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1

Converting Homogeneous to Heterogeneous in Electrophilic Catalysis using Monodisperse Metal Nanoparticles  

SciTech Connect (OSTI)

A continuing goal in catalysis is the transformation of processes from homogeneous to heterogeneous. To this end, nanoparticles represent a new frontier in heterogeneous catalysis, where this conversion is supplemented by the ability to obtain new or divergent reactivity and selectivity. We report a novel method for applying heterogeneous catalysts to known homogeneous catalytic reactions through the design and synthesis of electrophilic platinum nanoparticles. These nanoparticles are selectively oxidized by the hypervalent iodine species PhICl{sub 2}, and catalyze a range of {pi}-bond activation reactions previously only homogeneously catalyzed. Multiple experimental methods are utilized to unambiguously verify the heterogeneity of the catalytic process. The discovery of treatments for nanoparticles that induce the desired homogeneous catalytic activity should lead to the further development of reactions previously inaccessible in heterogeneous catalysis. Furthermore, our size and capping agent study revealed that Pt PAMAM dendrimer-capped nanoparticles demonstrate superior activity and recyclability compared to larger, polymer-capped analogues.

Witham, Cole A.; Huang, Wenyu; Tsung, Chia-Kuang; Kuhn, John N.; Somorjai, Gabor A.; Toste, F. Dean

2009-10-15T23:59:59.000Z

2

ISHHC XIII International Symposium on the Relations betweenHomogeneous and Heterogeneous Catalysis  

SciTech Connect (OSTI)

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.

Somorjai (Ed.), G.A.

2007-06-11T23:59:59.000Z

3

The 13th International Symposium on Relations between Homogeneous and Heterogeneous Catalysis -- AnIntroduction  

SciTech Connect (OSTI)

Over forty years, there have been major efforts to aim at understanding the properties of surfaces, structure, composition, dynamics on the molecular level and at developing the surface science of heterogeneous and homogeneous catalysis. Since most catalysts (heterogeneous, enzyme and homogeneous) are nanoparticles, colloid synthesis methods were developed to produce monodispersed metal nanoparticles in the 1-10 nm range and controlled shapes to use them as new model catalyst systems in two-dimensional thin film form or deposited in mezoporous three-dimensional oxides. Studies of reaction selectivity in multipath reactions (hydrogenation of benzene, cyclohexene and crotonaldehyde) showed that reaction selectivity depends on both nanoparticle size and shape. The oxide-metal nanoparticle interface was found to be an important catalytic site because of the hot electron flow induced by exothermic reactions like carbon monoxide oxidation.

Somorjai, Gabor A.

2008-02-06T23:59:59.000Z

4

HETEROGENEOUS CATALYSIS RESEARCH MEETING  

E-Print Network [OSTI]

Williams) Transition~Metal Carbides Heterogeneous CatalysisActivity of Transition-Metal Carbides Wendell S. Williamsand testing of transition-metal carbide electrodes for

Authors, Various

2011-01-01T23:59:59.000Z

5

ISOTOPE METHODS IN HOMOGENEOUS CATALYSIS.  

SciTech Connect (OSTI)

The use of isotope labels has had a fundamentally important role in the determination of mechanisms of homogeneously catalyzed reactions. Mechanistic data is valuable since it can assist in the design and rational improvement of homogeneous catalysts. There are several ways to use isotopes in mechanistic chemistry. Isotopes can be introduced into controlled experiments and followed where they go or don't go; in this way, Libby, Calvin, Taube and others used isotopes to elucidate mechanistic pathways for very different, yet important chemistries. Another important isotope method is the study of kinetic isotope effects (KIEs) and equilibrium isotope effect (EIEs). Here the mere observation of where a label winds up is no longer enough - what matters is how much slower (or faster) a labeled molecule reacts than the unlabeled material. The most careti studies essentially involve the measurement of isotope fractionation between a reference ground state and the transition state. Thus kinetic isotope effects provide unique data unavailable from other methods, since information about the transition state of a reaction is obtained. Because getting an experimental glimpse of transition states is really tantamount to understanding catalysis, kinetic isotope effects are very powerful.

BULLOCK,R.M.; BENDER,B.R.

2000-12-01T23:59:59.000Z

6

Molecular-Level Design of Heterogeneous Chiral Catalysis  

SciTech Connect (OSTI)

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.

Francisco Zaera

2012-03-21T23:59:59.000Z

7

Homogeneous vs Heterogeneous Clustered Sensor Networks: A Comparative Study  

E-Print Network [OSTI]

1 Homogeneous vs Heterogeneous Clustered Sensor Networks: A Comparative Study Vivek Mhatre elected, serve for the entire lifetime of the network) in a homoge- neous network, it is evident

Rosenberg, Catherine P.

8

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

E-Print Network [OSTI]

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

Boyer, Edmond

9

Percolation and homogenization theories for heterogeneous materials  

E-Print Network [OSTI]

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 ...

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

2008-01-01T23:59:59.000Z

10

Forensic Tracking and Surveillance Algorithms for Homogeneous and Heterogeneous Settings  

E-Print Network [OSTI]

Forensic Tracking and Surveillance Algorithms for Homogeneous and Heterogeneous Settings Submitted-Kuwari) Date: #12;"I cannot succeed except through God" #12;Abstract Digital forensics is an emerging field. Traditionally, digital forensics has been confined to the extraction of digital evidence from electronic devices

Sheldon, Nathan D.

11

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

E-Print Network [OSTI]

material for materials and energy. Its abundance has garnered much interest in the scientific communityJournal of Molecular Catalysis A: Chemical 251 (2006) 8­23 Design and study of homogeneous the landscape of the current materials and energy industries. Natural gas continues to represent a vast source

Goddard III, William A.

12

DOE Laboratory Catalysis Research Symposium - Abstracts  

SciTech Connect (OSTI)

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.

Dunham, T.

1999-02-01T23:59:59.000Z

13

Charge Transfer and Support Effects in Heterogeneous Catalysis  

SciTech Connect (OSTI)

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

Hervier, Antoine

2011-12-21T23:59:59.000Z

14

Mechanistic Studies at the Interface Between Organometallic Chemistry and Homogeneous Catalysis  

SciTech Connect (OSTI)

Mechanistic Studies at the Interface Between Organometallic Chemistry and Homogeneous Catalysis Charles P. Casey, Principal Investigator Department of Chemistry, University of Wisconsin - Madison, Madison, Wisconsin 53706 Phone 608-262-0584 FAX: 608-262-7144 Email: casey@chem.wisc.edu http://www.chem.wisc.edu/main/people/faculty/casey.html Executive Summary. Our goal was to learn the intimate mechanistic details of reactions involved in homogeneous catalysis and to use the insight we gain to develop new and improved catalysts. Our work centered on the hydrogenation of polar functional groups such as aldehydes and ketones and on hydroformylation. Specifically, we concentrated on catalysts capable of simultaneously transferring hydride from a metal center and a proton from an acidic oxygen or nitrogen center to an aldehyde or ketone. An economical iron based catalyst was developed and patented. Better understanding of fundamental organometallic reactions and catalytic processes enabled design of energy and material efficient chemical processes. Our work contributed to the development of catalysts for the selective and mild hydrogenation of ketones and aldehydes; this will provide a modern green alternative to reductions by LiAlH4 and NaBH4, which require extensive work-up procedures and produce waste streams. (C5R4OH)Ru(CO)2H Hydrogenation Catalysts. Youval Shvo described a remarkable catalytic system in which the key intermediate (C5R4OH)Ru(CO)2H (1) has an electronically coupled acidic OH unit and a hydridic RuH unit. Our efforts centered on understanding and improving upon this important catalyst for reduction of aldehydes and ketones. Our mechanistic studies established that the reduction of aldehydes by 1 to produce alcohols and a diruthenium bridging hydride species occurs much more rapidly than regeneration of the ruthenium hydride from the diruthenium bridging hydride species. Our mechanistic studies require simultaneous transfer of hydride from ruthenium to the aldehyde carbon and of a proton from the CpOH unit to the aldehyde oxygen and support reduction of the aldehyde without its prior coordination to ruthenium. Another important step in the catalysis is the regeneration of 1 from reaction of H2 with the stable diruthenium bridging hydride complex 2. Studies of the microscopic reverse of this process (hydrogen evolution from 1 which occurs at 80 �������°C) in the presence of alcohol (the product of aldehyde hydrogenation) have shown that a dihydrogen complex is formed reversibly at a rate much faster than hydrogen evolution. Kinetic and theoretical studies in collaboration with Professor Qiang Cui of Wisconsin indicated an important role for alcohol in mediating transfer of hydrogen to ruthenium. One key to developing more active catalysts was to destabilize the bridging hydride intermediate 2 to prevent its formation or to speed its conversion to a reactive monohydride 1 by reaction with H2. We found several successful ways to destabilize the bridging hydride and to obtain more active catalysts. Most recently, we discovered related iron catalysts for hydrogenation that do not form dimers; the cost advantage of iron catalysts is spectacular. Iron Catalysts. In an exciting development, we found that a related iron complex is also a very active ketone hydrogenation catalyst. This hydrogenation catalyst shows high chemoselectivity for aldehydes, ketones, and imines and isolated C=C, C���¯�������ºC, C-X, -NO2, epoxides, and ester functions are unaffected by the hydrogenation conditions. Mechanistic studies have established a reversible hydrogen transfer step followed by rapid dihydrogen activation. The same iron complex also catalyzes transfer hydrogenation of ketones.

Charles P. Casey

2012-11-14T23:59:59.000Z

15

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

SciTech Connect (OSTI)

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.

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

1999-01-05T23:59:59.000Z

16

Bifurcation behavior in homogeneous-heterogeneous combustion. Part 2; Computations for stagnation-point flow  

SciTech Connect (OSTI)

Bifurcation analysis of ignition and extinction of combustion in stagnation-point flow was carried out for conditions when both homogeneous and heterogeneous reactions can occur. A technique based on the bifurcation theory and the shooting algorithm is developed, which permits fast and efficient tracking of bifurcation in these systems. The influences of the different parameters on the ignition and extinction behavior were investigated by assuming (1) only catalytic surface (heterogeneous) reaction, (2) only homogeneous reaction on a hot inert surface, and (3) both surface and homogeneous reactions. The coupling effects of the homogeneous and heterogeneous reactions are clearly demonstrated. It is shown that the heterogeneous reaction dominates the system behavior at the lower temperature while both homogeneous and heterogeneous reactions play important role at higher temperature. It is predicted that the homogeneous ignition temperature is higher with surface reaction than without surface reaction. However, homogeneous-heterogeneous or homogeneous reaction alone. The numerical results for propane and for methane oxidation on platinum foil also show good qualitative agreements with the experimental results of Part I of this article, which include the two types of ignition, extinction and autothermal behavior of homogeneous-heterogeneous reactions.

Song, X.; Williams, W.R.; Schmidt, L.D.; Aris, R. (Dept. of Chemical Engineering and Materials Science, Univ. of Minnesota, Minneapolis, MN (US))

1991-04-01T23:59:59.000Z

17

Intrinsic reactivity feedback characteristics for safety analysis of heterogeneous and homogeneous LMFBR core designs  

SciTech Connect (OSTI)

This paper presents a comparison of the intrinsic reactivity feedback characteristics of homogeneous and heterogeneous LMFBR designs. The comparisons are shown for a 1000 MWth LMFBR core design. However, the applicability of the conclusions drawn from these comparisons are generic to larger LMFBRs. Consistent sodium void worth distributions have been calculated for heterogeneous and homogeneous 1000 MWth LMFBR core designs. The basic calculations were performed with three dimensional models using ENDF/B-III cross section data and first order perturbation theory.

Doncals, R.A.; Lake, J.A.

1982-01-01T23:59:59.000Z

18

MCNP5 Validation for Criticality Calculations: Homogeneous and Heterogeneous Systems  

E-Print Network [OSTI]

OF APPLICABILITY 51 6.1 General Area and Range of Applicability 51 6.2 Westinghouse Specific Area and Range.2 Heterogeneous Systems 42 4.3 Summary 45 5 STATISTICAL EVALUATION 46 5.1 Determination of Upper Subcritical Limit by USLSTATS 46 5.2 Determination of Upper Subcritical Limit Using Lower Tolerance Limit 49 6 AREA AND RANGE

Haviland, David

19

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

SciTech Connect (OSTI)

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.

Turski, R.; Yang, Shi-tien

1987-11-01T23:59:59.000Z

20

Homogeneous-heterogeneous core evaluation and structural-material selection. [LMFBR  

SciTech Connect (OSTI)

The safe and economic operation of an LMFBR is dependent on many diverse and in some cases conflicting design considerations. In particular, the judicious choice of a reactor core design can play a significant role in meeting safety and economic constraints. The main interest of this study is to compare the relative merits of two core concepts, homogeneous and heterogeneous, with respect to their neutronic performance.

Orechwa, Y.; Su, S.F.

1982-01-01T23:59:59.000Z

Note: This page contains sample records for the topic "homogeneous catalysis heterogeneous" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


21

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

E-Print Network [OSTI]

o P-159 Carbon Dioxide Hydrogenation for Methanol Synthesis:Carbon dioxide activation mechanisms for low temperature partial hydrogenation to methanol

Somorjai Ed., G.A.

2007-01-01T23:59:59.000Z

22

Converting Homogeneous to Heterogeneous in Electrophilic Catalysis using Monodisperse Metal Nanoparticles  

E-Print Network [OSTI]

Synthesis of One Nanometer Rh and Pt Particles Supported on Mesoporous Silica: Catalytic Activity for Ethylene and Pyrrole

Witham, Cole A.

2011-01-01T23:59:59.000Z

23

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

E-Print Network [OSTI]

measurements. With an infrared laser, heating and coolingbeam for detection. Infrared laser heating is a successful

Somorjai Ed., G.A.

2007-01-01T23:59:59.000Z

24

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

E-Print Network [OSTI]

due to low solubility of syngas remain a problem for e?cientof methane to form syngas. 2 However, the structure andin the production of syngas and hydrogen from fossil and

Somorjai Ed., G.A.

2007-01-01T23:59:59.000Z

25

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

E-Print Network [OSTI]

metal composites, nonmetal catalysts such as refractory compounds (borides, carbides,metal-coordination); H 2 -aided deoxygenation giving water plus a surface carbide (

Somorjai Ed., G.A.

2007-01-01T23:59:59.000Z

26

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

E-Print Network [OSTI]

112 Koningsberger, D.C. , 3 Konya, Zoltan, 179 Koptyug, IgorImre Labadi § , Zoltan Konya ‡ , Imre Kiricsi ‡ Department

Somorjai Ed., G.A.

2007-01-01T23:59:59.000Z

27

The Development and Application of Homogeneous and Heterogeneous Late Metal Complexes in Catalysis  

E-Print Network [OSTI]

optimization of any process can be done in significantly less time and with less effort than with a batch reactor.

Witham, Cole

2010-01-01T23:59:59.000Z

28

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

E-Print Network [OSTI]

producing results that in- dicate that iron loaded zeolite exhibits a strong ability to convert methanol

Somorjai Ed., G.A.

2007-01-01T23:59:59.000Z

29

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

E-Print Network [OSTI]

Department of Chemical and Petroleum Engineering, UniversityDepartment of Chemical and Petroleum Engineering, University

Somorjai Ed., G.A.

2007-01-01T23:59:59.000Z

30

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

E-Print Network [OSTI]

led to outstanding catalysts, showing an excellent activity without leaching of metal up to ten recycling

Somorjai Ed., G.A.

2007-01-01T23:59:59.000Z

31

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

E-Print Network [OSTI]

Catalytic Processes for Sustainable Biomass Con- version”Catalytic Processes for Sustainable Biomass Conversion Istv´Catalyses for New Sustainable Green Processes on Catalyst

Somorjai Ed., G.A.

2007-01-01T23:59:59.000Z

32

Bifurcation behavior in homogeneous-heterogeneous combustion. Part 1. ; Experimental results over platinum  

SciTech Connect (OSTI)

Ignition, extinction, and autothermal behavior of the homogeneous and heterogeneous oxidation reactions in air of NH{sub 3}, CH{sub 4}, C{sub 3}H{sub 8}, and an equipolar NH{sub 3}/CH{sub 4} mixture over resistively heated polycrystalline platinum foils was studied in an atmospheric pressure flow reactor as a function of low rate, fuel concentration, preheat temperature, and reactor geometry. Surface temperature versus power curves were experimentally determined for different compositions in these systems, which were in turn summarized in bifurcation diagrams of surface temperature or power as a function of fuel composition. Two ignitions (heterogeneous and homogeneous), one extinction and one self-sustaining autothermal steady state, were observed for all systems except NH{sub 3}/CH{sub 4} oxidation. The heterogeneous ignition occurred around 600 {degrees} C for CH{sub 4} and 200 {degrees} C for all other systems and was weakly dependent on the fuel composition. Long transients due to carbon formation were observed in the autothermal behavior for fuel-rich compositions in the CH{sub 4} system. A second heterogeneous ignition occurred in NH{sub 3}/CH{sub 4} oxidation, which ranged from 400 {degrees} to 600 {degrees} C. Homogeneous reaction ignited at surface temperatures ranging from 1050 {degrees} C for C{sub 3}H{sub 8} oxidation to 1500 {degrees} C for CH{sub 4} and NH{sub 3} oxidation. For C{sub 3}H{sub 8} and CH{sub 4} oxidation, the flame generally left the foil, but in NH {sub 3} oxidation a stable boundary layer flame was also observed under some conditions.

Williams, W.R.; Stenzel, M.T.; Song, X.; Schmidt, L.D. (Dept. of Chemical Engineering and Materials Science, Univ. of Minnesota, Minneapolis, MN (US))

1991-04-01T23:59:59.000Z

33

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

E-Print Network [OSTI]

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 ...

Keybl, Jaroslav

2011-01-01T23:59:59.000Z

34

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

SciTech Connect (OSTI)

Experimental discoveries followed by theoretical interpretations that pave the way of further advances by experimentalists is a developing pattern in modern surface chemistry and catalysis. The revolution of modern surface science started with the development of surface-sensitive techniques such as LEED, XPS, AES, ISS and SIMS, in which the close collaboration between experimentalists and theorists led to the quantitative determination of surface structure and composition. The experimental discovery of the chemical activity of surface defects and the trends in the reactivity of transitional metals followed by the explanations from the theoretical studies led to the molecular level understanding of active sites in catalysis. The molecular level knowledge, in turn, provided a guide for experiments to search for new generation of catalysts. These and many other examples of successes in experiment-and-theory-combined studies demonstrate the importance of the collaboration between experimentalists and theorists in the development of modern surface science.

Somorjai, Gabor A.; Li, Yimin

2009-11-21T23:59:59.000Z

35

In-situ study of the chemically driven flow fields in initiating homogeneous and heterogeneous nitromethane explosives  

SciTech Connect (OSTI)

Electromagnetic gauging has been used to make in-situ measurements of particle velocity and impulse at five Lagrangian positions in nitromethane (NM) during gas-gun-driven, shock-to-detonation experiments. Homogeneous initiation experiments were conducted using NM that was chemically sensitized (using an organic base) and heterogeneous initiation experiments were done with physically sensitized NM (using silica particles). In the homogeneous initiation experiments, some of the features we observed are consistent with the classical homogeneous initiation model, however, our measurements show that the superdetonation does not form immediately after an induction time. Considerably behind the initial shock, reaction causes a wave to build up over a discernible length and this wave evolves into a superdetonation which catches the initial shock. In the heterogeneous initiation experiments, the waveforms indicated that wave growth occurs primarily in the shock front, similar to earlier observations in other heterogeneous explosives. 21 refs., 8 figs., 3 tabs.

Sheffield, S.A.; Engelke, R.; Alcon, R.R.

1989-01-01T23:59:59.000Z

36

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

SciTech Connect (OSTI)

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.

J. Helble; Clara Smith; David Miller

2009-08-31T23:59:59.000Z

37

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

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

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

38

Th/U-233 Multi-recycle in Pressurized Water Reactors: Feasibility Study of Multiple Homogeneous and Heterogeneous Assembly Designs  

E-Print Network [OSTI]

considered in past literature [1, 2, 3, 4], primarily because of the potential for near breeders with Th. Various heterogeneous designs have been investigated using designs with seed and blanket configurations having different seed unit (SU) to blanket unit (BU) ratios. Compared to the homogeneous designs

Kemner, Ken

39

Theoretical Studies in Heterogenous Catalysis: Towards a Rational Design of Novel Catalysts for Hydrodesulfurization and Hydrogen Production  

SciTech Connect (OSTI)

Traditionally, knowledge in heterogeneous catalysis has come through empirical research. Nowadays, there is a clear interest to change this since millions of dollars in products are generated every year in the chemical and petrochemical industries through catalytic processes. To obtain a fundamental knowledge of the factors that determine the activity of heterogeneous catalysts is a challenge for modern science since many of these systems are very complex in nature. In principle, when a molecule adsorbs on the surface of a heterogeneous catalyst, it can interact with a large number of bonding sites. It is known that the chemical properties of these bonding sites depend strongly on the chemical environment around them. Thus, there can be big variations in chemical reactivity when going from one region to another in the surface of a heterogeneous catalyst. A main objective is to understand how the structural and electronic properties of a surface affect the energetics for adsorption processes and the paths for dissociation and chemical reactions. In recent years, advances in instrumentation and experimental procedures have allowed a large series of detailed works on the surface chemistry of heterogeneous catalysts. In many cases, these experimental studies have shown interesting and unique phenomena. Theory is needed to unravel the basic interactions behind these phenomena and to provide a general framework for the interpretation of experimental results. Ideally, theoretical calculations based on density-functional theory have evolved to the point that one should be able to predict patterns in the activity of catalytic surfaces. As in the case of experimental techniques, no single theoretical approach is able to address the large diversity of phenomena occurring on a catalyst. Catalytic surfaces are usually modeled using either a finite cluster or a two-dimensionally periodic slab. Many articles have been published comparing the results of these two approaches. An important advantage of the cluster approach is that one can use the whole spectrum of quantum-chemical methods developed for small molecules with relatively minor modifications. On the other hand, the numerical effort involved in cluster calculations increases rather quickly with the size of the cluster. This problem does not exist when using slab models. Due to the explicit incorporation of the periodicity of the crystal lattice through the Bloch theorem, the actual dimension of a slab calculation depends only on the size of the unit cell. In practical terms, the slab approach is mainly useful for investigating the behavior of adsorbates at medium and high coverages. Very large unit cells are required at the limit of low to zero coverage, or when examining the properties and chemical behavior of isolated defect sites in a surface. In these cases, from a computational viewpoint, the cluster approach can be much more cost effective than the slab approach. Slab and cluster calculations can be performed at different levels of sophistication: semi-empirical methods, simple ab initio Hartree-Fock, ab initio post-Hartree-Fock (CI, MP2, etc), and density functional theory. Density-functional (DF) based calculations frequently give adsorption geometries with a high degree of accuracy and predict reliable trends for the energetics of adsorption reactions. This article provides a review of recent theoretical studies that deal with the behavior of novel catalysts used for hydrodesulfurization (HDS) reactions and the production of hydrogen (i.e. catalytic processes employed in the generation of clean fuels). These studies involve a strong coupling of theory and experiment. A significant fraction of the review is focused on the importance of size-effects and correlations between the electronic and chemical properties of catalytic materials. The article begins with a discussion of results for the desulfurization of thiophene on metal carbides and phosphides, systems which have the potential to become the next generation of industrial HDS catalysts. Then, systematic studies con

Rodriguez,J.A.; Liu, P.

2008-10-01T23:59:59.000Z

40

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

SciTech Connect (OSTI)

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.

Gerhard Strydom; Su-Jong Yoon

2014-04-01T23:59:59.000Z

Note: This page contains sample records for the topic "homogeneous catalysis heterogeneous" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


41

HETEROGENEOUS CATALYSIS RESEARCH MEETING  

E-Print Network [OSTI]

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

Authors, Various

2011-01-01T23:59:59.000Z

42

HETEROGENEOUS CATALYSIS RESEARCH MEETING  

E-Print Network [OSTI]

Activity of Transition-Metal Carbides Wendell S. Williamsand testing of transition-metal carbide electrodes forproperties of transition metal carbides in the writervs

Authors, Various

2011-01-01T23:59:59.000Z

43

catalysis | EMSL  

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

catalysis catalysis Leads No leads are available at this time. Magnesium behavior and structural defects in Mg+ ion implanted silicon carbide. Abstract: As a candidate material for...

44

New aspects in the analysis of loss-of-flow transients for homogeneous and heterogeneous LMFBR cores  

SciTech Connect (OSTI)

This paper presents the results of analyses of unprotected loss-of-flow (LOF) transients which have been performed to date using the new SAS4A code system. Accident histories for homogeneous and heterogeneous demo-sized cores (300 MWe) are compared and emphasis is placed on phenomena occurring after the initiation of fuel motion as described by LEVITATE. LEVITATE is the SAS4A model for the analysis of fuel and cladding dynamics under loss-of-flow (LOF) conditions and is believed to be the most-sophisticated computational tool currently available for fuel-motion analysis. The results of this analysis indicate that the initiation phase of an unprotected loss-of-flow accident has a considerably lower energetics potential in a heterogeneous core than in a homogeneous core. The difference is larger than previously indicated by SAS3D. Better phenomenological models implemented in SAS4A provide increased confidence in this aspect of safety evaluation of LMFBR cores.

Tentner, A.M.; Wider, H.U.

1982-01-01T23:59:59.000Z

45

On the critical salt concentrations for particle detachment in homogeneous sand and heterogeneous Hanford sediments  

E-Print Network [OSTI]

Hanford sediments Theresa Blumea,b , Noam Weisbrodc,*, John S. Selkera a Department of Bioengineering) mineralogically heterogeneous sediment, taken from the Hanford formation in southeast Washington. Stepwise the amount of particles released and the CSC were an order of magnitude higher for the Hanford sediment than

Selker, John

46

On the critical salt concentrations for particle detachment in homogeneous sand and heterogeneous Hanford sediments  

E-Print Network [OSTI]

Hanford sediments Abstract One of the mechanisms for sudden particle release is a decrease in groundwater and (b) mineralogically heterogeneous sediment, taken from the Hanford formation in southeast Washington the amount of particles released and the CSC were an order of magnitude higher for the Hanford sediment than

Weisbrod, Noam

47

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

E-Print Network [OSTI]

. Audigane, BRGM, E. Mouche, CEA, S. Viseur, CEREGE, D. Guérillot, TERRA 3E And the H-CUBE team Key words-scaling processes We propose to assess the buoyant forces on the CO2 and brine vertical migration of heterogeneity field distribution on the same 3D static earth model appropriate ranking measures of the static

Paris-Sud XI, Université de

48

An investigation of homogeneous and heterogeneous sonochemistry for destruction of hazardous waste. 1998 annual progress report  

SciTech Connect (OSTI)

'The primary objective of this research project is to acquire a deeper fundamental knowledge of acoustic cavitation and cavitation chemistry, and in doing so, to ascertain how ultrasonic irradiation can be more effectively applied to environmental problems. The primary objective will be accomplished by examining numerous aspects of sonochemical systems and acoustic cavitation. During the course of the project, the research group will investigate the significance of physical variables during sonolysis, sonochemical kinetics and reactive intermediates, and the behavior of heterogeneous (solid/liquid) systems. An additional component of the project includes utilizing various techniques to image cavitation bubble cloud development. This report summarizes results after 2 years of a 3 year investigation. Four on-going projects will be described. The first project is the destruction of polychlorinated biphenyls at multiple ultrasonic frequencies. The second project is a comprehensive study of how ultrasonic frequency influences sonochemical reaction rates; in particular, hydrogen peroxide formation. Finally, the sonochemical destruction of the pesticides dichlorvos (at 500 kHz) and carbofuran (parallel-plate reactor) has been examined.'

Hua, I.

1998-06-01T23:59:59.000Z

49

Summary Report on New Transmutation Analysis for the Evaluation of Homogeneous and Heterogeneous Options in Fast Reactors  

SciTech Connect (OSTI)

A 1000 MWth commercial-scale Sodium Fast Reactor (SFR) design was selected as the baseline in this scenario study. Traditional approaches to Light Water Reactor (LWR) Spent Nuclear Fuel (SNF) transuranic waste (TRU) burning in a fast spectrum system have typically focused on the continual homogeneous recycling (reprocessing) of the discharge fast reactor fuel. The effective reduction of transuranic inventories has been quantified through the use of the transuranics conversion ratio (TRU CR). The implicit assumption in the use of this single parameter is a homogeneous fast reactor option where equal weight is given to the destruction of transuranics, either by fission or eventual fission via transmutation. This work explores the potential application of alternative fast reactor fuel cycles in which the minor actinide (MA) component of the TRU is considered ‘waste’, while the plutonium component is considered as fuel. Specifically, a set of potential designs that incorporate radial heterogeneous target assemblies is proposed and results relevant to transmutation and system analysis are presented. In this work we consider exclusively minor actinide-bearing radial targets in a continual reprocessing scenario (as opposed to deep-burn options). The potential use of targets in a deep burn mode is not necessarily ruled out as an option. However, due to work scope constraints and material limit considerations, it was preferred to leave the target assemblies reach either the assumed limit of 200 DPA at discharge or maximum allowable gas pressure caused by helium production from transmutation. The number and specific design of the target assemblies was chosen to satisfy the necessary core symmetry and physical dimensions (available space for a certain amount of mass in an assembly based on an iterated mass density).

R. M. Ferrer; S. Bays; M. Pope; B. Forget; W. Skerjanc; M. Asgari

2008-08-01T23:59:59.000Z

50

High mass resolution time of flight mass spectrometer for measuring products in heterogeneous catalysis in highly sensitive microreactors  

SciTech Connect (OSTI)

We demonstrate a combined microreactor and time of flight system for testing and characterization of heterogeneous catalysts with high resolution mass spectrometry and high sensitivity. Catalyst testing is performed in silicon-based microreactors which have high sensitivity and fast thermal response. Gas analysis is performed with a time of flight mass spectrometer with a modified nude Bayard-Alpert ionization gauge as gas ionization source. The mass resolution of the time of flight mass spectrometer using the ion gauge as ionization source is estimated to m/{Delta}m > 2500. The system design is superior to conventional batch and flow reactors with accompanying product detection by quadrupole mass spectrometry or gas chromatography not only due to the high sensitivity, fast temperature response, high mass resolution, and fast acquisition time of mass spectra but it also allows wide mass range (0-5000 amu in the current configuration). As a demonstration of the system performance we present data from ammonia oxidation on a Pt thin film showing resolved spectra of OH and NH{sub 3}.

Andersen, T.; Jensen, R.; Christensen, M. K.; Chorkendorff, I. [Department of Physics, Danish National Research Foundation's Center for Individual Nanoparticle Functionality (CINF), Technical University of Denmark, Building 312, DK-2800 Kgs. Lyngby (Denmark); Pedersen, T.; Hansen, O. [Department of Micro- and Nanotechnology, Technical University of Denmark, DTU Nanotech Building 345 East, DK-2800 Kgs. Lyngby (Denmark)

2012-07-15T23:59:59.000Z

51

EMSL - catalysis  

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

catalysis en Duets by molecules and plasmons http:www.emsl.pnl.govemslwebnewsduets-molecules-and-plasmons

52

Reaction Selectivity in Heterogeneous Catalysis  

E-Print Network [OSTI]

possible adsorption modes of acrolein to a Pt(111) surface,possible adsorption structures of acrolein on Pt(111) energyand 2 Langmuir exposure of acrolein to Pt(111). Figure taken

Somorjai, Gabor A.

2010-01-01T23:59:59.000Z

53

INSTITUTE FOR INTEGRATED CATALYSIS Catalysis Research for  

E-Print Network [OSTI]

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

54

2012 Catalysis Lectures  

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

Bert Weckhuysen, who holds the chair of Inorganic Chemistry and Catalysis at Utrecht University, will give a series of catalysis lectures during his sabbatical period at...

55

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

SciTech Connect (OSTI)

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)

Not Available

1990-03-01T23:59:59.000Z

56

An Investigation of Homogeneous and Heterogeneous Sonochemistry for Destruction of Hazardous Waste - Final Report - 09/15/1996 - 09/14/2000  

SciTech Connect (OSTI)

During the last 20 years, various legislative acts have mandated the reduction and elimination of water and land pollution. In order to fulfill these mandates, effective control and remediation methods must be developed and implemented. The drawbacks of current hazardous waste control methods motivate the development of new technology, and the need for new technology is further driven by the large number of polluted sites across the country. This research explores the application and optimization of ultrasonic waves as a novel method by which aqueous contaminants are degraded. The primary objective of the investigation is to acquire a deeper fundamental knowledge of acoustic cavitation and cavitation chemistry, and in doing so, to ascertain how ultrasonic irradiation can be more effectively applied to environmental problems. Special consideration is given to the types of problems and hazardous chemical substrates found specifically at Department of Energy (DOE) sites. The experimental work is divided into five broad tasks, to be completed over a period of three years. The first task is to explore the significance of physical variables during sonolysis, such as ultrasonic frequency. The second aim is an understanding of sonochemical degradation kinetics and by-products, complemented by information from the detection of reactive intermediates with electron paramagnetic resonance. The sonolytic decomposition studies will focus on polychlorinated biphenyls (PCBs). Investigation of activated carbon regeneration during ultrasonic irradiation extends sonochemical applications in homogeneous systems to heterogeneous systems of environmental interest. Lastly, the physics and hydrodynamics of cavitation bubbles and bubble clouds will be correlated with sonochemical effects by performing high-speed photographic studies of acoustically cavitating aqueous solutions. The most important benefit will be fundamental information which will allow a more optimal application of ultrasonic irradiation to environmental problems.

Hua, Inez

2000-09-14T23:59:59.000Z

57

Zeolite catalysis  

SciTech Connect (OSTI)

This patent describes a process for preparing hydrocarbons boiling in the gasoline and/or distillate range by contacting a feedstock comprising lower molecular weight olefins in a reaction zone under conditions of elevated temperature and pressure with a shape selective crystalline aluminosilicate catalyst, comprising: reducing the non-shape selective surface-cracking and/or surface isomerization activity of the aluminosilicate catalyst by a process comprising: preparing an aqueous solution comprising colloidal silica, optionally an organic directing agent, and a source of hydroxide ions; mixing the aqueous solution with an aqueous dispersion of shape-selective crystalline aluminosilicate to form a homogeneous mixture which is subsequently heated; adding an aqueous solution comprising a source of fluoride ions to the homogeneous mixture to form a reactive composition; heating the reactive composition at a temperature to effectively form a surface-deactivated catalyst comprising a crystalline fluoride-containing silica outer shell on an aluminosilicate; withdrawing the surface-deactivated catalyst from the reactive composition for washing, drying, and calcining of the catalyst; and removing the catalyst to the reaction zone for contact with the olefin feedstock.

Chu, P.; Garwood, W.E.; Schwartz, A.B.

1988-11-29T23:59:59.000Z

58

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

SciTech Connect (OSTI)

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.

Behrens, Malte

2012-03-28T23:59:59.000Z

59

Postdoctoral Scholar position Area: Heterogeneous Catalysis  

E-Print Network [OSTI]

: Immediately Salary: $40,000-$50,000 per year(plus benefits) The Department of Chemical and Petroleum with high performance and novel catalytic processes for efficient energy utilization in an economical evaluation as well as reactor system design and fabrication Creative problem-solving and strong critical

de Leon, Alex R.

60

Center for Catalysis at Iowa State University  

SciTech Connect (OSTI)

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)

Kraus, George A.

2006-10-17T23:59:59.000Z

Note: This page contains sample records for the topic "homogeneous catalysis heterogeneous" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


61

EMSL - In situ catalysis  

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

situ-catalysis en Local environment and composition of magnesium gallium layered double hydroxides determined from solid-state 1H and 71Ga NMR http:www.emsl.pnl.govemslweb...

62

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

SciTech Connect (OSTI)

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.

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

2011-10-01T23:59:59.000Z

63

Fundamental studies of reactive intermediates in homogeneous catalysis  

SciTech Connect (OSTI)

The studies involve dissociation of Fe(CO){sub n}{sup {minus}}, Ni(CO){sub n}{sub {minus}}, and other carbonyl anions; decarboxylation of (CO){sub 4}FeCOOH{sup {minus}} to form CO{sub 2} and (CO){sub 4}FeH{sup {minus}} in the water gas shift reaction; gas-phase bimolecular reactions of carbonyl anions and O{sub 2}; reaction of O{sub 2} with CpMn(CO){sub 2}{sup {minus}}; gas-phase chemistry of fullerene anions; and gas-phase thermochemistry of bicarbonate ion, bisulfite ion, and their conjugate acids (sulfonate ion was produced).

Not Available

1993-10-01T23:59:59.000Z

64

Homogeneous Catalysis Selective Oxidation of Methane to Methanol  

E-Print Network [OSTI]

oxidizing agent than SVI ions (Eo = 1.5 V SeO4 2À /H2SeO3, Eo = 0.17 V SO4 2À /H2SO3, respec- tively) and, critically, the hydrated form, selenic acid (H2SeO4), is known to oxidize gold metal.[7] Equally impor- tant

Goddard III, William A.

65

Phase selectively soluble polymer supports to facilitate homogeneous catalysis  

E-Print Network [OSTI]

Soluble polymers that have phase selective solubility are useful in synthesis because they simplify purification and separation. Such selectively soluble polymers simplify catalyst, reagent, and product recovery and enable the use of Green chemistry...

Ortiz-Acosta, Denisse

2009-05-15T23:59:59.000Z

66

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:1 First Use of Energy for All Purposes (Fuel and Nonfuel),Feet) Year Jan Feb Mar Apr MayAtmospheric Optical Depth7-1D: Vegetation ProposedUsingFun withconfinement plasmas inPortal StartupdefaultThe benefits ofEnergyAmes

67

Polyisobutylene as a Polymer Support for Homogeneous Catalysis  

E-Print Network [OSTI]

of 5 cycles In 2005, Zhang described immobilization of Cinchona alkaloids with an anthraquinone core onto PEG 5000 (eq. 9). 21 This PEG-bound alkaloid 6was used in asymmetric dihydroxylation with various alkenes with high stereoselectivities...

Hongfa, Chayanant

2010-01-14T23:59:59.000Z

68

Catalysis Research for Energy Independence  

E-Print Network [OSTI]

production and use, and catalysis lies at the core of efficiently and effectively using our current energy, converting carbon dioxide into fuels, and transforming electrical energy from renewable energy sourcesCatalysis Research for Energy Independence Chemical transformations are at the heart of energy

69

asymmetric catalysis stereoelectronic: Topics by E-print Network  

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

X Lewis Acid Catalysis Brnsted Acid Catalysis X Johnson, Jeff S. 2 Multidimensional free energy relationships in asymmetric catalysis. Open Access Theses and Dissertations...

70

Magnetic catalysis and inverse magnetic catalysis in QCD  

E-Print Network [OSTI]

We investigate the effects of strong magnetic fields on the QCD phase structure at vanishing density by solving the gluon and quark gap equations, and by studying the dynamics of the quark scattering with the four-fermi coupling. The chiral crossover temperature as well as the chiral condensate are computed. For asymptotically large magnetic fields we find magnetic catalysis, while we find inverse magnetic catalysis for intermediate magnetic fields. Moreover, for large magnetic fields the chiral phase transition for massless quarks turns into a crossover. The underlying mechanisms are then investigated analytically within a few simplifications of the full numerical analysis. We find that a combination of gluon screening effects and the weakening of the strong coupling is responsible for the phenomenon of inverse catalysis. In turn, the magnetic catalysis at large magnetic field is already indicated by simple arguments based on dimensionality.

Niklas Mueller; Jan M. Pawlowski

2015-02-27T23:59:59.000Z

71

Tomographic Characterization of Aquifer Heterogeneity  

E-Print Network [OSTI]

that extend the 3D homogenous spherical radial equation to the heterogeneous case. A numerical model was used to check the heterogeneous extension for accuracy. High quality zero-offset profile ray paths (ZOP) were used to determine hydraulic conductivity, K...

Lyle, Shane

2011-05-31T23:59:59.000Z

72

Enhanced Micellar Catalysis LDRD.  

SciTech Connect (OSTI)

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.

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

2012-12-01T23:59:59.000Z

73

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

E-Print Network [OSTI]

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...

Wang, Qingqing

2012-07-16T23:59:59.000Z

74

Fuel Synthesis Catalysis Laboratory (Fact Sheet)  

SciTech Connect (OSTI)

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

Not Available

2011-07-01T23:59:59.000Z

75

Fuel Synthesis Catalysis Laboratory (Fact Sheet)  

SciTech Connect (OSTI)

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

Not Available

2013-07-01T23:59:59.000Z

76

Laboratory investigations of effective flow behavior in unsaturated heterogeneous sands  

E-Print Network [OSTI]

Laboratory investigations of effective flow behavior in unsaturated heterogeneous sands D, Lyngby Abstract. Two-dimensional unsaturated flow and transport through heterogeneous sand was investigated under controlled laboratory conditions. The unsaturated hydraulic conductivity of five homogeneous

Wildenschild, Dorthe

77

Charge Transfer and Support Effects in Heterogeneous Catalysis  

E-Print Network [OSTI]

Titanium  Oxide  as  an  Electronically  Active  Support  for  Platinum in the Catalytic Oxidation of Carbon Monoxide.  .  .  .  .  .  .  .  .  .  .  .  .  carbon  monoxide  oxidation  on  platinum  nanoparticles  supported  on  stoichiometric  titanium Titanium Oxide as an Electronically Active  Support for Platinum in  the Catalytic Oxidation of Carbon  Monoxide   

Hervier, Antoine

2012-01-01T23:59:59.000Z

78

Heterogeneous Catalysis DOI: 10.1002/anie.201200699  

E-Print Network [OSTI]

- cial processes unattractive. Several non-noble metal materi- als, such as transition-metal chalcogenides,[2] carbides,[3] and complexes[4] as well as metal alloys[5] have been widely investigated. Nitrides of early transition-metals have been shown to have excellent catalytic activities in a variety

Frenkel, Anatoly

79

Heterogeneous Catalysis on Atomically Dispersed Supported Metals: CO2  

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:1 First Use of Energy for All Purposes (Fuel and Nonfuel),Feet) Year Jan Feb Mar Apr MayAtmospheric Optical Depth7-1D: Vegetation ProposedUsingFun with Bigfront.jpgcommunity200cellHeat TransferHelpingEnergyHerman

80

Textured Metal Catalysts for Heterogeneous Catalysis - Energy Innovation  

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

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Note: This page contains sample records for the topic "homogeneous catalysis heterogeneous" from the National Library of EnergyBeta (NLEBeta).
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81

Control Heterogeneous Catalysis at Atomic and Electronic-level Using  

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

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82

The Role of Catalyst Surface Structure in Heterogeneous Catalysis |  

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:1 First Use of Energy for All Purposes (Fuel and Nonfuel),Feet) Year Jan Feb Mar Apr May JunDatastreamsmmcrcalgovInstrumentsrucLas ConchasPassiveSubmittedStatus TomAboutManusScienceThe Life of EnricoFlickr

83

Heterogeneous effects in fast breeder reactors  

E-Print Network [OSTI]

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 ...

Gregory, Michael Vladimir

1973-01-01T23:59:59.000Z

84

Essays on economies with heterogeneous labor  

E-Print Network [OSTI]

In this thesis, I study two different economies that consist of heterogeneous labor. By allowing for differences among individuals where previous analyses restricted attention to homogeneous labor, I am able to understand ...

Lehr, Brandon Charles

2010-01-01T23:59:59.000Z

85

Basic Research Needs: Catalysis for Energy  

SciTech Connect (OSTI)

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.

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

2008-03-11T23:59:59.000Z

86

SOUTHWEST CATALYSIS SOCIETY 2008 SPRING SYMPOSIUM  

E-Print Network [OSTI]

Design: FCC Feed Hydrotreating Catalysis 11:35 AM Lunch Break/Poster Preview 1:00 PM Zachary T. Ball

Natelson, Douglas

87

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

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

& Publications Low-Temperature HydrocarbonCO Oxidation Catalysis in Support of HCCI Emission Control Low-Temperature HydrocarbonCO Oxidation Catalysis in Support of HCCI...

88

Bimetallic and Ternary Alloys for Improved Oxygen Reduction Catalysis...  

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

Bimetallic and Ternary Alloys for Improved Oxygen Reduction Catalysis . Bimetallic and Ternary Alloys for Improved Oxygen Reduction Catalysis . Abstract: The research described in...

89

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

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

Conversion: Using Heat and Catalysis to Make Biofuels and Bioproducts Thermochemical Conversion: Using Heat and Catalysis to Make Biofuels and Bioproducts The Bioenergy...

90

"Nanocrystal bilayer for tandem catalysis"  

SciTech Connect (OSTI)

Supported catalysts are widely used in industry and can be optimized by tuning the composition and interface of the metal nanoparticles and oxide supports. Rational design of metal-metal oxide interfaces in nanostructured catalysts is critical to achieve better reaction activities and selectivities. We introduce here a new class of nanocrystal tandem catalysts that have multiple metal-metal oxide interfaces for the catalysis of sequential reactions. We utilized a nanocrystal bilayer structure formed by assembling platinum and cerium oxide nanocube monolayers of less than 10 nm on a silica substrate. The two distinct metal-metal oxide interfaces, CeO2-Pt and Pt-SiO2, can be used to catalyse two distinct sequential reactions. The CeO2-Pt interface catalysed methanol decomposition to produce CO and H2, which were subsequently used for ethylene hydroformylation catalysed by the nearby Pt-SiO2 interface. Consequently, propanal was produced selectively from methanol and ethylene on the nanocrystal bilayer tandem catalyst. This new concept of nanocrystal tandem catalysis represents a powerful approach towards designing high-performance, multifunctional nanostructured catalysts

Yamada, Yusuke; Tsung, Chia Kuang; Huang, Wenyu; Huo, Ziyang; E.Habas, Susan E; Soejima, Tetsuro; Aliaga, Cesar E; Samorjai, Gabor A; Yang, Peidong

2011-01-24T23:59:59.000Z

91

asymmetric catalysis solvent-free: Topics by E-print Network  

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

X Lewis Acid Catalysis Brnsted Acid Catalysis X Johnson, Jeff S. 2 Multidimensional free energy relationships in asymmetric catalysis. Open Access Theses and Dissertations...

92

Nanocrystal assembly for tandem catalysis  

DOE Patents [OSTI]

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.

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

2014-10-14T23:59:59.000Z

93

Magnetic Catalysis vs Magnetic Inhibition  

E-Print Network [OSTI]

We discuss the fate of chiral symmetry in an extremely strong magnetic field B. We investigate not only quark fluctuations but also neutral meson effects. The former would enhance the chiral-symmetry breaking at finite B according to the Magnetic Catalysis, while the latter would suppress the chiral condensate once B exceeds the scale of the hadron structure. Using a chiral model we demonstrate how neutral mesons are subject to the dimensional reduction and the low dimensionality favors the chiral-symmetric phase. We point out that this effect, the Magnetic Inhibition, can be a feasible explanation for recent lattice-QCD data indicating the decreasing behavior of the chiral-restoration temperature with increasing B.

Kenji Fukushima; Yoshimasa Hidaka

2012-09-06T23:59:59.000Z

94

On the role of interfacial hydrogen bonds in "on-water" catalysis  

E-Print Network [OSTI]

Numerous experiments have demonstrated that many classes of organic reactions exhibit increased reaction rates when performed in heterogeneous water emulsions. Despite enormous practical importance of the observed "on-water" catalytic effect and several mechanistic studies, its microscopic origins remains unclear. In this work, the second generation Car-Parrinello molecular dynamics method is extended to self-consistent charge density-functional based tight-binding in order to study "on-water" catalysis of the Diels-Alder reaction between dimethyl azodicarboxylate and quadricyclane. We find that the stabilization of the transition state by dangling hydrogen bonds exposed at the aqueous interfaces plays a significantly smaller role in "on-water" catalysis than has been suggested previously.

Kristof Karhan; Rustam Z. Khaliullin; Thomas D. Kühne

2014-08-21T23:59:59.000Z

95

aqueous phase catalysis: Topics by E-print Network  

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

corroborate asymmetry of catalysis in F0F1-ATP synthase. Zarrabi, Nawid; Diez, Manuel; Graeber, Peter; Wrachtrup, Joerg; Boersch, Michael 2007-01-01 292 Magnetic catalysis in hot...

96

Evaluation of the core physics and safety characteristics of a quasi-homogeneous LMFBR concept  

SciTech Connect (OSTI)

A core design concept utilizing two types of driver assemblies that differ in fuel pin diameter has been investigated as an alternative to the heterogeneous LMFBR core for achieving low HCDA energetics. Core designs based on the (quasi-homogeneous) concept were developed and their performance compared to that of standard homogeneous and hetergeneous cores. It is shown that quasi-homogenous cores can be designed which possess many of the performance advantages of homogeneous cores (such as reduced power mismatches and local power swings), while retaining the potential safty advantages of heterogeneous cores (such as an incoherent response during loss-of-flow accidents and a reduced coolant void reactivity worth).

Khalil, H.; Yarlagadda, B.S.

1984-01-01T23:59:59.000Z

97

Effective hydraulic conductivity of bounded, strongly heterogeneous porous media  

E-Print Network [OSTI]

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

Tartakovsky, Daniel M.

98

Mapping parallel programs to heterogeneous multi-core systems   

E-Print Network [OSTI]

Heterogeneous computer systems are ubiquitous in all areas of computing, from mobile to high-performance computing. They promise to deliver increased performance at lower energy cost than purely homogeneous, CPU-based ...

Grewe, Dominik

2014-06-27T23:59:59.000Z

99

Geometrically induced magnetic catalysis and critical dimensions  

E-Print Network [OSTI]

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 effect of the curvature. We discover that an infrared singularity may reappear from higher-order terms in the heat kernel expansion leading to a novel form of geometrically induced magnetic catalysis (absent in flat space). 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 behaviour of the magnetic shift changes qualitatively.

Antonino Flachi; Kenji Fukushima; Vincenzo Vitagliano

2015-02-21T23:59:59.000Z

100

Geometrically induced magnetic catalysis and critical dimensions  

E-Print Network [OSTI]

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 effect of the curvature. We discover that an infrared singularity may reappear from higher-order terms in the heat kernel expansion leading to a novel form of geometrically induced magnetic catalysis (absent in flat space). 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 behaviour of the magnetic shift changes qualitatively.

Flachi, Antonino; Vitagliano, Vincenzo

2015-01-01T23:59:59.000Z

Note: This page contains sample records for the topic "homogeneous catalysis heterogeneous" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


101

Homogenization of the criticality spectral equation in neutron transport  

E-Print Network [OSTI]

for the neutron transport equation in a periodic heterogeneous domain, modeling the criticality study of nuclearHomogenization of the criticality spectral equation in neutron transport Gr'egoire Allaire \\Lambda problem. This result justifies and improves the engineering procedure used in practice for nuclear reactor

Bal, Guillaume

102

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

E-Print Network [OSTI]

, in the pharmaceutical industry and in the food industry. Polyisobutylene was first developed by the BASF in 1931 and is sold under the trade name ?Oppanol B? or ?Glissopal? depending on its molecular weight. These commercial materials are produced via cationic... that require carbocationic polymerization, PIB oligomers used in this study were commercially available, inexpensive and available under the trade name Glissopal from BASF (MW = 1000, DP = 18 or MW = 2300, DP = 41). The Bergbreiter group is one of a number...

Boralugodage, Nilusha P

2013-06-05T23:59:59.000Z

103

USD Catalysis Group for Alternative Energy  

SciTech Connect (OSTI)

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.

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

2012-03-13T23:59:59.000Z

104

Nanoscale Advances in Catalysis and Energy Applications  

SciTech Connect (OSTI)

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.

Li, Yimin; Somorjai, Gabor A.

2010-05-12T23:59:59.000Z

105

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...

106

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...

107

Catalysis by Design - Theoretical and Experimental Studies of...  

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

Design - Theoretical and Experimental Studies of Model Catalysts for Lean NOx Treatment Catalysis by Design - Theoretical and Experimental Studies of Model Catalysts for Lean NOx...

108

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

Broader source: Energy.gov (indexed) [DOE]

vs. Plasma-Facilitated Lean NOx Catalysis Selective reduction of NOx in oxygen rich environments with plasma-assisted catalysis: Catalyst development and mechanistic...

109

A BRIEF HISTORY OF INDUSTRIAL CATALYSIS  

E-Print Network [OSTI]

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

Heinemann, Heinz

2013-01-01T23:59:59.000Z

110

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

E-Print Network [OSTI]

-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

Pennycook, Steve

111

Application of X-ray CT for investigating fluid flow and conformance control during CO2 injection in highly heterogeneous media  

E-Print Network [OSTI]

were performed using homogeneous and heterogeneous cores and a 4th generation X-Ray CT scanner was used to visualize heterogeneity and fluid flow in the core. Porosity and saturation measurements were made during the course of the experiment...

Chakravarthy, Deepak

2005-08-29T23:59:59.000Z

112

Lithium Diisopropylamide-Mediated Enolization: Catalysis by Hemilabile Ligands  

E-Print Network [OSTI]

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

Collum, David B.

113

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:1 First Use of Energy for All Purposes (Fuel and Nonfuel),Feet) Year Jan Feb Mar Apr MayAtmospheric Optical Depth7-1D: Vegetation Proposed New Substation Sites ProposedOccupational Health Services >Catalysis and Synthesis

114

Catalysis Working Group | Department of Energy  

Broader source: Energy.gov (indexed) [DOE]

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:1 First Use of Energy for All Purposes (Fuel and Nonfuel),Feet) Year Jan Feb Mar Apr May Jun Jul(Summary) "ofEarly Career Scientists' ResearchTheMarketing,Energy-ChevronSeveral salesCarolyn L.in aDataThe CatalysisThe

115

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:1 First Use of Energy for All Purposes (Fuel and Nonfuel),Feet) Year Jan Feb Mar Apr MayAtmosphericNuclear Security Administration the1 - September 2006 The 2002 WholesaleEnergy'sRunningOperations Two Argonnein Catalysis

116

Accounting for Scale in Catalysis | EMSL  

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:1 First Use of Energy for All Purposes (Fuel and Nonfuel),Feet) Year Jan Feb Mar Apr MayAtmospheric Optical Depth (AOD)ProductssondeadjustsondeadjustAbout the Building Technologies OfficeAccounting for Scale in Catalysis

117

Microgrids and Heterogeneous Power Quality and Reliability  

SciTech Connect (OSTI)

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.

LaCommare, Kristina; Marnay, Chris

2007-10-01T23:59:59.000Z

118

Experimental evidence of foam homogenization  

SciTech Connect (OSTI)

The propagation of an ionization wave through a subcritical foam is studied under inertial confinement fusion conditions. Independent measurements of the ionization wave velocity are compared with hydrodynamic simulations and analytical models. It is shown that simulations of a homogeneous material at equivalent density strongly overestimate the front velocity. The internal foam structure can be accounted for with a simple model of foam homogenization that allows improving agreement between experiment and calculations.

Nicolaie, Ph.; Olazabal-Loume, M.; Tikhonchuk, V. [Univ. Bordeaux-CNRS-CEA, CELIA F-33405 Talence cedex (France); Fujioka, S.; Sunahara, A. [Institute of Laser Engineering, Osaka University, 2-6 Yamada-oka, Suita Osaka 565-0871 (Japan); Borisenko, N.; Gus'kov, S.; Orekov, A. [P. N. Lebedev Physical Institute, RAS Leninskii Prospect 53, Moscow 119991 (Russian Federation); Grech, M. [Max-Planck-Institute for the Physics of Complex Systems, D-01187 Dresden (Germany); Riazuelo, G. [CEA, DAM, DIF, F-91297 Arpajon (France); Labaune, C. [Laboratoire pour l'Utilisation des Lasers Intenses, Ecole Polytechnique, Palaiseau (France); Velechowski, J. [Czech Technical University in Prague, Technicka 2, 166 27 Prague 6 (Czech Republic); Univ. Bordeaux-CNRS-CEA, CELIA F-33405 Talence cedex (France)

2012-11-15T23:59:59.000Z

119

Theoretical investigation of solar energy conversion and water oxidation catalysis  

E-Print Network [OSTI]

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 ...

Wang, Lee-Ping

2011-01-01T23:59:59.000Z

120

Catalysis Working Group Kick-Off Meeting Agenda | Department...  

Energy Savers [EERE]

Kick-Off Meeting Agenda 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,...

Note: This page contains sample records for the topic "homogeneous catalysis heterogeneous" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


121

Lean NOx Trap Catalysis for Lean Natural Gas Engine Applications  

SciTech Connect (OSTI)

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

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

2007-09-01T23:59:59.000Z

122

Value iteration for (switched) homogeneous systems  

E-Print Network [OSTI]

In this note, we prove that dynamic programming value iteration converges uniformly for discrete-time homogeneous systems and continuous-time switched homogeneous systems. For discrete-time homogeneous systems, rather than ...

Dahleh, Munther A.

123

Ice Nucleation on Carbon Surface Supports the Classical Theory for Heterogeneous Nucleation  

E-Print Network [OSTI]

The prevalence of heterogeneous nucleation in nature was explained qualitatively by the classical theory for heterogeneous nucleation established over more than 60 years ago, but the quantitative validity and the key conclusions of the theory have remained unconfirmed. Employing the forward flux sampling method and the coarse-grained water model mW, we explicitly computed the heterogeneous ice nucleation rates in the supercooled water on a graphitic surface at various temperatures. The independently calculated ice nucleation rates were found to fit well according to the classical theory for heterogeneous nucleation. The fitting procedure further yields the estimate of the potency factor which measures the ratio of the heterogeneous nucleation barrier to the homogeneous nucleation barrier. Remarkably, the estimated potency factor agrees quantitatively with the volumetric ratio of the critical nuclei between the heterogeneous and homogeneous nucleation. Our numerical study thus provides a strong support to the ...

Cabriolu, Raffaela

2015-01-01T23:59:59.000Z

124

Nanoscale Advances in Catalysis and Energy Applications  

E-Print Network [OSTI]

 J.Y.  Park,   The  nanoscience  revolution:  Merging  Nanocatalysis.   Nanoscience  and  technology,.    The  impact  of  nanoscience  on  heterogeneous  

Li, Yimin

2011-01-01T23:59:59.000Z

125

An Analysis of Heterogeneity in Futuristic Unmanned Vehicle Systems  

E-Print Network [OSTI]

and with enough automation aboard unmanned vehicles, inverting the multiple operators to single-vehicle control1 An Analysis of Heterogeneity in Futuristic Unmanned Vehicle Systems C.E. NEHME M.L. CUMMINGS paradigm is possible. These studies, however, have generally focused on homogeneous teams of vehicles

Cummings, Mary "Missy"

126

Heterogeneity of Nucleotide Frequencies Among Evolutionary Lineages and Phylogenetic Inference  

E-Print Network [OSTI]

Heterogeneity of Nucleotide Frequencies Among Evolutionary Lineages and Phylogenetic Inference is the homogeneity of nucleotide frequencies among taxa, which refers to the equality of the nucleotide frequency bias among species. Changes in nucleotide frequency among different lineages in a data set are thought

Rosenberg, Michael S.

127

HETEROGENEOUS MULTIPROCESSOR MAPPING FOR REAL-TIME STREAMING SYSTEMS  

E-Print Network [OSTI]

address the problem of multi-objective mapping of SDF graphs onto heterogeneous multi-processor platforms can be modeled by synchronous data flow (SDF) graphs [1]. Multiprocessor mapping of an SDF graph were focused on SDF mapping on homogeneous multiprocessors [1][2]. More recent ap- proaches have

Gerstlauer, Andreas

128

Heterogeneous cavitation in liquid helium 4 near a glass plate  

E-Print Network [OSTI]

Heterogeneous cavitation in liquid helium 4 near a glass plate X. Chavanne, S. Balibar and F wave to study cavitation, i.e. the nucleation of bubbles, in liquid helium 4 near a clean glass plate and threshold pressures in the range 0 to -3 bar, significantly less negative than for homogeneous cavitation

Caupin, Frédéric

129

Experiments and analysis for an axially heterogeneous LMR assembly at ZPPR  

SciTech Connect (OSTI)

Experiments in ZPPR-17 provided physics data for a full-scale (700 MWe) axially heterogeneous LMR. Measurements and analysis are reported for control rod worths, reaction rate distributions, gamma dose distribution, sodium void worths and criticality. Agreement between measurement and calculation are generally satisfactory, but the axial heterogeneity did introduce analytical complications. Some calculational methods gave less good agreement with measurements than in previous homogeneous or radially heterogeneous assemblies. 10 refs., 7 figs., 6 tabs.

Collins, P.J.; Brumbach, S. B.

1988-01-01T23:59:59.000Z

130

Reliable computation of homogeneous azeotropes  

SciTech Connect (OSTI)

It is important to determine the existence and composition of homogeneous azeotropes in the analysis of phase behavior and in the synthesis and design of separation systems, from both theoretical and practical standpoints. A new method for reliably locating any and all homogeneous azeotropes for multicomponent mixtures is presented. The method also verifies the nonexistence of homogeneous azeotropes if none are present. The method is based on interval analysis, in particular an interval-Newton/generalized-bisection-algorithm providing a mathematical and computational guarantee that all azeotropes are located. This general-purpose technique can be applied in connection with any thermodynamic models. The technique is illustrated in several example problems using the Wilson, NRTL, and UNIQUAC activity-coefficient models.

Maier, R.W.; Brennecke, J.F.; Stadtherr, M.A. [Univ. of Notre Dame, IN (United States). Dept. of Chemical Engineering] [Univ. of Notre Dame, IN (United States). Dept. of Chemical Engineering

1998-08-01T23:59:59.000Z

131

Some General Themes in Catalysis at LANL  

SciTech Connect (OSTI)

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.

Gordon, John C. [Los Alamos National Laboratory

2012-07-19T23:59:59.000Z

132

Discovering Homogeneous Regions in Spatial Data through Competition Slobodan Vucetic SVUCETIC@EECS.WSU.EDU  

E-Print Network [OSTI]

Discovering Homogeneous Regions in Spatial Data through Competition Slobodan Vucetic SVUCETIC for the analysis of heterogeneous spatial data is proposed. It is based on partitioning the data set into more. A number of experiments on artificial and real­life spatial data are performed to validate some as­ pects

Obradovic, Zoran

133

Discovering Homogeneous Regions in Spatial Data through Competition Slobodan Vucetic SVUCETIC@EECS.WSU.EDU  

E-Print Network [OSTI]

Discovering Homogeneous Regions in Spatial Data through Competition Slobodan Vucetic SVUCETIC, a supervised machine learning algorithm for the analysis of heterogeneous spatial data is proposed. It is based and accuracy is discussed. A number of experiments on artificial and real-life spatial data are performed

Vucetic, Slobodan

134

Security-Aware Resource Allocation for Real-Time Parallel Jobs on Homogeneous  

E-Print Network [OSTI]

processing systems [2], med- ical electronics [9], aircraft control [1], and scientific parallel computing [6 a system framework, security overhead, and parallel applications with deadline and security constraintsSecurity-Aware Resource Allocation for Real-Time Parallel Jobs on Homogeneous and Heterogeneous

Qin, Xiao

135

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

E-Print Network [OSTI]

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. ...

Blaylock, Donnie Wayne

2011-01-01T23:59:59.000Z

136

High Throughput Software for Powder Diffraction and its Application to Heterogeneous Catalysis  

E-Print Network [OSTI]

In this thesis we investigate high throughput computational methods for processing large quantities of data collected from synchrotrons and their application to spectral analysis of powder diffraction data. We also present the main product of this PhD programme, specifically a software called 'EasyDD' developed by the author. This software was created to meet the increasing demand on data processing and analysis capabilities as required by modern detectors which produce huge quantities of data. Modern detectors coupled with the high intensity X-ray sources available at synchrotrons have led to the situation where datasets can be collected in ever shorter time scales and in ever larger numbers. Such large volumes of datasets pose a data processing bottleneck which augments with current and future instrument development. EasyDD has achieved its objectives and made significant contributions to scientific research. It can also be used as a model for more mature attempts in the future. EasyDD is currently in use by a number of researchers in a number of academic and research institutions to process high-energy diffraction data. These include data collected by different techniques such as Energy Dispersive Diffraction, Angle Dispersive Diffraction and Computer Aided Tomography. EasyDD has already been used in a number of published studies, and is currently in use by the High Energy X-Ray Imaging Technology project. The software was also used by the author to process and analyse datasets collected from synchrotron radiation facilities. In this regard, the thesis presents novel scientific research involving the use of EasyDD to handle large diffraction datasets in the study of alumina-supported metal oxide catalyst bodies. These data were collected using Tomographic Energy Dispersive Diffraction Imaging and Computer Aided Tomography techniques.

Taha Sochi

2010-12-20T23:59:59.000Z

137

E-Print Network 3.0 - alkane oxidation catalysis Sample Search...  

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

hydrogen... Reforming of Methane 10 Gas Phase Incorporation of Pd onto Iron-Ceria Aerogels for Water Gas Shift Catalysis... at the 20 North American Meeting of the Catalysis...

138

acid-base catalysis ii: Topics by E-print Network  

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

corroborate asymmetry of catalysis in F0F1-ATP synthase. Zarrabi, Nawid; Diez, Manuel; Graeber, Peter; Wrachtrup, Joerg; Boersch, Michael 2007-01-01 232 Magnetic catalysis in hot...

139

Dedicated heterogeneous node scheduling including backfill scheduling  

DOE Patents [OSTI]

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.

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

2006-07-25T23:59:59.000Z

140

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

SciTech Connect (OSTI)

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/

Metiu, Horia [University of California, Santa Barbara

2014-08-22T23:59:59.000Z

Note: This page contains sample records for the topic "homogeneous catalysis heterogeneous" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


141

Catalysis-by-design impacts assessment  

SciTech Connect (OSTI)

Catalyst researchers have always recognized the need to develop a detailed understanding of the mechanisms of catalytic processes, and have hoped that it would lead to developing a theoretical predictive base to guide the search for new catalysts. This understanding allows one to develop a set of hierarchical models, from fundamental atomic-level ab-initio models to detailed engineering simulations of reactor systems, to direct the search for optimized, efficient catalyst systems. During the last two decades, the explosions of advanced surface analysis techniques have helped considerably to develop the building blocks for understanding various catalytic reactions. An effort to couple these theoretical and experimental advances to develop a set of hierarchical models to predict the nature of catalytic materials is a program entitled Catalysis-by-Design (CRD).'' In assessing the potential impacts of CBD on US industry, the key point to remember is that the value of the program lies in developing a novel methodology to search for new catalyst systems. Industrial researchers can then use this methodology to develop proprietary catalysts. Most companies involved in catalyst R D have two types of ongoing projects. The first type, what we call market-driven R D,'' are projects that support and improve upon a company's existing product lines. Project of the second type, technology-driven R D,'' are longer term, involve the development of totally new catalysts, and are initiated through scientists' research ideas. The CBD approach will impact both types of projects. However, this analysis indicates that the near-term impacts will be on market-driven'' projects. The conclusions and recommendations presented in this report were obtained by the authors through personal interviews with individuals involved in a variety of industrial catalyst development programs and through the three CBD workshops held in the summer of 1989. 34 refs., 7 figs., 7 tabs.

Fassbender, L L; Young, J K [Pacific Northwest Lab., Richland, WA (USA); Sen, R K [Sen (R.K.) and Associates, Washington, DC (USA)

1991-05-01T23:59:59.000Z

142

High-Spin Cobalt Hydrides for Catalysis  

SciTech Connect (OSTI)

Organometallic chemists have traditionally used catalysts with strong-field ligands that give low-spin complexes. However, complexes with a weak ligand field have weaker bonds and lower barriers to geometric changes, suggesting that they may lead to more rapid catalytic reactions. Developing our understanding of high-spin complexes requires the use of a broader range of spectroscopic techniques, but has the promise of changing the mechanism and/or selectivity of known catalytic reactions. These changes may enable the more efficient utilization of chemical resources. A special advantage of cobalt and iron catalysts is that the metals are more abundant and cheaper than those currently used for major industrial processes that convert unsaturated organic molecules and biofeedstocks into useful chemicals. This project specifically evaluated the potential of high-spin cobalt complexes for small-molecule reactions for bond rearrangement and cleavage reactions relevant to hydrocarbon transformations. We have learned that many of these reactions proceed through crossing to different spin states: for example, high-spin complexes can flip one electron spin to access a lower-energy reaction pathway for beta-hydride elimination. This reaction enables new, selective olefin isomerization catalysis. The high-spin cobalt complexes also cleave the C-O bond of CO2 and the C-F bonds of fluoroarenes. In each case, the detailed mechanism of the reaction has been determined. Importantly, we have discovered that the cobalt catalysts described here give distinctive selectivities that are better than known catalysts. These selectivities come from a synergy between supporting ligand design and electronic control of the spin-state crossing in the reactions.

Holland, Patrick L. [Yale University] [Yale University

2013-08-29T23:59:59.000Z

143

MRI of Heterogeneous Hydrogenation Reactions Using Parahydrogen Polarization  

SciTech Connect (OSTI)

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.

Burt, Scott R; Burt, Scott R.

2008-06-25T23:59:59.000Z

144

Allylation of acetanilides with allyl acetate under conditions of metal-complex catalysis combined with phase-transfer catalysis  

SciTech Connect (OSTI)

Acetanilides are alkylated at the nitrogen atom under the conditions of phase-transfer catalysis. For the case of the reaction of acetanilides with allyl acetate the authors showed that 2-alkenyl esters can be used for the alkylation of acetanilides under the conditions of phase-transfer catalysis in the presence of the complexes of zero valent palladium. N-Acetylskatole was obtained with a yield of 50% from N-allyl-2-bromoacetanilide by intramolecular cyclization in the presence of Od(OAc)/sub 2/ as catalyst.

Lebedev, S.A.; Leonova, Yu.P.; Berestova, S.S.; Petrov, E.S.

1988-10-20T23:59:59.000Z

145

Heterogeneous recurrence monitoring and control of nonlinear stochastic processes  

SciTech Connect (OSTI)

Recurrence is one of the most common phenomena in natural and engineering systems. Process monitoring of dynamic transitions in nonlinear and nonstationary systems is more concerned with aperiodic recurrences and recurrence variations. However, little has been done to investigate the heterogeneous recurrence variations and link with the objectives of process monitoring and anomaly detection. Notably, nonlinear recurrence methodologies are based on homogeneous recurrences, which treat all recurrence states in the same way as black dots, and non-recurrence is white in recurrence plots. Heterogeneous recurrences are more concerned about the variations of recurrence states in terms of state properties (e.g., values and relative locations) and the evolving dynamics (e.g., sequential state transitions). This paper presents a novel approach of heterogeneous recurrence analysis that utilizes a new fractal representation to delineate heterogeneous recurrence states in multiple scales, including the recurrences of both single states and multi-state sequences. Further, we developed a new set of heterogeneous recurrence quantifiers that are extracted from fractal representation in the transformed space. To that end, we integrated multivariate statistical control charts with heterogeneous recurrence analysis to simultaneously monitor two or more related quantifiers. Experimental results on nonlinear stochastic processes show that the proposed approach not only captures heterogeneous recurrence patterns in the fractal representation but also effectively monitors the changes in the dynamics of a complex system.

Yang, Hui, E-mail: huiyang@usf.edu; Chen, Yun [Complex Systems Monitoring, Modeling and Analysis Laboratory, University of South Florida, Tampa, Florida 33620 (United States)] [Complex Systems Monitoring, Modeling and Analysis Laboratory, University of South Florida, Tampa, Florida 33620 (United States)

2014-03-15T23:59:59.000Z

146

Frontiers in Catalysis Science and Engineering Seminar Series  

E-Print Network [OSTI]

THE CATALYTIC UPGRADE OF PYROLYSIS OIL IN VAPOR AND LIQUID PHASES Presented by... Daniel E. Resasco ·Douglas Engineering ·University of Oklahoma Abstract An effective approach to stabilize pyrolysis oil is conducting for Interfacial Reaction Engineering (CIRE) http://www.ou.edu/catalysis/ Center for Biomass Befining (CBR) http

147

Lithium Diisopropylamide-Mediated Ortholithiations: Lithium Chloride Catalysis  

E-Print Network [OSTI]

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

Collum, David B.

148

Frontiers in Catalysis Science and Engineering Seminar Series  

E-Print Network [OSTI]

Frontiers in Catalysis Science and Engineering Seminar Series On the role of hydrogen of Chemical & Biological Engineering ·University of Wisconsin - Madison Abstract Hydrogen is a frequent principles governing the role of hydrogen in a wide range of catalytic transformations begin to emerge

149

Overview of surface science and catalysis by Qifei Wu  

E-Print Network [OSTI]

surfaces: single crystal transition metals, metal nanoparticles (Au), metal oxides, sulfides, carbides: · Metcars are the better catalysts for HDS than the other metal carbide materials. · Metcars have better: Sulfides (RuS2), carbides (MoC, TiC) #12;Density Functional Theory in Catalysis Employ DFT to understand

150

Coherence delay augmented laser beam homogenizer  

DOE Patents [OSTI]

The geometrical restrictions on a laser beam homogenizer are relaxed by ug a coherence delay line to separate a coherent input beam into several components each having a path length difference equal to a multiple of the coherence length with respect to the other components. The components recombine incoherently at the output of the homogenizer, and the resultant beam has a more uniform spatial intensity suitable for microlithography and laser pantogography. Also disclosed is a variable aperture homogenizer, and a liquid filled homogenizer.

Rasmussen, P.; Bernhardt, A.

1993-06-29T23:59:59.000Z

151

NOTE: OPTIMAL NON-HOMOGENEOUS COMPOSITES FOR ...  

E-Print Network [OSTI]

NOTE: OPTIMAL NON-HOMOGENEOUS COMPOSITES FOR. DYNAMIC LOADING REVISITED. R. TAVAKOLI. 1. Problem formulation. Consider ? ? Rd (

R. Tavakoli

2012-10-02T23:59:59.000Z

152

Coherence delay augmented laser beam homogenizer  

DOE Patents [OSTI]

The geometrical restrictions on a laser beam homogenizer are relaxed by ug a coherence delay line to separate a coherent input beam into several components each having a path length difference equal to a multiple of the coherence length with respect to the other components. The components recombine incoherently at the output of the homogenizer, and the resultant beam has a more uniform spatial intensity suitable for microlithography and laser pantogography. Also disclosed is a variable aperture homogenizer, and a liquid filled homogenizer.

Rasmussen, Paul (Livermore, CA); Bernhardt, Anthony (Berkeley, CA)

1993-01-01T23:59:59.000Z

153

Experiments and analysis for an axially heterogeneous liquid-metal reactor assembly at the zero-power physics reactor  

SciTech Connect (OSTI)

Experiments in zero-power physics reactor 17 provided physics data for a full-scale axially heterogeneous 650-MW(electric) liquid-metal reactor. Measurements and analysis are reported for control rod worths, reaction rate distributions, gamma dose distributions, sodium void worths, and criticality. Agreement between measurement and calculation is generally satisfactory, but the axial heterogeneity did introduce analytical complications. Design-level calculation methods gave somewhat worse agreement with measurement than in previous homogeneous or radially heterogeneous assemblies.

Brumbach, S.B.; Collins, P.J. (Argonne National Lab., Idaho Falls, ID (USA))

1989-11-01T23:59:59.000Z

154

Heterogeneous electrocatalysis in porous cathodes of solid oxide fuel cells  

E-Print Network [OSTI]

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...

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

2014-01-01T23:59:59.000Z

155

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

SciTech Connect (OSTI)

Understanding chemical reactions requires the knowledge of the elementary steps of breaking and making bonds, and often a variety of experimental techniques are needed to achieve this goal. The initial steps occur on the femto- through picosecond time-scales, requiring the use of ultrafast spectroscopic methods, while the rate-limiting steps often occur more slowly, requiring alternative techniques. Ultrafast one and two-dimensional infrared and step-scan FTIR spectroscopies are used to investigate the photochemical reactions of four organometallic complexes. The analysis leads to a detailed understanding of mechanisms that are general in nature and may be applicable to a variety of reactions.

Sawyer, Karma Rae

2008-12-12T23:59:59.000Z

156

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

E-Print Network [OSTI]

is separating and reusing precious metal catalyst; therefore, it needs to be performed in a convenient platform. To figure out this problem, a biphasic system can be suggested in which one phase sequesters the solid catalyst and the other phase delivers...

Ahosseini, Azita

157

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

SciTech Connect (OSTI)

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.

Appy, David [Ames Laboratory; Lei, Huaping [Ames Laboratory; Han, Yong [Ames Laboratory; Wang, Cai-Zhuang [Ames Laboratory; Tringides, Michael C [Ames Laboratory; Shao, Dahai [Ames Laboratory; Kwolek, Emma J [Iowa State University; Evans, J W [Ames Laboratory; Thiel, P A [Ames Laboratory

2014-11-01T23:59:59.000Z

158

Pacific Northwest National Laboratory Catalysis Highlights for FY2007  

SciTech Connect (OSTI)

To reduce the nation’s dependence on imported oil, the U.S. Department of Energy (DOE) and other federal and private agencies are investing in understanding catalysis. This report focuses on catalysis research conducted by Pacific Northwest National Laboratory (PNNL) and its collaborators. Using sophisticated instruments in DOE’s Environmental Molecular Sciences Laboratory, a national scientific user facility, research was conducted to answer key questions related to the nation’s use of automotive fuels. Research teams investigated how hydrogen can be safely stored and efficiently released, critical questions to use this alternative fuel. Further, they are answering key questions to design molecular catalysts to control the transfer of hydrogen atoms, hydrides, and protons important to hydrogen production. In dealing with today’s fuels, researchers examined adsorption of noxious nitrous oxides in automotive exhaust. Beyond automotive fuel, researchers worked on catalysts to harness solar power. These catalysts include the rutile and anatase forms of titanium dioxide. Basic research was conducted on designing catalysts for these and other applications. Our scientists examined how to build catalysts with the desired properties atom by atom and molecule by molecule. In addition, this report contains brief descriptions of the outstanding accomplishments of catalysis experts at PNNL.

Garrett, Bruce C.

2007-11-15T23:59:59.000Z

159

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

SciTech Connect (OSTI)

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.

Wachs, Israel E.

2013-08-05T23:59:59.000Z

160

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

Broader source: Energy.gov (indexed) [DOE]

Lean NOx Catalysis l Chemistry l Reducing Agent Effects l Collaboration with LEP CRADA l Aging Studies Plasma Initiation - + Electron Avalanche e - e - e - e - e - e - e -...

Note: This page contains sample records for the topic "homogeneous catalysis heterogeneous" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


161

AQUEOUS HOMOGENEOUS REACTORTECHNICAL PANEL REPORT  

SciTech Connect (OSTI)

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.

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.

2010-12-03T23:59:59.000Z

162

Homogeneous catalysts in hypersonic combustion  

SciTech Connect (OSTI)

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.

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

1989-01-01T23:59:59.000Z

163

MORLEY RANK IN HOMOGENEOUS MODELS ALEXEI KOLESNIKOV  

E-Print Network [OSTI]

MORLEY RANK IN HOMOGENEOUS MODELS ALEXEI KOLESNIKOV AND G.V.N.G. KRISHNAMURTHI Abstract. We define an appropriate analog of the Morley rank in a totally transcendental homogeneous model with type diagram D. We-extensions of rank . This is surprising, because the proof of the statement in the first-order case depends heavily

Kolesnikov, Alexei

164

Monodisperse Platinum and Rhodium Nanoparticles as Model Heterogeneous Catalysts  

SciTech Connect (OSTI)

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.

Coble, Inger M

2008-08-15T23:59:59.000Z

165

Tandem Catalysis A Highly Efficient and Rapid Approach to Synthetic Elaboration  

E-Print Network [OSTI]

diiodide catalyzed Mukaiyama Michael-aldol reactions C.) Zirconium catalyzed synthesis of !-cyanohydrins D and rhodium catalyzed annulation. B.) Cobalt catalyzed annulation and cycloaddition C.) Rapid synthesis of pyrroles and furans D.) Organocatalytic / Lewis acid tandem catalysis 5.) Conclusions Tandem catalysis

Stoltz, Brian M.

166

Inorganic Chemistry in Hydrogen Storage and Biomass Catalysis  

SciTech Connect (OSTI)

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.

Thorn, David [Los Alamos National Laboratory

2012-06-13T23:59:59.000Z

167

Microwaves and Chemistry: The Catalysis of an Exciting Marriage  

E-Print Network [OSTI]

. Product distrihution of microwave catalysis of carbon dioxide and water. Product Relative % yield Methane 55.1 Methanol 5.5 Acetone 4.7 C J alcohols 5.8 C 4 alcohols 28.4 o.5,------------------ 0.4 'C v >= 0.3 !i ;:I '" 0.2 &1... our first major success in cracking methane to ethylene and hydrogen [1,2], lhe destruction of chlorinated hydrocarbons [3,4], the hydrodesulfurization of hydrocracked pitch [5], and the microwave treatment of some Alberta oil sands and bitumens...

Wan, J.

168

Catalysis Working Group Meeting: June 2014 | Department of Energy  

Broader source: Energy.gov (indexed) [DOE]

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:1 First Use of Energy for All Purposes (Fuel and Nonfuel),Feet) Year Jan Feb Mar Apr May Jun Jul(Summary) "ofEarly Career Scientists' ResearchTheMarketing,Energy-ChevronSeveral salesCarolyn L.in aDataThe Catalysis

169

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

E-Print Network [OSTI]

infrared spectrum of the irradiated propane ice after heatinginfrared spectrum obtained for irradiated propane ices after controlled heatingsubstrate after heating to 300 K. The infrared spectrum

Kaiser, Ralf I.

2010-01-01T23:59:59.000Z

170

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

SciTech Connect (OSTI)

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.

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

2010-03-16T23:59:59.000Z

171

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

E-Print Network [OSTI]

1 Electrospun Polyethylene Oxide/Cellulose Nanocrystal Composite 2 Nanofibrous Mats(acrylic acid) (PAA),14 polyethylene oxide (PEO),15 poly(lactic 57acid) (PLA),16,17 polystyrene (PS),18 was successfully used 9 to fabricate polyethylene oxide/cellulose nanocrystal (PEO/ 10 CNC) composite nanofibrous

172

Multiscale strength homogenization : application to shale nanoindentation  

E-Print Network [OSTI]

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 ...

Gathier, Benjamin

2008-01-01T23:59:59.000Z

173

Producing tritium in a homogenous reactor  

DOE Patents [OSTI]

A method and apparatus are described for the joint production and separation of tritium. Tritium is produced in an aqueous homogenous reactor and heat from the nuclear reaction is used to distill tritium from the lower isotopes of hydrogen.

Cawley, William E. (Richland, WA)

1985-01-01T23:59:59.000Z

174

An experimental investigation of viscous fingering in heterogeneous porous media  

SciTech Connect (OSTI)

The growth of viscous fingers in heterogeneous porous media was examined using flow visualization experiments in four different glass bead packs with different permeability heterogeneities: a uniform permeability model, one with two equal-width layers in the flow direction, one with a thin, high permeability streak in the flow direction, and one with blocks of different permeabilities. The experiments were compared with numerical simulations, paying particular attention to finger growth mechanisms, finger sizes and locations, and number of fingers. In near-homogeneous model displacements, fingers were observed to grow through the mechanisms of spreading, splitting, shielding, and coalescence. In all experiments, shielding and coalescence acted to reduce the number of fingers as flow progressed. Analysis of pressure distributions in and around fingers indicates that viscous crossflow was the driving force for the finger growth mechanisms. Simulations of the experiments yielded finger patterns similar to those observed in the experiments. The general agreement over a variety of mobility ratios and rates indicates that the simulator used captures the essential features of the physics of finger growth. In heterogeneous permeability fields, locations of fingers were largely determined by the pattern of heterogeneity. In the model with two thick layers and the model with blocks of different permeabilities, a pattern of viscous fingers was superimposed on the fronts. The model with a thin, high permeability streak showed very little viscous fingering because the width of the layer was small. In the heterogeneous cases, simulations yielded finger patterns remarkably similar to those observed in experiments. In particular, simulations reproduced the concept of viscous fingers overlain on flow affected by permeability heterogeneity.

Brock, D.C.

1991-01-01T23:59:59.000Z

175

A Note on KKT Points of Homogeneous Programs 1'  

E-Print Network [OSTI]

A Note on KKT Points of Homogeneous Programs 1'. Y. B. Zhao 2 and D. Li 3. Abstract. Homogeneous programming is an important class of optimization ...

2005-07-11T23:59:59.000Z

176

Microgrids and Heterogeneous Security, Quality, Reliability, andAvailability  

SciTech Connect (OSTI)

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.

Marnay, Chris

2007-01-31T23:59:59.000Z

177

Metal Carbonyl-Hydrosilane Reactions and Hydrosilation Catalysis  

SciTech Connect (OSTI)

Manganese carbonyl complexes serve as hydrosilation precatalysts for selectively transforming a carbonyl group into a siloxy methylene or a fully reduced methylene group. Substrates of interest include (1) aldehydes, ketones, carboxylic acids, silyl esters, and esters, and (2) their organometallic acyl counterparts. Three relevant catalytic reactions are shown. Two types of manganese precatalysts have been reported: (a) alkyl and acyl complexes (L)(C0){sub 4}MnR [L = CO, PPh{sub 3}; R = COCH{sub 3}, COPh, CH{sub 3}] and (b) halides (CO){sub 5}MnX and [(CO){sub 4}MnX]{sub 2} (X = Br, I). The former promote hydrosilation and deoxygenation catalysis; the latter promote dehydrogenative silation of alcohols and carboxylic acids as well as hydrosilation and deoxygenation of some metallocarboxylic acid derivatives. In every case studied, these Mn precatalysts are far more reactive or selective than traditional Rh(I) precatalysts.

Cutler, A. R.

2001-04-14T23:59:59.000Z

178

Spontaneous generation of local CP violation and inverse magnetic catalysis  

E-Print Network [OSTI]

In the chiral symmetric phase, the polarized instanton--anti-instanton molecule pairing induces a nontrivial repulsive interaction in the iso-scalar axial-vector channel. As a consequence, one unusual property is observed that in the chiral restoration phase, there is a first order phase transition for the spontaneous generation of local CP violation and chiral imbalance. Furthermore, it is found that external magnetic fields will lower the critical temperature for the local CP-odd phase transition and catalyze the chiral imbalance, which destroys the chiral condensate with pairing quarks between different chiralities. A reasonable strength of the repulsive interaction in the iso-scalar axial-vector channel can naturally explain the inverse magnetic catalysis around the critical temperature under external magnetic fields.

Lang Yu; Hao Liu; Mei Huang

2014-09-14T23:59:59.000Z

179

Fluid Interface Reactions, Structures and Transport (FIRST) Center EFRC Director: David J. Wesolowski  

E-Print Network [OSTI]

technologies, including electrical energy storage (batteries, supercapacitors) and heterogeneous catalysis solar energy utilization, energy storage (batteries and supercapacitors), heterogeneous catalysis

180

Studies toward biomimetic claisen condensation using nucleic acid templates and ribozyme catalysis  

E-Print Network [OSTI]

Many different experimental approaches were attempted to achieve carbon-carbon bond formation by nucleic acid template-directed reactions and ribozyme catalysis as potential lipid synthesizing machineries in the RNA world. A novel biomimetic...

Ryu, Youngha

2005-08-29T23:59:59.000Z

Note: This page contains sample records for the topic "homogeneous catalysis heterogeneous" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


181

Combined Catalysis and Optical Screening for High Throughput Discovery of Solar Fuels Catalysts  

E-Print Network [OSTI]

Combined Catalysis and Optical Screening for High Throughput Discovery of Solar Fuels Catalysts J,b a Joint Center for Artificial Photosynthesis, California Institute of Technology, Pasadena, California 91125, USA b Engineering Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720

Faraon, Andrei

182

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

E-Print Network [OSTI]

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, ...

Anderson, Brian J.

183

Chimera states in heterogeneous networks  

E-Print Network [OSTI]

Chimera states in networks of coupled oscillators occur when some fraction of the oscillators synchronise with one another, while the remaining oscillators are incoherent. Several groups have studied chimerae in networks of identical oscillators, but here we study these states in a heterogeneous model for which the natural frequencies of the oscillators are chosen from a distribution. We obtain exact results by reduction to a finite set of differential equations. We find that heterogeneity can destroy chimerae, destroy all states except chimerae, or destabilise chimerae in Hopf bifurcations, depending on the form of the heterogeneity.

Carlo R. Laing

2008-12-17T23:59:59.000Z

184

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

SciTech Connect (OSTI)

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)

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)

2014-09-30T23:59:59.000Z

185

Final Report on Kokes Awards for the 20th North American Catalysis Society Meeting  

SciTech Connect (OSTI)

This Final Report describes how the Kokes Awards program was carried out for the 2007 meeting with regard to selection of students and disbursement of funds received from DOE and other sources. The objective of the Richard J. Kokes Travel Award program of the American Catalysis Society is to encourage graduate students to attend and participate meaningfully in the biennial North American Catalysis Society Meeting.

Wong, Michael S.

2008-01-01T23:59:59.000Z

186

ANDREA BRAIDES Homogenization of Lattice Systems  

E-Print Network [OSTI]

) Identification: identify u with some continuous parameter (e.g., its piecewise-constant interpolation; a sum(ui, uj) indexed on a scaled lattice (e.g., Zd ) Identification: identify u with some continuous.Braides: Homogenization of Lattice Systems #12;BINARY SYSTEMS: Continuous limits of ferromagnetic energies Bulk scaling

Braides, Andrea

187

Sensitivity Analysis of Combustion Timing of Homogeneous  

E-Print Network [OSTI]

to predict the start of combustion in a homogeneous charge compression ignition (HCCI) engine. Qualitative and quantitative information on the individual effects of fuel and exhaust gas recirculation on the HCCI combustion-injection gasoline HCCI engine, we find that temperature is the dominant factor in determining the start

Stefanopoulou, Anna

188

A Homogenized Energy Framework for Ferromagnetic Hysteresis  

E-Print Network [OSTI]

energy relations at the mesoscopic or lattice level based on the assumption that magnetic momentsA Homogenized Energy Framework for Ferromagnetic Hysteresis Ralph C. Smith Marcelo J. Dapino Center or spins are restricted to two orientations. Direct minimization of the Gibbs energy yields local average

189

Optimal Design of Heterogeneous Materials  

E-Print Network [OSTI]

are granular media, soils, polycrystals, sandstone, wood, bone, lungs, blood, animal and plant tissue, cell, electromagnetic, and mechanical properties of heterogeneous materials has a long and venerable history, attracting

Torquato, Salvatore

190

Portable performance on heterogeneous architectures  

E-Print Network [OSTI]

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 ...

Phothilimthana, Phitchaya Mangpo

191

Density Functional Theory in Surface Chemistry and Catalysis  

SciTech Connect (OSTI)

Recent advances in the understanding of reactivity trends for chemistry at transition metal surfaces have enabled in silico design of heterogeneous catalysts in a few cases. Current status of the field is discussed with an emphasis on the role of coupling between theory and experiment and future challenges.

Norskov, Jens

2011-05-19T23:59:59.000Z

192

Quantum Memory with a controlled homogeneous splitting  

E-Print Network [OSTI]

We propose a quantum memory protocol where a input light field can be stored onto and released from a single ground state atomic ensemble by controlling dynamically the strength of an external static and homogeneous field. The technique relies on the adiabatic following of a polaritonic excitation onto a state for which the forward collective radiative emission is forbidden. The resemblance with the archetypal Electromagnetically-Induced-Transparency (EIT) is only formal because no ground state coherence based slow-light propagation is considered here. As compared to the other grand category of protocols derived from the photon-echo technique, our approach only involves a homogeneous static field. We discuss two physical situations where the effect can be observed, and show that in the limit where the excited state lifetime is longer than the storage time, the protocols are perfectly efficient and noise-free. We compare the technique to other quantum memories, and propose atomic systems where the experiment c...

Hétet, G; Chanelière, T

2013-01-01T23:59:59.000Z

193

On the energy of homogeneous cosmologies  

E-Print Network [OSTI]

An energy for the homogeneous cosmological models is presented. More specifically, using an appropriate natural prescription, we find the energy within any region with any gravitational source for a large class of gravity theories--namely those with a tetrad description--for all 9 Bianchi types. Our energy is given by the value of the Hamiltonian with homogeneous boundary conditions; this value vanishes for all regions in all Bianchi class A models, and it does not vanish for any class B model. This is so not only for Einstein's general relativity but, moreover, for the whole 3-parameter class of tetrad-teleparallel theories. For the physically favored one parameter subclass, which includes the teleparallel equivalent of Einstein's theory as an important special case, the energy for all class B models is, contrary to expectation, negative.

James M. Nester; Lau Loi So; T. Vargas

2008-03-23T23:59:59.000Z

194

Renewal-anomalous-heterogeneous files  

E-Print Network [OSTI]

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.

Ophir Flomenbom

2010-08-13T23:59:59.000Z

195

Molecular-level Design of Heterogeneous Chiral Catalysts  

SciTech Connect (OSTI)

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.

Gellman, Andrew John [Carnegie Mellon University; Sholl, David S. [Georgia Institute of Technology; Tysoe, Wilfred T. [University of Wisconsin - Milwaukee; Zaera, Francisco [University of California at Riverside

2013-04-28T23:59:59.000Z

196

Studies of Immobilized Homogeneous Metal Catalysts on Silica Supports  

SciTech Connect (OSTI)

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.

Keith James Stanger

2003-05-31T23:59:59.000Z

197

Evolution of the Surface Science of Catalysis from Single Crystals to Metal Nanoparticles under Pressure  

SciTech Connect (OSTI)

Vacuum studies of metal single crystal surfaces using electron and molecular beam scattering revealed that the surface atoms relocate when the surface is clean (reconstruction) and when it is covered by adsorbates (adsorbate induced restructuring). It was also discovered that atomic steps and other low coordination surface sites are active for breaking chemical bonds (H-H, O=O, C-H, C=O and C-C) with high reaction probability. Investigations at high reactant pressures using sum frequency generation (SFG)--vibrational spectroscopy and high pressure scanning tunneling microscopy (HPSTM) revealed bond breaking at low reaction probability sites on the adsorbate-covered metal surface, and the need for adsorbate mobility for continued turnover. Since most catalysts (heterogeneous, enzyme and homogeneous) are nanoparticles, colloid synthesis methods were developed to produce monodispersed metal nanoparticles in the 1-10 nm range and controlled shapes to use them as new model catalyst systems in two-dimensional thin film form or deposited in mesoporous three-dimensional oxides. Studies of reaction selectivity in multipath reactions (hydrogenation of benzene, cyclohexene and crotonaldehyde) showed that reaction selectivity depends on both nanoparticle size and shape. The oxide-metal nanoparticle interface was found to be an important catalytic site because of the hot electron flow induced by exothermic reactions like carbon monoxide oxidation.

Somorjai, Gabor A.; Park, Jeong Y.

2008-03-06T23:59:59.000Z

198

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

SciTech Connect (OSTI)

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.

Abhaya Datye

2010-07-02T23:59:59.000Z

199

New multilateral well architecture in heterogeneous reservoirs  

E-Print Network [OSTI]

. The performance of new multilateral well in heterogeneous reservoirs is studied, and that is compared with vertical well architecture also. In order to study the productivity of new multilateral wells, we use a numerical simulation method to set up heterogeneous...

Jia, Hongqiao

2004-09-30T23:59:59.000Z

200

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

SciTech Connect (OSTI)

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.

Sun, Jie, E-mail: jie.sun@chalmers.se; Lindvall, Niclas; Yurgens, August [Quantum Device Physics Laboratory, Department of Microtechnology and Nanoscience, Chalmers University of Technology, SE-41296 Gothenburg (Sweden); Nam, Youngwoo [Quantum Device Physics Laboratory, Department of Microtechnology and Nanoscience, Chalmers University of Technology, SE-41296 Gothenburg (Sweden); Department of Physics and Astronomy, Seoul National University, Seoul 151-747 (Korea, Republic of); Cole, Matthew T. [Electrical Engineering Division, Department of Engineering, University of Cambridge, 9 JJ Thomson Avenue, CB3 0FA Cambridge (United Kingdom); Teo, Kenneth B. K. [AIXTRON Nanoinstruments Ltd., Swavesey, CB24 4FQ Cambridge (United Kingdom); Woo Park, Yung [Department of Physics and Astronomy, Seoul National University, Seoul 151-747 (Korea, Republic of)

2014-04-14T23:59:59.000Z

Note: This page contains sample records for the topic "homogeneous catalysis heterogeneous" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


201

High Throughput Sample Preparation and Analysis for DNA Sequencing, PCR and Combinatorial Screening of Catalysis Based on Capillary Array Technique  

SciTech Connect (OSTI)

Sample preparation has been one of the major bottlenecks for many high throughput analyses. The purpose of this research was to develop new sample preparation and integration approach for DNA sequencing, PCR based DNA analysis and combinatorial screening of homogeneous catalysis based on multiplexed capillary electrophoresis with laser induced fluorescence or imaging UV absorption detection. The author first introduced a method to integrate the front-end tasks to DNA capillary-array sequencers. protocols for directly sequencing the plasmids from a single bacterial colony in fused-silica capillaries were developed. After the colony was picked, lysis was accomplished in situ in the plastic sample tube using either a thermocycler or heating block. Upon heating, the plasmids were released while chromsomal DNA and membrane proteins were denatured and precipitated to the bottom of the tube. After adding enzyme and Sanger reagents, the resulting solution was aspirated into the reaction capillaries by a syringe pump, and cycle sequencing was initiated. No deleterious effect upon the reaction efficiency, the on-line purification system, or the capillary electrophoresis separation was observed, even though the crude lysate was used as the template. Multiplexed on-line DNA sequencing data from 8 parallel channels allowed base calling up to 620 bp with an accuracy of 98%. The entire system can be automatically regenerated for repeated operation. For PCR based DNA analysis, they demonstrated that capillary electrophoresis with UV detection can be used for DNA analysis starting from clinical sample without purification. After PCR reaction using cheek cell, blood or HIV-1 gag DNA, the reaction mixtures was injected into the capillary either on-line or off-line by base stacking. The protocol was also applied to capillary array electrophoresis. The use of cheaper detection, and the elimination of purification of DNA sample before or after PCR reaction, will make this approach an attractive alternative to current methods for genetic analysis and disease diagnosis.

Yonghua Zhang

2002-05-27T23:59:59.000Z

202

Homogeneous catalyst formulations for methanol production  

DOE Patents [OSTI]

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.

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

1991-02-12T23:59:59.000Z

203

Homogeneous catalyst formulations for methanol production  

DOE Patents [OSTI]

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.

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

1990-01-01T23:59:59.000Z

204

KINETICS, CATALYSIS, AND REACTION ENGINEERING Nonthermal Plasma Reactions of Dilute Nitrogen Oxide Mixtures  

E-Print Network [OSTI]

for the conversion of nitrogen oxides,1,2,4-10 sulfur dioxide,11 and volatile organic car- bons.12 Despite itsKINETICS, CATALYSIS, AND REACTION ENGINEERING Nonthermal Plasma Reactions of Dilute Nitrogen Oxide Mixtures: NOx in Nitrogen Gui-Bing Zhao, Xudong Hu, Man-Chung Yeung, Ovid A. Plumb,§ and Maciej Radosz

Yeung, Man-Chung

205

Enantioselective Organocatalytic Indole Alkylations. Design of a New and Highly Effective Chiral Amine for Iminium Catalysis  

E-Print Network [OSTI]

structural motifs of established value in medicinal chemistry or complex target synthesis. In this regard the capacity of iminium catalysis to mediate the enantioselective coupling of pyrroles and R, -unsaturated alde nucleophiles. Despite struc- tural similarities, it has long been established7 that the pyrrole -system

MacMillan, David W. C.

206

Argonne National Laboratory Chemical Engineering Division Water-gas shift catalysis  

E-Print Network [OSTI]

Argonne National Laboratory Chemical Engineering Division Water-gas shift catalysis Sara Yu Choung Engineering Division Argonne National Laboratory Hydrogen, Fuel Cells, and Infrastructure Technologies 2003 Merit Review Berkeley, CA May 19-22, 2003 #12;Argonne National Laboratory Chemical Engineering Division

207

Applied Catalysis A: General 254 (2003) 97106 Photoionization detection (PID) as a high throughput  

E-Print Network [OSTI]

Applied Catalysis A: General 254 (2003) 97­106 Photoionization detection (PID) as a high throughput 2002 Abstract A versatile photoionization detection (PID) system has been developed to rapidly screen libraries of catalytic materials. The PID approach involves the use of an appropriately selected dc

Senkan, Selim M.

208

Enzyme-Like Catalysis of the Nazarov Cyclization by Supramolecular Encapsulation  

SciTech Connect (OSTI)

A primary goal in the design and synthesis of molecular hosts has been the selective recognition and binding of a variety of guests using non-covalent interactions. Supramolecular catalysis, which is the application of such hosts towards catalysis, has much in common with many enzymatic reactions, chiefly the use of both spatially appropriate binding pockets and precisely oriented functional groups to recognize and activate specific substrate molecules. Although there are now many examples which demonstrate how selective encapsulation in a host cavity can enhance the reactivity of a bound guest, all have failed to reach the degree of increased reactivity typical of enzymes. We now report the catalysis of the Nazarov cyclization by a self-assembled coordination cage, a carbon-carbon bond-forming reaction which proceeds under mild, aqueous conditions. The acceleration in this system is over a million-fold, and represents the first example of supramolecular catalysis that achieves the level of rate enhancement comparable to that observed in several enzymes. We explain the unprecedented degree of rate increase as due to the combination of (a) preorganization of the encapsulated substrate molecule, (b) stabilization of the transition state of the cyclization by constrictive binding, and (c) increase in the basicity of the complexed alcohol functionality.

Hastings, Courtney; Pluth, Michael; Bergman, Robert; Raymond, Kenneth

2010-03-29T23:59:59.000Z

209

High-throughput metal nanoparticle catalysis by pulsed laser ablation Selim Senkan a,*, Michael Kahn a  

E-Print Network [OSTI]

High-throughput metal nanoparticle catalysis by pulsed laser ablation Selim Senkan a,*, Michael online 18 July 2006 Abstract A high-throughput pulsed laser ablation (HT-PLA) system was developed-TEM) and energy dispersive X-ray (EDX) spectroscopy, respectively. The supported nanoparticles created by HT

Senkan, Selim M.

210

Journal of Catalysis 225 (2004) 300306 www.elsevier.com/locate/jcat  

E-Print Network [OSTI]

shown that methanol can be produced by using N2O as the oxidant, rather than O2 [1­3]. More recently framework positions and ex- traframework Fe) can be used to produce methanol from CH4 and N2O. Above 523 KJournal of Catalysis 225 (2004) 300­306 www.elsevier.com/locate/jcat Methanol formation on Fe

Bell, Alexis T.

211

Catalysis Today 53 (1999) 433441 New insights into methanol synthesis catalysts from X-ray absorption  

E-Print Network [OSTI]

O and Cr2O3 mixtures and produced methanol in low yields from CO­H2 mixtures at high temperatures (593Catalysis Today 53 (1999) 433­441 New insights into methanol synthesis catalysts from X a consistent structural picture of methanol synthesis catalysts. Copper metal is the principal Cu species

Iglesia, Enrique

212

Tensor Rank and Stochastic Entanglement Catalysis for Multipartite Pure States  

E-Print Network [OSTI]

The tensor rank (also known as generalized Schmidt rank) of multipartite pure states plays an important role in the study of entanglement classifications and transformations. We employ powerful tools from the theory of homogeneous polynomials to investigate the tensor rank of symmetric states such as the tripartite state $\\ket{W_3}=\\tfrac{1}{\\sqrt{3}}(\\ket{100}+\\ket{010}+\\ket{001})$ and its $N$-partite generalization $\\ket{W_N}$. Previous tensor rank estimates are dramatically improved and we show that (i) three copies of $\\ket{W_3}$ has rank either 15 or 16, (ii) two copies of $\\ket{W_N}$ has rank $3N-2$, and (iii) $n$ copies of $\\ket{W_N}$ has rank O(N). A remarkable consequence of these results is that certain multipartite transformations, impossible even probabilistically, can become possible when performed in multiple copy bunches or when assisted by some catalyzing state. This effect is impossible for bipartite pure states.

Lin Chen; Eric Chitambar; Runyao Duan; Zhengfeng Ji; Andreas Winter

2010-11-10T23:59:59.000Z

213

Spatial homogenization for plate-type critical assemblies. [LMFBR  

SciTech Connect (OSTI)

Standard calculational models of plate-type LMFBR critical assemblies do not explicitly represent individual plates. Instead, detailed plate-by-plate calculations are performed only for each representative cell type, and homogenized cross sections are defined by flux-volume weighting of individual plate cross sections. Subsequent reactor calculations are performed by modeling each cell type with homogenized cross sections. The homogenized cross sections are sensitive to the manner in which the cell leakage is modeled. The intent of this paper is to present a method of representing the cell leakage which results in more accurate homogenized cross sections than the methods presently in use.

Rempe, K.R.; Smith, K.S.

1983-01-01T23:59:59.000Z

214

Optimization Online - Note: Optimal non-homogeneous composites ...  

E-Print Network [OSTI]

Aug 29, 2012 ... Note: Optimal non-homogeneous composites for dynamic loading revisited. Tavakoli Rouhollah (rtavakoli ***at*** sharif.ir). Abstract: The ...

Tavakoli Rouhollah

2012-08-29T23:59:59.000Z

215

A Homogeneous Model for P0 and P? Nonlinear Complementarity ...  

E-Print Network [OSTI]

to P0 CPs starting at a positive point near the central trajectory and does not .... the trajectory induced by the homogeneous model is discussed as an essential.

2005-05-01T23:59:59.000Z

216

Towards Realization of Computational Homogenization in Practice1  

E-Print Network [OSTI]

demonstrate how to utilize ABAQUS existing facilities to develop analysis attributes required for solving homogenization technologies have been successfully verified and validated; and while industry have abandoned in

Fish, Jacob

217

Davydov's Solitons in a Homogeneous Nucleotide Chain  

E-Print Network [OSTI]

Charge transfer in homogeneous nucleotide chains is modeled on the basis of Holstein Hamiltonian. The path length of Davydov solitons in these chains is being studied. It is shown that in a dispersionless case, when the soliton velocity V is small, the path length grows exponentially as V decreases. In this case the state of a moving soliton is quasisteady. In the presence of dispersion determined by the dependence $\\Omega^2 = \\Omega_0^2 + V_0^2\\kappa^2$ \\, the path length in the region 0 V_0 the soliton motion is accompanied by emission of phonons which leads to a finite path length of a soliton. The latter tends to infinity as $V \\rightarrow V_0 + 0$ and $V \\rightarrow \\infty$. The presence of dissipation leads to a finite soliton path length. An equilibrium velocity of soliton in an external electric field is calculated. It is shown that there is a maximum intensity of an electric field at which a steady motion of a soliton is possible. The soliton mobility is calculated for the stable or ohmic brunch.

Lakhno, Victor D

2013-01-01T23:59:59.000Z

218

Phase Transformations in Heterogeneous Steels  

E-Print Network [OSTI]

development of mi- crostructure in chemically heterogeneous alloys using the above model as a basis. 21 REFERENCES 1. G. J. Davies: Solidification and Castings, Applied Science Publishers, London, 1973. 2. M. C. Flemings: Solidification Processing, Mc... , Oxford, Pt. 1, 2nd ed., 1975. 51. M. Hillert: Acta Met., 1953, vol. 1, p. 764. 52. H. K. D. H. Bhadeshia: Metal Science, 1982, vol. 16, p. 159. 53. BISRA, Special Report no. 56, Chapman and Hall Ltd., London, 1956. 54. C. J. Shiflet, J. R. Bradley and H...

Khan, Shahid Amin

1990-05-08T23:59:59.000Z

219

Modelling long-distance seed dispersal in heterogeneous landscapes.  

SciTech Connect (OSTI)

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.

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

2008-01-01T23:59:59.000Z

220

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

E-Print Network [OSTI]

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 ...

Goldman, Peter John

2013-01-01T23:59:59.000Z

Note: This page contains sample records for the topic "homogeneous catalysis heterogeneous" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


221

DEFLECTION OF A HETEROGENEOUS WIDE-BEAM UNDER UNIFORM PRESSURE LOAD  

SciTech Connect (OSTI)

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.

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

2014-07-01T23:59:59.000Z

222

Heterogeneous Systems Testing Techniques: An Exploratory Survey.  

E-Print Network [OSTI]

??Heterogeneous systems comprising sets of inherent subsystems are challenging to integrate. In particular, testing for interoperability and conformance is a challenge. Furthermore, the complexities of… (more)

Ghazi, Ahmad; Petersen, Kai

2015-01-01T23:59:59.000Z

223

Chimera: Hypertext for Heterogeneous Software Environments  

E-Print Network [OSTI]

Chimera: Hypertext for Heterogeneous Software Environments Kenneth M. Anderson, Richard N. Taylor the approach and presents an architecture which supports it. Experience with the Chimera prototype and its

Whitehead, James

224

An investigation of homogeneous and heterogeneous sonochemistry for the destruction of hazardous substances. Progress report, 1996--1997  

SciTech Connect (OSTI)

'The primary objective of this research project is to acquire a deeper fundamental knowledge of acoustic cavitation and cavitation chemistry, and in doing so, to ascertain how ultrasonic irradiation can be more effectively applied to environmental problems. Four on-going projects will be described in this progress report, The first project is the destruction of carbofuran in a Near-Field Acoustical Processor (NAP), and the hydrodynamic characterization of the reactor. The second project is a comprehensive study of how ultrasonic frequency influences sonochemical reaction rates; the substrate it, the preliminary portion of this study has been hydrogen peroxide formation. The third project in progress is destruction of four polychlorinated biphenyls at 20 kHz. Work so far has been at 20 kHz, but the most significant portion of this project will involve a multi-frequency (ultrasonic frequency) study. Finally, the destruction of a pesticide, dichlorvos, during sonication at 500 kHz will be described. Preliminary work during the first year has emphasized determination of kinetics; further work (years 2--3) will be focused upon closing mass balances and identifying transformation products.'

Hua, I.

1997-01-01T23:59:59.000Z

225

Th/U-233 multi-recycle in pressurized water reactors : feasibility study of multiple homogeneous and heterogeneous assembly designs.  

SciTech Connect (OSTI)

The use of thorium in current or advanced light water reactors (LWRs) has been of interest in recent years. These interests have been associated with the need to increase nuclear fuel resources and the perceived non-proliferation advantages of the utilization of thorium in the fuel cycle. Various options have been considered for the use of thorium in the LWR fuel cycle. The possibility for thorium utilization in a multi-recycle system has also been considered in past literature, primarily because of the potential for near breeders with Th/U-233 in the thermal energy range. The objective of this study is to evaluate the potential of Th/U-233 fuel multi-recycle in current LWRs, focusing on pressurized water reactors (PWRs). Approaches for sustainable multi-recycle without the need for external fissile material makeup have been investigated. The intent is to obtain a design that allows existing PWRs to be used with minimal modifications.

Yun, D.; Taiwo, T. A.; Kim, T. K.; Mohamed, A.; Nuclear Engineering Division

2010-10-01T23:59:59.000Z

226

Heterogeneous Reburning By Mixed Fuels  

SciTech Connect (OSTI)

Recent studies of heterogeneous reburning, i.e., reburning involving a coal-derived char, have elucidated its variables, kinetics and mechanisms that are valuable to the development of a highly efficient reburning process. Young lignite chars contain catalysts that not only reduce NO, but they also reduce HCN that is an important intermediate that recycles to NO in the burnout zone. Gaseous CO scavenges the surface oxides that are formed during NO reduction, regenerating the active sites on the char surface. Based on this mechanistic information, cost-effective mixed fuels containing these multiple features has been designed and tested in a simulated reburning apparatus. Remarkably high reduction of NO and HCN has been observed and it is anticipated that mixed fuel will remove 85% of NO in a three-stage reburning process.

Anderson Hall

2009-03-31T23:59:59.000Z

227

Task and Machine Heterogeneities: Higher Moments Matter  

E-Print Network [OSTI]

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

Maciejewski, Anthony A.

228

Chimera: Hypermedia for Heterogeneous Software Development Environments  

E-Print Network [OSTI]

1 of 31 Chimera: Hypermedia for Heterogeneous Software Development Environments Abstract Emerging of "Chimera: Hypertext for Heterogeneous Software Environments," which appeared in the proceedings of ECHT'94 the approach employed by the Chimera open hypermedia system to address this research area, and also serves

Whitehead, James

229

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

SciTech Connect (OSTI)

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.

James F. Haw

2008-06-28T23:59:59.000Z

230

At tank Low Activity Feed Homogeneity Analysis Verification  

SciTech Connect (OSTI)

This report evaluates the merit of selecting sodium, aluminum, and cesium-137 as analytes to indicate homogeneity of soluble species in low-activity waste (LAW) feed and recommends possible analytes and physical properties that could serve as rapid screening indicators for LAW feed homogeneity. The three analytes are adequate as screening indicators of soluble species homogeneity for tank waste when a mixing pump is used to thoroughly mix the waste in the waste feed staging tank and when all dissolved species are present at concentrations well below their solubility limits. If either of these conditions is violated, then the three indicators may not be sufficiently chemically representative of other waste constituents to reliably indicate homogeneity in the feed supernatant. Additional homogeneity indicators that should be considered are anions such as fluoride, sulfate, and phosphate, total organic carbon/total inorganic carbon, and total alpha to estimate the transuranic species. Physical property measurements such as gamma profiling, conductivity, specific gravity, and total suspended solids are recommended as possible at-tank methods for indicating homogeneity. Indicators of LAW feed homogeneity are needed to reduce the U.S. Department of Energy, Office of River Protection (ORP) Program's contractual risk by assuring that the waste feed is within the contractual composition and can be supplied to the waste treatment plant within the schedule requirements.

DOUGLAS, J.G.

2000-09-28T23:59:59.000Z

231

Structural and Energetic Heterogeneity in Protein Folding  

E-Print Network [OSTI]

A general theoretical framework is developed using free energy functional methods to understand the effects of heterogeneity in the folding of a well-designed protein. Native energetic heterogeneity arising from non-uniformity in native stability, as well as entropic heterogeneity intrinsic to the topology of the native structure are both investigated as to their impact on the folding free energy landscape and resulting folding mechanism. Given a minimally frustrated protein, both structural and energetic heterogeneity lower the thermodynamic barrier to folding, and designing in sufficient heterogeneity can eliminate the barrier at the folding transition temperature. Sequences with different distributions of stability throughout the protein and correspondingly different folding mechanisms may still be good folders to the same structure. This theoretical framework allows for a systematic study of the coupled effects of energetics and topology in protein folding, and provides interpretations and predictions for future experiments which may investigate these effects.

Steven S. Plotkin; Jose N. Onuchic

2000-09-27T23:59:59.000Z

232

Comparisons of empirical viscous-fingering models and their calibration for heterogeneous problems  

SciTech Connect (OSTI)

This paper reviews the formulation and parameters for three principal empirical viscous-fingering models: the Kovl, Todd and Longstaff, and Fayers methods. All three methods give similar levels of accuracy when compared with linear homogeneous experiments, but they differ in performance in 2D applications. This arises from differences in the formulation of the total mobility terms. The superiority of the Todd and Longstaff and Fayers methods is demonstrated for 2D and gravity-influenced flows by comparison with experiments and high-resolution simulation. The use of high-resolution simulation to calibrate empirical models in a systematic manner is described. Results from detailed simulation demonstrate the sensitivity of empirical model parameters to viscous/gravity ratio, recovery process (secondary, tertiary, or water-alternating-gas (WAG)), and geological heterogeneity. For large amplitude heterogeneities with short correlation lengths, the accuracy of the empirical models is shown to be less satisfactory, but improved by the addition of a diffusive term.

Fayers, F.J.; Blunt, M.J.; Christie, M.A. (BP Research Center (GB))

1992-05-01T23:59:59.000Z

233

Hydrogen storage materials and method of making by dry homogenation  

DOE Patents [OSTI]

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.

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

2002-01-01T23:59:59.000Z

234

Molecular Dynamics Simulation of Homogeneous Crystal Nucleation in Polyethylene  

E-Print Network [OSTI]

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 ...

Yi, Peng

235

Fuel effects in homogeneous charge compression ignition (HCCI) engines  

E-Print Network [OSTI]

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 ...

Angelos, John P. (John Phillip)

2009-01-01T23:59:59.000Z

236

Continuum Electrodynamics of a Piecewise-Homogeneous Linear Medium  

E-Print Network [OSTI]

The energy--momentum tensor and the tensor continuity equation serve as the conservation laws of energy, linear momentum, and angular momentum for a continuous flow. Previously, we derived equations of motion for macroscopic electromagnetic fields in a homogeneous linear dielectric medium that is draped with a gradient-index antireflection coating (J. Math Phys. 55, 042901 (2014) ). These results are consistent with the electromagnetic tensor continuity equation in the limit that reflections and the accompanying surface forces are negligible thereby satisfying the condition of an unimpeded flow in a thermodynamically closed system. Here, we take the next step and derive equations of motion for the macroscopic fields in the limiting case of a piecewise-homogeneous simple linear dielectric medium. The presence of radiation surface forces on the interface between two different homogeneous linear materials means that the energy--momentum formalism must be modified to treat separate homogeneous media in which the ...

Crenshaw, Michael E

2015-01-01T23:59:59.000Z

237

One-Directional Perfect Cloak Created With Homogeneous Material  

E-Print Network [OSTI]

A one-directional invisibility cloak is presented in this letter. Perfect invisibility can be achieved for TM waves along certain directions. The parameters are just homogeneously anisotropic and relatively easy for practical ...

Xi, Sheng

238

Dynamics of empty homogeneous isotropic three-dimensional spaces  

E-Print Network [OSTI]

It is shown that there are seven types of solutions described in the framework of general relativity theory (GRT), the dynamics of empty homogeneous isotropic three-dimensional spaces. Solution of the equations of GRT, which describes the dynamics of a homogeneous isotropic universe, in the limiting case of vanishingly small effect of matter on the metric properties of space must go to one of them.

A. V. Klimenko; V. A. Klimenko

2012-02-28T23:59:59.000Z

239

Heterogeneous ice nucleation and water uptake by field-collected...  

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

properties through heterogeneous nucleation is not well understood. Heterogeneous ice nucleation and water uptake by ambient particles collected from urban environments in...

240

HYPERSONIC BUCKSHOT: ASTROPHYSICAL JETS AS HETEROGENEOUS COLLIMATED PLASMOIDS  

SciTech Connect (OSTI)

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.

Yirak, Kristopher; Frank, Adam; Cunningham, Andrew J. [Department of Physics and Astronomy, University of Rochester, Rochester, NY 14620 (United States); Mitran, Sorin [Department of Mathematics, Applied Mathematics Program, University of North Carolina, Chapel Hill, NC 27599 (United States)], E-mail: yirak@pas.rochester.edu

2009-04-20T23:59:59.000Z

Note: This page contains sample records for the topic "homogeneous catalysis heterogeneous" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


241

Hypersonic Buckshot: Astrophysical Jets as Heterogeneous Collimated Plasmoids  

E-Print Network [OSTI]

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 ($r\\rho_{jet}$) 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.

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

2008-05-30T23:59:59.000Z

242

An Empirical Model for Heterogeneous Translucent Objects  

E-Print Network [OSTI]

scatter- ing in heterogeneous translucent objects. Motivated by the exponential fall-off of scattered in the marble example (Figure 3). Figure 3: The marble example. Left: Modulation texture and diffusely lit

Durand, Frédo

243

Dynamical Heterogeneities in Grains and Foams  

E-Print Network [OSTI]

Dynamical heterogeneities have been introduced in the context of the glass transition of molecular liquids and the lengthscale associated with them has been argued to be at the origin of the observed quasi-universal behaviour of glassy systems. Dense amorphous packings of granular media and foams also exhibit slow dynamics, intermittency and heterogeneities. We review a number of recent experimental studies of these systems, where one has direct access to the relevant space-time dynamics, allowing for direct visualisations of the dynamical heterogeneities. On one hand these visualisations provide a unique opportunity to access the microscopic mechanisms responsible for the growth of dynamical correlations. On the other hand focussing on the differences in these heterogeneities in microscopically different systems allows to discuss the range of the analogies between molecular thermal glasses and athermal glasses such as granular media and foams. Finally this review is the opportunity to discuss various approaches to actually extract quantitatively the dynamical lengthscale from experimental data.

Olivier Dauchot; Douglas J. Durian; Martin van Hecke

2010-10-05T23:59:59.000Z

244

Heterogeneous Recycling in Fast Reactors  

SciTech Connect (OSTI)

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.

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

2012-07-30T23:59:59.000Z

245

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

E-Print Network [OSTI]

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

2010-01-01T23:59:59.000Z

246

Kinetic simulation of heterogeneous catalytic processes: Ethane hydrogenolysis over supported group VIII metals  

SciTech Connect (OSTI)

A kinetic model for ethane hydrogenolysis over Pt, Pd, Ir, and Co was formulated in terms of essentially two chemical parameters: the strength of bonding between atomic hydrogen and the metal surface and the strength of carbon-metal bonding between hydrocarbon fragments and the surface. These two surface bond strengths were estimated by calorimetric measurements of the heats of H{sub 2} and CO adsorption, combined with bond order conservation calculations. The results of the kinetic simulations suggest that ethane hydrogenolysis over Pt, Pd, Ir and Co takes place through irreversible C-C rupture of C{sub 2}H{sub 4} and C{sub 2}H{sub 3} surface species. Hydrogenation of monocarbon CH{sub y} fragments is kinetically insignificant. Dissociative adsorption of hydrogen is an equilibrated process, while dissociative adsorption of ethane is slow and reversible. Finally, the role of kinetic modeling in the formulation, interpretation, and generalization of experimental research in heterogeneous catalysis is discussed.

Goddard, S.A.; Amiridis, M.D.; Rekoske, J.E.; Cardona-Martinez, N.; Dumesic, J.A. (Univ. of Wisconsin, Madison (USA))

1989-05-01T23:59:59.000Z

247

Energy-Aware Multiband Communications in Heterogeneous Networks  

E-Print Network [OSTI]

operational and capital expenditures (OPEX and CAPEX) and energy consumption of heterogeneous cellular

Gesbert, David

248

Classification of Message Spreading in a Heterogeneous Social Network  

E-Print Network [OSTI]

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.

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

2015-01-01T23:59:59.000Z

249

Variable valve timing in a homogenous charge compression ignition engine  

DOE Patents [OSTI]

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.

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

2004-08-03T23:59:59.000Z

250

On the Mechanical Interaction of Light With Homogeneous Liquids  

E-Print Network [OSTI]

We investigate one of the consequences of the three competing models describing the mechanical interaction of light with a dielectric medium. According to both the Abraham and Minkowski models the time-averaged force density is zero inside a homogeneous dielectric, whereas the induced-current Lorentz force model predicts a non-zero force density. We argue that the latter force, if exists, could drive a hydrodynamic flow inside a homogeneous fluid. Our numerical experiments show that such flows have distinct spatial patterns and may influence the dynamics of particles in a water-based single-beam optical trap.

de Reus, Michiel

2013-01-01T23:59:59.000Z

251

A generalized 2D pencil beam scaling algorithm for proton dose calculation in heterogeneous slab geometries  

SciTech Connect (OSTI)

Purpose: Pencil beam algorithms are commonly used for proton therapy dose calculations. Szymanowski and Oelfke ['Two-dimensional pencil beam scaling: An improved proton dose algorithm for heterogeneous media,' Phys. Med. Biol. 47, 3313-3330 (2002)] developed a two-dimensional (2D) scaling algorithm which accurately models the radial pencil beam width as a function of depth in heterogeneous slab geometries using a scaled expression for the radial kernel width in water as a function of depth and kinetic energy. However, an assumption made in the derivation of the technique limits its range of validity to cases where the input expression for the radial kernel width in water is derived from a local scattering power model. The goal of this work is to derive a generalized form of 2D pencil beam scaling that is independent of the scattering power model and appropriate for use with any expression for the radial kernel width in water as a function of depth. Methods: Using Fermi-Eyges transport theory, the authors derive an expression for the radial pencil beam width in heterogeneous slab geometries which is independent of the proton scattering power and related quantities. The authors then perform test calculations in homogeneous and heterogeneous slab phantoms using both the original 2D scaling model and the new model with expressions for the radial kernel width in water computed from both local and nonlocal scattering power models, as well as a nonlocal parameterization of Moliere scattering theory. In addition to kernel width calculations, dose calculations are also performed for a narrow Gaussian proton beam. Results: Pencil beam width calculations indicate that both 2D scaling formalisms perform well when the radial kernel width in water is derived from a local scattering power model. Computing the radial kernel width from a nonlocal scattering model results in the local 2D scaling formula under-predicting the pencil beam width by as much as 1.4 mm (21%) at the depth of the Bragg peak for a 220 MeV proton beam in homogeneous water. This translates into a 32% dose discrepancy for a 5 mm Gaussian proton beam. Similar trends were observed for calculations made in heterogeneous slab phantoms where it was also noted that errors tend to increase with greater beam penetration. The generalized 2D scaling model performs well in all situations, with a maximum dose error of 0.3% at the Bragg peak in a heterogeneous phantom containing 3 cm of hard bone. Conclusions: The authors have derived a generalized form of 2D pencil beam scaling which is independent of the proton scattering power model and robust to the functional form of the radial kernel width in water used for the calculations. Sample calculations made with this model show excellent agreement with expected values in both homogeneous water and heterogeneous phantoms.

Westerly, David C. [Department of Radiation Oncology, University of Colorado School of Medicine, Aurora, Colorado 80045 (United States); Mo Xiaohu; DeLuca, Paul M. Jr. [Department of Medical Physics, School of Medicine and Public Health, University of Wisconsin, Madison, Wisconsin 53705 (United States); Tome, Wolfgang A. [Department of Medical Physics, School of Medicine and Public Health, University of Wisconsin, Madison, Wisconsin 53705 and Institute of Onco-Physics, Albert Einstein College of Medicine and Division of Medical Physics, Department of Radiation Oncology, Montefiore Medical Center, Bronx, New York 10461 (United States); Mackie, Thomas R. [Department of Medical Physics, School of Medicine and Public Health, University of Wisconsin, Madison, Wisconsin 53705 and Department of Human Oncology, School of Medicine and Public Health, University of Wisconsin, Madison, Wisconsin 53792 (United States)

2013-06-15T23:59:59.000Z

252

Proton Mediated Chemistry and Catalysis in a Self-Assembled Supramolecular Host  

SciTech Connect (OSTI)

Synthetic supramolecular host assemblies can impart unique reactivity to encapsulated guest molecules. Synthetic host molecules have been developed to carry out complex reactions within their cavities, despite the fact that they lack the type of specifically tailored functional groups normally located in the analogous active sites of enzymes. Over the past decade, the Raymond group has developed a series of self-assembled supramolecules and the Bergman group has developed and studied a number of catalytic transformations. In this Account, we detail recent collaborative work between these two groups, focusing on chemical catalysis stemming from the encapsulation of protonated guests and expanding to acid catalysis in basic solution. We initially investigated the ability of a water-soluble, self-assembled supramolecular host molecule to encapsulate protonated guests in its hydrophobic core. Our study of encapsulated protonated amines revealed rich host-guest chemistry. We established that self-exchange (that is, in-out guest movement) rates of protonated amines were dependent on the steric bulk of the amine rather than its basicity. The host molecule has purely rotational tetrahedral (T) symmetry, so guests with geminal N-methyl groups (and their attendant mirror plane) were effectively desymmetrized; this allowed for the observation and quantification of the barriers for nitrogen inversion followed by bond rotation. Furthermore, small nitrogen heterocycles, such as N-alkylaziridines, N-alkylazetidines, and N-alkylpyrrolidines, were found to be encapsulated as proton-bound homodimers or homotrimers. We further investigated the thermodynamic stabilization of protonated amines, showing that encapsulation makes the amines more basic in the cavity. Encapsulation raises the effective basicity of protonated amines by up to 4.5 pK{sub a} units, a difference almost as large as that between the moderate and strong bases carbonate and hydroxide. The thermodynamic stabilization of protonated guests was translated into chemical catalysis by taking advantage of the potential for accelerating reactions that take place via positively charged transition states, which could be potentially stabilized by encapsulation. Orthoformates, generally stable in neutral or basic solution, were found to be suitable substrates for catalytic hydrolysis by the assembly. Orthoformates small enough to undergo encapsulation were readily hydrolyzed by the assembly in basic solution, with rate acceleration factors up to 3900 compared with those of the corresponding uncatalyzed reactions. Furthering the analogy to enzymes that obey Michaelis-Menten kinetics, we observed competitive inhibition with the inhibitor NPr{sub 4}{sup +}, thereby confirming that the interior cavity of the assembly was the active site for catalysis. Mechanistic studies revealed that the assembly is required for catalysis and that the rate-limiting step of the reaction involves proton transfer from hydronium to the encapsulated substrate. Encapsulation in the assembly changes the orthoformate hydrolysis from an A-1 mechanism (in which decomposition of the protonated substrate is the rate-limiting step) to an A-S{sub E}2 mechanism (in which proton transfer is the rate-limiting step). The study of hydrolysis in the assembly was next extended to acetals, which were also catalytically hydrolyzed by the assembly in basic solution. Acetal hydrolysis changed from the A-1 mechanism in solution to an A-2 mechanism inside the assembly, where attack of water on the protonated substrate is rate limiting. This work provides rare examples of assembly-catalyzed reactions that proceed with substantial rate accelerations despite the absence of functional groups in the cavity and with mechanisms fully elucidated by quantitative kinetic studies.

Pluth, Michael; Bergman, Robert; Raymond, Kenneth

2009-04-10T23:59:59.000Z

253

A CHARACTERIZATION OF HOMOGENEOUS SPACES WITH POSITIVE HYPERBOLIC RANK  

E-Print Network [OSTI]

A CHARACTERIZATION OF HOMOGENEOUS SPACES WITH POSITIVE HYPERBOLIC RANK CHRISTOPHER CONNELL Abstract to be a rank one symmetric space. In particular, we show rigidity if such a space has positive hyperbolic rank greater than equal to that of its "abelian direction." The notion of hyperbolic-rank extends the notion

Connell, Christopher

254

Homogeneous Charge Compression Ignition: Formulation Effect of a Diesel Fuel  

E-Print Network [OSTI]

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 Compression Ignition: Formulation Effect of a Diesel Fuel on the Initiation and the Combustion - Potential

Paris-Sud XI, Université de

255

Homogenized Maxwell's Equations; a Model for Varistor Ceramics  

E-Print Network [OSTI]

from [3] of the electric field as a function of the current density for Zinc Oxide, ZnHomogenized Maxwell's Equations; a Model for Varistor Ceramics Bj¨orn Birnir Niklas Wellander and lower bounds are obtained for the effective conductivity in the varistor. These two bounds

Birnir, Björn

256

Homogenized Maxwell's Equations; a Model for Varistor Ceramics  

E-Print Network [OSTI]

from [3] of the electric field as a function of the current density for Zinc Oxide, ZnHomogenized Maxwell's Equations; a Model for Varistor Ceramics BjË? orn Birnir Niklas Wellander and lower bounds are obtained for the effective conductivity in the varistor. These two bounds

Birnir, Björn

257

Hopf Bifurcation and Oscillations in Homogeneous Communication Networks  

E-Print Network [OSTI]

Hopf Bifurcation and Oscillations in Homogeneous Communication Networks Huibing Yin Paul Wang and Engineering, University of Illinois at Urbana-Champaign, 1206 W. Green Street, Urbana, IL 61801. yin3,paulwang: In this paper, we investigate stability and bifurcation arising in a communication network model with a large

Alpcan, Tansu

258

HOMOGENEOUS MODELS IN GENERAL RELATIVITY AND GAS DYNAMICS  

E-Print Network [OSTI]

HOMOGENEOUS MODELS IN GENERAL RELATIVITY AND GAS DYNAMICS O. I. BOGOYAVLENSKII AND S. P. NOVIKOV analytically) in general relativity and gas dynamics. The investigation of these models is carried out begins with a short survey of results on non-trivial models (that is, those that are not integrable

Novikov, Sergei Petrovich

259

MESOSCALE MODELLING OF WIND ENERGY OVER NON-HOMOGENEOUS TERRAIN  

E-Print Network [OSTI]

MESOSCALE MODELLING OF WIND ENERGY OVER NON-HOMOGENEOUS TERRAIN (ReviewArticle) Y. MAHRER.1. OBSERVATIONALAPPROACHES Evaluations of wind energy based on wind observations (usually surface winds) at well, the resolution of the wind energy pattern throughout an extended area by this methodology requires a large number

Pielke, Roger A.

260

Anisotropic Homogeneous Cosmologies in the Post-Newtonian Approximation  

E-Print Network [OSTI]

In this paper we explore how far the post-Newtonian theory goes in overcoming the difficulties associated with anisotropic homogeneous cosmologies in the Newtonian approximation. It will be shown that, unlike in the Newtonian case, the cosmological equations of the post-Newtonian approximation are much more in the spirit of general relativity with regard to the nine Bianchi types and issues of singularities. The situations of vanishing rotation and vanishing shear are treated separately. The homogeneous Bianchi I model is considered as an example of a rotation-free cosmology with anisotropy. It is found in the Newtonian approximation that there are arbitrary functions that need to be given for all time if the initial value problem is to be well-posed, while in the post-Newtonian case there is no such need. For the general case of a perfect fluid only the post-Newtonian theory can satisfactorily describe the effects of pressure. This is in accordance with findings in an earlier paper where the post-Newtonian approximation was applied to homogeneous cosmologies. For a shear-free anisotropic homogeneous cosmology the Newtonian theory of Heckmann and Sch\\"ucking is explored. Comparisons with its relativistic and post-Newtonian counterparts are made. In the Newtonian theory solutions exist to which there are no analogues in general relativity. The post-Newtonian approximation may provide a way out.

Tamath Rainsford

2000-07-23T23:59:59.000Z

Note: This page contains sample records for the topic "homogeneous catalysis heterogeneous" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


261

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

E-Print Network [OSTI]

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

MacMillan, David W. C.

262

Conformationally controlled pK-switching in membrane proteins: One more mechanism specic to the enzyme catalysis?  

E-Print Network [OSTI]

-active tyrosine YZ in the oxygen- evolving photosystem II. It is conceivable that YZ switches its pK from VV4 to general mechanisms of enzymatic catalysis. In the bacterial photosyn- thetic reaction center (RC transfer; Photosynthetic reaction center; Bacteriorhodopsin; Photosystem II 1. Introduction The nature

Steinhoff, Heinz-Jürgen

263

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

264

Effects of catalysis on particle motion in plane-parallel and cylindrical channels in a catalytic reactor  

SciTech Connect (OSTI)

A theoretical study is made on aerosol behavior in a catalysis zone for a plane-parallel or cylindrical channel in a catalytic reactor. It is found that the thermophoretic trapping coefficient may attain 10-15% in a laminar flow having longitudinal Pe and Re >> 1 even for small relative temperature differences.

Kabanov, A.N.; Murashkevich, F.I.; Shulimanova, Z.L.; Shukin, E.R.

1987-09-01T23:59:59.000Z

265

General basic and coordination catalysis in reactions of haloaromatic compounds with ammonia in the presence of copper(I) compounds  

SciTech Connect (OSTI)

This paper presents a study made to detect general basic catalysis by ammonia (reagent) in reactions of ammonolysis of haloaromatic compounds in the presence of Cu/sup +/ ions, as well as to determine the generality of the mechanisms of the catalytic replacement of a halogen atom by an amino group in the anthraquinone and benzene series.

Chumak, V.T.; Shein, S.M.

1985-11-01T23:59:59.000Z

266

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:1 First Use of Energy for All Purposes (Fuel and Nonfuel),Feet) Year Jan Feb Mar Apr MayAtmospheric Optical Depth7-1D: Vegetation Proposed New Substation Sites ProposedOccupational Health Services >

267

Design, Synthesis and Mechanistic Evaluation of Iron-Based Catalysis for Synthesis Gas Conversion to Fuels and Chemicals  

SciTech Connect (OSTI)

This project extends previously discovered Fe-based catalysts to hydrogen-poor synthesis gas streams derived from coal and biomass sources. These catalysts have shown unprecedented Fischer-Tropsch synthesis rates and selectivities for synthesis gas derived from methane. During the first reporting period, we certified a microreactor, installed required analytical equipment, and reproduced synthetic protocols and catalytic results previously reported. During the second reporting period, we prepared several Fe-based compositions for Fischer-Tropsch Synthesis and tested the effects of product recycle under both subcritical and supercritical conditions. During the third and fourth reporting periods, we improved the catalysts preparation method, which led to Fe-based materials with the highest FTS reaction rates and selectivities so far reported, a finding that allowed their operation at lower temperatures and pressures with high selectivity to desired products (C{sub 5+}, olefins). During the fifth and sixth reporting period, we studied the effects of different promoters on catalytic performance, specifically how their sequence of addition dramatically influenced the performance of these materials in the Fischer-Tropsch synthesis. We also continued our studies of the kinetic behavior of these materials during the sixth reporting period. Specifically, the effects of H{sub 2}, CO, and CO{sub 2} on the rates and selectivities of Fischer-Tropsch Synthesis reactions led us to propose a new sequence of elementary steps on Fe and Co Fischer-Tropsch catalysts. Finally, we also started a study of the use of colloidal precipitation methods for the synthesis small Co clusters using recently developed methods to explore possible further improvements in FTS rates and selectivities. We found that colloidal synthesis makes possible the preparation of small cobalt particles, although large amount of cobalt silicate species, which are difficult to reduce, were formed. During this seventh reporting period, we have explored several methods to modify the silanol groups on SiO{sub 2} by using either a homogeneous deposition-precipitation method or surface titration of Si-OH on SiO{sub 2} with zirconium (IV) ethoxide to prevent the formation of unreducible and unreactive CoO{sub x} species during synthesis and FTS catalysis. We have synthesized monometallic Co/ZrO{sub 2}/SiO{sub 2} catalysts with different Co loadings (11-20 wt%) by incipient wetness impregnation methods and characterized the prepared Co supported catalysts by H{sub 2} temperature-programmed reduction (H{sub 2}-TPR) and H{sub 2}-chemisorption. We have measured the catalytic performance in FTS reactions and shown that although the hydroxyl groups on the SiO{sub 2} surface are difficult to be fully titrated by ZrO{sub 2}, modification of ZrO{sub 2} on SiO{sub 2} surface can improve the Co clusters dispersion and lead to a larger number of exposed Co surface atoms after reduction and during FTS reactions. During this seventh reporting period, we have also advanced our development of the reaction mechanism proposed in the previous reporting period. Specifically, we have shown that our novel proposal for the pathways involved in CO activation on Fe and Co catalysts is consistent with state-of-the-art theoretical calculations carried out in collaboration with Prof. Manos Mavrikakis (University of Wisconsin-Madison). Finally, we have also worked on the preparation of several manuscripts describing our findings about the preparation, activation and mechanism of the FTS with Fe-based catalysts and we have started redacting the final report for this project.

Akio Ishikawa; Manuel Ojeda; Nan Yao; Enrique Iglesia

2007-03-31T23:59:59.000Z

268

Heterogeneous lithium niobate photonics on silicon substrates  

E-Print Network [OSTI]

Heterogeneous lithium niobate photonics on silicon substrates Payam Rabiei,1,* Jichi Ma,1 Saeed-confined lithium niobate photonic devices and circuits on silicon substrates is reported based on wafer bonding high- performance lithium niobate microring optical resonators and Mach- Zehnder optical modulators

Fathpour, Sasan

269

Modeling the Energy Efficiency of Heterogeneous Clusters  

E-Print Network [OSTI]

on heterogeneous clusters ­ Unexplored from energy-time performance perspective 10-Sep-14 ICPP 2014 7 #12;Objectiveth September 2014 43rd International Conference on Parallel Processing, Minneapolis, MN, USA #12;Outline · Motivation · Objective · Methodology · Analysis · Conclusions 10-Sep-14 2ICPP 2014 #12;Energy

Teo, Yong-Meng

270

Chimera states in heterogeneous Kuramoto networks  

E-Print Network [OSTI]

Chimera states in heterogeneous Kuramoto networks Carlo R. Laing IIMS, Massey University, Auckland discovered by Kuramoto c. 2002; named "chimeras" by Strogatz. #12;· Identical oscillators, so why coherent/incoherent groups? · This type of solution discovered by Kuramoto c. 2002; named "chimeras" by Strogatz. #12

Laing, Carlo R.

271

ON DIFFUSION IN HETEROGENEOUS MEDIA YOUXUE ZHANG*,  

E-Print Network [OSTI]

, heterogeneous media, multi-mineral rocks, multi-phase media, composite materials, kinetics, porous rocks to bulk diffusion, and porous materials (such as plants, soil, rock with partial melt or fluid, sediment of air and moisture in soils, drying of paint, wood, and concrete, diffusion of gases in rubber, movement

Liu, Liping

272

Transport Control Protocol (TCP) In Heterogeneous Networks  

E-Print Network [OSTI]

Sprint Transport Control Protocol (TCP) In Heterogeneous Networks Objectives · Principles of TCP functional modules: slow start, congestion avoidance, fast transmission and fast recovery. ­ Maintain · Packet dropping is the only indication signal for network congestion (Maybe?) · Different transmission

Shihada, Basem

273

Heterogeneous Temporal Probabilistic Agents JURGEN DIX  

E-Print Network [OSTI]

and software modules. We will define the concept of a heterogeneous temporal probabilistic (HTP) agent). Intuitively, an FTPSI specifies what all an HTP agent is permitted/forbidden/obliged to do at various times t. As changes occur in the environment, the HTP agent must compute a new FTPSI. HTP agents continuously compute

Kraus, Sarit

274

Phylogenetic Quantification of Intra-tumour Heterogeneity  

E-Print Network [OSTI]

, et al. (2014) Phylogenetic Quantification of Intra-tumour Heterogeneity. PLoS Comput Biol 10(4): e1003535. doi:10.1371/journal.pcbi.1003535 Editor: Niko Beerenwinkel, ETH Zurich, Switzerland Received July 17, 2013; Accepted February 5, 2014; Published...

Schwarz, Roland F.; Trinh, Anne; Sipos, Botond; Brenton, James D.; Goldman, Nick; Markowetz, Florian

2014-04-17T23:59:59.000Z

275

Characterization of oil and gas reservoir heterogeneity  

SciTech Connect (OSTI)

Research described In this report addresses the internal architecture of two specific reservoir types: restricted-platform carbonates and fluvial-deltaic sandstones. Together, these two reservoir types contain more than two-thirds of the unrecovered mobile oil remaining ill Texas. The approach followed in this study was to develop a strong understanding of the styles of heterogeneity of these reservoir types based on a detailed outcrop description and a translation of these findings into optimized recovery strategies in select subsurface analogs. Research targeted Grayburg Formation restricted-platform carbonate outcrops along the Algerita Escarpment and In Stone Canyon In southeastern New Mexico and Ferron deltaic sandstones in central Utah as analogs for the North Foster (Grayburg) and Lake Creek (Wilcox) units, respectively. In both settings, sequence-stratigraphic style profoundly influenced between-well architectural fabric and permeability structure. It is concluded that reservoirs of different depositional origins can therefore be categorized Into a heterogeneity matrix'' based on varying intensity of vertical and lateral heterogeneity. The utility of the matrix is that it allows prediction of the nature and location of remaining mobile oil. Highly stratified reservoirs such as the Grayburg, for example, will contain a large proportion of vertically bypassed oil; thus, an appropriate recovery strategy will be waterflood optimization and profile modification. Laterally heterogeneous reservoirs such as deltaic distributary systems would benefit from targeted infill drilling (possibly with horizontal wells) and improved areal sweep efficiency. Potential for advanced recovery of remaining mobile oil through heterogeneity-based advanced secondary recovery strategies In Texas is projected to be an Incremental 16 Bbbl. In the Lower 48 States this target may be as much as 45 Bbbl at low to moderate oil prices over the near- to mid-term.

Tyler, N.; Barton, M.D.; Bebout, D.G.; Fisher, R.S.; Grigsby, J.D.; Guevara, E.; Holtz, M.; Kerans, C.; Nance, H.S.; Levey, R.A.

1992-10-01T23:59:59.000Z

276

Asymmetry of rotational catalysis of single membrane-bound F0F1-ATP synthase  

E-Print Network [OSTI]

Synthesis of the cellular 'energy currency' ATP is catalyzed by membrane-bound F0F1-ATP synthases. The chemical reaction at three binding sites in the F1 part is coupled to proton translocation through the membrane-integrated F0 part by an internal rotation of subunits. We examined the rotary movements of the epsilon-subunit of the 'rotor' with respect to the b-subunits of the 'stator' by single-molecule fluorescence resonance energy transfer (FRET). Rotation of epsilon during ATP hydrolysis is divided into three major steps with constant FRET level corresponding to three binding sites. Different catalytic activities of the individual binding sites were observed depending on the relative orientation of the 'rotor'. Computer simulations of the FRET signals and non-equally distributed orientations of epsilon strongly corroborate asymmetry of catalysis in F0F1-ATP synthase.

Zarrabi, Nawid; Diez, Manuel; Graeber, Peter; Wrachtrup, Joerg; Boersch, Michael

2007-01-01T23:59:59.000Z

277

Protein conformational dynamics in the mechanism of HIV-1 protease catalysis  

SciTech Connect (OSTI)

We have used chemical protein synthesis and advanced physical methods to probe dynamics-function correlations for the HIV-1 protease, an enzyme that has received considerable attention as a target for the treatment of AIDS. Chemical synthesis was used to prepare a series of unique analogues of the HIV-1 protease in which the flexibility of the 'flap' structures (residues 37-61 in each monomer of the homodimeric protein molecule) was systematically varied. These analogue enzymes were further studied by X-ray crystallography, NMR relaxation, and pulse-EPR methods, in conjunction with molecular dynamics simulations. We show that conformational isomerization in the flaps is correlated with structural reorganization of residues in the active site, and that it is preorganization of the active site that is a rate-limiting factor in catalysis.

Torbeev, Vladimir Yu.; Raghuraman, H.; Hamelberg, Donald; Tonelli, Marco; Westler, William M.; Perozo, Eduardo; Kent, Stephen B.H. (GSU); (UW); (UC)

2013-09-17T23:59:59.000Z

278

Methane Oxidation to Methanol without CO2 Emission: Catalysis by Atomic Negative Ions  

E-Print Network [OSTI]

The catalytic activities of the atomic Y-, Ru-, At-, In-, Pd-, Ag-, Pt-, and Os- ions have been investigated theoretically using the atomic Au- ion as the benchmark for the selective partial oxidation of methane to methanol without CO2 emission. Dispersion-corrected density-functional theory has been used for the investigation. From the energy barrier calculations and the thermodynamics of the reactions, we conclude that the catalytic effect of the atomic Ag-, At-, Ru-, and Os- ions is higher than that of the atomic Au- ion catalysis of CH4 conversion to methanol. By controlling the temperature around 290K (Os-), 300K (Ag-), 310K (At-), 320K (Ru-) and 325K (Au-) methane can be completely oxidized to methanol without the emission of CO2. We conclude by recommending the investigation of the catalytic activities of combinations of the above negative ions for significant enhancement of the selective partial oxidation of methane to methanol.

Tesfamichael, Aron; Felfli, Zineb; Msezane, Alfred Z

2014-01-01T23:59:59.000Z

279

Effect of Subgrid Heterogeneity on Scaling Geochemical and Biogeochemical Reactions: A Case of U(VI) Desorption  

SciTech Connect (OSTI)

The effect of subgrid heterogeneity in sediment properties on the rate of uranyl[U(VI)] desorption was investigated using a sediment collected from the US Department of Energy Hanford site. The sediment was sieved into 7 grain size fractions that each exhibited different U(VI) desorption properties. Six columns were assembled using the sediment with its grain size fractions arranged in different spatial configurations to mimic subgrid heterogeneity in reactive transport properties. The apparent rate of U(VI) desorption varied significantly in the columns. Those columns with sediment structures leading to preferential transport had much lower rates of U(VI) desorption than those with relatively homogeneous transport. Modeling analysis indicated that the U(VI) desorption model and parameters characterized from well-mixed reactors significantly over-predicted the measured U(VI) desorption in the columns with preferential transport. A dual domain model, which operationally separates reactive transport properties into two subgrid domains improved the predictions significantly. A similar effect of subgrid heterogeneity, albeit at a less degree, was observed for denitrification, which also occurred in the columns. The results imply that subgrid heterogeneity is an important consideration in extrapolating reaction rates from the laboratory to field.

Liu, Chongxuan; Shang, Jianying; Shan, Huimei; Zachara, John M.

2014-02-04T23:59:59.000Z

280

Apparatus for unilateral generation of a homogeneous magnetic field  

DOE Patents [OSTI]

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.

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

1988-01-01T23:59:59.000Z

Note: This page contains sample records for the topic "homogeneous catalysis heterogeneous" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


281

Apparatus for unilateral generation of a homogeneous magnetic field  

DOE Patents [OSTI]

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.

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

1984-05-01T23:59:59.000Z

282

High load operation in a homogeneous charge compression ignition engine  

DOE Patents [OSTI]

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

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)

2008-12-23T23:59:59.000Z

283

Nanoscale Heterogeneity of Polyamide Membranes Formed by Interfacial Polymerization  

E-Print Network [OSTI]

Nanoscale Heterogeneity of Polyamide Membranes Formed by Interfacial Polymerization Abstract theoretical model of polyamide membrane formation via interfacial polymerization. #12;

Freger, Viatcheslav "Slava"

284

ORIGINAL RESEARCH PAPER Gridding heterogeneous bathymetric data sets with stacked  

E-Print Network [OSTI]

heterogeneous bathymetric data sets for the compilation of Digital bathymetric models (DBMs), poses specific of the most widely used gridding methods, our approach yields superior DBMs based on heterogeneous bathymetric gridding algorithm has been specifically designed to con- struct DBMs from heterogeneous bathymetric source

Jakobsson, Martin

285

Design of heterogeneous turbine blade Xiaoping Qian, Deba Dutta*  

E-Print Network [OSTI]

Design of heterogeneous turbine blade Xiaoping Qian, Deba Dutta* Department of Mechanical in turbine drivers push the material capabilities of turbine blades to the limit. The recent development of heterogeneous objects by layered manufacturing offers new potentials for the turbine blades. In heterogeneous

Qian, Xiaoping

286

WSN-inspired Sleep Protocols for Heterogeneous LTE Networks  

E-Print Network [OSTI]

architecture becomes heterogenous, in particular 4G networks where LTE micro eNodeBs are deployed to strengthen algorithm to dynamically switch off and on the micro eNodeBs of an LTE heterogeneous network followingWSN-inspired Sleep Protocols for Heterogeneous LTE Networks Iulia Tunaru CEA CEA-Leti, Minatec

Paris-Sud XI, Université de

287

IMPACTS OF SOURCE TERM HETEROGENEITIES ON WATER PATHWAY DOSE.  

SciTech Connect (OSTI)

Radioactive sealed sources are used extensively throughout the world in different field and various activities such as medicine, agriculture, industry, research, education military applications, as well as nuclear facilities. The International Basic Safety Standards for Protection against Ionizing Radiation and for the Safety of Radiation sources [1] defines a sealed source as ''radioactive material that is (a) permanently sealed in capsule or (b) closely bounded and in a solid form. The capsule or material of sealed source shall be strong enough to maintain remain leak free under the conditions of use and wear for which the source was designed, also under foreseeable mishaps''. When a radioactive sealed source is no longer needed, or becomes unfit for the intended application it is considered spent. A spent sealed source is not necessarily a waste because it can be used in other applications. If for any technical or economic reason (decay, obsolete equipment and technique, worn out equipment) no further use is foreseen, the spent sealed source is considered spent and becomes radioactive waste [2] [3]. In addition, a source may be taken out of service temporarily or indefinitely. In this case the source is out of used (''disused'') but not considered spent [4]. Sources that are not in active use and have not being declared as spent are considered as disused sealed sources [4]. Considering the potential radiation hazards associated with such waste it has to be managed and disposed of in a way that will ensure that the potential radiation hazards are adequately managed and controlled in compliance with the appropriate safety principles and criteria. It is recognized that there exists today experience and means for all steps in the management of disused sealed sources, except disposal of [2]. In many countries, disused sealed sources represent a part of the radioactive waste inventory being characterized generally with high specific activities and small physical sizes and for which a solution has to be found in term of long-term disposal. Together with their casing and packaging, they are one form of heterogeneous waste; many other forms of waste with heterogeneous properties exist. They may arise in very small quantities and with very specific characteristics in the case of small producers, or in larger streams with standard characteristics in others. This wide variety of waste induces three main different levels of waste heterogeneity: (1) hot spot (e.g. disused sealed sources); (2) large item inside a package (e.g. metal components); and (3) very large items to be disposed of directly in the disposal unit (e.g. irradiated pipes, vessels). Safety assessments generally assume a certain level of waste homogeneity in most of the existing or proposed disposal facilities. There is a need to evaluate the appropriateness of such an assumption and the influence on the results of safety assessment. This need is especially acute in the case of sealed sources. There are many cases where are storage conditions are poor, or there is improper management leading to a radiological accident, some with significant or detrimental impacts. Disposal in a near surface disposal facility has been used in the past for some disused sealed sources. This option is currently in use for others sealed sources, or is being studied for the rest of them. The regulatory framework differs greatly between countries. In some countries, large quantities of disused sealed sources have been disposed of without any restriction, in others their disposal is forbidden by law. In any case, evaluation of the acceptability of disposal of disused sealed sources in near surface disposal facility is of utmost importance.

SULLIVAN, T.; GUSKOV, A.; POSKAS, P.; RUPERTI, N.; HANUSIK, V.; ET AL.

2004-09-15T23:59:59.000Z

288

Chemical Sciences and Engineering Division  

E-Print Network [OSTI]

· Heterogeneous and Homogenous Catalysis · Fuel Cell and Electrocatalysis Electrochemical Energy Storage Anthony Burrell · Materials Research · Technology Develop- ment · Engineering Research · Electrochemical Analysis Frontier Research Centers M. Thackeray C. Marshall Approved: ____________________________2/24/14 Mark

Kemner, Ken

289

Kinetics of oxidation of an organic amine with a Cr(V) salen complex in homogeneous aqueous solution and on the surface of mesoporous silica  

SciTech Connect (OSTI)

A comparative study of catalytic activity under homogeneous and heterogeneous conditions was carried out using the (salen)Cr{sup III}-catalyzed oxidation of tetramethylbenzidine (TMB) with iodosobenzene as a model reaction. Amine-functionalized mesoporous silica nanoparticles (MSN) were synthesized in a co-condensation reaction and functionalized with salen via a covalent Si-C bond. A Cr(III) complex of this supported ligand, MSN-(salen)Cr{sup III}, was prepared and characterized. Data from powder XRD, BET isotherms and BJH pore size distribution all showed that MSN-(salen)Cr{sup III} still had the typical MSN high surface area, narrow pore size distribution, and ordered hexagonal pore structure, which were further confirmed by transmission electron microscopy (TEM) images. {sup 13}C and {sup 29}Si solid-state NMR data provided structural information about the catalyst and verified successful functionalization of the salen ligand and coordination to Cr(III). No unreacted salen or Cr(III) were observed. The loadings of salen and salen-Cr{sup III} complex were determined via TGA and EDX, respectively. Both measurements indicated that approximately 0.5 mmol/g of catalyst was loaded on the surface of MSN. The oxidation of TMB with iodosobenzene using MSN-(salen)Cr{sup III} as a heterogeneous catalyst exhibited both similarities and differences with the analogous homogeneous reaction using (salen)Cr{sup III}(H{sub 2}O){sup +} as a catalyst in aqueous acetonitrile. In the presence of 0.10 M HClO{sub 4}, the two catalytic reactions proceeded at similar rates and generated the doubly oxidized product TMB{sup 2+}. In the absence of acid, the radical cation TMB{sup +} was produced. The kinetics of the heterogeneous reaction in the absence of added acid responded to concentrations of all three reagents, i.e. (salen)Cr{sup III}, TMB, and PhIO.

Szajna-Fuller, Ewa; Huang, Yulin; Rapp, Jennifer L.; Chaka, Gezhegn; Lin, Victor S.Y.; Pruski, Marek; Bakac, Andreja

2009-03-09T23:59:59.000Z

290

Homogenized dynamic constitutive relation for Bloch-wave propagation in periodic composites: structure and symmetries  

E-Print Network [OSTI]

Homogenized dynamic constitutive relation for Bloch-wave propagation in periodic composites composites has been made only very recently. Here we discuss the explicit form of the effective dynamic properties of composites with tailored microstructure necessitates a systematic homogenization procedure

Nemat-Nasser, Sia

291

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

SciTech Connect (OSTI)

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.

Mark A. Barteau

2009-09-15T23:59:59.000Z

292

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

E-Print Network [OSTI]

against the degradation of stearic acid under UV-A light illumination (365 nm). All chemically grown Zn degradation of stearic acid by c-axis oriented ZnO nanowires G. Kenanakisa,b,c,d, , N. Katsarakisa heterogeneous photocatalysis, which implies the use of an inert catalyst, non-hazardous oxidants and UV and

293

Controlling And Operating Homogeneous Charge Compression Ignition (Hcci) Engines  

DOE Patents [OSTI]

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.

Flowers, Daniel L. (San Leandro, CA)

2005-08-02T23:59:59.000Z

294

Homogeneous Charge Compression Ignition Free Piston Linear Alternator  

SciTech Connect (OSTI)

An experimental and theoretical investigation of a homogeneous charge compression ignition (HCCI) free piston powered linear alternator has been conducted to determine if improvements can be made in the thermal and conversion efficiencies of modern electrical generator systems. Performance of a free piston engine was investigated using a rapid compression expansion machine and a full cycle thermodynamic model. Linear alternator performance was investigated with a computer model. In addition linear alternator testing and permanent magnet characterization hardware were developed. The development of the two-stroke cycle scavenging process has begun.

Janson Wu; Nicholas Paradiso; Peter Van Blarigan; Scott Goldsborough

1998-11-01T23:59:59.000Z

295

Exhaust gas recirculation in a homogeneous charge compression ignition engine  

DOE Patents [OSTI]

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.

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)

2008-05-27T23:59:59.000Z

296

Lack of energy equipartition in homogeneous heated binary granular mixtures  

E-Print Network [OSTI]

We consider the problem of determining the granular temperatures of the components of a homogeneous binary heated mixture of inelastic hard spheres, in the framework of Enskog kinetic theory. Equations are derived for the temperatures of each species and their ratio, which is different from unity, as may be expected since the system is out of equilibrium. We focus on the particular heating mechanism where the inelastic energy loss is compensated by an injection through a random external force (``stochastic thermostat''). The influence of various parameters and their possible experimental relevance is discussed.

A. Barrat; E. Trizac

2002-05-21T23:59:59.000Z

297

A study of non-homogeneous absorbing Markov chains  

E-Print Network [OSTI]

the properties of p as related to the product of matrices. Lemma 1. Suppose A , A , . . . , A is a sequence of matrices with n-1 V(A ) & 0 for all k. Then, A . . . A A & 0. n ? 1 '' 2 1 Proof. Let A & 0 be a matrix such that p(A) & 0. For any column n... result k concerning the existence of lim A , where A is the transition matrix k~ of the Narkov chain. This result is generalized into a non-homogeneous Markov chain setting by allowing the transition matrix A to change at each step of time. This leads...

Bean, John Kevin

1975-01-01T23:59:59.000Z

298

Simulation of CO2 Sequestration at Rock Spring Uplift, Wyoming: Heterogeneity and Uncertainties in Storage Capacity, Injectivity and Leakage  

SciTech Connect (OSTI)

Many geological, geochemical, geomechanical and hydrogeological factors control CO{sub 2} storage in subsurface. Among them heterogeneity in saline aquifer can seriously influence design of injection wells, CO{sub 2} injection rate, CO{sub 2} plume migration, storage capacity, and potential leakage and risk assessment. This study applies indicator geostatistics, transition probability and Markov chain model at the Rock Springs Uplift, Wyoming generating facies-based heterogeneous fields for porosity and permeability in target saline aquifer (Pennsylvanian Weber sandstone) and surrounding rocks (Phosphoria, Madison and cap-rock Chugwater). A multiphase flow simulator FEHM is then used to model injection of CO{sub 2} into the target saline aquifer involving field-scale heterogeneity. The results reveal that (1) CO{sub 2} injection rates in different injection wells significantly change with local permeability distributions; (2) brine production rates in different pumping wells are also significantly impacted by the spatial heterogeneity in permeability; (3) liquid pressure evolution during and after CO{sub 2} injection in saline aquifer varies greatly for different realizations of random permeability fields, and this has potential important effects on hydraulic fracturing of the reservoir rock, reactivation of pre-existing faults and the integrity of the cap-rock; (4) CO{sub 2} storage capacity estimate for Rock Springs Uplift is 6614 {+-} 256 Mt at 95% confidence interval, which is about 36% of previous estimate based on homogeneous and isotropic storage formation; (5) density profiles show that the density of injected CO{sub 2} below 3 km is close to that of the ambient brine with given geothermal gradient and brine concentration, which indicates CO{sub 2} plume can sink to the deep before reaching thermal equilibrium with brine. Finally, we present uncertainty analysis of CO{sub 2} leakage into overlying formations due to heterogeneity in both the target saline aquifer and surrounding formations. This uncertainty in leakage will be used to feed into risk assessment modeling.

Deng, Hailin [Los Alamos National Laboratory; Dai, Zhenxue [Los Alamos National Laboratory; Jiao, Zunsheng [Wyoming State Geological Survey; Stauffer, Philip H. [Los Alamos National Laboratory; Surdam, Ronald C. [Wyoming State Geological Survey

2011-01-01T23:59:59.000Z

299

Mesoporous Silica Nanomaterials for Applications in Catalysis, Sensing, Drug Delivery and Gene Transfection  

SciTech Connect (OSTI)

The central theme of this dissertation is represented by the versatility of mesoporous silica nanomaterials in various applications such as catalysis and bio-applications, with main focus on biological applications of Mesoporous Silica Nanospheres (MSN). The metamorphosis that we impose to these materials from catalysis to sensing and to drug and gene delivery is detailed in this dissertation. First, we developed a synthetic method that can fine tune the amount of chemically accessible organic functional groups on the pores surface of MSN by exploiting electrostatic and size matching between the cationic alkylammonium head group of the cetyltrimethylammonium bromide (CTAB) surfactant and various anionic organoalkoxysilane precursors at the micelle-water interface in a base-catalyzed condensation reaction of silicate. Aiming nature imitation, we demonstrated the catalytic abilities of the MSNs, We utilized an ethylenediamine functional group for chelating Cu{sup 2+} as a catalytic functional group anchored inside the mesopores. Thus, a polyalkynylene-based conducting polymer (molecular wire) was synthesized within the Cu-functionalized MSNs silica catalyst. For sensing applications, we have synthesized a poly(lactic acid) coated mesoporous silica nanosphere (PLA-MSN) material that serves as a fluorescence sensor system for detection of amino-containing neurotransmitters in neutral aqueous buffer. We exploited the mesoporosity of MSNs for encapsulating pharmaceutical drugs. We examined bio-friendly capping molecules such as polyamidoamine dendrimers of generations G2 to G4, to prevent the drug leaching. Next, the drug delivery system employed MSNs loaded with Doxorubicin, an anticancer drug. The results demonstrated that these nano-Trojan horses have ability to deliver Doxorubicin to cancer cells and induce their death. Finally, to demonstrate the potential of MSN as an universal cellular transmembrane nanovehicle, we anchored positively charged dendrimers on the surface of MSN and utilize them to complex cationic DNA. The p-EGFP-CI gene-coated MSN nanocomposite was able to transfect cancer cell lines, such as human HeLa and CHO cancer cell lines. The gene carrier ability of MSNs was further proved by transfecting primary cells and cotransfecting of two different genes in cancer cell lines. In sum, MSN are versatile partners in several types of applications.

Daniela Rodica Radu

2005-12-19T23:59:59.000Z

300

Chemical Homogeneity in Collinder 261 and Implications for Chemical Tagging  

E-Print Network [OSTI]

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.

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

2006-11-28T23:59:59.000Z

Note: This page contains sample records for the topic "homogeneous catalysis heterogeneous" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


301

The moduli space of local homogeneous 3-geometries  

E-Print Network [OSTI]

For a canonical formulation of quantum gravity, the superspace of all possible 3-geometries on a Cauchy hypersurface of a 3+1-dimensional Lorentzian manifold plays a key role. While in the analogous 2+1-dimensional case the superspace of all Riemannian 2-geometries is well known, the structure of the superspace of all Riemannian 3-geometries has not yet been resolved at present. In this paper, an important subspace of the latter is disentangled: The superspace of local homogenous Riemannian 3-geometries. It is finite dimensional and can be factored by conformal scale dilations, with the flat space as the center of projection. The corresponding moduli space can be represented by homothetically normalized 3-geometries. By construction, this moduli space of the local homogenous 3-geometries is an algebraic variety. An explicit parametrization is given by characteristic scalar invariants of the Riemannian 3-geometry. Although the moduli space is not locally Euclidean, it is a Hausdorff space. Nevertheless, its topology is compatible with the non-Hausdorffian topology of the space of all Bianchi-Lie algebras, which characterize the moduli modulo differences in their anisotropy.

M. Rainer

1996-07-26T23:59:59.000Z

302

2 Accessibility of pores in coal to methane and carbon dioxide 3 Yuri B. Melnichenko a,b,  

E-Print Network [OSTI]

, membrane separation, and heterogeneous catalysis. The size, distribution and interconnectivity 34of pores

303

Argonne integrated heterogeneous file transfer network  

SciTech Connect (OSTI)

This presentation describes the computing environment at Argonne National Laboratory and the actions underway to implement a coherent hierarchy of computing systems connected through a heterogeneous file transfer network. A major goal of the Computing Services Division is to integrate heterogeneous computing elements incrementally into a nework, with the goal of having everything somehow connected to everything else. Using standard IBM networking protocols, we have already built a full-function computer-to-computer file transfer network of IBM and DEC VAX systems. Currently, the users on the IBM MVS and VM/CMS systems can use standard IBM commands to send files and mail to DEC VAX users and output devices, and they can receive files from the DEC VAX's as if they had been sent from other IBM systems; similarly, the DEC VAX users can use standard DEC commands to send files and mail to IBM users and output devices, and they can receive files from the IBM systems as if they had been sent from other DEC VAX systems. In fact, the VAXes can exchange files and mail among themselves via the IBM NJE-based network without the need for DECnet links between the VAXes. Because this integrated heterogeneous file transfer network uses the standard IBM peer-to-peer communications protocol, all of the Laboratory's IBM and DEC computers easily communicate with the approximately 170 other computers in the Bitnet university network. Plans call for further integration of existing HP 3000 systems and future word processing systems such as Exxon, NBI, or Wang; we believe it is vitally important to provide smooth paths into this network for users of personal desktop computers. 17 references.

Schofield, J.

1984-01-01T23:59:59.000Z

304

Heterogeneously integrated microsystem-on-a-chip  

DOE Patents [OSTI]

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.

Chanchani, Rajen (Albuquerque, NM)

2008-02-26T23:59:59.000Z

305

Catalysis and clean environment: What do these two have in common?  

SciTech Connect (OSTI)

The theme of the 1990s, ``Continual Expansion through Sustainable Development,`` is the outcome of interdisciplinary studies undertaken in the preceding two decades to arrest ongoing global environmental deterioration. A critical component of various international efforts to formulate and implement environmentally-sound technologies is the planned involvement of developing countries and countries with economies in-transition which are poised for explosive growth well into the twenty-first century but do not have policies or financial resources to simultaneously manage their environment. Though CO{sub 2}-producing, technologies utilizing relatively abundant and inexpensive carbon-based feedstocks will still play a major role on the scene. Related to this, the aim of the ongoing effort at Brookhaven National Laboratory is to develop technologies for enhancing natural gas and coal usage through liquid phase catalysis. A successful application of this concept in the synthesis of oxygenates is described. The potential impact of this activity on methanol-energy, non-petroleum feedstocks development, H{sub 2}-energy, CO{sub 2}-recycle, and several other areas in relation to CO{sub 2}-mitigation, is also discussed.

Mahajan, D.; Gupta, N.; Kobayashi, A.

1993-07-01T23:59:59.000Z

306

DFT calculations of EPR parameters of transition metal complexes: Implications for catalysis  

SciTech Connect (OSTI)

Transition metal and ligand hyperfine coupling constants for paramagnetic vanadium and copper model complexes have been calculated using DFT methods that are available in commercial software packages. Variations in EPR parameters with ligand identity and ligand orientation are two of the trends that have been investigated with DFT calculations. For example, the systematic variation of the vanadium hyperfine coupling constant with orientation for an imidazole ligand in a VO2+ complex has been observed experimentally and has also been reproduced by DFT calculations. Similarly, changes in the vanadium hyperfine coupling constant with ligand binding have been calculated using model complexes and DFT methods. DFT methods were also used to calculate ligand hyperfine coupling constants in transition metal systems. The variation of the proton hyperfine coupling constant with water ligand orientation was investigated for [VO(H2O)5]2+ and the results were used to interpret high resolution EPR data of VO2+-exchanged zeolites. Nitrogen hyperfine and quadrupole coupling constants for VO2+ model complexes were calculated and compared with experimental data. The computational results were used to enhance the interpretation of the EPR data for vanadium-exchanged zeolites which are promising catalytic materials. The implications of the DFT calculations of EPR parameters with respect to catalysis will be discussed

Saladino, Alexander C.; Larsen, Sarah C.

2005-07-15T23:59:59.000Z

307

Steam catalysis in CaO carbonation under low steam partial pressure  

SciTech Connect (OSTI)

CaO was widely used to capture CO{sub 2} in direct hydrogen production process, where steam always existed simultaneously. The effect of steam on CaO carbonation performance under low steam partial pressure was investigated using a pressurized thermogravimetric apparatus. The experimental results revealed that steam improved CaO carbonation performance significantly no matter whether Ca(OH){sub 2} was produced or not. At 823 K and 0.5 MPa of steam partial pressure, effect of steam on CaO carbonation performance could not be attributed mainly to production of Ca(OH){sub 2} because the hydration rate of CaO was very slow. The main reason was steam catalysis in CaO carbonation. Enhancement of steam on CaO carbonation performance without Ca(OH){sub 2} production could not be attributed to improvement of steam on the physical property, but to catalytic effect of steam. Effects of CaO precursors, CO{sub 2} partial pressure, steam partial pressure, and temperature with steam addition on CaO carbonation performance were also investigated.

Yang, S.J.; Xiao, Y.H. [Chinese Academy of Science, Beijing (China)

2008-06-15T23:59:59.000Z

308

Generalized quantum gravity condensates for homogeneous geometries and cosmology  

E-Print Network [OSTI]

We construct a generalized class of quantum gravity condensate states, that allows the description of continuum homogeneous quantum geometries within the full theory. They are based on similar ideas already applied to extract effective cosmological dynamics from the group field theory formalism, and thus also from loop quantum gravity. However, they represent an improvement over the simplest condensates used in the literature, in that they are defined by an infinite superposition of graph-based states encoding in a precise way the topology of the spatial manifold. The construction is based on the definition of refinement operators on spin network states, written in a second quantized language. The construction lends itself easily to be applied also to the case of spherically symmetric quantum geometries.

Daniele Oriti; Daniele Pranzetti; James P. Ryan; Lorenzo Sindoni

2015-01-05T23:59:59.000Z

309

Renewal convergence rates and correlation decay for homogeneous pinning models  

E-Print Network [OSTI]

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.

Giambattista Giacomin

2007-06-03T23:59:59.000Z

310

Statistical mechanics of homogeneous partly pinned fluid systems  

E-Print Network [OSTI]

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.

Vincent Krakoviack

2010-12-05T23:59:59.000Z

311

Testing gaussianity, homogeneity and isotropy with the cosmic microwave background  

E-Print Network [OSTI]

We review the basic hypotheses which motivate the statistical framework used to analyze the cosmic microwave background, and how that framework can be enlarged as we relax those hypotheses. In particular, we try to separate as much as possible the questions of gaussianity, homogeneity and isotropy from each other. We focus both on isotropic estimators of non-gaussianity as well as statistically anisotropic estimators of gaussianity, giving particular emphasis on their signatures and the enhanced "cosmic variances" that become increasingly important as our putative Universe becomes less symmetric. After reviewing the formalism behind some simple model-independent tests, we discuss how these tests can be applied to CMB data when searching for large scale "anomalies"

L. Raul Abramo; Thiago S. Pereira

2010-05-13T23:59:59.000Z

312

aquifer heterogeneity final: Topics by E-print Network  

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

Sciences Websites Summary: Sequential Consistency for Heterogeneous-Race-Free DEREK R. HOWER, BRADFORD M. BECKMANN, BENEDICT R: Sequential Consistency for Data-Race-Free (SC for...

313

aquifer property heterogeneity: Topics by E-print Network  

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

Sciences Websites Summary: Sequential Consistency for Heterogeneous-Race-Free DEREK R. HOWER, BRADFORD M. BECKMANN, BENEDICT R: Sequential Consistency for Data-Race-Free (SC for...

314

Heterogeneous Nucleation of Ice on Anthropogenic Organic Particles...  

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

Nucleation of Ice on Anthropogenic Organic Particles Collected in Mexico City. Heterogeneous Nucleation of Ice on Anthropogenic Organic Particles Collected in Mexico City....

315

A TEN MEGAWATT BOILING HETEROGENEOUS PACKAGE POWER REACTOR. Reactor...  

Office of Scientific and Technical Information (OSTI)

A TEN MEGAWATT BOILING HETEROGENEOUS PACKAGE POWER REACTOR. Reactor Design and Feasibility Problem Re-direct Destination: Temp Data Fields Rosen, M. A.; Coburn, D. B.; Flynn, T....

316

Heterogeneous Structure Around the Jemez Volcanic Field, New...  

Open Energy Info (EERE)

Data Abstract We analyse active-experiment seismic data obtained by the 1993 Jemez Tomography Experiment (JTEX) programme to elucidate the heterogeneous structure of the Jemez...

317

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

SciTech Connect (OSTI)

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.

White, J. M.; Bercaw, J.

2002-05-16T23:59:59.000Z

318

Dynamics on modular networks with heterogeneous correlations  

SciTech Connect (OSTI)

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.

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)

2014-06-15T23:59:59.000Z

319

Accelerating Subsurface Transport Simulation on Heterogeneous Clusters  

SciTech Connect (OSTI)

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.

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

2013-09-23T23:59:59.000Z

320

Numerical homogenization of concrete microstructures without explicit meshes  

SciTech Connect (OSTI)

Life management of electric hydro or nuclear power plants requires to estimate long-term concrete properties on facilities, for obvious safety and serviceability reasons. Decades-old structures are foreseen to be operational for several more decades. As a large number of different concrete formulations are found in EDF facilities, empirical models based on many experiments cannot be an option for a large fleet of power plant buildings. To build predictive models, homogenization techniques offer an appealing alternative. To properly upscale creep, especially at long term, a rather precise description of the microstructure is required. However, the complexity of the morphology of concrete poses several challenges. In particular, concrete is formulated to maximize the packing density of the granular skeleton, leading to aggregates spanning several length scales with small inter particle spacings. Thus, explicit meshing of realistic concrete microstructures is either out of reach of current meshing algorithms or would produce a number of degrees of freedom far higher than the current generic FEM codes capabilities. This paper proposes a method to deal with complex matrix-inclusions microstructures such as the ones encountered at the mortar or concrete scales, without explicitly meshing them. The microstructure is superimposed to an independent mesh, which is a regular Cartesian grid. This inevitably yields so called 'gray elements', spanning across multiple phases. As the reliability of the estimate of the effective properties highly depends on the behavior affected to these gray elements, special attention is paid to them. As far as the question of the solvers is concerned, generic FEM codes are found to lack efficiency: they cannot reach high enough levels of discretization with classical free meshes, and they do not take advantage of the regular structure of the mesh. Thus, a specific finite differences/finite volumes solver has been developed. At first, generic off-the-shelf linear system solvers were used. To further improve the efficiency in terms of memory requirements, specific variants of the preconditioned conjugate gradient were implemented. This allowed to homogenize the conductivity of a concrete-like microstructure using more than 10{sup 9} degrees of freedom on a rather common hardware for 2010 (a PC embedding 48 GB of RAM). Taking benefit of the properties of the regular Cartesian grid we have also investigated a multi-level method to improve the CPU efficiency of the code.

Sanahuja, Julien, E-mail: julien.sanahuja@edf.fr; Toulemonde, Charles, E-mail: charles.toulemonde@edf.fr

2011-12-15T23:59:59.000Z

Note: This page contains sample records for the topic "homogeneous catalysis heterogeneous" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


321

Structural, Spectroscopic, And Theoretical Elucidation of a Redox-Active Pincer-Type Ancillary Applied in Catalysis  

SciTech Connect (OSTI)

Pincer-type ligands are believed to be very robust scaffolds that can support multifarious functionalities as well as highly reactive metal motifs applied in organometallic chemistry, especially in the realm of catalysis. In this paper, we describe the redox and, therefore, noninnocent behavior of a PNP (PNP{sup -} = N[2-P(CHMe{sub 2}){sub 2}-4-methylphenyl]{sub 2}) pincer ancillary bound to nickel. A combination of structural, spectroscopic, and theoretical techniques suggests that this type of framework can house an electron hole when coordinated to Ni(II).

Adhikari, D.; Mossin, S.; Basuli, F.; Huffman, J.C.; Szilagyi, R.K.; Meyer, K.; Mindiola, D.J.

2009-05-11T23:59:59.000Z

322

The Specification and Execution of Heterogeneous Synchronous Reactive Systems  

E-Print Network [OSTI]

The Specification and Execution of Heterogeneous Synchronous Reactive Systems by Stephen Anthony in Engineering---Electrical Engineering and Computer Sciences in the GRADUATE DIVISION of the UNIVERSITY of Heterogeneous Synchronous Reactive Systems Copyright ã 1997 by Stephen Anthony Edwards #12; Abstract

323

The dynamics of chimera states in heterogeneous Kuramoto networks  

E-Print Network [OSTI]

The dynamics of chimera states in heterogeneous Kuramoto networks Carlo R. Laing a a. Abstract We study a variety of mixed synchronous/incoherent ("chimera") states in sev- eral heterogeneous with one another, while the remainder are incoherent [7­15], referred to by Abrams et al. as "chimera

Laing, Carlo R.

324

A Toolkit for Constraint Management in Heterogeneous Information Systems \\Lambda  

E-Print Network [OSTI]

to monitor and enforce distributed integrity constraints in loosely coupled heterogeneous information systems in such environments. Our framework is used to describe (1) interfaces provided by a database for the data items integrity constraints over data that is stored in a collec­ tion of loosely coupled heterogeneous

Chawathe, Sudarshan S.

325

Energy Conservation in Heterogeneous Server Clusters Taliver Heath  

E-Print Network [OSTI]

Energy Conservation in Heterogeneous Server Clusters #3; Taliver Heath Dept. of Computer Science, measurement Keywords Energy conservation, server clusters, heterogeneity #3; This research has been supported.g., [3, 4, 9, 21]) and dynamic cluster recon#12;guration for energy conservation without per- formance

Bianchini, Ricardo

326

SHORT COMMUNICATION Flow rate-modified streaming effects in heterogeneous  

E-Print Network [OSTI]

the streaming potential (Norde and Rouwendal 1990; Elgersma et al. 1992; Werner et al. 1999) or streamingSHORT COMMUNICATION Flow rate-modified streaming effects in heterogeneous microchannels Junjie Zhu relations is developed to study the streaming potential and streaming current in heterogeneous micro

Xuan, Xiangchun "Schwann"

327

On the Numerical Simulation of Waterflooding of Heterogeneous  

E-Print Network [OSTI]

On the Numerical Simulation of Waterflooding of Heterogeneous Petroleum Reservoirs Jim Douglas, Jr Simulation of Waterflooding of Heterogeneous Petroleum Reservoirs · A two-stage operator-splitting allows consider as a model problem the two-phase immiscible displacement in petroleum reservoirs. A very detailed

Furtado, Fred

328

On the Numerical Simulation of Waterflooding of Heterogeneous  

E-Print Network [OSTI]

On the Numerical Simulation of Waterflooding of Heterogeneous Petroleum Reservoirs Jim Douglas, Jr displacement in petroleum reservoirs. A very detailed description of the numerical method is presented. Follow, 22290 Rio de Janeiro, RJ, Brazil #12; On the Numerical Simulation of Waterflooding of Heterogeneous

Douglas Jr., Jim

329

Mining Competitive Relationships by Learning across Heterogeneous Networks  

E-Print Network [OSTI]

. Existing studies mainly focus on mining competitive relationships within a single data source, whileMining Competitive Relationships by Learning across Heterogeneous Networks Yang Yang , Jie Tang. In this paper, we study the problem of mining competitive rela- tionships by learning across heterogeneous

Menczer, Filippo

330

E-Print Network 3.0 - area homogeneous metallic Sample Search...  

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

Ecole Polytechnique, Centre de mathmatiques Collection: Mathematics 7 ISOTOPICALLY HEAVY AND HETEROGENEOUS C IN GRAPHITE OF THE VACA MUERTA MESOSIDERITE. T. Maruoka1 Summary:...

331

E-Print Network 3.0 - activity feed homogeneity Sample Search...  

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

results for: activity feed homogeneity Page: << < 1 2 3 4 5 > >> 1 Bistro Data Feed Management System Theodore Johnson Vladislav Shkapenyuk Divesh Srivastava Summary:...

332

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

E-Print Network [OSTI]

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

Sathrum, Aaron John

2011-01-01T23:59:59.000Z

333

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

E-Print Network [OSTI]

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 ...

Andreae, Morgan M. (Morgan MacKenzie)

2006-01-01T23:59:59.000Z

334

Method of fabricating a homogeneous wire of inter-metallic alloy  

DOE Patents [OSTI]

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.

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

2001-01-01T23:59:59.000Z

335

Soliton ratchets in homogeneous nonlinear Klein-Gordon systems  

E-Print Network [OSTI]

We study in detail the ratchet-like dynamics of topological solitons in homogeneous nonlinear Klein-Gordon systems driven by a bi-harmonic force. By using a collective coordinate approach with two degrees of freedom, namely the center of the soliton, $X(t)$, and its width, $l(t)$, we show, first, that energy is inhomogeneously pumped into the system, generating as result a directed motion; and, second, that the breaking of the time shift symmetry gives rise to a resonance mechanism that takes place whenever the width $l(t)$ oscillates with at least one frequency of the external ac force. In addition, we show that for the appearance of soliton ratchets, it is also necesary to break the time-reversal symmetry. We analyze in detail the effects of dissipation in the system, calculating the average velocity of the soliton as a function of the ac force and the damping. We find current reversal phenomena depending on the parameter choice and discuss the important role played by the phases of the ac force. Our analytical calculations are confirmed by numerical simulations of the full partial differential equations of the sine-Gordon and $\\phi^4$ systems, which are seen to exhibit the same qualitative behavior. Our results are in agreement with recent experimental work on dissipation induced symmetry breaking.

Luis Morales-Molina; Niurka R. Quintero; Franz G. Mertens; Angel Sanchez

2005-11-30T23:59:59.000Z

336

Condensation of cloud microdroplets in homogeneous isotropic turbulence  

E-Print Network [OSTI]

The growth by condensation of small water droplets in a three-dimensional homogeneous isotropic turbulent flow is considered. Within a simple model of advection and condensation, the dynamics and growth of millions of droplets are integrated. A droplet-size spectra broadening is obtained and it is shown to increase with the Reynolds number of turbulence, by means of two series of direct numerical simulations at increasing resolution. This is a key point towards a proper evaluation of the effects of turbulence for condensation in warm clouds, where the Reynolds numbers typically achieve huge values. The obtained droplet-size spectra broadening as a function of the Reynolds number is shown to be consistent with dimensional arguments. A generalization of this expectation to Reynolds numbers not accessible by DNS is proposed, yielding upper and lower bounds to the actual size-spectra broadening. A further DNS matching the large scales of the system suggests consistency of the picture drawn, while additional effort is needed to evaluate the impact of this effect for condensation in more realistic cloud conditions.

Alessandra S. Lanotte; Agnese Seminara; Federico Toschi

2008-07-15T23:59:59.000Z

337

Homogeneous ice nucleation evaluated for several water models  

E-Print Network [OSTI]

In this work, we evaluate by means of computer simulations the rate for ice homogeneous nucleation for several water models such as TIP4P, TIP4P/2005,TIP4P/ICE, and mW (following the same procedure as in Sanz et al. [J. Am. Chem. Soc.135, 15008 (2013)]) in a broad temperature range. We estimate the ice-liquid interfacial free-energy, and conclude that for all water models {\\gamma} decreases as the temperature decreases. Extrapolating our results to the melting temperature, we obtain a value of the interfacial free-energy between 25 and 32 mN/m in reasonable agreement with the reported experimental values. Moreover, we observe that the values of {\\gamma} depend on the chosen water model and this is a key factor when numerically evaluating nucleation rates, given that the kinetic prefactor is quite similar for all water models with the exception of the mW (due to the absence of hydrogens). Somewhat surprisingly the estimates of the nucleation rates found in this work for TIP4P/2005 are slightly higher than those of the mW model, even though the former has explicit hydrogens. Our results suggest that it may be possible to observe in computer simulations spontaneous crystallization of TIP4P/2005 at about 60 K below the melting point.

J. R. Espinosa; E. Sanz; C. Valeriani; C. Vega

2014-11-25T23:59:59.000Z

338

Geodesic Particle Paths Inside a Nonrotating, Homogeneous, Spherical Body  

E-Print Network [OSTI]

Proceeding from a solution of field equations that are improved versions of Einstein's nonvacuum gravitational field equations one is able to calculate precisely the trajectories of particles traveling inside a nonrotating, homogeneous, spherical body. Application of the results to the conditions of recent measurements of neutrino flight times between a source point A at CERN's European Laboratory for Particle Physics and a point B in either of two detectors (ICARUS or OPERA) at LNGS (Laboratori Nazionale del Gran Sasso), separated by a euclidean distance d(A,B) = 731 km, predicts for the flight time from A to B of a 2 eV neutrino launched with energy 17 GeV, as measured by a clock at B synchronized to a similar clock at A, approximately d/c + 9.3 x 10^{-16} sec. But as measured by inertial observers along the path the predicted flight time is approximately d/c - 2.6 x 10^{-9} sec and the predicted path length is approximately d - 8.4 x 10^{-7} m, which yields c + 321 m/sec for the predicted average inertially referenced speed of the neutrino from A to B.

Homer G. Ellis

2012-10-18T23:59:59.000Z

339

Dynamic control of a homogeneous charge compression ignition engine  

DOE Patents [OSTI]

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.

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)

2008-06-03T23:59:59.000Z

340

Modeling of homogeneous charge compression ignition (HCCI) of methane  

SciTech Connect (OSTI)

The operation of piston engines on a compression ignition cycle using a lean, homogeneous charge has many potential attractive features. These include the potential for extremely low NO{sub x} and particulate emissions while maintaining high thermal efficiency and not requiring the expensive high pressure injection system of the typical modem diesel engine. Using the HCT chemical kinetics code to simulate autoignition of methane-air mixtures, we have explored the ignition timing, burn duration, NO{sub x} production, indicated efficiency and power output of an engine with a compression ratio of 15:1 at 1200 and 2400 rpm. HCT was modified to include the effects of heat transfer. This study used a single control volume reaction zone that varies as a function of crank angle. The ignition process is controlled by varying the intake equivalence ratio and varying the residual gas trapping (RGT). RGT is internal exhaust gas recirculation which recycles both heat and combustion product species. It is accomplished by varying the timing of the exhaust valve closure. Inlet manifold temperature was held constant at 330 Kelvins. Results show that there is a narrow range of operational conditions that show promise of achieving the control necessary to vary power output while keeping indicated efficiency above 50% and NO{sub x} levels below 100 ppm.

Smith, J.R.; Aceves, S.M.; Westbrook, C.; Pitz, W.

1997-05-01T23:59:59.000Z

Note: This page contains sample records for the topic "homogeneous catalysis heterogeneous" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


341

Panaches horizontaux non-Boussinesq en milieu homog\\`ene  

E-Print Network [OSTI]

The environmental impact of pollutants and effluents discharged into the atmosphere or the oceans has led researchers to conduct studies related to this issue. Several works have been carried out in this context in order to reduce the effect on the local environment. These types of ejections in nature are modeled as jets in the presence of a density gradient. In this study we treated the problem of inclined round turbulent buoyant jets and plumes ejected in a homogeneous or stratified fluid, at rest or in motion. The prediction of the flow behavior, i.e. the evolution of its variables, is first treated theoretically from a model whose formalism is valid in both the Boussinesq case as well as in the non-Boussinesq general case. Solving the equations governing the plumes is performed numerically using a Runge-Kutta 4th order. To validate the model, laboratory experiments are performed with round jets of air and helium for a wide range of densities. The confrontation theory-experience aims here to fix the limits...

Daddi-Moussa-Ider, Abdallah; Mehaddi, Rabah; Vauquelin, Olivier; Candelier, Fabien

2014-01-01T23:59:59.000Z

342

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]

indices); and [X]=horizontal axis (natural logarithm of income per capita — proxied here by GDP per capita). Regions and countries as Appendix 4. Regional figures are median values. However, in three regions where one country dominates, their data... ) direction. Hence, regional dummies will be reported below only within the income per capita range of their members.22 FIGURE 6 ? [X]=horizontal axis. Regions and countries as Appendix 4 and Figure 5. 1=dummy for SAf; 2=dummy for LA; 3=base...

Palma, José Gabriel

2011-01-26T23:59:59.000Z

343

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

DOE Patents [OSTI]

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).

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

2014-04-08T23:59:59.000Z

344

Thermal Decomposition of Dichlorosilane Investigated by Pulsed Laser Powered Homogeneous Pyrolysis  

E-Print Network [OSTI]

of vacuum flash pyrolysis of SiH 2Cl2. Ban and Gilbert6 observed SiCl2 by mass spectrometry under sili- conThermal 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

Swihart, Mark T.

345

Mechanisms of Homogeneous Nucleation of Polymers of Sickle Cell Anemia Hemoglobin in Deoxy State  

E-Print Network [OSTI]

Mechanisms of Homogeneous Nucleation of Polymers of Sickle Cell Anemia Hemoglobin in Deoxy State, TX 77204-4004, USA The primary pathogenic event of sickle cell anemia is the polymerization reserved. Keywords: sickle cell anemia; hemoglobin S polymerization; fiber nucleation; homogeneous

Vekilov, Peter

346

Effect of high pressure homogenization on the physical properties of milk  

E-Print Network [OSTI]

Milk was homogenized at pressures ranging from 17.2 MPa to 100 MPa to determine the effect of homogenization pressure on the fat globule size distribution, viscosity, color, and temperature changes in milk. Milk containing 0, 1.5 and 3.0% milk fat...

Gonzalez De Cossio, Carlos

1994-01-01T23:59:59.000Z

347

The saddle-node of nearly homogeneous wave trains in reaction-diffusion systems  

E-Print Network [OSTI]

The saddle-node of nearly homogeneous wave trains in reaction-diffusion systems Jens D homogeneous oscillations created in the bifurcation, we investigate existence and stability of wave trains trains and determine their stability on the unbounded real line. We confirm that the accompanying wave

Scheel, Arnd

348

Design and operating characteristics of a transient kinetic analysis...  

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

catalysis reactor system employing in situ transmission Abstract: A novel apparatus for gas-phase heterogeneous catalysis kinetics is described. The apparatus enables fast...

349

The building blocks of dynamical heterogeneities in dense granular media  

E-Print Network [OSTI]

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.

R. Candelier; O. Dauchot; G. Biroli

2009-01-22T23:59:59.000Z

350

Development of K-Basin High-Strength Homogeneous Sludge Simulants and Correlations Between Unconfined Compressive Strength and Shear Strength  

SciTech Connect (OSTI)

K-Basin sludge will be stored in the Sludge Transport and Storage Containers (STSCs) at an interim storage location on Central Plateau before being treated and packaged for disposal. During the storage period, sludge in the STSCs may consolidate/agglomerate, potentially resulting in high-shear-strength material. The Sludge Treatment Project (STP) plans to use water jets to retrieve K-Basin sludge after the interim storage. STP has identified shear strength to be a key parameter that should be bounded to verify the operability and performance of sludge retrieval systems. Determining the range of sludge shear strength is important to gain high confidence that a water-jet retrieval system can mobilize stored K-Basin sludge from the STSCs. The shear strength measurements will provide a basis for bounding sludge properties for mobilization and erosion. Thus, it is also important to develop potential simulants to investigate these phenomena. Long-term sludge storage tests conducted by Pacific Northwest National Laboratory (PNNL) show that high-uranium-content K-Basin sludge can self-cement and form a strong sludge with a bulk shear strength of up to 65 kPa. Some of this sludge has 'paste' and 'chunks' with shear strengths of approximately 3-5 kPa and 380-770 kPa, respectively. High-uranium-content sludge samples subjected to hydrothermal testing (e.g., 185 C, 10 hours) have been observed to form agglomerates with a shear strength up to 170 kPa. These high values were estimated by measured unconfined compressive strength (UCS) obtained with a pocket penetrometer. Due to its ease of use, it is anticipated that a pocket penetrometer will be used to acquire additional shear strength data from archived K-Basin sludge samples stored at the PNNL Radiochemical Processing Laboratory (RPL) hot cells. It is uncertain whether the pocket penetrometer provides accurate shear strength measurements of the material. To assess the bounding material strength and potential for erosion, it is important to compare the measured shear strength to penetrometer measurements and to develop a correlation (or correlations) between UCS measured by a pocket penetrometer and direct shear strength measurements for various homogeneous and heterogeneous simulants. This study developed 11 homogeneous simulants, whose shear strengths vary from 4 to 170 kPa. With these simulants, we developed correlations between UCS measured by a Geotest E-280 pocket penetrometer and shear strength values measured by a Geonor H-60 hand-held vane tester and a more sophisticated bench-top unit, the Haake M5 rheometer. This was achieved with side-by-side measurements of the shear strength and UCS of the homogeneous simulants. The homogeneous simulants developed under this study consist of kaolin clay, plaster of Paris, and amorphous alumina CP-5 with water. The simulants also include modeling clay. The shear strength of most of these simulants is sensitive to various factors, including the simulant size, the intensity of mixing, and the curing time, even with given concentrations of simulant components. Table S.1 summarizes these 11 simulants and their shear strengths.

Onishi, Yasuo; Baer, Ellen BK; Chun, Jaehun; Yokuda, Satoru T.; Schmidt, Andrew J.; Sande, Susan; Buchmiller, William C.

2011-02-20T23:59:59.000Z

351

Development of general inflow performance relationships (IPR's) for slanted and horizontal wells producing heterogeneous solution-gas drive reservoirs  

SciTech Connect (OSTI)

Since 1968, the Vogel equation has been used extensively and successfully for analyzing the inflow performance relationship (IPR) of flowing vertical wells producing by solution-gas drive. Oil well productivity can be rapidly estimated by using the Vogel IPR curve and well outflow performance. With recent interests on horizontal well technology, several empirical IPRs for solution-gas drive horizontal and slanted wells have been developed under homogeneous reservoir conditions. This report presents the development of IPRs for horizontal and slanted wells by using a special vertical/horizontal/slanted well reservoir simulator under six different reservoir and well parameters: ratio of vertical to horizontal permeability, wellbore eccentricity, stratification, perforated length, formation thickness, and heterogeneous permeability. The pressure and gas saturation distributions around the wellbore are examined. The fundamental physical behavior of inflow performance for horizontal wells is described.

Cheng, A.M.

1992-04-01T23:59:59.000Z

352

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

SciTech Connect (OSTI)

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.

None

2011-01-31T23:59:59.000Z

353

An approach to composing web services with context heterogeneity  

E-Print Network [OSTI]

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 ...

Madnick, Stuart E.

354

PARTITIONED ANALYSIS FOR DIMENSIONALLY-HETEROGENEOUS HYDRAULIC NETWORKS*  

E-Print Network [OSTI]

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

Buscaglia, Gustavo C.

355

Effect of Subgrid Heterogeneity on Scaling Geochemical and Biogeochemi...  

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

A Case of U(VI) Desorption. Abstract: The effect of subgrid heterogeneity in sediment properties on the rate of uranylU(VI) desorption was investigated using a sediment...

356

Dynamic Heterogeneity-Aware Resource Provisioning in the Cloud  

E-Print Network [OSTI]

energy-efficient computing [2]. As a result, reducing energy consumption has become a primary concern and cooling. Dynamic capacity provisioning is a promising approach for reducing energy consumption heterogeneous machines with different capacities and energy consumption characteristics. Meanwhile

Boutaba, Raouf

357

Well Productivity Enhancement of High Temperature Heterogeneous Carbonate Reservoirs  

E-Print Network [OSTI]

Acidizing is one of the most popular techniques for well productivity enhancement during oil and gas production. However, the treatment method is not very effective when the wellbore penetrates through multiple layers of heterogeneous reservoirs...

Wang, Guanqun

2014-05-08T23:59:59.000Z

358

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

359

Quantitative tumor heterogeneity assessment on a nuclear population  

E-Print Network [OSTI]

Quantitative tumor heterogeneity assessment on a nuclear population basis Anne-Sofie Wessel score in this area was performed. 110 of the 226 TMA cores were scored by a pathologist. The automatic

360

Green Radio Communications in a Heterogeneous Wireless Medium  

E-Print Network [OSTI]

1 Green Radio Communications in a Heterogeneous Wireless Medium Muhammad Ismail and Weihua Zhuang wireless communication networks. Such energy efficient solutions are referred to as green communication efficient wireless communication networks, due to environmental, financial, and quality

Zhuang, Weihua

Note: This page contains sample records for the topic "homogeneous catalysis heterogeneous" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


361

Entrainment of heterogeneous glycolytic oscillations in single cells  

E-Print Network [OSTI]

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...

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

2015-01-01T23:59:59.000Z

362

Heterogeneous-race-free Memory Models Derek R. Hower  

E-Print Network [OSTI]

1 Heterogeneous-race-free Memory Models Derek R. Hower , Blake A. Hechtman§ , Bradford M. Beckmann Electrical and Computer Engineering University of Wisconsin-Madison Computer Sciences {derek.hower, brad

Wood, David A.

363

Discrete Feature Approach for Heterogeneous Reservoir Production Enhancement  

SciTech Connect (OSTI)

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.

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

2002-07-26T23:59:59.000Z

364

Structure, Thermodynamics and Kinetics of Chemically Heterogeneous Interfaces  

E-Print Network [OSTI]

), and a metal alloy interface (Cu-Pb). In both systems, interfacial prefreezing (crystal formation above the melting point of the fluid) was observed and this prefreezing was seen to promote heterogeneous nucleation, when the systems were cooled below...

Palafox Hernandez, Jesus Pablo

2011-08-31T23:59:59.000Z

365

SELECTIVE REDUCTION OF NOX IN OXYGEN RICH ENVIRONMENTS WITH PLASMA-ASSISTED CATALYSIS: CATALYST DEVELOPMENT AND MECHANISTIC STUDIES  

SciTech Connect (OSTI)

The control of NOx (NO and NO2) emissions from so-called ''lean-burn'' vehicle engines remains a challenge. In recent years, there have been a number of reports that show that a plasma device combined with a catalyst can reduce as high as 90% or more of NOx in simulated diesel and other ''lean-burn'' exhaust. In the case of propylene containing simulated diesel exhaust, the beneficial role of a plasma treatment is now thought to be due to oxidation of NO to NO2, and the formation of partially oxidized hydrocarbons that are more active for the catalytic reduction of NO2 than propylene. Thus, the overall system can be most usefully described as hydrocarbon selective catalytic reduction (SCR) enhanced by 'reforming' the exhaust with a non-thermal plasma (NTP) device. For plasma-enhanced catalysis, both zeolite- and alumina-based materials have shown high activity, albeit in somewhat different temperature ranges, when preceded by an NTP reactor. This paper will briefly describe our research efforts aimed at optimizing the catalyst materials for NTP-catalysis devices based, in part, on our continuing studies of the NTP- and catalytic-reaction mechanisms. Various alkali- and alkaline earth-cation-exchanged Y zeolites have been prepared, their material properties characterized, and they have been tested as catalytic materials for NOx reduction in laboratory NTP-catalysis reactors. Interestingly, NO2 formed in the plasma and not subsequently removed over these catalysts, will back-convert to NO, albeit to varying extents depending upon the nature of the cation. Besides this comparative reactivity, we will also discuss selected synthesis strategies for enhancing the performance of these zeolite-based catalyst materials. A particularly important result from our mechanistic studies is the observation that aldehydes, formed during the plasma treatment of simulated diesel exhaust, are the important species for the reduction of NOx to N2. Indeed, acetaldehyde has been found to be especially effective in the thermal reduction of both NO and NO2 over Ba- and Na-Y zeolite catalysts.

Peden, C; Barlow, S; Hoard, J; Kwak, J; *Balmer-Millar, M; *Panov, A; Schmieg, S; Szanyi, J; Tonkyn, R

2003-08-24T23:59:59.000Z

366

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

E-Print Network [OSTI]

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.

Luis Carlos Garcia del Molino; Khashayar Pakdaman; Jonathan Touboul

2014-10-26T23:59:59.000Z

367

Tunable Solvents for Homogeneous Catalyst Recycle Jie Lu, Michael J. Lazzaroni, Jason P. Hallett, Andreas S. Bommarius,  

E-Print Network [OSTI]

for product purification and catalyst reuse. One example demonstrated is the dimethyl ether (DME)-water system, such as phase- transfer catalysis and near-critical water.2-4 Here we develop mixed-solvent systems of water and environmental advantages. In a mixed organic-aqueous tunable solvent (OATS), reactions between water

368

Anomalous Scaling and Refined Similarity of an Active Scalar in a Model of Homogeneous Turbulent Convection  

E-Print Network [OSTI]

Anomalous scaling in the statistics of an active scalar in homogeneous turbulent convection is studied using a dynamical shell model. We extend refined similarity ideas for homogeneous and isotropic turbulence to homogeneous turbulent convection and attribute the origin of the anomalous scaling to variations of the entropy transfer rate. We verify the consequences and thus the validity of our hypothesis by showing that the conditional statistics of the active scalar and the velocity at fixed values of entropy transfer rate are not anomalous but have simple scaling with exponents given by dimensional considerations, and that the intermittency corrections are given by the scaling exponents of the moments of the entropy transfer rate.

Emily S. C. Ching; W. C. Cheng

2007-11-07T23:59:59.000Z

369

Effect of homogenization pressure and milk composition on some physical properties of yogurt  

E-Print Network [OSTI]

(Fig. 7). The increase in firmness due to increased MF concentration was not linear. The increase in firmness that was observed when the MF concentration of the yogurt was increased &om 2 to 4% was much greater than the increase in firmness when MF...) Figure 6. Effect of homogenization pressure (HP) and solids-not-fat (SNF) on the firmness of yogurt. 25 120 4% MF 110 100 90 2% MF 80 70 0% MF 60 3000 6000 9000 12000 15000 Homogenization pressure (psi) Figure 7. Effect of homogenization...

Lin, Chun-An

1995-01-01T23:59:59.000Z

370

Research of a boundary condition quantifiable correction method in the assembly homogenization  

SciTech Connect (OSTI)

The methods and codes currently used in assembly homogenization calculation mostly adopt the reflection boundary conditions. The influences of real boundary conditions on the assembly homogenized parameters were analyzed. They were summarized into four quantifiable effects, and then the mathematical expressions could be got by linearization hypothesis. Through the calculation of a test model, it had been found that the result was close to transport calculation result when considering four boundary quantifiable effects. This method would greatly improve the precision of a core design code which using the assembly homogenization methods, but without much increase of the computing time. (authors)

Peng, L. H.; Liu, Z. H.; Zhao, J. [Inst. of Nuclear and New Energy Technology, Tsinghua Univ., Beijing, 100084 (China); Li, W. H. [China Nuclear Power Technology Research Inst., Shenzhen, 518026 (China)

2012-07-01T23:59:59.000Z

371

Boron-nitrogen-hydrogen (BNH) compounds: recent developments in hydrogen storage, applications in hydrogenation and catalysis, and new syntheses  

SciTech Connect (OSTI)

The strong efforts devoted to the exploration of BNH compounds for hydrogen storage have led to impressive advances in the field of boron chemistry. This review summarizes progress in this field from three aspects. It starts with the most recent developments in using BNH compounds for hydrogen storage, covering NH3BH3, B3H8¯ containing compounds, and CBN compounds. The following section then highlights interesting applications of BNH compounds in hydrogenation and catalysis. The last part is focused on breakthroughs in the syntheses and discovery of new BNH organic analogues. The role of N?H?+•••H?-?B dihydrogen interactions in molecule packing, thermal hydrogen evolution, and syntheses is also discussed within the review. Part of this research is supported by the U.S. Department of Energy’s Basic Energy Sciences, Division of Chemical Sciences, Biosciences and Geosciences. Pacific Northwest National Laboratory is operated by Battelle.

Huang, Zhenguo; Autrey, Thomas

2012-11-15T23:59:59.000Z

372

Crystal Structure of 12-Lipoxygenase Catalytic-Domain-Inhibitor Complex Identifies a Substrate-Binding Channel for Catalysis  

SciTech Connect (OSTI)

Lipoxygenases are critical enzymes in the biosynthesis of families of bioactive lipids including compounds with important roles in the initiation and resolution of inflammation and in associated diseases such as diabetes, cardiovascular disease, and cancer. Crystals diffracting to high resolution (1.9 {angstrom}) were obtained for a complex between the catalytic domain of leukocyte 12-lipoxygenase and the isoform-specific inhibitor, 4-(2-oxapentadeca-4-yne)phenylpropanoic acid (OPP). In the three-dimensional structure of the complex, the inhibitor occupied a new U-shaped channel open at one end to the surface of the protein and extending past the redox-active iron site that is essential for catalysis. In models, the channel accommodated arachidonic acid, defining the binding site for the substrate of the catalyzed reaction. There was a void adjacent to the OPP binding site connecting to the surface of the enzyme and providing a plausible access channel for the other substrate, oxygen.

Xu, Shu; Mueser, Timothy C.; Marnett, Lawrence J.; Funk, Jr., Max O. (Toledo); (Vanderbilt)

2014-10-02T23:59:59.000Z

373

Metal carbonyl-hydrosilane reactions and hydrosilation catalysis. Final report for period May 1, 1995 - August 14, 1999  

SciTech Connect (OSTI)

Manganese carbonyl complexes serve as hydrosilation precatalysts for selectively transforming a carbonyl group into a doxy methylene or a fully reduced methylene group. Substrates of interest include (1) aldehydes, ketones, carboxylic acids, silyl esters, and esters, and (2) their organometallic acyl counterparts. Two types of manganese precatalysts have been reported: (a) alkyl and acyl complexes (L)(CO){sub 4}MnR [L = CO, PPh{sub 3}; R = COCH{sub 3}, COPh, CH{sub 3}] and (b) halides (CO){sub 5}MnX and [(CO){sub 4}MnX]{sub 2} (X = Br, I). The former promote hydrosilation and deoxygenation catalysis; the latter promote dehydrogenative silation of alcohols and carboxylic acids as well as hydrosilation and deoxygenation of some metallocarboxylic acid derivatives. In every case studied, these Mn precatalysts are far more reactive or selective than traditional Rh(l) precatalysts. The reaction chemistry of the above and other Mn alkyl complexes with hydrosilanes was studied in order to probe catalysis mechanism(s). Thus, Mn(CO){sub 5} methyl, benzyl, acetyl, and benzoyl (4 p-substituents) complexes reacted with hydrosilines by four different mechanisms, which were established. A noteworthy development was that the methyl and benzoyl complexes gave moderate yields of a new ({eta}{sup 2}-Si-H) silane adduct (CO){sub 4}Mn(SiMe{sub 2}Ph)(H-SiMe{sub 2}Ph), which is stable in the presence of excess silane. This silane adduct promotes all three catalytic reactions; its extraordinary activity and potential selectivity are under study.

Cutler, Alan R.

2001-04-14T23:59:59.000Z

374

NMR CHARACTERIZATIONS OF PROPERTIES OF HETEROGENEOUS MEDIA  

SciTech Connect (OSTI)

A critical and long-standing need within the petroleum industry is the specification of suitable petrophysical properties for mathematical simulation of fluid flow in petroleum reservoirs (i.e., reservoir characterization). The development of accurate reservoir characterizations is extremely challenging. Property variations may be described on many scales, and the information available from measurements reflect different scales. In fact, experiments on laboratory core samples, well-log data, well-test data, and reservoir-production data all represent information potentially valuable to reservoir characterization, yet they all reflect information about spatial variations of properties at different scales. Nuclear magnetic resonance (NMR) spectroscopy and imaging (MRI) provide enormous potential for developing new descriptions and understandings of heterogeneous media. NMR has the rare capability to probe permeable media non-invasively, with spatial resolution, and it provides unique information about molecular motions and interactions that are sensitive to morphology. NMR well-logging provides the best opportunity ever to resolve permeability distributions within petroleum reservoirs. We develop MRI methods to determine, for the first time, spatially resolved distributions of porosity and permeability within permeable media samples that approach the intrinsic scale: the finest resolution of these macroscopic properties possible. To our knowledge, this is the first time that the permeability is actually resolved at a scale smaller than the sample. In order to do this, we have developed a robust method to determine of relaxation distributions from NMR experiments and a novel implementation and analysis of MRI experiments to determine the amount of fluid corresponding to imaging regions, which are in turn used to determine porosity and saturation distributions. We have developed a novel MRI experiment to determine velocity distributions within flowing experiments, and developed methodology using that data to determine spatially resolved permeability distributions. We investigate the use of intrinsic properties for developing improved correlations for predicting permeability from NMR well-logging data and for obtaining more accurate estimates of multiphase flow properties--the relative permeability and capillary pressure--from displacement experiments. We demonstrate the use of MRI measurements of saturation and relaxation for prediction wetting-phase relative permeability for unstable experiments. Finally, we developed an improved method for determining surface relaxivity with NMR experiments, which can provide better descriptions of permeable media microstructures and improved correlations for permeability predictions.

C.T. Philip Chang; Changho Choi; Jeromy T. Hollenshead; Rudi Michalak; Jack Phan; Ramon Saavedra; John C. Slattery; Jinsoo Uh; Randi Valestrand; A. Ted Watson; Song Xue

2005-01-01T23:59:59.000Z

375

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

SciTech Connect (OSTI)

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.

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

2008-02-01T23:59:59.000Z

376

Characterization of oil and gas reservoir heterogeneity; Final report, November 1, 1989--June 30, 1993  

SciTech Connect (OSTI)

The Alaskan North Slope comprises one of the Nation`s and the world`s most prolific oil province. Original oil in place (OOIP) is estimated at nearly 70 BBL (Kamath and Sharma, 1986). Generalized reservoir descriptions have been completed by the University of Alaska`s Petroleum Development Laboratory over North Slope`s major fields. These fields include West Sak (20 BBL OOIP), Ugnu (15 BBL OOIP), Prudhoe Bay (23 BBL OOIP), Kuparuk (5.5 BBL OOIP), Milne Point (3 BBL OOIP), and Endicott (1 BBL OOIP). Reservoir description has included the acquisition of open hole log data from the Alaska Oil and Gas Conservation Commission (AOGCC), computerized well log analysis using state-of-the-art computers, and integration of geologic and logging data. The studies pertaining to fluid characterization described in this report include: experimental study of asphaltene precipitation for enriched gases, CO{sup 2} and West Sak crude system, modeling of asphaltene equilibria including homogeneous as well as polydispersed thermodynamic models, effect of asphaltene deposition on rock-fluid properties, fluid properties of some Alaskan north slope reservoirs. Finally, the last chapter summarizes the reservoir heterogeneity classification system for TORIS and TORIS database.

Sharma, G.D.

1993-09-01T23:59:59.000Z

377

Control rod worth and related nuclear characteristics of an axially heterogeneous liquidmetal fast breeder reactor core  

SciTech Connect (OSTI)

An axially heterogeneous core (AHC) concept is applied to a 1000-MW(electric)-class tank-type liquidmetal fast breeder reactor (LMFBR). This AHC is characterized by a disk-shaped internal blanket with a radial thickness adjustment at the core midplane. The nuclear characteristics connected with control rod worth of the AHC are analyzed and compared with those of a homogeneous core (HOC) of the same power rating. The neutronics analysis shows that the reactivity insertion due to the vertical displacement of control rods relative to the core, which is an important safety characteristic of a tank-type LMFBR core, is significantly decreased in the AHC because of the reduced control worth requirement and smaller peakto-average differential worth in the primary control system. This allows the AHC to have a vertical displacement 50% greater than that of the HOC and may offer less rigid design conditions for roof slab stiffness and core support systems in a tank-type LMFBR. A reduction in the number of primary control rods is also possible because of a smaller control worth requirement and a better power peaking factor. The work was sponsored by a federation of Japanese electric power companies and performed under the guidance of the fast breeder reactor project office.

Kawashima, K.; Inayaki, T.; Inoue, K.; Kaneto, K.

1985-08-01T23:59:59.000Z

378

Characterization of opiate receptor heterogeneity using affinity ligands and phospholipase A/sub 2/  

SciTech Connect (OSTI)

The primary aim of the dissertation was to study the heterogeneity of opiate receptors by utilizing affinity ligands, and by modification of the receptor lipid-microenvironment with phospholipase A/sub 2/ (PLA/sub 2/). The affinity ligands, 14-bromacetamidomorphine (BAM) and 14-chloroacetylnaltrexone (CAN), selectively inactivated high affinity dihydromorphine binding sites in an apparently irreversible manner (the inhibition was resistant to extensive washes of treated neural membrane homogenates). The inhibitory effect of PLA/sub 2/ (10 ng/ml) on opiate receptor subtypes was determined using (/sup 3/H)-dihydromorphine (..mu..-type agonist), (/sup 3/H)-enkephalin (delta agonist) and (/sup 3/H)-naloxone (..mu.. antagonist). PLA/sub 2/ abolished the high affinity antagonist binding site, whereas it inhibited high and low affinity agonist binding sites similarly. The results suggest that high affinity antagonist binding sites are different from high affinity agonist binding sites. Indirect binding assays demonstrated that the selectivities of ..mu..- and delta receptors are not affected significantly by PLA/sub 2/ treatment.

Reichman, M.

1985-01-01T23:59:59.000Z

379

Effect of high pressure homogenization on the milk fat globule membrane and its relation with the emulsion stability of milk  

E-Print Network [OSTI]

pressure and heating temperature. Emulsion stability of milk increased with increased homogenization pressure and heat treatment, but was not affected by the milk fat concentrations used. Homogenization of milk increased the milk fat surface area...

Cano Ruiz, Maria Elena

1996-01-01T23:59:59.000Z

380

Catalyst system comprising a first catalyst system tethered to a supported catalyst  

DOE Patents [OSTI]

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.

Angelici, R.J.; Gao, H.

1998-08-04T23:59:59.000Z

Note: This page contains sample records for the topic "homogeneous catalysis heterogeneous" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


381

Homogeneous Factorisations of Graphs and Michael Giudici a, Cai Heng Li a  

E-Print Network [OSTI]

Homogeneous Factorisations of Graphs and Digraphs Michael Giudici a, Cai Heng Li a Primoz Potocnik@maths.uwa.edu.au (Michael Giudici), li@maths.uwa.edu.au (Cai Heng Li), primoz.potocnik@fmf.uni-lj.si (Primoz Preprint

Giudici, Michael

382

Molecular simulation study of homogeneous crystal nucleation in n-alkane melts  

E-Print Network [OSTI]

This work used molecular dynamics (MD) and Monte Carlo (MC) method to study the homogeneous crystal nucleation in the melts of n-alkanes, the simplest class of chain molecules. Three n-alkanes with progressive chain length ...

Yi, Peng, Ph. D. Massachusetts Institute of Technology

2011-01-01T23:59:59.000Z

383

Analysis of combustion in a small homogeneous charge compression assisted ignition engine  

E-Print Network [OSTI]

characteristics to homogeneous charge compression ignition (HCCI) engines. Difficulties such as unknown ignition.raine@auckland.ac.nz geneous charge compression ignition (HCCI) engines. JER03805 © IMechE 2006 Int. J. Engine Res. Vol. 7 #12

384

Extension of the high load limit in the Homogeneous Charge Compression Ignition engine  

E-Print Network [OSTI]

The Homogeneous Charge Compression Ignition (HCCI) engine offers diesel-like efficiency with very low soot and NOx emissions. In a HCCI engine, a premixed charge of air, fuel and burned gas is compressed to achieve ...

Scaringe, Robert J. (Robert Joseph)

2009-01-01T23:59:59.000Z

385

Rank and Set Restrictions for Homogeneity Analysis in R: The "homals" Package  

E-Print Network [OSTI]

Rank and Set Restrictions for Homogeneity Analysis in R:various extensions in terms of rank restrictions (nonlinearSection 2.1) in terms of rank restrictions (Section 2.2) and

Mair, Patrick; Leeuw, Jan de

2008-01-01T23:59:59.000Z

386

Rank and Set Restrictions for Homogeneity Analysis in R: The "homals" Package  

E-Print Network [OSTI]

Rank and Set Restrictions for Homogeneity Analysis in R:various extensions in terms of rank restrictions (nonlinearSection 2.1) in terms of rank restrictions (Section 2.2) and

Patrick Mair; Jan de Leeuw

2011-01-01T23:59:59.000Z

387

RATE OF STRAIN TENSOR STATISTICS IN COMPRESSIBLE HOMOGENEOUS G. Erlebacher 1 , S. Sarkar 1  

E-Print Network [OSTI]

RATE OF STRAIN TENSOR STATISTICS IN COMPRESSIBLE HOMOGENEOUS TURBULENCE G. Erlebacher 1 , S. Sarkar was determined in Sarkar, Erlebacher and Hus­ saini (ref. 2) to be due to enhanced compressible dis­ sipation

Erlebacher, Gordon

388

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

E-Print Network [OSTI]

THE EFFECT OF TEMPERATURE AND HOMOGENIZATION PRESSURE ON ENZYMATIC ACTIVITY IN CHEESE WHEY A Thesis by MARIA YANINA DEL CAWvKN Submitted to the Office of Graduate Studies of Texas A&M University in partial fulfillment of the requirement... for the degree of MASTER OF SCIENCE August 1995 Major Subject; Food Science and Technology THE EFFECT OF TEMPERATURE AND HOMOGENIZATION PRESSURE ON ENZYMATIC ACTIVITY IN CHEESE WHEY A Thesis by MARIA YANINA DEL CARMEN Submitted to the Office of Graduate...

Del Carmen, Maria Yanina

1995-01-01T23:59:59.000Z

389

Integration of geodesic flows on homogeneous spaces: the case of a wild lie group  

E-Print Network [OSTI]

We obtain necessary and sufficient conditions for the integrability in quadratures of geodesic flows on homogeneous spaces $M$ with invariant and central metrics. The proposed integration algorithm consists in using a special canonical transformation in the space $T^*M$ based on constructing the canonical coordinates on the orbits of the coadjoint representation and on the simplectic sheets of the Poisson algebra of invariant functions. This algorithm is applicable to integrating geodesic flows on homogeneous spaces of a wild Lie group.

A. A. Magazev; I. V. Shirokov

2007-03-21T23:59:59.000Z

390

Two dimensional finite element analysis of homogenization and failure in plain weave textile composites  

E-Print Network [OSTI]

TWO DIMENSIONAL FINITE ELEMENT ANALYSIS OF HOMOGENIZATION AND FAILURE IN PLAIN WEAVE TEXTILE COMPOSITES A Thesis by VEERARAGHAVA GOPAL KONDAGUNTA Submitted to the Office of Graduate Studies of Texas ARM University In partial fulffllment... of the requirements for the degree of MASTER OF SCIENCE August 1993 Major Subject: Aerospace Engineering TWO DIMENSIONAL FINITE ELEMENT ANALYSIS OF HOMOGENIZATION AND FAILURE IN PLAIN WEAVE TEXTILE COMPOSITES A Thesis by VEERARAGHAVA GOPAL KONDAGUNTA...

Kondagunta, Veeraraghava Gopal

1993-01-01T23:59:59.000Z

391

Feedbacks between hydrological heterogeneity and bioremediation induced biogeochemical transformations  

SciTech Connect (OSTI)

For guiding optimal design and interpretation of in-situ treatments that strongly perturb subsurface systems, knowledge about the spatial and temporal patterns of mass transport and reaction intensities are important. Here, a procedure was developed and applied to time-lapse concentrations of a conservative tracer (bromide), an injected amendment (acetate) and reactive species (iron(II), uranium(VI) and sulfate) associated with two field scale biostimulation experiments, which were conducted successively at the same field location over two years. The procedure is based on a temporal moment analysis approach that relies on a streamtube approximation. The study shows that biostimulated reactions can be considerably influenced by subsurface hydrological and geochemical heterogeneities: the delivery of bromide and acetate and the intensity of the sulfate reduction is interpreted to be predominantly driven by the hydrological heterogeneity, while the intensity of the iron reduction is interpreted to be primarily controlled by the geochemical heterogeneity. The intensity of the uranium(VI) reduction appears to be impacted by both the hydrological and geochemical heterogeneity. Finally, the study documents the existence of feedbacks between hydrological heterogeneity and remediation-induced biogeochemical transformations at the field scale, particularly the development of precipitates that may cause clogging and flow rerouting.

Englert, A.; Hubbard, S.S.; Williams, K.H.; Li, L.; Steefel, C.I.

2009-04-15T23:59:59.000Z

392

Acoustic excitations and elastic heterogeneities in disordered solids  

E-Print Network [OSTI]

In the recent years, much attention has been devoted to the inhomogeneous nature of the mechanical response at the nano-scale in disordered solids. Clearly, the elastic heterogeneities that have been characterized in this context are expected to strongly impact the nature of the sound waves which, in contrast to the case of perfect crystals, cannot be completely rationalized in terms of phonons. Building on previous work on a toy model showing an amorphisation transition [Mizuno H, Mossa S, Barrat JL (2013) EPL {\\bf 104}:56001], we investigate the relationship between sound waves and elastic heterogeneities in a unified framework, by continuously interpolating from the perfect crystal, through increasingly defective phases, to fully developed glasses. We provide strong evidence of a direct correlation between sound waves features and the extent of the heterogeneous mechanical response at the nano-scale.

Hideyuki Mizuno; Stefano Mossa; Jean-Louis Barrat

2014-03-26T23:59:59.000Z

393

A lattice mesoscopic model of dynamically heterogeneous fluids  

E-Print Network [OSTI]

We introduce a mesoscopic three-dimensional Lattice Boltzmann Model which attempts to mimick the physical features associated with cage effects in dynamically heterogeneous fluids. To this purpose, we extend the standard Lattice Boltzmann dynamics with self-consistent constraints based on the non-local density of the surrounding fluid. The resulting dynamics exhibits typical features of dynamic heterogeneous fluids, such as non-Gaussian density distributions and long-time relaxation. Due to its intrinsically parallel dynamics, and absence of statistical noise, the method is expected to compute significantly faster than molecular dynamics, Monte Carlo and lattice glass models.

A. Lamura; S. Succi

2005-10-04T23:59:59.000Z

394

Fractal Dimensions of a Weakly Clustered Distribution and the Scale of Homogeneity  

E-Print Network [OSTI]

Homogeneity and isotropy of the universe at sufficiently large scales is a fundamental premise on which modern cosmology is based. Fractal dimensions of matter distribution is a parameter that can be used to test the hypothesis of homogeneity. In this method, galaxies are used as tracers of the distribution of matter and samples derived from various galaxy redshift surveys have been used to determine the scale of homogeneity in the Universe. Ideally, for homogeneity, the distribution should be a mono-fractal with the fractal dimension equal to the ambient dimension. While this ideal definition is true for infinitely large point sets, this may not be realised as in practice, we have only a finite point set. The correct benchmark for realistic data sets is a homogeneous distribution of a finite number of points and this should be used in place of the mathematically defined fractal dimension for infinite number of points (D) as a requirement for approach towards homogeneity. We derive the expected fractal dimension for a homogeneous distribution of a finite number of points. We show that for sufficiently large data sets the expected fractal dimension approaches D in absence of clustering. It is also important to take the weak, but non-zero amplitude of clustering at very large scales into account. In this paper we also compute the expected fractal dimension for a finite point set that is weakly clustered. Clustering introduces departures in the Fractal dimensions from D and in most situations the departures are small if the amplitude of clustering is small. Features in the two point correlation function, like those introduced by Baryon Acoustic Oscillations (BAO) can lead to non-trivial variations in the Fractal dimensions where the amplitude of clustering and deviations from D are no longer related in a monotonic manner.

J. S. Bagla; Jaswant Yadav; T. R. Seshadri

2008-08-04T23:59:59.000Z

395

Poly(3,4-ethylenedioxypyrrole) Modified Emitter Electrode for Substitution of Homogeneous Redox Buffer Agent Hydroquinone in Electrospray Ionization Mass Spectrometry  

SciTech Connect (OSTI)

The electrolysis inherent to the operation of the electrospray ionization (ESI) source used with mass spectrometry (MS) is a well-known attendant effect of generating unipolar spray droplets and may affect the analysis of the analyte of interest. Undesirable electrolysis of an analyte may be prevented by limiting the emitter electrode current and/or the mass transport characteristics of the system. However, these ways to avoid analyte electrolysis may not be applcable in all ESI-MS experiments. For example, in the case of specific nanospray systems (e.g. the wire-in-a-capillary bulk-loaded or chip-based tip-loaded nanospray configurations), the solution flow rate is fixed in the 50-500 nL/min range and the electrode surface to volume ratio is large presenting a very effcient analyte to electrode mass transport configuration. In these situations, control over the interfacial potential of the working electrode via homogeneous or traditional heterogeneous (sacrificial metal) redox buffering is a possible way to prevent analyte electrolysis. However, byproducts of these redox buffering approaches can appear in the mass spectra and/or they can chemically alter the analyte. For example, the main reason for using hydroquinone as a homogeneous redox buffer, in addition to its relatively low oxidation potential, is that neither the original compound nor its oxidation product benzoquinone can be detected directly by ESI-MS. However, benzoquinone can alter analytes with thiol functional groups by reacting with those groups via a 1,4-Michael addition.

Peintler-Krivan, Emese [ORNL; Van Berkel, Gary J [ORNL; Kertesz, Vilmos [ORNL

2010-01-01T23:59:59.000Z

396

Crystal Structure of (+)-[delta]-Cadinene Synthase from Gossypium arboreum and Evolutionary Divergence of Metal Binding Motifs for Catalysis  

SciTech Connect (OSTI)

(+)-{delta}-Cadinene synthase (DCS) from Gossypium arboreum (tree cotton) is a sesquiterpene cyclase that catalyzes the cyclization of farnesyl diphosphate in the first committed step of the biosynthesis of gossypol, a phytoalexin that defends the plant from bacterial and fungal pathogens. Here, we report the X-ray crystal structure of unliganded DCS at 2.4 {angstrom} resolution and the structure of its complex with three putative Mg{sup 2+} ions and the substrate analogue inhibitor 2-fluorofarnesyl diphosphate (2F-FPP) at 2.75 {angstrom} resolution. These structures illuminate unusual features that accommodate the trinuclear metal cluster required for substrate binding and catalysis. Like other terpenoid cyclases, DCS contains a characteristic aspartate-rich D{sup 307}DTYD{sup 311} motif on helix D that interacts with Mg{sub A}{sup 2+} and Mg{sub C}{sup 2+}. However, DCS appears to be unique among terpenoid cyclases in that it does not contain the 'NSE/DTE' motif on helix H that specifically chelates Mg{sub B}{sup 2+}, which is usually found as the signature sequence (N,D)D(L,I,V)X(S,T)XXXE (boldface indicates Mg{sub B}{sup 2+} ligands). Instead, DCS contains a second aspartate-rich motif, D{sup 451}DVAE{sup 455}, that interacts with Mg{sub B}{sup 2+}. In this regard, DCS is more similar to the isoprenoid chain elongation enzyme farnesyl diphosphate synthase, which also contains two aspartate-rich motifs, rather than the greater family of terpenoid cyclases. Nevertheless, the structure of the DCS-2F-FPP complex shows that the structure of the trinuclear magnesium cluster is generally similar to that of other terpenoid cyclases despite the alternative Mg{sub B}{sup 2+} binding motif. Analyses of DCS mutants with alanine substitutions in the D{sup 307}DTYD{sup 311} and D{sup 451}DVAE{sup 455} segments reveal the contributions of these segments to catalysis.

Gennadios, Heather A.; Gonzalez, Veronica; Di Costanzo, Luigi; Li, Amang; Yu, Fanglei; Miller, David J.; Allemann, Rudolf K.; Christianson, David W.; (UPENN); (Cardiff); (UC)

2009-09-11T23:59:59.000Z

397

"Modeling Heterogeneous Catalytic Reactions: From the Molecular Process to the Technical System"  

E-Print Network [OSTI]

rapidly growing demand for more efficient exploitation of energy and materials resources. As in many other gas phase. Due to the highly activated nature of many of the involved elementary steps every-day products, catalysis has always been the driv- ing force for chemical industries. In the 21st

398

Hydrocarbons Heterogeneous Pyrolysis: Experiments and Modeling for Scramjet Thermal Management  

E-Print Network [OSTI]

1 Hydrocarbons Heterogeneous Pyrolysis: Experiments and Modeling for Scramjet Thermal Management : United States (2008)" #12;2 I. Introduction One of the main issues of the development of scramjet, an air to the endothermicity of its thermal decomposition. Because of the large heat load found in a scramjet, engine

Paris-Sud XI, Université de

399

Reliability of Heterogeneous Distributed Computing Systems in the Presence  

E-Print Network [OSTI]

Reliability of Heterogeneous Distributed Computing Systems in the Presence of Correlated Failures Jorge E. Pezoa, Member, IEEE and Majeed M. Hayat, Fellow, IEEE Abstract--While the reliability) fail independently, the impact of correlated failures of CEs on the reliability remains an open

Hayat, Majeed M.

400

PerCon: A Personal Digital Library for Heterogeneous Data  

E-Print Network [OSTI]

PerCon: A Personal Digital Library for Heterogeneous Data Su Inn Park, Frank Shipman Center a personal digital library of data. Users may then search, browse, visualize and annotate the data stages of exploratory research. We liken these personal and small group data collections to personal book

Shipman, Frank

Note: This page contains sample records for the topic "homogeneous catalysis heterogeneous" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


401

A Gossip Algorithm for Heterogeneous Multi-Vehicle Routing Problems  

E-Print Network [OSTI]

tasks arbitrarily distributed in a plane, to each task is assigned a servicing cost, each vehicle with arbi- trary execution cost and vehicles with different task exe- cution speeds. We provide upperA Gossip Algorithm for Heterogeneous Multi-Vehicle Routing Problems Mauro Franceschelli Daniele

Bullo, Francesco

402

TURBULENT SHEAR STRESS IN HETEROGENEOUS SEDIMENT-LADEN FLOWS  

E-Print Network [OSTI]

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

Julien, Pierre Y.

403

Effect of Land Surface Heterogeneity on Satellite Near-  

E-Print Network [OSTI]

in regulating the energy and water balance at the soil surface and it is therefore a crucial variable for many. SMOS will carry an L-band (1.4GHz) microwave radiometer and will provide near-surface soil moisture highly heterogeneous land surface conditions. The principal objectives of this research are to (i) test

Walker, Jeff

404

Uni ed Support for Heterogeneous Security Policies in Distributed Systems  

E-Print Network [OSTI]

Uni ed Support for Heterogeneous Security Policies in Distributed Systems Naftaly H. Minsky in this paper a security mechanism that can support e ciently, and in a uni ed manner, a wide range of security policies are de ned formallyandexplicitly,and are enforced bya uni ed mechanism. Each policy under

Minsky, Naftaly

405

Energy Consumption Characteriation of Heterogeneous Servers School of Computer Science  

E-Print Network [OSTI]

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

Qin, Xiao

406

Chimera states in heterogeneous networks Carlo R. Laing  

E-Print Network [OSTI]

Chimera states in heterogeneous networks Carlo R. Laing Institute of Information and Mathematical Chimera states in networks of coupled oscillators occur when some fraction of the oscillators synchronise with one another, while the remaining oscillators are incoherent. Several groups have studied chimerae

Laing, Carlo R.

407

Autonomous Demand Response in Heterogeneous Smart Grid Topologies  

E-Print Network [OSTI]

, heterogeneous grid, locational marginal price, game theory, Nash equilibrium. I. INTRODUCTION Demand response on locational marginal prices (LMPs), which depend on parameters such as the line c appliances such as air-conditioners and water-heaters [2]. An alternative for DLC is smart pricing, where

Mohsenian-Rad, Hamed

408

Energy-Efficient Computing with Heterogeneous Multi-Cores  

E-Print Network [OSTI]

Energy-Efficient Computing with Heterogeneous Multi-Cores Tulika Mitra School of Computing National the application can be exploited leading to faster and energy-efficient computing. This paper describes of such architectures for improved energy-efficiency. I. INTRODUCTION The past decade has witnessed an unprecedented

Mitra, Tulika

409

Nucleotide Specificity versus Complex Heterogeneity in Exonuclease Activity Measurements  

E-Print Network [OSTI]

Nucleotide Specificity versus Complex Heterogeneity in Exonuclease Activity Measurements Jo activity is nucleotide-dependent, and that a fluorescent label bound to a nucleotide significantly slows are fluorescently labeled at two specific sites in the nucleotide sequence (positions 5 and 38 from the free end

Enderlein, Jörg

410

a Modular, Multi-Engine Simulator for Heterogeneous Swarm Robotics  

E-Print Network [OSTI]

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

Libre de Bruxelles, Université

411

Nanoscale Heterogeneity of Polyamide Membranes Formed by Interfacial Polymerization  

E-Print Network [OSTI]

Nanoscale Heterogeneity of Polyamide Membranes Formed by Interfacial Polymerization Viatcheslav theoretical model of polyamide membrane formation via interfacial polymerization. 1. Introduction Polyamide of a microporous support (most often polysulfone) by means of interfacial polymerization (IP).3,4 The latter method

Freger, Viatcheslav "Slava"

412

A Dynamic Matching and Scheduling Algorithm for Heterogeneous Computing Systems  

E-Print Network [OSTI]

A heterogeneous computing system provides a variety of different machines, orchestrated to perform an application Maheswaran and Howard Jay Siegel Parallel Processing Laboratory School of Electrical and Computer Engineering whose subtasks have diverse execution requirements. The subtasks must be assigned to machines (matching

413

Power-Aware Dynamic Task Scheduling for Heterogeneous Accelerated Clusters  

E-Print Network [OSTI]

Power-Aware Dynamic Task Scheduling for Heterogeneous Accelerated Clusters Tomoaki Hamano, Toshio Endo and Satoshi Matsuoka Tokyo Institute of Technology/JST, Japan Abstract Recent accelerators with accelerators and general CPUs are becoming popular, such as LANL's Roadrun- ner and our own TSUBAME

414

Examining Energy Use in Heterogeneous Archival Storage Systems  

E-Print Network [OSTI]

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

Polyzotis, Neoklis (Alkis)

415

Towards Cooperation of Heterogeneous, Autonomous Robots: A Case Study of  

E-Print Network [OSTI]

in industrial and research applications the need to execute successfully challenging missions and tasks has also computing capabil- ities. Several applications have been investigated with robots, which differ only are classified as weakly or strongly heterogeneous. An application with a strongly heteroge- neous robot team has

Stryk, Oskar von

416

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

417

Anthropogenic Biomes ver. 1 Anthropogenic biomes represent heterogeneous  

E-Print Network [OSTI]

defined by population density and vegetation cover. The 21 biomes are grouped into six major categoriesAnthropogenic Biomes ver. 1 Africa Anthropogenic biomes represent heterogeneous landscape mosaics: Populated irrigated cropland 34: Populated rainfed cropland 35: Remote croplands 41: Residential rangelands

Columbia University

418

A Resources Virtualization Approach Supporting Uniform Access to Heterogeneous  

E-Print Network [OSTI]

A Resources Virtualization Approach Supporting Uniform Access to Heterogeneous Grid Resources1 of resources such as computing resources, storage resources, instrument resources, data resources, etc. However, because of the differences of formats, descriptions, structures, and access modes of these resources, grid

Keinan, Alon

419

An analysis and hypothesis generation platform for heterogeneous cancer  

E-Print Network [OSTI]

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

Reed, Chris

420

Coordinated Output Regulation of Multiple Heterogeneous Linear Systems  

E-Print Network [OSTI]

, the generalizations of coordination of multiple linear dynamic systems to the cooperative output regulation problemCoordinated Output Regulation of Multiple Heterogeneous Linear Systems Ziyang Meng, Tao Yang, Dimos V. Dimarogonas, and Karl H. Johansson Abstract-- The coordinated output regulation problem

Dimarogonas, Dimos

Note: This page contains sample records for the topic "homogeneous catalysis heterogeneous" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


421

Cellubrevin-targeted Fluorescence Uncovers Heterogeneity in the Recycling Endosomes*  

E-Print Network [OSTI]

Cellubrevin-targeted Fluorescence Uncovers Heterogeneity in the Recycling Endosomes* (Received, University of California, Berkeley, California 94720-3200 The pH and trafficking of recycling endosomes have-enriched recycling endosomes (pHCb) and FITC-transferrin to measure the pH of transferrin- enriched recycling

Machen, Terry E.

422

Measuring Heterogeneity in Forensic Databases Using Hierarchical Bayes Models  

E-Print Network [OSTI]

Measuring Heterogeneity in Forensic Databases Using Hierarchical Bayes Models By Kathryn Roeder, as currently defined, do not uniquely identify individuals. For criminal cases involving DNA evidence, forensic­ ing profiles are based on reference populations maintained by forensic testing laboratories. Each

423

Homogenous charge compression ignition engine having a cylinder including a high compression space  

DOE Patents [OSTI]

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.

Agama, Jorge R.; Fiveland, Scott B.; Maloney, Ronald P.; Faletti, James J.; Clarke, John M.

2003-12-30T23:59:59.000Z

424

A cell model for homogenization of fiber-reinforced composites: General theory and nonlinear elasticity effects  

SciTech Connect (OSTI)

The theoretical basis of the homogenization technique developed by Aboudi is presented and assessed. Given the constitutive relations of the constituents, this technique provides an equivalent, homogeneous, constitutive model of unidirectional, continuous-fiber-reinforced composites. The expressions that comprise the first-order version of the technique are given special attention as this treatment has considerable practical value. Nonlinear elasticity effects are added to it. This extension increases the accuracy of numerical simulations of high strain-rate loadings. It is particularly important for any dynamic loading in which shock waves might be produced, including crash safety, armor, and munitions applications. Examples illustrate that elastic nonlinearity can make substantial contributions at strains of only a few per cent. These contributions are greatest during post-yield inelastic deformation. The micromechanics-based homogenization technique is shown to facilitate use of an efficient approximate treatment of elastic nonlinearity in composites with isotropic matrix materials.

Aidun, J.B.; Addessio, F.L.

1995-11-01T23:59:59.000Z

425

Characterization of oil and gas reservoir heterogeneity. Final report  

SciTech Connect (OSTI)

Research described In this report addresses the internal architecture of two specific reservoir types: restricted-platform carbonates and fluvial-deltaic sandstones. Together, these two reservoir types contain more than two-thirds of the unrecovered mobile oil remaining ill Texas. The approach followed in this study was to develop a strong understanding of the styles of heterogeneity of these reservoir types based on a detailed outcrop description and a translation of these findings into optimized recovery strategies in select subsurface analogs. Research targeted Grayburg Formation restricted-platform carbonate outcrops along the Algerita Escarpment and In Stone Canyon In southeastern New Mexico and Ferron deltaic sandstones in central Utah as analogs for the North Foster (Grayburg) and Lake Creek (Wilcox) units, respectively. In both settings, sequence-stratigraphic style profoundly influenced between-well architectural fabric and permeability structure. It is concluded that reservoirs of different depositional origins can therefore be categorized Into a ``heterogeneity matrix`` based on varying intensity of vertical and lateral heterogeneity. The utility of the matrix is that it allows prediction of the nature and location of remaining mobile oil. Highly stratified reservoirs such as the Grayburg, for example, will contain a large proportion of vertically bypassed oil; thus, an appropriate recovery strategy will be waterflood optimization and profile modification. Laterally heterogeneous reservoirs such as deltaic distributary systems would benefit from targeted infill drilling (possibly with horizontal wells) and improved areal sweep efficiency. Potential for advanced recovery of remaining mobile oil through heterogeneity-based advanced secondary recovery strategies In Texas is projected to be an Incremental 16 Bbbl. In the Lower 48 States this target may be as much as 45 Bbbl at low to moderate oil prices over the near- to mid-term.

Tyler, N.; Barton, M.D.; Bebout, D.G.; Fisher, R.S.; Grigsby, J.D.; Guevara, E.; Holtz, M.; Kerans, C.; Nance, H.S.; Levey, R.A.

1992-10-01T23:59:59.000Z

426

EVIDENCE FOR MAGNESIUM ISOTOPE HETEROGENEITY IN THE SOLAR PROTOPLANETARY DISK  

SciTech Connect (OSTI)

With a half-life of 0.73 Myr, the {sup 26}Al-to-{sup 26}Mg decay system is the most widely used short-lived chronometer for understanding the formation and earliest evolution of the solar protoplanetary disk. However, the validity of {sup 26}Al-{sup 26}Mg ages of meteorites and their components relies on the critical assumption that the canonical {sup 26}Al/{sup 27}Al ratio of {approx}5 x 10{sup -5} recorded by the oldest dated solids, calcium-aluminium-rich inclusions (CAIs), represents the initial abundance of {sup 26}Al for the solar system as a whole. Here, we report high-precision Mg-isotope measurements of inner solar system solids, asteroids, and planets demonstrating the existence of widespread heterogeneity in the mass-independent {sup 26}Mg composition ({mu}{sup 26}Mg*) of bulk solar system reservoirs with solar or near-solar Al/Mg ratios. This variability may represent heterogeneity in the initial abundance of {sup 26}Al across the solar protoplanetary disk at the time of CAI formation and/or Mg-isotope heterogeneity. By comparing the U-Pb and {sup 26}Al-{sup 26}Mg ages of pristine solar system materials, we infer that the bulk of the {mu}{sup 26}Mg* variability reflects heterogeneity in the initial abundance of {sup 26}Al across the solar protoplanetary disk. We conclude that the canonical value of {approx}5 x 10{sup -5} represents the average initial abundance of {sup 26}Al only in the CAI-forming region, and that large-scale heterogeneity-perhaps up to 80% of the canonical value-may have existed throughout the inner solar system. If correct, our interpretation of the Mg-isotope composition of inner solar system objects precludes the use of the {sup 26}Al-{sup 26}Mg system as an accurate early solar system chronometer.

Larsen, Kirsten K.; Trinquier, Anne; Paton, Chad; Schiller, Martin; Wielandt, Daniel; Connelly, James N.; Nordlund, Ake; Krot, Alexander N.; Bizzarro, Martin [Centre for Star and Planet Formation, Natural History Museum of Denmark, University of Copenhagen, Copenhagen DK-1350 (Denmark); Ivanova, Marina A. [Vernadsky Institute of Geochemistry and Analytical Chemistry, Moscow 119991 (Russian Federation)

2011-07-10T23:59:59.000Z

427

Future geodesic completeness of some spatially homogeneous solutions of the vacuum Einstein equations in higher dimensions  

E-Print Network [OSTI]

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.

Arne Goedeke; Alan D. Rendall

2010-02-21T23:59:59.000Z

428

Two stroke homogenous charge compression ignition engine with pulsed air supplier  

DOE Patents [OSTI]

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.

Clarke, John M. (Chillicothe, IL)

2003-08-05T23:59:59.000Z

429

Enhancement of crystal homogeneity of protein crystals under application of an external alternating current electric field  

SciTech Connect (OSTI)

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.

Koizumi, H.; Uda, S.; Fujiwara, K.; Nozawa, J. [Institute for Materials Research, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai, 980-8577 (Japan); Tachibana, M. [Graduate School of Nanobioscience, Yokohama City University, 22-2 Seto, Kanazawa-ku, Yokohama, 236-0027 (Japan); Kojima, K. [Department of Education, Yokohama Soei University, 1 Miho-tyou, Midori-ku, Yokohama, 226-0015 (Japan)

2014-10-06T23:59:59.000Z

430

Federating Distributed and Heterogeneous Information Sources in Neuroimaging: The NeuroBase Project Federating Distributed and Heterogeneous In-  

E-Print Network [OSTI]

Federating Distributed and Heterogeneous Information Sources in Neuroimaging: The NeuroBase ProjectBase Project C. Barillot1 , H. Benali2 , M. Dojat4 , A. Gaignard1 , B. Gibaud1 , S. Kinkingnéhun2 , J Sources in Neuroimaging: The NeuroBase Project C. Barillot1 , H. Benali2 , M. Dojat3 , A. Gaignard1 , B

Boyer, Edmond

431

AN AUTOMATED SYSTEM FOR SYSTEMATIC TESTING OF LOCOMOTION ON HETEROGENEOUS GRANULAR MEDIA*  

E-Print Network [OSTI]

robotic locomotors like PackBot or RHex (Figure 1a) travel across these "flowable" types of terrain [1]). Figure 1 Natural heterogeneous terrain. (a) RHex robot traveling across heterogeneous gravel substrate

Goldman, Daniel I.

432

A theoretical and empirical exploration into the heterogeneous fragility of Chilean firms and workplaces  

E-Print Network [OSTI]

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 ...

Landerretche, Oscar

2006-01-01T23:59:59.000Z

433

Hybrid Dynamic Energy and Thermal Management in Heterogeneous Embedded Multiprocessor SoCs  

E-Print Network [OSTI]

Hybrid Dynamic Energy and Thermal Management in Heterogeneous Embedded Multiprocessor SoCs Shervin propose a joint thermal and energy management technique specifically designed for heterogeneous MPSo technique simultaneously reduces the thermal hot spots, temperature gradients, and energy consumption

Simunic, Tajana

434

Value or Growth? Pricing of Idiosyncratic Cash Flow Risk with Heterogeneous Beliefs  

E-Print Network [OSTI]

We study an equilibrium continuous-time exchange economy where idiosyncratic cash flow risks are priced via investors' heterogeneous beliefs. Investors perceive idiosyncratic cash flow risks differently through heterogeneous subjective mean growth...

Jhang, Ho Gyu

2014-05-05T23:59:59.000Z

435

Geology, compositional heterogeneities, and geochemical origin of the Yacheng gas field, Qiongdongnan Basin, South China Sea  

SciTech Connect (OSTI)

The Yacheng gas field is located in the footwall of the No. 1 fault, the boundary fault between the Yinggehai and Qiongdongnan basins. All strata are normally pressured in the gas field except for the Meishan Formation. The Meishan Formation is overpressured near the No. 1 fault in the gas field and in the adjacent Yinggehai Basin. An obvious thermal anomaly occurs below 3600 m in the gas field. This anomaly, characterized by an abrupt increase in drill-stem test and fluid-inclusion homogenization temperatures, vitrinite reflectance (R{sub o}), and Rock-Eval T{sub max}, and by an abnormally low temperature/R{sub o}/T{sub max} gradient, diminishes away from the Yinggehai Basin. The gases and condensates have abnormally high aromatic hydrocarbon contents and show obvious heterogeneities. Away from the No. 1 fault, the C{sub 2+} hydrocarbon content and C{sub 2+}/{Sigma}C{sub n} increase; carbon dioxide content decreases; {delta}{sup 13}C values for methane, ethane, and carbon dioxide become lighter; the heptane and isoheptane values decrease; and the relative contents of aromatic hydrocarbons, both in C{sub 6}/C{sub 7} light hydrocarbons and in the condensates, decrease. The gas field was charged from both the Qiongdongnan and the Yinggehai basins. Hydrocarbons sourced from the Qiongdongnan Basin have relatively low maturities, whereas hydrocarbons from the Yinggehai Basin have relatively higher maturities and seem to have been in association with hydrothermal fluids. The hydrothermal fluids from the Yinggehai Basin, in which methane, ethane, carbon dioxide, and especially aromatic hydrocarbons dissolved under the high-temperature and high-pressure subsurface conditions, migrated along the No. 1 fault and caused the abnormally high concentration of aromatic hydrocarbons, as well as the thermal anomalies in the gas field, especially near the No. 1 fault.

Hao, F.; Li, S.; Sun, Y. [China Univ. of Geosciences, Wuhan, Hubei (China). Dept. of Petroleum Geology; Zhang, Q. [Nanhai West Oil Corp., Guangdong (China). Inst. of Petroleum Exploration and Development

1998-07-01T23:59:59.000Z

436

CONE-DHT: A distributed self-stabilizing algorithm for a heterogeneous storage system  

E-Print Network [OSTI]

CONE-DHT: A distributed self-stabilizing algorithm for a heterogeneous storage system Sebastian of managing a dynamic heterogeneous storage system in a distributed way so that the amount of data assigned for a dynamic heterogeneous storage system. Many solutions for distributed storage systems have already been

Paderborn, Universität

437

Effective friction law for smallscale fault heterogeneity in 3D dynamic rupture  

E-Print Network [OSTI]

Effective friction law for smallscale fault heterogeneity in 3D dynamic rupture S. Latour,1 M friction, we numerically construct effective friction laws that integrate the effects of smallscale, the static friction heterogeneities and the friction law. We first define a periodic smallscale heterogeneous

Nicolas, Chamot-Rooke

438

Data-driven Techniques to Estimate Parameters in the Homogenized Energy Model for Shape Memory Alloys  

E-Print Network [OSTI]

, ferroelectric, and ferromagnetic materials. The energy origin of the model was originally investigated for SMA]. The original mod- els determined the equilibrium phase using the Gibbs energy to predict the mesoscopic (orData-driven Techniques to Estimate Parameters in the Homogenized Energy Model for Shape Memory

439

Enhanced HFIR overpower margin through improvements in fuel plate homogeneity inspection  

SciTech Connect (OSTI)

Fuel homogeneity inspection techniques used on the HFIR fuel plates have recently been improved through conversion of the X-ray inspection device to acquire, store, and process data digitally. This paper reports some early results from using the improved equipment and describes future plans for obtaining enhanced fuel thermal performance by exploiting this improved inspection capability.

Rothrock, R.B.; Hale, R.E.; Knight, R.W. [Oak Ridge National Lab., TN (United States); Cheverton, R.D.

1995-09-01T23:59:59.000Z

440

FIRSTORDER CORRECTOR FOR THE HOMOGENIZATION OF THE CRITICALITY EIGENVALUE PROBLEM IN THE EVEN PARITY  

E-Print Network [OSTI]

FIRST­ORDER CORRECTOR FOR THE HOMOGENIZATION OF THE CRITICALITY EIGENVALUE PROBLEM IN THE EVEN of the criticality eigenvalue problem for the even parity flux of neutron transport in a domain with isotropic to determine the power distribution of neutrons in nuclear reactors. In the case of a stable reactor, only

Bal, Guillaume

Note: This page contains sample records for the topic "homogeneous catalysis heterogeneous" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


441

The evolution of a spatially homogeneous and isotropic universe filled with a collisionless gas  

E-Print Network [OSTI]

We review the evolution of a spatially homogeneous and isotropic universe described by a Friedmann-Robertson-Walker spacetime filled with a collisionless, neutral, simple, massive gas. The gas is described by a one-particle distribution function which satisfies the Liouville equation and is assumed to be homogeneous and isotropic. Making use of the isometries of the spacetime, we define precisely the homogeneity and isotropicity property of the distribution function, and based on this definition we give a concise derivation of the most general family of such distribution functions. For this family, we construct the particle current density and the stress-energy tensor and consider the coupled Einstein-Liouville system of equations. We find that as long as the distribution function is collisionless, homogenous and isotropic, the evolution of a Friedmann-Robertson-Walker universe exhibits a singular origin. Its future development depends upon the curvature of the spatial sections: spatially flat or hyperboloid universes expand forever and this expansion dilutes the energy density and pressure of the gas, while a universe with compact spherical sections reaches a maximal expansion, after which it reverses its motion and recollapses to a final crunch singularity where the energy density and isotropic pressure diverge. Finally, we analyze the evolution of the universe filled with the collisionless gas once a cosmological constant is included.

Francisco Astorga; Olivier Sarbach; Thomas Zannias

2014-06-14T23:59:59.000Z

442

DOI: 10.1002/cssc.201000142 Homogeneous Oxidation Reactions of Propanediols at Low  

E-Print Network [OSTI]

are consistent with chain propagation processes mediated by oxygen-containing radicals. The high acrolein selectivity in homogeneous 1,3-propane- diol oxidation led us to introduce the acrolein and H2O formed acrolein into acrylic acid with 90% yields (based on propanediol reactants). This com- bined process

Iglesia, Enrique

443

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

444

Finite order polynomial moment solutions of the homogeneous Grad-Shafranov equation  

SciTech Connect (OSTI)

A method for generating the finite positive order polynomial moment solutions of the homogeneous Grad-Shafranov equation to arbitrary order and the explicit form of the first few moments are given. A criticism of the method is discussed, and several practical examples are given.

Reusch, M.F.; Neilson, G.H.

1984-02-01T23:59:59.000Z

445

Detailed Analysis and Control Issues of Homogeneous Charge Compression Ignition (HCCI)  

SciTech Connect (OSTI)

Homogeneous charge compression ignition (HCCI) is a new combustion technology that may develop as an alternative to diesel engines with high efficiency and low NOx and particulate matter emissions. This paper describes the HCCI research activities being currently pursued at Lawrence Livermore National Laboratory and at the University of California Berkeley. Current activities include analysis as well as experimental work.

Aceves, Salvador M.; Flowers, Daniel L.; Martinez-Frias, Joel; Espinosa-Loza, Francisco; Dibble, Robert

2002-08-25T23:59:59.000Z

446

Dynamics of Homogeneous Charge Compression Ignition (HCCI) Engines with High Dilution  

E-Print Network [OSTI]

Dynamics of Homogeneous Charge Compression Ignition (HCCI) Engines with High Dilution C. J. Chiang (HCCI) engines in light of the cycle-to-cycle thermal feedback due to the high percentage of exhaust temperature is the primary mechanism for con- trolling ignition timing in an HCCI engine, especially when

Stefanopoulou, Anna

447

Sensitivity Analysis of Combustion Timing and Duration of Homogeneous Charge Compression Ignition (HCCI) Engines  

E-Print Network [OSTI]

(HCCI) Engines C. J. Chiang and A. G. Stefanopoulou University of Michigan, Ann Arbor Email: cjchiang of a Homogeneous Charge Com- pression Ignition (HCCI) engine. Qualitative and quantitative information on the individual effects of fuel and exhaust gas recirculation (EGR) on the HCCI combustion is provided. Using

Stefanopoulou, Anna

448

Spatial homogenization of thermal feedback regions in Monte Carlo reactor calculations  

SciTech Connect (OSTI)

An integrated thermal-hydraulic feedback module has previously been developed for the Monte Carlo transport solver, MC21. The module incorporates a flexible input format that allows the user to describe heat transfer and coolant flow paths within the geometric model at any level of spatial detail desired. The effect that the varying levels of spatial homogenization of thermal regions has on the accuracy of the Monte Carlo simulations is examined in this study. Six thermal feedback mappings are constructed from the same geometric model of the Calvert Cliffs core. The spatial homogenization of the thermal regions is varied, giving each scheme a different level of detail, and the adequacy of the spatial homogenization is determined based on the eigenvalue produced by each Monte Carlo calculation. The purpose of these numerical experiments is to determine the level of detail necessarily to accurately capture the thermal feedback effect on reactivity. Several different core models are considered: axial-flow only, axial and lateral flow, asymmetry due to control rod insertion, and fuel heating (temperature -dependent cross sections). The thermal results generated by the MC21 thermal feedback module are consistent with expectations. Based upon the numerical experiments conducted it is concluded that the amount of spatial detail necessary to accurately capture the feedback effect on reactivity is relatively small. Homogenization at the assembly level for the Calvert Cliffs PWR model results in a similar power defect to that calculated with individual pin-cells modeled as explicit thermal regions. (authors)

Hanna, B. R.; Gill, D. F.; Griesheimer, D. P. [Bertis Atomic Power Laboratory, Bechtel Marine Propulsion Corporation, P.O. Box 79, West Mifflin, PA 15122 (United States)

2012-07-01T23:59:59.000Z

449

ASSESSING THE LIQUEFACTION RISK REDUCTION OF REINFORCED SOILS: A HOMOGENIZATION APPROACH  

E-Print Network [OSTI]

liquefaction risk reduction factor. Then section 4 develops the same evaluation for a cross trench reinforcedASSESSING THE LIQUEFACTION RISK REDUCTION OF REINFORCED SOILS: A HOMOGENIZATION APPROACH Maxime for the reduction of the liquefaction risk, which can be expected from reinforcing the soil by a periodic array

Paris-Sud XI, Université de

450

FAST AND ROBUST NUMERICAL SOLUTION OF THE RICHARDS EQUATION IN HOMOGENEOUS SOIL  

E-Print Network [OSTI]

kr(#(p))(#p - z) in case of a homogeneous soil. Here, p is the unknown water or capillary pressure on# Ã? (0, T ) for a time T > 0 and a domain# # R 3 inhibited by the porous medium. The porosity.e., these parameter functions are fixed on# and describe the relationships in a single soil only. Concrete forms

Kornhuber, Ralf

451

FAST AND ROBUST NUMERICAL SOLUTION OF THE RICHARDS EQUATION IN HOMOGENEOUS SOIL  

E-Print Network [OSTI]

) in case of a homogeneous soil. Here, p is the unknown water or capillary pressure on Ã? (0, T ) for a time T > 0 and a domain R3 inhibited by the porous medium. The porosity and the hydraulic conductivity the relationships in a single soil only. Concrete forms of these functions have been given by Brooks and Corey [13

Kornhuber, Ralf

452

ELECTRICAL IMPEDANCE MAMMOGRAPHY Forward problem for homogeneous and 3-D sphere  

E-Print Network [OSTI]

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

Cerveny, Vlastislav

453

Statistical fracture modeling: crack path and fracture criteria with application to homogeneous and  

E-Print Network [OSTI]

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

Ritchie, Robert

454

Homogeneous Decomposition Mechanisms of Diethylzinc by Raman Spectroscopy and Quantum Chemical Calculations  

E-Print Network [OSTI]

for direct reaction products in an inverted, impinging-jet test reactor coupled to a Raman spectrometer. The homogeneous thermal decomposition of DEZn in N2 carrier was followed in an impinging-jet, up-flow reactor vibrational frequencies of DEZn, as well as anticipated intermediates and products. Comparison of the measured

Anderson, Timothy J.

455

Single-Step Assembly of Homogenous Lipid Polymeric and Lipid Quantum  

E-Print Network [OSTI]

Single-Step Assembly of Homogenous Lipid Polymeric and Lipid Quantum Dot Nanoparticles Enabled shown that hybrid lipid polymeric NPs combine the desir- able characteristics of polymeric NPs by entrapping one agent in the lipid envelope and the other one in the polymeric core.5 The development of novel

Zhang, Liangfang

456

Projective re-normalization for improving the behavior of a homogeneous conic linear system  

E-Print Network [OSTI]

In this paper we study the homogeneous conic system F : Ax = 0, x ? C \\ {0}. We choose a point ¯s ? intC? that serves as a normalizer and consider computational properties of the normalized system F¯s : Ax = 0, ¯sT x = 1, ...

Belloni, Alexandre

457

Optimal Homogenization of Perfusion Flows in Microfluidic Bio-Reactors: A Numerical Study  

E-Print Network [OSTI]

Optimal Homogenization of Perfusion Flows in Microfluidic Bio-Reactors: A Numerical Study Fridolin of Denmark, DTU Nanotech, Kongens Lyngby, Denmark Abstract In recent years, the interest in small-scale bio-reactors microfluidic bio-reactors, we develop a general design of a continually feed bio- reactor with uniform

458

DRIVING FORCE FOR THE ELECTROMIGRATION OF AN IMPURITY IN A HOMOGENEOUS METAL  

E-Print Network [OSTI]

:01976003702015900 #12;160 electron impurity interaction, and (ii) to show that the electrostatic force vanishes159 DRIVING FORCE FOR THE ELECTROMIGRATION OF AN IMPURITY IN A HOMOGENEOUS METAL L. TURBAN (*), P as the flux of electric charge associated with a unit flux of the solute is shown to be equivalent

Boyer, Edmond

459

Microfluidic Assembly of Homogeneous and Janus Colloid-Filled Hydrogel Granules  

E-Print Network [OSTI]

Microfluidic Assembly of Homogeneous and Janus Colloid-Filled Hydrogel Granules Robert F. Shepherd 23234 ReceiVed March 21, 2006. In Final Form: August 15, 2006 The microfluidic assembly of colloid.11 A new route to granulation is suggested by the emergence of microfluidic techniques that allow

Lewis, Jennifer

460

Phenomenology for the decay of energy-containing eddies in homogeneous MHD turbulence  

E-Print Network [OSTI]

Phenomenology for the decay of energy-containing eddies in homogeneous MHD turbulence Murshed of simple, one-point phenomenological models for the decay of energy-containing eddies phenomenology has been previously verified against experiments in wind tunnels, and certain experimentally

Oughton, Sean

Note: This page contains sample records for the topic "homogeneous catalysis heterogeneous" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


461

Optimization of the structural Gabor functions in a homogeneous velocity model  

E-Print Network [OSTI]

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

Cerveny, Vlastislav

462

A Harmonic Approach for Calculating Daily Temperature Normals Constrained by2 Homogenized Monthly Temperature Normals3  

E-Print Network [OSTI]

1 1 A Harmonic Approach for Calculating Daily Temperature Normals Constrained by2 Homogenized a constrained harmonic technique that forces the daily30 temperature normals to be consistent with the monthly, or harmonic even though the annual march of temperatures for some locations can be highly asymmetric. Here, we

463

Preprint version -March 7, 2006 REITERATED HOMOGENIZATION OF A CAVITATION PROBLEM  

E-Print Network [OSTI]

Preprint version - March 7, 2006 REITERATED HOMOGENIZATION OF A CAVITATION PROBLEM IN THIN FILMS theory: cavitation phenomena and roughness of the surfaces in relative motion: cavitation is defined to describe the behavior of a viscous cavitated flow in the lubrication framework. However, in practical

Paris-Sud XI, Université de

464

Homogeneity of precipitation series in the Netherlands and their trends in the past century  

E-Print Network [OSTI]

1 Homogeneity of precipitation series in the Netherlands and their trends in the past century T. A. Buishand, G. De Martino, J.N. Spreeuw and T. Brandsma Royal Netherlands Meteorological Institute (KNMI), De Bilt, The Netherlands ABSTRACT: The historical daily precipitation observations for the Netherlands

Brandsma, Theo

465

Homogeneous Bottleneck Model of Matrix-assisted Ultraviolet Laser Desorption of  

E-Print Network [OSTI]

Akos Vertes", R. Gijbels Department of Chemistry, University of Antwerp (UIA), Universiteitsplein 1, B volatilization are examined in a simple model. The key material factors appear to be a low heat of sublimation to the sublimation induction period. The model is homogeneous in that the energy density is taken to be uniform

Vertes, Akos

466

Rate constants for the homogeneous gas-phase Al/HCl combustion chemistry  

E-Print Network [OSTI]

Rate constants for the homogeneous gas-phase Al/HCl combustion chemistry Mark T. Swiharta Engineering, University at Buffalo (SUNY), Buffalo, NY 14260-4200, USA b Laboratoire de Combustion et Syste Orleans cedex 2, France c Laboratoire de Combustion et Syste`mes Re´actifs (LCSR), CNRS, 1C, av. de la

Swihart, Mark T.

467

Coal Segregation Control for Meeting Homogeneity Z. Huang, R. Kumar J. Yingling, J. Sottile  

E-Print Network [OSTI]

Coal Segregation Control for Meeting Homogeneity Standards Z. Huang, R. Kumar J. Yingling, J were developed to control coal segre- gation to meet ash targets over large coal batches (e. g., a unit train of coal) while realizing high yields and economic savings. We have extended this work to address

Kumar, Ratnesh

468

Platinum-Based Electrocatalysts Synthesized by Depositing a Contiguous...  

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

inventive catalysts. Applications and Industries Supercapacitors, batteries, fuel cells; oxygen-reduction; heterogeneous catalysis Technology Status Technology ID Development...

469

Temperature-dependent structural heterogeneity in calcium silicate liquids.  

SciTech Connect (OSTI)

X-ray diffraction measurements performed on aerodynamically levitated CaSiO{sub 3} droplets have been interpreted using a structurally heterogeneous liquid-state model. When cooled, the high-temperature liquid shows evidence of the polymerization of edge shared Ca octahedra. Diffraction isosbestic points are used to characterize the polymerization process in the pair-distribution function. This behavior is linear in the high-temperature melt but exhibits rapid growth just above the glass transition temperature around 1.2T{sub g}. The heterogeneous liquid interpretation is supported by molecular-dynamics simulations which show the CaSiO{sub 3} glass has more edge-shared polyhedra and fewer corner shared polyhedra than the liquid model.

Benmore, C. J.; Weber, J. K. R.; Wilding, M. C.; Du, J.; Parise, J. B. (X-Ray Science Division); (Materials Development Inc.); (Aberystwyth Univ.); (State Univ. of New York at Stony Brook); (Univ. of North Texas)

2010-12-07T23:59:59.000Z

470

Mining Large Heterogeneous Graphs using Cray s Urika  

SciTech Connect (OSTI)

Pattern discovery and predictive modeling from seemingly related Big Data represented as massive, ad-hoc, heterogeneous networks (e.g., extremely large graphs with complex, possibly unknown structure) is an outstanding problem in many application domains. To address this problem, we are designing graph-mining algorithms capable of discovering relationship-patterns from such data and using those discovered patterns as features for classification and predictive modeling. Specifically, we are: (i) exploring statistical properties, mechanics and generative models of behavior patterns in heterogeneous information networks, (ii) developing novel, automated and scalable graph-pattern discovery algorithms and (iii) applying our relationship-analytics (data science + network science) expertise to domains spanning healthcare to homeland security.

Sukumar, Sreenivas R [ORNL] [ORNL; Bond, Nathaniel A [ORNL] [ORNL

2013-01-01T23:59:59.000Z

471

Dynamics of Coupled Maps in Heterogeneous Random Networks  

E-Print Network [OSTI]

We study expanding circle maps interacting in a heterogeneous random network. Heterogeneity means that some nodes in the network are massively connected, while the remaining nodes are only poorly connected. We provide a probabilistic approach which enables us to describe the effective dynamics of the massively connected nodes when taking a weak interaction limit. More precisely, we show that for almost every random network and almost all initial conditions the high dimensional network governing the dynamics of the massively connected nodes can be reduced to a few macroscopic equations. Such reduction is intimately related to the ergodic properties of the expanding maps. This reduction allows one to explore the coherent properties of the network.

Tiago Pereira; Sebastian van Strien; Jeroen S. W. Lamb

2013-08-26T23:59:59.000Z

472

Test applications for heterogeneous real-time network testbed  

SciTech Connect (OSTI)

This paper investigates several applications for a heterogeneous real-time network testbed. The network is heterogeneous in terms of network devices, technologies, protocols, and algorithms. The network is real-time in that its services can provide per-connection end-to-end performance guarantees. Although different parts of the network use different algorithms, all components have the necessary mechanisms to provide performance guarantees: admission control and priority scheduling. Three applications for this network are described in this paper: a video conferencing tool, a tool for combustion modeling using distributed computing, and an MPEG video archival system. Each has minimum performance requirements that must be provided by the network. By analyzing these applications, we provide insights to the traffic characteristics and performance requirements of practical real-time loads.

Mines, R.F.; Knightly, E.W.

1994-07-01T23:59:59.000Z

473

Assembling thefacebook: Using heterogeneity to understand online social network assembly  

E-Print Network [OSTI]

Online social networks represent a popular and highly diverse class of social media systems. Despite this variety, each of these systems undergoes a general process of online social network assembly, which represents the complicated and heterogeneous changes that transform newly born systems into mature platforms. However, little is known about this process. For example, how much of a network's assembly is driven by simple growth? How does a network's structure change as it matures? How does network structure vary with adoption rates and user heterogeneity, and do these properties play different roles at different points in the assembly? We investigate these and other questions using a unique dataset of online connections among the roughly one million users at the first 100 colleges admitted to Facebook, captured just 20 months after its launch. We first show that different vintages and adoption rates across this population of networks reveal temporal dynamics of the assembly process, and that assembly is onl...

Jacobs, Abigail Z; Ugander, Johan; Clauset, Aaron

2015-01-01T23:59:59.000Z

474

Heterogeneous Beliefs, Collateralization, and Transactions in General Equilibrium  

E-Print Network [OSTI]

of the requirements for the degree of DOCTOR OF PHILOSOPHY Approved by: Co-Chairs of Committee, Leonardo Auernheimer Rajiv Sarin Committee Members, Thomas R. Saving David A. Bessler Amy J. Glass Head of Department, Timothy Gronberg August 2011 Major Subject...: Economics iii ABSTRACT Heterogeneous Beliefs, Collateralization, and Transactions in General Equilibrium. (August 2011) Xu Hu, B.B.A., The University of Science and Technology of China Co{Chairs of Advisory Committee: Dr. Leonardo Auernheimer Dr. Rajiv...

Hu, Xu

2012-10-19T23:59:59.000Z

475

Development of general inflow performance relationships (IPR`s) for slanted and horizontal wells producing heterogeneous solution-gas drive reservoirs  

SciTech Connect (OSTI)

Since 1968, the Vogel equation has been used extensively and successfully for analyzing the inflow performance relationship (IPR) of flowing vertical wells producing by solution-gas drive. Oil well productivity can be rapidly estimated by using the Vogel IPR curve and well outflow performance. With recent interests on horizontal well technology, several empirical IPRs for solution-gas drive horizontal and slanted wells have been developed under homogeneous reservoir conditions. This report presents the development of IPRs for horizontal and slanted wells by using a special vertical/horizontal/slanted well reservoir simulator under six different reservoir and well parameters: ratio of vertical to horizontal permeability, wellbore eccentricity, stratification, perforated length, formation thickness, and heterogeneous permeability. The pressure and gas saturation distributions around the wellbore are examined. The fundamental physical behavior of inflow performance for horizontal wells is described.

Cheng, A.M.

1992-04-01T23:59:59.000Z

476

Heterogeneous composite bodies with isolated lenticular shaped cermet regions  

DOE Patents [OSTI]

A heterogeneous body having ceramic rich cermet regions in a more ductile metal matrix. The heterogeneous bodies are formed by thermal spray operations on metal substrates. The thermal spray operations apply heat to a cermet powder and project it onto a solid substrate. The cermet powder is composed of complex composite particles in which a complex ceramic-metallic core particle is coated with a matrix precursor. The cermet regions are generally comprised of complex ceramic-metallic composites that correspond approximately to the core particles. The cermet regions are approximately lenticular shaped with an average width that is at least approximately twice the average thickness. The cermet regions are imbedded within the matrix phase and generally isolated from one another. They have obverse and reverse surfaces. The matrix phase is formed from the matrix precursor coating on the core particles. The amount of heat applied during the formation of the heterogeneous body is controlled so that the core particles soften but do not become so fluid that they disperse throughout the matrix phase. The force of the impact on the surface of the substrate tends to flatten them. The flattened cermet regions tend to be approximately aligned with one another in the body.

Sherman, Andrew J. (Cirtland Hills, OH)

2009-12-22T23:59:59.000Z

477

IEEE TRANSACTIONS ON CONTROL SYSTEMS TECHNOLOGY, VOL. 15, NO. 2, MARCH 2007 209 Stability Analysis in Homogeneous Charge  

E-Print Network [OSTI]

in Homogeneous Charge Compression Ignition (HCCI) Engines With High Dilution Chia-Jui Chiang and Anna G of homogeneous charge compression ignition (HCCI) en- gines with exhaust dilution. We find conditions under which into account the internal feedback structure of the thermal dynamics. Specifically, HCCI combustion timing

Stefanopoulou, Anna

478

Generation of large-scale vorticity in a homogeneous turbulence with a mean velocity shear Tov Elperin,* Nathan Kleeorin,  

E-Print Network [OSTI]

Generation of large-scale vorticity in a homogeneous turbulence with a mean velocity shear Tov by the gradient of the Reynolds stresses is studied. Generation of a mean vorticity in a homogeneous-induced'' deflection of equilibrium mean vorticity and ``Reynolds stress-induced'' generation of perturbations of mean

Elperin, Tov

479

Critical Dynamics of Spontaneous Symmetry Breaking in a Homogeneous Bose gas  

E-Print Network [OSTI]

We explore the dynamics of spontaneous symmetry breaking in a homogeneous system by thermally quenching an atomic gas with short-range interactions through the Bose-Einstein phase transition. Using homodyne matter-wave interferometry to measure first-order correlation functions, we verify the central quantitative prediction of the Kibble-Zurek theory, namely the homogeneous-system power-law scaling of the coherence length with the quench rate. Moreover, we directly confirm its underlying hypothesis, the freezing of the correlation length near the transition due to critical slowing down. Our measurements agree with beyond mean-field theory, and support the previously unverified expectation that the dynamical critical exponent for this universality class, which includes the $\\lambda$-transition of liquid $^4$He, is $z=3/2$.

Nir Navon; Alexander L. Gaunt; Robert P. Smith; Zoran Hadzibabic

2014-10-30T23:59:59.000Z

480

Homogenization approach for the transmission eigenvalue problem for periodic media and application to the inverse problem  

E-Print Network [OSTI]

We consider the interior transmission problem associated with the scattering by an inhomogeneous (possibly anisotropic) highly oscillating periodic media. We show that, under appropriate assumptions, the solution of the interior transmission problem converges to the solution of a homogenized problem as the period goes to zero. Furthermore, we prove that the associated real transmission eigenvalues converge to transmission eigenvalues of the homogenized problem. Finally we show how to use the first transmission eigenvalue of the period media, which is measurable from the scattering data, to obtain information about constant effective material properties of the periodic media. The convergence results presented here are not optimal. Such results with rate of convergence involve the analysis of the boundary correction and will be subject of a forthcoming paper.

Fioralba Cakoni; Houssem Haddar; Isaac Harris

2014-10-14T23:59:59.000Z

Note: This page contains sample records for the topic "homogeneous catalysis heterogeneous" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


481

Homogeneous spectroscopic parameters for bright planet host stars from the northern hemisphere  

E-Print Network [OSTI]

Aims. In this work we derive new precise and homogeneous parameters for 37 stars with planets. For this purpose, we analyze high resolution spectra obtained by the NARVAL spectrograph for a sample composed of bright planet host stars in the northern hemisphere. The new parameters are included in the SWEET-Cat online catalogue. Methods. To ensure that the catalogue is homogeneous, we use our standard spectroscopic analysis procedure, ARES+MOOG, to derive effective temperatures, surface gravities, and metallicities. These spectroscopic stellar parameters are then used as input to compute the stellar mass and radius, which are fundamental for the derivation of the planetary mass and radius. Results. We show that the spectroscopic parameters, masses, and radii are generally in good agreement with the values available in online databases of exoplanets. There are some exceptions, especially for the evolved stars. These are analyzed in detail focusing on the effect of the stellar mass on the derived planetary mass. ...

Sousa, S G; Mortier, A; Tsantaki, M; Adibekyan, V; Mena, E Delgado; Israelian, G; Rojas-Ayala, B; Neves, V

2015-01-01T23:59:59.000Z

482

Analytical formulation of 3D dynamic homogenization for periodic elastic systems  

E-Print Network [OSTI]

Homogenization of the equations of motion for a three dimensional periodic elastic system is considered. Expressions are obtained for the fully dynamic effective material parameters governing the spatially averaged fields by using the plane wave expansion (PWE) method. The effective equations are of Willis form (Willis 1997) with coupling between momentum and stress and tensorial inertia. The formulation demonstrates that the Willis equations of elastodynamics are closed under homogenization. The effective material parameters are obtained for arbitrary frequency and wavenumber combinations, including but not restricted to Bloch wave branches for wave propagation in the periodic medium. Numerical examples for a 1D system illustrate the frequency dependence of the parameters on Bloch wave branches and provide a comparison with an alternative dynamic effective medium theory (Shuvalov 2011) which also reduces to Willis form but with different effective moduli.

A. N. Norris; A. L. Shuvalov; A. A. Kutsenko

2012-01-13T23:59:59.000Z

483

On the energy-momentum spectrum of a homogeneous Fermi gas  

E-Print Network [OSTI]

We consider translation invariant quantum systems in thermodynamic limit. We argue that their energy-momentum spectra should have shapes consistent with effective models involving quasiparticles. Our main example is second quantized homogeneous interacting Fermi gas in a large cubic box with periodic boundary conditions, at zero temperature. We expect that its energy-momentum spectrum has a positive energy gap and a positive critical velocity.

Jan Derezi?ski; Krzysztof A. Meissner; Marcin Napiórkowski

2012-06-01T23:59:59.000Z

484

Non-homogeneous solutions of a Coulomb Schrödinger equation as basis set for scattering problems  

SciTech Connect (OSTI)

We introduce and study two-body Quasi Sturmian functions which are proposed as basis functions for applications in three-body scattering problems. They are solutions of a two-body non-homogeneous Schrödinger equation. We present different analytic expressions, including asymptotic behaviors, for the pure Coulomb potential with a driven term involving either Slater-type or Laguerre-type orbitals. The efficiency of Quasi Sturmian functions as basis set is numerically illustrated through a two-body scattering problem.

Del Punta, J. A.; Ambrosio, M. J.; Gasaneo, G. [Departamento de Física, Universidad Nacional del Sur, 8000 Bahía Blanca, Buenos Aires (Argentina)] [Departamento de Física, Universidad Nacional del Sur, 8000 Bahía Blanca, Buenos Aires (Argentina); Zaytsev, S. A. [Physics Department, Pacific National University, Khabarovsk 680035 (Russian Federation)] [Physics Department, Pacific National University, Khabarovsk 680035 (Russian Federation); Ancarani, L. U. [Théorie, Modélisation, Simulation, SRSMC, UMR CNRS 7565, Université de Lorraine, 57078 Metz (France)] [Théorie, Modélisation, Simulation, SRSMC, UMR CNRS 7565, Université de Lorraine, 57078 Metz (France)

2014-05-15T23:59:59.000Z

485

3D periodic dielectric composite homogenization based on the Generalized Source Method  

E-Print Network [OSTI]

The article encloses a new Fourier space method for rigorous optical simulation of 3D periodic dielectric structures. The method relies upon rigorous solution of Maxwell's equations in complex composite structures by the Generalized Source Method. Extremely fast GPU enabled calculations provide a possibility for an efficient search of eigenmodes in 3D periodic complex structures on the basis of rigorously obtained resonant electromagnetic response. The method is applied to the homogenization problem demonstrating a complete anisotropic dielectric tensor retrieval.

Shcherbakov, Alexey A

2015-01-01T23:59:59.000Z

486

Energy and Momentum in Spacetime Homogeneous G$\\ddot{o}$del-type Metrics  

E-Print Network [OSTI]

Using Einstein and Papapetrou energy-momentum complexes, we explicitly calculate the energy and momentum distribution associated with spacetime homogeneous G$\\ddot{o}$del-type metrics. We obtain that the two definitions of energy-momentum complexes do not provide the same result for these type of metrics. However, it is shown that the results obtained are reduced to the energy-momentum densities of G$\\ddot{o}$del metric already available in the literature

M. Sharif

2003-10-03T23:59:59.000Z

487

Comparison of Different Upscaling Methods for Predicting Thermal Conductivity of Complex Heterogeneous Materials System: Application on Nuclear Waste Forms  

SciTech Connect (OSTI)

To develop a strategy in thermal conductivity prediction of a complex heterogeneous materials system, loaded nuclear waste forms, the computational efficiency and accuracy of different upscaling methods have been evaluated. The effective thermal conductivity, obtained from microstructure information and local thermal conductivity of different components, is critical in predicting the life and performance of waste form during storage. Several methods, including the Taylor model, Sachs model, self-consistent model, and statistical upscaling method, were developed and implemented. Microstructure based finite element method (FEM) prediction results were used to as benchmark to determine the accuracy of the different upscaling methods. Micrographs from waste forms with varying waste loadings were used in the prediction of thermal conductivity in FEM and homogenization methods. Prediction results demonstrated that in term of efficiency, boundary models (e.g., Taylor model and Sachs model) are stronger than the self-consistent model, statistical upscaling method, and finite element method. However, when balancing computational efficiency and accuracy, statistical upscaling is a useful method in predicting effective thermal conductivity for nuclear waste forms.

Li, Dongsheng; Sun, Xin; Khaleel, Mohammad A.

2012-06-16T23:59:59.000Z

488

Status of axial heterogeneous liquid-metal fast breeder reactor core design studies and research and development  

SciTech Connect (OSTI)

The current status of axial heterogeneous core (AHC) design development in Japan, which consists of an AHC core design in a pool-type demonstration fast breeder reactor (DFBR) and research and development activities supporting AHC core design, is presented. The DFBR core design objectives developed by The Japan Atomic Power Company include (a) favorable core seismic response, (b) core compactness, (c) high availability, and (d) lower fuel cycle cost. The AHC concept was selected as a reference pool-type DFBR core because it met these objectives more suitably than the homogeneous core (HOC). The AHC core layouts were optimized emphasizing the reduction of the burnup reactivity swing, peak fast fluence, and power peaking. The key performance parameters resulting from the AHC, such as flat axial power/flux distribution, lower peak fast fluence, lower burnup reactivity swing, etc., were evaluated in comparison with the HOC. The critical experiments at the Japan Atomic Energy Research Institute's Fast Critical Assembly facility demonstrate the key AHC performance characteristics. The large AHC engineering benchmark experiments using the zero-power plutonium reactor and the AHC fuel pin irradiation test program using the JOYO reactor are also presented.

Nakagawa, H.; Inagaki, T.; Yoshimi, H.; Shirakata, K.; Watari, Y.; Suzuki, M.; Inoue, K.

1988-11-01T23:59:59.000Z

489

Final Technical Report - Investigation into the Relationship between Heterogeneity and Heavy-Tailed Solute Transport  

SciTech Connect (OSTI)

The objective of this project was to characterize the influence that naturally complex geologic media has on anomalous dispersion and to determine if the nature of dispersion can be estimated from the underlying heterogeneous media. The UNM portion of this project was to provide detailed representations of aquifer heterogeneity through producing highly-resolved models of outcrop analogs to aquifer materials. This project combined outcrop-scale heterogeneity characterization (conducted at the University of New Mexico), laboratory experiments (conducted at Sandia National Laboratory), and numerical simulations (conducted at Sandia National Laboratory and Colorado School of Mines). The study was designed to test whether established dispersion theory accurately predicts the behavior of solute transport through heterogeneous media and to investigate the relationship between heterogeneity and the parameters that populate these models. The dispersion theory tested by this work was based upon the fractional advection-dispersion equation (fADE) model. Unlike most dispersion studies that develop a solute transport model by fitting the solute transport breakthrough curve, this project explored the nature of the heterogeneous media to better understand the connection between the model parameters and the aquifer heterogeneity. We also evaluated methods for simulating the heterogeneity to see whether these approaches (e.g., geostatistical) could reasonably replicate realistic heterogeneity. The UNM portion of this study focused on capturing realistic geologic heterogeneity of aquifer analogs using advanced outcrop mapping methods.

Weissmann, Gary S

2013-12-06T23:59:59.000Z

490

Classifying spaces for homogeneous manifolds and their related Lie isometry deformations  

E-Print Network [OSTI]

Among plenty of applications, low-dimensional homogeneous spaces appear in cosmological models as both, classical factor spaces of multidimensional geometry and minisuperspaces in canonical quantization. Here a new tool to restrict their continuous deformations is presented: Classifying spaces for homogeneous manifolds and their related Lie isometry deformations. The adjoint representation of n-dimensional real Lie algebras induces a natural topology on their classifying space, which encodes the natural algebraic relationship between different Lie algebras therein. For n>1 this topology is not Hausdorffian. Even more it satisfies only the separation axiom T_0, but not T_1, i.e. there is a constant sequence which has a limit different from the members of the sequence. Such a limit is called a transition. Recently it was found that transitions are the natural generalization and transitive completion of the well-known In\\"on\\"u-Wigner contractions. For n<5 the relational classifying spaces are constructed explicitly. Calculating their characteristic scalar invariants via triad representations of the characteristic isometry, local homogeneous Riemannian 3-spaces are classified in their natural geometrical relations to each other. Their classifying space is a composition of pieces with different isometry types. Although it is Hausdorffian, different topological transitions to the same limit may induce locally non-Euclidean regions (e.g. at Bianchi tppes VII_0).

M. Rainer

1996-02-28T23:59:59.000Z

491

Dense Heterogeneous Continuum Model of Two-Phase Explosion Fields  

SciTech Connect (OSTI)

A heterogeneous continuum model is proposed to describe the dispersion of a dense Aluminum particle cloud in an explosion. Let {alpha}{sub 1} denote the volume fraction occupied by the gas and {alpha}{sub 2} the fraction occupied by the solid, satisfying the volume conservation relation: {alpha}{sub 1} + {alpha}{sub 2} = 1. When the particle phase occupies a non-negligible volume fraction (i.e., {alpha}{sub 2} > 0), additional terms, proportional to {alpha}{sub 2}, appear in the conservation laws for two-phase flows. These include: (i) a particle pressure (due to particle collisions), (ii) a corresponding sound speed (which produces real eigenvalues for the particle phase system), (iii) an Archimedes force induced on the particle phase (by the gas pressure gradient), and (iv) multi-particle drag effects (which enhance the momentum coupling between phases). These effects modify the accelerations and energy distributions in the phases; we call this the Dense Heterogeneous Continuum Model. A characteristics analysis of the Model equations indicates that the system is hyperbolic with real eigenvalues for the gas phase: {l_brace}v{sub 1}, v{sub 1} {+-} {alpha}{sub 1}{r_brace} and for the 'particle gas' phase: {l_brace}v{sub 2}, v{sub 2} {+-}{alpha}{sub 2}{r_brace} and the particles: {l_brace}v{sub 2}{r_brace}, where v{sub i} and {alpha}{sub i} denote the velocity vector and sound speed of phase i. These can be used to construct a high-order Godunov scheme to integrate the conservation laws of a dense heterogeneous continuum.

Kuhl, A L; Bell, J B

2010-04-07T23:59:59.000Z

492

A heterogeneous hierarchical architecture for real-time computing  

SciTech Connect (OSTI)

The need for high-speed data acquisition and control algorithms has prompted continued research in the area of multiprocessor systems and related programming techniques. The result presented here is a unique hardware and software architecture for high-speed real-time computer systems. The implementation of a prototype of this architecture has required the integration of architecture, operating systems and programming languages into a cohesive unit. This report describes a Heterogeneous Hierarchial Architecture for Real-Time (H{sup 2} ART) and system software for program loading and interprocessor communication.

Skroch, D.A.; Fornaro, R.J.

1988-12-01T23:59:59.000Z

493

A microrheological study of hydrogel kinetics and micro-heterogeneity  

E-Print Network [OSTI]

DOI 10.1140/epje/i2014-14044-y Regular Article Eur. Phys. J. E (2014) 37: 44 THE EUROPEAN PHYSICAL JOURNAL E A microrheological study of hydrogel kinetics and micro-heterogeneity Anders Aufderhorst-Roberts1,a, William J. Frith2, and Athene M. Donald... unique mechan- ical properties [5]. The range of available low-molecular-weight hydro- gelating systems has increased in recent years as their discovery has steadily relied more upon rational de- sign and less upon serendipity [6]. Hydrogelating sys- tems...

Aufderhorst-Roberts, Anders; Frith, William J.; Donald, Athene M.

2014-05-27T23:59:59.000Z

494

The generation of efficient supported (Heterogeneous) olefin metathesis catalysts  

SciTech Connect (OSTI)

Over the past decade, a new family of homogeneous metathesis catalysts has been developed that will tolerate most organic functionalities as well as water and air. These homogeneous catalysts are finding numerous applications in the pharmaceutical industry as well as in the production of functional polymers. In addition the catalysts are being used to convert seed oils into products that can substitute for those that are now made from petroleum products. Seed oils are unsaturated, contain double bonds, and are a ready source of linear hydrocarbon fragments that are specifically functionalized. To increase the number of applications in the area of biomaterial conversion to petrol chemicals, the activity and efficiency of the catalysts need to be as high as possible. The higher the efficiency of the catalysts, the lower the cost of the conversion and a larger number of practical applications become available. Active supported catalysts were prepared and tested in the conversion of seed oils and other important starting materials. The outcome of the work was successful and the technology has been transferred to a commercial operation to develop viable applications of the discovered systems. A biorefinery that converts seed oils is under construction in Indonesia. The catalysts developed in this study will be considered for the next generation of operations.

Grubbs, Robert H

2013-04-05T23:59:59.000Z

495

Embracing diversity : improving performance for parallel storage systems built with heterogeneous disks  

E-Print Network [OSTI]

Figure I.2: Parallel Storage System Architecture FigureHeterogeneous Parallel Storage Systems . . . . . B. Modeldisks on a multimedia storage system with random data

Bruno, Gregory DuVall

2008-01-01T23:59:59.000Z

496

The application of inelastic neutron scattering to the investigation of industrial heterogeneous catalysts.  

E-Print Network [OSTI]

??Vibrational spectroscopy has been used to probe the surface chemistry of two heterogeneous catalysts. This has principally involved the application of infrared (IR) spectroscopy and… (more)

Hamilton, Neil G.

2010-01-01T23:59:59.000Z

497

Fracture permeability and seismic wave scattering--Poroelastic linear-slip interface model for heterogeneous fractures  

E-Print Network [OSTI]

modeling of faults and fractures: Geophysics, 60, 1514-1526.Poroelastic modeling of fracture-seismic wave interaction:by a heterogeneous fracture: J. Acoust. Soc. Am. , 115,

Nakagawa, S.

2010-01-01T23:59:59.000Z

498

Prevalence estimation under heterogeneity in the example of bovine trypanosomosis in Uganda  

E-Print Network [OSTI]

Prevalence estimation under heterogeneity in the example of bovine trypanosomosis in Uganda Dankmar of bovine trypanosomosis in Mukono County, Uganda. Fifty farms (referred to as clusters), were sampled

Boehning, Dankmar

499

E-Print Network 3.0 - analyzing heterogeneous samples Sample...  

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

heterogeneities Abdulla M. Al-Qawasmeh Anthony A. Maciejewski Haonan Wang Jay Smith Howard Jay Siegel... Jerry Potter Springer Science+Business Media, LLC 2011...

500

acetylation p1-4intratumoral heterogeneity: Topics by E-print...  

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

Sciences Websites Summary: Sequential Consistency for Heterogeneous-Race-Free DEREK R. HOWER, BRADFORD M. BECKMANN, BENEDICT R: Sequential Consistency for Data-Race-Free (SC for...