homogeneous network ensembles with just one

  9. Slow Crack Propagation in Heterogeneous Materials J. Kierfeld1

    E-Print Network [OSTI]

    Kierfeld, Jan

    explained by Griffith [2]--while homogeneously amorphous systems exhibit slow ductile fracture controlled, whether frozen defects enhance or degrade the fracture toughness of a material. The inspiring work [5 materials with frozen defects contain a large number of arrested microcracks and that their fracture

  10. Oxygenates from synthesis gas

    SciTech Connect (OSTI)

    Falter, W.; Keim, W.

    1994-12-31

    The direct synthesis of oxygenates starting from synthesis gas is feasible by homogeneous and heterogeneous catalysis. Homogeneous Rh and Ru based catalysts yielding methyl formate and alcohols will be presented. Interestingly, modified heterogeneous catalysts based on {open_quotes}Isobutyl Oel{close_quotes} catalysis, practized in Germany (BRD) up to 1952 and in the former DDR until recently, yield isobutanol in addition to methanol. These {open_quotes}Isobutyl Oel{close_quotes} catalysts are obtained by adding a base such as Li < Na < K < Cs to a Zn-Cr{sub 2}O{sub 3} methanol catalyst. Isobutanol is obtained in up to 15% yield. Our best catalyst a Zr-Zn-Mn-Li-Pd catalyst produced isobotanol up to 60% at a rate of 740g isobutanol per liter catalyst and hour.

  11. Influence of heterogeneity on second-kind self-similar solutions...

    Office of Scientific and Technical Information (OSTI)

    Influence of heterogeneity on second-kind self-similar solutions for viscous gravity currents Citation Details In-Document Search Title: Influence of heterogeneity on second-kind...

  12. A theoretical and empirical exploration into the heterogeneous fragility of Chilean firms and workplaces

    E-Print Network [OSTI]

    Landerretche, Oscar

    2006-01-01

    This dissertation consists of three essays on the heterogeneous reactions of firms to shocks, with particular empirical applications to the Chilean economy. The first essay presents a model of heterogeneity in an economy ...

  13. Enhancing marketing with engineering: Optimal product line design for heterogeneous markets

    E-Print Network [OSTI]

    Papalambros, Panos

    Enhancing marketing with engineering: Optimal product line design for heterogeneous markets Jeremy design and development often require a balance of technical and market tradeoffs. Quantitative methods: John H. Roberts Keywords: Product line design Heterogeneity Decomposition Analytical target cascading

  14. ENHANCING MARKETING WITH ENGINEERING: OPTIMAL PRODUCT LINE DESIGN FOR HETEROGENEOUS MARKETS

    E-Print Network [OSTI]

    Papalambros, Panos

    ENHANCING MARKETING WITH ENGINEERING: OPTIMAL PRODUCT LINE DESIGN FOR HETEROGENEOUS MARKETS Jeremy of Business. #12;- 1 - ENHANCING MARKETING WITH ENGINEERING: OPTIMAL PRODUCT LINE DESIGN FOR HETEROGENEOUS MARKETS ABSTRACT Successful product line design and development often requires balancing technical

  15. Environmental Kuznets Curve for carbon dioxide emissions: lack of robustness to heterogeneity?

    E-Print Network [OSTI]

    Paris-Sud XI, Université de

    1 Environmental Kuznets Curve for carbon dioxide emissions: lack of robustness to heterogeneity applying the iterative Bayesian shrinkage procedure. The environmental Kuznets curve (EKC) hypothesis. Keywords: Environmental Kuznets curve; Bayesian shrinkage estimator; Heterogeneity JEL classification: O13

  16. Energy-Efficient Scheduling for Parallel Applications Running on Heterogeneous Clusters

    E-Print Network [OSTI]

    Qin, Xiao

    ), energy efficiency, and heterogeneities. Basically, processors, networks, disks, and cooling system1 Energy-Efficient Scheduling for Parallel Applications Running on Heterogeneous Clusters Ziliang 39406 mnijim@usm.edu § Department of Computer Science New Mexico Institute of Mining and Technology

  17. An Integrated Hardware-Software CosimulationEnvironment for Heterogeneous SystemsPrototyping

    E-Print Network [OSTI]

    Ha, Soonhoi

    An Integrated Hardware-Software CosimulationEnvironment for Heterogeneous Systems - In this paper, we present a hardware-software cosimulation environment for heterogeneoussystems of heterogeneous systems whose hardware and software components are interacting. Traditionally, the task has been

  18. RESEARCH ARTICLE Spatial spread of an alien tree species in a heterogeneous

    E-Print Network [OSTI]

    Petite, Samuel

    RESEARCH ARTICLE Spatial spread of an alien tree species in a heterogeneous forest landscape the observed invasion patterns of an alien tree species, Prunus serotina Ehrh., in a heterogeneous managed

  19. Micronesica 39(2): 297-314, 2007 Habitat Heterogeneity of Cycas micronesica Seed Chemistry

    E-Print Network [OSTI]

    Marler, Thomas E.

    to respond to environmental heterogeneity with phenotypic plasticity of secondary chemistry (Brenes- Arguedas & Coley 2005, Callaway et al. 2003). Phenotypic plasticity resulting from plant ontogeny and heterogeneous gametophyte toxins and determined that the most noxious in relation to neur

  20. Homogenization of a spectral equation with drift in linear Guillaume Bal

    E-Print Network [OSTI]

    Bal, Guillaume

    theory posed in a periodic heterogeneous domain. This equation models the stability of nuclear reactor Introduction The power distribution in a nuclear reactor is determined by solving a linear transport spectral in radiative transfer theory, which models the propagation of acoustic, electromagnetic, or elastic waves

  1. Synthesis of nanoscale particles of Ta and Nb3Al by homogeneous reduction in liquid ammonia

    E-Print Network [OSTI]

    Sadoway, Donald Robert

    and electronic). This prediction was confirmed by reacting TaCl5 with sodium, each dissolved in liquid ammonia, potassium heptafluorotantalate (K2TaF7) and sodium are both added to a halide melt (known as a "diluent growth. The fact that sodium is immiscible in the molten salt diluent promotes heterogeneous nucleation

  2. CATALYSIS SCIENCE INITIATIVE: From First Principles Design to Realization of Bimetallic Catalysts for Enhanced Selectivity

    SciTech Connect (OSTI)

    MAVRIKAKIS, MANOS DUMESIC, JAMES A.

    2007-05-03

    In this project, we have integrated state-of-the-art Density Functional Theory (DFT) models of heterogeneous catalytic processes with high-throughput screening of bimetallic catalytic candidates for important industrial problems. We have studied a new class of alloys characterized by a surface composition different from the bulk composition, and investigated their stability and activity for the water-gas shift reaction and the oxygen reduction reaction. The former reaction is an essential part of hydrogen production; the latter is the rate-limiting step in low temperature H2 fuel cells. We have identified alloys that have remarkable stability and activity, while having a much lower material cost for both of these reactions. Using this knowledge of bimetallic interactions, we have also made progress in the industrially relevant areas of carbohydrate reforming and conversion of biomass to liquid alkanes. One aspect of this work is the conversion of glycerol (a byproduct of biodiesel production) to synthesis gas. We have developed a bifunctional supported Pt catalyst that can cleave the carbon-carbon bond while also performing the water-gas shift reaction, which allows us to better control the H2:CO ratio. Knowledge gained from the theoretical metal-metal interactions was used to develop bimetallic catalysts that perform this reaction at low temperature, allowing for an efficient coupling of this endothermic reaction with other reactions, such as Fischer-Tropsch or methanol synthesis. In our work on liquid alkane production from biomass, we have studied deactivation and selectivity in these areas as a function of metal-support interactions and reaction conditions, with an emphasis on the bifunctionality of the catalysts studied. We have identified a stable, active catalyst for this process, where the selectivity and yield can be controlled by the reaction conditions. While complete rational design of catalysts is still elusive, this work demonstrates the power of combining the insights gained from theoretical models and the work of experiments to develop new catalysts for current and future industrial challenges.

  3. Deep Hydrodesulfurization in Homogeneous Solution: Access to a Transition-Metal Insertion Complex of

    E-Print Network [OSTI]

    Jones, William D.

    Deep Hydrodesulfurization in Homogeneous Solution: Access to a Transition-Metal Insertion Complex has been focused on the problems of "deep" hydrodesulfurization (HDS) or production of gas oils is to find more active catalysts for deep HDS, and this challenge can be stated without much

  4. Optimization of the structural Gabor functions in a homogeneous velocity model

    E-Print Network [OSTI]

    Cerveny, Vlastislav

    Optimization of the structural Gabor functions in a homogeneous velocity model for a zero-o#11;set functions should be optimized, and the Gabor functions should form a frame. We present a simple attempt functions and the space{wavenumber lattice of their central points are optimized analytically

  5. RATE OF STRAIN TENSOR STATISTICS IN COMPRESSIBLE HOMOGENEOUS G. Erlebacher 1 , S. Sarkar 1

    E-Print Network [OSTI]

    Erlebacher, Gordon

    RATE OF STRAIN TENSOR STATISTICS IN COMPRESSIBLE HOMOGENEOUS TURBULENCE G. Erlebacher 1 , S. Sarkar examined to determine the effect of compressibility on the growth of kinetic energy and of dissipation Mach number) decrease the growth rate of the kinetic energy. This reduction in the growth rate

  6. Homogeneous Decomposition Mechanisms of Diethylzinc by Raman Spectroscopy and Quantum Chemical Calculations

    E-Print Network [OSTI]

    Anderson, Timothy J.

    *, Department of Chemical Engineering and Department of Chemistry, UniVersity of Florida, GainesVille, Florida for decomposition by -hydride elimination. The results suggest that -hydride elimination is a minor pathway for the gas-phase homogeneous pyrolysis of diethylzinc. A reasonable transition state during -hydride

  7. Hydrodesulfurization of Thiophene and Benzothiophene to Butane and Ethylbenzene by a Homogeneous Iridium

    E-Print Network [OSTI]

    Jones, William D.

    Hydrodesulfurization of Thiophene and Benzothiophene to Butane and Ethylbenzene by a Homogeneous, in high yields. Upon further thermolysis under H2, the completely desulfurized products, butane examples of complete desulfur- ization to butanes, butenes, or metal alkyls have been reported.4

  8. Modelling by homogenization of the long term rock dissolution and geomechanical effects

    E-Print Network [OSTI]

    Boyer, Edmond

    1 Modelling by homogenization of the long term rock dissolution and geomechanical effects Jolanta modifications of the hydrodynamical as well as geomechanical properties of the reservoir. The long-term safety the modelling of long term geomechanical effects related to CO2 storage are proposed. Of special interest

  9. Kinetics of the Homogeneous Catalytic Hydrogenation of Olefins in Supercritical Carbon Dioxide Using a Fluoroacrylate Copolymer

    E-Print Network [OSTI]

    Abdou, Hanan E.

    Kinetics of the Homogeneous Catalytic Hydrogenation of Olefins in Supercritical Carbon Dioxide a fluoroacrylate copolymer grafted rhodium catalyst in supercritical carbon dioxide (scCO2) are reported field of chemical reaction engineering.3-8 Specifically, supercritical carbon dioxide (scCO2

  10. An adiabatic homogeneous model for the flow around a multi-perforated plate

    E-Print Network [OSTI]

    Mendez, Simon

    homogeneous model to account for multi-perforated lin- ers in combustion chamber flow simulations is described in industrial full-scale computations of gas turbine combustion chambers, where effusion cooling is commonly in the streamwise direction Post-doctoral fellow, CFD team, mendez@cerfacs.fr, AIAA Member Professor, I3M CNRS UMR

  11. Capacity Bounds for Energy Efficient Data Streaming in Homogeneous Wireless Ad Hoc Networks

    E-Print Network [OSTI]

    Li, Zongpeng

    Capacity Bounds for Energy Efficient Data Streaming in Homogeneous Wireless Ad Hoc Networks Hanan activation schemes with provable asymptotic bounds on the capacity and energy efficiency of the induced add to the noise levels of each other and cause the overall network capacity to decrease

  12. A HOMOGENIZATION TECHNIQUE FOR THE BOLTZMANN EQUATION FOR LOW PRESSURE CHEMICAL VAPOR DEPOSITION 1

    E-Print Network [OSTI]

    Markowich, Peter A.

    A HOMOGENIZATION TECHNIQUE FOR THE BOLTZMANN EQUATION FOR LOW PRESSURE CHEMICAL VAPOR DEPOSITION 1 the approach. The setup models low pressure chemical vapor deposition processes in the manufacturing. Low pressure chemical vapor deposition is used in the manufactur- ing of integrated circuits

  13. Invariance and homogenization of an adaptive time gap car-following model

    E-Print Network [OSTI]

    Monneau, Régis

    Invariance and homogenization of an adaptive time gap car-following model R. Monneau , M called the adaptive time gap car- following model. This is a system of ODEs which describes the interactions between cars moving on a single line. The time gap is the time that a car needs to reach

  14. DOI: 10.1002/cssc.201000142 Homogeneous Oxidation Reactions of Propanediols at Low

    E-Print Network [OSTI]

    Iglesia, Enrique

    con- version attractive. Glycerol can be converted into 1,3-propane- diol by either enzymatic selectivity in homogeneous 1,3-propane- diol oxidation led us to introduce the acrolein and H2O formed of Chemical Engineering, University of California at Berkeley Berkeley, CA 94720 (USA) Fax: (+1)510-642-4778 E

  15. ELECTRICAL IMPEDANCE MAMMOGRAPHY Forward problem for homogeneous and 3-D sphere

    E-Print Network [OSTI]

    Cerveny, Vlastislav

    ELECTRICAL IMPEDANCE MAMMOGRAPHY Forward problem for homogeneous and 3-D sphere Jakub Vel Prague, October 15, 2014 J. Vel´imsk´y (CUP) Electrical Impedance Mammography Prague, 15.10.2014 1 / 26 and SH-FE discretization Remarks on the inverse problem Current status J. Vel´imsk´y (CUP) Electrical

  16. Coincident-Frequency Entangled Photons in a Homogenous Gravitational Field - A Thought Experiment

    E-Print Network [OSTI]

    Clovis Jacinto de Matos

    2010-11-24

    Assuming that the Principle of energy conservation holds for coincident-frequency entangled photons propagating in a homogeneous gravitational field. It is argued that in this physical context, either Quantum entanglement or the weak equivalence principle are broken by the photons.

  17. The Condensate Equation for non-homogeneous Andre F. Verbeure1

    E-Print Network [OSTI]

    The Condensate Equation for non-homogeneous Bosons Andr´e F. Verbeure1 Institute for Theoretical)-condensation. This phe- nomenon is accompanied with spontaneous breaking of the translation symmetry down of the condensate equation for these systems. We discuss model applications. KEY WORDS: Bose- Einstein condensation

  18. Increasing homogeneity in global food supplies and the implications for food security

    E-Print Network [OSTI]

    Rieseberg, Loren

    Increasing homogeneity in global food supplies and the implications for food security Colin K Trust, 53115 Bonn, Germany; g CGIAR Research Program on Climate Change, Agriculture, and Food Security to the world's food supplies has been considered a potential threat to food security. However, changes

  19. Homogenization induced by chaotic mixing and diffusion in an oscillatory chemical reaction I. Z. Kiss,1,

    E-Print Network [OSTI]

    Kiss, Istvan Zoltan

    Homogenization induced by chaotic mixing and diffusion in an oscillatory chemical reaction I. Z dynamics corresponding to an oscillatory chemical reaction coupled with diffusion and chaotic advection as a synchronization of these local oscillators. The specific chemical reaction that we consider is the chlorine

  20. Statistical fracture modeling: crack path and fracture criteria with application to homogeneous and

    E-Print Network [OSTI]

    Ritchie, Robert

    Statistical fracture modeling: crack path and fracture criteria with application to homogeneous; accepted 23 January 2002 Abstract Analysis has been performed on fracture initiation near a crack in a brittle material with strength described by Weibull statistics. This nonlocal fracture model allows