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1

ISHHC XIII International Symposium on the Relations betweenHomogeneous and Heterogeneous Catalysis  

SciTech Connect

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

2

Argonne Chemical Sciences & Engineering - Catalysis & Energy...  

NLE Websites -- All DOE Office Websites (Extended Search)

Catalysis & Energy Conversion * Heterogeneous Catalysis * Homogeneous Catalysis * Fuel Cell Engineering * Hydrogen & Fuel Cell Materials * Ceramic Electrochemistry Catalysis &...

3

Plenary lecture 2: nanotechnology and heterogeneous catalysis  

Science Conference Proceedings (OSTI)

Catalysis is the process in which the rate of a chemical reaction is increased by means of a chemical substance known as a catalyst. Catalysts can be either heterogeneous or homogeneous, depending on whether a catalyst exists in the same phase as the ...

Karim H. Hassan

2009-02-01T23:59:59.000Z

4

Textured Metal Catalysts for Heterogeneous Catalysis ...  

Biomass and Biofuels Advanced Materials Textured Metal Catalysts for Heterogeneous Catalysis Pacific Northwest National Laboratory. Contact ...

5

Molecular ingredients of heterogeneous catalysis  

Science Conference Proceedings (OSTI)

The purpose of this paper is to present a review and status report to those in theoretical chemistry of the rapidly developing surface science of heterogeneous catalysis. The art of catalysis is developing into science. This profound change provides one with opportunities not only to understand the molecular ingredients of important catalytic systems but also to develop new and improved catalyst. The participation of theorists to find answers to important questions is sorely needed for the sound development of the field. It is the authors hope that some of the outstanding problems of heterogeneous catalysis that are identified in this paper will be investigated. For this purpose the paper is divided into several sections. The brief Introduction to the methodology and recent results of the surface science of heterogeneous catalysis is followed by a review of the concepts of heterogeneous catalysis. Then, the experimental results that identified the three molecular ingredients of catalysis, structure, carbonaceous deposit and the oxidation state of surface atoms are described. Each section is closed with a summary and a list of problems that require theoretical and experimental scrutiny. Finally attempts to build new catalyst systems and the theoretical and experimental problems that appeared in the course of this research are described.

Somorjai, G.A.

1982-06-01T23:59:59.000Z

6

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

Science Conference Proceedings (OSTI)

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

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

2011-11-23T23:59:59.000Z

7

Surface science and heterogeneous catalysis  

DOE Green Energy (OSTI)

The catalytic reactions studied include hydrocarbon conversion over platinum, the transition metal-catalyzed hydrogenation of carbon monoxide, and the photocatalyzed dissociation of water over oxide surfaces. The method of combined surface science and catalytic studies is similar to those used in synthetic organic chemistry. The single-crystal models for the working catalyst are compared with real catalysts by comparing the rates of cyclopropane ring opening on platinum and the hydrogenation of carbon monoxide on rhodium single crystal surface with those on practical commercial catalyst systems. Excellent agreement was obtained for these reactions. This document reviews what was learned about heterogeneous catalysis from these surface science approaches over the past 15 years and present models of the active catalyst surface.

Somorjai, G.A.

1980-05-01T23:59:59.000Z

8

Heterogenization of Homogeneous Catalysts: the Effect of the Support  

DOE Green Energy (OSTI)

We have studied the influence of placing a soluble, homogeneous catalyst onto a solid support. We determined that such a 'heterogenized' homogeneous catalyst can have improved activity and selectivity for the asymmetric hydrogenation of enamides to amino acid derivatives. The route of heterogenization of RhDuPhos(COD){sup +} cations occurs via electrostatic interactions with anions that are capable of strong hydrogen bonding to silica surfaces. This is a novel approach to supported catalysis. Supported RhDuPhos(COD){sup +} is a recyclable, non-leaching catalyst in non-polar media. This is one of the few heterogenized catalysts that exhibits improved catalytic performance as compared to its homogeneous analog.

Earl, W.L.; Ott, K.C.; Hall, K.A.; de Rege, F.M.; Morita, D.K.; Tumas, W.; Brown, G.H.; Broene, R.D.

1999-06-29T23:59:59.000Z

9

Molecular-Level Design of Heterogeneous Chiral Catalysis  

SciTech Connect

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

10

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 principles in homogeneous catalysis. However, while homopolymers have been reported that have excellent thermal and phase-dependent solubility, less is known about copolymers. Also, less is known about the phase selective solubility of polar aprotic N,N-dialkyl polyacrylamides. This work describes a library synthesis of dye-labeled poly(N-n-octadecylacrylamide-co-N-n-butylacrylamide) copolymers and study of the effects of polymer composition in phase selective solubility of these copolymers. To study the relative importance of n-octadecyl versus n-butyl groups, copolymers with different ratios of n-octadecylacrylamide and n-butylacrylamide but with similar degrees of polymerization and polydispersity were prepared by a split-pool synthesis using a highly soluble poly(N-acryloxy-2-dodecylsuccinimide) as the precursor. Polymer sequestrants were used to remove excess amines and the byproduct N-hydroxyl-2- dodecylsuccinimide without fractionation of the polyacrylamides. Results demonstrated that poly(N-n-octadecylacrylamide-co-N-n-butylacrylamide) copolymers’ phase selective solubility is equally dependant of the polar n-butyl and nonpolar n-octadecyl groups on the copolymers. Dye-labeled poly(N,N-dialkylacrylamide)s prepared by the polymerization of N,N-dialkylacrylamides monomers with methyl, ethyl, propyl, butyl, hexyl, and dodecyl N-alkyl groups in a variety of thermomorphic or latent biphasic polar/nonpolar solvent mixtures were also prepared. Studies showed that poly(N,N-dialkylacrylamide)s have phase selective solubility that is highly dependent of the size of the N-alkyl group. Soluble polymers are known to be useful supports for catalysts. This thesis also describes approaches to immobilization of a variety of catalysts on polyisobutylene (PIB). The most effective of these catalysts were analogs of pyridyl N-oxides that have been used as organocatalysts for the catalytic allylation of a variety of aromatic aldehydes. PIB-supported N-oxide promoted the allylation of aldehydes in up to 99% isolated yield. The products were isolated in the polar phase of a thermomorphic system and the catalyst was recycled through five cycles.

Ortiz-Acosta, Denisse

2007-12-01T23:59:59.000Z

11

Pin diameter optimization in 1200 MWe heterogeneous vs. homogeneous LMFBRs  

SciTech Connect

LMFBRs with internal blankets (heterogeneous reactors) are known for reducing the sodium void reactivity and increasing the breeding ratio. As for homogeneous reactors, the optimization of the fuel pin diameter for heterogeneous reactors is of great interest. The optimum pin diameter is obtained by changing the fuel pin diameter until the homogenized fuel volume fraction is the same as the optimum fuel volume fraction of the homogeneous core. The optimization of the fuel pin diameter with respect to doubling time for a loosely coupled 1200 MWe oxide heterogeneous reactor is described. The results are compared with those of a homogeneous reactor.

Orechwa, Y.; Turski, R.B.; King, M.J.

1977-01-01T23:59:59.000Z

12

Molecular surface science of heterogeneous catalysis. History and perspective  

DOE Green Energy (OSTI)

A personal account is given of how the author became involved with modern surface science and how it was employed for studies of the chemistry of surfaces and heterogeneous catalysis. New techniques were developed for studying the properties of the surface monolayers: Auger electron spectroscopy, LEED, XPS, molecular beam surface scattering, etc. An apparatus was developed and used to study hydrocarbon conversion reactions on Pt, CO hydrogenation on Rh and Fe, and NH/sub 3/ synthesis on Fe. A model has been developed for the working Pt reforming catalyst. The three molecular ingredients that control catalytic properties are atomic surface structure, an active carbonaceous deposit, and the proper oxidation state of surface atoms. 40 references, 21 figures. (DLC)

Somorjai, G.A.

1983-08-01T23:59:59.000Z

13

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

14

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

Recanati, Catherine

15

Homogeneous and heterogeneous breast phantoms for UWB imaging  

Science Conference Proceedings (OSTI)

This paper presents the fabrication of homogeneous and heterogeneous breast phantoms for experimental breast cancer detection use. The phantoms were developed for UWB imaging technique. The fabrication materials were affordable and the process was minimal. ... Keywords: breast phantom for UWB imaging, breast tissues dielectric property, early breast cancer detection

Saleh Alshehri; Sabira Khatun; Zaiki Awang

2011-10-01T23:59:59.000Z

16

Cryogenic Homogenization and Sampling of Heterogeneous Multi-Phase Feedstock  

DOE Patents (OSTI)

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

Doyle, Glenn M.; Ideker, Virgene D.; Siegwarth, James D.

1999-09-21T23:59:59.000Z

17

High pressure heterogeneous catalysis in a low pressure UHV environment  

SciTech Connect

The major thrust of our research is to carry out for the first time a heterogeneous catalytic reaction that normally is observed only at high pressures (>1 atm) of reactant gas at low pressures (<10{sup {minus}4} Torr) in an ultrahigh vacuum environment. The reaction we have chosen is the steam reforming of methane on a Ni(111) crystal.

Ceyer, S.T.

1990-01-01T23:59:59.000Z

18

Catalysis  

Science Conference Proceedings (OSTI)

Catalysis presents the physicist with an excellent opportunity to contribute to the technology of energy supply by doing basic research. Recent developments in the experimental techniques for the preparation and investigation of solid surfaces and adsorbates and in the electronic theory of surfaces and of chemisorption quite naturally will provide insights into the fundamental processes of catalysis that were not accessible before and hold the promise of making catalysis an exact science in the foreseeable future. Such knowledge can be expected to promote in a significant way the discovery of new catalysts that will be necessary in the technology of energy production. An analysis of our natural resources reveals that for the next 50 years the major part of our energy supply will have to be provided by fossil fuels. The depletion of oil reserves makes it necessary to transform coal

T. E. Fischer

1974-01-01T23:59:59.000Z

19

Charge Transfer and Support Effects in Heterogeneous Catalysis  

SciTech Connect

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

20

DOE Laboratory Catalysis Research Symposium - Abstracts  

SciTech Connect

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

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

Mechanistic Studies at the Interface Between Organometallic Chemistry and Homogeneous Catalysis  

SciTech Connect

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

22

Study of Mercury Transformation with Chlorinated Species under Homogeneous and Heterogeneous Conditions.  

E-Print Network (OSTI)

??Mercury (Hg) transformation under homogeneous (gas-phase oxidation reactions primarily involving chlorine species in flue gases) and heterogeneous (gas-surface oxidation reactions involving surface enhanced Hg oxidation… (more)

Busireddy, Bhargavi

2009-01-01T23:59:59.000Z

23

Metal-surface reaction energetics. Theory and application to heterogeneous catalysis, chemisorption, and surface diffusion  

SciTech Connect

The title is esoteric. The subtitle is specialized. This is an edited book containing five chapters written by eight authors. It is not a book to read from beginning to end, but kept perusing this handsomely printed and well-edited volume, learned so much that he wishes to convey his message to a small but very successful group of chemists and chemical engineers in heterogeneous catalysis: there is a lot to learn in this book, not so much in theory but in the facts that the theorists who wrote the book are trying to explain today with the faint hope that tomorrow they will actually predict new chemistry in as yet unknown catalytic cycles.

Shustorovich, E. (ed.)

1991-01-01T23:59:59.000Z

24

Homogenization of a degenerate parabolic problem in a highly heterogeneous medium with highly anisotropic fibers  

Science Conference Proceedings (OSTI)

We consider the homogenization of a heat transfer problem in a periodic medium, consisting of a set of highly anisotropic fibers surrounded by insulating layers, the whole being embedded in a third material having a conductivity of order 1. The conductivity ... Keywords: Degenerate parabolic problem, Highly anisotropic fibers, Highly heterogeneous medium, Homogenization

Ahmed Boughammoura

2009-01-01T23:59:59.000Z

25

Catalysis | U.S. DOE Office of Science (SC)  

Office of Science (SC) Website

Catalysis Catalysis Basic Energy Sciences Advisory Committee (BESAC) BESAC Home Meetings Meeting Presentations History Logistics Members Charges/Reports Charter .pdf file (41KB) BES Committees of Visitors BES Home Meetings Catalysis Print Text Size: A A A RSS Feeds FeedbackShare Page Tuesday, May 14, 2002 - Opening Plenary Session Catalysis and Nanoscience Activities in BES - William Millman Energy Generation, Carbon Mgmt., and Methodology - John Frost Nanoscience and Catalysis - D. Wayne Goodman Wednesday, May 15, 2002 - 2nd Day Plenary Session Heterogeneous Catalysis - J. K. Norskov Homogeneous and Single-Site Heterogeneous Catalysis - Tobin Marks Thursday, May 16, 2002 - Breakout Summary Reports Catalysts Design Driven by Fundamental Research - Barteau Linking Basic Research to Applications - Bare Bell

26

Homogenization for Periodic Heterogeneous Materials with Arbitrary Position-Dependent Material Properties  

SciTech Connect

We present a rigorous homogenization approach for efficient computation of a class of physical problems in a one-dimensional periodic heterogeneous material. This material is represented by a spatially periodic array of unit cells with a length of e. More specifically, the method is applied to the diffusion, heat conduction, and wave propagation problems. Heterogeneous materials can have arbitrary position-dependent continuous or discontinuous materials properties (for example heat conductivity) within the unit cell. The final effective model includes both effective properties at the leading order and high-order contributions due to the microscopic heterogeneity. A dimensionless heterogeneity parameter ß is defined to represent high-order contributions, shown to be in the range of [-1/12, 0], and has a universal expression for all three problems. Both effective properties and heterogeneity parameter ß are independent of e, the microscopic scale of heterogeneity. The homogenized solution describing macroscopic variations can be obtained from the effective model. Solution with sub-unit-cell accuracy can be constructed based on the homogenized solution and its spatial derivatives. The paper represents a general approach to obtain the effective model for arbitrary periodic heterogeneous materials with position-dependent properties.

Xu Zhi-Jie

2012-08-01T23:59:59.000Z

27

Homogenization and Upscaling for Diffusion, Heat Conduction, and Wave Propagation in Heterogeneous Materials  

SciTech Connect

We present a general homogenization method for diffusion, heat conduction, and wave propagation in a periodic heterogeneous material with piecewise constants. The method is relevant to the frequently encountered upscaling issues for heterogeneous materials. The dispersion relation for each problem is first expressed in the general form where the frequency w (or wavenumber k) is expanded in terms of the wavenumber k (or frequency w). A general homogenization model can be directly obtained with any given dispersion relation. Next step we study the unit cell of the heterogeneous material and derive the exact dispersion relation. The final homogenized equations include both leading order terms (effective properties) and high order contributions that represent the effect of the microscopic heterogeneity on the macroscopic behavior. That effect can be lumped into a single dimensionless heterogeneity parameter, which is bounded between -1/12 less than or equal to less than or equal to 0 and has a universal expression for all three problems. Numerical examples validate the proposed method and demonstrate a significant computational saving.

Zhi-Jie Xu

2012-03-01T23:59:59.000Z

28

Surface functionalization of metal?organic polyhedron for homogeneous cyclopropanation catalysis  

Science Conference Proceedings (OSTI)

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

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

2012-03-13T23:59:59.000Z

29

Investigation on application of homogeneous and heterogeneous catalysis for alkaline waste treatment  

SciTech Connect

The stabilization of neptunium(IV) in alkaline solution by chemical reductants under various conditions was studied. Testing showed that neptunium(V) is slowly reduced to Np(IV) by V(IV) at room temperature in alkaline solutions. Increasing temperature accelerates reduction. Complete reduction of 2 x 10{sup -4} M Np(V) occurs in three hours at 80{degrees}C in 1 M NaOH with 0.02 M VOSO{sub 4-}. Under similar conditions, but in 5 M NaOH, only 15 to 20% of the Np(V) was reduced in 5 hours. In all cases, about 98 % of the initial neptunium was found in the precipitate. Thus V(IV) acts both as a reductant and as a precipitation carrier. Tests showed Np(V) reduction by hydrazine hydrate could be catalyzed by Pd(II). Reduction increased with temperature and catalyst concentration and decreased with hydroxide concentration. Reduction of Np(V) also takes place in 1 M NaOH solutions containing 1 M sodium formate and palladium. Increasing temperature accelerates reduction; with three hours` treatment in 5 M NaOH solution at 90{degrees}C, about 95 % of the initial 2 x 10{sup -4} M neptunium(V) is transformed to Np(IV). Organic complexants and organic acid anions hinder the decontamination of alkaline solutions from neptunium and plutonium by coprecipitation with d-element hydroxides (the Method of Appearing Reagents). It was found that ethylenediaminetetraacetate (EDTA) and N-(2-hydroxyethyl) ethylenediaminetriacetate (HEDTA) are decomposed by H{sub 2}O{sub 2} in alkaline solution in the presence of cobalt compounds with heating and by Na2S208 at moderate temperatures. Citrate, glycolate, and oxalate are decomposed by Na{sub 2}S{sub 2}O{sub 8} with heating. Oxidant amounts must be increased when NaNO{sub 2} also is present in solution. 8 refs., 25 figs., 16 tabs.

Shilov, V.P.; Bessonov, A.A.; Garnov, A.Y.; Gelis, A.V. [Russian Academy of Sciences, Moscow (Russian Federation). Institute of Physical Chemistry] [and others

1997-09-01T23:59:59.000Z

30

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

E-Print Network (OSTI)

or sulfated zirconia (MOx) a?ords propene and supportedium(III) catalysts, (allyl) 2 Ir-O-MOx. These catalysts were

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)

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

Somorjai Ed., G.A.

2007-01-01T23:59:59.000Z

32

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

33

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

E-Print Network (OSTI)

size e?ect in the Fischer-Tropsch synthesis. ” Stud. Surf.E. Rytter, A. Holmen ”Fischer-Tropsch synthesis over ?-Al 2Rytter, A. Holmen ”Fischer-Tropsch synthesis on Co supported

Somorjai Ed., G.A.

2007-01-01T23:59:59.000Z

34

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

E-Print Network (OSTI)

04, France Institut f¨ r Chemie, Freie Universit¨ t Berlin,Angewandte und Physikalische Chemie, Universit¨ t Bremen, uKuebel, R. Richards Angew. Chemie Int. Ed. , 45 (2006) 7277;

Somorjai Ed., G.A.

2007-01-01T23:59:59.000Z

35

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

E-Print Network (OSTI)

P. D. Yang, Angewandte Chemie-International Edition 2006,G. M. Schwab, Angewandte Chemie-International Edition 1967,

Somorjai, Gabor A.

2008-01-01T23:59:59.000Z

36

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

37

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

SciTech Connect

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

38

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

SciTech Connect

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

39

Cluster reactions: An approach to understanding the fundamentals of heterogeneous catalysis  

DOE Green Energy (OSTI)

The physical basis for catalysis is not well understood and the motivation for this ongoing research is to provide a basis for unraveling the role which composition, morphology and electronic states have on the functioning of catalysts for various classes of reactions. The work during the first two and one-half year grant period has focused on unsupported clusters of selected composition, charge state, and size. Research has proceeded along three general lines of inquiry: (1) investigation of the reactivity of these cluster materials and determination of the influence of their charged state; (2) determination of the kinetics of association (adsorption) of various reactants and unraveling the mechanisms of certain oxidation reactions known to be catalyzed on metal cluster alloys, oxides and carbides, and (3) thermochemical measurement of the absorption of gaseous species onto alloy and metal oxide and carbide cluster systems. The authors have pursued the role of metal and metal-oxide clusters, and the charge states of these, as they function to influence the reactions of adsorbed species including ammonia, alcohols, water, NO{sub x}, as well as CO and hydrogen. Evidence has been obtained that small positively charged nickel clusters function to catalyze reactions between adsorbed CO and hydrogen. In supportive studies, they have investigated the clustering of ammonia, methanol and water to nickel clusters of varying size. These studies, in conjunction with density functional calculations which are in progress, provide insight into cluster structures and knowledge of adsorption energies.

Castleman, A.W. Jr.

1994-11-01T23:59:59.000Z

40

High pressure heterogeneous catalysis in a low pressure ultrahigh vacuum environment  

DOE Green Energy (OSTI)

An apparatus was been developed which couples high resolution electron energy loss spectroscopy with molecular beam and scattering techniques. Exposure of Ni(111) to atomic H results in H embedded within the Ni lattice and a monolayer of H adsorbed on the surface. This surface-bound H was removed by an Xe atom beam. Subsequent exposure to CH[sub 4] results in dissociative adsorption, producing adsorbed CH[sub 3] and adsorbed H. Results documents a new mechanism for a surface reaction, a reaction between an adsorbed and a bulk species, and demonstrates the importance of bulk H as a reactant in a heterogeneous catalytic reaction.

Ceyer, S.T.

1992-01-01T23:59:59.000Z

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.


41

Argonne Chemical Sciences & Engineering - Catalysis & Energy...  

NLE Websites -- All DOE Office Websites (Extended Search)

News & Highlights Events Search Argonne ... Search Argonne Home > Chemical Sciences & Engineering > Homogeneous Catalysis * Members * Contact * Publications * Research Projects...

42

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

DOE Green Energy (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

43

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

44

HETEROGENEOUS CATALYSIS RESEARCH MEETING  

E-Print Network (OSTI)

costs for the production of SNG or Fischer-Tropsch productsof substitute natural gas (SNG) are highly susceptible to

Authors, Various

2011-01-01T23:59:59.000Z

45

HETEROGENEOUS CATALYSIS RESEARCH MEETING  

E-Print Network (OSTI)

production of SNG or Fischer-Tropsch products Therefore, abe trying to obtain from Fischer-Tropsch synthesis? Answer:intermediates in Fischer-Tropsch synthesis? Answer: It was

Authors, Various

2011-01-01T23:59:59.000Z

46

Homogeneous Nucleation of Water Anomalies Explained by Recognition and Elimination of Heterogeneous Species  

Science Conference Proceedings (OSTI)

A piston-typo expansion cloud chamber, capable of producing short pulses of nucleation, was used to study the homogeneous nucleation of water over a wide range of temperature and supersaturation. A large effort was made to remove impurities ...

Donald E. Hagen; James L. Kassner Jr.; Ronald C. Miller

1982-05-01T23:59:59.000Z

47

Parallel morphological/neural processing of hyperspectral images using heterogeneous and homogeneous platforms  

Science Conference Proceedings (OSTI)

The wealth spatial and spectral information available from last-generation Earth observation instruments has introduced extremely high computational requirements in many applications. Most currently available parallel techniques treat remotely sensed ... Keywords: Heterogeneous computing, Hyperspectral imaging, Mathematical morphology, Neural networks, Parallel performance

Javier Plaza; Rosa Pérez; Antonio Plaza; Pablo Martínez; David Valencia

2008-03-01T23:59:59.000Z

48

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

49

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

50

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

NLE Websites -- All DOE Office Websites (Extended Search)

Catalysis Tuesday, July 19, 2011 - 4:38pm SSRL Conference Room 137-322 Jeroen A. van Bokhoven, Professor for Heterogeneous Catalysis Institute for Chemical and Bioengineering ETH...

51

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

Science Conference Proceedings (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

52

Argonne Chemical Sciences & Engineering - People - Catalysis and Energy  

NLE Websites -- All DOE Office Websites (Extended Search)

Management and Support Management and Support Heterogeneous Catalysis Homogeneous Catalysis Fuel Cell Engineering Hydrogen and Fuel Cell Materials Ceramic Electrochemistry Electrochemical Projects Support Management and Support Theodore R. Krause, Chemical Engineer and Department Manager phone: 630/252-4356, fax: 630/972-4463, e-mail: krauset@anl.gov PhD, Chemical Engineering, University of Delaware Catalyst formulations and characterization Reaction kinetics Catalyst fundamentals Hydrogen production technologies Laurie A. Carbaugh, Administrative Secretary phone: 630/252-7556, fax: 630/252-9917, e-mail: laurie.carbaugh@anl.gov Romesh Kumar, Senior Chemical Engineer phone: 630/252-4342, fax: 630/252-4176, e-mail: kumar@anl.gov PhD, Chemical Engineering, University of California, Berkeley

53

Catalysis Workshop  

NLE Websites -- All DOE Office Websites (Extended Search)

Opportunities in Catalysis Research Using Synchrotron Radiation Opportunities in Catalysis Research Using Synchrotron Radiation Stanford Synchrotron Radiation Laboratory October 8-9, 2002 Organizer: Anders Nilsson Chemical catalysis is one of the research areas of enormous importance for the industrial society. There are important challenges to be met in the near future where development of new processes and catalysts are a necessity. We need to find a way to make methanol from methane, split water into hydrogen using sunlight, find replacement of platinum metals, etc. The fundamental understanding of many catalytic processes is still emerging and there seems to be a new opportunity with the recent development in experimental and theoretical methods. The intention of workshop was to bring researchers from many different disciplines together to discuss how synchrotron radiation can be applied to address some fundamental questions in catalysis.

54

Catalysis and Biocatalysis Technologies  

Science Conference Proceedings (OSTI)

ATP FOCUSED PROGRAM: Catalysis and Biocatalysis Technologies NOTE ... pharmaceuticals. And that only hints at the roles catalysis plays. ...

2011-10-19T23:59:59.000Z

55

CATALYSIS SCIENCE AND TECHNOLOGY  

Science Conference Proceedings (OSTI)

This is the final report of a three-year, Laboratory-Directed Research and Development (LDRD) project at the Los Alamos National Laboratory (LANL). Our objectives were to develop a multidisciplinary team and capabilities to develop a fundamental understanding of homogeneous, heterogeneous, and heterogenized catalysts. With the aid of theoretical chemistry approaches we explored and characterized the chemical reactivity and physical properties of a large number of catalytic systems.

M. ABRAMS; R. BAKER; ET AL

2000-08-01T23:59:59.000Z

56

2012 Catalysis Lectures  

NLE Websites -- All DOE Office Websites (Extended Search)

Catalysis Lectures May 21-24 2012 Bert Weckhuysen Bert Weckhuysen, who holds the chair of Inorganic Chemistry and Catalysis at Utrecht University, will give a series of catalysis...

57

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

Science Conference Proceedings (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

58

High pressure heterogeneous catalysis in a low pressure ultrahigh vacuum environment. Summary of progress report, July 1, 1989--December 31, 1992  

DOE Green Energy (OSTI)

An apparatus was been developed which couples high resolution electron energy loss spectroscopy with molecular beam and scattering techniques. Exposure of Ni(111) to atomic H results in H embedded within the Ni lattice and a monolayer of H adsorbed on the surface. This surface-bound H was removed by an Xe atom beam. Subsequent exposure to CH{sub 4} results in dissociative adsorption, producing adsorbed CH{sub 3} and adsorbed H. Results documents a new mechanism for a surface reaction, a reaction between an adsorbed and a bulk species, and demonstrates the importance of bulk H as a reactant in a heterogeneous catalytic reaction.

Ceyer, S.T.

1992-12-31T23:59:59.000Z

59

Catalysis: Reactivity and Structure Group | Chemistry Department |  

NLE Websites -- All DOE Office Websites (Extended Search)

Group Members Group Members Principal Investigators Jose Rodriguez Catalysis and surface science. Interaction and reaction of molecules with surfaces of metals, oxides, sulfides and carbides. Use of synchrotron-based techniques in surface and materials characterization (core and valence photoemission, x-ray absorption spectroscopy, x-ray diffraction). Modeling of surface reactions. Ping Liu Theoretical description of nanostructures, supported nanostructures, surfaces and their catalytic applications in heterogeneous catalysis and electrocatalysis. Density functional calculations, kinetic modeling and sensitivity analysis are employed to obtain a fundamental understanding of catalytic processes Dario Stacchiola Nano-Catalysis, Model mixed metal oxides, In-situ catalytic reactions at ambient pressures (AP). (Synchrotron PES, AP-XPS, AP-STM, AP-IRRAS, Inverse Catalyst, Nanoparticles, Graphene)

60

Catalysis Science at Brookhaven  

NLE Websites -- All DOE Office Websites (Extended Search)

and energy conversion. Reactivity-structure correlations explored and unraveled by utilization of synchrotron radiation are a key aspect of these studies. Catalysis on the...

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

Toward computational screening in heterogeneous catalysis - TMS  

Science Conference Proceedings (OSTI)

Sep 11, 2007 ... This article describes the use of DFT calculations on multiple catalytic surfaces to obtain a specified "descriptor," a calculated value that can ...

62

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

DOE Green Energy (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

63

Center for Catalysis at Iowa State University  

Science Conference Proceedings (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

64

Shining Light on Catalysis | Stanford Synchrotron Radiation Lightsource  

NLE Websites -- All DOE Office Websites (Extended Search)

Shining Light on Catalysis Shining Light on Catalysis Tuesday, July 19, 2011 - 4:38pm SSRL Conference Room 137-322 Jeroen A. van Bokhoven, Professor for Heterogeneous Catalysis Institute for Chemical and Bioengineering ETH Zurich Head of Laboratory for Catalysis and Sustainable Chemistry (LSK) Swiss Light Source Paul Scherrer Institute Understanding a functioning catalyst requires understanding at the atomic scales in a time-resolved manner. X-rays can be readily used to accomplish that task, because of the large penetration depth of hard X-rays, in situ or operando experiments are possible. In addition, complementary techniques, such as the vibrational spectroscopies can be simultaneously applied. Recent development in instrumentation to perform quick EXAFS and secondary emission spectroscopy has provided exciting new opportunities to

65

Heterogeneous particle swarm optimizers  

Science Conference Proceedings (OSTI)

Particle swarm optimization (PSO) is a swarm intelligence technique originally inspired by models of flocking and of social influence that assumed homogeneous individuals. During its evolution to become a practical optimization tool, some heterogeneous ...

Marco A. Montes De Oca; Jorge Peña; Thomas Stützle; Carlo Pinciroli; Marco Dorigo

2009-05-01T23:59:59.000Z

66

Energy Programs | Catalysis  

NLE Websites -- All DOE Office Websites (Extended Search)

Catalysis Catalysis Driving Toward Alternative Fuels Page 1 of 2 About 85 percent of the nation's energy needs are met by the combustion of fossil fuels such as oil, natural gas, and coal - finite resources that make the United States dependent upon other countries while polluting the environment through carbon emissions. In order to achieve energy security in an environmentally friendly manner, the nation's energy strategy must include alternative technologies based on renewable sources such as biofuels, solar, wind, and nuclear power. A central challenge, however, is the development of new processes and materials capable of tapping these sources and feeding the country's vast energy needs. A key part of the solution involves catalysis, the process of speeding up and

67

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

Science Conference Proceedings (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

68

Chapter 1 Introduction 1.1. HOMOGENEOUS CATALYSIS  

E-Print Network (OSTI)

acid Pt/Rh nets 1940 Catalytic reforming of hydrocarbons (gasoline) Pt/Al2O3 1940 Benzene hydrogenation

Groningen, Rijksuniversiteit

69

Jeffrey T. Miller Wins Award for Excellence in Catalysis  

NLE Websites -- All DOE Office Websites (Extended Search)

van Veenendaal of X-ray Science Division wins 2009 NIU Presidential van Veenendaal of X-ray Science Division wins 2009 NIU Presidential Research Professorship 2009 APSUO Compton Award to Grübel, Mochrie, and Sutton New Era of Research Begins as World's First Hard X-ray Laser Achieves "First Light" Unique Uranium Source in Naturally Bioreduced Sediment Jonathan Lang Named 2008 PSC Supervisor of the Year APS News Archives: 2012 | 2011 | 2010 | 2009 2008 | 2007 | 2006 | 2005 2004 | 2003 | 2002 | 2001 2000 Subscribe to APS News rss feed Jeffrey T. Miller Wins Award for Excellence in Catalysis JUNE 15, 2009 Bookmark and Share Jeffrey T. Miller Jeffrey T. Miller, leader of the Heterogeneous Catalysis Group in the Argonne National Laboratory Chemical Sciences and Engineering Division (CSE), has been presented with the 2009 Award for Excellence in Catalysis

70

DNA-based asymmetric catalysis.  

E-Print Network (OSTI)

??The goal of the research described in this thesis was to develop the general concept and methodology of DNA-based asymmetric catalysis, with the aim of… (more)

Boersma, Arnold Jacob

2009-01-01T23:59:59.000Z

71

BNL | CFN: Interface Science & Catalysis  

NLE Websites -- All DOE Office Websites (Extended Search)

Interface Science & Catalysis Contact: Peter Sutter The world is facing unprecedented challenges in satisfying a rapidly growing demand for energy while reducing negative impacts...

72

Fuel Cell Technologies Office: Catalysis Working Group  

NLE Websites -- All DOE Office Websites (Extended Search)

Catalysis Working Catalysis Working Group to someone by E-mail Share Fuel Cell Technologies Office: Catalysis Working Group on Facebook Tweet about Fuel Cell Technologies Office: Catalysis Working Group on Twitter Bookmark Fuel Cell Technologies Office: Catalysis Working Group on Google Bookmark Fuel Cell Technologies Office: Catalysis Working Group on Delicious Rank Fuel Cell Technologies Office: Catalysis Working Group on Digg Find More places to share Fuel Cell Technologies Office: Catalysis Working Group on AddThis.com... Key Activities Plans, Implementation, & Results Accomplishments Organization Chart & Contacts Quick Links Hydrogen Production Hydrogen Delivery Hydrogen Storage Fuel Cells Technology Validation Manufacturing Codes & Standards Education Systems Analysis

73

Instrumentation @ Catalysis: Reactivity and Structure Group | Chemistry  

NLE Websites -- All DOE Office Websites (Extended Search)

Instrumentation Instrumentation The Catalysis Group at BNL is leading research initiatives into the development of new tools and techniques that focus on the characterization of heterogeneous catalytic reactions and catalysts using imaging, spectroscopy and scattering techniques and integrated combinations of them under reaction conditions to unravel the morphology, chemical and structural properties, of catalysts, respectively. These efforts revolve around the use of synchrotron radiation (NSLS), electrons (CFN) and quantum tunneling tools with particular thrusts into imaging, spectroscopy and scattering. Groups Instrumentation(BNL) Three UHV chambers with diverse instrumentation for surface characterization: LEED, UPS, XPS, AES, TPD, ISS, PM-AP-IRRAS, Reactivity Cell. All the systems include ancillary instrumentation such as sputtering guns and metal evaporators. The IRRAS system was retrofitted with an ambient pressure (AP) cell on top of the UHV system. The sample can be prepared and characterized in UHV and then transfer in vacuum to the AP cell.

74

Enhanced Micellar Catalysis LDRD.  

SciTech Connect

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

75

Fuel Synthesis Catalysis Laboratory (Fact Sheet)  

DOE Green Energy (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

76

Fuel Synthesis Catalysis Laboratory (Fact Sheet)  

SciTech Connect

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

77

Argonne Chemical Sciences & Engineering - Publications - Catalysis...  

NLE Websites -- All DOE Office Websites (Extended Search)

News & Highlights Events Search Argonne ... Search Argonne Home > Chemical Sciences & Engineering > Fundamental Interactions Catalysis & Energy Conversion Electrochemical...

78

Argonne Chemical Sciences & Engineering - People - Catalysis...  

NLE Websites -- All DOE Office Websites (Extended Search)

News & Highlights Events Search Argonne ... Search Argonne Home > Chemical Sciences & Engineering > Fundamental Interactions Catalysis & Energy Conversion Electrochemical...

79

Available Technologies: Nanocrystal Assembly for Tandem Catalysis  

APPLICATIONS OF TECHNOLOGY: Industrial catalysis; Development of artificial photosynthesis; Multiple-step chemical reactions ; ADVANTAGES: Enables reactions requiring ...

80

EMSL and Institute for Integrated Catalysis (IIC) Catalysis Workshop  

DOE Green Energy (OSTI)

Within the context of significantly accelerating scientific progress in research areas that address important societal problems, a workshop was held in November 2010 at EMSL to identify specific and topically important areas of research and capability needs in catalysis-related science.

Campbell, Charles T.; Datye, Abhaya K.; Henkelman, Graeme A.; Lobo, Raul F.; Schneider, William F.; Spicer, Leonard D.; Tysoe, Wilfred T.; Vohs, John M.; Baer, Donald R.; Hoyt, David W.; Thevuthasan, Suntharampillai; Mueller, Karl T.; Wang, Chong M.; Washton, Nancy M.; Lyubinetsky, Igor; Teller, Raymond G.; Andersen, Amity; Govind, Niranjan; Kowalski, Karol; Kabius, Bernd C.; Wang, Hongfei; Campbell, Allison A.; Shelton, William A.; Bylaska, Eric J.; Peden, Charles HF; Wang, Yong; King, David L.; Henderson, Michael A.; Rousseau, Roger J.; Szanyi, Janos; Dohnalek, Zdenek; Mei, Donghai; Garrett, Bruce C.; Ray, Douglas; Futrell, Jean H.; Laskin, Julia; DuBois, Daniel L.; Kuprat, Laura R.; Plata, Charity

2011-05-24T23:59:59.000Z

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.


81

Bridge to Fuel Cell Molecular Catalysis: 3D Non-Platinum Group Metal  

NLE Websites -- All DOE Office Websites (Extended Search)

Bridge to Fuel Cell Molecular Catalysis: 3D Non-Platinum Group Metal Bridge to Fuel Cell Molecular Catalysis: 3D Non-Platinum Group Metal Catalyst in MEAs Title Bridge to Fuel Cell Molecular Catalysis: 3D Non-Platinum Group Metal Catalyst in MEAs Publication Type Journal Article Year of Publication 2012 Authors Zhu, Xiaobing, John B. Kerr, Qinggang He, Gi Suk Hwang, Zulima Martin, Kyle Clark, Adam Z. Weber, and Nana Zhao Journal ECS Transactions Volume 45 Issue 2 Pagination 143 - 152 Date Published 04/2012 ISSN 1938-6737 Abstract Transition metal porphyrin complexes have been mounted in a three dimensional homogenous distribution inside the ionomer of catalyst layers in MEAs to achieve competitive fuel cell catalysis activity. The effect of electrode components including ionomer, carbon, catalyst, and mediator, and ionomer film thickness, is investigated in fuel cell molecular catalysis system. Membrane electrode assembly (MEA) durability testing has been conducted. SEM and TEM techniques are employed to investigate molecular catalysis electrode micro- and nano- structure and morphology. To date, surprisingly, the best fuel cell performance, i.e. 1280 mA/cm2 of maximum/short-circuit current density is achieved, approaching that of Pt-based electrode, indicating higher turnover frequencies than Pt although with poorer voltages.

82

Charge Transfer and Support Effects in Heterogeneous Catalysis  

E-Print Network (OSTI)

S.  J. ; Fung, S.  C. ; Garten, R.  L.  J.  Am.  Chem.  S.  J. ; Fung, S.  C. ; Garten, R.  L.  J.  Am.  Chem.  S.  J. ; Fung, S.  C. ; Garten, R.  L.  J.  Am.  Chem.  

Hervier, Antoine

2012-01-01T23:59:59.000Z

83

Charge Transfer and Support Effects in Heterogeneous Catalysis  

E-Print Network (OSTI)

closely followed the  solar  spectrum.   On  a  typical closely followed the solar spectrum.   A batch mode reactor followed the solar spectrum.   Electrical  connections 

Hervier, Antoine

2012-01-01T23:59:59.000Z

84

Basic Research Needs: Catalysis for Energy  

DOE Green Energy (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

85

Argonne Chemical Sciences & Engineering - Catalysis & Energy...  

NLE Websites -- All DOE Office Websites (Extended Search)

* Fuel Quality Issues * Production of Hydrogen using Copper-Chlorine Cycle Catalysis & Energy Conversion Home Fuel Cell Engineering A bread-board apparatus was tested to study...

86

Resonant Polarized Radiation Catalysis, and the Expansion  

Science Conference Proceedings (OSTI)

Presentation Title, The Birth of a New Field of Materials Science: Resonant Polarized Radiation Catalysis, and the Expansion of Thermodynamics. Author(s)  ...

87

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

NLE Websites -- All DOE Office Websites (Extended Search)

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

88

Catalysis on the Nanoscale: Preparation, Characterization and...  

NLE Websites -- All DOE Office Websites (Extended Search)

Catalysis on the Nanoscale: Preparation, Characterization and Reactivity of Metal-Based Nanostructures The purpose of this program is to explore and manipulate the size, morphology...

89

Dr. Karl Irikura  

Science Conference Proceedings (OSTI)

... His undergraduate research was in biomolecular simulations (with M. Karplus) and in heterogeneous and homogeneous catalysis (with SJ Tauster ...

2013-02-14T23:59:59.000Z

90

Iron catalysis in oxidation by ozone - Energy Innovation Portal  

Bookmark Iron catalysis in oxidation by ozone - Energy Innovation Portal on Google; Bookmark Iron catalysis in oxidation by ozone - Energy Innovation ...

91

LDRD final report on new homogeneous catalysts for direct olefin epoxidation (LDRD 52591).  

DOE Green Energy (OSTI)

This report summarizes our findings during the study of a novel homogeneous epoxidation catalyst system that uses molecular oxygen as the oxidant, a ''Holy Grail'' in catalysis. While olefins (alkenes) that do not contain allylic hydrogens can be epoxidized directly using heterogeneous catalysts, most olefins cannot, and so a general, atom-efficient route is desired. While most of the work performed on this LDRD has been on pincer complexes of late transition metals, we also scouted out metal/ligand combinations that were significantly different, and unfortunately, less successful. Most of the work reported here deals with phosphorus-ligated Pd hydrides [(PCP)Pd-H]. We have demonstrated that molecular oxygen gas can insert into the Pd-H bond, giving a structurally characterized Pd-OOH species. This species reacts with oxygen acceptors such as olefins to donate an oxygen atom, although in various levels of selectivity, and to generate a [(PCP)Pd-OH] molecule. We discovered that the active [(PCP)Pd-H] active catalyst can be regenerated by addition of either CO or hydrogen. The demonstration of each step of the catalytic cycle is quite significant. Extensions to the pincer-Pd chemistry by attaching a fluorinated tail to the pincer designed to be used in solvents with higher oxygen solubilities are also presented.

Goldberg, Karen (University of Washington); Smythe, Nicole A. (University of Washington); Moore, Joshua T.; Stewart, Constantine A.; Kemp, Richard Alan; Miller, James Edward; Kornienko, Alexander (New Mexico Institute of Mining and Technology); Denney, Melanie C. (University of Washington); Cetto, Kara L. (University of Washington)

2006-02-01T23:59:59.000Z

92

"Nanocrystal bilayer for tandem catalysis"  

DOE Green Energy (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

93

AN EXPERIMENTAL INVESTIGATION OF FOAM FLOW IN HOMOGENEOUS AND HETEROGENEOUS  

E-Print Network (OSTI)

in the sand pack was 100-120 mesh Ottawa sand. To ensure good settling, pneumatic vibrators were used while and connected to a transducer modulator. Electrical signals obtained from the transducer modulator were volumes were injected. Any gas that accumulated within the connection tubes between the sand pack

94

Advanced Resources for Catalysis Science; Recommendations for a National Catalysis Research Institute  

DOE Green Energy (OSTI)

Catalysis is one of the most valuable contributors to our economy and historically an area where the United States has enjoyed, but is now losing, international leadership. While other countries are stepping up their work in this area, support for advanced catalysis research and development in the U.S. has diminished. Yet, more than ever, innovative and improved catalyst technologies are imperative for new energy production processes to ease our dependence on imported resources, for new energy-efficient and environmentally benign chemical production processes, and for new emission reduction technologies to minimize the environmental impact of an active and growing economy. Addressing growing concerns about the future direction of U.S. catalysis science, experts from the catalysis community met at a workshop to determine and recommend advanced resources needed to address the grand challenges for catalysis research and development. The workshop's primary conclusion: To recapture our position as the leader in catalysis innovation and practice, and promote crucial breakthroughs, the U.S. must establish one or more well-funded and well-equipped National Catalysis Research Institutes competitively selected, centered in the national laboratories and, by charter, networked to other national laboratories, universities, and industry. The Institute(s) will be the center of a national collaboratory that gives catalysis researchers access to the most advanced techniques available in the scientific enterprise. The importance of catalysis to our energy, economic, and environmental security cannot be overemphasized. Catalysis is a vital part of our core industrial infrastructure, as it is integral to chemical processing and petroleum refining, and is critical to proposed advances needed to secure a sustainable energy future. Advances in catalysis could reduce our need for foreign oil by making better use of domestic carbon resources, for example, allowing cost-effective and zero emission conversion of coal into transportation fuels. No matter what energy sources are being considered (oil, natural gas, coal, biomass, solar, or nuclear based), a clean, sustainable energy future will involve catalysis to improve energy efficiency and storage and use options, and to mitigate environmental impacts. Recent revolutionary advances in nanotechnology and high-performance computing are enabling the breakthroughs in catalysis science and technology essential for a secure energy future. Thus, the time is right for substantially increased investments in catalysis science and technology.

Peden, Charles HF.; Ray, Douglas

2005-10-05T23:59:59.000Z

95

Argonne Chemical Sciences & Engineering - Catalysis & Energy...  

NLE Websites -- All DOE Office Websites (Extended Search)

or heterogeneous (where the reactants and catalysts are in separate phases--normally gas or liquids over solids). Heterogeneous catalysts act in a different phase than the...

96

Heterogeneous wireless sensor network deployment and topology control based on irregular sensor model  

Science Conference Proceedings (OSTI)

Heterogeneous wireless sensor network (heterogeneous WSN) consists of sensor nodes with different ability, such as different computing power and sensing range. Compared with homogeneous WSN, deployment and topology control are more complex in heterogeneous ... Keywords: heterogeneous sensor deployment, irregular sensor model, sensor coverage, topology control, wireless sensor network

Chun-Hsien Wu; Yeh-Ching Chung

2007-05-01T23:59:59.000Z

97

Fuel Cell Technologies Office: Catalysis Working Group Kick-Off...  

NLE Websites -- All DOE Office Websites (Extended Search)

Catalysis Working Group Kick-Off Meeting: May 2012 to someone by E-mail Share Fuel Cell Technologies Office: Catalysis Working Group Kick-Off Meeting: May 2012 on Facebook Tweet...

98

Fuel Cell Technologies Office: Catalysis Working Group  

NLE Websites -- All DOE Office Websites (Extended Search)

Catalysis Working Group Catalysis Working Group The Catalysis Working Group (CWG) meets twice per year to exchange information, create synergies, and collaboratively develop both an understanding of and tools for studying electrocatalysis for polymer electrolyte fuel cells (PEFCs) and other low- and intermediate-temperature fuel cell systems, including direct methanol fuel cells (DMFCs), alkaline fuel cells (AFCs), alkaline membrane fuel cells (AMFCs), and phosphoric acid fuel cells (PAFCs). The CWG members include principal and co-principal investigators in electrocatalysis projects funded by the U.S. Department of Energy (DOE), as well as supporting DOE personnel. More information on DOE electrocatalysis activities can be found in the Multi-Year Research, Development, and Demonstration Plan.

99

Opportunities in Catalysis Research Using Synchrotron Radiation  

NLE Websites -- All DOE Office Websites (Extended Search)

in Catalysis Research Using Synchrotron Radiation in Catalysis Research Using Synchrotron Radiation Tuesday 10/8/02 Chair: Lars Pettersson 1:30-1:40 Anders Nilsson Welcome 1:40-2:30 Gabor Somorjai University of California, Berkeley and LBLN Need for New Directions of Research at the Frontiers of Catalysis Science 2:30-3:00 Geoff Thornton University of Manchester Influence of defects on the reactivity of ZnO 3:00-3:30 Anders Nilsson Stanford Synchrotron Radiation Laboratory Soft X-ray Spectroscopy of Surfaces and Reactions 3:30-3:45 Break Chair: Anders Nilsson 3:45-4:15 Lars Pettersson Stockholm University Adsorbate-Substrate Bonding: An Experimental and Theoretical MO Picture 4:15-4:45 Miquel Salmeron Lawrence Berkeley National Laboratory Photoelectron Spectroscopy studies of surfaces in high pressure gas

100

Iron Catalysis in Oxidations by Ozone - Energy Innovation Portal  

Wind Energy; Partners (27) Visual Patent Search; Success Stories; News; Events; Industrial Technologies Iron Catalysis in Oxidations by Ozone Ames ...

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

Nucleation Catalysis Potency of Ceramic Nanoparticles in Aluminum ...  

Science Conference Proceedings (OSTI)

Symposium, Frontiers in Solidification Science. Presentation Title, Nucleation Catalysis Potency of Ceramic Nanoparticles in Aluminum Matrix Nanocomposites .

102

Designing a unified programming model for heterogeneous machines  

Science Conference Proceedings (OSTI)

While high-efficiency machines are increasingly embracing heterogeneous architectures and massive multithreading, contemporary mainstream programming languages reflect a mental model in which processing elements are homogeneous, concurrency is limited, ...

Michael Garland; Manjunath Kudlur; Yili Zheng

2012-11-01T23:59:59.000Z

103

Heterogeneous breast phantom development for microwave imaging using regression models  

Science Conference Proceedings (OSTI)

As new algorithms for microwave imaging emerge, it is important to have standard accurate benchmarking tests. Currently, most researchers use homogeneous phantoms for testing new algorithms. These simple structures lack the heterogeneity of the dielectric ...

Camerin Hahn; Sima Noghanian

2012-01-01T23:59:59.000Z

104

Model Catalysts: Simulating the Complexities of Heterogeneous Catalysts  

Science Conference Proceedings (OSTI)

Surface-science investigations have contributed significantly to heterogeneous catalysis in the past several decades. Fundamental studies of reactive systems on metal single crystals have aided researchers in understanding the effect of surface structure on catalyst reactivity and selectivity for a number of important reactions. Recently, model systems, consisting of metal clusters deposited on planar oxide surfaces, have facilitated the study of metal particle-size and support effects. These model systems not only are useful for carrying out kinetic investigations, but are also amenable to surface spectroscopic techniques, thus enabling investigations under realistic pressures and at working temperatures. By combining surface-science characterization methods with kinetic measurements under realistic working conditions, researchers are continuing to advance the molecular-level understanding of heterogeneous catalysis and are narrowing he pressure and material gap between model and real-world catalysts.

Gao, Feng; Goodman, D. W.

2012-05-01T23:59:59.000Z

105

HOMOGENEOUS NUCLEAR POWER REACTOR  

DOE Patents (OSTI)

A homogeneous nuclear power reactor utilizing forced circulation of the liquid fuel is described. The reactor does not require fuel handling outside of the reactor vessel during any normal operation including complete shutdown to room temperature, the reactor being selfregulating under extreme operating conditions and controlled by the thermal expansion of the liquid fuel. The liquid fuel utilized is a uranium, phosphoric acid, and water solution which requires no gus exhaust system or independent gas recombining system, thereby eliminating the handling of radioiytic gas.

King, L.D.P.

1959-09-01T23:59:59.000Z

106

HOMOGENEOUS NUCLEAR REACTOR  

SciTech Connect

This homogeneous reactor comprises a core occupied by a solution of a fissile material in a moderator liquid and a breeder region enclosing the core and having a suspension of fertile material in the same moderator liquid. There is communication between the core and breeder to allow mass transfer and pressure equalization between the regions. The zones each have a separate circuit for removing heat by a mixer chamber situated inside the reactor vessel. The effluents coming from the two regions are mixed and led to a common device for separation into a clear solution and suspension, which are each led back to its corresponding circuit. To control the relative concentration of the two regions, an evaporator is provided separating a part of the moderator liquid from the solution occupying the core, the condensed separated moderator liquid being led into the breeder region. (NPO)

1960-07-11T23:59:59.000Z

107

HOMOGENEOUS NUCLEAR REACTOR  

DOE Patents (OSTI)

Nuclear reactors of the homogeneous liquid fuel type are discussed. The reactor is comprised of an elongated closed vessel, vertically oriented, having a critical region at the bottom, a lower chimney structure extending from the critical region vertically upwardly and surrounded by heat exchanger coils, to a baffle region above which is located an upper chimney structure containing a catalyst functioning to recombine radiolyticallydissociated moderator gages. In operation the liquid fuel circulates solely by convection from the critical region upwardly through the lower chimney and then downwardly through the heat exchanger to return to the critical region. The gases formed by radiolytic- dissociation of the moderator are carried upwardly with the circulating liquid fuel and past the baffle into the region of the upper chimney where they are recombined by the catalyst and condensed, thence returning through the heat exchanger to the critical region.

Hammond, R.P.; Busey, H.M.

1959-02-17T23:59:59.000Z

108

Nanoscale Advances in Catalysis and Energy Applications  

SciTech Connect

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

109

USD Catalysis Group for Alternative Energy  

DOE Green Energy (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

110

Bilipschitz Homogeneity and Jordan Curves.  

E-Print Network (OSTI)

??We analyze Jordan curves in the plane that are bilipschitz homogeneous with respect to Euclidean distance and/or inner diameter distance. We begin our analysis from… (more)

Freeman, David M.

2009-01-01T23:59:59.000Z

111

Materials Design and Discovery: Catalysis and Energy Storage...  

NLE Websites -- All DOE Office Websites (Extended Search)

for propylene epoxidation. Larry Curtiss Materials Design and Discovery: Catalysis and Energy Storage PI Name: Larry Curtiss PI Email: curtiss@anl.gov Institution: Argonne...

112

Workshop on Catalysis Research at the Advanced Photon Source  

NLE Websites -- All DOE Office Websites (Extended Search)

Catalysis Workshop Home Program Registration Poster Registration Organizing Committee: * Chris Marshall (ANL) * Peter Stair (NWU) * Simon Bare (UOP) * Hoydoo You (ANL) * Randy...

113

Application of Alum from Kankara Kaolinite in Catalysis  

Science Conference Proceedings (OSTI)

Presentation Title, Application of Alum from Kankara Kaolinite in Catalysis: A Preliminary Report. Author(s), Lawrence Chukwuka Edomwonyi-Otu, Benjamin ...

114

Argonne Chemical Sciences & Engineering - People - Catalysis...  

NLE Websites -- All DOE Office Websites (Extended Search)

State University 25+ years of industrial research at BP Heterogeneous catalyst fundamentals Synthesis of supported metal catalysts Reaction kinetics and pathways Acid...

115

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

116

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.

117

Microgrids and Heterogeneous Power Quality and Reliability  

Science Conference Proceedings (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

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

NLE Websites -- All DOE Office Websites (Extended Search)

Heterogeneous and Homogeneous Freezing Heterogeneous and Homogeneous Freezing Parameterizations on Tropical Anvil Characteristics and Water Vapor Content of the TTL Jiwen Fan Climate Physics, Pacific Northwest National Laboratory Contributed by: Jennifer Comstock, Mikhail Ovtchinnikov, Sally McFarlane, and Greg McFarquhar OBJECTIVES Look into the effects of the commonly used heterogeneous and homogeneous freezing parameterizations on anvil properties and water vapor content in the TTL for the deep convective clouds developed in the contrasting environments. Examine the impact of the immersion-freezing on homogeneous freezing process. Homogeneous freezing parameterizations (HFPs) 1) Koop et al. (2000): J r depends on the water activity of the solution and is independent of the nature of solute.

119

Mississippi State Biodiesel Production Project  

DOE Green Energy (OSTI)

Heterogeneous catalysis was examined as an alternative to overcome the disadvantages of homogeneous transesterification, such as the presence of salts in the glycer

Rafael Hernandez; Todd French; Sandun Fernando; Tingyu Li; Dwane Braasch; Juan Silva; Brian Baldwin

2008-03-20T23:59:59.000Z

120

THE HOMOGENEOUS SUSPENSION REACTOR PROJECT  

SciTech Connect

The considerations which led to the study of a homogeneous suspension reactor are reviewed briefly. The characteristics of the KEMA Suspension Test Reactor (KSTR) are then summarized. (J.S.R.)

Went, J.J.

1963-02-01T23:59:59.000Z

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.


121

Catalysis: Reactivity and Structure Group | Chemistry Department...  

NLE Websites -- All DOE Office Websites (Extended Search)

apply new approaches for the in-situ characterization of heterogeneous catalysts using facilities available at the National Synchrotron Light Source for X-ray diffraction, X-ray...

122

Wetting of a Chemically Heterogeneous Surface  

Science Conference Proceedings (OSTI)

Theories for inhomogeneous fluids have focused in recent years on wetting, capillary conden- sation, and solvation forces for model systems where the surface(s) is(are) smooth homogeneous parallel plates, cylinders, or spherical drops. Unfortunately natural systems are more likely to be hetaogeneous both in surt%ce shape and surface chemistry. In this paper we discuss the conse- quences of chemical heterogeneity on wetting. Specifically, a 2-dimensional implementation of a nonlocal density functional theory is solved for a striped surface model. Both the strength and range of the heterogeneity are varied. Contact angles are calculated, and phase transitions (both the wetting transition and a local layering transition) are located. The wetting properties of the surface ase shown to be strongly dependent on the nature of the surface heterogeneity. In addition highly ordered nanoscopic phases are found, and the operational limits for formation of ordered or crystalline phases of nanoscopic extent are discussed.

Frink, L.J.D.; Salinger, A.G.

1998-11-20T23:59:59.000Z

123

Catalysis Science | U.S. DOE Office of Science (SC)  

Office of Science (SC) Website

Catalysis Science Catalysis Science Chemical Sciences, Geosciences, & Biosciences (CSGB) Division CSGB Home About Research Areas Energy Frontier Research Centers (EFRCs) DOE Energy Innovation Hubs Scientific Highlights Reports & Activities Principal Investigators' Meetings BES Home Research Areas Catalysis Science Print Text Size: A A A RSS Feeds FeedbackShare Page This research area develops the fundamental scientific principles enabling rational catalyst design and chemical transformation control. Research includes the identification of the elementary steps of catalytic reaction mechanisms and their kinetics; construction of catalytic sites at the atomic level; synthesis of ligands, metal clusters, and bio-inspired reaction centers designed to tune molecular-level catalytic activity and

124

A Parameterization of Heterogeneous Land Surfaces for Atmospheric Numerical Models and Its Impact on Regional Meteorology  

Science Conference Proceedings (OSTI)

Natural land surfaces are usually heterogeneous over the resolvable scales considered in atmospheric numerical models. Therefore, model surface parameterizations that assume surface homogeneity may fail to represent the surface forcing ...

R. Avissar; R. A. Pielke

1989-10-01T23:59:59.000Z

125

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

126

Workflow for Tandem Catalysis in Nanocrystal Interfaces | Department...  

Energy.gov (U.S. Department of Energy (DOE)) Indexed Site

Catalysis in Nanocrystal Interfaces July 18, 2011 - 2:45pm View Edit Workflow(active tab) Current Revision Status published Revision 17905 Drafts ID Title Status Last Updated...

127

Lean NOx Trap Catalysis for Lean Natural Gas Engine Applications  

Science Conference Proceedings (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 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

128

Lean NOx Trap Catalysis for Lean Natural Gas Engine Applications  

DOE Green Energy (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

129

Epoxy Based Nanodielectric with Homogeneously Distributed ...  

Electricity Transmission Advanced Materials Epoxy Based Nanodielectric with Homogeneously Distributed Nanoparticles Oak Ridge National Laboratory. Contact ...

130

Heterogeneous catalysis in fluoride melts: reduction of uranium(V) and niobium(IV) by hydrogen  

DOE Green Energy (OSTI)

The reduction of uranium(V) or niobium(IV) dissolved in fluoride melts at 550/sup 0/C by hydrogen gas in the absence of catalysts exhibits zero-order kinetics, i.e., the quantity reduced per unit time is independent of the concentration of dissolved species or the hydrogen gas partial pressure. Platinum catalysts accelerate the reaction rate 10- to 100-fold and, with uranium(V), the catalyzed reaction exhibits first-order kinetics, suggesting that the catalyzed reaction may be diffusion limited. Platinum was catalytically active when present as platinum black powder, sponge, sheet or powder that has sintered to or alloyed with the gold reaction crucible.

Kelmers, A.D.; Bennett, M.R.

1976-01-01T23:59:59.000Z

131

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

132

The Atomic AXAFS and XANES Techniques as Applied to Heterogeneous Catalysis and Electrocatalysis  

Science Conference Proceedings (OSTI)

X-Ray absorption spectroscopy (XAFS) is an attractive in situ and in operando technique. In recent years, the more conventional extended X-ray absorption fine structure (EXAFS) data analysis technique has been complemented by two newer analysis methods: the 'atomic' XAFS (AXAFS) technique, which analyzes the scattering from the absorber atom itself, and the {Delta}{mu} XANES technique, which uses a difference method to isolate the changes in the X-ray absorption near edge structure (XANES) due to adsorbates on a metal surface. With AXAFS it is possible to follow the electronic effect a support has on a metal particle; with {Delta}{mu} XANES it is possible to determine the adsorbate, the specific adsorption sites and adsorbate coverage on a metal catalyst. This unprecedented new information helps a great deal to unravel the complex kinetic mechanisms operating in working reactors or fuelcell systems. The fundamental principles and methodology for applying the AXAFS and {Delta}{mu} XANES techniques are given here, and then specific applications are summarized, including H adsorption on supported Pt in the gas phase, wateractivation at a Pt cathode and methanol oxidation at a Pt anode in an electrochemical cell, sulfur oxidation on Pt, and oxygenreduction on a Au/SnO{sub x} cathode. Finally, the future outlook for time and/or space resolved applications of these techniques is contemplated.

Ramaker, D.; Koningsberger, D

2010-01-01T23:59:59.000Z

133

Heterogeneous Catalysis on Atomically Dispersed Supported Metals: CO2 Reduction on Multifunctional Pd Catalysts  

Science Conference Proceedings (OSTI)

Temperature programmed reaction and scanning transmission electron microscopy experiments were applied to prove the requirement of two different catalyst functionalities for the reduction of CO2 with hydrogen on Pd/Al2O3 and Pd/MWCNT catalysts. The research described in this paper was supported by the Laboratory Directed Research and Development (LDRD) program of the Pacific Northwest National Laboratory (PNNL) and was performed at the Environmental Molecular Sciences Laboratory (EMSL), a national scientific user facility sponsored by the DOE’s Office of Biological and Environmental Research and located at PNNL. PNNL is operated for the US DOE by Battelle Memorial Institute.

Kwak, Ja Hun; Kovarik, Libor; Szanyi, Janos

2013-11-01T23:59:59.000Z

134

Upscaled flow and transport properties for heterogeneous unsaturated media  

E-Print Network (OSTI)

Federal Services, Richland, Washington, USA T.-C. Jim Yeh Department of Hydrology and Water Resources behavior at the field scale [Yeh, 1998]. However, to represent a heterogeneous medium by its homogeneous the effective properties for partially saturated media. Theoretical work [e.g., Mualem, 1984; Yeh et al., 1985a

Lu, Zhiming

135

Modelling Heterogeneous Dispersion in Marginal Models for Longitudinal Proportional Data  

E-Print Network (OSTI)

the fitted curves for the pattern of dispersion profile over time across three different gas concentrationModelling Heterogeneous Dispersion in Marginal Models for Longitudinal Proportional Data Peter X proportional data assumes a constant dispersion para- meter. This assumption of dispersion homogeneity

Song, Peter X.

136

Microgrids and Heterogeneous Power Quality and Reliability: Matching the  

E-Print Network (OSTI)

LBNL-63524 Microgrids and Heterogeneous Power Quality and Reliability: Matching the Quality under review by the Transactions of the Industry Applications Society of IEE Japan 1 Microgrids of universal homogeneous supply upstream in the grid. Finally, the potential role of microgrids in delivering

137

Publications @ Catalysis: Reactivity and Structure Group | Chemistry  

NLE Websites -- All DOE Office Websites (Extended Search)

List of Publications since 2010 List of Publications since 2010 2013 "Unique properties of ceria nanoparticles supported on metals: Novel inverse ceria/copper catalysts for CO oxidation and the water-gas shift reaction" Senanayake, S.D., Stacchiola, D., and Rodriguez, J.A. Accounts of Chemical Research, 2013. 46(8): p. 1702-1711. "Characterization of metal-oxide catalysts in operando conditions by combining x-ray absorption and raman spectroscopies in the same experiment" Patlolla, A., Baumann, P., Xu, W., Senanayake, S.D., Rodriguez, J.A., and Frenkel, A.I. Topics in Catalysis, 2013. 56(11): p. 896-904. "In situ time-resolved x-ray diffraction study of the synthesis of Mo2C with different carburization agents" Guzman, H.J., Xu, W.Q., Stacchiola, D., Vitale, G., Scott, C.E., Rodriguez, J.A., and Pereira-Almao, P. Canadian Journal of Chemistry-Revue Canadienne De Chimie, 2013. 91(7): p. 573-582.

138

Some General Themes in Catalysis at LANL  

DOE Green Energy (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

139

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

E-Print Network (OSTI)

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

O. Yaremko.; E. Mogileva

2013-09-24T23:59:59.000Z

140

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

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

Exhaust aftertreatment using plasma-assisted catalysis  

DOE Green Energy (OSTI)

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

Penetrante, B

2000-01-20T23:59:59.000Z

142

High-Spin Cobalt Hydrides for Catalysis  

SciTech Connect

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

Catalysis-by-design impacts assessment  

SciTech Connect

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

144

PNNL: Institute for Integrated Catalysis (IIC) at Pacific Northwest  

NLE Websites -- All DOE Office Websites (Extended Search)

Institute for Integrated Catalysis Institute for Integrated Catalysis The Institute for Integrated Catalysis at Pacific Northwest National Laboratory facilitates collaborative research and development in catalysts for a secure energy future. Latest Announcements When Less Is More: Fewer Proton Relays Improve Catalytic Rates First direct comparison of three nickel-based complexes shows complexes with 2 proton relays outperform those with 4 (January 2014) Wind and other renewable energy sources are limited because the power must be used when it's generated, as it currently cannot be stored. Scientists want to store the energy in compact, easy-to-release chemical bonds. A major challenge is designing an affordable, efficient, and fast catalyst to make the chemical bonds. At the Center for Molecular Electrocatalysis,

145

Tandem Catalysis in Nanocrystal Interfaces | Department of Energy  

Energy.gov (U.S. Department of Energy (DOE)) Indexed Site

Tandem Catalysis in Nanocrystal Interfaces Tandem Catalysis in Nanocrystal Interfaces Tandem Catalysis in Nanocrystal Interfaces July 18, 2011 - 2:45pm View(active tab) Edit Workflow Addthis A unique new bilayer nanocatalyst system. | Image courtesy of Yang group A unique new bilayer nanocatalyst system. | Image courtesy of Yang group What does this mean for me? A prime example of these applications is artificial photosynthesis -- the effort to capture energy from the sun and transform it into electricity or chemical fuels. Catalysts (substances that speed up the rates of chemical reactions without themselves being chemically changed) are used to initiate virtually every industrial manufacturing process that involves chemistry. With the advent of nano-sized catalysts, metal and metal oxide catalysts have surged in

146

Theoretical Study on Catalysis by Protein Enzymes and Ribozyme  

NLE Websites -- All DOE Office Websites (Extended Search)

Theoretical Study on Theoretical Study on Catalysis by Protein Enzymes and Ribozyme Theoretical Study on Catalysis by Protein Enzymes and Ribozyme 2000 NERSC Annual Report 17shkarplus.jpg The energetics were determined for three mechanisms proposed for TIM catalyzed reactions. Results from reaction path calculations suggest that the two mechanisms that involve an enediol intermediate are likely to occur, while the direct intra-substrate proton transfer mechanism (in green) is energetically unfavorable due to the presence of His95 in the active site. Principal Investigator: Martin Karplus, Harvard University Research Objectives The goal of this project is to develop a greater understanding of the mechanisms involved in enzyme catalysis and related protein functions. We are studying two types of enzymes: proteins and a nucleic acid (hammerhead

147

Towards heterogeneous distributed debugging  

Science Conference Proceedings (OSTI)

Several years of research and development in parallel debugger design have given up several techniques, though implemented in a wide range of tools for an equally wide range of systems. This paper is an evaluation of these myriad techniques as applied to the design of a heterogeneous distributed debugger. The evaluation is based on what features users perceive as useful, as well as the ease of implementation of the features using the available technology. A preliminary architecture for such a heterogeneous tool is proposed. Our effort in this paper is significantly different from the other efforts at creating portable and heterogeneous distributed debuggers in that we concentrate on support for all the important issues in parallel debugging, instead of simply concentrating on portability and heterogeneity.

Damodaran-Kamal, S.K.

1995-04-01T23:59:59.000Z

148

Computationally Optimized Homogenization Heat Treatment of ...  

usually entails numerous samples, substantial furnace time and associated energy, ... to optimize the homogenization process for efficiency and cost ...

149

Coherence delay augmented laser beam homogenizer  

SciTech Connect

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

150

MRI of Heterogeneous Hydrogenation Reactions Using Parahydrogen Polarization  

SciTech Connect

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

151

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

SciTech Connect

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

152

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.

153

Heterogeneous waste processing  

DOE Patents (OSTI)

A combination of treatment methods are provided for treatment of heterogeneous waste including: (1) treatment for any organic compounds present; (2) removal of metals from the waste; and, (3) bulk volume reduction, with at least two of the three treatment methods employed and all three treatment methods emplyed where suitable.

Vanderberg, Laura A. (Los Alamos, NM); Sauer, Nancy N. (Los Alamos, NM); Brainard, James R. (Los Alamos, NM); Foreman, Trudi M. (Los Alamos, NM); Hanners, John L. (Los Alamos, NM)

2000-01-01T23:59:59.000Z

154

Catalysis Center for Energy Innovation (CCEI): YouTube Channel for this Energy Frontier Research Center (EFRC)  

DOE Data Explorer (OSTI)

CCEI is among the 46 Energy Frontier Research Centers (EFRCs) funded by DOE and was established in the spring of 2009. CCEI is one of the very few externally funded centers on heterogeneous catalysis. CCEI leverages federal funding to enable technology transfer and commercialization through an industrial consortium. The center builds upon the long tradition of the Center for Catalytic Science and Technology (CCST) at the University of Delaware and extends its expertise within a virtual center among multiple partner institutions and national labs (University of Pennsylvania, Caltech, University of Minnesota, University of Massachusetts, Lehigh University, Brookhaven National Labs, University of North Carolina, and University of Southern California). CCEI provides an integrated approach to solving scientific and engineering problems that span across scales and disciplines, ranging from synthesis and characterization of novel catalysts to development and application of a multiscale modeling toolbox to reaction and reactor evaluation to technology transfer.[Copied with editing from http://www.youtube.com/catalysiscenter#p/u

155

Homogeneity Analysis of Event History Data  

E-Print Network (OSTI)

phrases. Correspondence Analysis, Event History Data. JAN DEHOMOGENEITY ANALYSIS OF EVENT HISTORY DATA JAN DE LEEUW,Kreft, Homogeneity Analysis of Event History Data. Methods

Leeuw, Jan de; Heijden, Peter van der; Kreft, Ita

2010-01-01T23:59:59.000Z

156

Homogeneity Analysis of Event History Data  

E-Print Network (OSTI)

phrases. Correspondence Analysis, Event History Data. JAN DEHOMOGENEITY ANALYSIS OF EVENT HISTORY DATA JAN DE LEEUW,Kreft, Homogeneity Analysis of Event History Data. Methods

Jan de Leeuw; Peter van der Heijden; Ita Kreft

2011-01-01T23:59:59.000Z

157

AQUEOUS HOMOGENEOUS REACTORTECHNICAL PANEL REPORT  

Science Conference Proceedings (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

158

Pacific Northwest National Laboratory Catalysis Highlights for FY2007  

DOE Green Energy (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

Analysis and optimization of gyrokinetic toroidal simulations on homogenous and heterogenous platforms  

Science Conference Proceedings (OSTI)

The Gyrokinetic Toroidal Code (GTC) uses the particle-in-cell method to efficiently simulate plasma microturbulence. This work presents novel analysis and optimization techniques to enhance the performance of GTC on large-scale machines. We introduce ... Keywords: GPU programming, Particle-in-cell, hybrid programming, memory-centric multi-core tuning, multi-core optimization

Khaled Z Ibrahim, Kamesh Madduri, Samuel Williams, Bei Wang, Stephane Ethier, Leonid Oliker

2013-11-01T23:59:59.000Z

160

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

E-Print Network (OSTI)

Full Journal Title:Journal of Chemical Physics, 2009, 130,FIELD Full Journal Title:Chemical Physics Letters, 2002,Journal Title:Journal of Chemical Physics, 1983, 78, 688. D.

Kaiser, Ralf I.

2010-01-01T23:59:59.000Z

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.


161

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

E-Print Network (OSTI)

and irradiated propane ice gas phase sublimation profiles.to crystalline phase ethane ices. 111 Having discussed theethane ice converts to an amorphous phase over the

Kaiser, Ralf I.

2010-01-01T23:59:59.000Z

162

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

E-Print Network (OSTI)

induced formation of n-butane. Although absorption bandsthe fundamental modes of the n-butane species in the presentspectra indicates that n-butane was not formed under the

Kaiser, Ralf I.

2010-01-01T23:59:59.000Z

163

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

164

Homogenization of Temperature Series via Pairwise Comparisons  

Science Conference Proceedings (OSTI)

An automated homogenization algorithm based on the pairwise comparison of monthly temperature series is described. The algorithm works by forming pairwise difference series between serial monthly temperature values from a network of observing ...

Matthew J. Menne; Claude N. Williams Jr.

2009-04-01T23:59:59.000Z

165

The ??? Amplitude in an External Homogeneous Electromagnetic  

E-Print Network (OSTI)

Neutrino-photon interactions in the presence of an external homogeneous constant electromagnetic field are studied. The ??? amplitude is calculated in an electromagnetic field of the general type, when the two field invariants are nonzero.

R. Shaisultanov

2000-01-01T23:59:59.000Z

166

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

167

Homogenization of Daily Temperatures over Canada  

Science Conference Proceedings (OSTI)

A method to homogenize daily maximum and minimum temperatures over Canada is presented. The procedure is based on previously defined monthly adjustments derived from step changes identified in annual Canadian temperature series. Daily ...

Lucie A. Vincent; X. Zhang; B. R. Bonsal; W. D. Hogg

2002-06-01T23:59:59.000Z

168

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

E-Print Network (OSTI)

Fundamental studies of heterogeneous catalysis were performed and presented in this dissertation to gain a better understanding of heterogeneous catalytic reactions at a molecular level. Surface science techniques were employed in achieving the goal. Low energy ion scattering spectroscopy (LEISS) is the main surface science technique which will be used in all the studies discussed throughout this dissertation. The main objectives of LEISS measurements are to: 1) obtain the information of surface composition of heterogeneous catalysts from the topmost layer; 2) observe the effects of reaction conditions on the surface composition of heterogeneous catalysts. The surface composition and morphology of Au-Pd clusters bimetallic model catalysts supported on SiO2 were characterized using LEISS, infrared reflection absorption spectroscopy (IRAS), and temperature programmed desorption (TPD). It is observed that relative to the bulk, the surface of the clusters is enriched in Au. Ethylene adsorption and dehydrogenation show a clear structure-reactivity correlation with respect to the structure/composition of these Au-Pd model catalysts. Fundamental studies of heterogeneous catalysis were performed and presented in this dissertation to gain a better understanding of heterogeneous catalytic reactions at a molecular level. Surface science techniques were employed in achieving the goal. Low energy ion scattering spectroscopy (LEISS) is the main surface science technique which will be used in all the studies discussed throughout this dissertation. The main objectives of LEISS measurements are to: 1) obtain the information of surface composition of heterogeneous catalysts from the topmost layer; 2) observe the effects of reaction conditions on the surface composition of heterogeneous catalysts. The surface composition and morphology of Au-Pd clusters bimetallic model catalysts supported on SiO2 were characterized using LEISS, infrared reflection absorption spectroscopy (IRAS), and temperature programmed desorption (TPD). It is observed that relative to the bulk, the surface of the clusters is enriched in Au. Ethylene adsorption and dehydrogenation show a clear structure-reactivity correlation with respect to the structure/composition of these Au-Pd model catalysts.

Axnanda, Stephanus R.

2009-12-01T23:59:59.000Z

169

Hydrogen catalysis and scavenging action of Pd-POSS nanoparticles  

DOE Green Energy (OSTI)

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

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

2007-02-01T23:59:59.000Z

170

Inorganic Chemistry in Hydrogen Storage and Biomass Catalysis  

DOE Green Energy (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

171

Fuels and energy for the future: The role of catalysis  

SciTech Connect

There are many reasons to decrease the dependency on oil and to increase the use of other energy sources than fossil fuels. The wish for energy security is balanced by a wish for sustainable growth. Catalysis plays an important role in creating new routes and flexibility in the network of energy sources, energy carriers, and energy conversion. The process technologies resemble those applied in the large scale manufacture of commodities. This is illustrated by examples from refinery fuels, synfuels, and hydrogen and the future role of fossil fuels is discussed.

Rostrup-Nielsen, J.R.; Nielsen, R. [Haldor Topsoe Research Labs., Lyngby (Denmark)

2004-07-01T23:59:59.000Z

172

Argonne Chemical Sciences & Engineering - Catalysis & Energy Conversion -  

NLE Websites -- All DOE Office Websites (Extended Search)

Ceramic Electrochemistry Ceramic Electrochemistry * Members * Contact * Publications * Overview * Solid Oxide Fuel Cells * Steam Electrolysis Catalysis & Energy Conversion Home Ceramic Electrochemistry Dave Carter and solid oxide fuel cell Materials scientist John David Carter prepares a solid oxide electrochemical cell for high temperature testing. Research activities in the Ceramic Electrochemistry Group are focused on the development of ceramic-based electrochemical devices and components, such as Solid Oxide Fuel Cells (SOFC) and High Temperature Steam Electrolyzers (HTSE). This extends to materials synthesis, fabrication, and characterization. Solid Oxide Fuel Cell Research As part of the Solid State Energy Conversion Alliance (SECA) Core Technology Program, the goal of this research is the development of solid

173

Modeling complex heterogeneous objects with non-manifold heterogeneous cells  

Science Conference Proceedings (OSTI)

This paper presents a new approach to model complex heterogeneous objects with simultaneous geometry intricacies as well as complex material distributions. Different from most of the existing approaches, which utilize manifold B-Rep and the assembly ... Keywords: Attribute based reasoning, Boolean operation, Cellular model, Heterogeneous material, Non-manifold

X. Y. Kou; S. T. Tan; W. S. Sze

2006-05-01T23:59:59.000Z

174

Prolonging the lifetime of wireless sensor networks using multi-level clustering and heterogeneity  

Science Conference Proceedings (OSTI)

Clustering in wireless sensor networks (WSNs) is an important technique to prolong lifetime of a WSN. This paper proposes energy efficient multi-level clustering scheme called Power Aware Multi-level Clustering (PAMC) for homogeneous wireless sensor ... Keywords: algorithm, energy efficiency, heterogeneity, multi-level clustering, wireless sensor networks

Surender Soni; Vivek Katiyar

2011-02-01T23:59:59.000Z

175

Materials Design and Discovery: Catalysis and Electrical Energy Storage  

NLE Websites -- All DOE Office Websites (Extended Search)

and Discovery: Catalysis and Discovery: Catalysis and Electrical Energy Storage Presenter: N ichols A . R omero, A LCF ESP p ost---doc: Anouar B enali, A LCF PI: L arry C urAss, A NL M SD a nd C NM Comments from a reviewer on "Material Design and Discovery" from a proposal § How c ould t his m achine w ith t hese p rograms b e u sed t o d esign a n ew s olar c ell? Or a n ew c ure f or A IDS? O r a n ew h igh---T s uperconductor? T his i s n ot i ntended a s a trivial q uesAon. T he p resent m ethod o f D ISCOVERY r elies o n t he t rained h uman mind ( insight) a nd e xperiment ( serendipity). C omputaAonal s cience s o f ar h as n ot delivered a ny n ew d iscoveries b ecause i t l acks t he p ossibility o f s erendipity. T he greatest s uccess o f c omputaAonal c hemistry h as b een i mproved i nsight i nto t he way m aterial b ehaves

176

Fundamental solutions of homogeneous elliptic differential operators  

E-Print Network (OSTI)

We compute fundamental solutions of homogeneous elliptic differential operators, with constant coefficients, on $\\mathbb{R}^n$ by mean of analytic continuation of distributions. The result obtained is valid in any dimension, for any degree and can be extended to pseudodifferential operators of the same type.

Brice Camus

2005-10-31T23:59:59.000Z

177

Coherence delay augmented laser beam homogenizer  

DOE Patents (OSTI)

It is an object of the present invention to provide an apparatus that can reduce the apparent coherence length of a laser beam so the beam can be used with an inexpensive homogenizer to produce an output beam with a uniform spatial intensity across its entire cross section. It is a further object of the invention to provide an improved homogenizer with a variable aperture size that is simple and easily made. It is still an additional object of the invention to provide an improved liquid filled homogenizer utilizing total internal reflection for improved efficiency. These, and other objects of the invention are realized by using a ``coherence delay line,`` according to the present invention, in series between a laser and a homogenizer. The coherence delay line is an optical ``line`` that comprises two mirrors, one partially reflecting, and one totally reflecting, arranged so that light incident from the laser first strikes the partially reflecting mirror. A portion of the beam passes through, and a portion is reflected back to the totally reflecting mirror.

Rasmussen, P.; Bernhardt, A.

1991-12-31T23:59:59.000Z

178

Microgrids and Heterogeneous Security, Quality, Reliability, and Availability  

E-Print Network (OSTI)

Abstract--This paper describes two stylized alternative visions in popular currency 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. Economic perspectives are presented on both the choice of homogeneous universal power quality upstream in the electricity supply, and also on the extremely heterogeneous requirements of end-use loads. 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. • Index Terms--cogeneration, dispersed storage and generation, power quality, power system economics I.

C. Marnay

2007-01-01T23:59:59.000Z

179

The Effect of Heterogeneity on Matrix Acidizing of Carbonate Rocks  

E-Print Network (OSTI)

In matrix acidizing, the goal is to dissolve minerals in the rock to increase well productivity. This is accomplished by injecting an application-specific solution of acid into the formation at a pressure between the pore pressure and fracture pressure. A hydrochloric acid solution is used in carbonate reservoirs, which actually dissolves the calcite rock matrix in the form of conductive channels called wormholes. These wormholes propagate from the wellbore out into the reservoir, bypassing the damaged zone. In matrix acidizing of carbonates, there are four parameters that affect performance: the concentration of calcite present, injection rate of the acid, reaction type, and heterogeneity. Of these parameters, this paper will focus on how rock heterogeneity affects performance. To do this, a coreflood and acidizing apparatus was used to acidize heterogeneous limestone core samples. Rock characterizations and volumetric measurements were considered with the results from these experiments, which made it possible to correlate and quantify the results with rock and volume parameters. It was found that the core samples with more and larger heterogeneities generally required less acid (measured in pore volumes) to achieve breakthrough, that is, a wormhole created axially from one end of the core to the other. This value for pore volumes to breakthrough was one to two orders of magnitude less than more homogeneous samples. The general procedure and best practices for acidizing the core samples is also detailed in this thesis. This procedure was followed for preparation, coreflooding, and acidizing for all core samples.

Keys, Ryan S.

2009-12-01T23:59:59.000Z

180

Microgrids and Heterogeneous Security, Quality, Reliability, andAvailability  

Science Conference Proceedings (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

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

Argonne Chemical Sciences & Engineering - Catalysis & Energy Conversion  

NLE Websites -- All DOE Office Websites (Extended Search)

Hydrogen and Fuel Cell Materials Hydrogen and Fuel Cell Materials * Members * Contact * Publications * Overview * Alternative Electrocatalysts * Electrocatalyst Durability * Hydrogen Storage * Electrocatalyst Degradation Catalysis & Energy Conversion Home Hydrogen and Fuel Cell Materials Polymer electrolyte fuel cell (PEFC) systems are promising alternatives to conventional power systems for transportation, portable, and stationary applications due to their high efficiency of converting fuel to electricity, low emissions, and low operating temperatures. Three major issues for PEFC systems, especially for portable and transportation use, are cost, lifetime, and fuel storage, with the fuel of choice being hydrogen. Argonne's Hydrogen and Fuel Cell Materials group has active research projects in these three areas, to enable the use of this promising technology in a variety of applications.

182

Key Accomplishments @ Catalysis: Reactivity and Structure Group | Chemistry  

NLE Websites -- All DOE Office Websites (Extended Search)

Recent Key Accomplishments Recent Key Accomplishments WGS: Importance of the Metal-Oxide Interface in Catalysis: In Situ Studies of the Water-Gas Shift Reaction by Ambient-Pressure X-ray Photoelectron Spectroscopy A New Type of Strong Metal-Support Interaction and the Production of H-2 through the Transformation of Water on Pt/CeO2(111) and Pt/CeOx/TiO2(110) Catalysts In situ studies of CeO2-supported Pt, Ru, and Pt-Ru alloy catalysts for the water-gas shift reaction: Active phases and reaction intermediates In situ/operando studies for the production of hydrogen through the water-gas shift on metal oxide catalysts Mechanistic understanding of WGS catalysts from first principles: Au(111) Supported Oxide Nanoparticles Theoretical catalyst optimization of WGS catalysts: Cu(111) supported oxide nanostructures

183

Argonne Chemical Sciences & Engineering - Catalysis & Energy Conversion -  

NLE Websites -- All DOE Office Websites (Extended Search)

Atom-Efficient Chemical Transformations Atom-Efficient Chemical Transformations iact logo Argonne National Laboratory along with its academic partners has established an Energy Frontier Research Center, the Institute for Atom-efficient Chemical Transformations (IACT) whose focus is to advance the science of catalysis for the efficient conversion of energy resources into usable forms. IACT is one of 46 Energy Frontier Research Centers that DOE has established in the United States. IACT is a partnership among world-class scientists at Argonne National Laboratory, Northwestern University, Purdue University, University of Wisconsin-Madison, and Brookhaven National Laboratory. Using a multidisciplinary approach involving integrated catalyst synthesis, advanced characterization, catalytic experimentation, and computation, IACT is addressing key

184

Blue Ruthenium Dimer Catalysis for Hydrogen Generation | Advanced Photon  

NLE Websites -- All DOE Office Websites (Extended Search)

A High-Pressure Nano-imaging Breakthrough A High-Pressure Nano-imaging Breakthrough Protein Structure Could Lead to Better Treatments for HIV, Early Aging The Superpower behind Iron Oxyfluoride Battery Electrodes Watching a Protein as it Functions Shedding Light on Chemistry with a Biological Twist Science Highlights Archives: 2013 | 2012 | 2011 | 2010 2009 | 2008 | 2007 | 2006 2005 | 2004 | 2003 | 2002 2001 | 2000 | 1998 | Subscribe to APS Science Highlights rss feed Blue Ruthenium Dimer Catalysis for Hydrogen Generation APRIL 15, 2013 Bookmark and Share Key intermediates in the water oxidation catalytic cycle of the blue dimer characterized by x-ray spectroscopy. Optimization of the reactivity toward water (purple arrow) and oxidation of the resulting peroxo-intermediate (blue arrow) are needed for improved catalytic activity.

185

Tandem Catalysis in Nanocrystal Interfaces | Department of Energy  

Energy.gov (U.S. Department of Energy (DOE)) Indexed Site

Interfaces Interfaces Tandem Catalysis in Nanocrystal Interfaces July 18, 2011 - 2:45pm View(active tab) Edit Workflow Addthis A unique new bilayer nanocatalyst system. | Image courtesy of Yang group A unique new bilayer nanocatalyst system. | Image courtesy of Yang group What does this mean for me? A prime example of these applications is artificial photosynthesis -- the effort to capture energy from the sun and transform it into electricity or chemical fuels. Catalysts (substances that speed up the rates of chemical reactions without themselves being chemically changed) are used to initiate virtually every industrial manufacturing process that involves chemistry. With the advent of nano-sized catalysts, metal and metal oxide catalysts have surged in importance. Recently, researchers at the Department's Lawrence Berkeley National

186

Session Overview: Heterogeneous Combustion Randall E. Winans...  

NLE Websites -- All DOE Office Websites (Extended Search)

Heterogeneous Combustion Randall E. Winans, Session Chair X-ray Science Division, Advanced Photon Source, Argonne National Laboratory, Argonne, IL 60439, USA Heterogeneous...

187

The outer-coordination sphere: incorporating amino acids and peptides as ligands for homogeneous catalysts to mimic enzyme function  

SciTech Connect

Great progress has been achieved in the field of homogeneous transition metal-based catalysis, however, as a general rule these solution based catalysts are still easily outperformed, both in terms of rates and selectivity, by their analogous enzyme counterparts, including structural mimics of the active site. This observation suggests that the features of the enzyme beyond the active site, i.e. the outer-coordination sphere, are important for their exceptional function. Directly mimicking the outer-coordination sphere requires the incorporation of amino acids and peptides as ligands for homogeneous catalysts. This effort has been attempted for many homogeneous catalysts which span the manifold of catalytic reactions and often require careful thought regarding solvent type, pH and characterization to avoid unwanted side reactions or catalyst decomposition. This article reviews the current capability of synthesizing and characterizing this often difficult category of metal-based catalysts. This work was funded by the DOE Office of Science Early Career Research Program through the Office of Basic Energy Sciences. Pacific Northwest National Laboratory is operated by Battelle for the U.S. Department of Energy.

Shaw, Wendy J.

2012-10-09T23:59:59.000Z

188

Feasibility studies of a fuel cell for cogeneration of homogeneously catalyzed acetaldehyde and electricity from ethanol  

Science Conference Proceedings (OSTI)

The development and feasibility of a novel fuel cell for simultaneously generating electricity and homogeneously catalyzed acetaldehyde from ethanol are reported. The fuel cell is based on the supported molten-salt electrocatalysis technique that allows use of homogeneous (liquid-phase) catalysts in fuel cells for the first time. The electrocatalytic reaction combines the chemistry of the Wacker process conventionally used for acetaldehyde production from the partial oxidation of ethylene and that of the Veba-Chemie method. Nafion membranes impregnated with different electrolytic materials were used in the fuel cell as electrolytes to allow operation at reaction temperatures up to 165 C. Results obtained are comparable to those reported in the literature on partial oxidation of ethylene to acetaldehyde in a fuel cell based on conventional heterogeneous electrocatalysts.

Malhotra, S.; Datta, R. [Univ. of Iowa, Iowa City, IA (United States). Dept. of Chemical and Biochemical Engineering

1996-10-01T23:59:59.000Z

189

Manticore: a heterogeneous parallel language  

Science Conference Proceedings (OSTI)

The Manticore project is an effort to design and implement a new functional language for parallel programming. Unlike many earlier parallel languages, Manticore is a heterogeneous language that supports parallelism at multiple levels. Specifically, ...

Matthew Fluet; Mike Rainey; John Reppy; Adam Shaw; Yingqi Xiao

2007-01-01T23:59:59.000Z

190

Composing heterogeneous software with style  

Science Conference Proceedings (OSTI)

Tools for composing software impose homogeneity requirements on what is composed-that modules must share a language, target the same libraries, or share other conventions. This inhibits cross-language and cross-infrastructure composition. We observe ...

Stephen Kell

2011-07-01T23:59:59.000Z

191

TESTING HOMOGENEITY WITH GALAXY STAR FORMATION HISTORIES  

Science Conference Proceedings (OSTI)

Observationally confirming spatial homogeneity on sufficiently large cosmological scales is of importance to test one of the underpinning assumptions of cosmology, and is also imperative for correctly interpreting dark energy. A challenging aspect of this is that homogeneity must be probed inside our past light cone, while observations take place on the light cone. The star formation history (SFH) in the galaxy fossil record provides a novel way to do this. We calculate the SFH of stacked luminous red galaxy (LRG) spectra obtained from the Sloan Digital Sky Survey. We divide the LRG sample into 12 equal-area contiguous sky patches and 10 redshift slices (0.2 < z < 0.5), which correspond to 120 blocks of volume {approx}0.04 Gpc{sup 3}. Using the SFH in a time period that samples the history of the universe between look-back times 11.5 and 13.4 Gyr as a proxy for homogeneity, we calculate the posterior distribution for the excess large-scale variance due to inhomogeneity, and find that the most likely solution is no extra variance at all. At 95% credibility, there is no evidence of deviations larger than 5.8%.

Hoyle, Ben; Jimenez, Raul [Institut de Ciences del Cosmos (ICC), Universitat de Barcelona (IEEC-UB), Marti i Franques 1, E-08024 Barcelona (Spain); Tojeiro, Rita; Maartens, Roy [Institute of Cosmology and Gravitation, University of Portsmouth, Dennis Sciama Building, Portsmouth PO1 3FX (United Kingdom); Heavens, Alan [Imperial Centre for Inference and Cosmology, Astrophysics Group, Imperial College London, Blackett Laboratory, Prince Consort Road, London SW7 2AZ (United Kingdom); Clarkson, Chris [Astrophysics, Cosmology and Gravity Centre, and Department of Mathematics and Applied Mathematics, University of Cape Town, Rondebosch 7701 (South Africa)

2013-01-01T23:59:59.000Z

192

Substrate inhibition in the heterogeneous catalyzed aldol condensation: A mechanistic study of supported organocatalysts  

SciTech Connect

In this study, we demonstrate how materials science can be combined with the established methods of organic chemistry to find mechanistic bottlenecks and redesign heterogeneous catalysts for improved performance. By using solid-state NMR, infrared spectroscopy, surface and kinetic analysis, we prove the existence of a substrate inhibition in the aldol condensation catalyzed by heterogeneous amines. We show that modifying the structure of the supported amines according to the proposed mechanism dramatically enhances the activity of the heterogeneous catalyst. We also provide evidence that the reaction benefits significantly from the surface chemistry of the silica support, which plays the role of a co-catalyst, giving activities up to two orders of magnitude larger than those of homogeneous amines. This study confirms that the optimization of a heterogeneous catalyst depends as much on obtaining organic mechanistic information as it does on controlling the structure of the support.

Kandel, Kapil; Althaus, Stacey M.; Peeraphatdit, Chorthip; Kobayashi, Takeshi; Trewyn, Brian G.; Pruski, Marek; Slowing, Igor I.

2012-05-23T23:59:59.000Z

193

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.

194

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

SciTech Connect

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

195

Density Functional Theory in Surface Chemistry and Catalysis  

SciTech Connect

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

196

NOX REDUCTION FOR LEAN EXHAUST USING PLASMA ASSISTED CATALYSIS  

DOE Green Energy (OSTI)

Currently CARB estimates on road diesel vehicles contribute 50% of the NOX and 78% of the particulates being discharged from mobile sources. Diesel emissions obviously must be reduced if future air quality targets are to be met. A critical technological barrier exists because there are no commercial technologies available, which can reduce NOX from diesel (lean), exhaust containing 5-15% O2 concentration. One promising approach to reducing NOX and particulates from diesel exhaust is to use a combination of plasma with catalyst. Plasma can be generated thermally or non-thermally. Thermal plasma is formed by heating the system to an exceedingly high temperature (>2000 C). High temperature requirements for plasma makes thermal plasma inefficient and requires skillful thermal management and hence is considered impractical for mobile applications. Non-thermal plasma directs electrical energy into the creation of free electrons, which in turn react with gaseous species thus creating plasma. A combination of non-thermal plasma with catalysts can be referred to Plasma Assisted Catalysts or PAC. PAC technology has been demonstrated in stationary sources where non-thermal plasma catalysis is carried out in presence of NH3 as a reductant. In stationary applications NO is oxidized to HNO3 and then into ammonium nitrate where it is condensed and removed. This approach is impractical for mobile application because of the ammonia requirement and the ultimate mechanism by which NOX is removed. However, if a suitable catalyst can be found which can use onboard fuel as reductant then the technology holds a considerable promise. NOX REDUCTION FOR LEAN EXHAUST USING PLASMA ASSISTED CATALYSIS Ralph Slone, B. Bhatt and Victor Puchkarev NOXTECH INC. In addition to the development of an effective catalyst, a non-thermal plasma reactor needs be scaled and demonstrated along with a reliable and cost effective plasma power source and onboard HC source needs to be proven. Under the work sponsored by DOE and SCAQMD Noxtech is developing a cost effective and reliable PAC system for mobile applications. The goal of the program is to develop a suitable catalyst with the ability to remove high levels of NOx at reasonable space velocities. This new catalyst will then be used to scale the technology to treat exhaust from 80Hp engine and eventually to demonstrate the technology on 200 and 400 Hp engine applications. Using the 2004 EPA proposed regulation as a standard, it is clear in order for PAC system to be commercially viable it needs to remove NOX by 70% or better. It is further assumed from past experience that 30,000 HR-1 space velocities are necessary to ensure a good compact design.

Bhatt, B.

2000-08-20T23:59:59.000Z

197

Consumption processes and positively homogeneous projection properties  

E-Print Network (OSTI)

We constructively prove the existence of time-discrete consumption processes for stochastic money accounts that fulfill a pre-specified positively homogeneous projection property (PHPP) and let the account always be positive and exactly zero at the end. One possible example is consumption rates forming a martingale under the above restrictions. For finite spaces, it is shown that any strictly positive consumption strategy with restrictions as above possesses at least one corresponding PHPP and could be constructed from it. We also consider numeric examples under time-discrete and -continuous account processes, cases with infinite time horizons and applications to income drawdown and bonus theory.

Fischer, Tom

2007-01-01T23:59:59.000Z

198

Consumption processes and positively homogeneous projection properties  

E-Print Network (OSTI)

We constructively prove the existence of time-discrete consumption processes for stochastic money accounts that fulfill a pre-specified positively homogeneous projection property (PHPP) and let the account always be positive and exactly zero at the end. One possible example is consumption rates forming a martingale under the above restrictions. For finite spaces, it is shown that any strictly positive consumption strategy with restrictions as above possesses at least one corresponding PHPP and could be constructed from it. We also consider numeric examples under time-discrete and-continuous account processes, cases with infinite time horizons and applications to income drawdown and bonus theory.

Tom Fischer

2008-01-01T23:59:59.000Z

199

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

200

Lean NOx catalysis for gasoline fueled European cars  

SciTech Connect

There is increasing interest in operating gasoline fueled passenger cars lean of the stoichiometric air/fuel (A/F) ratio to improve fuel economy. These types of engines will operate at lean A/F ratios while cruising at partial load, and return to stoichiometric or even rich conditions when more power is required. The challenge for the engine and catalyst manufacturer is to develop a system which will combine the high activity rates of a state-of-the-art three-way catalyst (TWC) with the ability to reduce nitrogen oxides (NOx) in the presence of excess oxygen. The objective is to achieve the future legislative limits (EURO III/IV) in the European Union. Recent developments in automotive pollution control catalysis show that the use of NOx adsorption materials is a suitable way to reduce NOx emissions of gasoline-fueled lean-burn engines. However, the primary task for the implementation of this technology in the European market will be to improve the catalyst`s high-temperature stability and to decrease its susceptibility to sulfur poisoning. Outlined here are results of a recent R and D program to achieve NOx reduction under lean-burn gasoline engine conditions. Model gas test results as well as engine bench data are used for discussion of the parameters which control NOx adsorption efficiency under various conditions.

NONE

1997-02-01T23:59:59.000Z

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.


201

Design of Catalytic Materials for Plasma Assisted Catalysis System  

DOE Green Energy (OSTI)

In recent years, the Plasma Assisted Catalysis (PAC) approach for controlling NOx and/or particulate emissions from mobile diesel engines has received a significant amount of attention from researchers. Substantial work has been performed by various researchers to develop an understanding of the reaction mechanisms in a plasma reactor in conjunction with conventional lean-NOx catalyst materials. However, less effort has been devoted to systematically investigating new catalyst materials specifically designed for application in the PAC system. Since it is believed that plasma produces a unique environment for a catalyst bed (i.e. oxidation of NO to NO2 and partial oxidation/reforming of hydrocarbon reductants in the exhaust), new catalytic materials that take advantage of the plasma reactor conditions need to be studied. Optimum catalyst materials will be required in order to develop a PAC system that achieves maximum deNOx performance over the wide range of operating conditions in which the system will be required to operate for application on heavy duty diesel engines. This presentation discusses the issues involved in designing catalytic materials for achieving high NOx conversion in a laboratory test PAC system, and what is required to improve the catalyst materials further for application in an on-engine environment.

Park, Paul W.

2000-08-20T23:59:59.000Z

202

Argonne Chemical Sciences & Engineering - Publications - Catalysis and  

NLE Websites -- All DOE Office Websites (Extended Search)

Fuel Cell Engineering Fuel Cell Engineering A H. Adachi, S. Ahmed, S. H. D. Lee, D. Papadias, R. K. Ahluwalia, J. C. Bendert, S. A. Kanner, and Y. Yamazaki, "A Natural-Gas Fuel Processor for a Residential Fuel Cell System," Journal of Power Sources, accepted for publication (2009) S. Ahmed, "Renewable Power Sources," (invited talk), University of Houston, Houston, TX, March 22-23, 2012. S. Ahmed, "Fuel Cell Based Combined Heat and Power for Small Systems (1-100 kW)," (invited talk), University of Houston, Houston, TX, March 22-23, 2012. S. Ahmed, R. Ahluwalia, S. H. D. Lee and S. Lottes, "A Gasoline Fuel Processor Designed to Study Quick-Start Performance," Journal of Power Sources 154(1), 214-222 (2006) C S. Y. Choung, M. Ferrandon, and T. Krause, "Pt-Re Bimetallic Supported on CeO2-ZrO2 Mixed Oxides as Water-Gas Shift Catalysts," Catalysis Today 99, 257-262 (2005)

203

Homogeneous ice nucleation at moderate supercooling from molecular simulation  

E-Print Network (OSTI)

Among all the freezing transitions, that of water into ice is probably the most relevant to biology, physics, geology or atmospheric science. In this work we investigate homogeneous ice nucleation by means of computer simulations. We evaluate the size of the critical cluster and the nucleation rate for temperatures ranging between 15K and 35K below melting. We use the TIP4P/2005 and the TIP4P/Ice water models. Both give similar results when compared at the same temperature difference with the model's melting temperature. The size of the critical cluster varies from $\\sim$8000 molecules (radius$ = 4$nm) at 15K below melting to $\\sim$600 molecules (radius$ = 1.7$nm) at 35K below melting. We use Classical Nucleation Theory (CNT) to estimate the ice-water interfacial free energy and the nucleation free energy barrier. We obtain an interfacial free energy of 29(3)mN/m from an extrapolation of our results to the melting temperature. This value is in good agreement both with experimental measurements and with previous estimates from computer simulations of TIP4P-like models. Moreover, we obtain estimates of the nucleation rate from simulations of the critical cluster at the barrier top. The values we get for both models agree within statistical error with experimental measurements. At temperatures higher than 20K below melting we get nucleation rates slower than the appearance of a critical cluster in all the water of the hydrosphere in the age of the universe. Therefore, our simulations predict that water freezing above this temperature must necessarily be heterogeneous.

E. Sanz; C. Vega; J. R. Espinosa; R. Caballero-Bernal; J. L. F. Abascal; C. Valeriani

2013-12-03T23:59:59.000Z

204

Computationally Optimized Homogenization Heat Treatment of Metal Alloys  

? A computational approach has been developed to improve the homogenization heat treatment of solid substitutional alloys. The method utilizes ...

205

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

E-Print Network (OSTI)

The research in this dissertation examines the chemistry and applications of dendrimers in homogeneous catalysis. We examined interactions between dendrimers and charged probe molecules, prepared dendrimer-encapsulated metal nanoparticles in organic solvents, studied size-selectivity of dendrimer-encapsulted catalysts, and designed molecular rulers as in-situ probes to measure the location of dendrimer-encapsulted metal nanoparticles. The intrinsic proton binding constant and a constant that characterizes the strength of electrostatic interactions among occupied binding sites in poly(amidoamine) (PAMAM) dendrimers have been obtained by studying the effect of solution pH on the protonation of the dendrimers. The significant finding is that these two factors are greatly modulated by the unique and hydrophobic microenvironment in the dendrimer interior. Hydrophilic poly(propylene imine) (PPI) dendrimers were modified with various hydrophobic alkyl chains through an amide linkage and were then used as templates for preparing intradendrimer copper nanoclusters. The main driving force for encapsulating metal-ions was found to be the differences in metal-ion solubility between the solvent and the interior of the dendrimer. Nanometer-sized metal particles are synthesized and encapsulated into the interior of dendrimers by first mixing together the dendrimer and metal ion solution and then reducing the composite chemically, and the resulting dendrimer-encapsulated metal nanoparticles can then be used as catalysts. By controlling the packing density on the dendrimer periphery using either different dendrimer generations or dendrimer surface functionalities, it is possible to control access of substrates to the encapsulated catalytic nanoparticle. Molecular rulers consisting of a large molecular "stopper", a reactive probe and a linker were designed as in-situ probes for determining the average distance between the surface of dendrimer-encapsulated palladium nanoparticles and the periphery of their fourth-generation, hydroxyl-terminated PAMAM dendrimer hosts. By doing so, we avoid having to make assumptions about the nanoparticle size and shape. The results suggest that the surface of the encapsulated nanoparticle is situated 0.7 ± 0.2 nm from the surface of the dendrimer.

Niu, Yanhui

2003-05-01T23:59:59.000Z

206

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

207

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

208

The Computational Modeling of Alloys:From ab initio and thermodynamics to heterogeneous precipitation.  

SciTech Connect

In this lecture we presented a methodology to obtain free energies from empirical potentials and applied it to the study of the phase diagram of FeCr. Subsequently, we used Metropolis Monte Carlo to analyze homogeneous and heterogeneous precipitation of the Cr rich solid solution {alpha}{prime}. These examples are part of our work in the area of steels for nuclear applications and can be found in several publications of our group cited as References.

Caro, A

2007-10-09T23:59:59.000Z

209

Geek-Up[3.11.2011]: Energy Efficiency, Catalysis and Open Source Tools |  

Energy.gov (U.S. Department of Energy (DOE)) Indexed Site

1.2011]: Energy Efficiency, Catalysis and Open Source 1.2011]: Energy Efficiency, Catalysis and Open Source Tools Geek-Up[3.11.2011]: Energy Efficiency, Catalysis and Open Source Tools March 11, 2011 - 4:37pm Addthis L. Keith Woo | Photo courtesy of Ames National Laboratory L. Keith Woo | Photo courtesy of Ames National Laboratory Niketa Kumar Niketa Kumar Public Affairs Specialist, Office of Public Affairs Ames Laboratory researcher and Iowa State University professor L. Keith Woo is on the search for catalysts that lead to more efficient, safer and cleaner chemical reactions that work at lower pressures and temperatures and create less waste. In one project, Dr. Woo is working to understand the chemistry behind fast pyrolysis for creating bio-oil from biomass. Fast pyrolysis quickly heats up biomass (such as corn stalks and leaves) in the absence of oxygen to

210

Supported organometallic complexes: Surface chemistry, spectroscopy, and catalysis  

SciTech Connect

The long-range goal of this project is to elucidate and understand the surface chemistry and catalytic properties of well-defined, highly-reactive organometallic molecules (principally based upon abundant actinide, lanthanide, and early transition elements) adsorbed on metal oxides and halides. The nature of the adsorbed species is probed by a battery of chemical and physicochemical techniques, to understand the nature of the molecular-surface coordination chemistry and how this can give rise to extremely high catalytic activity. A complementary objective is to delineate the scope and mechanisms of the heterogeneous catalytic reactions, as well as to relate them both conceptually and functionally to model systems generated in solution.

Marks, T.J.

1992-02-01T23:59:59.000Z

211

A CAD system for heterogeneous solid modelling  

Science Conference Proceedings (OSTI)

Objects that are made up of multiple materials and known as heterogeneous objects are now increasingly being used in engineering applications. The development of new fabrication methods like rapid prototyping (RP), calls for new techniques to ... Keywords: CAD model, STL file, functionally graded material, geometric information, heterogeneous models, heterogeneous solids, layered manufacturing, manufacturing strategy, material information, rapid prototyping, solid modelling

Puneet Tandon; Anuj Kant

2005-11-01T23:59:59.000Z

212

A CAD modeling system for heterogeneous object  

Science Conference Proceedings (OSTI)

A heterogeneous object (HO) modeling system independent of any commercial CAD packages is introduced in this paper. CAD models can be converted into 2D slices with heterogeneous material information for the fabrication of rapid prototyping technique. ... Keywords: CAD system, Heterogeneous object modeling, Volume graphics

Xiaojun Wu; Weijun Liu; Michael Yu Wang

2008-05-01T23:59:59.000Z

213

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

Science Conference Proceedings (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

214

Effects of capillary heterogeneity on vapor-liquid counterflow in porous media  

DOE Green Energy (OSTI)

Based on a continuum description, the effect of capillary heterogeneity, induced by variation in permeability, on the steady state, countercurrent, vapor-liquid flow in porous media is analyzed. It is shown that the heterogeneity acts as a body force, that may enhance or diminish gravity effects on heat pipes. Selection rules that determine the steady states reached in homogeneous, gravity-driven heat pipes are also formulated. It is shown that the ``infinite`` two-phase zone may terminate by a substantial change in the permeability somewhere in the medium. The two possible sequences, liquid - liquid dominated - dry, or liquid - vapor dominated - dry find applications in geothermal systems. Finally, it is shown that although weak heterogeneity affects only gravity controlled flows, stronger variations in permeability can give rise to significant capillary effects.

Stubos, A.K.; Satik, C.; Yortsos, Y.C.

1992-06-01T23:59:59.000Z

215

Effects of capillary heterogeneity on vapor-liquid counterflow in porous media  

DOE Green Energy (OSTI)

Based on a continuum description, the effect of capillary heterogeneity, induced by variation in permeability, on the steady state, countercurrent, vapor-liquid flow in porous media is analyzed. It is shown that the heterogeneity acts as a body force, that may enhance or diminish gravity effects on heat pipes. Selection rules that determine the steady states reached in homogeneous, gravity-driven heat pipes are also formulated. It is shown that the infinite'' two-phase zone may terminate by a substantial change in the permeability somewhere in the medium. The two possible sequences, liquid - liquid dominated - dry, or liquid - vapor dominated - dry find applications in geothermal systems. Finally, it is shown that although weak heterogeneity affects only gravity controlled flows, stronger variations in permeability can give rise to significant capillary effects.

Stubos, A.K.; Satik, C.; Yortsos, Y.C.

1992-06-01T23:59:59.000Z

216

Computationally Optimized Homogenization Heat Treatment of Metal Alloys  

NLE Websites -- All DOE Office Websites (Extended Search)

Computationally Optimized Homogenization Heat Computationally Optimized Homogenization Heat Treatment of Metal Alloys Contact NETL Technology Transfer Group techtransfer@netl.doe.gov May 2013 Significance * Reduction in energy consumption and carbon dioxide output due to shorter, more effective heat treatments * Substantially lower processing costs * Ability to optimize the mechanical properties of alloys for improved downstream performance * Adaptable to the constraints of individual production facilities and the level of homogenization desired Applications * Any solid substitutional alloy utilized in a

217

Computer Aided Design Modeling for Heterogeneous Objects  

E-Print Network (OSTI)

Heterogeneous object design is an active research area in recent years. The conventional CAD modeling approaches only provide geometry and topology of the object, but do not contain any information with regard to the materials of the object and so can not be used for the fabrication of heterogeneous objects (HO) through rapid prototyping. Current research focuses on computer-aided design issues in heterogeneous object design. A new CAD modeling approach is proposed to integrate the material information into geometric regions thus model the material distributions in the heterogeneous object. The gradient references are used to represent the complex geometry heterogeneous objects which have simultaneous geometry intricacies and accurate material distributions. The gradient references helps in flexible manipulability and control to heterogeneous objects, which guarantees the local control over gradient regions of developed heterogeneous objects. A systematic approach on data flow, processing, computer visualizat...

Gupta, Vikas; Tandon, Puneet

2010-01-01T23:59:59.000Z

218

Influence of Reinforcement Homogeneity on the Deformation and ...  

Science Conference Proceedings (OSTI)

... to determine deformation and fracture behavior for each condition of homogeneity via compression tests and chevron-notch short rod specimens, respectively.

219

FORCE-CLAMP SPECTROSCOPY DETECTS RESIDUE CO-EVOLUTION IN ENZYME CATALYSIS  

E-Print Network (OSTI)

distant correlated mutations in E. coli thioredoxin. Our findings show that evolutionary anti- correlated of distant residue co-evolution in enzyme catalysis. The acquisition of adequate activity by an enzyme,10). Analysis of co-evolving residues has been used to explore functional coupling in processes like protein

Fernandez, Julio M.

220

Catalysis looks to the future. Panel on new directions in catalytic science and technology  

Science Conference Proceedings (OSTI)

Catalysts play a vital role in providing society with fuels, commodity and fine chemicals, pharmaceuticals, and means for protecting the environment. To be useful, a good catalyst must have a high turnover frequency (activity), produce the right kind of product (selectivity), and have a long life (durability), all at an acceptable cost. Research in the field of catalysis provides the tools and understanding required to facilitate and accelerate the development of improved catalysts and to open opportunities for the discovery of new catalytic processes. The aim of this report is to identify the research opportunities and challenges for catalysis in the coming decades and to detail the resources necessary to ensure steady progress. Chapter 2 discusses opportunities for developing new catalysts to meet the demands of the chemical and fuel industries, and the increasing role of catalysis in environmental protection. The intellectual challenges for advancing the frontiers of catalytic science are outlined in Chapter 3. The human and institutional resources available in the US for carrying out research on catalysis are summarized in Chapter 4. The findings and recommendations of the panel for industry, academe, the national laboratories, and the federal government are presented in Chapter 5.

Not Available

1992-12-31T23:59:59.000Z

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

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

E-Print Network (OSTI)

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

Gulari, Erdogan

222

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

Science Conference Proceedings (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

223

Heterogeneous Catalyst for Improved Selectivity of Biomass ...  

Technology Marketing Summary. In today’s industrial processes, heterogeneous catalysts are widely used because of their stability and ease of ...

224

The effect of reservoir heterogeneity on gas production from hydrate accumulations in the permafrost  

SciTech Connect

The quantity of hydrocarbon gases trapped in natural hydrate accumulations is enormous, leading to significant interest in the evaluation of their potential as an energy source. Large volumes of gas can be readily produced at high rates for long times from methane hydrate accumulations in the permafrost by means of depressurization-induced dissociation combined with conventional technologies and horizontal or vertical well configurations. Initial studies on the possibility of natural gas production from permafrost hydrates assumed homogeneity in intrinsic reservoir properties and in the initial condition of the hydrate-bearing layers (either due to the coarseness of the model or due to simplifications in the definition of the system). These results showed great promise for gas recovery from Class 1, 2, and 3 systems in the permafrost. This work examines the consequences of inevitable heterogeneity in intrinsic properties, such as in the porosity of the hydrate-bearing formation, or heterogeneity in the initial state of hydrate saturation. Heterogeneous configurations are generated through multiple methods: (1) through defining heterogeneous layers via existing well-log data, (2) through randomized initialization of reservoir properties and initial conditions, and (3) through the use of geostatistical methods to create heterogeneous fields that extrapolate from the limited data available from cores and well-log data. These extrapolations use available information and established geophysical methods to capture a range of deposit properties and hydrate configurations. The results show that some forms of heterogeneity, such as horizontal stratification, can assist in production of hydrate-derived gas. However, more heterogeneous structures can lead to complex physical behavior within the deposit and near the wellbore that may obstruct the flow of fluids to the well, necessitating revised production strategies. The need for fine discretization is crucial in all cases to capture dynamic behavior during production.

Reagan, M. T.; Kowalsky, M B.; Moridis, G. J.; Silpngarmlert, S.

2010-05-01T23:59:59.000Z

225

Heterogeneities in the Glassy State  

E-Print Network (OSTI)

We study heterogeneities in a binary Lennard-Jones system below the glass transition using molecular dynamics simulations. We identify mobile and immobile particles and measure their distribution of vibrational amplitudes. For temperatures near the glass transition the distribution of vibrational amplitudes obeys scaling and compares reasonably well with a mean field theory for the amorphous solid state. To investigate correlations among the immobile and mobile particles we identify clusters and analyze their size and shape. For a fixed number of immobile particles we observe that the immobile particles cluster more strongly together as the temperature is increased which allows the particles to block each other more effectively, and to therefore stay immobile. For the mobile particles, on the other hand, the clustering is most pronounced at small temperatures, indicating that mobility at low temperatures can only be sustained in cooperative motion.

Katharina Vollmayr-Lee; Annette Zippelius

2005-07-05T23:59:59.000Z

226

HETEROGENEOUS REBURNING BY MIXED FUELS  

SciTech Connect

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.

Wei-Yin Chen; Benson B. Gathitu

2005-01-14T23:59:59.000Z

227

A Monte Carlo method of evaluating heterogeneous effects in plate-fueled reactors  

SciTech Connect

Few-group nuclear cross sections for small plate-fueled, light and heavy water test reactors are frequently generated with unit cell models that contain a homogeneous mixture of fuel, cladding, and water. The heterogeneous unit cells do not need to be represented explicitly for neutronics calculations when the plate and coolant channel thicknesses are small compared with the mean-free-path of neutrons. However, neutron and photon heating calculations were performed with heterogeneous fuel models to predict accurately the heat deposited in the fuel meat, cladding, and coolant. Heat deposited in the coolant channels and outside the fuel elements does not have a direct impact on the peak fuel meat temperature but must be included in the total coolant system heat balance. The results of a heterogeneous Monte Carlo calculation that estimates the heat loads in different fuel regions are presented and the fact that similar homogeneous fuel models can be used for many calculations. The calculations presented here were performed on models of the Advanced Neutron Source (ANS) and the Massachusetts Institute of Technology Reactor 2 (MITR-2). The ANS is a small, 362-MW (fission), plate-fueled, heavy water reactor designed to produce an intense steady-state source of neutrons.

Thayer, R.C.; Redmond, E.L. II; Ryskamp, J.M. (Idaho National Engineering Lab., Idaho Falls (United States))

1991-01-01T23:59:59.000Z

228

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

229

Hydrogen storage materials and method of making by dry homogenation  

DOE Green Energy (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

230

Heterogeneous CPU Services Using Differentiated Admission Control  

Science Conference Proceedings (OSTI)

We present an adaptive rate-controlled scheduler for heterogeneous applications running on general purpose computers. Our scheduler can effectively support diverse application requirements. It employs uniform rate-based sharing. Application heterogeneity ... Keywords: CPU scheduling, admission control, firewall protection, multimedia operating system, priority inversion, rate-based sharing

David K. Y. Yau; Bharat Bhargava

2002-07-01T23:59:59.000Z

231

Geometric Restraint Drives On- and Off-pathway Catalysis by the Escherichia coli Menaquinol:Fumarate Reductase  

SciTech Connect

Complex II superfamily members catalyze the kinetically difficult interconversion of succinate and fumarate. Due to the relative simplicity of complex II substrates and their similarity to other biologically abundant small molecules, substrate specificity presents a challenge in this system. In order to identify determinants for on-pathway catalysis, off-pathway catalysis, and enzyme inhibition, crystal structures of Escherichia coli menaquinol:fumarate reductase (QFR), a complex II superfamily member, were determined bound to the substrate, fumarate, and the inhibitors oxaloacetate, glutarate, and 3-nitropropionate. Optical difference spectroscopy and computational modeling support a model where QFR twists the dicarboxylate, activating it for catalysis. Orientation of the C2-C3 double bond of activated fumarate parallel to the C(4a)-N5 bond of FAD allows orbital overlap between the substrate and the cofactor, priming the substrate for nucleophilic attack. Off-pathway catalysis, such as the conversion of malate to oxaloacetate or the activation of the toxin 3-nitropropionate may occur when inhibitors bind with a similarly activated bond in the same position. Conversely, inhibitors that do not orient an activatable bond in this manner, such as glutarate and citrate, are excluded from catalysis and act as inhibitors of substrate binding. These results support a model where electronic interactions via geometric constraint and orbital steering underlie catalysis by QFR.

Tomasiak, Thomas M.; Archuleta, Tara L.; Andréll, Juni; Luna-Chávez, César; Davis, Tyler A.; Sarwar, Maruf; Ham, Amy J.; McDonald, W. Hayes; Yankovskaya, Victoria; Stern, Harry A.; Johnston, Jeffrey N.; Maklashina, Elena; Cecchini, Gary; Iverson, Tina M. (Rochester-Med); (VA); (Vanderbilt); (MRCLMB); (UCSF)

2012-01-05T23:59:59.000Z

232

Laboratory Simulation of Tidal Rectification over Seamounts: Homogeneous Model  

Science Conference Proceedings (OSTI)

The problem of the oscillatory motion of a homogeneous, rotating fluid in the vicinity of an isolated topographic feature is investigated in the laboratory and numerically. The laboratory experiments are conducted by fixing a cosine-squared body ...

Don L. Boyer; Gabriel Chabert d'Hieres; Henri Didelle; Jacques Verron; Rui-Rong Chen; Lijun Tao

1991-10-01T23:59:59.000Z

233

Homogenization of Radiosonde Temperature Time Series Using Innovation Statistics  

Science Conference Proceedings (OSTI)

Radiosonde temperature records contain valuable information for climate change research from the 1940s onward. Since they are affected by numerous artificial shifts, time series homogenization efforts are required. This paper introduces a new ...

Leopold Haimberger

2007-04-01T23:59:59.000Z

234

Homogenization Techniques for European Monthly Mean Surface Pressure Series  

Science Conference Proceedings (OSTI)

The quality of 51 series of surface pressure (extending back to between 1780 and 1871) over Europe is assessed using three different homogenization techniques. A new technique introduced here based on an iteration of multiple qualitative ...

V. C. Slonosky; P. D. Jones; T. D. Davies

1999-08-01T23:59:59.000Z

235

A compact setup to study homogeneous nucleation and condensation  

Science Conference Proceedings (OSTI)

An experiment is presented to study homogeneous nucleation and the subsequent droplet growth at high temperatures and high pressures in a compact setup that does not use moving parts. Nucleation and condensation are induced in an adiabatic

Mattias Karlsson; Ivo Alxneit; Frederik Rütten; Daniel Wuillemin; Hans Rudolf Tschudi

2007-01-01T23:59:59.000Z

236

Homogeneity of Gridded Precipitation Datasets for the Colorado River Basin  

Science Conference Proceedings (OSTI)

Inhomogeneity in gridded meteorological data may arise from the inclusion of inhomogeneous station data or from aspects of the gridding procedure itself. However, the homogeneity of gridded datasets is rarely questioned, even though an analysis ...

Galina Guentchev; Joseph J. Barsugli; Jon Eischeid

2010-12-01T23:59:59.000Z

237

Distribution of Radiation Density in a Homogeneous Cloudy Laye  

NLE Websites -- All DOE Office Websites (Extended Search)

of Radiation Density in a Homogeneous Cloudy Layer S. V. Dvoryashin, K. A. Shukorov, A. H. Shukurov, and G. S. Golitsyn A. M. Obukhov Institute of Atmospheric Physics Russian...

238

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

239

Cloud Droplet Growth by Condensation in Homogeneous Isotropic Turbulence  

Science Conference Proceedings (OSTI)

The growth of cloud droplets by diffusion of water vapor 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 ...

Alessandra S. Lanotte; Agnese Seminara; Federico Toschi

2009-06-01T23:59:59.000Z

240

Unsteady flows of in homogeneous in compressible fluids  

SciTech Connect

In this paper, we study the unsteady motion of in homogeneous in compressible viscous fluids. We present the results corresponding to Stokes second problem and for the flow between two parallel plates where one is oscillating.

Massoudi, Mehrdad; Vaidya, Ashwin

2011-01-01T23:59:59.000Z

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.


241

Conformational Diversity and Sub-states in Enzyme Catalysis | ornl.gov  

NLE Websites -- All DOE Office Websites (Extended Search)

Conformational Diversity and Sub-states in Enzyme Catalysis Conformational Diversity and Sub-states in Enzyme Catalysis November 01, 2013 Enzymes are great biocatalysts, and have attracted significant interest for industrial applications (including cellulosic ethanol) due to their remarkable catalytic efficiencies. The understanding of factors that enable enzymes to achieve the high catalytic efficiency will have large impact through design of new and powerful biocatalysts. Unfortunately, the understanding of these factors have largely remain a mystery so far. Using joint computational-experimental methodology we have developed a unique technique named quasi-anharmonic analysis (QAA) for identification of conformational diversity and conformational sub-states associated with enzyme function. As a result of this approach we have been able to develop

242

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

DOE Green Energy (OSTI)

The NACS has traditionally sought to encourage graduate student, and this year for the first time undergraduate studies, participation at the National Meetings and providing financial support is the most effective means to do so. Their attendance would contribute significantly to their scientific training and communication and presentation skills. They would be exposed to the leading researchers from the US and abroad; they would meet their peers from other universities; they would learn about cutting-edge results that could benefit their research projects; and they may become interested in becoming active participants in the catalysis community. These young investigators represent the next generation of scientists and engineers, and their proper training will lead to future scientific breakthroughs and technological innovations that benefit the US economy. Advances in catalysis can come in the form of more energy-efficient and environmentally-friendly chemical processes, improved fuel cell performance, efficient hydrogen production, and a cleaner environment.

Fabio H. Ribeiro

2011-06-05T23:59:59.000Z

243

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

SciTech Connect

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

Fabio H. Ribeiro

2011-06-05T23:59:59.000Z

244

Phase selectively soluble polymers for homogeneously supported catalysts  

E-Print Network (OSTI)

Soluble polymer supports that could be used in thermomorphic and latent biphasic systems have been prepared and analyzed for their potential application as supports for facilitated synthesis and catalysis. Phase selective solubilities were evaluated using polymers tagged with either visible dyes or fluorescent probes. Heptane/DMF, heptane/90% ethanol-water, heptane/ethyl acetate, heptane/ ethanol and heptane/tert-butanol solvent mixtures were all studied as examples of thermomorphic or latent biphasic systems. A range of polymers, including poly-(tert-butylstyrene) (PTBS), poly(alkylsiloxanes) (PAS), poly(dodecylvinylpyrrolidone) (PDVP), poly(didodecylvinylpyrrolidone (PDDVP), poly(isobutylene) (PIB), poly(octadecyl acrylate)s (PODA), and poly(octadecyl methacrylate)s (PODMA), were tested for hydrophobic phase selective solubility. The results of these studies were compared to prior work with polar and nonpolar poly(N-alkylacrylamide)s and polystyrene. Together with this prior work, these results have indicated that a wide range of polymers and solvent mixtures can be used for the recycling of soluble polymer-bound catalysts, reagents and sequestrants using either thermomorphic or latent biphasic separation strategies.Synthetic routes to terminally functionalized polyisobutylene oligomers, useful as supports in synthesis and catalysis, are also discussed and described. Such hydrocarbon polymers serve as highly soluble nonpolar analogs of well known poly(ethylene glycol) supports for synthesis and catalysis with the difference that the polymers are separated after a reaction by an extraction with alkane solvent. The synthesis of two polyisobutylene-supported phase transfer catalysts (PTC) are also described. These PTCs utilize the robust triazole functionality as a key synthetic step towards the preparation of the catalytic species. N alkylation of a PIB-supported triazole provides a direct route to the preparation of a PTC. Preparation of a tertiary phosphoninium salt containing a terminal alkyne allows simple attachment of the PTC to a PIB-supported azide via a triazole linker using Sharpless' Cu (I) [3 + 2] cycloaddition. These materials are active in catalyzing solid-liquid PTC and can be easily recycled by liquid-liquid extraction techniques.

Sung, Shayna D

2006-08-01T23:59:59.000Z

245

Genetic Programming for Evolving a Heterogenous Multi-agent System in a Dynamic Environment  

E-Print Network (OSTI)

The Robocup Rescue Simulation System (RCRSS) is dynamic system of of multi-agent interaction, simulating a large-scale urban disaster scenario. Teams of rescue agents are charged with the tasks of minimizing civilian casualties and infrastructure damage while competing against limitations on time, communication, and awareness. There have been numerous approaches to solving the problems of the RCRSS, but as of yet, no attempts to use Genetic Programming (GP) have been reported. GP is a popular form of automatic programming which utilizes the evolutionary mechanism of Genetic Algorithms (GA) to evolve a potentially complex program from simplistic primitives. This is the approach that will be used in this thesis to evolve the behaviours of a heterogenous set of cooperating agents for the RCRSS. Specifically, this thesis will study GP’s ability to evolve individual behaviours such as appropriate action selection, cooperation amongst homogenous and heterogenous teams of agents, and task assignment. 1 1

Andrew Runka; Dr. Vladimir Wojcik

2009-01-01T23:59:59.000Z

246

Stick-Slip Sliding of Water Drops on Chemically Heterogeneous Surfaces  

E-Print Network (OSTI)

We present a comprehensive study of water drops sliding down chemically heterogeneous surfaces formed by a periodic pattern of alternating hydrophobic and hydrophilic stripes. Drops are found to undergo a stick-slip motion whose average speed is an order of magnitude smaller than that measured on a homogeneous surface having the same static contact angle. This motion is the result of the periodic deformations of the drop interface when crossing the stripes. Numerical simulations confirm this view and are used to elucidate the principles underlying the experimental observations.

Silvia Varagnolo; Davide Ferraro; Paolo Fantinel; Matteo Pierno; Giampaolo Mistura; Giorgio Amati; Luca Biferale; Mauro Sbragaglia

2013-05-06T23:59:59.000Z

247

A Comparison of WD-EPMA Heterogeneity Testing ...  

Science Conference Proceedings (OSTI)

A Comparison of WD-EPMA Heterogeneity Testing Procedures. Summary: The heterogeneity of the four elements in a TiAl ...

2012-10-02T23:59:59.000Z

248

Reconciling Semantic Heterogeneity in Web Services Composition  

E-Print Network (OSTI)

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

Li, Xitong

249

Static LU Decomposition on Heterogeneous Platforms  

Science Conference Proceedings (OSTI)

In this paper, the authors deal with algorithmic issues on heterogeneous platforms. They concentrate on dense linear algebra kernels, such as matrix multiplication or LU decomposition. Block-cyclic distribution techniques used in ScaLAPACK are no longer ...

Olivier Beaumont; Arnaud Legrand; Fabrice Rastello; Yves Robert

2001-08-01T23:59:59.000Z

250

A Computationally Based Approach to Homogenizing Advanced Alloys  

SciTech Connect

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

Jablonski, P D; Cowen, C J

2011-02-27T23:59:59.000Z

251

Global well-posedness for the homogeneous Landau equation  

E-Print Network (OSTI)

Global well-posedness and exponential decay to equilibrium are proved for the homogeneous Landau equation from kinetic theory. The initial distribution is only assumed to be bounded and decaying sufficiently fast at infinity. In particular, discontinuous initial configurations that might be far from equilibrium are covered. Despite the lack of a comparison principle for the equation, the proof of existence relies on barrier arguments and parabolic regularity theory. Uniqueness and decay to equilibrium are then obtained through weighted integral inequalities. Although the focus is on the spatially homogeneous case with Coulomb potential, the methods introduced here may be applied elsewhere in nonlinear kinetic theory.

Maria Gualdani; Nestor Guillen

2013-05-10T23:59:59.000Z

252

--No Title--  

NLE Websites -- All DOE Office Websites (Extended Search)

CATALYSIS Home About CATALYSIS Staff Alphabetical Area of Research Research Automotive Emissions Characterization ComputationTheory Enzymatic Heterogeneous Surface Science...

253

"Conservation Laws in Elasticity II. Linear Homogeneous Isotropic Elastostatics"  

E-Print Network (OSTI)

Errata "Conservation Laws in Elasticity II. Linear Homogeneous Isotropic Elastostatics" Archive tensor. They differ by a trivial conservation law z~a- S=/~(Vu r- (V'u) I), where "trivial" means conservation laws introduced on page 139, 4 = EHmBlm') (**) How does this affect the results in the paper

Olver, Peter

254

Conservation Laws in Elasticity II. Linear Homogeneous Isotropic Elastostatics  

E-Print Network (OSTI)

Conservation Laws in Elasticity II. Linear Homogeneous Isotropic Elastostatics PETER J. OLVER conservation laws. The importance of this quantity was demonstrated in its rediscovery and use by RICE [19 symmetries and conservation laws had been available since 1918, [14]. Be that as it may, the elementary

Olver, Peter

255

Homogeneous catalytic hydrogenations of complex carbonaceous substrates. [16 references  

SciTech Connect

Results of homogeneous catalytic hydrogenation of complex unsaturated substrates including coal and coal-derived materials are reported, with organic soluble molecular complexes as catalysts. Among the substrates used were Hvab coal, solvent-refined coal, and COED pyrolysate. The hydrogenations were carried out in an autoclave. The results are summarized in tables.

Cox, J L; Wilcox, W A; Roberts, G L

1976-11-05T23:59:59.000Z

256

On the Development and Use of Homogenized Climate Datasets  

Science Conference Proceedings (OSTI)

At the National Climatic Data Center, two basic approaches to making homogeneity adjustments to climate data have been developed. The first is based on the use of metadata (station history files) and is used in the adjustments made to the U.S. ...

David R. Easterling; Thomas C. Peterson; Thomas R. Karl

1996-06-01T23:59:59.000Z

257

Catalysis and activation of magic states in fault-tolerant architectures  

Science Conference Proceedings (OSTI)

In many architectures for fault-tolerant quantum computing universality is achieved by a combination of Clifford group unitary operators and preparation of suitable nonstabilizer states, the so-called magic states. Universality is possible even for some fairly noisy nonstabilizer states, as distillation can convert many noisy copies into fewer purer magic states. Here we propose protocols that exploit multiple species of magic states in surprising ways. These protocols provide examples of previously unobserved phenomena that are analogous to catalysis and activation well known in entanglement theory.

Campbell, Earl T. [Department of Physics and Astronomy, University College London, Gower Street, London WC1E 6BT (United Kingdom) and Institute of Physics and Astronomy, University of Potsdam, D-14476 Potsdam (Germany)

2011-03-15T23:59:59.000Z

258

Quasi-heterogeneous efficient 3-D discrete ordinates CANDU calculations using Attila  

SciTech Connect

In this paper, 3-D quasi-heterogeneous large scale parallel Attila calculations of a generic CANDU test problem consisting of 42 complete fuel channels and a perpendicular to fuel reactivity device are presented. The solution method is that of discrete ordinates SN and the computational model is quasi-heterogeneous, i.e. fuel bundle is partially homogenized into five homogeneous rings consistently with the DRAGON code model used by the industry for the incremental cross-section generation. In calculations, the HELIOS-generated 45 macroscopic cross-sections library was used. This approach to CANDU calculations has the following advantages: 1) it allows detailed bundle (and eventually channel) power calculations for each fuel ring in a bundle, 2) it allows the exact reactivity device representation for its precise reactivity worth calculation, and 3) it eliminates the need for incremental cross-sections. Our results are compared to the reference Monte Carlo MCNP solution. In addition, the Attila SN method performance in CANDU calculations characterized by significant up scattering is discussed. (authors)

Preeti, T. [Univ. of Ontario, Inst. of Technology, 2000 Simcoe Street North, Oshawa, ON L1H 7K4 (Canada); Rulko, R. [Canadian Nuclear Safety Commission, 280 Slater Street, Ottawa, ON K1P 5S9 (Canada)

2012-07-01T23:59:59.000Z

259

Pure-state transformations and catalysis under operations that completely preserve positivity of partial transpose  

E-Print Network (OSTI)

Motivated by the desire to better understand the class of quantum operations on bipartite systems that preserve positivity of partial transpose (PPT operations) and its relation to the class LOCC (local operations and classical communication), we present some results on deterministic bipartite pure state transformations by PPT operations. Restricting our attention to the case where we start with a rank K maximally entangled state, we give a necessary condition for transforming it into a given pure state, which we show is also sufficient when K is two and the final state has Schmidt rank three. We show that it is sufficient for all K and all final states provided a conjecture about a certain family of semidefinite programs is true. We also demonstrate that the phenomenon of catalysis can occur under PPT operations and that, unlike LOCC catalysis, a maximally entangled state can be a catalyst. Finally, we give a necessary and sufficient condition for the possibility of transforming a rank K maximally entangled state to an arbitrary pure state by PPT operations assisted by some maximally entangled catalyst.

William Matthews; Andreas Winter

2008-01-28T23:59:59.000Z

260

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

DOE Green Energy (OSTI)

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

Whitelaw, J.H.

1997-06-30T23:59:59.000Z

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

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

262

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

263

Homogeneous decoherence functionals in standard and history quantum mechanics  

E-Print Network (OSTI)

General history quantum theories are quantum theories without a globally defined notion of time. Decoherence functionals represent the states in the history approach and are defined as certain bivariate complex-valued functionals on the space of all histories. However, in practical situations -- for instance in the history formulation of standard quantum mechanics -- there often is a global time direction and the homogeneous decoherence functionals are specified by their values on the subspace of homogeneous histories. In this work we study the analytic properties of (i) the standard decoherence functional in the history version of standard quantum mechanics and (ii) homogeneous decoherence functionals in general history theories. We restrict ourselves to the situation where the space of histories is given by the lattice of projections on some Hilbert space H. Among other things we prove the non-existence of a finitely valued extension for the standard decoherence functional to the space of all histories, derive a representation for the standard decoherence functional as an unbounded quadratic form with a natural representation on a Hilbert space and prove the existence of an Isham-Linden-Schreckenberg (ILS) type representation for the standard decoherence functional.

Oliver Rudolph; J. D. M. Wright

1998-07-23T23:59:59.000Z

264

Error resilient video streaming for heterogeneous networks  

Science Conference Proceedings (OSTI)

We consider the problem of video streaming for a critical private web cast, for a medium sized audience with heterogeneous nodes having different bandwidths and reliabilities. The nodes can distribute video in a peer-to-peer manner by forming a multicast ... Keywords: error resilience, multiple description coding (MDC), path diversity, video streaming

Divyashikha Sethia; Huzur Saran

2006-12-01T23:59:59.000Z

265

Architecture for mobile Heterogeneous Multi Domain networks  

Science Conference Proceedings (OSTI)

Multi domain networks can be used in several scenarios including military, enterprize networks, emergency networks and many other cases. In such networks, each domain might be under its own administration. Therefore, the cooperation among domains is ... Keywords: Network architecture, heterogeneous networks, mobility, policy based networking

Arjan Durresi; Ping Zhang; Mimoza Durresi; Leonard Barolli

2010-01-01T23:59:59.000Z

266

Multiscale not multicore: efficient heterogeneous cloud computing  

Science Conference Proceedings (OSTI)

In this paper, we present a vision of the future of heterogeneous cloud computing. Ours is a cleanslate approach, sweeping away decades of accreted system software. We believe the advent of the latest technology discontinuity---the move to the virtual ...

Anil Madhavapeddy; Richard Mortier; Jon Crowcroft; Steven Hand

2010-04-01T23:59:59.000Z

267

A Metering Infrastructure for Heterogenous Mobile Networks  

E-Print Network (OSTI)

A Metering Infrastructure for Heterogenous Mobile Networks Andreas Monger, Marc Fouquet, Christian decision engines is costly in terms of bandwidth. With our flexible Generic Metering Infrastructure (GMI-assisted handovers. We present the Generic Metering Infrastructure (GMI) that #12;is able to provide decision making

Carle, Georg

268

Freezing Rate Due to Heterogeneous Nucleation  

Science Conference Proceedings (OSTI)

The heterogeneous nucleation of ice from supercooled water is influenced by the nature of the foreign nuclei that serve as the sites for ice embryo formation, and by the stochastic nature of the process of embryo growth to critical size. The ...

Gabor Vali

1994-07-01T23:59:59.000Z

269

Real time video streaming over heterogeneous networks  

Science Conference Proceedings (OSTI)

Technological advances allow handheld devices to be equipped with faster processors and wireless interfaces, making the performance comparable to laptop Computers. In this paper, we describe real-time video streaming over heterogeneous networks namely ... Keywords: GPRS-EDGE, IEEE802.11, IETF, MPEG-4, PSS, RTCP, RTP, RTSP, bluetooth, performance, piconet, quality of service, video streaming, wireless LANs

Mohammed A. Qadeer; Rehan Ahmad; Mohd Siddique Khan; Tauseef Ahmad

2009-02-01T23:59:59.000Z

270

Combining heterogeneous temporal information: A case study  

Science Conference Proceedings (OSTI)

In this paper we present a specialized system for temporal reasoning representing possibly uncertain qualitative and quantitative constraints relative to temporal intervals in a homogeneous framework. The underlying logic is that of Allen, which we have ... Keywords: Constraints, Task Scheduling, Temporal Reasoning

Silvana Badaloni

1999-04-01T23:59:59.000Z

271

Catalysis Letters 59 (1999) 9394 93 Stepwise methane steam reforming: a route to CO-free hydrogen  

E-Print Network (OSTI)

Catalysis Letters 59 (1999) 93­94 93 Stepwise methane steam reforming: a route to CO-free hydrogen-free hydrogen. Keywords: methane decomposition, Ni/zirconia, steam gasification In order to utilize hydrogen of impurities, particularly carbon monoxide. Steam reforming, partial oxidation and au- tothermal reforming [1

Goodman, Wayne

272

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

273

Characterization of oil and gas reservoir heterogeneity  

SciTech Connect

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

274

Acid Catalysis in Basic Solution: A Supramolecular Host PromotesOrthoformate Hydrolysis  

DOE Green Energy (OSTI)

Though many enzymes can promote chemical reactions by tuning substrate properties purely through the electrostatic environment of a docking cavity, this strategy has proven challenging to mimic in synthetic host-guest systems. Here we report a highly-charged, water soluble, metal-ligand assembly with a hydrophobic interior cavity that thermodynamically stabilizes protonated substrates and consequently catalyzes the normally acidic hydrolysis of orthoformates in basic solution, with rate accelerations of up to 890-fold. The catalysis reaction obeys Michaelis-Menten kinetics, exhibits competitive inhibition, and the substrate scope displays size selectivity consistent with the constrained binding environment of the molecular host. Synthetic chemists have long endeavored to design host molecules capable of selectively binding slow-reacting substrates and catalyzing their chemical reactions. While synthetic catalysts are often site-specific and require certain properties of the substrate to insure catalysis, enzymes are often able to modify basic properties of the bound substrate such as pK{sub a} in order to enhance reactivity. Two common motifs used by nature to activate otherwise unreactive compounds are the precise arrangement of hydrogen-bonding networks and electrostatic interactions between the substrate and adjacent residues of the protein. Precise arrangement of hydrogen bonding networks near the active sites of proteins can lead to well-tuned pK{sub a}-matching, and can result in pK{sub a} shifts of up to eight units, as shown in bacteriorhodopsin. Similarly, purely electrostatic interactions can greatly favor charged states and have been responsible for pK{sub a} shifts of up to five units for acetoacetate decarboxylase. Attempts have been made to isolate the contributions of electrostatic versus covalent interactions to such pK{sub a} shifts; however this remains a difficult challenge experimentally. This challenge emphasizes the importance of synthesizing host molecules that, like enzyme cavities, can enhance binding of small molecular guests and, in a few cases, catalyze chemical reactions. Supramolecular assemblies with available functional groups have been used to generate solution-state pK{sub a} shifts of up to two pK{sub a} units and to catalyze chemical reactions. Synthetic hosts often rely on hydrogen-bonding or ion-dipole interactions for guest inclusion, and numerous studies have investigated the effects of charge on guest binding affinities in supramolecular host-guest systems. We report here a synthetic supramolecular host assembly that relies exclusively on electrostatic and hydrophobic interactions for thermodynamic stabilization of protonated substrates. As nature has exploited pK{sub a} shifts to activate otherwise unreactive substrates toward catalysis, this stabilization is exploited to promote acid-catalyzed hydrolyses in strongly basic solution.

Pluth, Michael D.; Bergman, Robert G.; Raymond, Kenneth N.

2007-12-12T23:59:59.000Z

275

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

DOE Green Energy (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

276

Argonne CNM Highlight: Gold nanoparticles create visible-light catalysis in  

NLE Websites -- All DOE Office Websites (Extended Search)

Silver chloride-gold nanoparticles Gold-coated silver chloride (AgCl) nanowires at the microscopic level. In the News United Press International | PhysOrg.com | R&D Magazine| Nanotechnology Now | Photonics.com Gold nanoparticles create visible-light catalysis in nanowires A two-step approach has been developed within the Nanophotonics Group to synthesize AgCl nanowires decorated with gold nanoparticles by using silver nanowires as chemical templates. In the first step, the silver nanowires are chemically oxidized and converted to AgCl nanowires. In the second step, ions generated in the first step reduce gold precursors (e.g., NaAuCl4) to deposit gold nanoparticles on the AgCl nanowire surfaces, resulting in the formation of AgCl:gold composite nanowires. Because of the

277

Enantioselective Catalysis of the Aza-Cope Rearrangement by a Chiral Supramolecular Assembly  

SciTech Connect

The chiral supramolecular catalyst Ga{sub 4}L{sub 6} [L = 1,5-bis(2,3-dihydroxybenzoylamino)naphthalene] is a molecular tetrahedron that catalyzes the 3-aza-Cope rearrangement of allyl enammonium cations. This catalysis is accomplished by preorganizing the substrate in a reactive conformation within the host. This work demonstrates that through the use of enantiopure assembly, its chiral cavity is capable of catalyzing the 3-aza-Cope rearrangement enantioselectively, with yields of 21-74% and enantiomeric excesses from 6 to 64% at 50 C. At lower temperatures, the enantioselectivity improved, reaching 78% ee at 5 C. This is the highest enantioselectivity to date induced by the chiral cavity of a supramolecular assembly.

Brown, Casey J.; Bergman, Robert G.; Raymond, Kenneth N.

2009-07-29T23:59:59.000Z

278

Superacid catalysis of light hydrocarbon conversion. Sixth quarterly report, January 1, 1995--March 31, 1995  

DOE Green Energy (OSTI)

Iron- and Manganese-promoted sulfated zirconia is a catalyst for the conversion of propane, but the rate of conversion of propane is much less than the rate of conversion of butane. Whereas this catalyst appears to be a good candidate for practical, industrial conversion of butane, it appears to lack sufficient activity for practical conversion of propane. Perhaps more active catalysts will be useful for propane conversion. The propane conversion data reported here provide excellent insights into the chemistry of the catalytic conversions; they are consistent with the inference that the catalyst is a superacid and that the chemistry is analogous to. that determined in superacid solutions by G.A. Olah, who was awarded the most recent Nobel Prize in chemistry for his work. The catalyst was tested for conversion of propane at 1 bar, 200--300{degrees}C and propane partial pressures in the range of 0.01--0.05 bar. At 250{degrees}C, catalysis was demonstrated, as the number of propane molecules converted was at least 1 per sulfate group after 16 days of operation in a continues flow reactor. Propane was converted in high yield to butanes, but the conversions were low, for example being only a fraction of a percent at a space velocity of 9.1 {times} 10{sup {minus}7} mol(g of catalysis {center_dot} s) and 250{degrees}C. Coke formation was rapid. The observation of butanes, pentanes, and methane as products is consistent with Olah superacid chemistry, whereby propane is first protonated by a very strong acid to form a carbonium ion. The carbonium ion then decomposes into methane and an ethyl cation which undergoes oligocondensation reactions with propane to form higher molecular weight alkanes. The results are consistent with the identification of iron- and manganese-promoted sulfated zirconia as a superacid.

Gates, B.C. [California Univ., Davis, CA (United States). Dept. of Chemical Engineering and Materials Science

1995-08-01T23:59:59.000Z

279

Homogeneously catalyzed synthesis gas transformations to oxygenate fuels  

DOE Green Energy (OSTI)

At Brookhaven National Laboratory (BNL), the ongoing oxygenates synthesis program is addressing the catalytic synthesis gas conversion to liquid fuels and fuel additives. The major thrust of this effort is to enhance carbon conversion, reaction rates, product selectivity and overall process efficiency. To this effect, a series of liquid phase homogeneous catalysts have been developed and successfully utilized in the synthesis of methanol and other oxygenates. This paper identifies advantages and uncertainties associated with these newly developed catalysts. The effect of system parameters on the overall process scheme is discussed.

Mahajan, D.; Mattas, L.; Sanchez, J.

1992-01-01T23:59:59.000Z

280

Homogeneously catalyzed synthesis gas transformations to oxygenate fuels  

DOE Green Energy (OSTI)

At Brookhaven National Laboratory (BNL), the ongoing oxygenates synthesis program is addressing the catalytic synthesis gas conversion to liquid fuels and fuel additives. The major thrust of this effort is to enhance carbon conversion, reaction rates, product selectivity and overall process efficiency. To this effect, a series of liquid phase homogeneous catalysts have been developed and successfully utilized in the synthesis of methanol and other oxygenates. This paper identifies advantages and uncertainties associated with these newly developed catalysts. The effect of system parameters on the overall process scheme is discussed.

Mahajan, D.; Mattas, L.; Sanchez, J.

1992-04-01T23:59:59.000Z

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281

Homogeneous bubble nucleation predicted by a molecular interaction model  

SciTech Connect

The homogenous bubble nucleation of various hydrocarbons was estimated by the modified classical nucleation theory. In this modification, the kinetic formalism of the classical theory is retained while the surface energy needed for the bubble formation is calculated form the interaction energy between molecules. With a nucleation rate value of J{sub n{sub c}} = 10{sup 22} nuclei/cm{sup 3}s, this modified model gives a very good prediction of the superheat limits of liquids. In another test of the model the complete evaporation time of a butane droplet at its superheat limit is compared with experiments and found to be in good agreement.

Hoyoung Kwak; Sangbum Lee (Chung-Ang Univ., Seoul (Korea))

1991-08-01T23:59:59.000Z

282

On the ordering of energy levels in homogeneous magnetic fields  

E-Print Network (OSTI)

We study the energy levels of a single particle in a homogeneous magnetic field and in an axially symmetric external potential. For potentials that are superharmonic off the central axis, we find a general ``pseudoconcave'' ordering of the ground state energies of the Hamiltonian restricted to the sectors with fixed angular momentum. The physical applications include atoms and ions in strong magnetic fields. There the energies are monotone increasing and concave in angular momentum. In the case of a periodic chain of atoms the pseudoconcavity extends to the entire lowest band of Bloch functions.

Bernhard Baumgartner; Robert Seiringer

2000-11-17T23:59:59.000Z

283

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

284

Preliminary development of thermal nuclear cell homogenization code  

SciTech Connect

Nuclear fuel cell homogenization for thermal reactors usually include three main parts, i.e., fast energy resonance part which usually adopt narrow resonance approximation to treat the resonance, low (intermediate) energy region in which the resonance can not be treated accurately using NR approximation and therefore we should use intermediate resonance treatment, and thermal energy region (very low) in which the effect of thermal must be treated properly. In n this study the application of the intermediate resonance approximation treatment for low energy nuclear resonance is discussed. The method is iterative based. As a sample the method is applied in U-235 low lying resonance and the result is presented and discussed.

Su'ud, Z.; Shafii, M. A.; Yudha, S. P.; Waris, A.; Rijal, K. [Nuclear Research group, Faculty of Mathematics and Natural Sciences, Bandung Institute of Technology, Jl. Ganesha 10, Bandung40132 (Indonesia)

2012-06-06T23:59:59.000Z

285

Reliability-aware scheduling strategy for heterogeneous distributed computing systems  

Science Conference Proceedings (OSTI)

Heterogeneous computing systems are promising computing platforms, since single parallel architecture based systems may not be sufficient to exploit the available parallelism with the running applications. In some cases, heterogeneous distributed computing ... Keywords: Duplication, Heterogeneous distributed systems, Precedence constrained tasks, Reliability, Scheduling algorithm

Xiaoyong Tang; Kenli Li; Renfa Li; Bharadwaj Veeravalli

2010-09-01T23:59:59.000Z

286

List scheduling with duplication for heterogeneous computing systems  

Science Conference Proceedings (OSTI)

Effective task scheduling is essential for obtaining high performance in heterogeneous computing systems (HCS). However, finding an effective task schedule in HCS, requires the consideration of the heterogeneity of computation and communication. To solve ... Keywords: DAG, Duplication, Heterogeneous computing systems, List scheduling

Xiaoyong Tang; Kenli Li; Guiping Liao; Renfa Li

2010-04-01T23:59:59.000Z

287

Experimental Analysis of Heterogeneous Wireless Networks  

E-Print Network (OSTI)

Packet loss and delay in Internet degrade the quality of requested services like VoIP (Voice over IP) or Video Streaming. In novel network scenarios where wired and wireless connections are melted together, a real measure of these parameters is fundamental in a planning process of new services over novel network infrastructures. Nowadays networks are heterogeneous in terms of access network technologies (wired LAN Ethernet 10/100/1000, Wireless LAN - 802.11a, 802.11b, 802.11g -, GPRS, UMTS, GSM, Bluetooth, ...), end-users' devices (workstation, PC desktop, Laptop/Notebook, PDA, Advanced Mobile Phone, ...) and finally operating systems (Unix, Linux, Win 98/NT/2000/XP, Win CE, Linux Familiar, OS Embedded, ...). In this work we provide a heterogeneous network performance characterization with respect to delay and throughput in UDP and TCP environments. In order to determine our results we use an innovative traffic generator named D-ITG (Distributed Internet Traffic Generator). Results presented in this paper can be used as performance references for development of wireless communication applications over multiservice and heterogeneous networks.

Giulio Iannello; Antonio Pescape; Giorgio Ventre; Luca Vollero

2004-01-01T23:59:59.000Z

288

Method of Producing Ultra-heavy Homogeneous Aerosol of Sub-micron...  

NLE Websites -- All DOE Office Websites (Extended Search)

Method of Producing Ultra-heavy Homogeneous Aerosol of Sub-micron Particles Ernest J. Valeo and Nathaniel J. Fisch This invention forms a heavy homogeneous aerosol by agitating...

289

An Investigation of Linked Physical And Biogeochemical Processes In Heterogeneous Soils In The Vadose Zone  

E-Print Network (OSTI)

Chemical dynamics in the vadose zone are poorly understood due to the transient nature of chemical and hydrologic conditions, but are nonetheless critical to understanding contaminant fate and transport. This work explored the effects of soil structure (i.e. layers, lenses) on linked geochemical, hydrological, and microbiological processes under changing hydrologic conditions (e.g. rainfall, introduction of groundwater, and fluctuating water table heights). A homogenized medium-grained sand, homogenized organic-rich loam and a sand-over-loam layered column were constructed for the first series of experiments. The second series of experiments employed two soil columns with lenses that were packed identically with sterilized and untreated sediments. Each consisted of two lenses of organic-rich loam in a medium-grained sand matrix. Lenses were located at different vertical depths and were horizontally offset. In-situ collocated probes collected soil hydrologic and chemical data. In the layered column, enhanced biogeochemical cycling was observed over the texturally homogeneous soil columns. Enumerations of Fe(III) and SO42- reducing microorganisms also show 1-2 orders of magnitude greater community numbers in the layered column. The greatest concentrations of aqueous FeS clusters (FeSaq) were observed in close proximity to the soil interface. To our knowledge, this was the first documentation of FeSaq in partially saturated sediments. Mineral and soil aggregate composite layers were also most abundant near the soil layer interface; the presence of which, likely contributed to an order of magnitude decrease of hydraulic conductivity. In the live lens column, Fe-oxide bands formed at the fringes of the lenses that retarded water flow rates by an order of magnitude compared to the sterilized column. Microbial activity also produced insoluble gases and that led to the creation of a separate gas phase that reduced hydraulic conductivity. This limited the interaction between groundwater with soil-pore waters that led to the formation of geochemically distinct water masses in relatively close proximity to one another. No such changes were observed in the sterilized column. When compared to homogenous columns, the presence of soil heterogeneities altered biogeochemical and hydrologic processes considerably which highlights the need to consider soil heterogeneity in contaminant fate and transport models. These findings suggest that quantifying coupled hydrologic-biogeochemical processes occurring at small scale soil interfaces is critical to accurately describing and predicting chemical changes at the larger system scale.

Hansen, David Joseph

2011-08-01T23:59:59.000Z

290

Critical Casimir forces between homogeneous and chemically striped surfaces  

E-Print Network (OSTI)

Recent experiments have measured the critical Casimir force acting on a colloid immersed in a binary liquid mixture near its continuous demixing phase transition and exposed to a chemically structured substrate. Motivated by these experiments, we study the critical behavior of a system, which belongs to the Ising universality class, for the film geometry with one planar wall chemically striped, such that there is a laterally alternating adsorption preference for the two species of the binary liquid mixture, which is implemented by surface fields. For the opposite wall we employ alternatively a homogeneous adsorption preference or homogeneous Dirichlet boundary conditions, which within a lattice model are realized by open boundary conditions. By means of mean-field theory, Monte Carlo simulations, and finite-size scaling analysis we determine the critical Casimir force acting on the two parallel walls and its corresponding universal scaling function. We show that in the limit of stripe widths small compared with the film thickness, on the striped surface the system effectively realizes Dirichlet boundary conditions, which generically do not hold for actual fluids. Moreover, the critical Casimir force is found to be attractive or repulsive, depending on the width of the stripes of the chemically patterned surface and on the boundary condition applied to the opposing surface.

Francesco Parisen Toldin; Matthias Tröndle; S. Dietrich

2013-03-25T23:59:59.000Z

291

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

292

Effects of Spatial and Temporal Heterogeneity of Channel Bandwidth on Performance of Individual Messages in Heterogeneous Communication Networks  

Science Conference Proceedings (OSTI)

Channel bandwidth available for a message on a communication network varies with time and link. This variation (heterogeneity) can have a significant effect on performance of an individual message and also that of the network as a whole. Therefore, it ... Keywords: Channel bandwidth, End-to-end delay, Multipath data transfer, Path selection, Spatial heterogeneity, Temporal heterogeneity, Throughput

Soo-Young Lee; Jun Huang

2004-08-01T23:59:59.000Z

293

Posters Triggering of Boundary Layer Cumulus Clouds Over a Heterogeneous Surface  

NLE Websites -- All DOE Office Websites (Extended Search)

5 5 Posters Triggering of Boundary Layer Cumulus Clouds Over a Heterogeneous Surface K. Schrieber, R. Stull, and Q. Zhang Boundary Layer Research Team Department of Atmospheric and Oceanic Science University of Wisconsin Madison, Wisconsin Complex multimodal joint frequency distributions of LCL height versus θ v in surface-layer air over a large heteroge- neous surface area are modeled as the superposition of simpler mono-modal distributions. These simpler distri- butions, which apply to quasi-homogeneous subdomains, are approximated with bivariate distribution models. The shape of each of these modeled distributions depends on variations of the Bowen ratio and heat input forcings. These forcings are a function of the landscape, insolation, surface albedo, cloud-shading, soil moisture, and other

294

Carbon Tetrachloride and Chloroform Attenuation Parameter Studies: Heterogeneous Hydrolytic Reactions -- Status Report  

Science Conference Proceedings (OSTI)

This report documents a project initiated in FY 2006 to help address uncertainties related to the rates of hydrolysis in groundwater for carbon tetrachloride (CT) and chloroform (CF). The study sought also to explore the possible effects of contact with minerals and sediment (i.e., heterogeneous hydrolysis) on these rates. It was funded by the U.S. Department of Energy (DOE) through the Office of Environmental Management Columbia River Protection Supplemental Technologies (CRPST) project and complements work initiated by the Hanford Groundwater Project in FY 2006 that focused primarily on CT in homogenous solution. Work was performed by staff at the Pacific Northwest National Laboratory (PNNL) and the State University of New York at Cortland (SUNY-Cortland).

Amonette, James E.; Qafoku, Odeta; Wietsma, Thomas W.; Jeffers, Peter M.; Russell, Colleen K.; Truex, Michael J.

2009-09-18T23:59:59.000Z

295

Geometry and heterogeneous effects on the neutronic performance of a Yin Yang mirror-reactor blanket  

SciTech Connect

From 5th symposium on engineering problems of fusion research; Princeton, New Jersey, USA (6 Nov 1973). Two-dimensional models and Monte Carlo neutron transport techniques were used to calculate the tritium breeding and energy generation in a mirror-reactor blanket. Results indicate that blanket performance should be quite insensitive to variations in overall geometry as long as there are no large neutron-leakage paths. Injection and leakage penetration can be accommodated as long as the first-wall peneiration area subtends less than 25% of the first wall's spherical area. Heterogeneous and streaming effects in a tubular blanket can be important, but are negligible for closely packed arrays of tubes. The one-dimensional homogeneous spherical-shell model appears to be a useful tool for predicting performance of a tubular blanket conforming to the YinYang mirror geometry. (auth)

Lee, J.D.

1973-10-17T23:59:59.000Z

296

Parametric Gasification of Oak and Pine Feedstocks Using the TCPDU and Slipstream Water-Gas Shift Catalysis  

NLE Websites -- All DOE Office Websites (Extended Search)

Parametric Gasification of Oak Parametric Gasification of Oak and Pine Feedstocks Using the TCPDU and Slipstream Water-Gas Shift Catalysis Jason Hrdlicka, Calvin Feik, Danny Carpenter, and Marc Pomeroy Technical Report NREL/TP-510-44557 December 2008 Parametric Gasification of Oak and Pine Feedstocks Using the TCPDU and Slipstream Water-Gas Shift Catalysis Jason Hrdlicka, Calvin Feik, Danny Carpenter, and Marc Pomeroy Prepared under Task No. H2713B13 Technical Report NREL/TP-510-44557 December 2008 National Renewable Energy Laboratory 1617 Cole Boulevard, Golden, Colorado 80401-3393 303-275-3000 * www.nrel.gov NREL is a national laboratory of the U.S. Department of Energy Office of Energy Efficiency and Renewable Energy Operated by the Alliance for Sustainable Energy, LLC

297

Combined homo- and heterogeneous model for mercury speciation in pulverized fuel combustion flue gases  

SciTech Connect

A new model is developed to predict Hg{sup 0}, Hg{sup +}, Hg{sup 2+}, and Hg{sub p} in the post-combustion zone upstream of a particulate control device (PCD) in pulverized coal-fired power plants. The model incorporates reactions of mercury with chlorinating agents (HCl) and other gaseous species and simultaneous adsorption of oxidized mercury (HgCl{sub 2}) on fly ash particles in the cooling of flue gases. The homogeneous kinetic model from the literature has been revised to understand the effect of the NO + OH + M {longleftrightarrow} HONO + M reaction on mercury oxidation. Because it is a pressure-dependent reaction, the choice of proper reaction rates was very critical. It was found that mercury oxidation reduces from 100 to 0% while going from high- to low-pressure limit rates with 100 ppmv NO. The heterogeneous model describes selective in-duct Langmuir-Hinshelwood adsorption of mercury chloride on ash particles. The heterogeneous model has been built using Fortran and linked to Chemkin 4.0. The final predictions of elemental, oxidized, and particulate mercury were compared to mercury speciation from power plant data. Information collection request (ICR) data were used for this comparison. The model results follow very similar trends compared to those of the plant data; however, quantitative deviation was considerable. These deviations are due to the errors in the measurement of mercury upstream of PCD, lack of adsorption kinetic data, accurate homogeneous reaction mechanisms, and certain modeling assumptions. The model definitely follows a new approach for the prediction of mercury speciation, and further refinement will improve the model significantly. 43 refs., 1 figs., 6 tabs.

Shishir P. Sable; Wiebren de Jong; Hartmut Spliethoff [Delft University Technology, Delft (Netherlands). Section Energy Technology, Department of Process and Energy

2008-01-15T23:59:59.000Z

298

The Universe Adventure - The Homogenous and Isotropic Universe  

NLE Websites -- All DOE Office Websites (Extended Search)

Our View of the Universe Our View of the Universe All observations that have been made using the most powerful telescopes show that the universe looks the same in all directions. The average density of galaxies is the same throughout the universe and does not change with distance or direction. This is called the Cosmological Principle. Distribution of Galaxies On average and at large scales, the distribution of galaxies is the same throughout the universe. Since the expansion of space occurs evenly at every point in the universe, galaxies are separating from each other at about the same pace, giving the universe a nearly uniform density and structure. As a result, the universe appears smooth at large distance scales. In scientific terms, it is said to be homogeneous and isotropic.

299

Decline curve derivative analysis for homogeneous and composite reservoirs  

DOE Green Energy (OSTI)

In this study, the rate decline and rate decline derivatives of a constant pressure well are presented for infinite, constant pressure outer boundary, and closed outer boundary homogeneous reservoirs. A rate derivative type curve is provided for these cases as well. The effects of the dimensionless reservoir exterior radius are discussed. Rate decline and rate decline derivatives of a constant pressure well in an infinite composite reservoir are also presented. For composite reservoirs, the effects of mobility ratios and discontinuity distance on both rate decline and rate decline derivatives are presented. Type curves for dimensionless wellbore flow rate derivatives for infinite composite reservoirs are provided. A new correlating group for the derivative type curve is provided, and is different than the correlating group for the rate type curve presented in the past. Finally, an analysis method that comprises type curve and derivative type curve matching to determine the dimensionless variables is proposed and demonstrated with a simulated example.

Demski, J.A.

1987-06-01T23:59:59.000Z

300

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.

Giacomin, Giambattista

2007-01-01T23:59:59.000Z

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
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301

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

302

The manufacture and performance of homogeneous microstructure SBR MOX fuel  

Science Conference Proceedings (OSTI)

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

Barker, Matthew A. [Nexia Solutions Ltd., British Technology Centre, Sellafield, CA20 1PG (United Kingdom); Stephenson, Keith; Weston, Rebecca [Sellafield Ltd., B582, Sellafield, CA20 1PG (United Kingdom)

2007-07-01T23:59:59.000Z

303

Complexity of Homogeneous Co-Boolean Constraint Satisfaction Problems  

E-Print Network (OSTI)

Constraint Satisfaction Problems (CSP) constitute a convenient way to capture many combinatorial problems. The general CSP is known to be NP-complete, but its complexity depends on a template, usually a set of relations, upon which they are constructed. Following this template, there exist tractable and intractable instances of CSPs. It has been proved that for each CSP problem over a given set of relations there exists a corresponding CSP problem over graphs of unary functions belonging to the same complexity class. In this short note we show a dichotomy theorem for every finite domain D of CSP built upon graphs of homogeneous co-Boolean functions, i.e., unary functions sharing the Boolean range {0, 1}.

Richoux, Florian

2010-01-01T23:59:59.000Z

304

Markovian Search Games in Heterogeneous Spaces  

SciTech Connect

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

Griffin, Christopher H [ORNL

2009-01-01T23:59:59.000Z

305

Development of Advanced Massive Heterogeneous Sensor Networks  

NLE Websites -- All DOE Office Websites (Extended Search)

Advanced Massive Heterogeneous Sensor Networks Research Team * Doug McCorkle * Kris Bryden * Mark Bryden Ames Laboratory U of Maryland * Ashwani Gupta * Miao Yu Power Plant Challenges * Conflicting goals of reliable low cost energy and climate change mitigation * Large investment in current infrastructure * Little implementation of information technologies Sensors ... * will be "free" * will be small (lick 'n stick) * will be smart * will be ubiquitous Low cost improvements in sensing for control and condition monitoring can result in big improvements in cost and carbon emissions * "... develop the understandings, algorithms, and control strategies needed to utilize large-scale, high- density sensor networks in advanced power plants." * Develop techniques for the

306

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

SciTech Connect

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

307

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 was heated to 62.5 and 79.5'C and homogenized using a Rannie Model 12.51H double stage homogenizer. The difference in whiteness between unhomogenized milk and homogenized milk was significant. Homogenization appeared to have a slight effect on the viscosity of milk. Homogenization increased the temperature of milk an average of 3'C ?1.5'C per 17.2 MPa. Increasing homogenizing pressure at 62.5'C reduced fat globule size which was reflected in the reduction of the volume surface average diameter and tenth percentile parameter and increased specific surface area. Homogenization was most effective between 0 and 58.6 MPa. This was confirmed by the rate of reduction of volume to surface average diameter and in the rapid increase in specific surface area. Double stage homogenization reduced particle size compared with single stage homogenization. Homogenizing at 79.50C produced clumping and coalescence of fat globules at pressures greater than 58.6 MPa. This effect was observed as increased volume surface average diameter, changes in the tenth and ninetieth percentile parameters and as a decrease in specific surface area. An increase in particle size due to double stage homogenization was observed when milk was homogenized at pressures greater than 72.4 MPa.

Gonzalez De Cossio, Carlos

1994-01-01T23:59:59.000Z

308

Effects of Porous Medium Heterogeneity on Vadose Zone Desiccation: Intermediate-scale Laboratory Experiments and Simulations  

Science Conference Proceedings (OSTI)

Soil desiccation (drying), involving water evaporation induced by dry gas injection, is a potentially robust vadose zone remediation process to limit contaminant transport through the vadose zone. A series of four intermediate-scale flow cell experiments was conducted in homogeneous and simple layered heterogeneous porous medium systems to investigate the effects of heterogeneity on desiccation of unsaturated porous media. The permeability ratios of porous medium layers ranged from about five to almost two orders of magnitude. The insulated flow cell was equipped with twenty humidity and temperature sensors and a dual-energy gamma system was used to determine water saturations at various times. The multiphase code STOMP was used to simulate the desiccation process. Results show that injected dry gas flowed predominantly in the higher permeability layer and delayed water removal from the lower permeability material. For the configurations tested, water vapor diffusion from the lower to the higher permeability zone was considerable over the duration of the experiments, resulting in much larger relative humidity values of the outgoing air than based on permeability ratios alone. Acceptable numerical matches with the experimental data were obtained when an extension of the saturation-capillary pressure relation below the residual water saturation was used. The agreements between numerical and experimental results suggest that the correct physics are implemented in the simulator and that the thermal and hydraulic properties of the porous media, flow cell wall and insulation materials were properly represented.

Oostrom, Martinus; Freedman, Vicky L.; Wietsma, Thomas W.; Dane, Jacob H.; Truex, Michael J.

2012-11-01T23:59:59.000Z

309

IRON-60 HETEROGENEITY AND INCOMPLETE ISOTOPE MIXING IN THE EARLY SOLAR SYSTEM  

SciTech Connect

Short-lived radionuclides (e.g., {sup 26}Al, {sup 53}Mn, {sup 60}Fe, {sup 182}Hf) are widely used to refine the chronology of the early solar system. They provide chronological information, however, only if they were homogeneously distributed in the source region of the objects under scrutiny at the time of their formation. With the high level of precision now achieved on isotopic measurements, very short time intervals can in principle be resolved and a precise evaluation of the initial homogeneity degree becomes increasingly crucial. High-precision nickel isotope data for differentiated meteorites (angrites, ureilites) and chondritic (CB) components allow us to test the initial distribution of radioactive {sup 60}Fe and stable Ni isotopes. Although these meteorites appear to have formed nearly contemporaneously, they yield variable initial {sup 60}Fe/{sup 56}Fe ratios. Besides, the CB metal nodules and ureilite silicates show nucleosynthetic anomalies. The new data presented here do not confirm the recently inferred late injection of {sup 60}Fe into the protoplanetary disk. Instead, live {sup 60}Fe was present, but heterogeneously distributed, from the start of the solar system, revealing an incomplete mixing of material from various nucleosynthetic sources and restricting the use of the {sup 60}Fe-{sup 60}Ni system as a chronometer.

Quitte, Ghylaine [Universite de Lyon (France); Markowski, Agnes [ETH Zurich, Institute for Isotope Geology and Mineral Resources, Clausiusstrasse 25, CH-8092 Zurich (Switzerland); Latkoczy, Christopher [ETH Zurich, D-CHAB, Laboratory of Inorganic Chemistry, Wolfgang-Pauli Strasse 10, CH-8093 Zurich (Switzerland); Gabriel, Aron; Pack, Andreas, E-mail: Ghylaine.Quitte@ens-lyon.f [Geowissenschaftliches Zentrum, Universitaet Goettingen, Goldschmidtstrasse 1, D-37077 Goettingen (Germany)

2010-09-10T23:59:59.000Z

310

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

SciTech Connect

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

311

Estimating stress heterogeneity from aftershock rate  

E-Print Network (OSTI)

We estimate the rate of aftershocks triggered by a heterogeneous stress change, using the rate-and-state model of Dieterich [1994]. We show than an exponential stress distribution P(\\tau)~ exp(-\\tau/\\tau_0) gives an Omori law decay of aftershocks with time ~1/t^p, with an exponent p=1-A\\sigma_n/\\tau_0, where A is a parameter of the rate-and-state friction law, and \\sigma_n the normal stress. Omori exponent p thus decreases if the stress "heterogeneity" \\tau_0 decreases. We also invert the stress distribution P(\\tau) from the seismicity rate R(t), assuming that the stress does not change with time. We apply this method to a synthetic stress map, using the (modified) scale invariant "k^2" slip model [Herrero and Bernard, 1994]. We generate synthetic aftershock catalogs from this stress change. The seismicity rate on the rupture area shows a huge increase at short times, even if the stress decreases on average. This stochastic slip model gives a Gaussian stress distribution, but nevertheless produces an aftersho...

Helmstetter, A; Helmstetter, Agnes; Shaw, Bruce E.

2005-01-01T23:59:59.000Z

312

Event Model Interfaces for Heterogeneous System Analysis  

E-Print Network (OSTI)

Complex embedded systems consist of hardware and software components from different domains, such as control and signal processing, many of them supplied by different IP vendors. The embedded system designer faces the challenge to integrate, optimize and verify the resulting heterogeneous systems. While formal verification is available for some subproblems, the analysis of the whole system is currently limited to simulation or emulation. In this paper, we tackle the analysis of global resource sharing, scheduling, and buffer sizing in heterogeneous embedded systems. For many practically used preemptive and non-preemptive hardware and software scheduling algorithms of processors and busses, semi-formal analysis techniques are known. However, they cannot be used in system level analysis due to incompatibilities of their underlying event models. This paper presents a technique to couple the analysis of local scheduling strategies via an event interface model. We derive transformation rules between the most important event models and provide proofs where necessary. We use expressive examples to illustrate their application.

Kai Richter; Rolf Ernst

2002-01-01T23:59:59.000Z

313

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

Science Conference Proceedings (OSTI)

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

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

2012-09-25T23:59:59.000Z

314

Hydrogen and methane syntheses through radiation catalysis. Progress report, June 1, 1977--August 31, 1978  

DOE Green Energy (OSTI)

Preliminary testing was performed of the concept of an electronic theory of catalysis to relate electrical properties of the catalysts to increased rates in radiation-induced reactions. The first system selected for study was the radiolysis of water as stimulated by absorption of gamma radiation, a system that has been thoroughly tested by numerous workers all in excellent agreement. Early results indicate a significant correspondence between hydrogen gas yield and the forbidden band gap (Eg) of the catalyst substrate, when Eg approximates the energy of the hydrogen-oxygen bond in the water molecule. Catalysts tested were TiO/sub 2/, SrTiO/sub 3/, Sb/sub 2/O/sub 3/, MoO/sub 3/, Nb/sub 2/O/sub 5/, SnO/sub 2/, CaO, HfO/sub 2/, In/sub 2/O/sub 3/, and V/sub 2/O/sub 5/. Equipment to measure dielectric properties of solids has been built and calibrated, and will now be applied to pre- and post-irradiation testing of the catalysts used. Separate abstracts were prepared for the appendices: one a review of existing analytical models of photoelectrochemical cells and the other a theoretical modeling of semiconductor-electrolyte interfaces.

Morse, J G

1978-09-01T23:59:59.000Z

315

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

Science Conference Proceedings (OSTI)

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

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

2011-05-24T23:59:59.000Z

316

THE EFFECT OF SULFUR ON METHANE PARTIAL OXIDATION AND REFORMING PROCESSES FOR LEAN NOX TRAP CATALYSIS  

Science Conference Proceedings (OSTI)

Lean NOx trap catalysis has demonstrated the ability to reduce NOx emissions from lean natural gas reciprocating engines by >90%. The technology operates in a cyclic fashion where NOx is trapped on the catalyst during lean operation and released and reduced to N2 under rich exhaust conditions; the rich cleansing operation of the cycle is referred to as "regeneration" since the catalyst is reactivated for more NOx trapping after NOx purge. Creating the rich exhaust conditions for regeneration can be accomplished by catalytic partial oxidation of methane in the exhaust system. Furthermore, catalytic reforming of partial oxidation exhaust can enable increased quantities of H2 which is an excellent reductant for lean NOx trap regeneration. It is critical to maintain clean and efficient partial oxidation and reforming processes to keep the lean NOx trap functioning properly and to reduce extra fuel consumption from the regeneration process. Although most exhaust constituents do not impede partial oxidation and reforming, some exhaust constituents may negatively affect the catalysts and result in loss of catalytic efficiency. Of particular concern are common catalyst poisons sulfur, zinc, and phosphorous. These poisons form in the exhaust through combustion of fuel and oil, and although they are present at low concentrations, they can accumulate to significant levels over the life of an engine system. In the work presented here, the effects of sulfur on the partial oxidation and reforming catalytic processes were studied to determine any durability limitations on the production of reductants for lean NOx trap catalyst regeneration.

Parks, II, James E [ORNL; Ponnusamy, Senthil [ORNL

2006-01-01T23:59:59.000Z

317

Steam catalysis in CaO carbonation under low steam partial pressure  

Science Conference Proceedings (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

318

Advances in Synthesis and Densification of Heterogeneous Materials  

Science Conference Proceedings (OSTI)

Advances in Current Activated Tip-Based Sintering (CATS) · Advances in Synthesis and Densification of Heterogeneous Materials · Application of Metal Injection ...

319

Structural and Chemical Heterogeneities of Ultrafine Eutectic Alloys  

Science Conference Proceedings (OSTI)

Based on these investigaions, it is possible to systematically categorize the influence of structural and chemical heterogeneities on deformation behavior of the ...

320

The Influence of Reservoir Heterogeneity on Geothermal Fluid...  

NLE Websites -- All DOE Office Websites (Extended Search)

Alliance for Sustainable Energy, LLC. THE INFLUENCE OF RESERVOIR HETEROGENEITY ON GEOTHERMAL FLUID AND METHANE RECOVERY FROM A GEOPRESSURED GEOTHERMAL RESERVOIR Ariel Esposito...

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

On the Numerical Simulation of Waterflooding of Heterogeneous Petroleum Reservoirs  

E-Print Network (OSTI)

We present a new, naturally parallelizable, accurate numerical method for the solution of transport-dominated diffusion processes in heterogeneous porous media.

Jim Douglas, Jr.; Frederico Furtado; Felipe Pereira

1997-01-01T23:59:59.000Z

322

Modeling of homogeneous charge compression ignition (HCCI) of methane  

DOE Green Energy (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

323

Gravitational lensing in plasma: Relativistic images at homogeneous plasma  

E-Print Network (OSTI)

We investigate the influence of plasma presence on relativistic images formed by Schwarzschild black hole lensing. When a gravitating body is surrounded by a plasma, the lensing angle depends on a frequency of the electromagnetic wave due to refraction properties, and the dispersion properties of the light propagation in gravitational field in plasma. The last effect leads to difference, even in uniform plasma, of gravitational deflection angle in plasma from vacuum case. This angle depends on the photon frequency, what resembles the properties of the refractive prism spectrometer. Here we consider the case of a strong deflection angle for the light, traveling near the Schwarzschild black hole, surrounded by a uniform plasma. Asymptotic formulae are obtained for the case of a very large deflection angle, exceeding $2\\pi$. We apply these formulae for calculation of position and magnification of relativistic images in a homogeneous plasma, which are formed by the photons performing one or several revolutions around the central object. We conclude that the presence of the uniform plasma increases the angular size of relativistic rings or the angular separation of point images from the gravitating center. The presence of the uniform plasma increases also a magnification of relativistic images. The angular separation and the magnification become significantly larger than in the vacuum case, when the photon frequency goes to a plasma frequency.

Oleg Yu. Tsupko; Gennady S. Bisnovatyi-Kogan

2013-05-30T23:59:59.000Z

324

Charecterization of inertial and pressure effects in homogeneous turbulence  

E-Print Network (OSTI)

The objective of the thesis is to characterize the linear and nonlinear aspects of inertial and pressure effects in turbulent flows. In the first part of the study, computations of Navier-Stokes and 3D Burgers equations are performed in the rapid distortion (RD) limit to analyze the inviscid linear processes in homogeneous turbulence. By contrasting the results of Navier- Stokes RD equations and Burgers RD equations, the effect of pressure can be isolated. The evolution of turbulent kinetic energy and anisotropy components and invariants are examined. In the second part of the thesis, the velocity gradient dynamics in turbulent flows are studied with the help of inviscid 3D Burgers equations and restricted Euler equations. The analytical asymptotic solutions of velocity gradient tensor are obtained for both Burgers and restricted Euler equations. Numerical computations are also performed to identify the stable solutions. The results are compared and contrasted to identify the effect of pressure on nonlinear velocity gradient dynamics. Of particular interest are the sign of the intermediate principle strain-rate and tendency of vorticity to align with the intermediate principle strain-rate. These aspects of velocity gradients provide valuable insight into the role of pressure in the energy cascade process.

Bikkani, Ravi Kiran

2005-08-01T23:59:59.000Z

325

Automated resolution of semantic heterogeneity in multidatabases  

Science Conference Proceedings (OSTI)

A multidatabase system provides intergrated access to heterogeneous, autonomous local databases in a distributed system. An important problem in current multidatabase systems is identification of semantically similar data in different local databases. The Summary Schemas Model (SSM) is proposed as an extension to multidatabase systems to aid in semantic identification. The SSM uses a global data structure to abstract the information available in a multidatabase system. This abstracted form allows users to use their own terms. The system uses the global data structure to match the user`s terms to the semantically closest available system terms. A simulation of the SSM is presented to compare imprecise-query processing with corresponding query-processing costs in a standard multidatabase system. The costs and benefits of the SSM are discussed, and future research directions are presented. 57 refs., 15 figs.

Bright, M.W. [IBM Federal Systems Company, Gaithersburg, MD (United States); Hurson, A.R.; Pakzad, S. [Pennsylvania State Univ., University Park, PA (United States)

1994-06-01T23:59:59.000Z

326

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)

cross-sectional perspective, at least, recent developments in household-surveys have improved the quantity and quality of the data substantially (for example, LIS, 2010; SEDLAC, 2010; WIDER, 2008; World Bank, 2010). The World Development Indicators... countries of the oil-producing Middle East (for which there are no data) share the inequality heights of the latter group).18 This uniqueness of Latin American and Southern African is crucial for the testing of the “Inverted-U”.19 If these two regions...

Palma, José Gabriel

2011-01-26T23:59:59.000Z

327

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

328

A homogenous combustion catalyst for fuel efficiency improvements in diesel engines fuelled with diesel and biodiesel.  

E-Print Network (OSTI)

??[Truncated abstract] The ferrous picrate based homogeneous combustion catalyst has been claimed to promote diesel combustion and improve fuel efficiency in diesel engines. However, the… (more)

Zhu, Mingming

2012-01-01T23:59:59.000Z

329

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

330

Microwave-Assisted Heterogeneous Catalytic Transesterification of Soybean Oil  

Science Conference Proceedings (OSTI)

Biodiesel, as a renewable bioenergy, recently has been researched in regard to biodiesel products. In this study, soybean oil was converted to biodiesel with methanol using several heterogeneous catalysts, furthermore, the process by means of microwave ... Keywords: Biodiesel, Transesterification, Microwave, Heterogeneous

Ming-Chien Hsiao; Pei-Hung Liao; Hsiu-Ling Hsu

2012-06-01T23:59:59.000Z

331

Three-phase immiscible displacement in heterogeneous petroleum reservoirs  

Science Conference Proceedings (OSTI)

We describe a fractional-step numerical procedure for the simulation of immiscible three-phase flow in heterogeneous porous media that takes into account capillary pressure and apply it to indicate the existence of a so-called "transitional" wave in ... Keywords: central difference scheme, heterogeneous reservoirs, mixed finite elements, operator splitting, three-phase flow

E. Abreu; J. Douglas, Jr.; F. Furtado; D. Marchesin; F. Pereira

2006-11-01T23:59:59.000Z

332

Analysis of gravitational wave signals on heterogeneous architectures  

Science Conference Proceedings (OSTI)

Heterogeneous architectures and programming techniques will be very important in the development of exascale HPC applications. Adapting heterogeneous programming techniques to scientific programming is not always straightforward. Here we present an in-depth ... Keywords: gravitational waves, hybrid computing, parallel computations

Maciej Cytowski

2010-06-01T23:59:59.000Z

333

Processor virtualization and split compilation for heterogeneous multicore embedded systems  

Science Conference Proceedings (OSTI)

Embedded multiprocessors have always been heterogeneous, driven by the power-efficiency and compute-density of hardware specialization. We aim to achieve portability and sustained performance of complete applications, leveraging diverse programmable ... Keywords: annotations, back-end optimization, bytecode language, heterogeneous multicore, portable performance, specialization, split compilation, vectorization, virtualization

Albert Cohen; Erven Rohou

2010-06-01T23:59:59.000Z

334

Power-efficient time-sensitive mapping in heterogeneous systems  

Science Conference Proceedings (OSTI)

Heterogeneous systems that contain multiple types of resources, such as CPUs and GPUs, are becoming increasingly popular thanks to the potential of achieving high performance and energy efficiency. In such systems, the problem of data mapping and communication ... Keywords: heterogeneous cpu/gpu multiprocessors, multi-core architectures, power-efficient scheduling

Cong Liu; Jian Li; Wei Huang; Juan Rubio; Evan Speight; Xiaozhu Lin

2012-09-01T23:59:59.000Z

335

Tarazu: optimizing MapReduce on heterogeneous clusters  

Science Conference Proceedings (OSTI)

Data center-scale clusters are evolving towards heterogeneous hardware for power, cost, differentiated price-performance, and other reasons. MapReduce is a well-known programming model to process large amount of data on data center-scale clusters. Most ... Keywords: MapReduce, cluster scheduling, heterogeneous clusters, load imbalance, shuffle

Faraz Ahmad; Srimat T. Chakradhar; Anand Raghunathan; T. N. Vijaykumar

2012-04-01T23:59:59.000Z

336

Transport over heterogeneous networks using the RINA architecture  

Science Conference Proceedings (OSTI)

The evolution of various wireless technologies has greatly increased the interest in heterogeneous networks, in which the mobile users can enjoy services while roaming between different networks. The current Internet architecture does not seem to cope ... Keywords: data transport, hand-offs, heterogeneous networks, mobility, recursive inter-network architecture (RINA)

Eleni Trouva; Eduard Grasa; John Day; Ibrahim Matta; Lubomir T. Chitkushev; Steve Bunch; Miguel Ponce de Leon; Patrick Phelan; Xavier Hesselbach-Serra

2011-06-01T23:59:59.000Z

337

Engineering complex adaptations in highly heterogeneous distributed systems  

Science Conference Proceedings (OSTI)

Distributed systems now encounter extreme heterogeneity in the form of diverse devices, network types etc., and also need to dynamically adapt to changing environmental conditions. Self-adaptive middleware is ideally situated to address these challenges. ... Keywords: adaptation, heterogeneity, middleware, reflection

Paul Grace; Gordon S. Blair; Carlos Flores Cortes; Nelly Bencomo

2008-09-01T23:59:59.000Z

338

A dynamic self-scheduling scheme for heterogeneous multiprocessor architectures  

Science Conference Proceedings (OSTI)

Today's heterogeneous architectures bring together multiple general-purpose CPUs and multiple domain-specific GPUs and FPGAs to provide dramatic speedup for many applications. However, the challenge lies in utilizing these heterogeneous processors to ... Keywords: Dynamic self-scheduling, FPGAs, GP-GPUs, workload balancing

Mehmet E. Belviranli; Laxmi N. Bhuyan; Rajiv Gupta

2013-01-01T23:59:59.000Z

339

An Ontology-Based Method for Integrating Heterogeneous Itembanks  

Science Conference Proceedings (OSTI)

In this paper, we present a simple but efficient algorithm for integrating a collection of heterogeneous itembanks, called Heterogeneous Itembanks Integrator (HIBI). This algorithm is motivated by the desire to integrate itembanks provided by publishers ... Keywords: Itembanks, e-Learning System, and ontology

Chun-Wei Tsai; Shih-Pang Tseng; Yu-Sheng Yang; Ming-Chao Chiang; Chu-Sing Yang

2009-11-01T23:59:59.000Z

340

Handover strategy of smart mobile terminals among heterogeneous wireless networks  

Science Conference Proceedings (OSTI)

Due to the variety of wireless networks, the handover among heterogeneous wireless networks has become a research hotspot in recent years. More attention have been paid to the radio access network and the core network than the terminal side. In the future ... Keywords: heterogeneous wireless network, network handover, network handover design, smart mobile terminal

Wei Lin; Weiqiang Wu; Qinyu Zhang

2008-07-01T23:59:59.000Z

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

com  

Science Conference Proceedings (OSTI)

... in small molecules' storage, separation, purification and sensing, in enantioselective separation and asymmetric heterogeneous catalysis. ...

342

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

SciTech Connect

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

Stuart L. Soled and Nancy Ryan Gray

2009-01-01T23:59:59.000Z

343

Supported organometallic complexes: Surface chemistry, spectroscopy, and catalysis. Progress report, February 1, 1991--January 31, 1992  

SciTech Connect

The long-range goal of this project is to elucidate and understand the surface chemistry and catalytic properties of well-defined, highly-reactive organometallic molecules (principally based upon abundant actinide, lanthanide, and early transition elements) adsorbed on metal oxides and halides. The nature of the adsorbed species is probed by a battery of chemical and physicochemical techniques, to understand the nature of the molecular-surface coordination chemistry and how this can give rise to extremely high catalytic activity. A complementary objective is to delineate the scope and mechanisms of the heterogeneous catalytic reactions, as well as to relate them both conceptually and functionally to model systems generated in solution.

Marks, T.J.

1992-02-01T23:59:59.000Z

344

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

SciTech Connect

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

345

Simple SQP approach for out-of-plane loaded homogenized brickwork panels, accounting for softening  

Science Conference Proceedings (OSTI)

A simple homogenized model for the non linear analysis of masonry walls out-of-plane loaded is presented. In the model, the panels are assumed to behave as Kirchhoff-Love plates. A rectangular running bond elementary cell (RVE) is subdivided into several ... Keywords: Homogenization, Masonry, Out-of-plane loads, Quadratic programming

Gabriele Milani; Antonio Tralli

2011-01-01T23:59:59.000Z

346

Bulk viscous fluid hypersurface - homogeneous cosmological models with time varying G and ?  

Science Conference Proceedings (OSTI)

Hypersurface - homogeneous cosmological models containing a bulk viscous fluid with time varying G and ? have been presented. We have shown that the field equations are solvable for any arbitrary cosmic scale function. The viscosity coefficient ... Keywords: bulk viscosity, hypersurface - homogeneous, variable G and ?. LATEX

Shri Ram; M. K. Verma

2010-02-01T23:59:59.000Z

347

Computational study of homogeneous and stratified combustion in a compressed natural gas direct injection engine  

Science Conference Proceedings (OSTI)

In recent years, the type of combustion occurred within engine cylinder plays an important role determining the performance and emissions. In the present study, the computational investigation was performed in order to compare characteristics of homogeneous ... Keywords: compressed natural gas, direct injection, exhaust emissions, homogeneous combustion, stratified combustion

S. Abdullah; W. H. Kurniawan; M. A. Al-Rawi; Y. Ali; T. I. Mohamad

2009-02-01T23:59:59.000Z

348

Development of a predictive kinetic model for homogeneous Hg oxidation data  

Science Conference Proceedings (OSTI)

Several researchers have developed kinetic models to predict the effects of various flue gas components on homogeneous mercury (Hg) oxidation. Most of these models make use of over 50 reversible reactions that involve radicals in a combustion or post-combustion ... Keywords: Chlorine gas, Homogeneous mercury oxidation, Kinetic model, Simulated flue gas

Hans Agarwal; Harvey G. Stenger

2007-01-01T23:59:59.000Z

349

Comparison of homogenized and enhanced diffusion solutions of model PWR problems  

SciTech Connect

Model problem comparisons in slab geometry are made between two forms of homogenized diffusion theory and enhanced diffusion theory. The pin-cell discontinuity factors for homogenized diffusion calculations are derived from homogenized variational nodal P1 response matrices and from standard finite differencing. Enhanced diffusion theory consists of applying quasi-reflected interface conditions to reduce variational nodal Pn response matrices to one degree of freedom per interface, without homogenization within the cell. As expected both homogenized diffusion methods preserve reaction rates exactly if the discontinuity factors are derived from the P 11 reference solutions. If no reference lattice solution is available, discontinuity factors may be approximated from single cells with reflected boundary conditions; the computational effort is then comparable to calculating the enhanced diffusion response matrices. In this situation enhanced diffusion theory gives the most accurate results and finite difference discontinuity factors the least accurate. (authors)

Lewis, E. E. [Dept. of Mechanical Engineering, Northwestern Univ., 2145 Sheridan Rd., Evanston, IL 60208 (United States); Smith, M. A. [Nuclear Engineering Div., Argonne National Laboratory, 9700 S. Cass Ave, Argonne, IL 60439 (United States)

2012-07-01T23:59:59.000Z

350

Evaluation of the adequacy of using few-group lattice-homogenized properties for the diffusion analysis of the super critical water reactor  

SciTech Connect

Two issues may affect the accuracy of computed core reactivities and flux/power distributions for the Super Critical Water Reactor (SCWR) core with traditional core-analysis code RFSP: one is the two-energy-group neutron-diffusion theory; the other is the generation of lattice-homogenized properties with the lattice code based on the single-lattice-cell model without considering the effects of the environment. These two issues are not SCWR specific; however their effect may be more significant for SCWR. It has been illustrated that the lattice-homogenized properties calculated with the single-lattice-cell model is not sufficiently accurate for heterogeneous core configurations such as ACR-1000 checkerboard-voiding and core-reflector interface when adjacent channels experience significant spectrum interaction. To evaluate the adequacy of using two-group neutron-diffusion theory with single-lattice-based lattice properties for the analysis of the SCWR core, a 2-D SCWR benchmark problem was setup with the reference solution provided by the continuous-energy Monte-Carlo code SERPENT. The assessment shows that the traditional two-group neutron-diffusion theory with the single-lattice-cell- based lattice properties is not sufficient to capture either the spectral change or the environment effect for the SCWR core. The solution of the eight-group neutron-diffusion equation with the multicell- based lattice properties is considered appropriate for the analysis of the d SCWR core. (authors)

Shen, W. [Candu Energy Inc., 2285 Speakman Dr., Mississauga, ON L5B 1K (Canada)

2012-07-01T23:59:59.000Z

351

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 condition for decarboxylative Claisen condensation in polyketide biosynthesis was discovered. The reaction of a malonic acid half oxyester with a Nhydroxysuccinmidyl ester forming reagent resulted in self-condensation to provide the corresponding 1,3-acetonedicarboxylic acid diester in the absence of a divalent metal chelator or a coordinating solvent. The decarboxylative Claisen condensation of malonyl adenosine using a poly-U template in solution or with immobilized poly-U was attempted. Various analytical methods demonstrated that malonyl adenosine underwent an exclusive hydrolysis reaction instead of condensation in the given conditions. Similar results were observed for the reaction of malonyl-CoA with acetyl-CoA on poly-U templates. No evidence for the decarboxylative Claisen condensation was observed by a DNA-templated system although a double helical structure of DNA duplex was proven to facilitate a bimolecular reaction by offering a favorable proximity effect. Therefore, it seems that the unsuccessful condensation resulted not from the bad template effect but from the intrinsic properties of the decarboxylative Claisen condensation reaction itself. Two tRNA molecules loaded with a malonic acid were prepared by ligation of truncated tRNAs with malonylated dinucletides. Our initial attempts to probe carbon-carbon bond formation by subjecting malonylated tRNAs to the in vitro translational machinery were not successful. Novel carbon isosteres of ?-amino acids are suggested as a potential source of a more stable and reactive carbanion for future experiments. Isoprenoid conjugates of nucleoside 5??-diphosphates, which were proposed as either an initiator nucleotide or substrate molecule for in vitro selection of prenyl-transferase ribozyme were prepared by one step nucleophilic displacement reactions. A random DNA pool was constructed for selection of a ketosynthase ribozyme. A substrate bearing a biotin tag was prepared by one-step conjugation. Hig-tagged T7 RNA polymerase was expressed and purified for a large scale transcription reaction. In vitro transcription of the random DNA pool with a 5??-thiol modified GMP analogue as an initiator nucleotide produced a thiol-modified random RNA library.

Ryu, Youngha

2003-05-01T23:59:59.000Z

352

Asymptotic behavior of two-phase flows in heterogeneous porous media for capillarity depending only on space. II. Non-classical shocks to model oil-trapping  

E-Print Network (OSTI)

We consider a one-dimensional problem modeling two-phase flow in heterogeneous porous media made of two homogeneous subdomains, with discontinuous capillarity at the interface between them. We suppose that the capillary forces vanish inside the domains, but not on the interface. Under the assumption that the gravity forces and the capillary forces are oriented in opposite directions, we show that the limit, for vanishing diffusion, is not the entropy solution of the hyperbolic scalar conservation law. A non-classical shock occurs on the interface, modeling oil-trapping.

Cancès, Clément

2009-01-01T23:59:59.000Z

353

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

SciTech Connect

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

Farzad Rahnema

2009-11-12T23:59:59.000Z

354

Holey Random Walks: Optics of Heterogeneous Turbid Composites  

E-Print Network (OSTI)

We present a probabilistic theory of random walks in turbid media with non-scattering regions. It is shown that important characteristics such as diffusion constants, average step lengths, crossing statistics and void spacings can be analytically predicted. The theory is validated using Monte Carlo simulations of light transport in heterogeneous systems in the form of random sphere packings, and good agreement is found. The role of step correlations is discussed, and differences between unbounded and bounded systems are investigated. Our results are relevant to the optics of heterogeneous systems in general, and represent an important step forward in the understanding of media with strong (fractal) heterogeneity in particular.

Svensson, Tomas; Grisi, Marco; Savo, Romolo; Burresi, Matteo; Wiersma, Diederik S

2012-01-01T23:59:59.000Z

355

Data management in heterogeneous environments and its implications to CEDR  

Science Conference Proceedings (OSTI)

We investigate in this report the issue of data management across multiple pre-existing databases characterized by various degrees of heterogeneity. Different approaches to the problem of data management in heterogeneous environments are reviewed and their advantages and disadvantages are discussed. We examine in some detail the problem of schema integration involved in these approaches. We illustrate different aspects of data management in heterogeneous environments with examples from the Comprehensive Epidemiological Data Resource (CEDR) project, and conclude the report with recommendations for CEDR. These recommendations are summarized in this paper.

Markowitz, V.M.

1990-10-27T23:59:59.000Z

356

Heterogeneous Responses to Water Conservation Programs: The Case of Residential Users in Los Angeles  

E-Print Network (OSTI)

on welfare of water conservation programs (compensatingHeterogeneous Responses to Water Conservation Programs: TheHeterogeneous responses to water conservations programs: the

Hanemann, W. Michael; Nauges, Celine

2005-01-01T23:59:59.000Z

357

Towards a multifrontal QR factorization for heterogeneous architectures over runtime systems  

E-Print Network (OSTI)

, computer architectures for high performance computing have considerably evolved toward heterogeneous. An example of popular heterogeneous architectures widely adopted in the high performance computing domain

Uçar, Bora

358

A Heterogeneous Sodium Fast Reactor Designed to Transmute Minor Actinide Actinide Waste Isotopes into Plutonium Fuel  

Science Conference Proceedings (OSTI)

An axial heterogeneous sodium fast reactor design is developed for converting minor actinide waste isotopes into plutonium fuel. The reactor design incorporates zirconium hydride moderating rods in an axial blanket above the active core. The blanket design traps the active core’s axial leakage for the purpose of transmuting Am-241 into Pu-238. This Pu-238 is then co-recycled with the spent driver fuel to make new driver fuel. Because Pu-238 is significantly more fissile than Am-241 in a fast neutron spectrum, the fissile worth of the initial minor actinide material is upgraded by its preconditioning via transmutation in the axial targets. Because, the Am-241 neutron capture worth is significantly stronger in a moderated epithermal spectrum than the fast spectrum, the axial targets serve as a neutron trap which recovers the axial leakage lost by the active core. The sodium fast reactor proposed by this work is designed as an overall transuranic burner. Therefore, a low transuranic conversion ratio is achieved by a degree of core flattening which increases axial leakage. Unlike a traditional “pancake” design, neutron leakage is recovered by the axial target/blanket system. This heterogeneous core design is constrained to have sodium void and Doppler reactivity worth similar to that of an equivalent homogeneous design. Because minor actinides are irradiated only once in the axial target region; elemental partitioning is not required. This fact enables the use of metal targets with electrochemical reprocessing. Therefore, the irradiation environment of both drivers and targets was constrained to ensure applicability of the established experience database for metal alloy sodium fast reactor fuels.

Samuel E. Bays

2011-02-01T23:59:59.000Z

359

EA-1790: Construction and Operation of a Heterogeneous Feed Biorefinery  

Energy.gov (U.S. Department of Energy (DOE)) Indexed Site

EA-1790: Construction and Operation of a Heterogeneous Feed EA-1790: Construction and Operation of a Heterogeneous Feed Biorefinery Enerkem Corporation Pontotoc, MS EA-1790: Construction and Operation of a Heterogeneous Feed Biorefinery Enerkem Corporation Pontotoc, MS SUMMARY The U.S. Department of Energy (DOE or the Department) is proposing to provide cost share funding to Enerkem, Inc (Enerkem) for the final design, construction, and operation of a proposed Heterogeneous Feed Biorefinery Project to be located in Pontotoc, Mississippi (hereafter referred to as the biorefinery or the proposed project). The biorefinery would use the dried and post-sorted biomass fraction of municipal solid waste (MSW) and wood biomass as feedstock. Enerkem's biorefinery would produce approximately 10 million gallons (38 million liters) of ethanol per year

360

Addressing the Challenges of Aggregational and Temporal Ontological Heterogeneity  

E-Print Network (OSTI)

In this paper, we first identify semantic heterogeneities that, when not resolved, often cause serious data quality problems. We discuss the especially challenging problems of temporal and aggregational ontological ...

Zhu, Hongwei

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

Discrete Feature Approach for Heterogeneous Reservoir Production Enhancement  

Science Conference Proceedings (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

362

Approaches for Averaging Surface Parameters and Fluxes over Heterogeneous Terrain  

Science Conference Proceedings (OSTI)

Successful prediction of possible climate change depends on realistic parameterization of land surface processes in climate models. Such parameterizations must take appropriate account of the heterogeneities that are found in most earth surfaces. ...

A. Chehbouni; E. G. Njoku; J-P. Lhomme; Y. H. Kerr

1995-05-01T23:59:59.000Z

363

Dynamic sensor tasking in heterogeneous, mobile sensor networks  

E-Print Network (OSTI)

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

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

2005-01-01T23:59:59.000Z

364

Statistical abstraction and model-checking of large heterogeneous systems  

Science Conference Proceedings (OSTI)

We propose a new simulation-based technique for verifying applications running within a large heterogeneous system. Our technique starts by performing simulations of the system in order to learn the context in which the application is used. Then, it ...

Ananda Basu; Saddek Bensalem; Marius Bozga; Benoît Caillaud; Benoît Delahaye; Axel Legay

2010-06-01T23:59:59.000Z

365

Progress in Developing and Extending RM³ Heterogeneous Integration Technologies  

E-Print Network (OSTI)

This paper describes recent progress in a continuing program to develop and apply RM³ (recess mounting with monolithic metallization) technologies for heterogeneous integration. Particular emphasis is placed on the APB ...

Fonstad, Clifton G. Jr.

366

Laboratory Measurements of Heterogeneous Reactions on Sulfuric Acid Surfaces  

Science Conference Proceedings (OSTI)

Increasing evidence from field, modeling, and laboratory studies suggests that heterogeneous reactions on stratospheric sulfate aerosol particles may contribute to global ozone depiction. Using a Knudsen cell reactor technique, the authors have ...

Leah R. Williams; Jeffrey A. Manion; David M. Golden; Margaret A. Tolbert

1994-07-01T23:59:59.000Z

367

Grounding Analysis in Heterogeneous Soil Models: Application to Underground Substations  

E-Print Network (OSTI)

Grounding Analysis in Heterogeneous Soil Models: Application to Underground Substations Ignasi in forthcoming publications. Keywords-grounding analysis; earthing analysis, underground substations; I to a river (at substations next to hydroelectric dams), or the grounding system of a buried electrical

Colominas, Ignasi

368

Programming in Manticore, a heterogenous parallel functional language  

Science Conference Proceedings (OSTI)

The Manticore project is an effort to design and implement a new functional language for parallel programming. Unlike many earlier parallel languages, Manticore is a heterogeneous language that supports parallelism at multiple levels. Specifically, the ...

Matthew Fluet; Lars Bergstrom; Nic Ford; Mike Rainey; John Reppy; Adam Shaw; Yingqi Xiao

2009-05-01T23:59:59.000Z

369

Heterogeneity and dynamicity of clouds at scale: Google trace analysis  

Science Conference Proceedings (OSTI)

To better understand the challenges in developing effective cloud-based resource schedulers, we analyze the first publicly available trace data from a sizable multi-purpose cluster. The most notable workload characteristic is heterogeneity: in resource ...

Charles Reiss; Alexey Tumanov; Gregory R. Ganger; Randy H. Katz; Michael A. Kozuch

2012-10-01T23:59:59.000Z

370

Dynamic Mapping in Energy Constrained Heterogeneous Computing Systems  

Science Conference Proceedings (OSTI)

An ad hoc grid is a wireless heterogeneous computing environment without a fixed infrastructure. The wireless devices have different capabilities, have limited battery capacity, support dynamic voltage scaling, and are expected to be used for eight hours ...

Jong-Kook Kim; H. J. Siegel; Anthony A. Maciejewski; Rudolf Eigenmann

2005-04-01T23:59:59.000Z

371

Probabilistic search optimization and mission assignment for heterogeneous autonomous agents  

Science Conference Proceedings (OSTI)

This paper presents an algorithmic framework for conducting search and identification missions using multiple heterogeneous agents. Dynamic objects of type "neutral" or "target" move through a discretized environment. Probabilistic representation of ...

Timothy H. Chung; Moshe Kress; Johannes O. Royset

2009-05-01T23:59:59.000Z

372

Observations of Fluxes and Inland Breezes over a Heterogeneous Surface  

Science Conference Proceedings (OSTI)

Repeated aircraft runs at about 33 m over heterogeneous terrain are analyzed to study the spatial variability of the mesoscale flow and turbulent fluxes. An irrigated area, about 12 km across, generates a relatively cool moist inland breeze. As ...

L. Mahrt; Jielun Sun; Dean Vickers; J. I. Macpherson; J. R. Pederson; R. L. Desjardins

1994-09-01T23:59:59.000Z

373

Mobile identity management system in heterogeneous wireless networks  

Science Conference Proceedings (OSTI)

Heterogeneous wireless networks increasingly encroach on our lives. Various technologies and mobile applications more often than usual are now used by mobile users. Intensive development of mobile networks not only sets new standards for radio, but increasingly ...

?Ukasz Kucharzewski; Zbigniew Kotulski

2011-01-01T23:59:59.000Z

374

Tax compliance in a simulated heterogeneous multi-agent society  

Science Conference Proceedings (OSTI)

We consider an individualised approach to agent behaviour in an application to the classical economic problem of tax compliance. Most economic theories consider homogeneous representative agent utilitarian approaches to explain the decision of complying ...

Luis Antunes; João Balsa; Paulo Urbano; Luis Moniz; Catarina Roseta-Palma

2005-07-01T23:59:59.000Z

375

A Computational Approach to Homogenizing Nickel-Based Single Crystal Alloys  

NLE Websites -- All DOE Office Websites (Extended Search)

Computational Approach to Homogenizing Nickel-Based Computational Approach to Homogenizing Nickel-Based Single Crystal Alloys Contact NETL Technology Transfer Group techtransfer@netl.doe.gov May 2013 Significance * Provides significantly diminished processing costs, including reduced energy consumption and throughput times, and increased availability of capital equipment such as furnaces, due to shorter heat treatments * Generates superior Ni-based superalloys with improved performance in downstream applications * Provides extreme flexibility, allowing for modification to meet the differing constraints of individual production facilities and the level of homogenization desired

376

Homogeneity and Size Effects on the Liquid-Gas Coexistence Curve  

E-Print Network (OSTI)

The effects of (in)homogeneity and size on the phase diagram of Lennard-Jones fluids are investigated. It is shown that standard multifragmentation scenarios (finite equilibrated systems with conserved center of mass position and momentum) are implying a strong radial inhomogeneity of the system strongly affecting the phase diagram. The homogeneity constraint is therefore necessary for finite systems in order to align to the ``meaning'' of infinite systems phase diagrams. In this respect, a method which deduces the equation of state of homogeneous finite systems from the one corresponding to bulk matter is designed. The resultant phase diagrams show a strong dependence on the system's size.

Al. H. Raduta; Ad. R. Raduta

2003-01-13T23:59:59.000Z

377

Power management for heterogeneous clusters: An experimental study  

Science Conference Proceedings (OSTI)

Reducing energy consumption has a significant role in mitigating the total cost of ownership of computing clusters. Building heterogeneous clusters by combining high-end and low-end server nodes (e.g., Xeons and Atoms) is a recent trend towards achieving ... Keywords: Web server cluster, power management, heterogeneous cluster, energy consumption, high-end server nodes, low-end server nodes, Xeons, Atoms, energy-efficient computing, cluster-level power manager, optimal cluster configuration

M. Mustafa Rafique; Nishkam Ravi; Srihari Cadambi; Ali R. Butt; Srimat Chakradhar

2011-07-01T23:59:59.000Z

378

Cross section space shielding in double heterogeneous HTGR systems  

SciTech Connect

Collision probability methods using rational approximations for space shielding of cross sections in nuclear reactor codes allowing for one level of heterogeneity are first reviewed. A Dancoff factor for a cylindrical HTGR fuel pin with grain structure is then derived. A new simple method for cross section space shielding in a doubly heterogeneous HTGR system using collision probabilities and rational approximations is subsequently presented and calculations based on it are compared with calculations based on more elaborate methods. 39 references. (auth)

Stamatelatos, M.G.

1975-11-01T23:59:59.000Z

379

Beyond homogeneous decomposition: scaling long-range forces on Massively Parallel Systems  

Science Conference Proceedings (OSTI)

With supercomputers anticipated to expand from thousands to millions of cores, one of the challenges facing scientists is how to effectively utilize this ever-increasing number. We report here an approach that creates a heterogeneous decomposition by ...

D. F. Richards; J. N. Glosli; B. Chan; M. R. Dorr; E. W. Draeger; J.-L. Fattebert; W. D. Krauss; T. Spelce; F. H. Streitz; M. P. Surh; J. A. Gunnels

2009-11-01T23:59:59.000Z

380

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

DOE Green Energy (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

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

A New Homogenized Climate Division Precipitation Dataset for Analysis of Climate Variability and Climate Change  

Science Conference Proceedings (OSTI)

A new homogeneous climate division monthly precipitation dataset [based on full network estimated precipitation (FNEP)] was created as an alternative to the National Climatic Data Center (NCDC) climate division dataset. These alternative climate ...

D. Brent McRoberts; John W. Nielsen-Gammon

2011-06-01T23:59:59.000Z

382

Homogeneous Ice Nucleation and Supercooled Liquid Water in Orographic Wave Clouds  

Science Conference Proceedings (OSTI)

This study investigates ice nucleation mechanisms in cold lenticular wave clouds, a cloud type characterized by quasi-steady-state air motions and microphysical properties. It is concluded that homogeneous ice nucleation is responsible for the ...

Andrew J. Heymsfield; Larry M. Miloshevich

1993-08-01T23:59:59.000Z

383

A New Look at Homogeneous Ice Nucleation in Supercooled Water Drops  

Science Conference Proceedings (OSTI)

The classical theory for homogeneous ice nucleation in supercooled water is investigated in the light of recent data published in various physico-chemical journal on the physical properties of supercooled water and in the light of recent evidence ...

H. R. Pruppacher

1995-06-01T23:59:59.000Z

384

CMB temperature anisotropy from broken spatial isotropy due to a homogeneous cosmological magnetic field  

Science Conference Proceedings (OSTI)

We derive the cosmic microwave background temperature anisotropy two-point correlation function (including off-diagonal correlations) from broken spatial isotropy due to an arbitrarily oriented homogeneous cosmological magnetic field.

Kahniashvili, Tina [Department of Physics, Kansas State University, 116 Cardwell Hall, Manhattan, Kansas 66506 (United States); Department of Physics, Laurentian University, Ramsey Lake Road, Sudbury, ON P3E 2C6 (Canada); National Abastumani Astrophysical Observatory, 2A Kazbegi Ave, Tbilisi, GE-0160 (Georgia); Lavrelashvili, George [Department of Theoretical Physics, A. Razmadze Mathematical Institute, 1 M. Aleksidze, Tbilisi, GE-0193 (Georgia); Ratra, Bharat [Department of Physics, Kansas State University, 116 Cardwell Hall, Manhattan, Kansas 66506 (United States)

2008-09-15T23:59:59.000Z

385

Evaluation of the Effect of the Luers–Eskridge Radiation Adjustments on Radiosonde Temperature Homogeneity  

Science Conference Proceedings (OSTI)

The effect of the Luers–Eskridge adjustments on the homogeneity of archived radiosonde temperature observations is evaluated. Using unadjusted and adjusted radiosonde data from the Comprehensive Aerological Reference Dataset (CARDS) as well as ...

Imke Durre; Thomas C. Peterson; Russell S. Vose

2002-06-01T23:59:59.000Z

386

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

387

Modeling the Scattering of Light by Homogeneous Vegetation in Optical Remote Sensing  

Science Conference Proceedings (OSTI)

This paper discusses the problem of radiation transfer in geophysical media, in particular, within homogeneous plant canopies over terrestrial surfaces. The emphasis is placed on the specificities of this problem when it is addressed with the ...

Bernard Pinty; Michel M. Verstraete

1998-01-01T23:59:59.000Z

388

Homogeneous Condensation—Freezing Nucleation Rate Measurements for Small Water Droplets in an Expansion Cloud Chamber  

Science Conference Proceedings (OSTI)

Experimental data on ice nucleation, presented in an earlier paper, are analyzed to yield information about the homogeneous nucleation rate of ice from supercooled liquid and the heights of energy barriers to that nucleation. The experiment ...

Donald E. Hagen; Rodney J. Anderson; James L. Kassner Jr.

1981-06-01T23:59:59.000Z

389

A novel digital beamforming technique based on homogeneous adaptation employing time-varying convergence factors  

Science Conference Proceedings (OSTI)

In this paper, a novel complex homogeneous adaptation least mean square algorithm (complex HA-LMS) for digital beamforming is presented. The proposed technique independently adjusts the real and imaginary components of the complex adaptive filter coefficients ...

Raghuram Ranganathan; Wasfy Mikhael

2009-01-01T23:59:59.000Z

390

Quality Control and Homogeneity of Precipitation Data in the Southwest of Europe  

Science Conference Proceedings (OSTI)

A quality control process involving outliers processing, homogenization, and interpolation has been applied to 95 monthly precipitation series in the Iberian Peninsula, southern France, and northern Africa during the period 1899–1989. A detailed ...

J. Fidel González-Rouco; J. Luis Jiménez; Vicente Quesada; Francisco Valero

2001-03-01T23:59:59.000Z

391

Long-Term Free-Atmosphere Temperature Trends in China Derived from Homogenized In Situ Radiosonde Temperature Series  

Science Conference Proceedings (OSTI)

In this paper, radiosonde temperature time series (RTT) from 1958 to 2005 collected by the 116-station Chinese radiosonde network are examined. Quality control and homogenization are used to obtain a reliable RTT. The homogenization results ...

Yanjun Guo; Yihui Ding

2009-02-01T23:59:59.000Z

392

Homogenization of the Global Radiosonde Temperature Dataset through Combined Comparison with Reanalysis Background Series and Neighboring Stations  

Science Conference Proceedings (OSTI)

This article describes progress in the homogenization of global radiosonde temperatures with updated versions of the Radiosonde Observation Correction Using Reanalyses (RAOBCORE) and Radiosonde Innovation Composite Homogenization (RICH) software ...

Leopold Haimberger; Christina Tavolato; Stefan Sperka

2012-12-01T23:59:59.000Z

393

Binary Homogeneous Nucleation: Temperature and Relative Humidity Fluctuations, Nonlinearity, and Aspects of New Particle Production in the Atmosphere  

Science Conference Proceedings (OSTI)

Binary homogeneous nucleation of sulfuric acid and water vapor is thought to be the primary source of new particles in the marine atmosphere. The rate of binary homogeneous nucleation depends strongly on temperature and the gas-phase ...

Richard C. Easter; Leonard K. Peters

1994-07-01T23:59:59.000Z

394

Recovering a time-homogeneous stock price process from perpetual option prices  

E-Print Network (OSTI)

It is well-known how to determine the price of perpetual American options if the underlying stock price is a time-homogeneous diffusion. In the present paper we consider the inverse problem, i.e. given prices of perpetual American options for different strikes we show how to construct a time-homogeneous model for the stock price which reproduces the given option prices.

Ekstrom, Erik

2009-01-01T23:59:59.000Z

395

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-catalyzed reactions. The key to successfully achieving the desired reactivity is the ability to rationally tether the targeted organic functionality onto the OMS surface. Understanding the organic-inorganic interface is crucial for rational design of heterogeneous catalysts, because the local structure and molecule dynamics are paramount in determining the reactivity of the organic groups attached to the OMS surface. This dissertation focuses on three goals that will lead to a description of the organic-OMS interface and designing hybrid catalysts: 1) Determining the dynamics of organic groups attached to the OMS surface, 2) Catalytic testing to understand how the local structure and dynamics of the organic moiety influence the catalytic properties of organic-OMS catalysts, 3) Designing more active hybrid catalysts by introducing higher loadings of organic group using dendrimer structures. Solid-state NMR is uniquely suited for quantifying dynamics in the milli- to nano-second time scale. Deuterium (2H) NMR is a powerful tool to obtain detailed information about the dynamics or organic molecules. In this study, several simple functional groups isotopically labeled with deuterium have been attached to MCM-41 and SBA-15. The spectra display different molecular motions for different organic moieties. The results have indicated that the interactions between the functional groups and silanol groups on the surface influence the mobility of the organic fragments. Also, the porosity of the solid supports effects dynamics via confinement. The catalytic properties of simple amine groups attached to MCM-41, containing primary, secondary, and tertiary amines have been compared in the Nitroaldol (Henry) reaction. The effects of amine identity, structure, loading, presence of surface silanols, and the substrate topology on the catalytic properties have been investigated. The dramatic decrease of the activity of amine-functionalized MCM-41 by capping the residual silanol groups with hexamethyldisilazane was ascribed to the decrease of the interactions of hydrogen bonding between the amine functional groups and surface silanols. The result was consistent with the changes of the molecular motions shown by 2H NMR measurements. Fabricating OMS hybrid materials with high densities of organic functional groups leads to challenges in realizing uniform, catalytically active sites. Our group has immobilized melamine-based dendrimers on the surfaces of amine-functionalized SBA-15 materials by iterative synthesis procedures. The current studies in this dissertation mainly describe the catalytic properties of these dendrimers on SBA-15 and MCM-41 in the Nitroaldol (Henry) reaction, the transesterification reaction of triglycerides and methanol to synthesize methyl esters, and the cross aldol reaction between acetone and 5-hydroxymethylfurfural. The results indicate that the OMS-dendron materials have potential as solid base catalysts for a range of reactions.

Wang, Qingqing

2011-05-01T23:59:59.000Z

396

Maximizing Power Output in Homogeneous Charge Compression Ignition (HCCI) Engines and Enabling Effective Control of Combustion Timing  

E-Print Network (OSTI)

fuels in Diesel engines. Biodiesel, for example, is one fuelalternative fuels like biodiesel. 2.2.3 Homogeneous charge

Saxena, Samveg

2011-01-01T23:59:59.000Z

397

Molecular-scale, Three-dimensional Non-Platinum Group Metal Electrodes for Catalysis of Fuel Cell Reactions  

NLE Websites -- All DOE Office Websites (Extended Search)

Molecular-scale, Three-dimensional Non-Platinum Group Molecular-scale, Three-dimensional Non-Platinum Group Metal Electrodes for Catalysis of Fuel Cell Reactions John B. Kerr Lawrence Berkeley National Laboratory (LBNL) September 30, 2009 Team Members: Adam Weber, Rachel Segalman, Robert Kostecki, Jeff Reimer, John Arnold, Martin Head-Gordon (LBNL). Piotr Zelenay, James Boncella, Yu Seung Kim, Neil Henson, Jerzy Chlistunoff (LANL). Steve Hamrock, Radoslav Atanasoski (3M) Budget: DOE share - $9.58MM over four years; 3M share - in-kind over four years. 2 Objectives 1) Demonstrate that non-platinum group metal catalysts can be used for oxygen reduction in polymer-coated electrode structures based on polyelectrolyte membranes. 2) Incorporate catalysts into polymer binders of composite electrodes for the construction of MEAs to demonstrate that this

398

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

Science Conference Proceedings (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

399

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

SciTech Connect

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

400

CCEI | U.S. DOE Office of Science (SC)  

Office of Science (SC) Website

novel catalysts for the efficient conversion of the complex molecules comprising biomass into chemicals and fuels. Research Topics: catalysis (homogeneous), catalysis...

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

Review Article Activities of Heterogeneous Acid-Base Catalysts for Fragrances Synthesis: A Review  

E-Print Network (OSTI)

This paper reviews various types of heterogeneous acid-base catalysts for fragrances preparation. Catalytic activities of the various types of heterogeneous acid and base catalysts in fragrances preparation, i.e. nonzeolitic, zeolitic, and mesoporous molecular sieves, have been reported. Generally, heterogeneous acid catalysts are more commonly used in fragrance synthesis as compared to heterogeneous base catalysts. Heteropoly acids and hydrotalcites type catalysts are widely used as heterogeneous acid and base catalysts, respectively. © 2013 BCREC UNDIP. All rights reserved.

H. Hartati; Mardi Santoso; Sugeng Triwahyono; Didik Prasetyoko

2013-01-01T23:59:59.000Z

402

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

403

Accounting of heterogeneity in the estimation of radiation risks  

Science Conference Proceedings (OSTI)

The problem is considered of taking account of heterogeneity in the individual radiosensitivity in evaluating the radiation risk of the origin of a disease in a group of persons subjected to the radiation action. Mathematical models are described for ... Keywords: 87.15.Aa

A. I. Mikhalskii; V. K. Ivanov; S. Yu. Chekin; M. A. Maksyutov; V. V. Kashcheev

2008-06-01T23:59:59.000Z

404

Approaches to Relating and Integrating Semantic Data from Heterogeneous Sources  

Science Conference Proceedings (OSTI)

Integrating and relating heterogeneous data using inference is one of the cornerstones of semantic technologies and there are a variety of ways in which this may be achieved. Cross source relationships can be automatically translated or inferred using ... Keywords: inference, semantic integration, OWL/RDF, rules, query

John Keeney; Aidan Boran; Ivan Bedini; Christopher J. Matheus; Peter F. Patel-Schneider

2011-08-01T23:59:59.000Z

405

Object Exchange Across Heterogeneous Information Sources Yannis Papakonstantinou  

E-Print Network (OSTI)

heterogeneous bibliographic information sources. We also describe two general-purpose libraries we have consist of free-form text; even if the text does have some structure, the elds" e.g., author, title, etc information format CLIENT Query translated into Query Language of Info Source Info Source Result from Query

Papakonstantinou, Yannis

406

Object Exchange Across Heterogeneous Information Sources \\Lambda Yannis Papakonstantinou  

E-Print Network (OSTI)

and language have been used to integrate heterogeneous bibliographic information sources. We also describe two schema to describe the data. For example, a source may consist of free­form text; even if the text does information format CLIENT Query translated into Query Language of Info Source Info Source Result from Query

Papakonstantinou, Yannis

407

Unified Access to Heterogeneous Data in Cultural Heritage  

E-Print Network (OSTI)

. This approach raises the following two main questions: 1. Is a full-text IR solution suitable for unified access the combined data of a large museum. As a first step, we modified a typical full-text IR system and loaded up heterogeneous collections of the Gemeentemuseum. But how can we compare the retrieval effectiveness of a full-text

Kamps, Jaap

408

Electrostatic Interaction of Heterogeneously Charged Surfaces with Semipermeable Membranes  

E-Print Network (OSTI)

In this paper we study the electrostatic interaction of a heterogeneously charged wall with a neutral semipermeable membrane. The wall consists of periodic stripes, where the charge density varies in one direction. The membrane is in a contact with a bulk reservoir of an electrolyte solution and separated from the wall by a thin film of salt-free liquid. One type of ions (small counterions) permeates into the gap and gives rise to a distance-dependent membrane potential, which translates into a repulsive electrostatic disjoining pressure due to an overlap of counterion clouds in the gap. To quantify it we use two complementary approaches. First, we propose a mean-field theory based on a linearized Poisson-Boltzmann equation and Fourier analysis. These calculations allow us to estimate the effect of a heterogeneous charge pattern at the wall on the induced heterogeneous membrane potential, and the value of the disjoining pressure as a function of the gap. Second, we perform Langevin dynamics simulations of the same system with explicit ions. The results of the two approaches are in good agreement with each other at low surface charge and small gap, but differ due to nonlinearity at the higher charge. These results demonstrate that a heterogeneity of the wall charge can lead to a huge reduction in the electrostatic repulsion, which could dramatically facilitate a self-assembly in complex synthetic and biological systems.

Salim R. Maduar; Vladimir Lobaskin; Olga I. Vinogradova

2013-07-17T23:59:59.000Z

409

A Heuristic Algorithm for Mapping Communicating Tasks on Heterogeneous Resources  

E-Print Network (OSTI)

data-processing tasks onto heterogeneous resources (i.e., processors and links of various capacities) is presented. The algorithm tries to achieve a good throughput of the whole data-processing pipeline, taking of geographically distributed compute- and data-resources connected with diverse communication ca- pacities, forming

Taura, Kenjiro

410

A Heuristic Algorithm for Mapping Communicating Tasks on Heterogeneous Resources  

E-Print Network (OSTI)

data­processing tasks onto heterogeneous resources (i.e., processors and links of various capacities) is presented. The algorithm tries to achieve a good throughput of the whole data­processing pipeline, taking of geographically distributed compute­ and data­resources connected with diverse communication ca­ pacities, forming

Chien, Andrew A.

411

Physics-based seismic hazard analysis on petascale heterogeneous supercomputers  

Science Conference Proceedings (OSTI)

We have developed a highly scalable and efficient GPU-based finite-difference code (AWP) for earthquake simulation that implements high throughput, memory locality, communication reduction and communication/computation overlap and achieves linear scalability ... Keywords: CyberShake, GPU, SCEC, earthquake ground motions, hybrid heterogeneous, seismic hazard analysis, weak scaling

Y. Cui, E. Poyraz, K. B. Olsen, J. Zhou, K. Withers, S. Callaghan, J. Larkin, C. Guest, D. Choi, A. Chourasia, Z. Shi, S. M. Day, P. J. Maechling, T. H. Jordan

2013-11-01T23:59:59.000Z

412

Inference of tumor phylogenies from genomic assays on heterogeneous samples  

Science Conference Proceedings (OSTI)

Motivation: Tumorigenesis can in principle result from many combinations of mutations, but only a few roughly equivalent sequences of mutations, or "progression pathways", seem to account for most human tumors. There is hope that by cataloguing ... Keywords: array comparative genomic hybridization (aCGH), cancer, phylogenetics, tumor heterogeneity, tumor progression pathway, unmixing

Ayshwarya Subramanian; Stanley Shackney; Russell Schwartz

2011-08-01T23:59:59.000Z

413

Polymorphic Actor-Oriented Design for Heterogeneous Embedded Software  

E-Print Network (OSTI)

Polymorphic Actor-Oriented Design for Heterogeneous Embedded Software Center for Hybrid HPEC, Sept. 23, 2003 Boston, MA, USA #12;Chess, UC Berkeley, E. A. Lee 2 Actor-Oriented Design · Object orientation: class name data methods call return What flows through an object is sequential control · Actor

Kepner, Jeremy

414

Distributed gang scheduling in networks of heterogenous workstations  

Science Conference Proceedings (OSTI)

The wide availability of workstation networks and the rapid evolution of workstation technology is a motivation for investigating methods of harnessing the full power of such systems. Individual workstations are not usually effectively utilized by their ... Keywords: Concurrent processing, Dynamic scheduling, Heterogenous distributed systems, Migrations, Workstation networks

Khaled Al-Saqabi; Syed Sarwar; Kassem Saleh

1997-07-01T23:59:59.000Z

415

A middleware-based approach for heterogeneous wireless sensor networks  

Science Conference Proceedings (OSTI)

Wireless sensor networks (WSN) are networked embedded systems that use small size devices with some processing and short-range radio communication capabilities for monitoring and controlling systems and environments. However, languages and IDE (Integrated ... Keywords: heterogeneous networks, middleware, wireless sensor networks

F. Graziosi; L. Pomante; D. Pacifico

2008-07-01T23:59:59.000Z

416

WSN-inspired sleep protocols for heterogeneous LTE networks  

Science Conference Proceedings (OSTI)

The tremendous increase of the traffic demand in cellular networks imposes a massive densification of the traditional cellular infrastructure. The network architecture becomes heterogenous, in particular 4G networks where LTE micro eNodeBs are deployed ... Keywords: cellular network, energy optimization, switch off mechanisms, topology control

Iulia Tunaru, Hervé Rivano, Fabrice Valois

2013-11-01T23:59:59.000Z

417

Synapse: a scalable protocol for interconnecting heterogeneous overlay networks  

Science Conference Proceedings (OSTI)

This paper presents Synapse, a scalable protocol for information retrieval over the inter-connection of heterogeneous overlay networks. Applications on top of Synapse see those intra-overlay networks as a unique inter-overlay network. Scalability in ... Keywords: information retrieval, overlay networks, peer-to-peer

Luigi Liquori; Cédric Tedeschi; Laurent Vanni; Francesco Bongiovanni; Vincenzo Ciancaglini; Bojan Marinkovi?

2010-05-01T23:59:59.000Z

418

Leveraging Heterogeneity for Energy Minimization in Data Centers  

Science Conference Proceedings (OSTI)

Energy consumption in data centers is nowadays a critical objective because of its dramatic environmental and economic impact. Over the last years, several approaches have been proposed to tackle the energy/cost optimization problem, but most of them ... Keywords: heterogeneous data centers, energy-aware optimization, green computing

Marina Zapater; Jose L. Ayala; Jose M. Moya

2012-05-01T23:59:59.000Z

419

State-of-the-art in heterogeneous computing  

Science Conference Proceedings (OSTI)

Node level heterogeneous architectures have become attractive during the last decade for several reasons: compared to traditional symmetric CPUs, they offer high peak performance and are energy and/or cost efficient. With the increase of fine-grained ... Keywords: Power-efficient architectures, energy and power consumption, microprocessor performance, parallel computer architecture, stream or vector architectures

Andre R. Brodtkorb; Christopher Dyken; Trond R. Hagen; Jon M. Hjelmervik; Olaf O. Storaasli

2010-01-01T23:59:59.000Z

420

Static Worksharing Strategies for Heterogeneous Computers with Unrecoverable Failures  

E-Print Network (OSTI)

Static Worksharing Strategies for Heterogeneous Computers with Unrecoverable Failures Anne Benoit1 computers that can assist in computing the workload. How can one best utilize the computers? Two features complicate this question. First, the remote computers may differ from one another in speed. Second, each

Paris-Sud XI, Université de

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

Application Deployment over Heterogeneous Grids using Distributed Ant  

E-Print Network (OSTI)

Application Deployment over Heterogeneous Grids using Distributed Ant Wojtek Goscinski and David in a secure, distributed, environment [2]. How- ever, a significant, unaddressed, challenge for Grid computing an automated applica- tion deployment system with a user-oriented approach, Distributed Ant (DistAnt) [3

Abramson, David

422

CATALYSIS SCIENCE INITIATIVE: From First Principles Design to Realization of Bimetallic Catalysts for Enhanced Selectivity  

DOE Green Energy (OSTI)

In this project, we have integrated state-of-the-art Density Functional Theory (DFT) models of heterogeneous catalytic processes with high-throughput screening of bimetallic catalytic candidates for important industrial problems. We have studied a new class of alloys characterized by a surface composition different from the bulk composition, and investigated their stability and activity for the water-gas shift reaction and the oxygen reduction reaction. The former reaction is an essential part of hydrogen production; the latter is the rate-limiting step in low temperature H2 fuel cells. We have identified alloys that have remarkable stability and activity, while having a much lower material cost for both of these reactions. Using this knowledge of bimetallic interactions, we have also made progress in the industrially relevant areas of carbohydrate reforming and conversion of biomass to liquid alkanes. One aspect of this work is the conversion of glycerol (a byproduct of biodiesel production) to synthesis gas. We have developed a bifunctional supported Pt catalyst that can cleave the carbon-carbon bond while also performing the water-gas shift reaction, which allows us to better control the H2:CO ratio. Knowledge gained from the theoretical metal-metal interactions was used to develop bimetallic catalysts that perform this reaction at low temperature, allowing for an efficient coupling of this endothermic reaction with other reactions, such as Fischer-Tropsch or methanol synthesis. In our work on liquid alkane production from biomass, we have studied deactivation and selectivity in these areas as a function of metal-support interactions and reaction conditions, with an emphasis on the bifunctionality of the catalysts studied. We have identified a stable, active catalyst for this process, where the selectivity and yield can be controlled by the reaction conditions. While complete rational design of catalysts is still elusive, this work demonstrates the power of combining the insights gained from theoretical models and the work of experiments to develop new catalysts for current and future industrial challenges.

MAVRIKAKIS, MANOS

2007-05-03T23:59:59.000Z

423

Grounding Analysis in Heterogeneous Soil Models: Application to Underground Substations  

Science Conference Proceedings (OSTI)

Most of the research and development work done until now in earthing analysis is devoted to cases where the soil can be modelled in terms of an homogeneous and isotropic semi-infinite continuous medium, being the soil resistivity an order of magnitude ... Keywords: grounding analysis, earthing analysis, underground substations

Ignasi Colominas; Jose Paris; Xesus Nogueira; Fermin Navarrina; Manuel Casteleiro

2012-05-01T23:59:59.000Z

424

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, hydrosilation, olefin oxidation, isomerization, hydrocyanation, olefin metathesis, olefin polymerization, carbonylation, enantioselective catalysis and photoduplication. These catalysts are easily separated from the products, and can be reused repeatedly, making these systems very economical.

Angelici, Robert J. (Ames, IA); Gao, Hanrong (Ames, IA)

1998-08-04T23:59:59.000Z

425

Characterization of oil and gas reservoir heterogeneity. Final report  

SciTech Connect

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

Homogenization of a spectral equation with drift in linear Guillaume Bal  

E-Print Network (OSTI)

theory posed in a periodic heterogeneous domain. This equation models the stability of nuclear reactor Introduction The power distribution in a nuclear reactor is determined by solving a linear transport spectral in radiative transfer theory, which models the propagation of acoustic, electromagnetic, or elastic waves

Bal, Guillaume

427

Quantized states in homogenous polarized GaInN GaN quantum wells  

E-Print Network (OSTI)

Quantized states in homogenous polarized GaInN GaN quantum wells C. Wetzel1, S. Kamiyama1, H. Amano wells is calculated in a single particle model. The act- ing electric eld in the wells and the band gap-dimensional well layers our approach is based on induction from results obtained at the binary GaN barri- ers

Wetzel, Christian M.

428

Network reconfiguration of distributed controlled homogenous power inverter network using composite Lyapunov function based reachability bound  

Science Conference Proceedings (OSTI)

We outline a methodology to determine the reachability bound of a homogeneous interactive power network (IPN) with wireless distributed control by using a piecewise linear (PWL) model of the system. By formulating a convex optimization problem based ... Keywords: Lyapunov stability, Markov-chain model, linear matrix inequality, piecewise linear systems, reaching conditions, switching power converters

Sudip K. Mazumder; Kaustuva Acharya; Muhammad Tahir

2007-07-01T23:59:59.000Z

429

Spatial homogenization of thermal feedback regions in Monte Carlo reactor calculations  

SciTech Connect

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

430

Fundamental solutions for a class of non-elliptic homogeneous differential operators  

E-Print Network (OSTI)

We compute temperate fundamental solutions of homogeneous differential operators with real-principal type symbols. Via analytic continuation of meromorphic distributions, fundamental solutions for these non-elliptic operators can be constructed in terms of radial averages and invariant distributions on the unit sphere.

Brice Camus

2007-04-05T23:59:59.000Z

431

The queue protocol: a deadlock-free, homogeneous, non-two-phase locking protocol  

Science Conference Proceedings (OSTI)

The M-pitfall protocol (MPP) is the most general homogeneous non-two-phase locking protocol which supports shared and exclusive locks. It has two major disadvantages: it is not deadlock-free and it has the paradoxical property that concurrency is often ...

Udo Kelter

1988-03-01T23:59:59.000Z

432

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

433

Scenario Formulation of Stochastic Linear Programs and the Homogeneous Self-Dual Interior-Point Method  

Science Conference Proceedings (OSTI)

We consider a homogeneous self-dual interior-point algorithm for solving multistage stochastic linear programs. The algorithm is particularly suitable for the so-called “scenario formulation” of the problem, whose constraint system consists ... Keywords: decomposition, interior-point methods, multistage stochastic linear programs

Jie Sun; Xinwei Liu

2006-01-01T23:59:59.000Z

434

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

DOE Green Energy (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

435

PARALLEL COMPUTING AIDED DESIGN OF EARTHING SYSTEMS FOR ELECTRICAL SUBSTATIONS IN NON HOMOGENEOUS SOIL  

E-Print Network (OSTI)

and design of grounding systems of electrical substations have been proposed, most of them based on practicePARALLEL COMPUTING AIDED DESIGN OF EARTHING SYSTEMS FOR ELECTRICAL SUBSTATIONS IN NON HOMOGENEOUS Abstract. An accurate design of grounding systems is essential to assure the safety of the persons

Colominas, Ignasi

436

The homogeneity theorem for supergravity backgrounds II: the six-dimensional theories  

E-Print Network (OSTI)

We prove that supersymmetry backgrounds of (1,0) and (2,0) six-dimensional supergravity theories preserving more than one half of the supersymmetry are locally homogeneous. As a byproduct we also establish that the Killing spinors of such a background generate a Lie superalgebra.

Figueroa-O'Farrill, José

2013-01-01T23:59:59.000Z

437

The Three-Dimensional Steady Circulation in a Homogenous Ocean Induced by a Stationary Hurricane  

Science Conference Proceedings (OSTI)

Based on the classical Ekman layer theory, a simple analytical solution of the steady flow induced by a stationary hurricane in a homogenous ocean is discussed. The model consists of flow converging in an inward spiral in the deeper layer and ...

Zhu Min Lu; Rui Xin Huang

2010-07-01T23:59:59.000Z

438

An efficient parallel simulation of interacting inertial particles in homogeneous isotropic turbulence  

Science Conference Proceedings (OSTI)

This study has conducted parallel simulations of interacting inertial particles in statistically-steady isotropic turbulence using a newly-developed efficient parallel simulation code. Flow is computed with a fourth-order finite-difference method and ... Keywords: Homogeneous isotropic turbulence, Hydrodynamic interaction, Parallel computing, Particle collision

Ryo Onishi, Keiko Takahashi, J. C. Vassilicos

2013-06-01T23:59:59.000Z

439

A Scaling Theory for Horizontally Homogeneous, Baroclinically Unstable Flow on a Beta Plane  

Science Conference Proceedings (OSTI)

The scaling argument developed by the authors in a previous work for eddy amplitudes and fluxes in a horizontally homogeneous, two-layer model on an f plane is extended to a ? plane. In terms of the nondimensional number ?=U/(??2), where ? is the ...

Isaac M. Held; Vitaly D. Larichev

1996-04-01T23:59:59.000Z

440

On the nonexistence of a Lobachevsky geometry model of an isotropic and homogeneous universe  

Science Conference Proceedings (OSTI)

According to the Einstein cosmological principle, our universe is homogeneous and isotropic, i.e. its curvature is constant at any point and in any direction. On large scales, when all local irregularities are ignored, this assumption has been confirmed ... Keywords: Gauss-Kronecker curvature, Lobachevsky and Riemannian geometry, geometric cosmology, manifolds, modelling, umbilic points

Michal K?ížek; Jana Pradlová

2003-01-01T23:59:59.000Z

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.


441

Dosimetric verification of the anisotropic analytical algorithm in lung equivalent heterogeneities with and without bone equivalent heterogeneities  

SciTech Connect

Purpose: In this study, the authors evaluated the accuracy of dose calculations performed by the convolution/superposition based anisotropic analytical algorithm (AAA) in lung equivalent heterogeneities with and without bone equivalent heterogeneities. Methods: Calculations of PDDs using the AAA and Monte Carlo simulations (MCNP4C) were compared to ionization chamber measurements with a heterogeneous phantom consisting of lung equivalent and bone equivalent materials. Both 6 and 10 MV photon beams of 4x4 and 10x10 cm{sup 2} field sizes were used for the simulations. Furthermore, changes of energy spectrum with depth for the heterogeneous phantom using MCNP were calculated. Results: The ionization chamber measurements and MCNP calculations in a lung equivalent phantom were in good agreement, having an average deviation of only 0.64{+-}0.45%. For both 6 and 10 MV beams, the average deviation was less than 2% for the 4x4 and 10x10 cm{sup 2} fields in the water-lung equivalent phantom and the 4x4 cm{sup 2} field in the water-lung-bone equivalent phantom. Maximum deviations for the 10x10 cm{sup 2} field in the lung equivalent phantom before and after the bone slab were 5.0% and 4.1%, respectively. The Monte Carlo simulation demonstrated an increase of the low-energy photon component in these regions, more for the 10x10 cm{sup 2} field compared to the 4x4 cm{sup 2} field. Conclusions: The low-energy photon by Monte Carlo simulation component increases sharply in larger fields when there is a significant presence of bone equivalent heterogeneities. This leads to great changes in the build-up and build-down at the interfaces of different density materials. The AAA calculation modeling of the effect is not deemed to be sufficiently accurate.

Ono, Kaoru; Endo, Satoru; Tanaka, Kenichi; Hoshi, Masaharu; Hirokawa, Yutaka [Department of Radiation Physics, Hiroshima Heiwa Clinic, 1-31 Kawaramachi, Naka-ku, Hiroshima 730-0856 (Japan); Quantum Energy Applications, Graduate School of Engineering, Hiroshima University, 4-1 Kagamiyama, Higashi-Hiroshima 730-8527 (Japan); Center of Medical Education, Sapporo Medical University, 17 Minami 1 Jo, Chuo-ku, Sapporo 060-8556 (Japan); Research Institute for Radiation Biology and Medicine, Hiroshima University, 1-2-3 Kasumi, Minami-ku, Hiroshima 734-8553 (Japan); Department of Radiation Oncology, Hiroshima Heiwa Clinic, 1-31 Kawaramachi, Naka-ku, Hiroshima 730-0856 (Japan)

2010-08-15T23:59:59.000Z

442

An aspartate and a water molecule mediate efficient acid-base catalysis in a tailored antibody pocket  

DOE Green Energy (OSTI)

Design of catalysts featuring multiple functional groups is a desirable, yet formidable goal. Antibody 13G5, which accelerates the cleavage of unactivated benzisoxazoles, is one of few artificial enzymes that harness an acid and a base to achieve efficient proton transfer. X-ray structures of the Fab-hapten complexes of wild-type 13G5 and active-site variants now afford detailed insights into its mechanism. The parent antibody preorganizes Asp{sup H35} and Glu{sup L34} to abstract a proton from substrate and to orient a water molecule for leaving group stabilization, respectively. Remodeling the environment of the hydrogen bond donor with a compensatory network of ordered waters, as seen in the Glu{sup L34} to alanine mutant, leads to an impressive 10{sup 9}-fold rate acceleration over the nonenzymatic reaction with acetate, illustrating the utility of buried water molecules in bifunctional catalysis. Generalization of these design principles may aid in creation of catalysts for other important chemical transformations.

Debler, Erik W.; Müller, Roger; Hilvert, Donald; Wilson, Ian A.; (Scripps); (ETH Zurich)

2009-12-01T23:59:59.000Z

443

Medical Knowledge Morphing: Towards Case-Specific Integration of Heterogeneous Medical Knowledge Resources  

E-Print Network (OSTI)

Medical Knowledge Morphing: Towards Case-Specific Integration of Heterogeneous Medical Knowledge interplay between various medical knowledge modalities--the spectrum of medical knowledge modalities morphing--a knowledge modeling task that allows the integration of heterogeneous medical knowledge

Abidi, Syed Sibte Raza

444

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

445

Contention awareness and fault-tolerant scheduling for precedence constrained tasks in heterogeneous systems  

Science Conference Proceedings (OSTI)

Heterogeneous distributed systems are widely deployed for executing computationally intensive parallel applications with diverse computing needs. Such environments require effective scheduling strategies that take into account both algorithmic and architectural ... Keywords: Communication contention, Fault-tolerant scheduling, Heterogeneous systems

Anne Benoit; Mourad Hakem; Yves Robert

2009-02-01T23:59:59.000Z

446

NERC | U.S. DOE Office of Science (SC)  

NLE Websites -- All DOE Office Websites (Extended Search)

NERC NERC Energy Frontier Research Centers (EFRCs) EFRCs Home Centers Research Science Highlights News & Events Publications Contact BES Home Centers NERC Print Text Size: A A A RSS Feeds FeedbackShare Page Non-equilibrium Energy Research Center (NERC) Director(s): Bartosz A. Grzybowski Lead Institution: Northwestern University Mission: To understand self-organization in dissipative, far-from-equilibrium systems and to use this knowledge to synthesize adaptive, reconfigurable materials for energy storage and transduction. Research Topics: catalysis (homogeneous), catalysis (heterogeneous), thermal conductivity, thermoelectric, bio-inspired, energy storage (including batteries and capacitors), superconductivity, mechanical behavior, charge transport, materials and chemistry by design, synthesis (novel materials), synthesis

447

emc2 | U.S. DOE Office of Science (SC)  

Office of Science (SC) Website

emc2 emc2 Energy Frontier Research Centers (EFRCs) EFRCs Home Centers Research Science Highlights News & Events Publications Contact BES Home Centers emc2 Print Text Size: A A A RSS Feeds FeedbackShare Page Energy Materials Center at Cornell (EMC2) Director(s): Hector D. Abruna Lead Institution: Cornell University Mission: To advance the science of energy conversion and storage by understanding and exploiting fundamental properties of active materials and their interfaces. Research Topics: catalysis (homogeneous), catalysis (heterogeneous), energy storage (including batteries and capacitors), hydrogen and fuel cells, defects, charge transport, membrane, materials and chemistry by design, synthesis (novel materials), synthesis (self-assembly), synthesis (scalable

448

CABS | U.S. DOE Office of Science (SC)  

NLE Websites -- All DOE Office Websites (Extended Search)

CABS CABS Energy Frontier Research Centers (EFRCs) EFRCs Home Centers Research Science Highlights News & Events Publications Contact BES Home Centers CABS Print Text Size: A A A RSS Feeds FeedbackShare Page Center for Advanced Biofuel Systems (CABS) Director(s): Jan Jaworski Lead Institution: Donald Danforth Plant Science Center Mission: To generate the fundamental knowledge required to increase the efficiency of photosynthesis and production of energy-rich molecules in plants. Research Topics: catalysis (homogeneous), catalysis (heterogeneous), solar (fuels), photosynthesis (natural and artificial), biofuels (including algae and biomass), bio-inspired, charge transport, carbon capture, synthesis (novel materials) Materials Studied: MATERIALS: biological (DNA, protein)

449

CCHF | U.S. DOE Office of Science (SC)  

Office of Science (SC) Website

CCHF CCHF Energy Frontier Research Centers (EFRCs) EFRCs Home Centers Research Science Highlights News & Events Publications Contact BES Home Centers CCHF Print Text Size: A A A RSS Feeds FeedbackShare Page Center for Catalytic Hydrocarbon Functionalization (CCHF) Director(s): T. Brent Gunnoe Lead Institution: University of Virginia Mission: To develop, validate, and optimize new methods to rearrange the bonds of hydrocarbons, implement enzymatic strategies into synthetic systems, and design optimal environments for catalysts that can be used to reversibly functionalize hydrocarbons, especially for more efficient use of natural gas including low temperature conversion to liquid fuels. Research Topics: catalysis (homogeneous), catalysis (heterogeneous), bio-inspired, hydrogen

450

CME | U.S. DOE Office of Science (SC)  

Office of Science (SC) Website

CME CME Energy Frontier Research Centers (EFRCs) EFRCs Home Centers Research Science Highlights News & Events Publications Contact BES Home Centers CME Print Text Size: A A A RSS Feeds FeedbackShare Page Center for Molecular Electrocatalysis Director(s): R. Morris Bullock Lead Institution: Pacific Northwest National Laboratory Mission: To understand, design and develop molecular electrocatalysts for solar fuel production and use. Research Topics: catalysis (homogeneous), catalysis (heterogeneous), solar (fuels), bio-inspired, energy storage (including batteries and capacitors), hydrogen and fuel cells, charge transport, materials and chemistry by design, synthesis (novel materials) Materials Studied: MATERIALS: metal Experimental and Theoretical Methods: X-ray diffraction and scattering, density functional theory (DFT), quantum

451

ANSER | U.S. DOE Office of Science (SC)  

NLE Websites -- All DOE Office Websites (Extended Search)

ANSER ANSER Energy Frontier Research Centers (EFRCs) EFRCs Home Centers Research Science Highlights News & Events Publications Contact BES Home Centers ANSER Print Text Size: A A A RSS Feeds FeedbackShare Page Argonne-Northwestern Solar Energy Research (ANSER) Center Director(s): Michael R. Wasielewski Lead Institution: Northwestern University Mission: To revolutionize our understanding of molecules, materials and methods necessary to create dramatically more efficient technologies for solar fuels and electricity production. Research Topics: catalysis (homogeneous), catalysis (heterogeneous), solar (photovoltaic), solar (fuels), photosynthesis (natural and artificial), bio-inspired, hydrogen and fuel cells, electrodes - solar, defects, charge transport, spin dynamics, membrane, materials and chemistry by design, optics,

452

AP Members  

NLE Websites -- All DOE Office Websites (Extended Search)

Group Members Group Members Principal Investigators Etsuko Fujita (Lead PI) Photochemical carbon dioxide reduction using transition-metal complexes; electrocatalysis of hydrogen and carbon dioxide reduction with non-noble metal based catalysts; water oxidation catalysis; kinetics and mechanism of photochemical and redox reactions Javier Concepcion (PI) David Grills (PI) Application of transient infrared spectroscopy to kinetics and catalysis; characterization of reaction intermediates, CO2 reduction in supercritical CO2 Jim Muckerman (PI) Application of theory and computation to photocatalysis and electrocatalysis; mechanistic studies of hydrogen production, carbon dioxide reduction and water oxidation in both homogeneous and heterogeneous systems Dmitry Polyansky (PI)

453

Defining and controlling the heterogeneity of a cluster: The Wrekavoc tool  

Science Conference Proceedings (OSTI)

The experimental validation and the testing of solutions that are designed for heterogeneous environments are challenging. We introduce Wrekavoc as an accurate tool for this purpose: it runs unmodified applications on emulated multi-site heterogeneous ... Keywords: Emulation, Heterogeneous systems, Performance modeling, Tool for experimentation

Louis-Claude Canon; Olivier Dubuisson; Jens Gustedt; Emmanuel Jeannot

2010-05-01T23:59:59.000Z

454

A behaviour-based control architecture for heterogeneous modular, multi-configurable, chained micro-robots  

Science Conference Proceedings (OSTI)

This article presents a new control architecture designed for heterogeneous modular, multi-configurable, chained micro-robots. This architecture attempts to fill the gap that exists in heterogeneous modular robotics research, in which little work has ... Keywords: Architecture, Behaviour-based, Control, Heterogeneous, Modular, Multi-configurable

A. Brunete; M. Hernando; E. Gambao; J. E. Torres

2012-12-01T23:59:59.000Z

455

A novel terminal-controlled handover scheme in heterogeneous wireless networks  

Science Conference Proceedings (OSTI)

In the next generation heterogeneous wireless networks, a mobile terminal (MT) with a multi-interface may have network access from different service providers using various technologies. In spite of this heterogeneity, seamless intersystem mobility is ... Keywords: Fuzzy logic, Handover, Heterogeneous networks

Xu Haibo; Tian Hui; Zhang Ping

2010-03-01T23:59:59.000Z

456

Research Note: A high performance algorithm for static task scheduling in heterogeneous distributed computing systems  

Science Conference Proceedings (OSTI)

Effective task scheduling is essential for obtaining high performance in heterogeneous distributed computing systems (HeDCSs). However, finding an effective task schedule in HeDCSs requires the consideration of both the heterogeneity of processors and ... Keywords: Directed acyclic graph, Heterogeneous systems, Heuristics, Parallel processing, Task scheduling

Mohammad I. Daoud; Nawwaf Kharma

2008-04-01T23:59:59.000Z

457

A hybrid heuristic-genetic algorithm for task scheduling in heterogeneous processor networks  

Science Conference Proceedings (OSTI)

Efficient task scheduling on heterogeneous distributed computing systems (HeDCSs) requires the consideration of the heterogeneity of processors and the inter-processor communication. This paper presents a two-phase algorithm, called H2GS, for task scheduling ... Keywords: Directed acyclic graph, Genetic algorithms, Heterogeneous systems, List-based scheduling heuristics, Parallel and distributed processing, Task scheduling

Mohammad I. Daoud; Nawwaf Kharma

2011-11-01T23:59:59.000Z

458

Mining Large Heterogeneous Graphs using Cray s Urika  

SciTech Connect

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

459

A heterogeneous graphics procedure for visualization of massively parallel solutions  

SciTech Connect

Scientific visualization is playing an increasingly important role in the analysis and interpretation of massively parallel CFD simulations due to the enormous volume of data that can be generated on these machines. In this paper we will describe the development of a visualization technique based on a parallel analogue to the Marching Cubes algorithm. The algorithm has been developed for Multiple-Instruction, Multiple-Data (MIMD) massively parallel computers and is designed to take advantage of the heterogeneous programming capabilities of the MIMD architecture. We examine several different configurations and conclude that for producing animations the best one, in terms of both frame generation time and disk usage, is to run the two applications heterogeneously and send the resulting geometry description directly to a workstation for rendering, thereby totally eliminating the use of files from the animation process.

1993-01-01T23:59:59.000Z

460

A heterogeneous graphics procedure for visualization of massively parallel solutions  

SciTech Connect

Scientific visualization is playing an increasingly important role in the analysis and interpretation of massively parallel CFD simulations due to the enormous volume of data that can be generated on these machines. In this paper we will describe the development of a visualization technique based on a parallel analogue to the Marching Cubes algorithm. The algorithm has been developed for Multiple-Instruction, Multiple-Data (MIMD) massively parallel computers and is designed to take advantage of the heterogeneous programming capabilities of the MIMD architecture. We examine several different configurations and conclude that for producing animations the best one, in terms of both frame generation time and disk usage, is to run the two applications heterogeneously and send the resulting geometry description directly to a workstation for rendering, thereby totally eliminating the use of files from the animation process.

1993-03-01T23:59:59.000Z

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.


461

Correlating Spatial Heterogeneities in Porosity and Permeability with Metal  

NLE Websites -- All DOE Office Websites (Extended Search)

Correlating Spatial Heterogeneities in Porosity and Permeability with Metal Correlating Spatial Heterogeneities in Porosity and Permeability with Metal Poisoning within an Individual Catalyst Particle using X-ray Microscopy Wednesday, August 21, 2013 - 1:30pm SLAC, Conference Room 137-226 Presented by Darius Morris, Stanford Synchrotron Radiation Lightsource Fluid catalytic cracking (FCC) is a refining process for converting large and/or heavy molecules of oil feedstock into smaller and lighter hydrocarbons such as gasoline. During the cracking process, metal contaminants from the oil feedstock deactivate and restrict access into the catalyst particle, thus reducing the yield of gasoline byproducts. Full-field transmission X-ray microscopy (TXM) has been used to determine the 3D composition and structure of an equilibrated (spent) FCC particle in

462

Learning with Heterogeneous Expectations in an Evolutionary World  

E-Print Network (OSTI)

65, 1059-1095. [6] De Grauwe, P.,Dewachter, H.,Embrechts, M. (1993) Exchange Rate Theory: Chaotic Models of Foreign Exchange Markets. Blackwell Publishers, Oxford, UK. [7] Evans, G., Honkapohja, S. (1997) ?Least Squares Learning with Heterogenous... Expectations?, Economic Letters 52, 197-201. [8] Evans, G., Honkapohja, S. (2001) Learning and Expectations in Macroeconomics, Princeton University Press, Princeton, NJ. [9] Evans, G., Honkapohja, S.,Marimon, R. (2001) ?Convergence in Monetary In?ation Models...

Guse, Eran A

2006-03-14T23:59:59.000Z

463

Modification of heterogeneous chemistry by complex substrate morphology  

Science Conference Proceedings (OSTI)

This is the final report of a one-year, Laboratory Directed Research and Development (LDRD) project at Los Alamos National Laboratory (LANL). Chemistry in many environmental systems is determined at some stage by heterogeneous reaction with a surface. Typically the surface exists as a dispersion or matrix of particulate matter or pores, and a determination of the heterogeneous chemistry of the system must address the extent to which the complexity of the environmental surface affects the reaction rates. Reactions that are of current interest are the series of chlorine nitrate reactions important in polar ozone depletion. The authors have applied surface spectroscopic techniques developed at LANL to address the chemistry of chlorine nitrate reactions on porous nitric and sulfuric acid ice surfaces as a model study of the measurement of complex, heterogeneous reaction rates. The result of the study is an experimental determination of the surface coverage of one adsorbed reagent and a mechanism of reactivity based on the dependence of this coverage on temperature and vapor pressure. The resulting mechanism allows the first comprehensive modeling of chlorine nitrate reaction probability data from several laboratories.

Henson, B.F.; Buelow, S.J.; Robinson, J.M.

1998-12-31T23:59:59.000Z

464

Heterogeneous composite bodies with isolated lenticular shaped cermet regions  

SciTech Connect

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

465

An approach for modeling the valve train system to control the homogeneous combustion in a compression ignition engine  

Science Conference Proceedings (OSTI)

This paper presents an approach for modeling the valve train system to obtain a homogeneous charge compression ignition (HCCI) engine from a gasoline engine. The HCCI engines use different indirect strategies to control the start of the combustion. The ... Keywords: exhaust gas recirculation, homogeneous charge compression ignition, variable valve timing

Radu Cosgarea; Corneliu Cofaru; Mihai Aleonte; Maria Luminita Scutaru; Liviu Jelenschi; Gabriel Sandu

2011-04-01T23:59:59.000Z

466

Core Designs and Economic Analyses of Homogeneous Thoria-Urania Fuel in Light Water Reactors  

SciTech Connect

The objective is to develop equilibrium fuel cycle designs for a typical pressurized water reactor (PWR) loaded with homogeneously mixed uranium-thorium dioxide (ThO{sub 2}-UO{sub 2}) fuel and compare those designs with more conventional UO{sub 2} designs.The fuel cycle analyses indicate that ThO{sub 2}-UO{sub 2} fuel cycles are technically feasible in modern PWRs. Both power peaking and soluble boron concentrations tend to be lower than in conventional UO{sub 2} fuel cycles, and the burnable poison requirements are less.However, the additional costs associated with the use of homogeneous ThO{sub 2}-UO{sub 2} fuel in a PWR are significant, and extrapolation of the results gives no indication that further increases in burnup will make thoria-urania fuel economically competitive with the current UO{sub 2} fuel used in light water reactors.

Saglam, Mehmet; Sapyta, Joe J.; Spetz, Stewart W.; Hassler, Lawrence A. [Framatome ANP, Inc. (France)

2004-07-15T23:59:59.000Z

467

Method for preparing homogeneous single crystal ternary III-V alloys  

DOE Patents (OSTI)

A method for producing homogenous single crystal III--V ternary alloys of high crystal perfection using a floating crucible system in which the outer crucible holds a ternary alloy of the composition desired to be produced in the crystal and an inner floating crucible having a narrow, melt-passing channel in its bottom wall holds a small quantity of melt of a pseudo-binary liquidus composition which would freeze into the desired crystal composition. The alloy of the floating crucible is maintained at a predetermined lower temperature than the alloy of the outer crucible, and a single crystal of the desired homogeneous alloy is pulled out of the floating crucible melt, as melt from the outer crucible flows into a bottom channel of the floating crucible at a rate that corresponds to the rate of growth of the crystal.

Ciszek, T.F.

1990-08-14T23:59:59.000Z

468

Mathematical treatment of the homogeneous Boltzmann equation for Maxwellian molecules in the presence of singular kernels  

E-Print Network (OSTI)

This paper proves the existence of weak solutions to the spatially homogeneous Boltzmann equation for Maxwellian molecules, when the initial data are chosen from the space of all Borel probability measures on R^3 with finite second moments and the (angular) collision kernel satisfies a very weak cutoff condition. Conservation of momentum and energy is also proved for these weak solutions, without resorting to any boundedness of the entropy.

Emanuele Dolera

2013-06-21T23:59:59.000Z

469

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

2011-11-03T23:59:59.000Z

470

K-groups of the quantum homogeneous space $SU_{q}(n)/SU_{q}(n-2)$  

E-Print Network (OSTI)

Quantum Steiffel manifolds were introduced by Vainerman and Podkolzin in \\cite{VP}. They classified the irreducible representations of their underlying $C^*$-algebras. Here we compute the K groups of the quantum homogeneous spaces $SU_{q}(n)/SU_{q}(n-2), n\\ge 3$. Specializing to the case $n=3$ we show that the fundamental unitary for quantum $SU(3)$ is nontrivial and is a unimodular element in $K_1$.

Chakraborty, Partha Sarathi

2010-01-01T23:59:59.000Z

471

K-groups of the quantum homogeneous space $SU_{q}(n)/SU_{q}(n-2)$.  

E-Print Network (OSTI)

Quantum Steiffel manifolds were introduced by Vainerman and Podkolzin in \\cite{VP}. They classified the irreducible representations of their underlying $C^*$-algebras. Here we compute the K groups of the quantum homogeneous spaces $SU_{q}(n)/SU_{q}(n-2), n\\ge 3$. Specializing to the case $n=3$ we show that the fundamental unitary for quantum $SU(3)$ is nontrivial and is a unimodular element in $K_1$.

Partha Sarathi Chakraborty; S. Sundar

472

Extremal Horizons with Reduced Symmetry: Hyperscaling Violation, Stripes, and a Classification for the Homogeneous Case  

E-Print Network (OSTI)

Classifying the zero-temperature ground states of quantum field theories with finite charge density is a very interesting problem. Via holography, this problem is mapped to the classification of extremal charged black brane geometries with anti-de Sitter asymptotics. In a recent paper [1], we proposed a Bianchi classification of the extremal near-horizon geometries in five dimensions, in the case where they are homogeneous but, in general, anisotropic. Here, we extend our study in two directions: we show that Bianchi attractors can lead to new phases, and generalize the classification of homogeneous phases in a way suggested by holography. In the first direction, we show that hyperscaling violation can naturally be incorporated into the Bianchi horizons. We also find analytical examples of "striped" horizons. In the second direction, we propose a more complete classification of homogeneous horizon geometries where the natural mathematics involves real four-algebras with three dimensional sub-algebras. This gives rise to a richer set of possible near-horizon geometries, where the holographic radial direction is non-trivially intertwined with field theory spatial coordinates. We find examples of several of the new types in systems consisting of reasonably simple matter sectors coupled to gravity, while arguing that others are forbidden by the Null Energy Condition. Extremal horizons in four dimensions governed by three-algebras or four-algebras are also discussed.

Norihiro Iizuka; Shamit Kachru; Nilay Kundu; Prithvi Narayan; Nilanjan Sircar; Sandip P. Trivedi; Huajia Wang

2012-12-10T23:59:59.000Z

473

Binary homogeneous nucleation: Temperature and relative humidity fluctuations and non-linearity  

SciTech Connect

This report discusses binary homogeneous nucleation involving H[sub 2]SO[sub 4] and water vapor is thought to be the primary mechanism for new particle formation in the marine boundary layer. Temperature, relative humidity, and partial pressure of H[sub 2]SO[sub 4] vapor are the most important parameters in fixing the binary homogeneous nucleation rate in the H[sub 2]SO[sub 4]/H[sub 2]O system. The combination of thermodynamic calculations and laboratory experiments indicates that this rate varies roughly as the tenth power of the saturation ratio of H[sub 2]SO[sub 4] vapor. Furthermore, the vapor pressure of H[sub 2]SO[sub 4] is a function of temperature, and similar dependencies of the binary homogeneous nucleation rate on relative humidity can be noted as well. These factors thus introduce strong non-linearities into the system, and fluctuations of temperature, relative humidity, and H[sub 2]SO[sub 4] vapor concentrations about mean values may strongly influence the nucleation rate measured in the atmosphere.

Easter, R.C. (Pacific Northwest Lab., Richland, WA (United States)); Peters, L.K. (Kentucky Univ., Lexington, KY (United States). Dept. of Chemical Engineering)

1993-01-01T23:59:59.000Z

474

Binary homogeneous nucleation: Temperature and relative humidity fluctuations and non-linearity  

SciTech Connect

This report discusses binary homogeneous nucleation involving H{sub 2}SO{sub 4} and water vapor is thought to be the primary mechanism for new particle formation in the marine boundary layer. Temperature, relative humidity, and partial pressure of H{sub 2}SO{sub 4} vapor are the most important parameters in fixing the binary homogeneous nucleation rate in the H{sub 2}SO{sub 4}/H{sub 2}O system. The combination of thermodynamic calculations and laboratory experiments indicates that this rate varies roughly as the tenth power of the saturation ratio of H{sub 2}SO{sub 4} vapor. Furthermore, the vapor pressure of H{sub 2}SO{sub 4} is a function of temperature, and similar dependencies of the binary homogeneous nucleation rate on relative humidity can be noted as well. These factors thus introduce strong non-linearities into the system, and fluctuations of temperature, relative humidity, and H{sub 2}SO{sub 4} vapor concentrations about mean values may strongly influence the nucleation rate measured in the atmosphere.

Easter, R.C. [Pacific Northwest Lab., Richland, WA (United States); Peters, L.K. [Kentucky Univ., Lexington, KY (United States). Dept. of Chemical Engineering

1993-01-01T23:59:59.000Z

475

Consumption Externalities: A Representative Consumer Model when Agents are Heterogeneous *  

E-Print Network (OSTI)

Abstract: We examine a growth model with consumption externalities where agents differ in their initial capital endowment and their reference group. We show under which conditions the aggregate equilibrium with heterogeneous agents replicates that obtained with a representative consumer, despite the fact that different individuals have different consumption levels. Next we consider the implications of the presence of consumption externalities for the long-run distributions of income and wealth. We find that, in a growing economy, “keeping up with the Joneses ” results in less inequality than would prevail in an economy with no consumption externalities.

Cecilia García-peñalosa; Stephen J. Turnovsky

2007-01-01T23:59:59.000Z

476

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

SciTech Connect

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.

2013-01-01T23:59:59.000Z

477

OH-initiated heterogeneous aging of highly oxidized organic aerosol  

Science Conference Proceedings (OSTI)

The oxidative evolution (“aging”) of organic species in the atmosphere is thought to have a major influence on the composition and properties of organic particulate matter, but remains poorly understood, particularly for the most oxidized fraction of the aerosol. Here we measure the kinetics and products of the heterogeneous oxidation of highly oxidized organic aerosol, with an aim of better constraining such atmospheric aging processes. Submicron particles composed of model oxidized organics—1,2,3,4-butanetetracarboxylic acid (C{sub 8}H{sub 10}O{sub 8}), citric acid (C{sub 6}H{sub 8}O{sub 7}), tartaric acid (C{sub 4}H{sub 6}O{sub 6}), and Suwannee River fulvic acid—were oxidized by gas-phase OH in a flow reactor, and the masses and elemental composition of the particles were monitored as a function of OH exposure. In contrast to our previous studies of less-oxidized model systems (squalane, erythritol, and levoglucosan), particle mass did not decrease significantly with heterogeneous oxidation. Carbon content of the aerosol always decreased somewhat, but this mass loss was approximately balanced by an increase in oxygen content. The estimated reactive uptake coefficients of the reactions range from 0.37 to 0.51 and indicate that such transformations occur at rates corresponding to 1-2 weeks in the atmosphere, suggesting their importance in the atmospheric lifecycle of organic particulate matter.

Kessler, Sean H.; Na