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1

HETEROGENEOUS CATALYSIS RESEARCH MEETING  

E-Print Network (OSTI)

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

Authors, Various

2011-01-01T23:59:59.000Z

2

Molecular ingredients of heterogeneous catalysis  

SciTech Connect

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

3

Homogeneous and Interfacial Catalysis in 3D Controlled Environment...  

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

Homogeneous and Interfacial Catalysis in 3D Controlled Environment FWPProject Description: Project Leader(s): Marek Pruski Principal Investigators: Andreja Bakac, Marek Pruski,...

4

Ab initio calculations in heterogeneous and homogeneous catalysis: I. Methanol to gasoline with ZSM-5. II. Carbonyl ligand effects on metal-metal bonds  

SciTech Connect

This thesis is composed of two studies in catalysis. The first is an exploration, using computational techniques, of the mechanism for the first carbon-carbon bond formation in the methanol to gasoline (MTG) reaction. The second is a study of the factors important to the understanding of ligand effects on metal-metal bonds, and in particular, to metal clusters. Three possibilities were considered as ways to activate a carbon in the MTG process prior to formation of C2 or higher hydrocarbons. These were a free radical mechanism, a surface ylide mechanism, and a possible defect site which might lead to steric crowding of CH[sub 2] groups. Although the free radical mechanism was found to be thermodynamically within the parameters of the MTG process, it contained a high transition state. Consideration of the molecules available prior to hydrocarbon build-up and their specific electronic structure, led to the view that the available carbon atoms (methanol, dimethyl ether, etc.) were unlikely to be activated by a free radical intermediate. The surface-stabilized ylide which has been proposed as an intermediate by many was studied to determine if in fact the ylide was stabilized. The total energy of the ylide was compared to that of the naked site on the zeolite and free methylene. Free methylene ranged, depending on the geometry of the ylide, between 50 and 80 kcal more stable. These numbers are qualitatively correct, but more electron correlation would have to be incorporated in the calculation to get an accurate value for the destabilization. Starting from a defect site, two CH[sub 2] groups were each attached to two oxygen atoms. It was thought that two CH[sub 2] groups would take up considerably more space than either than original Al atom or the four hydrogens. Molecular Mechanics calculations showed the zeolite to be sufficiently flexible to prevent crowding of the CH[sub 2]'s.

Miller, A.E.

1993-01-01T23:59:59.000Z

5

Homogeneous vs Heterogeneous Clustered Sensor Networks: A Comparative Study  

E-Print Network (OSTI)

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

Rosenberg, Catherine P.

6

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

E-Print Network (OSTI)

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

Boyer, Edmond

7

Application of solid ash based catalysts in heterogeneous catalysis  

SciTech Connect

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

Shaobin Wang [Curtin University of Technology, Perth, WA (Australia). Department of Chemical Engineering

2008-10-01T23:59:59.000Z

8

Forensic Tracking and Surveillance Algorithms for Homogeneous and Heterogeneous Settings  

E-Print Network (OSTI)

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

Sheldon, Nathan D.

9

Model heterogeneous acid catalysts and metal-support interactions: A combined surface science and catalysis study  

SciTech Connect

This (<100 [Angstrom]) silica-alumina layers were tested as potential model heterogeneous acid catalysts for combined surface science and catalysis studies. Three preparation methods were used: oxidation of r3 [times] r3 R30 Al/Si(111) structure in UHV; deposition on Si(lll) from aqueous solution; and argon ion beam sputter deposition in UHV. The homogeneous thin layers are amorphous, and the chemical environment of surface atoms is similar to that of Si, Al and oxygen atoms on high surface area acid catalysts. Since the ion beam-deposited thin layer of silica-alumina has the same composition as the target zeolite this deposition method is a promising tool to prepare model catalysts using practical catalyst targets. The silica-alumina layers are active in cumene cracking, a typical acid catalyzed reaction. In order to clearly distinguish background reactions and the acid catalyzed reaction at least 20 cm[sup 2] catalyst surface area is needed. Two series of model platinum-alumina catalysts were prepared in a combined UHV -- high pressure reactor cell apparatus by depositing alumina on polycrystalline Pt foil and by vapor depositing Pt on a thin alumina layer on Au. Both model surfaces have been prepared with and without chlorine. AES, CO desorption as well as methyl cyclopentane (MCP) hydrogenolysis studies indicate that the Pt surface area is always higher if a chlorination step is involved. Selectivity patterns in MCP ring opening on Pt-on-alumina'' and on alumina-on-Pt'' are different; only the former is a linear combination of selective and statistical ring opening. Product distribution, however, changes with coverage and reaction time. The properties of the two model catalyst systems and role of chlorine in MCP hydrogenolysis are also discussed.

Boszormenyi, I.

1991-05-01T23:59:59.000Z

10

Model heterogeneous acid catalysts and metal-support interactions: A combined surface science and catalysis study  

SciTech Connect

This (<100 {Angstrom}) silica-alumina layers were tested as potential model heterogeneous acid catalysts for combined surface science and catalysis studies. Three preparation methods were used: oxidation of r3 {times} r3 R30 Al/Si(111) structure in UHV; deposition on Si(lll) from aqueous solution; and argon ion beam sputter deposition in UHV. The homogeneous thin layers are amorphous, and the chemical environment of surface atoms is similar to that of Si, Al and oxygen atoms on high surface area acid catalysts. Since the ion beam-deposited thin layer of silica-alumina has the same composition as the target zeolite this deposition method is a promising tool to prepare model catalysts using practical catalyst targets. The silica-alumina layers are active in cumene cracking, a typical acid catalyzed reaction. In order to clearly distinguish background reactions and the acid catalyzed reaction at least 20 cm{sup 2} catalyst surface area is needed. Two series of model platinum-alumina catalysts were prepared in a combined UHV -- high pressure reactor cell apparatus by depositing alumina on polycrystalline Pt foil and by vapor depositing Pt on a thin alumina layer on Au. Both model surfaces have been prepared with and without chlorine. AES, CO desorption as well as methyl cyclopentane (MCP) hydrogenolysis studies indicate that the Pt surface area is always higher if a chlorination step is involved. Selectivity patterns in MCP ring opening on ``Pt-on-alumina`` and on ``alumina-on-Pt`` are different; only the former is a linear combination of selective and statistical ring opening. Product distribution, however, changes with coverage and reaction time. The properties of the two model catalyst systems and role of chlorine in MCP hydrogenolysis are also discussed.

Boszormenyi, I.

1991-05-01T23:59:59.000Z

11

Porous Metal–Organic Frameworks for Heterogeneous Biomimetic Catalysis  

Science Journals Connector (OSTI)

Homogeneous artificial metalloporphyrins can undergo catalytic deactivation via suicidal self-oxidation, which lowers their catalytic activity and sustainability relative to their counterparts in Nature. ... The 3D structure of [Zn2(HCOO)(FeIII(H2O)-TCPP)]·guest (7) is made up of layered network of FeIII-TCPP connected with binuclear Zn2(COO)4 paddle-wheel SBUs, and further linked by formate pillars to homogeneously coordinate with Zn2(COO)4 SBUs (Figure 4a). ... pillar linker DPNI to form a three-dimensional porous structure. ...

Min Zhao; Sha Ou; Chuan-De Wu

2014-02-06T23:59:59.000Z

12

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

SciTech Connect

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

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

1982-01-01T23:59:59.000Z

13

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

14

MCNP5 Validation for Criticality Calculations: Homogeneous and Heterogeneous Systems  

E-Print Network (OSTI)

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

Haviland, David

15

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

SciTech Connect

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

Orechwa, Y.; Su, S.F.

1982-01-01T23:59:59.000Z

16

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

E-Print Network (OSTI)

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

Somorjai Ed., G.A.

2007-01-01T23:59:59.000Z

17

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

E-Print Network (OSTI)

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

Somorjai Ed., G.A.

2007-01-01T23:59:59.000Z

18

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

19

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

E-Print Network (OSTI)

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

Somorjai Ed., G.A.

2007-01-01T23:59:59.000Z

20

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

E-Print Network (OSTI)

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

Witham, Cole

2010-01-01T23:59:59.000Z

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


21

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

E-Print Network (OSTI)

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

Somorjai Ed., G.A.

2007-01-01T23:59:59.000Z

22

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

23

Homogeneous Catalysis: Ultimate Selectivity  

Science Journals Connector (OSTI)

...explanation is that the economics are not good right now...aban-doned because of economics. Monsanto thinks the...significant by-product is methane, which may represent...syngas. Syngas made by steam reforming of natural gas con-tains...

THOMAS H. MAUGH II

1983-06-03T23:59:59.000Z

24

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

SciTech Connect

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

25

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

SciTech Connect

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

Gerhard Strydom; Su-Jong Yoon

2014-04-01T23:59:59.000Z

26

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

27

HETEROGENEOUS CATALYSIS RESEARCH MEETING  

E-Print Network (OSTI)

character- ""'''"'"" ultra-high vacuum (UHV) conditions.To of ESR UHV techniques, which we shall various clean gasesheart of the design is UHV- ESR resonant microwave cavity

Authors, Various

2011-01-01T23:59:59.000Z

28

HETEROGENEOUS CATALYSIS RESEARCH MEETING  

E-Print Network (OSTI)

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

Authors, Various

2011-01-01T23:59:59.000Z

29

catalysis | EMSL  

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

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

30

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

SciTech Connect

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

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

1982-01-01T23:59:59.000Z

31

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

32

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

33

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

E-Print Network (OSTI)

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

Paris-Sud XI, Université de

34

Homogeneous Catalysis in Supercritical Fluids  

Science Journals Connector (OSTI)

...structure similar to a [2Fe-2S]-type iron-sulfur center. Previ-ously predicted...11. The 2 binding site contains heme a3 iron and copper atoms (CUB) with an interatomic...is no detectable bridging ligand between iron and copper atoms in spite of a strong antifer-romagnetic...

Philip G. Jessop; Takao Ikariya; Ryoji Noyori

1995-08-25T23:59:59.000Z

35

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

SciTech Connect

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

Hua, I.

1998-06-01T23:59:59.000Z

36

Biodiesel production from Stauntonia chinensis seed oil (waste from food processing): Heterogeneous catalysis by modified calcite, biodiesel purification, and fuel properties  

Science Journals Connector (OSTI)

Abstract In the present research, the potential of Stauntonia chinensis (SC) seed oil obtained from processing waste was investigated for the first time as biodiesel feedstock, including physicochemical properties of the oil, the heterogeneous catalysis process, purification, and fuel properties. A 29.37 ± 0.64 wt.% of oil content and 2.41 mg KOH/g of acid value was found. Under the optimised reaction conditions in the presence of modified calcite, an 88.02% of yield and a 98.90 wt.% of FAME content were achieved. According to EN 14124 (2012), SC biodiesel exhibited superior fuel properties compared to the most of other feedstock oils since it had an ideal fatty acid composition (low Cn:0 (8.06 wt.%), high Cn:1 (80.16 wt.%), and low Cn:2,3 (8.45 wt.%)). It was absolutely vital that the use of SC seed oil as a biodiesel feedstock would not compete with its use in food. In summary, SC seed oil should be recommended as a promising feedstock for biodiesel.

Rui Wang; Lili Sun; Xiaolin Xie; Lizhi Ma; Zhigang Liu; Xiaoyan Liu; Ning Ji; Guofang Xie

2014-01-01T23:59:59.000Z

37

Support Vector Machines for Predictive Modeling in Heterogeneous Catalysis:? A Comprehensive Introduction and Overfitting Investigation Based on Two Real Applications  

Science Journals Connector (OSTI)

The SVM methodology is evaluated using experimental data derived from exploration/optimization of heterogeneous catalysts in two different industrial fields:? oil refining and petrochemistry, the selected reactions for each application being n-alkane isomerization in gasoline and olefin epoxidation. ... However, the parameters' setting is independent of the benchmark, and a way to characterize the mostly unknown real search space for comparison with the benchmarks remains to be found. ... One should always test its methodology on benchmarks, since different levels of complexity can be artificially created, and the cost of experiments is null. ...

L. A. Baumes; J. M. Serra; P. Serna; A. Corma

2006-05-13T23:59:59.000Z

38

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

39

EMSL - catalysis  

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

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

40

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.

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

Reaction Selectivity in Heterogeneous Catalysis  

E-Print Network (OSTI)

of ultrahigh vacuum (UHV) surface science techniques.low pressure probes typical of UHV surface science. At thesecan be employed in-situ from UHV pressures to above ambient

Somorjai, Gabor A.

2010-01-01T23:59:59.000Z

42

INSTITUTE FOR INTEGRATED CATALYSIS Catalysis Research for  

E-Print Network (OSTI)

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

43

Organotextile Catalysis  

Science Journals Connector (OSTI)

...1242196 Ji-Woong Lee Thomas Mayer-Gall Klaus Opwis Choong Eui Song Jochen Stefan Gutmann Benjamin List 1Max-Planck-Institut...Catalysis Ji-Woong Lee, Thomas Mayer-Gall, Klaus Opwis, Choong Eui Song, Jochen Stefan Gutmann, Benjamin List Materials/Methods...

Ji-Woong Lee; Thomas Mayer-Gall; Klaus Opwis; Choong Eui Song; Jochen Stefan Gutmann; Benjamin List

2013-09-13T23:59:59.000Z

44

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

SciTech Connect

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

45

Relativistic effects in homogeneous gold catalysis  

Science Journals Connector (OSTI)

... Int. Edn 45, 2901–2904 (2006) Furstner, A. & Hannen, P. Carene terpenoids by gold-catalyzed cycloisomerization reactions. Chem. Commun. 2546–2547 (2004) Furstner, ...

David J. Gorin; F. Dean Toste

2007-03-22T23:59:59.000Z

46

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)

47

Enzyme catalysis Enzyme catalysis is the catalysis of chemical reactions by  

E-Print Network (OSTI)

Enzyme catalysis Enzyme catalysis is the catalysis of chemical reactions by specialized proteins known as enzymes. Catalysis of biochemical reactions in the cell is vital due to the very low reaction rates of the uncatalysed reactions. The mechanism of enzyme catalysis is similar in principle to other

Cavanagh, John

48

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

SciTech Connect

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

49

Biodiesel production from algae by using heterogeneous catalysts: A critical review  

Science Journals Connector (OSTI)

Abstract The numerous challenges associated with declining fossil fuel reserves as energy sources, have accounted for a shift to biofuels as alternatives. However, transesterification of animal fats and edible vegetable oils using homogeneous acids and bases for biodiesel production is recently considered unsustainable by industries, particularly due to food versus fuel competition, and economic and environmental challenges associated with the feedstocks and catalyst systems, respectively. The paper therefore presents a critical review on the prospects of non-edible oil (i.e. algae oil) for biodiesel production via heterogeneous catalysis. It covers the advantages of algae oil exploitation over edible oil feedstocks, progress made in the oil extraction, available heterogeneous catalyst systems and reaction mechanisms, optimum transesterification conditions and the way forward. As the economic feasibility of biodiesel production from algae is supported by the valorization of glycerol as by-product, we have also highlighted key available heterogeneous catalysts to upgrade glycerol into more useful industrial products.

Ahmad Galadima; Oki Muraza

2014-01-01T23:59:59.000Z

50

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

51

EMSL - In situ catalysis  

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

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

52

The Catalysis of the Carbon Monoxide-Steam Reaction  

Science Journals Connector (OSTI)

...The Catalysis of the Carbon Monoxide-Steam Reaction F. J. Long K. W. Sykes The kinetics of the carbon monoxide-steam reaction occurring heterogeneously at...nearly unity, while that with respect to steam is correspondingly lowered; a slight...

1952-01-01T23:59:59.000Z

53

Fundamental Catalysis Research in Japan  

Science Journals Connector (OSTI)

Fundamental Catalysis Research in Japan ... Japan is one of the foremost nations in catalysis research. ... Dr. Horiuti responded with information on what he and other Japanese research workers were doing, and subsequently I decided to visit Japan to study catalysis during my sabbatical leave from New York University last spring. ...

JOHN HAPPEL

1966-05-30T23:59:59.000Z

54

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

55

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

56

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

57

Polyisobutylene as a Polymer Support for Homogeneous Catalysis  

E-Print Network (OSTI)

to one (-OCH 3 , -OH termini) or two (two -OH termini) equivalents of ligand or catalyst per mole of polymer. Linkers as shown in eq. 2 are not required but are sometimes used. MeO O OH n O or HO O OH nanioic polymerization MeO O OH n HO O OH n Me... and the SPhos Pd catalyst had a TOF that was 20-fold larger than that of a similar ligated Pd catalyst on SiO 2 . O(CH 22 O) P(Cy) 2 OMe MeO (Cy) 2 P 9 HO PH(Cy) 2 h 70 o C, 12 h l - Cs 2 O 3 , H 3 CN Ms(CH 22 O) n Ms n Cl N H O + 2 mol% Pd(OAc) 2...

Hongfa, Chayanant

2010-01-14T23:59:59.000Z

58

Phase selectively soluble polymer supports to facilitate homogeneous catalysis  

E-Print Network (OSTI)

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

Ortiz-Acosta, Denisse

2009-05-15T23:59:59.000Z

59

Fundamental studies of reactive intermediates in homogeneous catalysis  

SciTech Connect

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

Not Available

1993-10-01T23:59:59.000Z

60

Tomographic Characterization of Aquifer Heterogeneity  

E-Print Network (OSTI)

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

Lyle, Shane

2011-05-31T23:59:59.000Z

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

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.

62

DOE Catalysis Working Group Meeting  

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

PEMFC Performance and Durability - Jim Waldecker (Ford) 9:45 - 10:00 Degradation of Nanoparticle Pt alloy and De-alloyed Pt Catalysts - Debbie Myers (ANL) Catalysis Working Group...

63

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

E-Print Network (OSTI)

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

Wang, Qingqing

2012-07-16T23:59:59.000Z

64

Magnetic catalysis in flavored ABJM  

E-Print Network (OSTI)

We study the magnetic catalysis of chiral symmetry breaking in the ABJM Chern-Simons matter theory with unquenched flavors in the Veneziano limit. We consider a magnetized D6-brane probe in the background of a flavored black hole which includes the backreaction of massless smeared flavors in the ABJM geometry. We find a holographic realization for the running of the quark mass due to the dynamical flavors. We compute several thermodynamic quantities of the brane probe and analyze the effects of the dynamical quarks on the fundamental condensate and on the phase diagram of the model. The dynamical flavors have an interesting effect on the magnetic catalysis. At zero temperature and fixed magnetic field, the magnetic catalysis is suppressed for small bare quark masses whereas it is enhanced for large values of the mass. When the temperature is non-zero there is a critical magnetic field, above which the magnetic catalysis takes place. This critical magnetic field decreases with the number of flavors, which we interpret as an enhancement of the catalysis.

Niko Jokela; Alfonso V. Ramallo; Dimitrios Zoakos

2013-11-25T23:59:59.000Z

65

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.

66

Parameter Estimation Versus Homogenization Techniques in Time-Domain Characterization of Composite Dielectrics  

E-Print Network (OSTI)

Parameter Estimation Versus Homogenization Techniques in Time-Domain Characterization of Composite problem approach to parameter estimation with homogenization techniques for characterizing the electrical with heterogeneous micro-structures which are described by spatially periodic parameters. We also consider

67

Heterogeneous effects in fast breeder reactors  

E-Print Network (OSTI)

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

Gregory, Michael Vladimir

1973-01-01T23:59:59.000Z

68

Characterizing aquifer heterogeneity using hydraulic tomography  

E-Print Network (OSTI)

well-studied site in northeastern Kansas. A computer program has been developed to analyze the data by extending the 3D homogeneous spherical radial equation to the heterogeneous case. The analysis program is capable of efficiently resolving zones...

Wachter, Brian James

2008-07-29T23:59:59.000Z

69

Incorporating Green Chemistry Principles in Heterogeneous Catalysis Operations.  

E-Print Network (OSTI)

??Many commercial processes for the production of chemicals involve harsh organic solvents as well as numerous by-products that are detrimental to the environment. For many… (more)

Bacik, Deborah

2011-01-01T23:59:59.000Z

70

Charge Transfer and Support Effects in Heterogeneous Catalysis  

E-Print Network (OSTI)

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

Hervier, Antoine

2012-01-01T23:59:59.000Z

71

Heterogeneous Catalysis DOI: 10.1002/anie.201200699  

E-Print Network (OSTI)

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

Frenkel, Anatoly

72

SOUTHWEST CATALYSIS SOCIETY 2008 SPRING SYMPOSIUM  

E-Print Network (OSTI)

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

Natelson, Douglas

73

Transmural Catalysis - High Efficiency Catalyst Systems for NOx...  

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

Transmural Catalysis - High Efficiency Catalyst Systems for NOx Adsorbers and SCR Transmural Catalysis - High Efficiency Catalyst Systems for NOx Adsorbers and SCR Presentation...

74

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

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

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

75

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

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

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

76

BERKELEY CATALYSIS CENTER Monday October 13  

E-Print Network (OSTI)

of an industrial catalyst shaped by extrusion with alumina. The catalytic assessment took place with two reactionsBERKELEY CATALYSIS CENTER Seminar Monday October 13 The McCollum Room 775 Tan Hall 9:00 am Dr. Jean parrafinic feedstocks. It also illustrates the type of cooperation between industrial and academic catalysis

Iglesia, Enrique

77

"Nanocrystal bilayer for tandem catalysis"  

SciTech Connect

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

78

Magnetic Catalysis vs Magnetic Inhibition  

E-Print Network (OSTI)

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

Kenji Fukushima; Yoshimasa Hidaka

2012-09-06T23:59:59.000Z

79

Phase-Transfer Catalysis: Industrial Perspective  

Science Journals Connector (OSTI)

In the early 1990s, it was estimated that approximately 500 commercial phase-transfer catalysis (PTC) processes were being performed using at least 25 million pounds per year of catalyst. It was also estimated...

Charles M. Starks; Charles L. Liotta; Marc E. Halpern

1994-01-01T23:59:59.000Z

80

Basic Concepts in Phase-Transfer Catalysis  

Science Journals Connector (OSTI)

Phase-transfer catalysis (PTC) is a powerful tool in many areas of chemistry. It is a technique for conducting reactions between two or more reagents in two or more phases, when reaction is inhibited because t...

Charles M. Starks; Charles L. Liotta; Marc E. Halpern

1994-01-01T23:59:59.000Z

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.


81

Catalysis Working Group Meeting: June 2014  

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

Agenda and presentations from the Catalysis Working Group held on June 16, 2014, in Washington, D.C., in conjunction with the DOE Hydrogen and Fuel Cells Program Annual Merit Review and Peer Evaluation Meeting.

82

Single-molecule kinetics of nanoparticle catalysis  

Science Journals Connector (OSTI)

Owing to their structural dispersion, the catalytic properties of nanoparticles are challenging to characterize in ensemble-averaged measurements. The single-molecule approach enables studying the catalysis of na...

Weilin Xu; Hao Shen; Guokun Liu; Peng Chen

2009-12-01T23:59:59.000Z

83

Synthesis of Biodiesel via Acid Catalysis  

Science Journals Connector (OSTI)

Synthesis of Biodiesel via Acid Catalysis ... Biodiesel is synthesized via the transesterification of lipid feedstocks with low molecular weight alcohols. ... Nonetheless, acid-catalyzed processes could produce biodiesel from low-cost feedstocks, lowering production costs. ...

Edgar Lotero; Yijun Liu; Dora E. Lopez; Kaewta Suwannakarn; David A. Bruce; James G. Goodwin, Jr.

2005-01-25T23:59:59.000Z

84

Molecularly engineering homogenous catalysts  

E-Print Network (OSTI)

have developed new strategies for homogeneous catalyst recovery. Poly (N-isopropylacrylamide) and poly (N-octadecylacrylamide) supports, for example, yield recoverable catalysts that are selectively soluble in the lower (polar) phase and the upper (non...

Hughes, Reagan Rebekah

2013-02-22T23:59:59.000Z

85

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

SciTech Connect

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

86

Transport Upscaling of Adsorbing Solutes in Heterogeneous Media  

E-Print Network (OSTI)

Transport Upscaling of Adsorbing Solutes in Heterogeneous Media #12;Transport in a Homogeneous adsorbed phases. � Apparent adsorption times = r u measured in units u 17 #12;� Adsorption rate = u

Politècnica de Catalunya, Universitat

87

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

SciTech Connect

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

Khalil, H.; Yarlagadda, B.S.

1984-01-01T23:59:59.000Z

88

Homogeneous and Heterogeneous M l i / M PMulticore / Manycore Processors,  

E-Print Network (OSTI)

Electronics (Embedded) Mobile Phone, Game, TV, Car Navigation, Camera, IBM/ Sony/ Toshiba Cell, Fujitsu FR1000 & Highend Servers IBM(Power4,5,6,7), Sun (SparcT1,T2), Fujitsu SPARC64fx8 Supercomputers Earth Simulator:40 (Leader: Prof.Kasahara) , , p BG/Q (A2:16cores) Water Cooled20PFLOPS, 3-4MW (2011-12), BlueWaters

Kasahara, Hironori

89

Research in Kasahara & Kimura Lab. Homogeneous and Heterogeneous  

E-Print Network (OSTI)

.Kasahara) , , p BG/Q (A2:16cores) Water Cooled20PFLOPS, 3-4MW (2011-12), BlueWaters(HPCS) Power7, 10 PFLOP+(2011, Game, TV, Car Navigation, Camera, IBM/ Sony/ Toshiba Cell, Fujitsu FR1000, Panasonic Uniphier, NEC Deskside & Highend ServersOSCAR Type Multi-core Chip by Renesas in WSs, Deskside & Highend Servers IBM(Power

Kasahara, Hironori

90

Catalysis Working Group Kick-Off Meeting Agenda  

Office of Environmental Management (EM)

1 Catalysis Working Group 2012 Hydrogen and Fuel Cells Program Annual Merit Review and Peer Evaluation Meeting Arlington, VA - May 14, 2012 Catalysis Working Group Kick-off Meeting...

91

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.

92

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

93

Functional Networks of Organic and Coordination Polymers: Catalysis of Fructose Conversion  

Science Journals Connector (OSTI)

All chemicals and solvents used were obtained from Sigma-Aldrich Chemical Co. and were of the highest purity available. ... To elucidate the utility of the stable, porous and functional composite materials developed in this work, we focused on the heterogeneous catalysis of the conversion of a biosourced substrate, fructose, into 5-hydroxymethylfurfural (HMF), one of the most important platform molecules for, for example, liquid biofuel and polyester production (SI Figure S10). ... Physical Chemistry Chemical Physics (2012), 14 (40), 13914-13917 CODEN: PPCPFQ; ISSN:1463-9076. ...

Lev Bromberg; Xiao Su; T. Alan Hatton

2014-10-23T23:59:59.000Z

94

An FFT-based Galerkin method for homogenization of periodic media  

Science Journals Connector (OSTI)

In 1994, Moulinec and Suquet introduced an efficient technique for the numerical resolution of the cell problem arising in homogenization of periodic media. The scheme is based on a fixed-point iterative solution to an integral equation of the Lippmann-Schwinger ... Keywords: Conjugate gradients, Fourier transform, Galerkin approximation, Heterogeneous media, Numerical homogenization, Trigonometric polynomials

Jaroslav Vond?ejc, Jan Zeman, Ivo Marek

2014-08-01T23:59:59.000Z

95

Cryogenic homogenization of biological tissues  

Science Journals Connector (OSTI)

Cryogenic homogenization of biological tissues ... Thermal (roasting and heating in a microwave oven), mechanical (milling and cryogenic grinding), and enzymatic ... ...

Rolf Zeisler; John K. Langland; Sally H. Harrison

1983-12-01T23:59:59.000Z

96

Synthesis and applications of imidazolium-based ionic liquids and their polymer derivatives .  

E-Print Network (OSTI)

??"Imidazolium-based ionic liquids have been increasingly used as green solvents to replace the volatile and relatively toxic organic solvents, in homogeneous and heterogeneous catalysis, materials… (more)

Oh, Woon Su, 1974-

2012-01-01T23:59:59.000Z

97

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

98

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

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

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

99

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

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

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

100

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

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

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

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

Center for Biological Electron Transfer and Catalysis (BETCy...  

Office of Science (SC) Website

Center for Biological Electron Transfer and Catalysis (BETCy) Energy Frontier Research Centers (EFRCs) EFRCs Home Centers EFRC External Websites Research Science Highlights News &...

102

"Seeing" hydrogen atoms to unveil enzyme catalysis | ornl.gov  

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

"Seeing" hydrogen atoms to unveil enzyme catalysis Image shows nuclear density maps in the active site of DHFR where the catalytic group Asp27 and substrate folate have...

103

University of Delaware | Catalysis Center for Energy Innovation...  

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

Modeling Activity map produced from the new high-throughput computational engine. Example for ethylene glycol catalysis. Reforming, hydrodeoxygenation, dehydrogenation, and...

104

Effective permeabilities for model heterogeneous porous media  

SciTech Connect

This paper presents a technique to evaluate effective absolute permeabilities for heterogeneous porous media. The technique is based on a perturbation analysis of the equations of motion of a slightly compressible fluid in a homogeneous porous medium at low Reynolds numbers. The effective permeabilities can be calculated once the local geometry of the heterogeneous medium is specified. The technique is used to evaluate two- and three-dimensional effective vertical permeabilities in porous media with shale intercalations, including the case in which the porous matrix is anisotropic.

Otevo, C.; Rusinek, I. (Tecnologiade Yacimientos, INTEVEPS.A., P.O. Box 76343, Caracas 1070-A (VE)); Saez, A.E. (Departamento de Termodinamicay Fenomenosde Transferencia, Universidad Simon Bolivar, P.O. Box 89000, Caracas 1086-A (VE))

1990-01-01T23:59:59.000Z

105

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

E-Print Network (OSTI)

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

Chakravarthy, Deepak

2005-08-29T23:59:59.000Z

106

Microgrids and Heterogeneous Power Quality and Reliability  

SciTech Connect

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

107

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.

108

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

E-Print Network (OSTI)

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

Pennycook, Steve

109

Supported Molten Metal Catalysis. A New Class of Catalysts  

SciTech Connect

We describe a new class of heterogeneous catalysts called supported molten metal catalysis (SMMC), in which molten metal catalysts are dispersed as nanodroplets on the surface of porous supports, allowing much larger active surface area than is possible in conventional contacting techniques for catalytic metals that are molten under reaction conditions, thus greatly enhancing their activity and potential utility. Specific examples of different types of reactions are provided to demonstrate the broad applicability of the technique in designing active, selective, and stable new catalysts. It is shown that dispersing the molten metal on a support in the suggested manner can enhance the rate of a reaction by three to four orders of magnitude as a result of the concomitant increase in the active surface area. New reaction examples include {gamma}-Al{sub 2}O{sub 3} supported molten Te (melting point 450 C) and Ga (MP 30 C) catalysts for bifunctional methylcyclohexane dehydrogenation. These catalysts provide activity similar to conventional Pt-based catalysts for this with better resistance to coking. In addition, results are described for a controlled pore glass supported molten In (MP 157 C) catalyst for the selective catalytic reduction of NO with ethanol in the presence of water, demonstrating activities superior to conventional catalysts for this reaction. A discussion is also provided on the characterization of the active surface area and dispersion of these novel supported catalysts. It is clear based on the results described that the development of new active and selective supported molten metal catalysts for practical applications is entirely plausible.

Ravindra Datta; Ajeet Singh; Manuela Serban; Istvan Halasz

2006-06-02T23:59:59.000Z

110

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

Science Journals Connector (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

111

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

E-Print Network (OSTI)

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

Mahajan, Vinay Subhash

2009-01-01T23:59:59.000Z

112

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

113

Experimental evidence of foam homogenization  

SciTech Connect

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

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

2012-11-15T23:59:59.000Z

114

A quantitative measure for protein conformational heterogeneity  

Science Journals Connector (OSTI)

Conformational heterogeneity is a defining characteristic of proteins. Intrinsically disordered proteins (IDPs) and denatured state ensembles are extreme manifestations of this heterogeneity. Inferences regarding globule versus coil formation can be drawn from analysis of polymeric properties such as average size shape and density fluctuations. Here we introduce a new parameter to quantify the degree of conformational heterogeneity within an ensemble to complement polymeric descriptors. The design of this parameter is guided by the need to distinguish between systems that couple their unfolding-folding transitions with coil-to-globule transitions and those systems that undergo coil-to-globule transitions with no evidence of acquiring a homogeneous ensemble of conformations upon collapse. The approach is as follows: Each conformation in an ensemble is converted into a conformational vector where the elements are inter-residue distances. Similarity between pairs of conformations is quantified using the projection between the corresponding conformational vectors. An ensemble of conformations yields a distribution of pairwise projections which is converted into a distribution of pairwise conformational dissimilarities. The first moment of this dissimilarity distribution is normalized against the first moment of the distribution obtained by comparing conformations from the ensemble of interest to conformations drawn from a Flory random coil model. The latter sets an upper bound on conformational heterogeneity thus ensuring that the proposed measure for intra-ensemble heterogeneity is properly calibrated and can be used to compare ensembles for different sequences and across different temperatures. The new measure of conformational heterogeneity will be useful in quantitative studies of coupled folding and binding of IDPs and in de novo sequence design efforts that are geared toward controlling the degree of heterogeneity in unbound forms of IDPs.

Rohit V. Pappu

2013-01-01T23:59:59.000Z

115

Catalysis Working Group Kick-Off Meeting: May 2012  

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

Information from the Catalysis Working Group kick-off meeting held May 14, 2012, in Arlington, Virginia, in conjunction with the DOE Hydrogen and Fuel Cells Program Annual Merit Review and Peer Evaluation Meeting.

116

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

117

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

Energy Savers (EERE)

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

118

Phase-Transfer Catalysis Reaction with Strong Bases  

Science Journals Connector (OSTI)

Among the vast scope of phase-transfer catalysis (PTC) applications, the largest sector involves the reaction of anions that are reacted and/or generated under PTC conditions with species containing electrophi...

Charles M. Starks; Charles L. Liotta; Marc E. Halpern

1994-01-01T23:59:59.000Z

119

Phase-Transfer Catalysis Displacement Reactions with Simple Anions  

Science Journals Connector (OSTI)

Phase-transfer catalysis (PTC) is an excellent technique both in liquid—liquid and liquid—solid (and sometimes in liquid—vapor) modes for conducting displacement reactions with anions.

Charles M. Starks; Charles L. Liotta; Marc E. Halpern

1994-01-01T23:59:59.000Z

120

Experiments and analysis for an axially heterogeneous LMR assembly at ZPPR  

SciTech Connect

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

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

1988-01-01T23:59:59.000Z

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

Nanoscale Advances in Catalysis and Energy Applications  

E-Print Network (OSTI)

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

Li, Yimin

2011-01-01T23:59:59.000Z

122

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

E-Print Network (OSTI)

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

Obradovic, Zoran

123

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

E-Print Network (OSTI)

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

Vucetic, Slobodan

124

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… (more)

Blaylock, Donnie Wayne

2011-01-01T23:59:59.000Z

125

The societal significance of catalysis and the growing practical importance of single-site heterogeneous catalysts  

Science Journals Connector (OSTI)

...that these sites have the same energy and same environment. (Thomas...colour.) Figure 3. Computed energy levels of outermost electrons...functional theory calculated energies, for the epoxidation of an...feedstocks typical products reference corn adipic acid Thomas et al...

2012-01-01T23:59:59.000Z

126

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

127

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

E-Print Network (OSTI)

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

Taha Sochi

2010-12-20T23:59:59.000Z

128

The societal significance of catalysis and the growing practical importance of single-site heterogeneous catalysts  

Science Journals Connector (OSTI)

...However, the pores themselves...diameters of the pores leading into...because of size and shape...catalytic conversion of methanol to ethylene and propylene (Chen Thomas...typified by zeolites, ALPOs...diameter of the pores may be so...fundamental study and deeper...fact that small fragments...

2012-01-01T23:59:59.000Z

129

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.

130

Some General Themes in Catalysis at LANL  

SciTech Connect

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

131

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

132

Synthesis of Co oxide doped carbon aerogel catalyst and catalytic performance in heterogeneous oxidation of phenol in water  

Science Journals Connector (OSTI)

Co oxide doped carbon aerogel (Co/CA) was prepared, characterised by several techniques, and tested for heterogeneous oxidation of phenol in aqueous solution using oxone as an oxidant. For a comparison, homogeneous oxidation of phenol in Co2+/oxone was also investigated. It was found that homogeneous oxidation of phenol using Co2+/oxone was more effective than Co2+/H2O2 and homogeneous oxidation was faster than heterogeneous Co/CA–oxone. Heterogeneous oxidation of phenol in Co/CA–oxone system followed first order kinetics and the activation energy of the heterogeneous system was estimated to be 62.9 kJ/mol. Several factors influencing phenol degradation in the heterogeneous oxidation were studied. Co/CA loading played a more important role in phenol degradation than oxone concentration, and the presence of other organics in solution resulted in a lower phenol oxidation.

Yasnessya Hardjono; Hongqi Sun; Huyong Tian; C.E. Buckley; Shaobin Wang

2011-01-01T23:59:59.000Z

133

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

SciTech Connect

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

Metiu, Horia [University of California, Santa Barbara

2014-08-22T23:59:59.000Z

134

Single-Molecule Kinetics of Nanoparticle Catalysis , Hao Shen, Guokun Liu, and Peng Chen  

E-Print Network (OSTI)

#12;Single-Molecule Kinetics of Nanoparticle Catalysis Weilin Xu , Hao Shen, Guokun Liu, and Peng to characterize in ensemble-averaged measurements. The single-molecule approach enables studying the catalysis single-molecule Áuorescence studies of single Au-nanoparticle catalysis, focusing on the theoretical

Chen, Peng

135

Heterogeneous actor modeling  

Science Journals Connector (OSTI)

Complex systems demand diversity in the modeling mechanisms. This "roadmap" paper prescribes an approach to modeling based on concurrent communicating components actors), where a diversity of orchestration strategies govern the execution and interaction ... Keywords: heterogeneity, models of computation, ptolemy

Edward A. Lee

2011-10-01T23:59:59.000Z

136

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,

137

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

138

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

139

Lorentzian homogeneous spaces admitting a homogeneous structure of type T1+T3  

E-Print Network (OSTI)

We show that a Lorentzian homogeneous space admitting a homogeneous structure of type T1 + T3 is either a (locally) symmetric space or a singular homogeneous plane wave.

P. Meessen

2005-04-07T23:59:59.000Z

140

Coherence delay augmented laser beam homogenizer  

DOE Patents (OSTI)

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

Rasmussen, P.; Bernhardt, A.

1993-06-29T23:59:59.000Z

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


141

Coherence delay augmented laser beam homogenizer  

DOE Patents (OSTI)

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

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

1993-01-01T23:59:59.000Z

142

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

SciTech Connect

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

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

1989-11-01T23:59:59.000Z

143

Origins of catalysis by computationally designed retroaldolase enzymes  

E-Print Network (OSTI)

Origins of catalysis by computationally designed retroaldolase enzymes Jonathan K. Lassilaa , David enzymes with the goal of understanding the extent and the origins of their catalytic power. Direct comparison of the designed enzymes to primary amine catalysts in solution revealed a rate acceleration of 105

Herschlag, Dan

144

Solar Energy without Neutrinos: Fusion Catalysis by Quarks  

Science Journals Connector (OSTI)

... some features of fusion catalysis by quarks and the consequences relating to release of stellar energy. In particular, the recent non-observation8 of ... . In particular, the recent non-observation8 of solar neutrinos which rules out9-12 the carbon cycle as the main mechanism for ...

L. MARSHALL LIBBY; F. J. THOMAS

1969-06-28T23:59:59.000Z

145

Frontiers in Catalysis Science and Engineering Seminar Series  

E-Print Network (OSTI)

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

146

Catalysis in the preparation of fragrances and flavours  

Science Journals Connector (OSTI)

This review, with more than 250 references in the field of fragrance and flavour chemistry, summarises recent progress in industrial catalysis. Applications in classical reactions, such as hydrogenations, isomerisations, hydride reductions, oxidations, hydroformylations, metathesis, aldol and Friedel–Crafts condensations in achiral, racemic and asymmetric fashion are discussed.

Christian Chapuis; Denis Jacoby

2001-01-01T23:59:59.000Z

147

A Single-Molecule Study of RNA Catalysis and Folding  

E-Print Network (OSTI)

A Single-Molecule Study of RNA Catalysis and Folding Xiaowei Zhuang,1 * Laura E. Bartley,2 * Hazen and undocks from the ribozyme core was observed directly in single-molecule time trajectories, allowing. These results establish single-molecule fluorescence as a pow- erful tool for examining RNA folding. Virtually

Herschlag, Dan

148

Overview of surface science and catalysis by Qifei Wu  

E-Print Network (OSTI)

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

149

Heterogeneous electrocatalysis in porous cathodes of solid oxide fuel cells  

E-Print Network (OSTI)

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

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

2014-01-01T23:59:59.000Z

150

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

SciTech Connect

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

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

2014-11-01T23:59:59.000Z

151

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

E-Print Network (OSTI)

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

Ahosseini, Azita

152

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

153

Distinguishing features of flow in heterogeneous porous media: 4, Is a more general dynamic description required  

SciTech Connect

Groundwater theory that applies to only homogeneous systems is often too restricted to adequately solve actual groundwater pollution problems. For adequate solutions, the more general theory for heterogeneous porous systems is needed. However, the present dynamic and kinematic descriptions in heterogeneous materials have evolved largely from the restricted and less general homogeneous theory. These descriptions are inadequate because they fail to account for all the energy dissipation in the system. The basic distinguishing dynamic feature of heterogeneous flow theory from the less general homogeneous-based theory is the macroscopic rotational flow component. Specifically, existence of rotational flow components and their independence from the translational flow components are the necessary and sufficient conditions that completely differentiate between the complex lamellar heterogeneous flow theory and the simpler lamellar flow of homogeneous theory. This paper proposes a more general dynamic form of the flow equation to include the added rotational dissipation that is missing from the present Darcian description of flow in heterogeneous media. 31 refs.

Nelson, R.W.

1990-11-01T23:59:59.000Z

154

A New Scanning Tunneling Microscope Reactor Used for High Pressure and High Temperature Catalysis Studies  

SciTech Connect

We present the design and performance of a home-built high-pressure and high-temperature reactor equipped with a high-resolution scanning tunneling microscope (STM) for catalytic studies. In this design, the STM body, sample, and tip are placed in a small high pressure reactor ({approx}19 cm{sup 3}) located within an ultrahigh vacuum (UHV) chamber. A sealable port on the wall of the reactor separates the high pressure environment in the reactor from the vacuum environment of the STM chamber and permits sample transfer and tip change in UHV. A combination of a sample transfer arm, wobble stick, and sample load-lock system allows fast transfer of samples and tips between the preparation chamber, high pressure reactor, and ambient environment. This STM reactor can work as a batch or flowing reactor at a pressure range of 10{sup -13} to several bars and a temperature range of 300-700 K. Experiments performed on two samples both in vacuum and in high pressure conditions demonstrate the capability of in situ investigations of heterogeneous catalysis and surface chemistry at atomic resolution at a wide pressure range from UHV to a pressure higher than 1 atm.

Tao, Feng; Tang, David C.; Salmeron, Miquel; Somorjai, Gabor A.

2008-05-12T23:59:59.000Z

155

Pacific Northwest National Laboratory Catalysis Highlights for FY2007  

SciTech Connect

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

156

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

Office of Science (SC) Website

Catalysis Center for Energy Innovation (CCEI) Energy Frontier Research Centers (EFRCs) EFRCs Home Centers EFRC External Websites Research Science Highlights News & Events...

157

Homogeneous catalysts in hypersonic combustion  

SciTech Connect

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

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

1989-01-01T23:59:59.000Z

158

MORLEY RANK IN HOMOGENEOUS MODELS ALEXEI KOLESNIKOV  

E-Print Network (OSTI)

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

Kolesnikov, Alexei

159

Wetting of rough surfaces: a homogenization approach  

Science Journals Connector (OSTI)

...plane xd = 0, and it is rough at a scale , where is...A (2005) Wetting of rough surfaces: a homogenization...where S1 is a closed set in Rd such that {xd 0...is finite, then L is a set with finite perimeter...A (2005) Wetting of rough surfaces: a homogenization...

2005-01-01T23:59:59.000Z

160

Monodisperse Platinum and Rhodium Nanoparticles as Model Heterogeneous Catalysts  

SciTech Connect

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

Coble, Inger M

2008-08-15T23:59:59.000Z

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

Chapter 22 - Heterogeneous Catalytic Reduction for Water Purification: Nanoscale Effects on Catalytic Activity, Selectivity, and Sustainability  

Science Journals Connector (OSTI)

Reductive catalysis is a promising water treatment technology that employs heterogeneous metal catalysts (e.g., Pd nanoparticles on a support) to convert dihydrogen to adsorbed atomic hydrogen in order to promote reactions with functional groups in various contaminants. Reductive catalysis has several potential advantages, including high selectivity for a given target, fast rates under mild conditions, and low production of harmful by-products. The technology has been applied mostly for remediation of groundwater contaminated with halogenated hydrocarbons and for treatment of nitrate, but recent studies have expanded the range of target contaminants to include perchlorate and N-nitrosamines. Palladium-based catalysts hold tremendous promise for their ability to selectively destroy several drinking water contaminants, and some compounds that exhibit slow reaction kinetics with Pd alone are rapidly degraded when a second, promoter metal is added to the catalyst. However, there is a lack of information about the long-term sustainability of these catalytic treatment processes, which is a major consideration in their possible adoption for remediation applications. Recent research has focused on the nanoscale characterization of these heterogeneous catalysts in order to develop an improved understanding of their mechanisms of deactivation and the pathways for regeneration. Two examples of studies from the authors’ laboratories, involving (i) hydrodehalogenation of iodinated X-ray contrast media with Ni or Pd catalysts and (ii) selective reduction of nitrate with a regenerable Pd-In/alumina catalyst, are discussed in this chapter.

Timothy J. Strathmann; Charles J. Werth; John R. Shapley

2014-01-01T23:59:59.000Z

162

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

SciTech Connect

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

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

2010-03-16T23:59:59.000Z

163

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

E-Print Network (OSTI)

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

164

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

E-Print Network (OSTI)

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

Kaiser, Ralf I.

2010-01-01T23:59:59.000Z

165

Application of Atmospheric Non Thermal Plasma-Catalysis Hybrid System for Air Pollution Control: Toluene removal.  

E-Print Network (OSTI)

1 Application of Atmospheric Non Thermal Plasma-Catalysis Hybrid System for Air Pollution Control for these technologies. As an alternative to conventional VOCs abatement techniques, atmospheric non-thermal plasma (NTP rue d'Issoudun, BP 6744, 45067 Orléans Cedex 02, France. Keywords: Non thermal Plasma, Catalysis

Paris-Sud XI, Université de

166

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

167

Inorganic Chemistry in Hydrogen Storage and Biomass Catalysis  

SciTech Connect

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

168

Hydrogen catalysis and scavenging action of Pd-POSS nanoparticles  

SciTech Connect

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

169

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

170

Dynamical heterogeneities in an attraction driven colloidal glass  

E-Print Network (OSTI)

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

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

2005-10-17T23:59:59.000Z

171

Application of cryogenic grinding to achieve homogenization of transuranic wastes  

SciTech Connect

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

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

1996-08-01T23:59:59.000Z

172

Runtime Adaptation for Autonomic Heterogeneous Computing | ornl...  

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

caching, OS noise, and a myriad of other factors. As heterogeneity becomes a fact of life at every level of computing, efficiently managing heterogeneous compute resources is...

173

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.

174

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

175

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

176

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.

177

Metal Carbonyl-Hydrosilane Reactions and Hydrosilation Catalysis  

SciTech Connect

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

Cutler, A. R.

2001-04-14T23:59:59.000Z

178

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

179

On Twisted homogeneous racks of type D  

E-Print Network (OSTI)

We develop some techniques to check when a twisted homogeneous rack of class (L,t,\\theta) is of type D. Then we apply the obtained results to the cases L an alternating group on n letters, n\\geq 5, or L a sporadic group.

Andruskiewitsch, N; Garcia, G A; Vendramin, L

2010-01-01T23:59:59.000Z

180

Homogeneous quasimorphisms on the symplectic linear group  

E-Print Network (OSTI)

obtain |(g) + (g-1 )| C/k for every k and so (g-1 ) = -(g). Hence (ghg-1 ) - (h) = (ghg-1 ) - (g) - (h) - (g-1 ) 2C. Using homogeneity again we obtain (ghg-1 ) = (h) for all g, h G. Proof of Theorem 1. Let

Salamon, Dietmar A.

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

ANDREA BRAIDES Homogenization of Lattice Systems  

E-Print Network (OSTI)

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

Braides, Andrea

182

A Homogenized Energy Framework for Ferromagnetic Hysteresis  

E-Print Network (OSTI)

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

183

337th Catalysis Research Center (CRC) Colloquium Fluorine Industry in China  

E-Print Network (OSTI)

337th Catalysis Research Center (CRC) Colloquium Fluorine Industry in China Lu Long (Shanghai, Central Research & Development, Experimental Station, DuPont Company, USA 1994.9 to1996.9 Postdoctoral

Ishii, Hitoshi

184

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

E-Print Network (OSTI)

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

Ryu, Youngha

2005-08-29T23:59:59.000Z

185

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

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

The Bioenergy Technologies Office works with industry to develop pathways that use heat, pressure, and catalysis to convert domestic, non-food biomass into gasoline, jet fuel, and other products.

186

Variables in Reaction Design for Laboratory and Industrial Applications of Phase-Transfer Catalysis  

Science Journals Connector (OSTI)

Many factors, known and unknown, contribute to the effective selection of a catalyst and other conditions for a given phase-transfer catalysis (PTC) application. Therefore, no simple single guideline exists fo...

Charles M. Starks; Charles L. Liotta; Marc E. Halpern

1994-01-01T23:59:59.000Z

187

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

188

Continuous-time random-walk model of transport in variably saturated heterogeneous porous media  

Science Journals Connector (OSTI)

We propose a unified physical framework for transport in variably saturated porous media. This approach allows fluid flow and solute migration to be treated as ensemble averages of fluid and solute particles, respectively. We consider the cases of homogeneous and heterogeneous porous materials. Within a fractal mobile-immobile continuous time random-walk framework, the heterogeneity will be characterized by algebraically decaying particle retention times. We derive the corresponding (nonlinear) continuum-limit partial differential equations and we compare their solutions to Monte Carlo simulation results. The proposed methodology is fairly general and can be used to track fluid and solutes particles trajectories for a variety of initial and boundary conditions.

Andrea Zoia; Marie-Christine Néel; Andrea Cortis

2010-03-04T23:59:59.000Z

189

Quantum Memory with a controlled homogeneous splitting  

E-Print Network (OSTI)

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

Hétet, G; Chanelière, T

2013-01-01T23:59:59.000Z

190

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

191

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

192

Heterogeneous nucleation of/on nanoparticles: a density functional study using the phase-field crystal model  

E-Print Network (OSTI)

Crystallization of supersaturated liquids usually starts by heterogeneous nucleation. Mounting evidence shows that even homogeneous nucleation in simple liquids takes place in two steps; first a dense amorphous precursor forms, and the crystalline phase appears via heterogeneous nucleation in/on the precursor cluster. Herein, we review recent results by a simple dynamical density functional theory, the phase-field crystal model, for (precursor-mediated) homogeneous and heterogeneous nucleation of nanocrystals. It will be shown that the mismatch between the lattice constants of the nucleating crystal and the substrate plays a decisive role in determining the contact angle and nucleation barrier, which were found to be non-monotonic functions of the lattice mismatch. Time dependent studies are essential as investigations based on equilibrium properties often cannot identify the preferred nucleation pathways. Modeling of these phenomena is essential for designing materials on the basis of controlled nucleation and/or nano-patterning.

László Gránásy; Frigyes Podmaniczky; Gyula I. Tóth; György Tegze; Tamás Pusztai

2014-07-14T23:59:59.000Z

193

Molecular-level Design of Heterogeneous Chiral Catalysts  

SciTech Connect

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

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

2013-04-28T23:59:59.000Z

194

Global Thermodynamic Atmospheric Modeling: Search for NewHeterogeneous Reactions  

SciTech Connect

This article demonstrates quantitatively how far reactions are from chemical equilibrium over the full space of a two-dimensional atmospheric model. This method could be used with data where an instrument-equipped aircraft measures numerous species simultaneously, An atmospheric reaction is displaced from equilibrium by solar radiation and relocation of species by atmospheric motions. One purpose of this study is to seek additional stratospheric or tropospheric gas-phase chemical reactions that might undergo heterogeneous catalysis. Hypothetical cases can be rapidly screened in terms of their thermodynamic potential to react under measured or modeled atmospheric conditions of temperature and local species concentrations. If a reaction is interesting, is slow in the gas phase, and has a high thermodynamic tendency to react, it is a good candidate for a laboratory study to seek a heterogeneous catalyst, if the reaction is thermodynamically unfavorable, there is no catalyst that can cause the reaction to occur. If a reaction is thermodynamically favored to occur but also endothermic, it will tend to be slow at stratospheric temperatures. We find, as expected, that four heterogeneous reactions important in causing the Antarctic ''ozone hole'' have high thermodynamic tendencies to occur under atmospheric conditions, but one of these is only weakly thermodynamically allowed in some regions of the atmosphere. The reaction of SO2 and HNO3 to form HONO has a high thermodynamic potential to occur, is a well-known laboratory reaction at ice temperature, and may occur in nitric acid-rich sulfate aerosols. Throughout the troposphere and stratosphere, we find that formaldehyde has an extremely high thermodynamic potential to reduce nitric acid. Formaldehyde is known to stick to and remain in sulfuric acid solution, where it adds water to form H2C(OH)(2). Near room-temperature H2C(OH)(2) reacts with nitric acid in a two-step mechanism to form two molecules of HONO, but the rate of this process under conditions of stratospheric sulfuric acid aerosols is unknown.

Fairbrother, D.H.; Sullivan, D.S.D.; Johnston, H.S.

1997-07-03T23:59:59.000Z

195

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)

196

Studies of Immobilized Homogeneous Metal Catalysts on Silica Supports  

SciTech Connect

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

Keith James Stanger

2003-05-31T23:59:59.000Z

197

From the Heterogeneity Jungle to Systematic Benchmarking  

Science Journals Connector (OSTI)

One of the key challenges in the development of model transformations is the resolution of recurring semantic and syntactic heterogeneities. Thus, we provide a systematic classification of heterogeneities buil...

M. Wimmer; G. Kappel; A. Kusel; W. Retschitzegger…

2011-01-01T23:59:59.000Z

198

Chapter 13 - Heterogeneous Catalysts and Biomass Conversion  

Science Journals Connector (OSTI)

Abstract The application of heterogeneous catalysts to conversion processes based on biomasses is described and discussed. The role of heterogeneous catalysts in the development of renewable industrial chemistry is emphasized.

Guido Busca

2014-01-01T23:59:59.000Z

199

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

SciTech Connect

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

Somorjai, Gabor A.; Park, Jeong Y.

2008-03-06T23:59:59.000Z

200

Organusulfur Catalysis With Reduced Molybdenum Sulfides Containing the Mo6S8 Cluster  

SciTech Connect

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

Thomas Jay Paskach

2002-08-27T23:59:59.000Z

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

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

202

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

SciTech Connect

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

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

2014-04-14T23:59:59.000Z

203

Evaluating the importance of innovative heterogeneous chemistry to explain observed stratospheric ozone depletion  

SciTech Connect

Currently, there is a widespread search for additional heterogeneous reactions or combination of heterogeneous and homogeneous (gas-phase) reactions that could catalytically reduce ozone to observed levels. In 1992, Burley and Johnston proposed that nitrosyl sulfuric acid (NSA) NOHSO{sub 4}, is a promising heterogeneous reactant for activating HCl in sulfuric acid particles. They list several sources for producing it in the stratosphere and they carried out thermodynamic and chemical kinetic calculations at one stratospheric altitude and at one latitude. NSA has been overlooked in all previous stratospheric model calculations, even though it has been observed in stratospheric sulfate aerosols. This study makes large scale atmospheric model calculations to test the proposal by Burley and Johnston that a promising heterogeneous process for activating HCl in sulfuric acid particles is a catalytic coupled based on nitrosyl sulfuric acid (NSA). This mechanism is examined under non-volcanic and volcanic conditions representative of the recent eruption of Mt. Pinatubo. The calculations set firm limits on the range of kinetic parameters over which this heterogeneous processes would be important in the global ozone balance, and thus is a guide for where laboratory work is needed. In addition, they have derived a preliminary time-dependent integration (1980--1994) to represent the observed trend in ozone. Comparison between model-derived and the observed ozone trend will be compared.

Kinnison, D.E.; Connell, P.S. [Lawrence Livermore National Lab., CA (United States). Atmospheric Science Div.

1996-02-27T23:59:59.000Z

204

Ion beam analyses of radionuclide migration in heterogeneous rocks  

Science Journals Connector (OSTI)

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

Valentino Rigato

2013-01-01T23:59:59.000Z

205

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

206

Anionic co-contaminants and the biogeochemical evolution of aquifer heterogeneity. Final technical report  

SciTech Connect

Adsorption heterogeneity of subsoils may depend on the sorbate and its concentration. Ligands in natural and contaminated subsoils may dissolve substantial metal oxides thereby altering the subsoil heterogeneity. We investigated these hypotheses on sands artificially and naturally coated with various amounts of metal oxides. The adsorbates Cu, oxalate, and mixtures of Cu and oxalate (Cu-Oxalate) were used as probes of the surface. For the concentration range studied, Binding Strength Analysis revealed that the naturally coated samples were heterogeneous at the microscale and the macroscale when oxalate was used as the probe of the surface. Cu revealed a smaller heterogeneity while Cu-Oxalate indicated an intermediate heterogeneity. Various elaborations of homogeneous-site Surface Complexation Models (SCM), calibrated to the surface protonation properties of goethite, modeled accurately the edges of oxalate, Cu, and mixtures of Cu and oxalate. The poorer fits for large concentrations was probably because of the site heterogeneity. The accuracy of SCMs was insensitive to the choice of surface protonation constants (pK{sub a}) and moderately sensitive to the choice of site density. The effective surface complexation constants (K{sup eff}) obtained from individual edges were somewhat different because of the concentration dependent heterogeneity. It was not always possible to use K{sup eff} values for one sorbate concentration to reproduce adsorption of other concentrations of the same sorbate. A modified version of the discrete pK{sub a} spectrum model closely reproduced the acid-base titration curve with two adsorption sites (four pK{sub a}`s). The adsorption of all concentrations of Cu, oxalate, and Cu-Oxalate was often reproduced with only one of those sites. The competition between the dissolved Al and the surface for the oxalate in solution was accurately reproduced with both sites. The dissolution of the oxide coating was often influenced by the pore velocity.

Fish, W.

1997-07-01T23:59:59.000Z

207

New Strategies for Organic Catalysis: The First Enantioselective Organocatalytic 1,3-Dipolar  

E-Print Network (OSTI)

Versity of California Berkeley, California 94720 DiVision of Chemistry and Chemical Engineering California Institute of broadly useful new strategies for enantioselective catalysis that utilize organic chemicals as reaction platform for the develop- ment of enantioselective organocatalytic Diels-Alder reactions (eq 2

MacMillan, David W. C.

208

Catalysis by dihydrofolate reductase and other enzymes arises from electrostatic preorganization,  

E-Print Network (OSTI)

Catalysis by dihydrofolate reductase and other enzymes arises from electrostatic preorganization dynamical effects. We then generate the catalytic land- scape of the enzyme and demonstrate that motions catalytic power of enzymes has been attempted to be rationalized by several proposals. Here, we would like

Barton, Paul I.

209

Structural model of F1–ATPase and the implications for rotary catalysis  

Science Journals Connector (OSTI)

...and R. M. Simmons Structural model of F1-ATPase and the implications for rotary...crystal structure of bovine mitochondrial F1-ATPase is described. Several features...approximately spherical alpha3beta3 sub-assembly. F1-ATPase|crystal structure|rotary catalysis...

2000-01-01T23:59:59.000Z

210

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

E-Print Network (OSTI)

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

Senkan, Selim M.

211

Pacific Northwest National Laboratory: INstItute for INterfacIaL cataLysIs  

E-Print Network (OSTI)

-pressure hydrogen may be the fuel/energy carrier in the long term, strategies to help supply and maintain the nation and diesel. the Institute for Interfacial catalysis is supporting PNNL's energy conversion Initiative conversion of coal to liquid transportation fuels. IndIReCt LIqueFaCtIon: MoRe VaLuabLe PRoduCts FoR Less

212

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

E-Print Network (OSTI)

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

Bell, Alexis T.

213

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

E-Print Network (OSTI)

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

Iglesia, Enrique

214

Applied Catalysis A: General 226 (2002) 183192 NO reduction by urea under lean conditions  

E-Print Network (OSTI)

-734-763-0459. E-mail address: gulari@engin.umich.edu (E. Gulari). burn gasoline or a diesel engine. Early studiesApplied Catalysis A: General 226 (2002) 183­192 NO reduction by urea under lean conditions over, Jiraporn Leeratc, Somchai Osuwanc a Chemical Engineering Department, University of Michigan, Ann Arbor, MI

Gulari, Erdogan

215

ANL/ALCF/ESP-13/2 Materials Design and Discovery: Catalysis and  

E-Print Network (OSTI)

electronic) degrees of freedom are relevant, the methods of choice in the surface science, condensed matter) project was to perform fast-accurate DFT calculations on materials for energy and catalysis using the GPAW[1, 2, 3] code on Blue Gene/Q. The types of calculations included significantly reduced time

Kemner, Ken

216

Probing the chemistry of thioredoxin catalysis Arun P. Wiita1,2  

E-Print Network (OSTI)

organisms1 . Although catalysis is thought to proceed through a substitution nucleophilic bimolecular (SN2) reaction1,2 , the role of the enzyme in modulating this chemical reaction is unknown. Here, using single of the catalytic reaction, the first requiring a reorientation of the substrate disulphide bond, causing a short

Fernandez, Julio M.

217

Diversity of chemical mechanisms in thioredoxin catalysis revealed by single-molecule force spectroscopy  

E-Print Network (OSTI)

-origin Trxs show both nucleophilic substitution (SN2) and SET reactions. A computational analysis of Trx-origin Trxs reduce disulfide bonds through a single-electron transfer reaction (SET), whereas bacterial of Trx catalysis. Enzymes are exceptional catalysts that can accelerate reaction rates by several orders

Berne, Bruce J.

218

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

SciTech Connect

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

219

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

220

Modelling long-distance seed dispersal in heterogeneous landscapes.  

SciTech Connect

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

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

2008-01-01T23:59:59.000Z

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

Spatial homogenization for plate-type critical assemblies. [LMFBR  

SciTech Connect

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

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

1983-01-01T23:59:59.000Z

222

Tensor Rank and Stochastic Entanglement Catalysis for Multipartite Pure States  

E-Print Network (OSTI)

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

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

2010-11-10T23:59:59.000Z

223

DEFLECTION OF A HETEROGENEOUS WIDE-BEAM UNDER UNIFORM PRESSURE LOAD  

SciTech Connect

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

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

2014-07-01T23:59:59.000Z

224

Heterogeneous Systems Testing Techniques: An Exploratory Survey.  

E-Print Network (OSTI)

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

Ghazi, Ahmad; Petersen, Kai

2015-01-01T23:59:59.000Z

225

Fractal Networks Explain Regional Myocardial Flow Heterogeneity  

Science Journals Connector (OSTI)

Regional myocardial blood flow is very heterogeneous. This has been found by injection of radioactively labeled microspheres, or the “molecular microsphere” iododesmethylimipramine, and measuring the depositio...

Johannes H. G. M. van Beek; James B. Bassingthwaighte…

1989-01-01T23:59:59.000Z

226

A study of the homogenization of soils  

SciTech Connect

In accordance with US Environmental Protection Agency (US EPA) regulations, areas of land that have been contaminated must be returned to an environmental condition that permits less restrictive forms of use. In anticipation of being listed as an EPA Superfund Site, the United States Department of Energy`s (US DOE) Nevada Test Site (NTS) is evaluating existing the technologies, and supporting the development of new technologies, for the removal of plutonium contaminants from soils. During the 1950s, DOE conducted a series of tests on the NTS wherein attempts were made to detonate nuclear weapons by igniting charges of high explosives packed around the weapons` warheads. While the warheads never achieved criticality, each test disseminated particulate plutonium over several square miles, principally in Area 11 of the NTS.DOE`s Nevada Operations Office has committed to a Plutonium In Soils Integrated Demonstration Project (PuID) to evaluate existing and developmental technologies for the safe removal of plutonium contamination from soils. It is DOE`s intention to provide approximately one ton of Area 11 soil, traced with a non-radioactive plutonium surrogate, to each of several companies with expertise in the removal of soil contaminants. These companies have expressed an interest in contracting with DOE for remediation of NTS soils. DOE wishes to evaluate each company`s process in an unbiased and statistically justifiable manner. For this reason, DOE must provide to each company a large sample of soil for prototype testing. The soil must be homogenized such that the representativeness of each split is well documented and defensible. The process of uniformly mixing large volumes of soil has not been addressed, to our knowledge, in the hydrogeologic, soil science or mining literature. Several mixing devices are currently being evaluated by DOE for use in the PuID. This report describes the results of some initial experimentation with a small cement mixer.

Giovine, L.R.S.; Miller, F.L. Jr.

1993-06-01T23:59:59.000Z

227

Synthesis and Optimization of Reversible Circuits for Homogeneous Boolean Functions  

E-Print Network (OSTI)

Homogenous Boolean function is an essential part of any cryptographic system. The ability to construct an optimized reversible circuits for homogeneous Boolean functions might arise the possibility of building cryptographic system on novel computing paradigms such as quantum computers. This paper shows a factorization algorithm to synthesize such circuits.

Ahmed Younes

2007-10-02T23:59:59.000Z

228

DIRECT NUMERICAL SIMULATION OF INTERACTION OF DETONATION WAVE WITH HOMOGENEOUS  

E-Print Network (OSTI)

DIRECT NUMERICAL SIMULATION OF INTERACTION OF DETONATION WAVE WITH HOMOGENEOUS ISOTROPIC TURBULENCE SIMULATION OF INTERACTION OF DETONATION WAVE WITH HOMOGENEOUS ISOTROPIC TURBULENCE HARI NARAYANAN NAGARAJAN The propagation of a shock or detonation wave through a reactive mixture has been the subject of research for over

Texas at Arlington, University of

229

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.

Anderson Hall

2009-03-31T23:59:59.000Z

230

Task and Machine Heterogeneities: Higher Moments Matter  

E-Print Network (OSTI)

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

Maciejewski, Anthony A.

231

Abstract 2043: Modeling the differential responses of cancer stem cells (CSCs) as heterogeneous versus homogenous populations in human cancers  

Science Journals Connector (OSTI)

...Biomodels, LLC, Watertown, MA. Emerging data suggests that many human cancers including breast, brain, lung, colon, pancreatic and head and neck cancer are maintained by a subpopulation of self-renewing cells characterized as cancer stem...

Maria L. Mancini

2014-10-01T23:59:59.000Z

232

Structural and Energetic Heterogeneity in Protein Folding  

E-Print Network (OSTI)

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

Steven S. Plotkin; Jose N. Onuchic

2000-09-27T23:59:59.000Z

233

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

234

Hydrogen storage materials and method of making by dry homogenation  

DOE Patents (OSTI)

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

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

2002-01-01T23:59:59.000Z

235

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

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

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

236

Impact of catalysis on the production of the top 50 US commodity chemicals  

SciTech Connect

Information on each chemical is stored in an accompanying Excel{trademark} 4.0 spreadsheet (``top5Ochem.xcl``). This analysis tool allows the user to make assumptions about process yield improvements and evaluate the corresponding impact on the process and feedstock energy. Many scenarios have been investigated and are reported in the text. If all of the catalytic processes associated with the top 50 chemicals were raised to their maximum process yields, the corresponding process and feedstock energy savings would exceed 0.47 quads per year. More realistic process yield improvements of 1%, 5%, and 10% where possible, would save 0.03, 0.14, and 0.23 quads per year. Many of the commodity chemicals face limitations from both the current catalyst and process. Catalysis is vital, but catalysis alone is not the answer to maximizing energy savings. Integration of catalysis development with process engineering research can lead to significant energy savings during the production of the top 50 chemicals.

Tonkovich, A.L.Y.

1994-03-01T23:59:59.000Z

237

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

SciTech Connect

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

James F. Haw

2008-06-28T23:59:59.000Z

238

One-Directional Perfect Cloak Created With Homogeneous Material  

E-Print Network (OSTI)

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

Xi, Sheng

239

Molecular Dynamics Simulation of Homogeneous Crystal Nucleation in Polyethylene  

E-Print Network (OSTI)

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

Yi, Peng

240

Impurities in a Homogeneous Electron Gas Jung-Hwan Song  

E-Print Network (OSTI)

Electron Gas Abstract approved: Henri J. F. Jansen Immersion energies for an impurity in a homogeneous. Jansen, who has been a most important contributor to this thesis, and gave me guidelines and helps

Jansen, Henri J. F.

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

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

242

HYPERSONIC BUCKSHOT: ASTROPHYSICAL JETS AS HETEROGENEOUS COLLIMATED PLASMOIDS  

SciTech Connect

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

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

2009-04-20T23:59:59.000Z

243

Hypersonic Buckshot: Astrophysical Jets as Heterogeneous Collimated Plasmoids  

E-Print Network (OSTI)

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

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

2008-05-30T23:59:59.000Z

244

Phase-Transfer Catalysis: Chiral Phase-Transfer-Catalyzed Formation of Carbon-Carbon Bonds  

Science Journals Connector (OSTI)

It is only within the last two decades that heterogeneous enantioselective syntheses involving chiral phase-transfer catalysts (quaternary ammonium and phosphonium salts, macrocyclic miltidentate ligands, poly...

Charles M. Starks; Charles L. Liotta; Marc E. Halpern

1994-01-01T23:59:59.000Z

245

Heterogeneous Recycling in Fast Reactors  

SciTech Connect

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

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

2012-07-30T23:59:59.000Z

246

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

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

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

247

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

SciTech Connect

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

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

1989-05-01T23:59:59.000Z

248

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

249

Existence of homogeneous vectors on the fiber space of the tangent bundle  

Science Journals Connector (OSTI)

Let M = G/K be a homogeneous differentiable manifold. We consider the homogeneous bundle $$ \\Im $$ = (G, ?, G/K, K) ...

R. Chavosh Khatamy; M. Toomanian

2007-09-01T23:59:59.000Z

250

Regularity lifting of weak solutions for nonlinear sub-Laplace equations on homogeneous groups  

Science Journals Connector (OSTI)

Let G be a homogeneous group, and let X 1, X 2, … , X m be left invariant real vector fields being homogeneous of degree one on

Xiaojing Feng; Pengcheng Niu

2012-04-01T23:59:59.000Z

251

Catalysis and activation of magic states in fault-tolerant architectures  

SciTech Connect

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

252

Chromomagnetic catalysis of color superconductivity in a (2+1)-dimensional Nambu–Jona-Lasinio model  

Science Journals Connector (OSTI)

We investigate the influence of a constant uniform external chromomagnetic field H on the formation of color superconductivity. The consideration is made in the framework of a (2+1)-dimensional Nambu–Jona-Lasinio model with two different four-fermionic structures responsible for ?q¯q? and diquark ?qq? condensates. In particular, it is shown that there exists a critical value Hc of the external chromomagnetic field such that at H>Hc a nonvanishing diquark condensate is dynamically created (the so-called chromomagnetic catalysis effect of color superconductivity). Moreover, external chromomagnetic fields may in some cases enhance the diquark condensate of color superconductivity.

D. Ebert, K. G. Klimenko, and H. Toki

2001-06-13T23:59:59.000Z

253

On the Mechanical Interaction of Light With Homogeneous Liquids  

E-Print Network (OSTI)

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

de Reus, Michiel

2013-01-01T23:59:59.000Z

254

Development of homogeneous mobile robots for box-pushing problem  

Science Journals Connector (OSTI)

This paper describes the development of a pair of homogeneous mobile robot using AT89C51 microcontroller with two 6V DC motors to address the box-pushing problem. In this work, two homogeneous mobile robots have been fully developed exclusively to address the box-pushing application that is described as ''Pushing a box-like solid item to reach the goal position already defined by more than one mobile robot through the cooperation among them''. Teaching the mobile robots using reinforcement learning is easier, because of specifying a reward function for every task completed by them.

C. Paramasivam; T. Sornakumar

2009-01-01T23:59:59.000Z

255

Orthogonality of Homogeneous geodesics on the tangent bundle  

E-Print Network (OSTI)

Let $\\xi=(G\\times_{K} \\mathcal{G} / \\mathcal{K}, \\rho_{\\xi}, \\emph{G} / \\emph{K},\\mathcal{G} / \\mathcal{K})$ be the associated bundle and $\\tau_{G/K}=(T_{G/K},\\pi_{G/K},G/K, \\textrm{R}^{m})$ be the tangent bundle of special examples of odd dimension solvable Lie groups equipped with left invariant Riemannian metric. In this paper we prove some conditions about the existence of homogeneous geodesic on the base space of $\\tau_{G/K}$ and homogeneous (geodesic) vectors on the fiber space of $\\xi$ .

Khatamy, R Chavosh

2011-01-01T23:59:59.000Z

256

Effect of Spatial Heterogeneity on Near-Limit Propagation of a Stable Detonation  

E-Print Network (OSTI)

The effect of introducing a spatial heterogeneity into an explosive medium is studied computationally by examining the detonation velocity near the limit to propagation in a thin explosive layer. The explosive system studied is an ideal gas with a single exothermic reaction governed by a pressure-dependent reaction rate ($p^n$) with a pressure exponent of $n = 3$. A pressure-dependent reaction rate, rather than the exponential dependence of reaction on temperature of Arrhenius kinetics, is used so that the detonation wave is stable in the homogeneous case and can be modelled with simple, analytical techniques, and thus the effect of introducing heterogeneity can be clearly identified. The two-dimensional slab of explosive is bounded by a layer of inert gas with the same thermodynamic properties as the explosive. The heterogeneity is introduced into the explosive via a large-amplitude, two-dimensional sinusoidal ripple in density in the initialization of the simulation, while maintaining a constant pressure. T...

Li, Jianling; Higgins, Andrew J

2014-01-01T23:59:59.000Z

257

Single molecule tracking of heterogeneous diffusion  

Science Journals Connector (OSTI)

The mean square displacement of heterogeneous diffusion obeys the Einstein relation, thereby showing no sign of heterogeneities in the ensemble measurement of the diffusion constant. The signature of spatial heterogeneities appears in the time evolution of the non-Gaussian distribution and in the cross correlation between the square displacements at different times, both available from single molecule diffusional trajectories. As a quantitative measure, the non-Gaussian indicator g(t) decays asymptotically to zero according to 1/t for finite time correlation, but saturates at a plateau value for power-law correlation. In addition, the joint moment correlation function f(t,?) provides a direct probe of the memory effect of the fluctuating rate constant. A two-state diffusion model and a stochastic Gaussian model are constructed to evaluate these quantities and are shown to yield the same result within the second cumulant expansion.

Jianshu Cao

2001-03-16T23:59:59.000Z

258

MESOSCALE MODELLING OF WIND ENERGY OVER NON-HOMOGENEOUS TERRAIN  

E-Print Network (OSTI)

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

Pielke, Roger A.

259

Framework for Statistical Analysis of Homogeneous Multicore Power Grid Networks  

E-Print Network (OSTI)

Framework for Statistical Analysis of Homogeneous Multicore Power Grid Networks Guanglei Liu the feasibility of such a framework. 1 Index Terms ­ Multicore, Power Grid Network, Statistical Analysis, Process voltage. It has become the number one concern in the design of multicore power grid network. Due

Fan, Jeffrey

260

A CHARACTERIZATION OF HOMOGENEOUS SPACES WITH POSITIVE HYPERBOLIC RANK  

E-Print Network (OSTI)

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

Connell, Christopher

Note: This page contains sample records for the topic "homogeneous catalysis heterogeneous" from the National Library of EnergyBeta (NLEBeta).
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261

Remarks on an homogeneous model of ocean circulation.  

E-Print Network (OSTI)

Remarks on an homogeneous model of ocean circulation. T. Colin CEA, Centre d'´etudes de Limeil-Valenton, 94195 Villeneuve Saint-Georges Cedex, France. Abstract : We consider a simplified model of ocean relation. This singular limit implies the existence of boundary layers that correspond to currents

Colin, Thierry

262

Hopf Bifurcation and Oscillations in Homogeneous Communication Networks  

E-Print Network (OSTI)

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

Alpcan, Tansu

263

Homogeneous bubble nucleation in rhyolitic melt: Experiments and nonclassical theory  

E-Print Network (OSTI)

Homogeneous bubble nucleation in rhyolitic melt: Experiments and nonclassical theory H. M eruptions. The first and most critical step in degassing is the nucleation of gas bubbles, which requires inferred from bubble nucleation experiments in silicate melts are, however, lower than direct macroscopic

Gonnermann, Helge

264

HOMOGENEOUS MODELS IN GENERAL RELATIVITY AND GAS DYNAMICS  

E-Print Network (OSTI)

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

Novikov, Sergei Petrovich

265

Modeling the Energy Efficiency of Heterogeneous Clusters  

E-Print Network (OSTI)

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

Teo, Yong-Meng

266

Transport Control Protocol (TCP) In Heterogeneous Networks  

E-Print Network (OSTI)

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

Shihada, Basem

267

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

268

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

E-Print Network (OSTI)

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

MacMillan, David W. C.

269

Chemoselective SN2? reaction of nitroalkanes to dialkyl 2-(bromomethyl)fumarates under cetyltrimethylammonium hydroxide (CTAOH) catalysis  

Science Journals Connector (OSTI)

The chemoselective SN2? reaction of a variety of primary nitroalkanes to dialkyl 2-(bromomethyl)fumarates can be efficiently performed under cetyltrimethylammonium hydroxide (CTAOH) catalysis. The ?,?-unsaturated esters were obtained in satisfactory to good yields with the complete retention of the nitro group.

Roberto Ballini; Serena Gabrielli; Alessandro Palmieri

2010-01-01T23:59:59.000Z

270

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

271

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

SciTech Connect

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

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

2014-02-04T23:59:59.000Z

272

Modeling Heterogeneity in Indirect Effects: Multilevel Structural Equation Modeling Strategies  

E-Print Network (OSTI)

The heterogeneity implicit in much of social science research can be accommodated by using complex modeling procedures such as SEM or MLM. Ignoring heterogeneity, particularly with regard to nested data structures, can have serious consequences...

Fall, Emily C.

2011-12-31T23:59:59.000Z

273

Homogeneous nucleation rate measurements in supersaturated water vapor  

Science Journals Connector (OSTI)

The rate of homogeneous nucleation in supersaturated vapors of water was studied experimentally using a thermal diffusion cloud chamber. Helium was used as a carrier gas. Our study covers a range of nucleation rates from 3 × 10 ? 1 to 3 × 10 2 cm ? 3 s ? 1 at four isotherms: 290 300 310 and 320 K . The molecular content of critical clusters was estimated from the slopes of experimental data. The measured isothermal dependencies of nucleation rate of water on saturation ratio were compared with the prediction of the classical theory of homogeneous nucleation the empirical prediction of Wölk et al. [J. Chem. Phys.117 10 (2002)] the scaled model of Hale [Phys. Rev. A33 4156 (1986)] and the former nucleation onset data.

David Brus; Vladimír Ždímal; Ji?í Smolík

2008-01-01T23:59:59.000Z

274

WSN-inspired Sleep Protocols for Heterogeneous LTE Networks  

E-Print Network (OSTI)

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

Paris-Sud XI, Université de

275

High load operation in a homogeneous charge compression ignition engine  

DOE Patents (OSTI)

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

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

2008-12-23T23:59:59.000Z

276

Invariant Properties of Straight Homogeneous Generalized Cylinders and Their Contours  

Science Journals Connector (OSTI)

A fundamental group in computer vision is the recovery of three-dimensional shape from image data. While this problem is in general underconstrained, the authors show that it can be simplified in the case where the objects being viewed are generalized ... Keywords: 3D shape recovery, Gaussian curvature, computer vision, computerised pattern recognition, computerised picture processing, image contours, invariant property, segmentation, straight homogeneous generalized cylinders

J. Ponce; D. Chelberg; W. B. Mann

1989-09-01T23:59:59.000Z

277

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

SciTech Connect

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

278

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

279

States with identical steady dissipation rate: Role of kinetic constants in enzyme catalysis  

E-Print Network (OSTI)

A non-equilibrium steady state is characterized by a non-zero steady dissipation rate. Chemical reaction systems under suitable conditions may generate such states. We propose here a method that is able to distinguish states with identical values of the steady dissipation rate. This necessitates a study of the variation of the entropy production rate with the experimentally observable reaction rate in regions close to the steady states. As an exactly-solvable test case, we choose the problem of enzyme catalysis. Link of the total entropy production with the enzyme efficiency is also established, offering a desirable connection with the inherent irreversibility of the process. The chief outcomes are finally noted in a more general reaction network with numerical demonstrations.

Banerjee, Kinshuk

2014-01-01T23:59:59.000Z

280

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

E-Print Network (OSTI)

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

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

2007-01-01T23:59:59.000Z

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


281

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

SciTech Connect

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

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

2013-09-17T23:59:59.000Z

282

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

283

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

SciTech Connect

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

Mark A. Barteau

2009-09-15T23:59:59.000Z

284

1. Introduction Copper, along with iron active sites dominate the field of  

E-Print Network (OSTI)

#12;1. Introduction Copper, along with iron active sites dominate the field of biological oxygen chemistry[1] and play important roles in homogeneous[2] and heterogeneous catalysis.[3, 4] Copper pro- teins heme ± iron centers).[8] The known copper proteins which are involved in dioxygen binding, activation

Chen, Peng

285

Steady- and transient-state analyses of fully ceramic microencapsulated fuel loaded reactor core via two-temperature homogenized thermal-conductivity model  

Science Journals Connector (OSTI)

Abstract Fully ceramic microencapsulated (FCM) fuel, a type of accident-tolerant fuel (ATF), consists of TRISO particles randomly dispersed in a SiC matrix. In this study, for a thermal analysis of the FCM fuel with such a high heterogeneity, a two-temperature homogenized thermal-conductivity model was applied by the authors. This model provides separate temperatures for the fuel-kernels and the SiC matrix. It also provides more realistic temperature profiles than those of harmonic- and volumetric-average thermal conductivity models, which are used for thermal analysis of a fuel element in \\{VHTRs\\} having a composition similar to the FCM fuel, because such models are unable to provide the fuel-kernel and graphite matrix temperatures separately. In this study, coupled with a neutron diffusion model, a FCM fuel-loaded reactor core is analyzed via a two-temperature homogenized thermal-conductivity model at steady- and transient-states. The results are compared to those from harmonic- and volumetric-average thermal conductivity models, i.e., we compare keff eigenvalues, power distributions, and temperature profiles in the hottest single-channel at steady-state. At transient-state, we compare total powers, reactivity, and maximum temperatures in the hottest single-channel obtained by the different thermal analysis models. The different thermal analysis models and the availability of fuel-kernel temperatures in the two-temperature homogenized thermal-conductivity model for Doppler temperature feedback cause significant differences as revealed by comparisons.

Yoonhee Lee; Nam Zin Cho

2015-01-01T23:59:59.000Z

286

Lattice Boltzmann simulations of decaying homogeneous isotropic turbulence  

Science Journals Connector (OSTI)

Decaying homogeneous isotropic turbulence in inertial and rotating reference frames is investigated to evaluate the capability of the lattice Boltzmann method in turbulence. In the inertial frame case, the decay exponents of kinetic energy and dissipation and the low wave-number scaling of the spectrum are studied. The results are in agreement with classical ones. In the frame-rotation case, simulations show that the energy decay rate decreases with decreasing Rossby number as the energy cascade is inhibited by rotation, again in agreement with turbulence physics. These results clearly indicate that the lattice Boltzmann method captures important features of decaying turbulence.

Huidan Yu; Sharath S. Girimaji; Li-Shi Luo

2005-01-25T23:59:59.000Z

287

Homogeneous Charge Compression Ignition Free Piston Linear Alternator  

SciTech Connect

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

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

1998-11-01T23:59:59.000Z

288

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

289

Lack of energy equipartition in homogeneous heated binary granular mixtures  

E-Print Network (OSTI)

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

A. Barrat; E. Trizac

2002-05-21T23:59:59.000Z

290

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

291

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

292

Heterogeneously integrated microsystem-on-a-chip  

DOE Patents (OSTI)

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

Chanchani, Rajen (Albuquerque, NM)

2008-02-26T23:59:59.000Z

293

Critical Endpoint and Inverse Magnetic Catalysis for Finite Temperature and Density Quark Matter in a Magnetic Background  

E-Print Network (OSTI)

In this article we study chiral symmetry breaking for quark matter in a magnetic background, $\\bm B$, at finite temperature and quark chemical potential, $\\mu$, making use of the Ginzburg-Landau effective action formalism. As a microscopic model to compute the effective action we use the renormalized quark-meson model. Our main goal is to study the evolution of the critical endpoint, ${\\cal CP}$, as a function of the magnetic field strength, and investigate on the realization of inverse magnetic catalysis at finite chemical potential. We find that the phase transition at zero chemical potential is always of the second order; for small and intermediate values of $\\bm B$, ${\\cal CP}$ moves towards small $\\mu$, while for larger $\\bm B$ it moves towards moderately larger values of $\\mu$. Our results are in agreement with the inverse magnetic catalysis scenario at finite chemical potential and not too large values of the magnetic field, while at larger $\\bm B$ direct magnetic catalysis sets in.

M. Ruggieri; L. Oliva; P. Castorina; R. Gatto; V. Greco

2014-02-04T23:59:59.000Z

294

Effect of high pressure homogenization on the physical properties of milk  

E-Print Network (OSTI)

homogenization in milk with 3'to milk fat homogenized at 79. 5'C, . 14. Effect of homogenization pressure on fat globule size distribution using double stage homogenization in milk with 3' milk fat homogenized at 79. 5'C. . . . . 52 . . . . 54 . . . . 55... to protein mass ratio (FPM) increased, particularly when FPM & 6. Surface to volume 13 mean diameter increased from 0. 42+ . 02 p. m at FPM of 1, to 1. 85 + . 09 at FPM of 13. Increasing FPM by varying the fat content led to an increase in the specific...

Gonzalez De Cossio, Carlos

2012-06-07T23:59:59.000Z

295

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

296

The Effect of Surface Heterogeneity on Cloud Absorption Estimates  

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

Effect of Surface Heterogeneity on Cloud Absorption Estimates W. J. Wiscombe and A. Marshak National Aeronautics and Space Administration - Goddard Space Flight Center Climate and...

297

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

Office of Scientific and Technical Information (OSTI)

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

298

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

Open Energy Info (EERE)

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

299

Testing gaussianity, homogeneity and isotropy with the cosmic microwave background  

E-Print Network (OSTI)

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

L. Raul Abramo; Thiago S. Pereira

2010-05-13T23:59:59.000Z

300

Homogeneous gas-phase nucleation in silane pyrolysis  

Science Journals Connector (OSTI)

Dilute and particle free mixtures of silane in the range of 100 ppm to 10% by volume in different carrier gases were decomposed thermally in a tube reactor. The onset of homogeneous nucleation was determined as a function of temperature and silane concentration for each carrier gas using a CNC with a detection limit of ca 0.01 ?m. The gaseous decomposition by-products, disilane, trisilane and hydrogen were measured simultaneously using gas-phase chromatography. The onset of gas-phase nucleation was found to be inversely proportional to the temperature and influenced by the nature of the carrier gas. In inert gases, no chemical reaction took place between the decomposition products of silane and the carrier gas. In hydrogen, equilibrium displacement with the primary decomposition product (SiH2) lead to a retardation of particle formation. Thus, the temperatures of onset of gas-phase nucleation was higher for mixtures in hydrogen than for mixtures in inert gases.

Frank Slootman; Jean-Claude Parent

1994-01-01T23:59:59.000Z

Note: This page contains sample records for the topic "homogeneous catalysis heterogeneous" from the National Library of EnergyBeta (NLEBeta).
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We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


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

Experimental Evaluation on Modulus of Equivalent Homogeneous Ettringite  

Science Journals Connector (OSTI)

In the present study, the average modulus of delayed ettringite is evaluated by an experimental method combined with theoretical analysis. Firstly, the delayed ettringite crystal is synthesized by chemical reaction of Aluminum sulfate and calcium hydroxide. Secondly, specimens are obtained by compressing the delayed ettringite crystal under different pre-loads. Thirdly, the variation of the modulus of the specimen with different pre-loads is tested using Instron material test machine and the SHPB technique, respectively. It is found that the experimental data may be suitably fitted by Boltzmann Function. Finally, the porosity of the specimen is detected using the saturation method, and the effect of the porosity on the modulus is analyzed by the Eshelby's equivalent inclusion method and the Mori-Tanaka's scheme. The static and dynamic modulli of the equivalent homogeneous ettringite obtained in present study are approximately 10.64 \\{GPa\\} and 24.61 GPa, respectively.

Minghua Zhang; Jiankang Chen; Jue Zhu; Jiangying Chen

2009-01-01T23:59:59.000Z

303

Generalized quantum gravity condensates for homogeneous geometries and cosmology  

E-Print Network (OSTI)

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

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

2015-01-05T23:59:59.000Z

304

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.

305

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

SciTech Connect

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

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

1993-07-01T23:59:59.000Z

306

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

SciTech Connect

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

Saladino, Alexander C.; Larsen, Sarah C.

2005-07-15T23:59:59.000Z

307

Dynamics on modular networks with heterogeneous correlations  

SciTech Connect

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

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

2014-06-15T23:59:59.000Z

308

Renewable electricity policies, heterogeneity, and cost effectiveness  

Science Journals Connector (OSTI)

Abstract Renewable electricity policies promote investment in renewable electricity generators and have become increasingly common around the world. Because of intermittency and the composition of other generators in the power system, the value of certain renewable – particularly wind and solar – varies across locations and technologies. This paper investigates the implications of this heterogeneity for the cost effectiveness of renewable electricity policies. A simple model of the power system shows that renewable electricity policies cause different investment mixes. Policies also differ according to their effect on electricity prices, and both factors cause the cost effectiveness to vary across policies. We use a detailed, long-run planning model that accounts for intermittency on an hourly basis to compare the cost effectiveness for a range of policies and alternative parameter assumptions. The differences in cost effectiveness are economically significant, where broader policies, such as an emissions price, outperform renewable electricity policies.

Harrison Fell; Joshua Linn

2013-01-01T23:59:59.000Z

309

Hetero-/homogeneous combustion of syngas mixtures over platinum at fuel-rich stoichiometries and pressures up to 14 bar  

Science Journals Connector (OSTI)

Abstract The catalytic and gas-phase combustion of H2/CO/O2/N2 mixtures was investigated in a platinum-coated channel-flow reactor at fuel-rich equivalence ratios 2–7, H2:CO volumetric ratios 1:2 to 5:1, pressures 1–14 bar, and wall temperatures 750–1250 K. In situ, 1-D Raman measurements of major gas-phase species concentrations over the catalyst boundary layer assessed the catalytic processes. Gas-phase combustion was monitored by planar laser-induced fluorescence (LIF) of the OH radical at pressures p ? 5 bar and of hot O2 at p > 5 bar, wherein OH-LIF was not applicable due to strong quenching. Simulations were performed with a 2-D elliptic code that included detailed heterogeneous and homogeneous chemical reaction mechanisms. The capacity of O2-LIF to assess the flame front positions at elevated pressures and fuel-rich stoichiometries has been demonstrated. The employed reaction schemes reproduced the measured H2, CO and O2 catalytic conversions as well as the flame positions and shapes over the entire investigated parameter range. Even though the catalytic conversion of the limiting O2 reactant was nearly transport-limited, the competition between H2 and CO for O2 consumption allowed for evaluation of the catalytic kinetics. Under rich stoichiometries, the oxidation of CO(s) via the HCOO(s) reaction pathway was significant. The sensitivity of gaseous combustion on catalytic reactions was strong, exemplifying the need of accurate surface chemistry when modeling syngas hetero-/homogeneous combustion. Adsorption of the H radical considerably inhibited gaseous combustion, especially at the lowest H2:CO ratios. The key surface reactions affecting gas-phase combustion were the same for all pressures. For a given stoichiometry, the sensitivity of homogeneous ignition on the inlet concentration of CO was modest, as the preferential catalytic oxidation of CO increased the H2:CO ratio over the gaseous induction zone.

Marco Schultze; John Mantzaras; Felix Grygier; Rolf Bombach

2014-01-01T23:59:59.000Z

310

Autonomous Demand Response in Heterogeneous Smart Grid Topologies  

E-Print Network (OSTI)

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

Mohsenian-Rad, Hamed

311

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

E-Print Network (OSTI)

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

Chawathe, Sudarshan S.

312

SHORT COMMUNICATION Flow rate-modified streaming effects in heterogeneous  

E-Print Network (OSTI)

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

Xuan, Xiangchun "Schwann"

313

Dose homogeneity specification for reference dosimetry of nonstandard fields  

SciTech Connect

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

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

2012-01-15T23:59:59.000Z

314

How memory generates heterogeneous dynamics in temporal networks  

E-Print Network (OSTI)

Empirical temporal networks display strong heterogeneities in their dynamics, which profoundly affect processes taking place on these networks, such as rumor and epidemic spreading. Despite the recent wealth of data on temporal networks, little work has been devoted to the understanding of how such heterogeneities can emerge from microscopic mechanisms at the level of nodes and links. Here we show that long-term memory effects are present in the creation and disappearance of links in empirical networks. We thus consider a simple generative modeling framework for temporal networks able to incorporate these memory mechanisms. This allows us to study separately the role of each of these mechanisms in the emergence of heterogeneous network dynamics. In particular, we show analytically and numerically how heterogeneous distributions of contact durations, of inter-contact durations and of numbers of contacts per link emerge. We also study the individual effect of heterogeneities on dynamical processes, such as the ...

Vestergaard, Christian L; Barrat, Alain

2014-01-01T23:59:59.000Z

315

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

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

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

316

Numerical homogenization of concrete microstructures without explicit meshes  

SciTech Connect

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

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

2011-12-15T23:59:59.000Z

317

Geodesic Particle Paths Inside a Nonrotating, Homogeneous, Spherical Body  

E-Print Network (OSTI)

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

Homer G. Ellis

2012-10-18T23:59:59.000Z

318

Modeling of homogeneous charge compression ignition (HCCI) of methane  

SciTech Connect

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

319

Condensation of cloud microdroplets in homogeneous isotropic turbulence  

E-Print Network (OSTI)

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

Alessandra S. Lanotte; Agnese Seminara; Federico Toschi

2008-07-15T23:59:59.000Z

320

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

E-Print Network (OSTI)

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

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

2014-01-01T23:59:59.000Z

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

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

322

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

E-Print Network (OSTI)

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

Andreae, Morgan M. (Morgan MacKenzie)

2006-01-01T23:59:59.000Z

323

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

324

Microstructure homogenization control of Nb-bearing X65 pipeline steel by the CSP process  

Science Journals Connector (OSTI)

In order to get the controlled methods of microstructure homogenization and high strengthening-toughening combination by compact strip production (CSP) rolling, the dynamic recrystallization characteristics of ea...

Ming-yang Li; Ya-zheng Liu; Tao Zhu…

2011-02-01T23:59:59.000Z

325

Approximation of inhomogeneous thermal lines via series connection of homogeneous thermal lines  

Science Journals Connector (OSTI)

A method is given for approximating an arbitrary inhomogeneous thermal line (ITL) as a series connection of homogeneous thermal lines (HTL). The method is compared with...

L. S. Eleinikova

1974-10-01T23:59:59.000Z

326

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

SciTech Connect

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

White, J. M.; Bercaw, J.

2002-05-16T23:59:59.000Z

327

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

328

Heterogeneous scalable framework for multiphase flows.  

SciTech Connect

Two categories of challenges confront the developer of computational spray models: those related to the computation and those related to the physics. Regarding the computation, the trend towards heterogeneous, multi- and many-core platforms will require considerable re-engineering of codes written for the current supercomputing platforms. Regarding the physics, accurate methods for transferring mass, momentum and energy from the dispersed phase onto the carrier fluid grid have so far eluded modelers. Significant challenges also lie at the intersection between these two categories. To be competitive, any physics model must be expressible in a parallel algorithm that performs well on evolving computer platforms. This work created an application based on a software architecture where the physics and software concerns are separated in a way that adds flexibility to both. The develop spray-tracking package includes an application programming interface (API) that abstracts away the platform-dependent parallelization concerns, enabling the scientific programmer to write serial code that the API resolves into parallel processes and threads of execution. The project also developed the infrastructure required to provide similar API's to other application. The API allow object-oriented Fortran applications direct interaction with Trilinos to support memory management of distributed objects in central processing units (CPU) and graphic processing units (GPU) nodes for applications using C++.

Morris, Karla Vanessa

2013-09-01T23:59:59.000Z

329

Adaptive heterogeneous multi-robot teams  

SciTech Connect

This research addresses the problem of achieving fault tolerant cooperation within small- to medium-sized teams of heterogeneous mobile robots. The author describes a novel behavior-based, fully distributed architecture, called ALLIANCE, that utilizes adaptive action selection to achieve fault tolerant cooperative control in robot missions involving loosely coupled, largely independent tasks. The robots in this architecture possess a variety of high-level functions that they can perform during a mission, and must at all times select an appropriate action based on the requirements of the mission, the activities of other robots, the current environmental conditions, and their own internal states. Since such cooperative teams often work in dynamic and unpredictable environments, the software architecture allows the team members to respond robustly and reliably to unexpected environmental changes and modifications in the robot team that may occur due to mechanical failure, the learning of new skills, or the addition or removal of robots from the team by human intervention. After presenting ALLIANCE, the author describes in detail the experimental results of an implementation of this architecture on a team of physical mobile robots performing a cooperative box pushing demonstration. These experiments illustrate the ability of ALLIANCE to achieve adaptive, fault-tolerant cooperative control amidst dynamic changes in the capabilities of the robot team.

Parker, L.E.

1998-11-01T23:59:59.000Z

330

Exploiting Neoteric Solvents for Sustainable Catalysis and Reaction Engineering: Opportunities and Challenges  

Science Journals Connector (OSTI)

Several megaton catalytic processes (such as homogeneous hydroformylation of higher olefins, epoxidation of light olefins, and p-xylene oxidation to produce terephthalic acid) exist that produce the essential chemical intermediates for everyday products but present sustainability challenges with respect to reducing environmental footprints and enhancing energy efficiency. ... Effective integration of these elements into a sustainable technology requires a multiscale approach. ... The key challenge for reactor engineering is to establish the scientifically based sustainable technologies necessary for meeting the future energy, environmental, and materials needs of the world. ...

Bala Subramaniam

2010-09-10T23:59:59.000Z

331

JAMES J. SPIVEY J.M. Shivers Professor Department of Chemical...  

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

Developed new graduate-level course in heterogeneous catalysis; responsible for unit operations lab and course. Catalysis research. Conduct research in synthesis gas...

332

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

E-Print Network (OSTI)

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

Scheel, Arnd

333

Thermal Decomposition of Dichlorosilane Investigated by Pulsed Laser Powered Homogeneous Pyrolysis  

E-Print Network (OSTI)

of vacuum flash pyrolysis of SiH 2Cl2. Ban and Gilbert6 observed SiCl2 by mass spectrometry under sili- conThermal Decomposition of Dichlorosilane Investigated by Pulsed Laser Powered Homogeneous Pyrolysis powered homogeneous pyrolysis of dichlorosilane are reported. Pyrolyses at temperatures of 1350 to 1700 K

Swihart, Mark T.

334

CERNA WORKING PAPER SERIES Spatial price homogeneity as a mechanism to reduce the threat of  

E-Print Network (OSTI)

CERNA WORKING PAPER SERIES Spatial price homogeneity as a mechanism to reduce the threat price homogeneity as a mechanism to reduce the threat of regulatory intervention in locally monopolistic to retaliations from local elected officials. When investor-owned monopolies are exposed to this threat

Paris-Sud XI, Université de

335

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

DOE Patents (OSTI)

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

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

2014-04-08T23:59:59.000Z

336

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

E-Print Network (OSTI)

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

Vekilov, Peter

337

Shape from Contour: Straight Homogeneous Generalized Cylinders and Constant Cross Section Generalized Cylinders  

Science Journals Connector (OSTI)

Abstract¿ We analyze the properties of Straight Homogeneous Generalized Cylinders (SHGCs) and Constant Cross Section Generalized Cylinders (CGCs), and derive the types of symmetries that the limb boundaries and cross sections of these objects produce ... Keywords: Shape from contour, staright homogeneous generalized cones, constant cross section generalized cones, symmetry analysis, shape constraints.

Faith Ulupinar; Ramakant Nevatia

1995-02-01T23:59:59.000Z

338

VIBRATION OF RIGID BODIES ON NON-HOMOGENEOUS SEMI-INFINITE ELASTIC MEDIA  

Science Journals Connector (OSTI)

......November 1973 research-article Articles VIBRATION OF RIGID BODIES ON NON-HOMOGENEOUS...problems arising in the theory of the vibration of rigid bodies on non-homogeneous...dealt with the simplest torsional mode vibration. Three cases are considered here: vertical......

A. O. AWOJOBI

1973-11-01T23:59:59.000Z

339

Abstract 64: Development of homogeneous non-radioactive assays for studying histone 3 methyltransferases and demethylases  

Science Journals Connector (OSTI)

...positives/negatives). In this study, we describe homogeneous (mix-and-read) assays for measuring the catalytic activity of...homogeneous assay (AlphaLISA) and time-resolved fluorescence energy transfer (LANCE). The EZH2 complex (which methylates histone...

Mireille Caron; Julie Blouin; Claire Normand; Anne Labonté; Hendrick Plante; Mathieu Arcand; Lucille Beaudet; and Jaime Padrós

2011-04-15T23:59:59.000Z

340

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

SciTech Connect

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

Cheng, A.M.

1992-04-01T23:59:59.000Z

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

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

342

Structure, Thermodynamics and Kinetics of Chemically Heterogeneous Interfaces  

E-Print Network (OSTI)

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

Palafox Hernandez, Jesus Pablo

2011-08-31T23:59:59.000Z

343

MARWIS: A Management Architecture for Heterogeneous Wireless Sensor Networks  

E-Print Network (OSTI)

8. 2 Related Work Most management and code distribution approaches does not support hetero- geneousMARWIS: A Management Architecture for Heterogeneous Wireless Sensor Networks Gerald Wagenknecht Science and Applied Mathematics University of Bern, Switzerland Email: {wagen, anwander, braun, staub

Braun, Torsten

344

Exploiting Heterogeneous Sequence Properties Improves Prediction of Protein Disorder  

E-Print Network (OSTI)

Exploiting Heterogeneous Sequence Properties Improves Prediction of Protein Disorder Zoran disordered regions. Proteins 2005; Suppl 7:176­182. © 2005 Wiley-Liss, Inc. Key words: disorder prediction; intrinsically disor- dered; length dependent predictors INTRODUCTION Intrinsically disordered proteins

Obradovic, Zoran

345

An Intelligent Threat Prevention Framework with Heterogeneous Information  

E-Print Network (OSTI)

An Intelligent Threat Prevention Framework with Heterogeneous Information Wenjun Ma 1 and Weiru Liu 1 Abstract. Three issues usually are associated with threat prevention intelligent surveillance, the de- mand of effectively predicting suspects' intention and ranking the potential threats posed

Liu, Weiru

346

An Advanced Security Infrastructure for Heterogeneous Relational Grid Data Sources  

Science Journals Connector (OSTI)

In this paper we deal with the problem of secure access to metadata information in Grid computing environments. The heterogeneity of the eventual ... database management systems) and the enforcement of security p...

Javier Jaén Martínez; JoséH. Canós

2004-01-01T23:59:59.000Z

347

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

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

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

348

Scaling Laws for the Heterogeneously Heated Free Convective Boundary Layer  

Science Journals Connector (OSTI)

The heterogeneously heated free convective boundary layer (CBL) is investigated by means of dimensional analysis and results from large-eddy simulations (LES) and direct numerical simulations (DNS). The investigated physical model is a CBL that ...

Chiel C. van Heerwaarden; Juan Pedro Mellado; Alberto De Lozar

2014-11-01T23:59:59.000Z

349

Dynamic Heterogeneity-Aware Resource Provisioning in the Cloud  

E-Print Network (OSTI)

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

Boutaba, Raouf

350

CORBA: Integrating Diverse Applications Within Distributed Heterogeneous Environments  

E-Print Network (OSTI)

characteristic of large computer networks such as the Internet, the World Wide Web (WWW), and corporate intranets is that they are heterogeneous. For example, a corporate intranet might be made up of mainframes, UNIX workstations and servers

Reverbel, Francisco

351

CORBA: Integrating Diverse Applications Within Distributed Heterogeneous Environments  

E-Print Network (OSTI)

characteristic of large computer networks such as the Internet, the World Wide Web (WWW), and corporate intranets is that they are heterogeneous. For example, a corporate intranet might be made up of mainframes, UNIX workstationsand servers

Narasimhan, Priya

352

Increasing Stability Reduces Conformational Heterogeneity in a Protein Folding  

E-Print Network (OSTI)

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

353

Laser ignition of a heterogeneous nickel-aluminum system  

Science Journals Connector (OSTI)

The ignition of a heterogeneous nickel—aluminum system by laser radiation is investigated experimentally. The ignition characteristics are investigated as a function of ... the samples. It is established that the...

Yu. S. Naiborodenko; V. M. Filatov

354

Stochastic model of heterogeneity in earthquake slip spatial distributions  

Science Journals Connector (OSTI)

......research-article Seismology Stochastic model of heterogeneity in earthquake slip spatial distributions Daniel Lavallee 1 Pengcheng Liu 1 Ralph J. Archuleta 1 2 1 Institute for Crustal Studies, University of California, Santa Barbara, CA 93106, California......

Daniel Lavallée; Pengcheng Liu; Ralph J. Archuleta

2006-05-01T23:59:59.000Z

355

NMR CHARACTERIZATIONS OF PROPERTIES OF HETEROGENEOUS MEDIA  

SciTech Connect

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

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

2005-01-01T23:59:59.000Z

356

Degradation of 4-chlorophenol from wastewater through heterogeneous Fenton and photo-Fenton process, catalyzed by Al–Fe PILC  

Science Journals Connector (OSTI)

Clay pillared with Al–Fe was synthesized as a catalyst for (photo)-Fenton oxidation of 4-chlorophenol. The catalyst was characterized by X-ray diffraction, nitrogen physisorption, diffuse reflectance UV–VIS spectroscopy and temperature-programmed reduction. The chemical composition, indicating the incorporation of Al and Fe within the clay structure, was determined by ICP-OES. The oxidation of 4-chlorophenol was faster in the UV-A assisted process, followed by VIS-light assisted and “dark” processes. All the processes begin with an induction period, followed by a fast oxidation step. Iron leaching is observed for all the systems and was mainly attributed to proton and reductive dissolution processes. Proton dissolution is very slow and could be responsible for the induction period. The reductive dissolution is induced in the presence of 4-chlorocatechol, the main reaction intermediate. The dissolved iron ions are able to catalyze the homogeneous Fenton-like process. All the experimental findings suggest that a combined heterogeneous–homogeneous mechanism could be envisaged for the studied reaction system.

Cezar Catrinescu; Daniela Arsene; Petru Apopei; Carmen Teodosiu

2012-01-01T23:59:59.000Z

357

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

SciTech Connect

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

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

1985-08-01T23:59:59.000Z

358

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

SciTech Connect

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

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

2008-02-01T23:59:59.000Z

359

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

360

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

DOE Patents (OSTI)

The present invention provides new catalyst formats which comprise a supported catalyst tethered to a second and different catalyst by a suitable tethering ligand. A preferred system comprises a heterogeneous supported metal catalyst tethered to a homogeneous catalyst. This combination of homogeneous and heterogeneous catalysts has a sufficient lifetime and unusually high catalytic activity in arene hydrogenations, and potentially many other reactions as well, including, but not limited to hydroformylation, hydrosilication, olefin oxidation, isomerization, hydrocyanidation, olefin metathesis, olefin polymerization, carbonylation, enantioselective catalysis and photoduplication. These catalysts are easily separated from the products, and can be reused repeatedly, making these systems very economical. 2 figs.

Angelici, R.J.; Gao, H.

1998-08-04T23:59:59.000Z

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


361

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

362

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

SciTech Connect

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

363

Charged particles in higher dimensional homogeneous gravitational field: self-energy and self-force  

Science Journals Connector (OSTI)

A problem of self-energy and self-force for a charged point-like particle in a higher dimensional homogeneous gravitational field is considered. We study two cases, when a particle has the usual electric charg...

Valeri P. Frolov; Andrei Zelnikov

2014-10-01T23:59:59.000Z

364

On mechanisms of formation of environmentally harmful compounds in homogeneous combustors  

Science Journals Connector (OSTI)

A kinetic model is developed for calculating the emission characteristics of homogeneous combustors using methane and synthesis gas (syngas) as a fuel. The model is ... OH in laminar flames and in the Bunsen burner

V. E. Kozlov; A. M. Starik; N. S. Titova…

2013-09-01T23:59:59.000Z

365

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

E-Print Network (OSTI)

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

Mair, Patrick; Leeuw, Jan de

2008-01-01T23:59:59.000Z

366

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

E-Print Network (OSTI)

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

Patrick Mair; Jan de Leeuw

2011-01-01T23:59:59.000Z

367

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

E-Print Network (OSTI)

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

Murayama, Hitoshi

368

Homogeneous geodesics and the critical points of the restricted Finsler function  

Science Journals Connector (OSTI)

In this paperwe study the set of homogeneous geodesics of a left-invariant Finsler metric on Lie groups. We first give a simple criterion that characterizes geodesic vectors. We extend J. Szenthe’s result on h...

Parastoo Habibi; Dariush Latifi…

2011-02-01T23:59:59.000Z

369

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

SciTech Connect

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

Cutler, Alan R.

2001-04-14T23:59:59.000Z

370

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

E-Print Network (OSTI)

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

A. A. Magazev; I. V. Shirokov

2007-03-21T23:59:59.000Z

371

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

E-Print Network (OSTI)

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

Kondagunta, Veeraraghava Gopal

2012-06-07T23:59:59.000Z

372

Testing the gamma-ray burst variability/peak luminosity correlation on a Swift homogeneous sample  

E-Print Network (OSTI)

We test the gamma-ray burst correlation between temporal variability and peak luminosity of the $\\gamma$-ray profile on a homogeneous sample of 36 Swift/BAT GRBs with firm redshift determination. This is the first time that this correlation can be tested on a homogeneous data sample. The correlation is confirmed, as long as the 6 GRBs with low luminosity (tested on low-luminosity GRBs. Our results show that these GRBs are definite outliers.

D. Rizzuto; C. Guidorzi; P. Romano; S. Covino; S. Campana; M. Capalbi; G. Chincarini; G. Cusumano; D. Fugazza; V. Mangano; A. Moretti; M. Perri; G. Tagliaferri

2007-04-19T23:59:59.000Z

373

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

E-Print Network (OSTI)

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

Del Carmen, Maria Yanina

1995-01-01T23:59:59.000Z

374

Lattice Boltzmann scheme for fluids with dynamic heterogeneities  

Science Journals Connector (OSTI)

We introduce and discuss a three-dimensional mesoscopic lattice Boltzmann model for the numerical simulation of strongly-interacting fluids with dynamic inhomogeneities. The model is based on an extension of the standard lattice Boltzmann dynamics in which streaming between neighboring lattice sites is constrained by the value of the nonlocal density of the surrounding fluid. The resulting dynamics exhibits typical features of dynamically heterogeneous fluids, such as long-time relaxation, non-Gaussian density distributions and dynamic heterogeneities. Due to its intrinsically parallel dynamics and absence of statistical noise, the method is expected to compute significantly faster than molecular dynamics, Monte Carlo, and lattice glass models.

A. Lamura and S. Succi

2006-06-28T23:59:59.000Z

375

Protein Folding Rates Correlate with Heterogeneity of Folding Mechanism  

Science Journals Connector (OSTI)

By observing trends in the folding kinetics of experimental 2-state proteins at their transition midpoints, and by observing trends in the barrier heights of numerous simulations of coarse-grained, C? model G? proteins, we show that folding rates correlate with the degree of heterogeneity in the formation of native contacts. Statistically significant correlations are observed between folding rates and measures of heterogeneity inherent in the native topology, as well as between rates and the variance in the distribution of either experimentally measured or simulated ? values.

B. Öztop; M. R. Ejtehadi; S. S. Plotkin

2004-11-12T23:59:59.000Z

376

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

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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

377

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

378

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)

379

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,

380

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

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

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

382

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)

383

DNA heterogeneity and phosphorylation unveiled by single-molecule electrophoresis  

E-Print Network (OSTI)

scatter plots. Materials and Methods Nucleic Acid Preparations. Synthetic DNA oligonucleotides were purchased from different commercial suppliers. DNA prepared by PCR was amplified with synthetic primers fromDNA heterogeneity and phosphorylation unveiled by single-molecule electrophoresis Hui Wang*, James

384

An analysis and hypothesis generation platform for heterogeneous cancer  

E-Print Network (OSTI)

An analysis and hypothesis generation platform for heterogeneous cancer databases. Philip Roy QUINLAN a,1, Alastair THOMPSON a and Chris REED b a Dundee Cancer Centre, University of Dundee, Ninewells Hospital, Dundee b School of Computing, University of Dundee, Dundee Abstract. The field of cancer research

Reed, Chris

385

Coordinated Output Regulation of Multiple Heterogeneous Linear Systems  

E-Print Network (OSTI)

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

Dimarogonas, Dimos

386

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

E-Print Network (OSTI)

the hu- manoid robot and the wheeled robot track a moving ball, which is to be approached and kickedTowards Cooperation of Heterogeneous, Autonomous Robots: A Case Study of Humanoid and Wheeled Robots Jutta Kiener and Oskar von Stryk Technische Universit¨at Darmstadt Simulation, Systems

Stryk, Oskar von

387

ADAPTIVE ONLINE ENERGY SAVING FOR HETEROGENEOUS SENSOR Meikang Qiu1  

E-Print Network (OSTI)

ADAPTIVE ONLINE ENERGY SAVING FOR HETEROGENEOUS SENSOR NETWORKS Meikang Qiu1 Jingtong Hu2 Edwin H-to-predict environments and have limited lifetime. We use a novel adaptive online energy saving (AOES) algorithm to save as a probabilistic random variable to save energy by se- lecting the best mode assignment for each node, which

Sha, Edwin

388

Energy Consumption Characteriation of Heterogeneous Servers School of Computer Science  

E-Print Network (OSTI)

Energy Consumption Characteriation of Heterogeneous Servers Xiao Zhang School of Computer Science Machine between servers to save energy. An accurate energy consumption model is the basic of energy management. Most past studies show that energy consumption has linear relation with resource utilization. We

Qin, Xiao

389

Uni ed Support for Heterogeneous Security Policies in Distributed Systems  

E-Print Network (OSTI)

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

Minsky, Naftaly

390

Technology Offer Heterogeneous Leaching Free Pd-Catalyst  

E-Print Network (OSTI)

Technology Offer Heterogeneous Leaching Free Pd-Catalyst For further information please contact) of the carrier particles and the catalyst Potential Fields of Application Production of substituted biphenyls-coupling reactions Overview The present invention relates to non-leaching Pd-catalysts for C-C, C-O or C-N couplings

391

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 category includes all step- up and step-down transmission substations, as well as a number of distribution substations indeed. Nevertheless, the current trend in electric power Engineering moves in another direction

Colominas, Ignasi

392

Single-pulse Raman scattering studies of heterogeneous explosive materials  

SciTech Connect

Raman scattering from ambient and shock-loaded heterogeneous (compressed pure polycrystalline) explosive materials has been examined using single-pulse laser excitation. In the case of triamino-trinitrobenzene (TATB), intense nonlinear scattering at 1170 cm/sup -1/ has been observed.

Trott, W.M.; Renlund, A.M.

1985-05-15T23:59:59.000Z

393

Hydrocarbons Heterogeneous Pyrolysis: Experiments and Modeling for Scramjet Thermal Management  

E-Print Network (OSTI)

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

Paris-Sud XI, Université de

394

A Gossip Algorithm for Heterogeneous Multi-Vehicle Routing Problems  

E-Print Network (OSTI)

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

Bullo, Francesco

395

Mechanistic Foam Flow Simulation in Heterogeneous and Multidimensional Porous Media  

E-Print Network (OSTI)

that is analogous to energy and species mass balances7, 8. Accordingly, a separate conservation equation is written flow is multidimensional and the porous medium is heterogeneous. We have incorporated a conservation are predicted, regardless of whether the layers are communicating or isolated. Introduction Field application

Patzek, Tadeusz W.

396

Single molecule tracking of heterogeneous diffusion Jianshu Cao  

E-Print Network (OSTI)

showing no sign of heterogeneities in the ensemble measurement of the diffusion constant. The signature liquids, and colloidal fluids 21­25 . Zwanzig studied percolation in a dynamic disordered system using in the membrane structure 33,34 . Some proteins are transiently confined to small island domains bounded

Cao, Jianshu

397

Modeling Structural Heterogeneity in Proteins From X-Ray Data  

E-Print Network (OSTI)

Modeling Structural Heterogeneity in Proteins From X-Ray Data Ankur Dhanik1 , Henry van den Bedem2: In a crystallographic experiment, a protein is precipitated to obtain a crystalline sample (crystal) containing many determination and density calculation. The protein conformation is modeled by placing the atoms in 3-D space

Pratt, Vaughan

398

Modeling mesoscopic attenuation in a highly heterogeneous Biot's ...  

E-Print Network (OSTI)

mic frequencies is known as “mesoscopic loss”, and is caused by the presence of ... (2007). Then, it is applied to simulate the seismic response of an heterogeneous CO2 ... with this numerical procedure measured in the energy norm is of order h (Ha T. et al. ..... mic modeling for monitoring co2 storage: Pure Appl. Geophys.,.

2009-10-27T23:59:59.000Z

399

TURBULENT SHEAR STRESS IN HETEROGENEOUS SEDIMENT-LADEN FLOWS  

E-Print Network (OSTI)

TURBULENT SHEAR STRESS IN HETEROGENEOUS SEDIMENT-LADEN FLOWS By Hyoseop Woo,1 Associate Member are the beginning of motion of sediment particles and sediment transport in alluvial channels. If shear stress can be well defined in clear-water flows, compar- atively little is known about shear stresses in sediment

Julien, Pierre Y.

400

Cellubrevin-targeted Fluorescence Uncovers Heterogeneity in the Recycling Endosomes*  

E-Print Network (OSTI)

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

Machen, Terry E.

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

MODELING PHOTOSYNTHESIS OF HETEROGENEOUS ROSE CROP CANOPIES IN THE GREENHOUSE  

E-Print Network (OSTI)

MODELING PHOTOSYNTHESIS OF HETEROGENEOUS ROSE CROP CANOPIES IN THE GREENHOUSE Soo-Hyung Kim and J. Heinrich Lieth Department of Environmental Horticulture University of California Davis, CA 95616-8587, USA training system ("bent canopy") is widely used in greenhouse rose production. The bent canopy consists

Lieth, J. Heinrich

402

Power-Aware Dynamic Task Scheduling for Heterogeneous Accelerated Clusters  

E-Print Network (OSTI)

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

403

Distributed dynamic load balancing for pipelined computations on heterogeneous systems  

Science Journals Connector (OSTI)

One of the most significant causes for performance degradation of scientific and engineering applications on high performance computing systems is the uneven distribution of the computational work to the resources of the system. This effect, which is ... Keywords: Distributed model, Dynamic load balancing algorithms, Loops with dependencies, Master-worker model, Non-dedicated heterogeneous systems, Synchronization, Weighting

Ioannis Riakiotakis; Florina M. Ciorba; Theodore Andronikos; George Papakonstantinou

2011-10-01T23:59:59.000Z

404

Hybrid Heterogeneous Energy Supply Networks Farinaz Koushanfar and Azalia Mirhoseini  

E-Print Network (OSTI)

Hybrid Heterogeneous Energy Supply Networks Farinaz Koushanfar and Azalia Mirhoseini Department--Efficient energy supply, storage, and distribution are key technical challenges for design and operation of electronic systems. In particular, energy supply is the most scarce resource and constraint for mobile

405

Anthropogenic Biomes ver. 1 Anthropogenic biomes represent heterogeneous  

E-Print Network (OSTI)

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

Columbia University

406

Growth Properties of Artificial Heterogeneous Human Colon Tumors  

Science Journals Connector (OSTI)

...AHT, artificial heterogeneous tumor; CFE, colony-forming efficiency; CC, carrying...counted by eye for estimation of the overall CFE from each sample. Each colony was visually...confident that not only could the overall CFE from each tumor be measured, but that we...

John T. Leith; Seth Michelson; Lynn E. Faulkner; Sarah F. Bliven

1987-02-15T23:59:59.000Z

407

Reliability of Heterogeneous Distributed Computing Systems in the Presence  

E-Print Network (OSTI)

Reliability of Heterogeneous Distributed Computing Systems in the Presence of Correlated Failures of correlated failures are also investigated. Index Terms--Distributed computing, load balancing, reliability Jorge E. Pezoa, Member, IEEE and Majeed M. Hayat, Fellow, IEEE Abstract--While the reliability

Hayat, Majeed M.

408

Measuring Heterogeneity in Forensic Databases Using Hierarchical Bayes Models  

E-Print Network (OSTI)

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

409

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

SciTech Connect

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

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

2010-01-01T23:59:59.000Z

410

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

E-Print Network (OSTI)

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

411

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

412

The Hierarchy of Adsorption Models for Laterally Interacting Molecules on Heterogeneous Surfaces  

Science Journals Connector (OSTI)

Real adsorbents are heterogeneous, therefore, the computation of the adsorption characteristics for any concentration of adsorbate must take account of the joint effect of the lateral interaction between adsorbed molecules and surface heterogeneity. The ...

Yu. K. Tovbin

1997-03-05T23:59:59.000Z

413

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

E-Print Network (OSTI)

This dissertation consists of three essays on the heterogeneous reactions of firms to shocks, with particular empirical applications to the Chilean economy. The first essay presents a model of heterogeneity in an economy ...

Landerretche, Oscar

2006-01-01T23:59:59.000Z

414

E-Print Network 3.0 - adaptive heterogeneous multi-robot Sample...  

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

heterogeneous multi-robot Search Powered by Explorit Topic List Advanced Search Sample search results for: adaptive heterogeneous multi-robot Page: << < 1 2 3 4 5 > >> 1 (as of 8...

415

ENHANCING MARKETING WITH ENGINEERING: OPTIMAL PRODUCT LINE DESIGN FOR HETEROGENEOUS MARKETS  

E-Print Network (OSTI)

ENHANCING MARKETING WITH ENGINEERING: OPTIMAL PRODUCT LINE DESIGN FOR HETEROGENEOUS MARKETS Jeremy Engineering University of Michigan Summer 2010 Forthcoming in International Journal of Research in Marketing of Business. #12;- 1 - ENHANCING MARKETING WITH ENGINEERING: OPTIMAL PRODUCT LINE DESIGN FOR HETEROGENEOUS

Papalambros, Panos

416

Enhancing marketing with engineering: Optimal product line design for heterogeneous markets  

E-Print Network (OSTI)

Enhancing marketing with engineering: Optimal product line design for heterogeneous markets Jeremy design and development often require a balance of technical and market tradeoffs. Quantitative methods with an eye toward market consequences, particularly when heterogeneous market preferences make

Michalek, Jeremy J.

417

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

E-Print Network (OSTI)

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

Boyer, Edmond

418

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

SciTech Connect

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

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

2009-09-11T23:59:59.000Z

419

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

SciTech Connect

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

420

Development Plus Kinetic and Mechanistic Studies of a Prototype Supported-Nanoparticle Heterogeneous Catalyst  

E-Print Network (OSTI)

-Nanoparticle Heterogeneous Catalyst Formation System in Contact with Solution: Ir(1,5-COD)Cl/ -Al2O3 and Its Reduction by H2 to prepare the next generation of improved, supported-nanoparticle heterogeneous catalysts. It is precisely are eight criteria defining a prototype system for supported-nanoparticle heterogeneous catalyst formation

Frenkel, Anatoly

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

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

E-Print Network (OSTI)

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

Nicolas, Chamot-Rooke

422

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

E-Print Network (OSTI)

It is known that all spatially homogeneous solutions of the vacuum Einstein equations in four dimensions which exist for an infinite proper time towards the future are future geodesically complete. This paper investigates whether the analogous statement holds in higher dimensions. A positive answer to this question is obtained for a large class of models which can be studied with the help of Kaluza-Klein reduction to solutions of the Einstein-scalar field equations in four dimensions. The proof of this result makes use of a criterion for geodesic completeness which is applicable to more general spatially homogeneous models.

Arne Goedeke; Alan D. Rendall

2010-02-21T23:59:59.000Z

423

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

424

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

425

Fluxes of water and energy in physically heterogeneous environments  

SciTech Connect

This is the final report of a one-year, Laboratory Directed Research and Development (LDRD) project at Los Alamos National Laboratory (LANL). Fluxes of water and energy at the near-surface environment are tightly interrelated with a heterogeneous vegetation pattern that is a mosaic of tree canopies and intercanopy area. The objective was to improve the ability to predict these interrelationships, which are not well quantified. The authors (1) quantified how vegetation overstory determines the patterns of soil moisture and near-ground solar radiation, (2) developed spatial neighborhood analyses that demonstrated how woody plants exploit canopy/intercanopy heterogeneity, (3) developed a spatially explicit model for predicting near-ground solar radiation for sites along a grassland-forest continuum, (4) developed a water balance model that predicted temporal shifts in soil moisture between canopy and intercanopy patches, and (5) used the collective results to assess large-scale ecosystem responses to climate variations that lead to accelerated soil erosion.

Breshears, D.D.; Barnes, F.J.; Davenport, D.W. [and others

1997-11-01T23:59:59.000Z

426

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

427

SU?E?T?348: Measurement?Guided 4D VMAT Dose Reconstruction on an Arbitrary Homogeneous Dataset  

Science Journals Connector (OSTI)

Purpose: To develop and validate a VMAT QA tool that takes as input a 2D low?density (?10 mm) empirical dose map from a commercial helical diode array and outputs a high density volumetric time?resolved (4D) dose matrix on an arbitrary patient dataset. At first the method validation is limited to a homogeneous ‘patient’. Methods: A VMAT treatment is delivered to a diode array (ArcCHECK Sun Nuclear Corp. Melbourne FL). 3DVH software (Sun Nuclear) derives the high?density volumetric dose using measurement?guided dose reconstruction (MGDR). MGDR cylindrical phantom results are then used to perturb the 3D TPS dose on the patient dataset producing a semi?empirical volumetric dose grid. Four?dimensional dose reconstruction on the patient is also possible by morphing the sub?beam instead of composite dose. For validation TG?119 structures and objectives were used. 3DVH and TPS cumulative point doses were compared to ion chamber in a cube water?equivalent phantom (‘patient’). The shape of the phantom is different from the ArcCHECK and the targets were placed asymmetrically. Ion chamber dose sampled at 10Hz was compared to time?resolved 3DVH point doses. Coronal and sagittal absolute film dose distributions in the cube were compared with 3DVH and TPS. Results: Across four TG?119 plans the average PTV point dose difference in the cube between 3DVH and ion chamber is 0.0±0.9%. Average film vs. 3DVH gamma analysis passing rates are 88.6 96.1 and 99.5% for 1%/2mm 2%/2mm and 3%/3mm criteria respectively. 4D MGDR was also sufficiently accurate. Conclusions: Even for a well?commissioned TPS comparison metrics show on average better agreement between MGDR and measurement compared to MGDR and TPS on the arbitrary?shaped phantom (‘patient’). The method requires no more accelerator time than standard QA while producing more clinically relevant information. Validation in a heterogeneous thoracic phantom is under way as is ultimate application to virtual motion studies. Supported in part by a grant from Sun Nuclear Corp.

D Opp; J Robinson; B Nelms; G Zhang; V Feygelman

2012-01-01T23:59:59.000Z

428

Fluctuation relation and heterogeneous superdiffusion in glassy transport  

Science Journals Connector (OSTI)

Current fluctuations and related steady-state fluctuation relation are investigated in simple coarse-grained lattice-gas analogs of a non-Newtonian fluid driven by a constant and uniform force field in two regimes of small entropy production. Non-Gaussian current fluctuations and deviations from fluctuation relation are observed and related to the existence of growing amorphous correlations and heterogeneous anomalous diffusion regimes.

Mauro Sellitto

2009-07-27T23:59:59.000Z

429

Fluctuation relation and heterogeneous superdiffusion in glassy transport  

E-Print Network (OSTI)

Current fluctuations and related steady state fluctuation relation are investigated in simple coarse-grained lattice-gas analogs of a non-Newtonian fluid driven by a constant and uniform force field, in two regimes of small entropy production. Non-Gaussian current fluctuations and deviations from fluctuation relation are observed and related to the existence of growing amorphous correlations and heterogeneous anomalous diffusion regimes.

Mauro Sellitto

2009-03-19T23:59:59.000Z

430

The biodegradation of organic acids by a heterogeneous bacterial culture  

E-Print Network (OSTI)

- tion of fatty acids results in multiple cleavage of the molecules to form shorter chain acids. It has been found (1I) that ethanoic and butanoic are the principle volatile acids present during digestion of sewage sludge while propanoic and pentanoic... was developed from a heterogeneous culture found in a sewage plant effluent. The culture was developed in a bench scale continuous flow activated. sludge reactor, and individual studies were made in a bench scale aerated batch reactor. The acids used were...

Tyer, Bobby Ray

1968-01-01T23:59:59.000Z

431

Homogeneous Bottleneck Model of Matrix-assisted Ultraviolet Laser Desorption of  

E-Print Network (OSTI)

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

Vertes, Akos

432

Genetically Engineered Elastin-Protein A Fusion as a Universal Platform for Homogeneous,  

E-Print Network (OSTI)

Genetically Engineered Elastin-Protein A Fusion as a Universal Platform for Homogeneous, Phase-separation Immunoassay Jae-Young Kim,, Sean O'Malley,§ Ashok Mulchandani,*, and Wilfred Chen*, Department of Chemical, California 92521, and Hawaii Biotech Inc., Aiea, Hawaii 96701 A simple and universal platform for competitive

Chen, Wilfred

433

Traveltime approximation for a reflected wave in a homogeneous anisotropic elastic layer  

Science Journals Connector (OSTI)

......reflected wave in a homogeneous anisotropic elastic layer M. Zillmer...A review of wave motion in anisotropic and cracked elastic-media...1995. Seismic anisotropy of shales, J. geophys. Res., 100...body waves in arbitrarily anisotropic media, in, Propagation of......

M. Zillmer; B. M. Kashtan

2002-10-01T23:59:59.000Z

434

Lattice Boltzmann simulations of decaying homogeneous isotropic turbulence Huidan Yu,1,  

E-Print Network (OSTI)

Lattice Boltzmann simulations of decaying homogeneous isotropic turbulence Huidan Yu,1, * Sharath S is investigated to evaluate the capability of the lattice Boltzmann method in turbulence. In the inertial frame that the lattice Boltzmann method captures im- portant features of decaying turbulence. DOI: 10.1103/PhysRevE.71

Luo, Li-Shi

435

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

SciTech Connect

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

436

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

E-Print Network (OSTI)

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

437

The Effect of Flow Unsteadiness on the Homogeneous Nucleation of Water Droplets in Steam Turbines  

Science Journals Connector (OSTI)

...Unsteadiness on the Homogeneous Nucleation of Water Droplets in Steam Turbines Abhijit Guha John Young The paper describes a new theory of the formation and growth of water droplets in multistage steam turbines. The essence of the theory is that large-scale static...

1994-01-01T23:59:59.000Z

438

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

439

Enhanced HFIR overpower margin through improvements in fuel plate homogeneity inspection  

SciTech Connect

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

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

1995-09-01T23:59:59.000Z

440

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

E-Print Network (OSTI)

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

Francisco Astorga; Olivier Sarbach; Thomas Zannias

2014-06-14T23:59:59.000Z

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

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

E-Print Network (OSTI)

temperatures, nickel oxide dissolves in the melt. This slow loss of active material contributes to an increase as compared to nickel oxide. The search for alternate cathode materials could be simplified through the use-phase homogeneous model was developed to simulate the performance of the molten carbonate fuel cell MCFC cathode

Popov, Branko N.

442

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

E-Print Network (OSTI)

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

Iglesia, Enrique

443

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

Science Journals Connector (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

444

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

E-Print Network (OSTI)

ELECTRICAL IMPEDANCE MAMMOGRAPHY Forward problem for homogeneous and 3-D sphere Jakub Vel Prague, October 15, 2014 J. Vel´imsk´y (CUP) Electrical Impedance Mammography Prague, 15.10.2014 1 / 26 and SH-FE discretization Remarks on the inverse problem Current status J. Vel´imsk´y (CUP) Electrical

Cerveny, Vlastislav

445

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

E-Print Network (OSTI)

Statistical fracture modeling: crack path and fracture criteria with application to homogeneous; accepted 23 January 2002 Abstract Analysis has been performed on fracture initiation near a crack in a brittle material with strength described by Weibull statistics. This nonlocal fracture model allows

Ritchie, Robert

446

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

E-Print Network (OSTI)

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

Anderson, Timothy J.

447

Optimization of the structural Gabor functions in a homogeneous velocity model  

E-Print Network (OSTI)

Optimization of the structural Gabor functions in a homogeneous velocity model for a zero-o#11;set functions should be optimized, and the Gabor functions should form a frame. We present a simple attempt functions and the space{wavenumber lattice of their central points are optimized analytically

Cerveny, Vlastislav

448

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

E-Print Network (OSTI)

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

449

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

450

Microfluidic Assembly of Homogeneous and Janus Colloid-Filled Hydrogel Granules  

E-Print Network (OSTI)

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

Lewis, Jennifer

451

The Condensate Equation for non-homogeneous Andre F. Verbeure1  

E-Print Network (OSTI)

The Condensate Equation for non-homogeneous Bosons Andr´e F. Verbeure1 Institute for Theoretical)-condensation. This phe- nomenon is accompanied with spontaneous breaking of the translation symmetry down of the condensate equation for these systems. We discuss model applications. KEY WORDS: Bose- Einstein condensation

452

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

E-Print Network (OSTI)

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

Brandsma, Theo

453

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

E-Print Network (OSTI)

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

Oughton, Sean

454

Development of a navigation system for heterogeneous mobile robots  

Science Journals Connector (OSTI)

Navigation systems often play an important role in mobile robot control. Many existing mobile robot navigation systems have been implemented and tested for particular types of robots. However, in some implementations, such as heterogeneous multi-robot systems, a generic navigation system can offer potential advantages. In such applications, a generic navigation system should be able account for robots with varying size, shape, drive type and sensor quantities. Additionally, it should be capable of offering a high degree of flexibility for navigation in known and unknown environments. Hence, a single generic navigation system that combines the benefits of reactive and deliberative control has been developed for heterogeneous mobile robots. The design of the hierarchical hybrid navigation system is based on the A* algorithm, a polar histogram and a modified dynamic window approach. Simulation experiments with three heterogeneous robots in a range of environments have been conducted. Performance of reactive navigation and hybrid reactive-deliberative navigation in known and unknown environments is evaluated. Favourable results are achieved with the developed reactive system. Hybrid reactive-deliberative navigation offers improved performance over reactive navigation in known environments. Deliberative control does not affect performance significantly in unknown environments. Initial hardware experiments demonstrate that the navigation system can work on real robots.

Praneel Chand; Dale A. Carnegie

2011-01-01T23:59:59.000Z

455

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

SciTech Connect

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

Cheng, A.M.

1992-04-01T23:59:59.000Z

456

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

E-Print Network (OSTI)

Tunable Solvents for Homogeneous Catalyst Recycle Jie Lu, Michael J. Lazzaroni, Jason P. Hallett-0100 A novel class of tunable solvents facilitates recycle of homogeneous catalysts for both economic-soluble catalysts and moderately hydrophobic substrates can be run homoge- neously, with subsequent phase separation

457

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

E-Print Network (OSTI)

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

Elperin, Tov

458

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

SciTech Connect

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

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

1988-11-01T23:59:59.000Z

459

Critical Dynamics of Spontaneous Symmetry Breaking in a Homogeneous Bose gas  

E-Print Network (OSTI)

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

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

2014-10-30T23:59:59.000Z

460

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

E-Print Network (OSTI)

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

Fioralba Cakoni; Houssem Haddar; Isaac Harris

2014-10-14T23:59:59.000Z

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


461

Analytical formulation of 3D dynamic homogenization for periodic elastic systems  

E-Print Network (OSTI)

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

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

2012-01-13T23:59:59.000Z

462

Some mismatches occurred when simulating fractured reservoirs as homogeneous porous media  

SciTech Connect

The understanding of transport processes that occur in naturally fractured geothermal systems is far from being complete. Often, evaluation and numerical simulations of fractured geothermal reservoirs, are carried out by assuming equivalent porous media and homogeneous petrophysical properties within big matrix blocks. The purpose of this paper, is to present a comparison between results obtained from numerical studies of a naturally fractured reservoir treated as a simple porous medium and the simulation of some real aspects of the fractured reservoir. A general conclusion outlines the great practical importance of considering even approximately, the true nature of such systems. Our results show that the homogeneous simplified evaluation of the energy resource in a fractured system, could result in unrealistic estimates of the reservoir capacity to generate electricity.

Mario Cesar Suarez Arriaga; Fernando Samaniego V.; Fernando Rodriguez

1996-01-24T23:59:59.000Z

463

A heterogeneous hierarchical architecture for real-time computing  

SciTech Connect

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

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

1988-12-01T23:59:59.000Z

464

A microrheological study of hydrogel kinetics and micro-heterogeneity  

E-Print Network (OSTI)

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

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

2014-05-27T23:59:59.000Z

465

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

SciTech Connect

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

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

2014-05-15T23:59:59.000Z

466

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

E-Print Network (OSTI)

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

Shcherbakov, Alexey A

2015-01-01T23:59:59.000Z

467

Beam Homogeneity Dependence on the Magnetic Filter Field at the IPP Test Facility MANITU  

SciTech Connect

The homogeneity of the extracted current density from the large RF driven negative hydrogen ion sources of the ITER neutral beam system is a critical issue for the transmission of the negative ion beam through the accelerator and the beamline components. As a first test, the beam homogeneity at the IPP long pulse test facility MANITU is measured by means of the divergence and the stripping profiles obtained with a spatially resolved Doppler-shift spectroscopy system. Since MANITU is typically operating below the optimum perveance, an increase in the divergence corresponds to a lower local extracted negative ion current density if the extraction voltage is constant. The beam H{sub {alpha}} Doppler-shift spectroscopy is a rather simple tool, as no absolute calibration - both for the wavelength and the emission - is necessary. Even no relative calibration of the different used lines of sight is necessary for divergence and stripping profiles as these quantities can be obtained by the line broadening of the Doppler-shifted peak and the ratio of the integral of the stripping peak to the integral of the Doppler-shifted peak, respectively. The paper describes the H{sub {alpha}} MANITU Doppler-shift spectroscopy system which is now operating routinely and the evaluation methods of the divergence and the stripping profiles. Beam homogeneity measurements are presented for different extraction areas and magnetic filter field configurations both for Hydrogen and Deuterium operation; the results are compared with homogeneity measurements of the source plasma. The stripping loss measurements are compared with model calculations.

Franzen, P.; Fantz, U. [Max-Planck-Institut fuer Plasmaphysik, EURATOM Association, PO Box 1533, 85740 Garching (Germany)

2011-09-26T23:59:59.000Z

468

Mathematical modeling of heterogeneous detonation in gas suspensions of aluminum and coal-dust particles  

SciTech Connect

Results of investigations performed by the authors in the field of theoretical and numerical modeling of heterogeneous detonation of reacting gas suspensions since 2005 are systematized.

Fedorov, A.V.; Fomin, V.M.; Khmel, T.A. [Russian Academy of Sciences, Novosibirsk (Russian Federation)

2009-07-15T23:59:59.000Z

469

E-Print Network 3.0 - aquifer heterogeneity final Sample Search...  

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

-30 may-1th june 2006, Dijon, France Summary: is considered like a heterogeneous aquifer: permeability tensor and salt water interface position could... International symposium -...

470

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

E-Print Network (OSTI)

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

Hamilton, Neil G.

2010-01-01T23:59:59.000Z

471

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

E-Print Network (OSTI)

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

Nakagawa, S.

2010-01-01T23:59:59.000Z

472

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

E-Print Network (OSTI)

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

Boehning, Dankmar

473

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

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

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

474

Division Site  

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

Novel Synthetic Methods for Homogeneous and Heterogeneous Catalysts Novel Synthetic Methods for Homogeneous and Heterogeneous Catalysts Our research is directed at developing novel synthetic methods for homogeneous and heterogeneous catalysts. To that end, we are particularly interested in developing well-defined and predictive synthetic routes to pure metals, semiconductors, and insulators. Current projects include the vapor-phase synthesis of photon-harvesting materials and the controlled synthesis of supported first-row transition metal nanoparticles for catalysis. synthetic methods for homogeneous catalysts Our vapor-phase synthesis program is directed at synthesizing higher-order (3 or more elemental components), kinetically stable materials for photon-harvesting (PH) applications such as photocatalysis and photovoltaics. The versatility of solution phase chemical synthesis has yet to be achieved in advanced inorganic materials. The few higher order PH absorber materials which have been reported display unique combinations of thermodynamic stability and kinetic accessibility. We are interested in moving off the phase diagrams to synthesize novel materials with improved photon harvesting abilities for catalysis.

475

Fuel loading and homogeneity analysis of HFIR design fuel plates loaded with uranium silicide fuel  

SciTech Connect

Twelve nuclear reactor fuel plates were analyzed for fuel loading and fuel loading homogeneity by measuring the attenuation of a collimated X-ray beam as it passed through the plates. The plates were identical to those used by the High Flux Isotope Reactor (HFIR) but were loaded with uranium silicide rather than with HFIR`s uranium oxide fuel. Systematic deviations from nominal fuel loading were observed as higher loading near the center of the plates and underloading near the radial edges. These deviations were within those allowed by HFIR specifications. The report begins with a brief background on the thermal-hydraulic uncertainty analysis for the Advanced Neutron Source (ANS) Reactor that motivated a statistical description of fuel loading and homogeneity. The body of the report addresses the homogeneity measurement techniques employed, the numerical correction required to account for a difference in fuel types, and the statistical analysis of the resulting data. This statistical analysis pertains to local variation in fuel loading, as well as to ``hot segment`` analysis of narrow axial regions along the plate and ``hot streak`` analysis, the cumulative effect of hot segment loading variation. The data for all twelve plates were compiled and divided into 20 regions for analysis, with each region represented by a mean and a standard deviation to report percent deviation from nominal fuel loading. The central regions of the plates showed mean values of about +3% deviation, while the edge regions showed mean values of about {minus}7% deviation. The data within these regions roughly approximated random samplings from normal distributions, although the chi-square ({chi}{sup 2}) test for goodness of fit to normal distributions was not satisfied.

Blumenfeld, P.E.

1995-08-01T23:59:59.000Z

476

Homogeneous carbon doping of magnesium diboride by high-temperature, high-pressure synthesis  

SciTech Connect

We have used high-pressure, high-temperature synthesis at 1500–1700?°C and 10?MPa to create homogeneously C-substituted MgB{sub 2} from a B{sub 4}C + Mg mixture. X-ray diffraction analysis showed large peak-shifts consistent with a decrease in the a lattice parameter for the B{sub 4}C-derived MgB{sub 2} as compared to an undoped sample (0.033–0.037?Å, depending on the sample). Microstructural investigation showed a three-phase mixture in the B{sub 4}C-derived ingots: MgB{sub 2?x}C{sub x} (with 0.178?homogeneity of C-doping in the MgB{sub 2}. The width of the T{sub c} distribution for the C-doped MgB{sub 2} was only 3–6?K with a full-width half maximum (FWHM) of 1.4?K, compared to a width of 2.5?K and a FWHM of 0.65 for an undoped sample. The consistency of these three measurements on a large-grained homogeneous material is unambiguously supportive of C-substitution.

Susner, M. A., E-mail: susner.1@osu.edu; Bohnenstiehl, S. D.; Dregia, S. A.; Sumption, M. D.; Yang, Y.; Collings, E. W. [Department of Materials Science and Engineering, The Ohio State University, Columbus, Ohio 43210 (United States); Donovan, J. J. [Center for Advanced Materials Characterization in Oregon (CAMCOR), University of Oregon, Eugene, Oregon 97403 (United States)

2014-04-21T23:59:59.000Z

477

PROPAGATION OF SEISMIC WAVES THROUGH A SPATIO-TEMPORALLY FLUCTUATING MEDIUM: HOMOGENIZATION  

SciTech Connect

Measurements of seismic wave travel times at the photosphere of the Sun have enabled inferences of its interior structure and dynamics. In interpreting these measurements, the simplifying assumption that waves propagate through a temporally stationary medium is almost universally invoked. However, the Sun is in a constant state of evolution, on a broad range of spatio-temporal scales. At the zero-wavelength limit, i.e., when the wavelength is much shorter than the scale over which the medium varies, the WKBJ (ray) approximation may be applied. Here, we address the other asymptotic end of the spectrum, the infinite-wavelength limit, using the technique of homogenization. We apply homogenization to scenarios where waves are propagating through rapidly varying media (spatially and temporally), and derive effective models for the media. One consequence is that a scalar sound speed becomes a tensorial wave speed in the effective model and anisotropies can be induced depending on the nature of the perturbation. The second term in this asymptotic two-scale expansion, the so-called corrector, contains contributions due to higher-order scattering, leading to the decoherence of the wave field. This decoherence may be causally linked to the observed wave attenuation in the Sun. Although the examples we consider here consist of periodic arrays of perturbations to the background, homogenization may be extended to ergodic and stationary random media. This method may have broad implications for the manner in which we interpret seismic measurements in the Sun and for modeling the effects of granulation on the scattering of waves and distortion of normal-mode eigenfunctions.

Hanasoge, Shravan M. [Department of Geosciences, Princeton University, Princeton, NJ 08544 (United States); Gizon, Laurent [Max-Planck-Institut fuer Sonnensystemforschung, D-37191 Katlenburg-Lindau (Germany); Bal, Guillaume [Department of Applied and Physical Mathematics, Columbia University, New York, NY 10027 (United States)

2013-08-20T23:59:59.000Z

478

Micro-Scale Heterogeneity in Biogeochemical Uranium Cycling  

SciTech Connect

One method for the in situ remediation of uranium contaminated subsurface environments is the removal of highly soluble U(VI) from groundwater by microbial reduction to the sparingly soluble U(IV) mineral uraninite. Success of this remediation strategy will, in part, be determined by the extent and products of microbial reduction. In heterogeneous subsurface environments, microbial processes will likely yield a combination of U(IV) and U(VI) phases distributed throughout the soil matrix. Here, we use a combination of bulk X-ray absorption spectroscopy (XAS) and micro-focused XAS and X-ray diffraction to determine uranium speciation and distribution with sediment from a pilot-scale uranium remediation project located in Oak Ridge, TN.

Ginder-Vogel, M.; Wu, W.-M.; Kelly, S.; Criddle, C.S.; Carley, J.; Jardine, P.; Kemner, K.M.; Fendorf, S.

2009-06-04T23:59:59.000Z

479

Lattice vibration in homogeneously-mixed-valent systems of rare-earth materials  

Science Journals Connector (OSTI)

We investigate the essential feature of interplay between lattice vibration and valence fluctuation in the homogeneously-mixed-valent systems of rare-earth materials rigorously within simple models, paying special attention to studying the collective nature of excitations in lattice vibration as well as in valence fluctuation. We compare our results with experiments and find that the general features of the experiments of Sm0.75Y0.25S are well understood within the present model if we assume the characteristic energy of the valence fluctuation to be comparable to the phonon energy.

S. Ichinose and Y. Kuroda

1982-02-15T23:59:59.000Z

480

Hybrid combustion-premixed gasoline homogeneous charge ignited by injected diesel fuel-4-stroke cycle engines  

SciTech Connect

This paper describes the formation and testing of two hybrid combustion engines, wherein a premixed gasoline homogeneous charge was ignited by a small amount of injected diesel fuel under high compression ratio, by modifying open chamber and prechamber 4-stroke cycle diesel engines. It was found that the premixed gasoline was effective not only for decreasing the fuel consumption but also for reducing the smoke density both in the heavy and over-load regions. The effect of introducing a small amount N/sub 2/ gas for suppressing the diesel knock in the heavy load region also was examined.

Yonetani, H.; Okanishi, N.; Fukutani, I.; Watanabe, E.

1989-01-01T23:59:59.000Z

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.


481

Predictive Modeling of a Homogeneous Charge Compression Ignition (HCCI) Engine with EGR Fueled with Diesel  

Science Journals Connector (OSTI)

Homogeneous charge compression ignition (HCCI) combustion integrates features of both spark ignition (SI) and compression ignition (CI) engines, obtaining a promisingly high efficiency in a diesel engine with virtually almost no NOx and soot emissions. ... The objective of the model is to simulate fundamental engine results such as combustion pressure, heat-release rate, indicated mean pressure (IMEP), gas temperature, and exhaust gas emission from easily measured engine parameters. ... Gordon, P. B. The Design and Simulation of a 4 Stroke Engine; Society of Automotive Engineers: Warrendale, PA, 1999. ...

Miguel Torres García; Fco Jiménez-Espadafor Aguilar; Elisa Carvajal Trujillo; José Antonio Becerra Villanueva

2009-09-10T23:59:59.000Z

482

Fuel mixture stratification as a method for improving homogeneous charge compression ignition engine operation  

DOE Patents (OSTI)

A method for slowing the heat-release rate in homogeneous charge compression ignition ("HCCI") engines that allows operation without excessive knock at higher engine loads than are possible with conventional HCCI. This method comprises injecting a fuel charge in a manner that creates a stratified fuel charge in the engine cylinder to provide a range of fuel concentrations in the in-cylinder gases (typically with enough oxygen for complete combustion) using a fuel with two-stage ignition fuel having appropriate cool-flame chemistry so that regions of different fuel concentrations autoignite sequentially.

Dec, John E. (Livermore, CA); Sjoberg, Carl-Magnus G. (Livermore, CA)

2006-10-31T23:59:59.000Z

483

Effect of protein source and homogenization pressure on storage stability of retort processed dilute whey protein emulsions  

E-Print Network (OSTI)

Emulsions stabilized with acid whey or sweet whey were prepared using homogenization pressures of 30 or 90MPa. The emulsions were then canned and sterilized at 250F for 5 minutes. Emulsion stability, particle size and rheological properties were...

Bhatia, Sachin

2012-06-07T23:59:59.000Z

484

A Microfluidic System for the Continuous Recycling of Unmodified Homogeneous Palladium Catalysts through Liquid/Liquid Phase Separation  

E-Print Network (OSTI)

A prototype microflow system for the continuous recycling of homogeneous catalysts through liquid/liquid phase separation was developed and its effectiveness demonstrated in a challenging palladium-catalyzed hydroxylation ...

Li, Pengfei

485

Development of the temperature fields in an electric arc struck on a point electrode in a homogeneous gas stream  

Science Journals Connector (OSTI)

A study is made of the problem of a point electric source in a homogeneous gas stream and operating in the arc discharge regime. The development of an electric arc struck on a point cathode in a ... . The station...

A. B. Vatazhin

486

Pratt & Whtiney: Homogenous Metals,Inc. (HMI) Case Study: A Case STudy of the UTC Ace Operating System  

E-Print Network (OSTI)

Homogenous Metals Incorporated (HMI) is a pioneer in adopting and demonstrating value from United Technology Corporation's (UTC's) ACE operating system. ACE stands for Achieving Competitive Excellence. The first story is ...

Roth, George

2009-10-06T23:59:59.000Z

487

Hypersonic Buckshot: Astrophysical Jets as Heterogeneous Collimated Plasmoids  

E-Print Network (OSTI)

Herbig-Haro (HH) jets are commonly thought of as homogeneous beams of plasma traveling at hypersonic velocities. Structure within jet beams is often attributed to periodic or ``pulsed'' variations of conditions at the jet source. Simulations based on this scenario result in knots extending across the jet diameter. Observations and recent high energy density laboratory experiments shed new light on structures below this scale and indicate they may be important for understanding the fundamentals of jet dynamics. In this paper we offer an alternative to ``pulsed'' models of protostellar jets. Using direct numerical simulations we explore the possibility that jets are chains of sub-radial clumps propagating through a moving inter-clump medium. Our models explore an idealization of this scenario by injecting small ($r\\rho_{jet}$) spheres embedded in an otherwise smooth inter-clump jet flow. The spheres are initialized with velocities differing from the jet velocity by $\\sim15$%. We find the consequences of shiftin...

Yirak, Kristopher; Cunningham, Andrew J; Mitran, Sorin

2008-01-01T23:59:59.000Z

488

Effects of Tumor Microenvironment Heterogeneity on Nanoparticle Disposition and Efficacy in Breast Cancer Tumor Models  

Science Journals Connector (OSTI)

...microenvironment. The purpose of our study was to evaluate the role of heterogeneity of the...abnormal tumor microenvironment and has proved to selectively target tumor cells and reduce...have been approved and used clinically due to limited impacts on overall survival. Heterogeneity...

Gina Song; David B. Darr; Charlene M. Santos; Mark Ross; Alain Valdivia; Jamie L. Jordan; Bentley R. Midkiff; Stephanie Cohen; Nana Nikolaishvili-Feinberg; C. Ryan Miller; Teresa K. Tarrant; Arlin B. Rogers; Andrew C. Dudley; Charles M. Perou; William C. Zamboni

2014-12-01T23:59:59.000Z

489

Optimization of Wireless Access Point Placement in Realistic Urban Heterogeneous Networks  

E-Print Network (OSTI)

for irregular heterogeneous networks with hierarchical APs such as macro/micro base-stations, picoOptimization of Wireless Access Point Placement in Realistic Urban Heterogeneous Networks Yicheng network under a given user geographic distribution, and proposes an iterative method to optimize

Yu, Wei

490

Power-consumption minimization mechanism for heterogeneous multi-cell cellular network  

E-Print Network (OSTI)

Power-consumption minimization mechanism for heterogeneous multi-cell cellular network Chulhyun, yhchoi } @snu.ac.kr Power-consumption minimization mechanism for heterogeneous multi-cell cellular consumes large amount of energy, reduction of energy consumption in ICT attracts attention of research

491

Service-Oriented Heterogeneous Resource Sharing for Optimizing Service Latency in Mobile Cloud  

E-Print Network (OSTI)

Service-Oriented Heterogeneous Resource Sharing for Optimizing Service Latency in Mobile Cloud for mobile cloud applications and services. In this paper, we propose an architecture and mathematical frame- work for heterogeneous resource sharing based on the key idea of service-oriented utility functions

Mandayam, Narayan

492

Evidence for correlation of electrical resistivity and seismic velocity in heterogeneous near-surface materials  

E-Print Network (OSTI)

-surface materials. For both trends, the resistivity (r) and p-wave velocity (Vp) are related in the form Log10 r = m resistivity and seismic velocity in heterogeneous near-surface materials, Geophys. Res. Lett., 30(7), 1373Evidence for correlation of electrical resistivity and seismic velocity in heterogeneous near

Meju, Max

493

Towards an Integrated BPM Schema: Control Flow Heterogeneity of PNML and BPEL4WS  

E-Print Network (OSTI)

Towards an Integrated BPM Schema: Control Flow Heterogeneity of PNML and BPEL4WS Jan Mendling1 to identify extensions to the schema integration process in order to capture such specifics of BPM schemas. 1 Introduction Heterogeneity of Business Process Modelling (BPM) schemas is a notorious prob- lem for business

Zdun, Uwe

494

Dividing wall columns for heterogeneous azeotropic distillation Quang-Khoa Le1  

E-Print Network (OSTI)

Dividing wall columns for heterogeneous azeotropic distillation Quang-Khoa Le1 , Ivar J. Halvorsen2 of this work is to implement heterogeneous azeotropic distillation schemes in a dividing wall column (DWC distillation, Petlyuk arrangement, energy saving. 1. Introduction Distillation is one of the most energy

Skogestad, Sigurd

495

A novel framework for exploring 3-D FPGAs with heterogeneous interconnect fabric  

Science Journals Connector (OSTI)

A heterogeneous interconnect architecture can be a useful approach for the design of 3-D FPGAs. A methodology to investigate heterogeneous interconnection schemes for 3-D FPGAs under different 3-D fabrication technologies is proposed. Application of ... Keywords: 3-D integration, 3-D reconfigurable architectures, FPGAs, design framework, interconnection fabric

Kostas Siozios; Vasilis F. Pavlidis; Dimitrios Soudris

2012-03-01T23:59:59.000Z

496

ViperVM: a Runtime System for Parallel Functional High-Performance Computing on Heterogeneous Architectures  

E-Print Network (OSTI)

.henry@labri.fr Abstract The current trend in high-performance computing is to use het- erogeneous architectures (i-performance computer design has shifted from high-frequency multi-core architectures to heterogeneous archi- tecturesViperVM: a Runtime System for Parallel Functional High-Performance Computing on Heterogeneous

Paris-Sud XI, Université de

497

Optimal Microcell Deployment for Effective Mobile Device Energy Saving in Heterogeneous Networks  

E-Print Network (OSTI)

1 Optimal Microcell Deployment for Effective Mobile Device Energy Saving in Heterogeneous Networks--Heterogeneous network (HetNet) [1] is considered as an energy efficient system structure to alleviate the problemNet energy efficiency has been conducted. However, most of them only consider power consumption of Base

Boyer, Edmond

498

Plane wave solution for elastic wave scattering by a heterogeneous fracture  

E-Print Network (OSTI)

Plane wave solution for elastic wave scattering by a heterogeneous fracture Seiji Nakagawa,a) Kurt for computing the three-dimensional scattering of propagating elastic waves by a planar fracture with heterogeneous fracture compliance distribution is presented. This method is based upon the spatial Fourier

Santos, Juan

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Learning Organizational Roles in a Heterogeneous Multi-agent System M. V. Nagendra Prasad1  

E-Print Network (OSTI)

Learning Organizational Roles in a Heterogeneous Multi-agent System M. V. Nagendra Prasad1 , Victor of heterogeneous agents learn their organizational roles in negotiated search for mutually acceptable designs. We Amherst, MA 0l002 lander@bbtech.com Abstract This paper presents studies in learning a form of or

Massachusetts at Amherst, University of

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Mapping pipeline skeletons onto heterogeneous platforms Anne Benoit and Yves Robert  

E-Print Network (OSTI)

Mapping pipeline skeletons onto heterogeneous platforms Anne Benoit and Yves Robert January 2007 mapping of the application. In this paper, we discuss the mapping of pipeline skeletons onto different, Fully Heterogeneous platforms. We assume that a pipeline stage must be mapped on a single processor

Paris-Sud XI, Université de