These are representative sample records from Science.gov related to your search topic.
For comprehensive and current results, perform a real-time search at Science.gov.
1

Characterization of activation energy for flow in metallic glasses  

SciTech Connect

The molar volume (V{sub m}) scaled flow activation energy ({Delta}E), namely as the activation energy density {rho}{sub E}={Delta}E/V{sub m}, is proposed to describe the flow of metallic glasses. Based on the energy landscape, both the shear and bulk moduli are critical parameters accounting for the {rho}{sub E} of both homogeneous and inhomogeneous flows in metallic glasses. The expression of {rho}{sub E} is determined experimentally to be a simple expression of {rho}{sub E}=(10/11)G+(1/11)K. The energy density perspective depicts a realistic picture for the flow in metallic glasses and is suggestive for understanding the glass transition and deformation in metallic glasses.

Wang, J. Q.; Wang, W. H.; Liu, Y. H.; Bai, H. Y. [Institute of Physics, Chinese Academy of Sciences, Beijing 100190 (China)

2011-01-15

2

Energy Flow  

NSDL National Science Digital Library

The representation depicts the transfer of energy in a food chain. The resource is an interactive illustration of a farm scene depicting the flow of energy between the sun, a cornfield, a cow and a human through a food chain. To view the illustration, select Continue, then select Energy Flow button.

3

Determination of the Arrhenius Activation Energy Using a Temperature-Programmed Flow Reactor.  

ERIC Educational Resources Information Center

Describes a novel method for the determination of the Arrhenius activation energy, without prejudging the validity of the Arrhenius equation or the concept of activation energy. The method involves use of a temperature-programed flow reactor connected to a concentration detector. (JN)

Chan, Kit-ha C.; Tse, R. S.

1984-01-01

4

Neuroimaging and Neuroenergetics: Brain Activations as Information-Driven Reorganization of Energy Flows  

ERIC Educational Resources Information Center

There is increasing focus on the neurophysiological underpinnings of brain activations, giving birth to an emerging branch of neuroscience--neuroenergetics. However, no common definition of "brain activation" exists thus far. In this article, we define brain activation as the information-driven reorganization of energy flows in a population of…

Strelnikov, Kuzma

2010-01-01

5

Energy Efficient Thermal Management for Natural Gas Engine Aftertreatment via Active Flow Control  

Microsoft Academic Search

The project is focused on the development of an energy efficient aftertreatment system capable of reducing NOx and methane by 90% from lean-burn natural gas engines by applying active exhaust flow control. Compared to conventional passive flow-through reactors, the proposed scheme cuts supplemental energy by 50%-70%. The system consists of a Lean NOx Trap (LNT) system and an oxidation catalyst.

David K. Irick; Ke Nguyen; Vitacheslav Naoumov; Doug Ferguson

2006-01-01

6

Energy Efficient Thermal Management for Natural Gas Engine Aftertreatment via Active Flow Control  

Microsoft Academic Search

The project is focused on the development of an energy efficient aftertreatment system capable of reducing NOx and methane by 90% from lean-burn natural gas engines by applying active exhaust flow control. Compared to conventional passive flow-through reactors, the proposed scheme cuts supplemental energy by 50%-70%. The system consists of a Lean NOx Trap (LNT) system and an oxidation catalyst.

David K. Irick; Ke Nguyen; Vitacheslav Naoumov; Doug Ferguson

2005-01-01

7

Energy Efficient Thermal Management for Natural Gas Engine Aftertreatment via Active Flow Control  

SciTech Connect

The project is focused on the development of an energy efficient aftertreatment system capable of reducing NOx and methane by 90% from lean-burn natural gas engines by applying active exhaust flow control. Compared to conventional passive flow-through reactors, the proposed scheme cuts supplemental energy by 50%-70%. The system consists of a Lean NOx Trap (LNT) system and an oxidation catalyst. Through alternating flow control, a major amount of engine exhaust flows through a large portion of the LNT system in the absorption mode, while a small amount of exhaust goes through a small portion of the LNT system in the regeneration or desulfurization mode. By periodically reversing the exhaust gas flow through the oxidation catalyst, a higher temperature profile is maintained in the catalyst bed resulting in greater efficiency of the oxidation catalyst at lower exhaust temperatures. The project involves conceptual design, theoretical analysis, computer simulation, prototype fabrication, and empirical studies. This report details the progress during the first twelve months of the project. The primary activities have been to develop the bench flow reactor system, develop the computer simulation and modeling of the reverse-flow oxidation catalyst, install the engine into the test cell, and begin design of the LNT system.

David K. Irick; Ke Nguyen; Vitacheslav Naoumov; Doug Ferguson

2005-04-01

8

Energy Efficient Thermal Management for Natural Gas Engine Aftertreatment via Active Flow Control  

SciTech Connect

The project is focused on the development of an energy efficient aftertreatment system capable of reducing NOx and methane by 90% from lean-burn natural gas engines by applying active exhaust flow control. Compared to conventional passive flow-through reactors, the proposed scheme cuts supplemental energy by 50%-70%. The system consists of a Lean NOx Trap (LNT) system and an oxidation catalyst. Through alternating flow control, a major amount of engine exhaust flows through a large portion of the LNT system in the absorption mode, while a small amount of exhaust goes through a small portion of the LNT system in the regeneration or desulfurization mode. By periodically reversing the exhaust gas flow through the oxidation catalyst, a higher temperature profile is maintained in the catalyst bed resulting in greater efficiency of the oxidation catalyst at lower exhaust temperatures. The project involves conceptual design, theoretical analysis, computer simulation, prototype fabrication, and empirical studies. This report details the progress during the first twelve months of the project. The primary activities have been to develop the bench flow reactor system, develop the computer simulation and modeling of the reverse-flow oxidation catalyst, install the engine into the test cell, and begin design of the LNT system.

David K. Irick; Ke Nguyen; Vitacheslav Naoumov; Doug Ferguson

2006-04-01

9

ENERGY EFFICIENT THERMAL MANAGEMENT FOR NATURAL GAS ENGINE AFTERTREATMENT VIA ACTIVE FLOW CONTROL  

SciTech Connect

The project is focused on the development of an energy efficient aftertreatment system capable of reducing NOx and methane by 90% from lean-burn natural gas engines by applying active exhaust flow control. Compared to conventional passive flow-through reactors, the proposed scheme cuts supplemental energy by 50%-70%. The system consists of a Lean NOx Trap (LNT) system and an oxidation catalyst. Through alternating flow control, a major amount of engine exhaust flows through a large portion of the LNT system in the absorption mode, while a small amount of exhaust goes through a small portion of the LNT system in the regeneration or desulfurization mode. By periodically reversing the exhaust gas flow through the oxidation catalyst, a higher temperature profile is maintained in the catalyst bed resulting in greater efficiency of the oxidation catalyst at lower exhaust temperatures. The project involves conceptual design, theoretical analysis, computer simulation, prototype fabrication, and empirical studies. This report details the progress during the first twelve months of the project. The primary activities have been to develop the bench flow reactor system, develop the computer simulation and modeling of the reverse-flow oxidation catalyst, install the engine into the test cell, and begin design of the LNT system.

David K. Irick; Ke Nguyen

2004-04-01

10

Active flow control integrated diffuser (afcid) for increased energy efficiency in variable air volume systems  

NASA Astrophysics Data System (ADS)

Variable air volume (VAV) air terminals are designed to save energy by reducing airflow into a given space based on occupancy and required load. Systems are typically designed to operate at peak load, however as load is reduced, performance is compromised due to inadequate throw. As a result, fans are installed to adjust for the losses, negating many of the energy savings. Additionally flow is vectored by the use of vanes, a basic passive type of flow control. An experimental investigation was performed to study the application of flow control on that of a HVAC diffuser using synthetic jets distributed evenly along the diffuser edge parallel to the flow field. The study was conducted on a 1:3 scale typical office space (150 ft2), which included a simulated scale HVAC system supplied by compressed air. Two different jet blowing ratios were investigated for system loads of 60% and 90%. The flow field was established using hot wire anemometry and Particle Image Velocimetry (PIV). This study demonstrates the effectiveness of synthetic jet based active flow control at controlling airflow, showing ability to affect throw parameters for changing flow rates within the test chamber. Vectoring of up to 20% and improvement in jet spread of 200% was demonstrated. The use of such devices has the potential to improve air quality and air distribution in building while simultaneously lowering energy demands of HVAC systems.

Van Der Schijff, Hermanus P.

11

Active Lava Flows  

USGS Multimedia Gallery

View of the currently active flows on the pali, east of Royal Gardens subdivision. The corresponding thermal image highlights the active flow area clearly. The active flows are traveling down the east margin of the Thanksgiving Eve Breakout (TEB) flow field. The flows are being fed by a lengthening ...

12

Heat and Mass Transfer in Unsteady Rotating Fluid Flow with Binary Chemical Reaction and Activation Energy  

PubMed Central

In this study, the Spectral Relaxation Method (SRM) is used to solve the coupled highly nonlinear system of partial differential equations due to an unsteady flow over a stretching surface in an incompressible rotating viscous fluid in presence of binary chemical reaction and Arrhenius activation energy. The velocity, temperature and concentration distributions as well as the skin-friction, heat and mass transfer coefficients have been obtained and discussed for various physical parametric values. The numerical results obtained by (SRM) are then presented graphically and discussed to highlight the physical implications of the simulations. PMID:25250830

Awad, Faiz G.; Motsa, Sandile; Khumalo, Melusi

2014-01-01

13

Energy Flow  

NSDL National Science Digital Library

Through the process of photosynthesis, plants harness the sun's energy and in so doing make many forms of life, including human life, possible. What path does this energy follow, and how is it transferred from one type of organism to another? In this feature, adapted from Interactive NOVA: Earth, learn why 400 pounds of corn can't be converted into a 400-pound cow.

2003-12-26

14

Active Lava Flow  

USGS Multimedia Gallery

Flows continue to be active south of the Kalapana access road, heading in a generally eastward direction. These breakouts were active just a few hundred meters east of the County lava viewing area....

15

Neuroimaging and neuroenergetics: Brain activations as information-driven reorganization of energy flows  

E-print Network

Neuroimaging and neuroenergetics: Brain activations as information-driven reorganization of energy 25 January 2010 Keywords: Neuroimaging Neuroenergetics Brain activation Cortical response Deviance detection a b s t r a c t There is increasing focus on the neurophysiological underpinnings of brain

16

Active Lava Flow  

USGS Multimedia Gallery

The currently active flows on the pali continue to chip away at the few remaining streets in the beleaguered Royal Gardens subdivision. Those visible here are pretty much all that's left, with the exception of one small kipuka out of sight to the right....

17

Dynamo dominated accretion and energy flow: The mechanism of active galactic nuclei  

SciTech Connect

An explanation of the magnetic fields of the universe, the central mass concentration of galaxies, the massive black hole of every galaxy, and the AGN phenomena has been an elusive goal. The authors suggest here the outlines of such a theoretical understanding and point out where the physical understanding is missing. They believe there is an imperative to the sequence of mass flow and hence energy flow in the collapse of a galactic mass starting from the first non-linearity appearing in structure formation following decoupling. This first non-linearity of a two to one density fluctuation, the Lyman-{alpha} clouds, ultimately leads to the emission spectra of the phenomenon of AGN, quasars, blazars, etc. The over-arching physical principle is the various mechanisms for the transport of angular momentum. They believe they have now understood the new physics of two of these mechanisms that have previously been illusive and as a consequence they impose strong constraints on the initial conditions of the mechanisms for the subsequent emission of the gravitational binding energy. The new phenomena described are: (1) the Rossby vortex mechanism of the accretion disk {alpha}-viscosity, and (2) the mechanism of the {alpha}-{Omega} dynamo in the accretion disk. The Rossby vortex mechanism leads to a prediction of the black hole mass and rate of energy release and the {alpha}-{Omega} dynamo leads to the generation of the magnetic flux of the galaxy (and the far greater magnetic flux of clusters) and separately explains the primary flux of energy emission as force-free magnetic energy density. This magnetic flux and magnetic energy density separately are the necessary consequence of the saturation of a dynamo created by the accretion disk with a gain greater than unity.

Colgate, S.A.; Li, H.

1998-12-31

18

Activation Energy for Mobility of Dyes and Proteins in Polymer Solutions: From Diffusion of Single Particles to Macroscale Flow  

NASA Astrophysics Data System (ADS)

We measure the activation energy Ea for the diffusion of molecular probes (dyes and proteins of radii from 0.52 to 6.9 nm) and for macroscopic flow in a model complex liquid—aqueous solutions of polyethylene glycol. We cover a broad range of polymer molecular weights, concentrations, and temperatures. Fluorescence correlation spectroscopy and rheometry experiments reveal a relationship between the excess of the activation energy in polymer solutions over the one in pure solvent ?Ea and simple parameters describing the structure of the system: probe radius, polymer hydrodynamic radius, and correlation length. ?Ea varies by more than an order of magnitude in the investigated systems (in the range of ca. 1-15kJ/mol) and for probes significantly larger than the polymer hydrodynamic radius approaches the value measured for macroscopic flow. We develop an explicit formula describing the smooth transition of ?Ea from the diffusion of molecular probes to macroscopic flow. This formula is a reference for the quantitative analysis of specific interactions of moving nano-objects with their environment as well as active transport. For instance, the power developed by a molecular motor moving at constant velocity u is proportional to u2exp?(Ea/RT).

Soza?ski, Krzysztof; Wi?niewska, Agnieszka; Kalwarczyk, Tomasz; Ho?yst, Robert

2013-11-01

19

Thermally Activated Energy and Flux-flow Hall Effect of Fe1+y(Te1+xSx)z  

SciTech Connect

Thermally activated flux flow (TAFF) and flux-flow Hall effect (FFHE) of Fe(Te,S) single crystal in the mixed state are studied in magnetic fields up to 35 T. Thermally activated energy (TAE) is analyzed using conventional Arrhenius relation and modified TAFF theory which is closer to experimental results. The results indicate that there is a crossover from single-vortex pinning region to collective creep pinning region with increasing magnetic field. The temperature dependence of TAE is different for H {parallel} ab and H {parallel} c. On the other hand, the analysis of FFHE in the mixed state indicates that there is no Hall sign reversal. We also observe scaling behavior |{rho}{sub xy}(H)|=A{rho}{sub xx}(H){sup {beta}}.

Petrovic, C.; Lei, H.; Hu, R.; Choi, E.S.

2010-10-19

20

Thermally activated energy and flux flow Hall effect in Fe1+yTe1-xSx  

SciTech Connect

Thermally activated flux flow (TAFF) and flux-flow Hall effect (FFHE) of Fe(Te,S) single crystal in the mixed state are studied in magnetic fields up to 35 T. Thermally activated energy (TAE) is analyzed using conventional Arrhenius relation and modified TAFF theory which is closer to experimental results. The results indicate that there is a crossover from single-vortex pinning region to collective creep pinning region with increasing magnetic field. The temperature dependence of TAE is different for H?ab and H?c . On the other hand, the analysis of FFHE in the mixed state indicates that there is no Hall sign reversal. We also observe scaling behavior ? ?{sub xy} (H)? =A?{sub xx} (H){sup ?} .

Lei, Heichang; Hu, Rongwei; Choi, E.S.; Petrovic, Cedomir

2010-01-01

21

NEED Project: Energy Flows  

NSDL National Science Digital Library

This teaching module for Grades 6-8 introduces energy transfers and transformations and the flow of energy through systems. The core of the lesson is its 14 custom graphics developed by the NEED project to show energy flow in real-life systems, from start to finish. The graphics (much easier to digest than Sankey diagrams) were designed to help students understand that energy can be transferred and converted into other forms, but never destroyed. It includes a unique "Energy Flow Card" game, where students engage in creative dramatics to act out energy transformations by connecting the cards correctly. The NEED Project is a national initiative to bring innovative curriculum materials in energy education to teachers and learners from the primary grades through college.

22

US energy flow - 1984  

Microsoft Academic Search

The 1984 energy flow diagram for the USA has been constructed using Department of Energy data. It is a convenient graphical device to show supply and demand as well as the size of end-use sectors. A 4% increase in overall energy consumption represented a reversal in a downward trend started in 1979. All indicators pointed to more healthy industrial and

C. K. Briggs; I. Y. Borg

1985-01-01

23

A simple experiment to determine the activation energy of the viscous flow of polymer solutions using a glass capillary viscometer  

NASA Astrophysics Data System (ADS)

A simple viscometry experiment undertaken by an undergraduate polymer class as a research project is described. Viscosity is a measure of a fluid's resistance to flow and is affected by several factors, such as concentration and temperature. In this experiment, the viscosities of polyvinylpyrrolidone solutions (a polymeric material) of different concentrations were prepared in water and measured at various temperatures. The solution viscosity was found to increase gradually with increasing concentration up to ?5 mass%, with a dramatic increase after this. The calculated viscosity of water at different temperatures was comparable to reported values. The activation energy of viscous flow (Ea) of the different solutions was calculated and followed a similar trend as that for the viscosities of solutions of various concentrations. This experiment allowed students to better understand and explain the behaviour of macromolecules with respect to changing concentration and temperature. Furthermore, students correlated the viscosity and Ea results to understand how an increase in the concentration of a polymer solution resulted in increased entanglement of the polymer chains, consequently leading to an increase in viscosity and an increase in the activation energy of viscous flow. This experiment is safe, low cost, simple and requires only readily available apparatus.

Rohindra, D. R.; Lata, R. A.; Coll, R. K.

2012-09-01

24

The Flow of Energy  

Microsoft Academic Search

In this paper, the flow of energy in materials is presented as mechanical waves with a distinct velocity or speed of transition. This speed of transition came about through the observations of cold fusion experiments, i.e., Low Energy Nuclear Reactions (LENR) and superconductor gravity experiments, both assumed speculative by mainstream science. In consideration of superconductor junctions, the LENR experiments have

F. Znidarsic; G. A. Robertson

2011-01-01

25

Estimated International Energy Flows 2007  

NSDL National Science Digital Library

This Energy Flow Charts website is a set of energy Sankey diagrams or flow charts for 136 countries constructed from data maintained by the International Energy Agency (IEA) and reflects the energy use patterns for 2007.

Clara Smith

26

Food Web and Energy Flow  

NSDL National Science Digital Library

This chapter discusses the concept of a food web and energy flow. Its activities will assist students in defining and constructing an energy pyramid. These activities can be incorporated into lessons which teach students how to create a food web and and identify the interdependencies within that habitat. Students will learn how to identify and illustrate parts of the water cycle, the carbon-oxygen cycle, and the nitrogen cycle. This section also offers students the tools to demonstrate active knowledge of conservation measures.

Janet R. Galle

2005-01-01

27

The Flow of Energy  

NASA Astrophysics Data System (ADS)

In this paper, the flow of energy in materials is presented as mechanical waves with a distinct velocity or speed of transition. This speed of transition came about through the observations of cold fusion experiments, i.e., Low Energy Nuclear Reactions (LENR) and superconductor gravity experiments, both assumed speculative by mainstream science. In consideration of superconductor junctions, the LENR experiments have a similar speed of transition, which seems to imply that the reactions in the LENR experiment are discrete quantized reactions (energy - burst vs. continuous). Here an attempt is made to quantify this new condition as it applies to electrons; toward the progression of quantized energy flows (discrete energy burst) as a new source of clean energy and force mechanisms (i.e, propulsion).

Znidarsic, F.; Robertson, G. A.

28

Energy Flow Energy Flow Energy Flow A.Ukleja, T.Tymieniecka, I.Skillicorn 1 Azimuthal asymmetry  

E-print Network

Energy Flow Energy Flow Energy Flow A.Ukleja, T.Tymieniecka, I.Skillicorn 1 Azimuthal asymmetry using energy flow method Azimuthal angle distribution at Q2 >100 GeV2 Energy flow method.Ukleja on behalf of the ZEUS Collaboration #12; Energy Flow Energy Flow Energy Flow A.Ukleja, T.Tymieniecka, I

29

Radiant Energy Flow  

NSDL National Science Digital Library

How does energy flow in and out of our atmosphere? Explore how solar and infrared radiation enters and exits the atmosphere with an interactive model. Control the amounts of carbon dioxide and clouds present in the model and learn how these factors can influence global temperature. Record results using snapshots of the model in the virtual lab notebook where you can annotate your observations.

2012-07-19

30

Global Energy Flows  

NSDL National Science Digital Library

In this activity, students analyze data detailing global energy sources and sinks (uses) and construct a diagram to show the relative scale and the connections between them. Discussions of scale; historical, socio-environmental, and geographic variation in this data; and implications for future energy use are included.

Great Lakes Bioenergy Research Center

31

Active p?hoehoe flow  

USGS Multimedia Gallery

The active front of a p?hoehoe flow near the intersection of Pikake and Warrior Street, in the Royal Gardens subdivision. The road in the lower portion of the photo is the last remaining piece of Pikake Street. ...

32

2007 Estimated International Energy Flows  

SciTech Connect

An energy flow chart or 'atlas' for 136 countries has been constructed from data maintained by the International Energy Agency (IEA) and estimates of energy use patterns for the year 2007. Approximately 490 exajoules (460 quadrillion BTU) of primary energy are used in aggregate by these countries each year. While the basic structure of the energy system is consistent from country to country, patterns of resource use and consumption vary. Energy can be visualized as it flows from resources (i.e. coal, petroleum, natural gas) through transformations such as electricity generation to end uses (i.e. residential, commercial, industrial, transportation). These flow patterns are visualized in this atlas of 136 country-level energy flow charts.

Smith, C A; Belles, R D; Simon, A J

2011-03-10

33

Industrial energy-flow management  

Microsoft Academic Search

Deregulation of the energy market has created new opportunities for the development of new energy-management methods based on energy assets, risk management, energy efficiency and sustainable development. Industrial energy-flow management in pharmaceutical systems, with a responsible approach to sustainable development, is a complex task. For this reason, an energy-information centre, with over 14,000 online measured data\\/nodes, was implemented. This paper

Marko Lampret; Venceslav Bukovec; Andrej Paternost; Srecko Krizman; Vito Lojk; Iztok Golobic

2009-01-01

34

Industrial energy-flow management  

Microsoft Academic Search

Deregulation of the energy market has created new opportunities for the development of new energy-management methods based on energy assets, risk management, energy efficiency and sustainable development. Industrial energy-flow management in pharmaceutical systems, with a responsible approach to sustainable development, is a complex task. For this reason, an energy-information centre, with over 14,000 online measured data\\/nodes, was implemented. This paper

Marko Lampret; Venceslav Bukovec; Andrej Paternost; Srecko Krizman; Vito Lojk; Iztok Golobic

2007-01-01

35

California energy flow in 1989  

NASA Astrophysics Data System (ADS)

California's energy use showed a modest increase (2.2 percent) in 1989 over 1988 which was in keeping with the steady increase in population that the state has experienced annually during the decade. All end-use sectors (residential, commercial, industrial, transportation, etc.) contributed to the growth. The larger demand was met by increased imports of all major fuels. Only electrical imports remained close to 1988 levels, in part due to increased output from Diablo Canyon nuclear plant whose performance exceeded expectations. California's per capita energy consumption has traditionally been below the national average due to the relatively benign climate associated with its centers of population. The largest single use for energy in the state was for transportation, which overtook industrial usage in the 60's. Use of highway fuels continued to grow and reached all time highs in 1989. Highway congestion, a major problem and concern in the state, is anticipated to grow as the number of licensed drivers increases; in 1989 the increase was 3.4 percent. Output from the The Geysers Geothermal fields, the largest in the world, continued to falter as the steam output fell. Nonetheless new resources at the Coso Geothermal Resource Area and at the Wendel Geothermal field came on line during the year, and other geothermal areas were under active development. Novel sources of renewable energy (solar, wind, etc.) grew; however, collectively they made only a small contribution to the overall energy supply. Cogenerated electricity sold to the utilities by small power producers inexplicably fell in 1989 although estimates of the total capacity available rose. Energy flow diagrams illustrate energy sources and energy consumption.

Borg, I. Y.; Briggs, C. K.

1991-02-01

36

Boeing active flow control system  

NASA Astrophysics Data System (ADS)

The Boeing Active Flow Control (AFC) System (BAFCS) is a DARPA sponsored program to develop AFC technology to achieve a significant increase in payload for the V-22 tiltrotor vehicle. The program includes Computational Fluid Dynamics analysis, wind tunnel testing and development of smart materials based AFC actuators. This paper will provide an overview of the program and its interrelationships, as well as concentrating on the development of the AFC actuators.

Jacot, A. Dean; Calkins, Frederick T.

2000-06-01

37

Activation Energy  

NASA Technical Reports Server (NTRS)

Teaming is so common in today's project management environment that most of us assume it comes naturally. We further assume that when presented with meaningful and challenging work, project teams will naturally engage in productive activity to complete their tasks. This assumption is expressed in the simple (but false) equation: Team + Work = Teamwork. Although this equation appears simple and straightforward, it is far from true for most project organizations whose reality is a complex web of institutional norms based on individual achievement and rewards. This is illustrated by the very first successful team experience from my early Air Force career. As a young lieutenant, I was sent to Squadron Officer School, which was the first in the series of Air Force professional military education courses I was required to complete during my career. We were immediately formed into teams of twelve officers. Much of the course featured competition between these teams. As the most junior member of my team, I quickly observed the tremendous pressure to show individual leadership capability. At one point early in the course, almost everyone in our group was vying to become the team leader. This conflict was so intense that it caused us to fail miserably in our first outdoor team building exercise. We spent so much time fighting over leadership that we were unable to complete any of the events on the outdoor obstacle course. This complete lack of success was so disheartening to me that I gave our team little hope for future success. What followed was a very intense period of bickering, conflict, and even shouting matches as our dysfunctional team tried to cope with our early failures and find some way to succeed. British physician and researcher Wilfred Bion (Experiences in Groups, 1961) discovered that there are powerful psychological forces inherent in all groups that divert from accomplishing their primary tasks. To overcome these restraining forces and use the potential power of the team, greater emphasis must be placed on establishing and maintaining group cohesiveness. This relationship is expressed in the revised (true) mathematical equation: Team + Work (on the Team) = Teamwork.

Gadeken, Owen

2002-01-01

38

High energy density redox flow device  

DOEpatents

Redox flow devices are described in which at least one of the positive electrode or negative electrode-active materials is a semi-solid or is a condensed ion-storing electroactive material, and in which at least one of the electrode-active materials is transported to and from an assembly at which the electrochemical reaction occurs, producing electrical energy. The electronic conductivity of the semi-solid is increased by the addition of conductive particles to suspensions and/or via the surface modification of the solid in semi-solids (e.g., by coating the solid with a more electron conductive coating material to increase the power of the device). High energy density and high power redox flow devices are disclosed. The redox flow devices described herein can also include one or more inventive design features. In addition, inventive chemistries for use in redox flow devices are also described.

Chiang, Yet-Ming; Carter, W. Craig; Ho, Bryan Y; Duduta, Mihai; Limthongkul, Pimpa

2014-05-13

39

Active Flow Control Activities at NASA Langley  

NASA Technical Reports Server (NTRS)

NASA Langley continues to aggressively investigate the potential advantages of active flow control over more traditional aerodynamic techniques. This paper provides an update to a previous paper and describes both the progress in the various research areas and the significant changes in the NASA research programs. The goals of the topics presented are focused on advancing the state of knowledge and understanding of controllable fundamental mechanisms in fluids as well as to address engineering challenges. An organizational view of current research activities at NASA Langley in active flow control as supported by several projects is presented. On-center research as well as NASA Langley funded contracts and grants are discussed at a relatively high level. The products of this research are to be demonstrated either in bench-top experiments, wind-tunnel investigations, or in flight as part of the fundamental NASA R&D program and then transferred to more applied research programs within NASA, DOD, and U.S. industry.

Anders, Scott G.; Sellers, William L., III; Washburn, Anthony E.

2004-01-01

40

Carbon Energy Flows Belowground  

Technology Transfer Automated Retrieval System (TEKTRAN)

Plants use photosynthesis to convert carbon dioxide in the atmosphere and energy from sunlight into energy-containing, carbon-based foodstuffs (i.e. carbohydrates such as sugars and starches) that provide the building blocks for all life on Earth. Without photosynthesis, sunlight would not be a goo...

41

Productivity & Energy Flow  

E-print Network

The feeding activities of a few keystone species may control the structure of communities Know Paine's Starfish Mutualists can act as keystone species Summary (continued) Terrestrial productivity is generally the feeding relationships in a community Indirect interactions between species are fundamental to communities

Mitchell, Randall J.

42

Object Flow Definition for Refined Activity Diagrams  

Microsoft Academic Search

Activity diagrams are a well-known means to model the control flow of system behavior. Their expressiveness can be enhanced\\u000a by using their object flow notation. In addition, we refine activities by pairs of pre- and post-conditions formulated by\\u000a interrelated object diagrams. To define a clear semantics for refined activity diagrams with object flow, we use a graph transformation\\u000a approach. Control

Stefan Jurack; Leen Lambers; Katharina Mehner; Gabriele Taentzer; Gerd Wierse

2009-01-01

43

Single-Phase Inverter Control Techniques for Interfacing Renewable Energy Sources With Microgrid—Part I: Parallel-Connected Inverter Topology With Active and Reactive Power Flow Control Along With Grid Current Shaping  

Microsoft Academic Search

In this paper, a novel current control technique is proposed to control both active and reactive power flow from a renewable energy source feeding a microgrid system through a single-phase parallel-connected inverter. The parallel-connected inverter ensures active and reactive power flow from the grid with low-current total harmonic distortion even in the presence of non- linear load. A p-q theory-based

Souvik Dasgupta; Sanjib Kumar Sahoo; Sanjib Kumar Panda

2011-01-01

44

Active combustion flow modulation valve  

DOEpatents

A flow modulation valve has a slidably translating hollow armature with at least one energizable coil wound around and fixably attached to the hollow armature. The energizable coil or coils are influenced by at least one permanent magnet surrounding the hollow armature and supported by an outer casing. Lorentz forces on the energizable coils which are translated to the hollow armature, increase or decrease the flow area to provide flow throttling action. The extent of hollow armature translation depends on the value of current supplied and the direction of translation depends on the direction of current flow. The compact nature of the flow modulation valve combined with the high forces afforded by the actuator design provide a flow modulation valve which is highly responsive to high-rate input control signals.

Hensel, John Peter; Black, Nathaniel; Thorton, Jimmy Dean; Vipperman, Jeffrey Stuart; Lambeth, David N; Clark, William W

2013-09-24

45

Energy Flow in the Atmosphere  

NSDL National Science Digital Library

This textbook chapter introduces the concepts of static and dynamic equilibrium, and discusses contemporary climate change. The greenhouse effect is presented in a discussion of Mars, Venus and Earth, the "Goldilocks" planet. Two investigations support the chapter. The resource includes links to current news articles, and a suite of pre- and post-unit assessments. A teacher's guide supports classroom use. This is the sixth chapter in the unit, Energy Flow, exploring the flow of energy through the atmosphere, oceans, land, and living things over short and long timescales. The resource is part of Global System Science (GSS), an interdisciplinary course for high school students that emphasizes how scientists from a wide variety of fields work together to understand significant problems of global impact.

46

A simple experiment to determine the activation energy of the viscous flow of polymer solutions using a glass capillary viscometer  

Microsoft Academic Search

A simple viscometry experiment undertaken by an undergraduate polymer class as a research project is described. Viscosity is a measure of a fluid's resistance to flow and is affected by several factors, such as concentration and temperature. In this experiment, the viscosities of polyvinylpyrrolidone solutions (a polymeric material) of different concentrations were prepared in water and measured at various temperatures.

D R Rohindra; R A Lata; R K Coll

2012-01-01

47

Analysis of Flow Cytometry DNA Damage Response Protein Activation Kinetics Following X-rays and High Energy Iron Nuclei Exposure  

SciTech Connect

We developed a mathematical method to analyze flow cytometry data to describe the kinetics of {gamma}H2AX and pATF2 phosphorylations ensuing various qualities of low dose radiation in normal human fibroblast cells. Previously reported flow cytometry kinetic results for these DSB repair phospho-proteins revealed that distributions of intensity were highly skewed, severely limiting the detection of differences in the very low dose range. Distributional analysis reveals significant differences between control and low dose samples when distributions are compared using the Kolmogorov-Smirnov test. Radiation quality differences are found in the distribution shapes and when a nonlinear model is used to relate dose and time to the decay of the mean ratio of phosphoprotein intensities of irradiated samples to controls. We analyzed cell cycle phase and radiation quality dependent characteristic repair times and residual phospho-protein levels with these methods. Characteristic repair times for {gamma}H2AX were higher following Fe nuclei as compared to X-rays in G1 cells (4.5 {+-} 0.46 h vs 3.26 {+-} 0.76 h, respectively), and in S/G2 cells (5.51 {+-} 2.94 h vs 2.87 {+-} 0.45 h, respectively). The RBE in G1 cells for Fe nuclei relative to X-rays for {gamma}H2AX was 2.05 {+-} 0.61 and 5.02 {+-} 3.47, at 2 h and 24-h postirradiation, respectively. For pATF2, a saturation effect is observed with reduced expression at high doses, especially for Fe nuclei, with much slower characteristic repair times (>7 h) compared to X-rays. RBEs for pATF2 were 0.66 {+-} 0.13 and 1.66 {+-} 0.46 at 2 h and 24 h, respectively. Significant differences in {gamma}H2AX and pATF2 levels comparing irradiated samples to control were noted even at the lowest dose analyzed (0.05 Gy) using these methods of analysis. These results reveal that mathematical models can be applied to flow cytometry data to uncover important and subtle differences following exposure to various qualities of low dose radiation.

Universities Space Research Association; Chappell, Lori J.; Whalen, Mary K.; Gurai, Sheena; Ponomarev, Artem; Cucinotta, Francis A.; Pluth, Janice M.

2010-12-15

48

Go with the Energy Flow  

NSDL National Science Digital Library

Students learn about energy and nutrient flow in various biosphere climates and environments. They learn about herbivores, carnivores, omnivores, food chains and food webs, seeing the interdependence between producers, consumers and decomposers. Students are introduced to the roles of the hydrologic (water), carbon, and nitrogen cycles in sustaining the worlds' ecosystems so living organisms survive. This lesson is part of a series of six lessons in which students use their growing understanding of various environments and the engineering design process, to design and create their own model biodome ecosystems.

Integrated Teaching and Learning Program,

49

Thermal and Visible Imagery: Active Flows  

USGS Multimedia Gallery

This comparison of thermal images over the coastal plain shows the advancement of the active flows over the past week. At the top, a normal photograph from April 15 gives reference. The middle frame, from April 15, shows that the flows were approaching the bottom of the pali last week. In the bottom...

50

Energy Flow through a Paper Ecosystem.  

ERIC Educational Resources Information Center

Presented is an exercise for high school students which illustrates the principle and practice of measuring energy flow through a community. Included are worksheets, instructions, a flow diagram, and a list of ecosystem parameters. (Author/CW)

Aston, T. J.

1988-01-01

51

Activation parameters of flow through battery separators  

NASA Technical Reports Server (NTRS)

Studies of the hydrodynamic flow of water and 45 percent potassium hydroxide (KOH) solution through a microporous and an ion exchange separator are described. The permeability values are interpreted in terms of a pseudoactivation process. The enthalpy of activation deltaH* and the entropy of activation deltaS* were estimated from Eyring's rate equation.

Blokhra, R. L.

1983-01-01

52

Energy assessment: physical activity  

Technology Transfer Automated Retrieval System (TEKTRAN)

Physical activity is an important component of total energy expenditure, contributing to energy intake needs; it also provides certain health benefits. This review chapter provides state-of-the-art information to researchers and clinicians who are interested in developing research studies or interv...

53

Transitioning Active Flow Control to Applications  

NASA Technical Reports Server (NTRS)

Active Flow Control Programs at NASA, the U.S. Air Force, and DARPA have been initiated with the goals of obtaining revolutionary advances in aerodynamic performance and maneuvering compared to conventional approaches. These programs envision the use of actuators, sensors, and controllers on applications such as aircraft wings/tails, engine nacelles, internal ducts, nozzles, projectiles, weapons bays, and hydrodynamic vehicles. Anticipated benefits of flow control include reduced weight, part count, and operating cost and reduced fuel burn (and emissions), noise and enhanced safety if the sensors serve a dual role of flow control and health monitoring. To get from the bench-top or laboratory test to adaptive distributed control systems on realistic applications, reliable validated design tools are needed in addition to sub- and large-scale wind-tunnel and flight experiments. This paper will focus on the development of tools for active flow control applications.

Joslin, Ronald D.; Horta, Lucas G.; Chen, Fang-Jenq

1999-01-01

54

Magnetic energy flow in the solar wind.  

NASA Technical Reports Server (NTRS)

Discussion of the effect of rotation (tangential flow) of the solar wind on the conclusions of Whang (1971) suggesting an increase in the solar wind velocity due to the conversion of magnetic energy to kinetic energy. It is shown that the effect of the rotation of the sun on the magnetic energy flow results in most of the magnetic energy being transported by magnetic shear stress near the sun.

Modisette, J. L.

1972-01-01

55

Flow energy harvesting -- another application of the biomimetic flapping foils  

NASA Astrophysics Data System (ADS)

Imitating fish fins and insect wings, flapping foils are usually used for biomimetic propulsion. Theoretical studies and experiments have demonstrated that through specific combinations of heaving and pitching motions, these foils can also extract energy from incoming wind or current. Compared with conventional flow energy harvesting devices based upon rotating turbines, this novel design promises mitigated impact upon the environment. To achieve the required motions, existing studies focus on hydrodynamic mode coupling, in which a periodic pitching motion is activated and a heaving motion is then generated by the oscillating lifting force. Energy extraction is achieved through a damper in the heaving direction (representing the generator). This design involves a complicated control and activation system. In addition, there is always the possibility that the energy required to activate the system exceeds the energy recovered by the generator. We have discovered that a much simpler device without activation, a 2DOF foil mounted on a rotational spring and a damper undergoing flow-induced motions can achieve stable flow energy harvesting. Using Navier-Stokes simulations we predicted different behaviors of the system during flow-induced vibrations and identified the specific requirements to achieve controllable periodic motions essential for stable energy harvesting. The energy harvesting capacity and efficiency were also determined.

Zhu, Qiang; Peng, Zhangli

2009-11-01

56

Flow systematics from SIS to SPS energies  

E-print Network

The various flow phenomena observed at energies between 50 AMeV and 160 AGeV are reviewed. I first define three types of flow: directed flow and elliptic flow, which are the two first Fourier components of the azimuthal distribution in non-central collisions; radial flow, which is deduced from an analysis of transverse momentum spectra in central collisions. Then, I review the observations of directed flow and elliptic flow, with emphasis on recent results. I discuss their dependence on various parameters: global geometry (impact parameter, mass numbers of colliding nuclei and bombarding energy) and individual observables (rapidity, transverse momentum and particle type). Finally, I explain how azimuthal distributions can be measured experimentally.

Jean-Yves Ollitrault

1998-02-12

57

Introduction to Alternative and Renewable Energy: Energy Flow Analytics  

NSDL National Science Digital Library

This module is intended for use in a college-level introductory course in alternative and renewable energy. The document covers energy flow analytics. Several useful graphics are included which provide data on energy flow and consumption as well as US transportation consumption. This module may be downloaded in PDF file format.

58

Science Activities in Energy: Chemical Energy.  

ERIC Educational Resources Information Center

Presented is a science activities in energy package which includes 15 activities relating to chemical energy. Activities are simple, concrete experiments for fourth, fifth and sixth grades which illustrate principles and problems relating to energy. Each activity is outlined on a single card which is introduced by a question. A teacher's…

Oak Ridge Associated Universities, TN.

59

Energy Flow: Flow Charts Illustrating United States Energy Resources and Usage, from Lawrence Livermore National Laboratory  

DOE Data Explorer

Decision makers have long recognized the importance of visualizing energy and material flows in a way that distinguishes between resources, transformations and services. Research priorities can be defined in terms of changes to the flows, and the consequences of policy or technology shifts can be traced both upstream and downstream. The usefulness of this top-down view is limited by the level of detail that can be conveyed in a single image. We use two techniques to balance information content with readability. First we employe visualization techniques, such as those embodied in the energy Sankey diagram below (Figure 1), to display both qualitative (relative line weight) and quantitative (listed values) information in a reader-friendly package. The second method is to augment static images with dynamic, scalable digital content containing multiple layers (e.g. energy, carbon and economic data). This transitions the audience from that of a passive reader to an active user of the information. When used in conjunction these approaches enable relatively large, interconnected processes to be described and analyzed efficiently. [copied from the description at http://en.openei.org/wiki/LLNL_Energy_Flow_Charts#cite_note-1

60

Changing Conceptions of Activation Energy.  

ERIC Educational Resources Information Center

Provides background material which relates to the concept of activation energy, fundamental in the study of chemical kinetics. Compares the related concepts of the Arrhenius activation energy, the activation energy at absolute zero, the enthalpy of activation, and the threshold energy. (CS)

Pacey, Philip D.

1981-01-01

61

Thermal energy scavenger (flow control)  

SciTech Connect

A thermal energy scavenger assembly is described including a plurality of temperature-sensitive wires made of material which exhibits shape memory due to a thermoelastic, martensitic phase transformation. The wires are placed in tension between fixed and movable plates which are, in turn, supported by a pair of wheels which are rotatably supported by a housing for rotation about a central axis. A pair of upper and lower cams are fixed to the housing and cam followers react with the respective cams. Each cam transmits forces through a pair of hydraulic pistons. One of the pistons is connected to a movable plate to which one end of the wires are connected whereby a stress is applied to the wires to strain the wires during a first phase and whereby the cam responds to the unstraining of the wires during a second phase. A housing defines fluid compartments through which hot and cold fluid passes and flows radially through the wires whereby the wires become unstrained and shorten in length when subjected to the hot fluid for causing a reaction between the cam followers and the cams to effect rotation of the wheels about the central axis of the assembly, which rotation of the wheels is extracted through beveled gearing. The wires are grouped into a plurality of independent modules with each module having a movable plate, a fixed plate and the associated hydraulic pistons and cam follower. The hydraulic pistons and cam follower of a module are disposed at ends of the wires opposite from the ends of the wires at which the same components of the next adjacent modules are disposed so that the cam followers of alternate modules react with one of the cams and the remaining cam followers of the remaining modules react with the other cam. There is also including stress limiting means in the form of coil springs associated with alternate ends of the wires for limiting the stress or strain in the wires.

Hochstein, P.A.; Milton, H.W.; Pringle, W.L.

1981-12-22

62

Calculated viscosity-distance dependence for some actively flowing lavas  

NASA Technical Reports Server (NTRS)

The importance of viscosity as a gauge of the various energy and momentum dissipation regimes of lava flows has been realized for a long time. Nevertheless, despite its central role in lava dynamics and kinematics, it remains among the most difficult of flow physical properties to measure in situ during an eruption. Attempts at reconstructing the actual emplacement viscosities of lava flows from their solidified topographic form are difficult. Where data are available on the position of an advancing flow front as a function of time, it is possible to calculate the effective viscosity of the front as a function of distance from the vent, under the assumptions of a steady state regime. As an application and test of an equation given, relevant parameters from five recent flows on Mauna Loa and Kilauea were utilized to infer the dynamic structure of their aggregate flow front viscosity as they advanced, up to cessation. The observed form of the viscosity-distance relation for the five active Hawaiian flows examined appears to be exponential, with a rapid increase just before the flows stopped as one would expect.

Pieri, David

1987-01-01

63

Dissipation flow-frames: particle, energy, thermometer  

E-print Network

We associate the following physical co-mover conditions of to different frame choices: i) Eckart: particle flow, ii) Landau-Lifshitz: energy flow, iii) J\\"uttner: moving thermometer frame. The role of fixing a flow-frame is analysed with respect to local equilibrium concentrating on dissipative currents and forces in single component relativistic fluids. The special role of a "J\\"uttner frame" is explored and contrasted to the more common Eckart and Landau-Lifshitz choices.

P. Ván; T. S. Biró

2013-05-14

64

Dissipation flow-frames: particle, energy, thermometer  

E-print Network

We associate the following physical co-mover conditions of to different frame choices: i) Eckart: particle flow, ii) Landau-Lifshitz: energy flow, iii) J\\"uttner: moving thermometer frame. The role of fixing a flow-frame is analysed with respect to local equilibrium concentrating on dissipative currents and forces in single component relativistic fluids. The special role of a "J\\"uttner frame" is explored and contrasted to the more common Eckart and Landau-Lifshitz choices.

Ván, P

2013-01-01

65

Managing talent flow. 2006 Energy and Resources  

E-print Network

of the hardest hit will be the energy and resources industry. Over the past 15 years, career opportunitiesManaging talent flow. 2006 Energy and Resources Talent Pulse Survey Report Consulting #12;Executive The Energy Council of Canada ................................................. 12 Contact information

66

Doping dependence of the upper critical field, superconducting current density and thermally activated flux flow activation energy in polycrystalline CeFeAsO1-xFx superconductors  

NASA Astrophysics Data System (ADS)

We report the results from resistivity and magnetic measurements on polycrystalline Ce oxypnictide (CeFeAsO1-xFx) samples where x spans from 0.13 to 0.25. We find that the orbital limiting field is as high as 150 T and it systematically decreases with increasing doping. The Maki parameter is greater than one across the phase diagram and the large Maki parameter suggests that orbital and Pauli limiting effects contribute to the upper critical field. The broadening of the superconducting transition in the resistivity data was interpreted using the thermally activated flux flow (TAFF) model where we find that the TAFF activation energy, U0(B), is proportional to B-? from 1 T to high fields, and ? does not significantly change with doping. However, U0 and the superconducting critical current, Jc, are peaked in the mid-doping region (x = 0.15-0.20), and not in the low (x < 0.15) or high doping (x > 0.20) regions. Furthermore, U0 is correlated with Jc and follows the two fluid model for granular samples.

Chong, S. V.; Williams, G. V. M.; Sambale, S.; Kadowaki, K.

2014-12-01

67

Temperature-gated thermal rectifier for active heat flow control.  

PubMed

Active heat flow control is essential for broad applications of heating, cooling, and energy conversion. Like electronic devices developed for the control of electric power, it is very desirable to develop advanced all-thermal solid-state devices that actively control heat flow without consuming other forms of energy. Here we demonstrate temperature-gated thermal rectification using vanadium dioxide beams in which the environmental temperature actively modulates asymmetric heat flow. In this three terminal device, there are two switchable states, which can be regulated by global heating. In the "Rectifier" state, we observe up to 28% thermal rectification. In the "Resistor" state, the thermal rectification is significantly suppressed (<1%). To the best of our knowledge, this is the first demonstration of solid-state active-thermal devices with a large rectification in the Rectifier state. This temperature-gated rectifier can have substantial implications ranging from autonomous thermal management of heating and cooling systems to efficient thermal energy conversion and storage. PMID:25010206

Zhu, Jia; Hippalgaonkar, Kedar; Shen, Sheng; Wang, Kevin; Abate, Yohannes; Lee, Sangwook; Wu, Junqiao; Yin, Xiaobo; Majumdar, Arun; Zhang, Xiang

2014-08-13

68

Instantaneous energy separation in a jet flow  

NASA Astrophysics Data System (ADS)

"Energy separation" is the re-distribution of the total energy in a fluid flow without external work or heat, so that some portion of the fluid has higher and other portion has lower total energy (temperature) than the surrounding fluid. The mechanism of energy separation in a free jet is investigated numerically and experimentally by obtaining predictions and measurements of the instantaneous velocity and total temperature distribution. The enhancement of energy separation by acoustic excitation is also studied. The numerical study is performed by simulating two dimensional unsteady flow and total temperature field of a plane shear layer and a circular jet with varying Reynolds number. The experimental investigation consists of the flow field measurement, flow visualization and total temperature field measurement. In the flow field measurement, the instantaneous velocity is measured to characterize the motion of the coherent structure of ring vortices and its response to acoustic excitation. The coherent structure and its response to acoustic excitation are visualized by a schlieren technique. A technique of simultaneous measurement of instantaneous velocity and total temperature is developed using two parallel constant temperature hot-wire anemometers. Comparisons of the total temperature measurement results with the flow field measurement results provide information on a link between total temperature fluctuation and the motion of the coherent structure, and the enhancement of energy separation by acoustic excitation. The results show that the frequencies of dominant total temperature fluctuation coincide with those of velocity fluctuation which represent the passing frequencies of ring vortices at given locations. These confirm that the mechanism of energy separation is induced by the motion of the coherent vortical structure which generates pressure fluctuations within the flow field. The results also indicate that the enhancement of energy separation by acoustic excitation results from vortex pairing processes which are induced by acoustic excitation. By introducing the skewness of the total temperature fluctuation, the characteristics of energy separation can be identified.

Han, Bumsoo

69

Energy Adventure Center. Activity Book.  

ERIC Educational Resources Information Center

Energy activities are provided in this student activity book. They include: (1) an energy walk; (2) forms of energy in the home; (3) energy conversion; (4) constructing a solar hot dog cooker (with instructions for drawing a parabola); (5) interviewing senior citizens to learn about energy use in the past; (6) packaging materials; (7) insulation;…

Carlton, Linda L.

70

Activities Handbook for Energy Education.  

ERIC Educational Resources Information Center

The purpose of this handbook is to present information about energy and to translate this information into learning activities for children. Chapter 1, "Energy: A Delicate Dilemma," presents activities intended to provide an introduction to energy and energy usage. Chapter 2, "What are the Sources of Energy?" provides background information and…

DeVito, Alfred; Krockover, Gerald H.

71

Energy spectrum of Buoyancy-driven Flows  

E-print Network

Using high-resolution direct numerical simulation and arguments based on the kinetic energy flux $\\Pi_u$, we demonstrate that for stably stratified flows, the kinetic energy spectrum $E_u(k) \\sim k^{-11/5}$, the entropy spectrum $E_\\theta(k) \\sim k^{-7/5}$, and $\\Pi_u(k) \\sim k^{-4/5}$ (Bolgiano-Obukhov scaling). This scaling is due to the depletion of kinetic energy because of buoyancy. For weaker buoyancy in stratified flows, $E_u(k)$ follows Kolmgorov's spectrum with a constant energy flux. We also argue that for Rayleigh B\\'{e}nard convection, the Bolgiano-Obukhov scaling will not hold for the bulk flow due to the positive energy supply by buoyancy and non-decreasing $\\Pi_u(k)$.

Kumar, Abhishek; Verma, Mahendra K

2014-01-01

72

Energy-flow diagrams: An LLNL contribution to energy analysis  

Microsoft Academic Search

Energy-flow diagrams, developed at the Laboratory, provide a quantitative picture of the supply and consumption of energy resources by various sectors. Many governmental and advisory agencies have adopted this practical device to study current energy use and to aid in understanding energy-use strategies. 7 figs.

Borg

1987-01-01

73

Supersonic flow with feeding of energy  

NASA Technical Reports Server (NTRS)

The present work discusses the results of some experimental studies on the possibility of attenuating shock waves in a supersonic flow. The shock waves were formed by an external source of electrical energy. An electromechanical method is described that permits partial recovery of the expended energy.

Zaremba, W.

1985-01-01

74

Energy Flow Models for the Steel Industry  

E-print Network

Energy patterns in the U. S. steel industry are examined using several models. First is an end-use model based on data in the 1994 Manufacturing Energy Consumption Survey (MECS). Then a seven-step process model is presented and material flow through...

Hyman, B.; Andersen, J. P.

75

Energy flow observables in hadronic collisions  

E-print Network

We present recent QCD calculations of energy flow distributions associated with the production of jets at wide rapidity separations in high-energy hadron collisions, and discuss the role of these observables to analyze contributions from parton showering and from multiple parton collisions.

F. Hautmann

2012-05-24

76

Energy flows : empowering New Orleans  

E-print Network

This thesis claims to develop alternative energy-harvesting systems by looking at their implementation at the residential scale in order to facilitate the economical autonomy of a community and thus improve its living ...

Guiraud, Florence Nathalie

2012-01-01

77

Electron-beam-controlled CO laser with supersonic flow of the active mixture  

Microsoft Academic Search

An electron-beam-controlled CO laser with supersonic flow of the active mixture was investigated. The specific output energy was up to 40 J g-1 and the efficiency was 14% under quasi-cw (pulses up to 10 ms duration) operating conditions. The main mechanisms influencing the energy deposited in a non-self-sustained discharge under supersonic flow conditions were identified.

A M Borodin; V A Gurashvili; V N Kuzmin; A K Kurnosov; A P Napartovich; N G Turkin; E Yu Shchekotov

1996-01-01

78

LASERS: Electron-beam-controlled CO laser with supersonic flow of the active mixture  

Microsoft Academic Search

An electron-beam-controlled CO laser with supersonic flow of the active mixture was investigated. The specific output energy was up to 40 J g-1 and the efficiency was 14% under quasi-cw (pulses up to 10 ms duration) operating conditions. The main mechanisms influencing the energy deposited in a non-self-sustained discharge under supersonic flow conditions were identified.

A. M. Borodin; V. A. Gurashvili; V. N. Kuz'min; A. K. Kurnosov; A. P. Napartovich; N. G. Turkin; E. Yu Shchekotov

1996-01-01

79

Particle Production and Flow at SIS Energies  

E-print Network

An overview is given over recent measurements of flow and particle production in the energy range from 0.1 to 2AGeV. Excitation functions for the directed sideward and the azimuthally symmetric transverse flow are presented and show the importance of flow phenomena in this incident energy regime. Rapidity density distributions are indicative of a system size dependence of the stopping process. The role of strange particles as a probe for the hot and dense phase of hadronic matter is discussed with respect to the production and propagation. The spectra of Kaons indicate an equilibration with the surrounding baryons during the expansion while their directed flow pattern is different from that of the nucleons.

N. Herrmann; FOPI Collaboration

1996-10-24

80

Energy flows, metabolism and translation  

PubMed Central

Thermodynamics provides an essential approach to understanding how living organisms survive in an organized state despite the second law. Exchanges with the environment constantly produce large amounts of entropy compensating for their own organized state. In addition to this constraint on self-organization, the free energy delivered to the system, in terms of potential, is essential to understand how a complex chemistry based on carbon has emerged. Accordingly, the amount of free energy brought about through discrete events must reach the strength needed to induce chemical changes in which covalent bonds are reorganized. The consequence of this constraint was scrutinized in relation to both the development of a carbon metabolism and that of translation. Amino acyl adenylates involved as aminoacylation intermediates of the latter process reach one of the higher free energy levels found in biochemistry, which may be informative on the range in which energy was exchanged in essential early biochemical processes. The consistency of this range with the amount of energy needed to weaken covalent bonds involving carbon may not be accidental but the consequence of the abovementioned thermodynamic constraints. This could be useful in building scenarios for the emergence and early development of translation. PMID:21930587

Pascal, Robert; Boiteau, Laurent

2011-01-01

81

Orographic Flow over an Active Volcano  

NASA Astrophysics Data System (ADS)

Orographic flows over and around an isolated volcano are studied through a series of numerical model experiments. The volcano top has a heated surface, so can be thought of as "active" but not erupting. A series of simulations with different atmospheric conditions and using both idealised and realistic configurations of the Weather Research and Forecast (WRF) model have been carried out. The study is based on the Soufriere Hills volcano, located on the island of Montserrat in the Caribbean. This is a dome-building volcano, leading to a sharp increase in the surface skin temperature at the top of the volcano - up to tens of degrees higher than ambient values. The majority of the simulations use an idealised topography, in order for the results to have general applicability to similar-sized volcanoes located in the tropics. The model is initialised with idealised atmospheric soundings, representative of qualitatively different atmospheric conditions from the rainy season in the tropics. The simulations reveal significant changes to the orographic flow response, depending upon the size of the temperature anomaly and the atmospheric conditions. The flow regime and characteristic features such as gravity waves, orographic clouds and orographic rainfall patterns can all be qualitatively changed by the surface heating anomaly. Orographic rainfall over the volcano can be significantly enhanced with increased temperature anomaly. The implications for the eruptive behaviour of the volcano and resulting secondary volcanic hazards will also be discussed.

Poulidis, Alexandros-Panagiotis; Renfrew, Ian; Matthews, Adrian

2014-05-01

82

Snowmass 2001 : jet energy flow project.  

SciTech Connect

Conventional cone jet algorithms arose from heuristic considerations of LO hard scattering coupled to independent showering. These algorithms implicitly assume that the final states of individual events can be mapped onto a unique set of jets that are in turn associated with a unique set of underlying hard scattering partons. Thus each final state hadron is assigned to a unique underlying parton. The Jet Energy Flow (JEF) analysis described here does not make such assumptions. The final states of individual events are instead described in terms of flow distributions of hadronic energy. Quantities of physical interest are constructed from the energy flow distribution summed over all events. The resulting analysis is less sensitive to higher order perturbative corrections and the impact of showering and hadronization than the standard cone algorithms.

Berger, C. F.; Berger. E. L.; Bhat, P. C.; Butterworth, J. M.; Ellis, S. D.; Flaugher, B.; Giele, W. T.; Kilgore, W.; Kulesza, A.; Lammers, S.; Magill, S.; Prosper, H.

2002-03-25

83

Biomass energy flows in Zimbabwe  

Microsoft Academic Search

Terrestrial above-ground biomass production and utilisation in Zimbabwe was analysed for the years 1985–1989. The total production of biomass energy was estimated at an annual average of 409 PJ (48.5% from agriculture, 29.8% from forestry and 21.7% from livestock). Of the 321 PJ produced from agricultural and forestry operations, 71 PJ of fuelwood was harvested and burnt alone (8.5 GJ

S. L. Hemstock; D. O. Hall

1995-01-01

84

California energy flow in 1993  

SciTech Connect

Energy consumption in the state of California decreased about 3% in 1993 reflecting continuation of the recession that was manifest in a moribund construction industry and a high state unemployment that ran counter to national recovery trends. Residential/commercial use decreased slightly reflecting a mild winter in the populous southern portion of the state, a decrease that was offset to some extent by an increase in the state population. Industrial consumption of purchased energy declined substantially as did production of self-generated electricity for in-house use. Consumption in the transportation sector decreased slightly. The amount of power transmitted by the utilities was at 1992 levels; however a smaller proportion was produced by the utilities themselves. Generation of electricity by nonutilities, primarily cogenerators and small power producers, was the largest of any state in the US. The growth in the number of private power producers combined with increased amounts of electricity sold to the public utilities set the stage for the sweeping proposals before the California Public Utility Commission to permit direct sales from the nonutilities to retail customers. California production of both oil and natural gas declined; however, to meet demand only the imports of natural gas increased. A break in the decade-long drought during the 1992--1993 season resulted in a substantial increase in the amount of hydroelectricity generated during the year. Geothermal energy`s contribution increased substantially because of the development of new resources by small power producers. Decline in steam production continued at The Geysers, the state`s largest field, principally owned and managed by a public utility. Increases in windpower constituted 1--1/2% of the total electric supply--up slightly from 1992. Several solar photo voltaic demonstration plants were in operation, but their contribution remained small.

Borg, I.Y.; Briggs, C.K.

1995-04-01

85

Dark energy domination in the Virgocentric flow  

NASA Astrophysics Data System (ADS)

Context. The standard ?CDM cosmological model implies that all celestial bodies are embedded in a perfectly uniform dark energy background, represented by Einstein's cosmological constant, and experience its repulsive antigravity action. Aims: Can dark energy have strong dynamical effects on small cosmic scales as well as globally? Continuing our efforts to clarify this question, we now focus on the Virgo Cluster and the flow of expansion around it. Methods: We interpret the Hubble diagram from a new database of velocities and distances of galaxies in the cluster and its environment, using a nonlinear analytical model, which incorporates the antigravity force in terms of Newtonian mechanics. The key parameter is the zero-gravity radius, the distance at which gravity and antigravity are in balance. Results: 1. The interplay between the gravity of the cluster and the antigravity of the dark energy background determines the kinematical structure of the system and controls its evolution. 2. The gravity dominates the quasi-stationary bound cluster, while the antigravity controls the Virgocentric flow, bringing order and regularity to the flow, which reaches linearity and the global Hubble rate at distances ?15 Mpc. 3. The cluster and the flow form a system similar to the Local Group and its outflow. In the velocity-distance diagram, the cluster-flow structure reproduces the group-flow structure with a scaling factor of about 10; the zero-gravity radius for the cluster system is also 10 times larger. Conclusions: The phase and dynamical similarity of the systems on the scales of 1-30 Mpc suggests that a two-component pattern may be universal for groups and clusters: a quasi-stationary bound central component and an expanding outflow around it, caused by the nonlinear gravity-antigravity interplay with the dark energy dominating in the flow component.

Chernin, A. D.; Karachentsev, I. D.; Nasonova, O. G.; Teerikorpi, P.; Valtonen, M. J.; Dolgachev, V. P.; Domozhilova, L. M.; Byrd, G. G.

2010-09-01

86

California energy flow in 1994  

SciTech Connect

California energy consumption increased in 1994 in keeping with a recovery from the previous mild recession years. Although unemployment remained above the national average, other indicators pointed to improved economic health. Increased energy use was registered principally in the residential/commercial and transportation end-use sectors. A cooler-than-usual winter and spring was reflected in increased consumption of natural gas, the principal space-heating fuel in the state. Because of low water levels behind state dams, utilities turned to natural gas for electrical generation and to increased imports from out-of- state sources to meet demand. Other factors, such as smaller output from geothermal, biomass, and cogenerators, contributed to the need for the large increase in electrical supply from these two sources. Nonetheless, petroleum dominated the supply side of the energy equation of the state in which transportation requirements comprise more than one-third of total energy demand. About half of the oil consumed derived from California production. Onshore production has been in slow decline; however, in 1994 the decrease was compensated for by increases from federal offshore fields. Until 1994 production had been limited by regulatory restrictions relating to the movement of the crude oil to onshore refineries. State natural gas production remained at 1993 levels. The increased demand was met by larger imports from Canada through the recent expansion of Pacific Transmission Company`s 804 mile pipeline. Deregulation of the state`s utilities moved ahead in 1994 when the California Public Utilities Commission issued its proposal on how to restructure the industry. Public hearings were conducted in which the chief issues were recovery of the utilities` capital investments, conflicts with the Public Utilities Policies Act, management of power transactions between new suppliers and former utility customers, and preservation of energy conservation programs currently sponsored by the utilities. The issues were not resolved at year-end, but the state`s public utilities began to take steps to improve their positions in a future competitive market by cutting costs, improving efficiencies operating plants, and enlarging their nonutility interests.

Borg, I.Y.; Mui, N.

1996-09-01

87

Baryon flow from SIS to AGS energies  

E-print Network

We analyze the baryon sideward and elliptic flow from SIS (0.25 $\\sim$ 2 A GeV) to AGS (2 $\\sim 11.0A$GeV) energies for Au + Au collisions in the relativistic transport model RBUU that includes all baryon resonances up to a mass of 2 GeV as well as string degrees of freedom for the higher mass continuum. There are two factors which dominantly determine the baryon flow at these energies: the momentum dependence of the scalar and vector potentials and the resonance-string degrees of freedom. We fix the explicit momentum dependence of the nucleon-meson couplings within the NL3 parameter set by the nucleon optical potential up to 1 GeV of kinetic energy. When assuming the optical potential to vanish identically for $E_{kin} \\geq 3.5$ GeV we simultaneously reproduce the sideward flow data of the FOPI, EOS, E895 and E877 collaborations, the elliptic flow data of the EOS, E895 and E877 collaborations, and approximately the rapidity and transverse mass distribution of protons at AGS energies. The gradual change from hadronic to string degrees of freedom with increasing bombarding energy can be viewed as a transition from {\\it hadronic} to {\\it string} matter, i.e. a dissolution of hadrons.

P. K. Sahu; W. Cassing; U. Mosel; A. Ohnishi

1999-11-24

88

California energy flow in 1993  

NASA Astrophysics Data System (ADS)

Energy consumption in the state of California decreased about 3% in 1993 reflecting continuation of the recession that was manifest in a moribund construction industry and a high state unemployment that ran counter to national recovery trends. Residential/commercial use decreased slightly reflecting a mild winter in the populous southern portion of the state, a decrease that was offset to some extent by an increase in the state population. Industrial consumption of purchased energy declined substantially as did production of self-generated electricity for in-house use. Consumption in the transportation sector decreased slightly. The amount of power transmitted by the utilities was at 1992 levels; however a smaller proportion was produced by the utilities themselves. Generation of electricity by nonutilities, primarily cogenerators and small power producers, was the largest of any state in the US. The growth in the number of private power producers combined with increased amounts of electricity sold to the public utilities set the stage for the sweeping proposals before the California Public Utility Commission to permit direct sales from the nonutilities to retail customers. California production of both oil and natural gas declined; however, to meet demand only the imports of natural gas increased. A break in the decade-long drought during the 1992-1993 season resulted in a substantial increase in the amount of hydroelectricity generated during the year. Geothermal energy's contribution increased substantially because of the development of new resources by small power producers. Decline in steam production continued at The Geysers, the state's largest field, principally owned and managed by a public utility. Increases in windpower constituted 1-1/2% of the total electric supply, up slightly from 1992. Several solar photovoltaic demonstration plants were in operation, but their contribution remained small.

Borg, I. Y.; Briggs, C. K.

1995-04-01

89

Science Activities in Energy: Solar Energy II.  

ERIC Educational Resources Information Center

Included in this science activities energy package are 14 activities related to solar energy for secondary students. Each activity is outlined on a single card and is introduced by a question such as: (1) how much solar heat comes from the sun? or (2) how many times do you have to run water through a flat-plate collector to get a 10 degree rise in…

Oak Ridge Associated Universities, TN.

90

Activities for Teaching Solar Energy.  

ERIC Educational Resources Information Center

Plans and activities are suggested for teaching elementary children about solar energy. Directions are included for constructing a flat plate collector and a solar oven. Activities for a solar field day are given. (SA)

Mason, Jack Lee; Cantrell, Joseph S.

1980-01-01

91

Energy dissipation in sheared granular flows  

SciTech Connect

Granular material flows describe flows of solid particles in which the interstitial fluid plays a negligible role in the flow mechanics. Examples include the transport of coal, food products, detergents, pharmaceutical tablets, and toner particles in high-speed printers. Using a two-dimensional discrete element computer simulation of a bounded, gravity-free Couette flow of particles, the heat dissipation rate per unit area is calculated as a function of position in the flow as well as overall solid fraction. The computation results compare favorably with the kinetic theory analysis for rough disks. The heat dissipation rate is also measured for binary mixtures of particles for different small to large solid fraction ratios, and for diameter ratios of ten, five, and two. The dissipation rates increase significantly with overall solid fraction as well as local strain rates and granular temperatures. The thermal energy equation is solved for a Couette flow with one adiabatic wall and one at constant temperature. Solutions use the simulation measurements of the heat dissipation rate, solid fraction, and granular temperature to show that the thermodynamic temperature increases with solid fraction and decreases with particle conductivity. In mixtures, both the dissipation rate and the thermodynamic temperature increase with size ratio and with decreasing ratio of small to large particles.

Karion, A.; Hunt, M.L.

1999-11-01

92

Quantum Processes and Energy-Momentum Flow  

E-print Network

In this paper we focus on energy flows in simple quantum systems. This is achieved by concentrating on the quantum Hamilton-Jacobi equation. We show how this equation appears in the standard quantum formalism in essentially three different but related ways, from the standard Schr\\"{o}dingier equation, from Lagrangian field theory and from the von Neumann-Moyal algebra. This equation allows us to track the energy flow using the energy-momentum tensor, the components of which are related to weak values of the four-momentum operator. This opens up a new way to explore these components empirically. The algebraic approach enables us to discuss the physical significance of the underlying non-commutative symplectic geometry, raising questions as to the structure of particles in quantum systems.

B. J. Hiley; D. Robson

2014-11-28

93

How does Energy Flow in Living Systems?  

NSDL National Science Digital Library

This textbook chapter describes the role photosynthesis, food webs, and fossil fuels in the movement of energy through the biosphere. The resource includes a student investigation, links to current news articles, and an essay-based unit assessment. A teacher's guide supports classroom use. This is chapter 9, the last chapter, in the unit, Energy Flow, exploring the transfer of energy between the atmosphere, oceans, land, and living things over short and long timescales. The resource is part of Global System Science (GSS), an interdisciplinary course for high school students that emphasizes how scientists from a wide variety of fields work together to understand significant problems of global impact.

94

Active Learning in Fluid Mechanics: Youtube Tube Flow and Puzzling Fluids Questions  

ERIC Educational Resources Information Center

Active-learning exercises appropriate for a course in undergraduate fluid mechanics are presented. The first exercise involves an experiment in gravity-driven tube flow, with small groups of students partaking in a contest to predict the experimental flow rates using the mechanical energy balance. The second exercise takes the form of an…

Hrenya, Christine M.

2011-01-01

95

Graphene plasmonic lens for manipulating energy flow  

PubMed Central

Manipulating the energy flow of light is at the heart of modern information and communication technologies. Because photons are uncharged, it is still difficult to effectively control them by electrical means. Here, we propose a graphene plasmonic (GP) lens to efficiently manipulate energy flow by elaborately designing the thickness of the dielectric spacer beneath the graphene sheet. Different from traditional metal-based lenses, the proposed graphene plasmonic lens possesses the advantages of tunability and excellent confinement of surface plasmons. It is found that the proposed lens can be utilized to focus and collimate the GP waves propagating along the graphene sheet. Particularly, the lens is dispersionless over a wide frequency range and the performance of lens can be flexibly tuned by adjusting the bias voltage. As an application of such a lens, the image transfer of two point sources with a separation of ?0/30 is demonstrated. PMID:24517981

Wang, Guoxi; Liu, Xueming; Lu, Hua; Zeng, Chao

2014-01-01

96

Computer Simulation of Active Control in Complex Turbulent Flows  

Microsoft Academic Search

Summary Advances in high-performance computing and Large-Eddy Simulation (LES) have made it pos- sible to obtain accurate solutions to complex, turbulent flows at moderate Reynolds numbers. With these advances, computational modeling of turbulent flows in order to develop, evaluate, and optimize active control strategies is feasible. Such control schemes can be used to improve the performance of engineering flow systems

S. Scott Collis; Yong Chang

1998-01-01

97

Sensitivity of the transverse flow towards symmetry energy  

E-print Network

We study the sensitivity of transverse flow towards symmetry energy in the Fermi energy region as well as at high energies. We find that transverse flow is sensitive to symmetry energy as well as its density dependence in the Fermi energy region. We also show that the transverse flow can address the symmetry energy at densities about twice the saturation density, however it shows the insensitivity towards the symmetry energy at densities $\\rho/\\rho_{0}$ $>$ 2. The mechanism for the sensitivity of transverse flow towards symmetry energy as well as its density dependence is also discussed.

Sakshi Gautam; Aman D Sood; Rajeev K Puri; J. Aichelin

2011-03-05

98

Optimal active power flow incorporating power flow control needs in flexible AC transmission systems  

Microsoft Academic Search

This paper presents a new method to incorporate the power flow control needs of flexible AC transmission system (FACTS) in studying the optimal active power flow problem. The linearized (DC) network model is used in this paper. Three main types of FACTS devices, namely thyristor controlled series compensators (TCSC), thyristor controlled phase shifters (TCPS) and unified power flow controllers (UPFC),

S. Y. Ge; T. S. Chung

1999-01-01

99

Energy flow and energy dissipation in a free surface.  

NASA Astrophysics Data System (ADS)

Turbulent flows on a free surface are strongly compressible [1] and do not conserve energy in the absence of viscosity as bulk fluids do. Despite violation of assumptions essential to Kolmogorov's theory of 1941 (K41) [2, 3], surface flows show strong agreement with Kolmogorov scaling, though intermittency is larger there. Steady state turbulence is generated in a tank of water, and the spatially averaged energy flux is measured from the four-fifth's law at each instant of time. Likewise, the energy dissipation rate as measured from velocity gradients is also a random variable in this experiment. The energy flux - dissipation rate cross-correlation is measured to be correlated in incompressible bulk flows, but strongly anti-correlated on the surface. We argue that the reason for this discrepancy between surface and bulk flows is due to compressible effects present on the surface. [1] J. R. Cressman, J. Davoudi, W. I. Goldburg, and J. Schumacher, New Journal of Physics, 6, 53, 2004. [2] U. Frisch. Turbulence: The legacy of A. N. Kolmogorov, Cambridge University Press, Cambridge, 1995. [3] A. N. Kolmogorov, Doklady Akad. Nauk SSSR, 32, 16, 1941.

Goldburg, Walter; Cressman, John

2005-11-01

100

Energy, entropy and the Ricci flow  

E-print Network

The Ricci flow is a heat equation for metrics, which has recently been used to study the topology of closed three manifolds. In this paper we apply Ricci flow techniques to general relativity. We view a three dimensional asymptotically flat Riemannian metric as a time symmetric initial data set for Einstein's equations. We study the evolution of the area A and Hawking mass M of a two dimensional closed surface under the Ricci flow. The physical relevance of our study derives from the fact that, in general relativity the area of apparent horizons is related to black hole entropy and the Hawking mass of an asymptotic round 2-sphere is the ADM energy.We begin by considering the special case of spherical symmetry to develop a physical feel for the geometric quantities involved. We then consider a general asymptotically flat Riemannian metric and derive an inequality which relates the evolution of the area of a closed surface S to its Hawking mass. We suggest that there may be a maximum principle which governs the long term existence of the asymptotically flat Ricci flow.

Joseph Samuel; Sutirtha Roy Chowdhury

2007-12-18

101

Energy efficient continuous flow ash lockhopper  

NASA Technical Reports Server (NTRS)

The invention relates to an energy efficient continuous flow ash lockhopper, or other lockhopper for reactor product or byproduct. The invention includes an ash hopper at the outlet of a high temperature, high pressure reactor vessel containing heated high pressure gas, a fluidics control chamber having an input port connected to the ash hopper's output port and an output port connected to the input port of a pressure letdown means, and a control fluid supply for regulating the pressure in the control chamber to be equal to or greater than the internal gas pressure of the reactor vessel, whereby the reactor gas is contained while ash is permitted to continuously flow from the ash hopper's output port, impelled by gravity. The main novelty resides in the use of a control chamber to so control pressure under the lockhopper that gases will not exit from the reactor vessel, and to also regulate the ash flow rate. There is also novelty in the design of the ash lockhopper shown in two figures. The novelty there is the use of annular passages of progressively greater diameter, and rotating the center parts on a shaft, with the center part of each slightly offset from adjacent ones to better assure ash flow through the opening.

Collins, Earl R., Jr. (inventor); Suitor, Jerry W. (inventor); Dubis, David (inventor)

1989-01-01

102

ENTRAINED-FLOW ADSORPTION OF MERCURY USING ACTIVATED CARBON  

EPA Science Inventory

Bench-scale experiments were conducted in a flow reactor to simulate entrained-flow capture of elemental mercury (Hg) by activated carbon. Adsorption of Hg by several commercial activated carbons was examined at different carbon-to-mercury (C:Hg) ratios (by weight) (600:1 - 29000...

103

Money versus Time: Evaluation of Flow Control in Terms of Energy Consumption and Convenience  

E-print Network

Flow control with the goal of reducing the skin friction drag on the fluid-solid interface is an active fundamental research area, motivated by its potential for significant energy savings and reduced emissions in the transport sector. Customarily, the performance of drag reduction techniques in internal flows is evaluated under two alternative flow conditions, i.e. at constant mass flow rate or constant pressure gradient. Successful control leads to reduction of drag and pumping power within the former approach, whereas the latter leads to an increase of the mass flow rate and pumping power. In practical applications, however, money and time define the flow control challenge: a compromise between the energy expenditure (money) and the corresponding convenience (flow rate) achieved with that amount of energy has to be reached so as to accomplish a goal which in general depends on the specific application. Based on this idea, we derive two dimensionless parameters which quantify the total energy consumption an...

Frohnapfel, Bettina; Quadrio, Maurizio

2012-01-01

104

Solar Activity and Energy  

NSDL National Science Digital Library

By performing various activities to model the magnetic fields around the sun, students will gain an understanding of how the restructuring of these magnetic fields can cause a variety of seemingly unrelated shapes and phenomena. They will discover how changes in this magnetic field cause phenomena like coronal mass ejections, filaments, sunspots, and magnetic loops. Students will also examine images of coronal mass ejections and magnetic loops to determine their speeds. They will also gain an understanding of why the surface of the sun is so active and how magnetism on the sun causes gases to move.

105

ERDA's Fossil Energy Activities  

ERIC Educational Resources Information Center

The intended coordinative role of the Council on Environmental Quality (CEQ), as defined under the National Environmental Policy Act, is compared and contrasted with its actual activities since its formation in 1969. The Council on Environmental Quality's success has been varied and is subject to dispute. (BT)

White, Philip C.

1976-01-01

106

Dark energy domination in the Virgocentric flow  

E-print Network

The standard \\LambdaCDM cosmological model implies that all celestial bodies are embedded in a perfectly uniform dark energy background, represented by Einstein's cosmological constant, and experience its repulsive antigravity action. Can dark energy have strong dynamical effects on small cosmic scales as well as globally? Continuing our efforts to clarify this question, we focus now on the Virgo Cluster and the flow of expansion around it. We interpret the Hubble diagram, from a new database of velocities and distances of galaxies in the cluster and its environment, using a nonlinear analytical model which incorporates the antigravity force in terms of Newtonian mechanics. The key parameter is the zero-gravity radius, the distance at which gravity and antigravity are in balance. Our conclusions are: 1. The interplay between the gravity of the cluster and the antigravity of the dark energy background determines the kinematical structure of the system and controls its evolution. 2. The gravity dominates the qu...

Chernin, A D; Nasonova, O G; Teerikorpi, P; Valtonen, M J; Dolgachev, V P; Domozhilova, L M; Byrd, G G

2010-01-01

107

Activation entropy, activation energy, and magnetic viscosity  

NASA Astrophysics Data System (ADS)

Starting from an exact quantum-statistical description, the influence of the shape of the energy landscape on the magnetic viscosity is investigated. Magnetic phase-space analysis based on Kramers' escape-rate theory of chemical reaction kinetics theory shows that the activation entropy associated with thermally activated hopping modifies the magnetic viscosity by reducing the attempt-frequency prefactor compared to an earlier prediction by Brown [W. F. Brown, Phys. Rev. 130, 1677 (1963)]. Energetic contributions are analyzed in terms of a model applicable to a range of coherent and noncoherent magnetization processes, and in the long-time limit deviations from the linear logarithmic magnetic-viscosity law are found.

Skomski, R.; Kirby, R. D.; Sellmyer, D. J.

1999-04-01

108

Energy Requirements of Grazing Activity  

Technology Transfer Automated Retrieval System (TEKTRAN)

Grazing dairy cows expend more energy than confined dairy cows due to grazing activity as well as walking between the pasture and the milking parlor twice a day. The amount of energy expended depends on a variety of factors, including weather, slope, and distance. This summary article was developed ...

109

High energy density Z-pinch plasmas using flow stabilization  

NASA Astrophysics Data System (ADS)

The ZaP Flow Z-Pinch research project[1] at the University of Washington investigates the effect of sheared flows on MHD instabilities. Axially flowing Z-pinch plasmas are produced that are 100 cm long with a 1 cm radius. The plasma remains quiescent for many radial Alfvén times and axial flow times. The quiescent periods are characterized by low magnetic mode activity measured at several locations along the plasma column and by stationary visible plasma emission. Plasma evolution is modeled with high-resolution simulation codes - Mach2, WARPX, NIMROD, and HiFi. Plasma flow profiles are experimentally measured with a multi-chord ion Doppler spectrometer. A sheared flow profile is observed to be coincident with the quiescent period, and is consistent with classical plasma viscosity. Equilibrium is determined by diagnostic measurements: interferometry for density; spectroscopy for ion temperature, plasma flow, and density[2]; Thomson scattering for electron temperature; Zeeman splitting for internal magnetic field measurements[3]; and fast framing photography for global structure. Wall stabilization has been investigated computationally and experimentally by removing 70% of the surrounding conducting wall to demonstrate no change in stability behavior.[4] Experimental evidence suggests that the plasma lifetime is only limited by plasma supply and current waveform. The flow Z-pinch concept provides an approach to achieve high energy density plasmas,[5] which are large, easy to diagnose, and persist for extended durations. A new experiment, ZaP-HD, has been built to investigate this approach by separating the flow Z-pinch formation from the radial compression using a triaxial-electrode configuration. This innovation allows more detailed investigations of the sheared flow stabilizing effect, and it allows compression to much higher densities than previously achieved on ZaP by reducing the linear density and increasing the pinch current. Experimental results and scaling analyses will be presented. In addition to studying fundamental plasma science and high energy density physics, the ZaP and ZaP-HD experiments can be applied to laboratory astrophysics.

Shumlak, U.; Golingo, R. P.; Nelson, B. A.; Bowers, C. A.; Doty, S. A.; Forbes, E. G.; Hughes, M. C.; Kim, B.; Knecht, S. D.; Lambert, K. K.; Lowrie, W.; Ross, M. P.; Weed, J. R.

2014-12-01

110

Numerical simulations of laser energy deposition for supersonic flow control  

Microsoft Academic Search

This thesis deals with the computational study of localized laser energy deposition in supersonic flows. This study is part of an effort to develop dynamic flow control mechanisms which can tackle critical flow conditions occurring due to shock-shock interactions in high speed flight. A model for Nd:YAG laser energy deposition in air has been developed for the purpose of this

Ramnath Kandala

2005-01-01

111

Dark Energy Domination In The Virgocentric Flow  

NASA Astrophysics Data System (ADS)

Dark energy (DE) was first observationally detected at large Gpc distances. If it is a vacuum energy formulated as Einstein's cosmological constant, ?, DE should also have dynamical effects at much smaller scales. Previously, we found its effects on much smaller Mpc scales in our Local Group (LG) as well as in other nearby groups. We used new HST observations of member 3D distances from the group centers and Doppler shifts. We find each group's gravity dominates a bound central system of galaxies but DE antigravity results in a radial recession increasing with distance from the group center of the outer members. Here we focus on the much larger (but still cosmologically local) Virgo Cluster and systems around it using new observations of velocities and distances. We propose an analytic model whose key parameter is the zero-gravity radius (ZGR) from the cluster center where gravity and DE antigravity balance. DE brings regularity to the Virgocentric flow. Beyond Virgo's 10 Mpc ZGR, the flow curves to approach a linear global Hubble law at larger distances. The Virgo cluster and its outer flow are similar to the Local Group and its local outflow with a scaling factor of about 10; the ZGR for Virgo is 10 times larger than that of the LG. The similarity of the two systems on the scales of 1 to 30 Mpc suggests that a quasi-stationary bound central component and an expanding outflow applies to a wide range of groups and clusters due to small scale action of DE as well as gravity. Chernin, et al 2009 Astronomy and Astrophysics 507, 1271 http://arxiv.org/abs/1006.0066 http://arxiv.org/abs/1006.0555

Byrd, Gene; Chernin, A. D.; Karachentsev, I. D.; Teerikorpi, P.; Valtonen, M.; Dolgachev, V. P.; Domozhilova, L. M.

2011-04-01

112

Great Lakes Ecosystems Flow of energy through ecosystems; recycling of  

E-print Network

­ Autotrophs ­ Heterotrophs ­ Saprotrophs #12;2 Energy Flow · Autotrophs ­ Self Feeders · Get their energy from · Saprotrophs ­ Decomposers · get their energy from dead organic material · Examples: bacteria, fungi

Cochran-Stafira, D. Liane

113

Assay of ?-glucosidase inhibitory activity using flow-biosensor system  

Microsoft Academic Search

A convenient and continuous method for the assay of ?-glucosidase (AGH) inhibitory activity was developed using a continuous-flow\\/stopped-flow system combined with biosensors. The amount of glucose liberated from maltose by the action of AGH was quantified by an immobilized glucose oxidase (GOD) reactor with a Clark oxygen sensor in the downstream. The immobilized AGH reactor was set in the flow-line.

Kiyoshi Matsumoto; Kiyofumi Takayama; Kanthi J. M. Abesundara; Toshiro Matsui

2003-01-01

114

Active Lava Flow near Hawai'i Volcanoes National Park  

USGS Multimedia Gallery

Areas of flowing lava show up as bright spots in this image of the active lava flow that extends south from the east rift to the ocean, near the eastern boundary of Hawai'i Volcanoes National Park. The image is a composite of a regular photo and a new ARRA-funded thermal infrared camera that will be...

115

ELEMENTAL MERCURY CAPTURE BY ACTIVATED CARBON IN A FLOW REACTOR  

EPA Science Inventory

The paper gives results of bench-scale experiments in a flow reactor to simulate the entrained-flow capture of elemental mercury (Hgo) using solid sorbents. Adsorption of Hgo by a lignite-based activated carbon (Calgon FGD) was examined at different carbon/mercury (C/Hg) rat...

116

Active Boundary Layer Trip for Supersonic Flows  

NASA Astrophysics Data System (ADS)

The last decade has been full of excitement and success for the hypersonic community thanks to various Scramjet ground tests and launches. These studies have shown promising potentials but the viability to perform commercial flights at Mach 8 is still to be demonstrated. An ideal Scramjet is one which is capable of self- starting over a wide range of angles of attack and Mach number. The Scramjet designer has to ensure that the boundary layer over the inlet ramp is fully turbulent where shocks impact, hence reducing the risks of chocked flow conditions. Most studies have issued the efficiency of roughness trip to trigger the boundary layer transition. At hypersonic speed, heat transfer and drag dramatically increase resulting in skin friction averaging at 40% of the overall drag. This study investigates the possibility of triggering transition using perpendicular air jets on a flat plate place in a hypersonic cross-flow. Experiments were conducted in the von Karman Institute hypersonic blow down wind tunnel H3. This facility is mounted with a Mach 6 contoured nozzles and provides flows with Reynolds number in the range of 10x106/m to 30x106/m. The model consist of a flat plate manufactured with a built -in settling chamber, equipped with a pressure tap and a thermocouple to monitor the jet conditions. A first flat plate was manufactured with a black-coated Plexiglas top, for surface heat transfer measurement using an infrared camera. On the second model, a Upilex sheet equipped with 32 thin film gages was glued, time dependent heat transfer measurements up to 60kHz. The jet injection conditions have been varied and a Mach number of 5.5 kept constant. The flow topology was investigated using fast schlieren techniques and oil flow, in order to gain a better understanding.

Schloegel, F.; Panigua, G.; Tirtey, S.

2009-01-01

117

Physics of active flow control around a pillar at the micro scale  

NASA Astrophysics Data System (ADS)

The use of microchannels for heat transfer enhancement has been studied for the last few decades. To take full advantage of a microchannel, various approaches such as two-phase flow, enhanced heat transfer surface, and flow boiling across pin fins entrenched inside a microchannel have been studied. Among them, micro pin fins heat exchangers, similar to their conventional counterparts have been seriously considered due to their superior heat removal performance throughout the extended surface area. In addition, an early transition to turbulent flow via micro pin fins is believed to improve heat transfer at the micro scale. Therefore, the aim of this study is to extend fundamental knowledge of flow around a micro pin fin with and without active flow. The flow field around a micro pillar was measured using micro particle image velocimetry (muPIV), and the turbulent kinetic energy (TKE ) of the flow was measured to quantify flow mixing around the micro pillar. It was found that an early transition to an unsteady flow was not achieved through the micro pillar due to the inherently small height-to-diameter ratio of the pillar, and the corresponding TKE around the micro pillar was not significant in a quasi-steady flow regime. Active flow control via a steady jet was employed through the slit on the micro pillar surface, where the circumferential location of the slit was varied. The velocity field as well as the TKE of the controlled flow was measured to determine the effect of active flow control at the micro scale. Parametric studies were performed and comparison of the various momentum coefficient, flow regime, and the azimuthal location of the control jet were conducted. Suction was introduced as alternative control scheme, and compared to a steady jet. It was found that mixing was significantly enhanced through the steady jet whereas suction was not successful with same momentum coefficients.

Jung, Junkyu

2011-12-01

118

The Electrochemical Flow Capacitor: Capacitive Energy Storage in Flowable Media  

NASA Astrophysics Data System (ADS)

Electrical energy storage (EES) has emerged as a necessary aspect of grid infrastructure to address the increasing problem of grid instability imposed by the large scale implementation of renewable energy sources (such as wind or solar) on the grid. Rapid energy recovery and storage is critically important to enable immediate and continuous utilization of these resources, and provides other benefits to grid operators and consumers as well. In past decades, there has been significant progress in the development of electrochemical EES technologies which has had an immense impact on the consumer and micro-electronics industries. However, these advances primarily address small-scale storage, and are often not practical at the grid-scale. A new energy storage concept called "the electrochemical flow capacitor (EFC)" has been developed at Drexel which has significant potential to be an attractive technology for grid-scale energy storage. This new concept exploits the characteristics of both supercapacitors and flow batteries, potentially enabling fast response rates with high power density, high efficiency, and long cycle lifetime, while decoupling energy storage from power output (i.e., scalable energy storage capacity). The unique aspect of this concept is the use of flowable carbon-electrolyte slurry ("flowable electrode") as the active material for capacitive energy storage. This dissertation work seeks to lay the scientific groundwork necessary to develop this new concept into a practical technology, and to test the overarching hypothesis that energy can be capacitively stored and recovered from a flowable media. In line with these goals, the objectives of this Ph.D. work are to: i) perform an exploratory investigation of the operating principles and demonstrate the technical viability of this new concept and ii) establish a scientific framework to assess the key linkages between slurry composition, flow cell design, operating conditions and system performance. To achieve these goals, a combined experimental and computational approach is undertaken. The technical viability of the technology is demonstrated, and in-depth studies are performed to understand the coupling between flow rate and slurry conductivity, and localized effects arising within the cell. The outlook of EFCs and other flowable electrode technologies is assessed, and opportunities for future work are discussed.

Dennison, Christopher R.

119

Energy flow in an arctic aquatic ecosystem  

SciTech Connect

This project has been using natural isotope abundances to trace major pathways of energy flow to consumers in Imnavait Creek and the tundra ecosystem of the R4D watershed with comparative work in the coastal tundra. We are processing samples collected at the R4D intensive site over the past three years and are comparing these data with similar samples collected from the coastal plain. Our approach is to determine if carbon is accumulating in upland and coastal tundra; to determine the role of eroded peat carbon in the aquatic ecosystem; and to determine the distribution of carbon and nitrogen isotopes in the tundra-pond ecosystem to establish the feasibility of using natural differences as tracers.

Schell, D.M.

1993-05-01

120

Energy flow in an arctic aquatic ecosystem  

SciTech Connect

This project has been using natural isotope abundances to trace major pathways of energy flow to consumers in Imnavait Creek and the tundra ecosystem of the R4D watershed with comparative work in the coastal tundra. We are processing samples collected at the R4D intensive site over the past three years and are comparing these data with similar samples collected from the coastal plain. Our approach is to determine if carbon is accumulating in upland and coastal tundra; to determine the role of eroded peat carbon in the aquatic ecosystem; and to determine the distribution of carbon and nitrogen isotopes in the tundra-pond ecosystem to establish the feasibility of using natural differences as tracers.

Schell, D.M.

1993-01-01

121

Deuterons and flow: At intermediate AGS energies  

SciTech Connect

A quantitative model, based on hadronic physics and Monte Carlo cascading is applied to heavy ion collisions at BNL-AGS and BEVALAC energies. The model was found to be in excellent agreement with particle spectra where data previously existed, for Si beams, and was able to successfully predict the spectra where data was initially absent, for Au beams. For Si + Au collisions baryon densities of three or four times the normal nuclear matter density ({rho}{sub 0}) are seen in the theory, while for Au + Au collisions, matter at densities up to 10 {rho}{sub 0} is anticipated. The possibility that unusual states of matter may be created in the Au beams and potential signatures for its observation, in particular deuterons and collective flow, are considered.

Kahana, D.E. [State Univ. of New York, Stony Brook, NY (United States); Pang, Y. [Brookhaven National Lab., Upton, NY (United States)]|[Columbia Univ., New York, NY (United States); Kahana, S.H. [Brookhaven National Lab., Upton, NY (United States)

1996-06-01

122

Government: Its Energy Policy and Activities.  

ERIC Educational Resources Information Center

Discusses the federal government's progress toward the formation of a national energy policy and briefly describes the energy activities of government agencies, especially the Department of Energy. (SK)

Winek, Gary J.

1980-01-01

123

U.S. energy flow, 1992  

SciTech Connect

This report discusses energy consumption in the United States which rose slightly in 1992, reflecting partial recovery from the economic recession that prevailed during the previous year. Increases were registered in all major end use sectors with the largest occurring in the industrial sector. Energy consumed for transportation, which reflects improved passenger fleet efficiencies and a growing population as well as economic activity, returned to 1989--1990 levels. The United States depended on petroleum for 41 % of its energy supply. Imports of crude oil and petroleum products increased to compensate for decline in domestic production. Imports rose to 44% of supply. Because domestic production of natural gas was close to 1991`s, increased demand was accommodated by larger (16%) imports from Canada. Coal production was virtually unchanged from 1991 and thus well below 1990 production. Nonetheless coal supplied about one quarter of US energy needs, primarily for electrical generation. For the third year electricity transmitted by utilities departed from historic growth trends; it remained at 1991 levels. The Energy Policy Act of 1992 was signed into law in October. Among its many provisions, this act encourages independent power producers to compete with the utilities in wholesale production of electricity, streamlines the licensing of nuclear power plants, promotes the development of renewable energy sources through tax incentives, imposes efficiency standards on many manufacturing items, requires federal and private fleets to buy vehicles that run on alternative fuels, and requires the Secretary of Energy to develop a plan to decrease oil consumption, increase the use of renewable energy, improve conversion efficiencies, and limit the emission of greenhouse gases.

Borg, I.Y.; Briggs, C.K.

1993-10-01

124

Energy of eigenmodes in magnetohydrodynamic flows of ideal fluids  

SciTech Connect

Energy of eigenmodes in magnetohydrodynamic (MHD) flows of ideal fluids is studied analytically. It is shown that the energy of unstable modes is zero, while the energy of stable oscillatory modes (waves) can assume both positive and negative values. Negative energy waves always correspond to eigenmodes with a finite component of the wave-vector along the flow. Coupling of negative and positive energy waves is shown to be a universal mechanism of MHD instabilities in flowing media. As an example, the energy of eigenmodes of magnetorotational instability is calculated.

Khalzov, I. V.; Smolyakov, A. I. [University of Saskatchewan, 116 Science Place, Saskatoon, Saskatchewan, S7N5E2 (Canada); Russian Research Center 'Kurchatov Institute', 1 Kurchatov Sq., Moscow, 123182 (Russian Federation); Ilgisonis, V. I. [Russian Research Center 'Kurchatov Institute', 1 Kurchatov Sq., Moscow, 123182 (Russian Federation)

2008-05-15

125

Flow speed measurement and rheometry by pulsed neutron activation  

SciTech Connect

Pulsed Neutron Activation (PNA) is a means of non-invasive flow velocity measurement based on tagging the flowing medium with a short-lived radioactivity. Previous work with salt or dye-tagging showed poor accuracy in turbulent and failed in laminar flow when conventional data processing was used. However, use of a data acquisition and processing scheme that is based on tag dispersion modelling can produce absolute values over a wide range of flow speeds and regimes with high accuracy. For non-Newtonian/laminar flow, rheological information can also be obtained. The inherently non-intrusive nature of PNA tagging makes this scheme available for slurry measurements. The performance of PNA in slurry flow at up to 60 percent solid content was compared to full-flow diversion and weighing. Errors ranged from less than 0.2% at high Reynolds' numbers to about 2% for paste flow. Rheological parameters (yield shear stress or flow behaviour index) could be determined with an accuracy that compared to that of a spindle viscometer with grab-samples. The PNA scheme thus offers a unique means of studying slurry flow in a dedicated laboratory facility, or of providing calibration for other flowmeters in an industrial plant through temporary installation by a team of expert consultants. 27 refs., 8 figs.

Porges, K.G.A.; Cox, S.A.; Herzenberg, C.; Kampschoer, C.

1988-01-01

126

Modelling flow dynamics in an active submarine channel  

NASA Astrophysics Data System (ADS)

A novel 2.5D shallow water model, incorporating vertical stratification of flow density and velocity, has been developed to investigate the hydro- and morphodynamics of submarine meandering systems. Successfully verified against rigorous analytical and numerical test cases, the model has been applied to investigate the flow dynamics within an active submarine channel, formed at the exit of the Strait of Bosphorous in the SW Black Sea. Further, the model has been verified by comparing predicted flow hydrodynamic conditions, including velocity, density and stratification, to equivalent data directly observed within the Black Sea submarine channel. Development of the model has highlighted the importance of stratification as a primary control on submarine flow hydrodynamics. Data obtained from the Black Sea submarine channel system, and the model presented herein, demonstrates that in submarine systems density stratification acts to keep the majority of the flow bounded within the channel system, with a dilute mixing layer forming above the channel boundaries. As stratification diminishes, flow overspill from the channel increases, suggesting a degree of topographic control of flow stratification not accounted for in current empirical models of submarine flow dynamics. We also highlight the fundamental differences in flow dynamics between poorly stratified saline density currents and highly stratified turbidity currents. Specifically, we suggest that flow stratification enables turbidity currents to be contained more readily within their channel systems and therefore to develop over longer distances than equivalent saline density currents.

Dorrell, Robert; Darby, Steve; Peakall, Jeff; Parsons, Dan; Sumner, Esther; Wynn, Russell

2013-04-01

127

Energy flow in an arctic aquatic ecosystem  

SciTech Connect

Natural isotope abundances to trace major pathways of energy flow to consumers in Imnavait Creek and the tundra ecosystem of the R4D watershed with comparative work in the coastal tundra. Our overall goals are to a determine if carbon is accumulating in upland and coastal tundra; determine the role of eroded peat carbon in the aquatic ecosystem; and to determine the distribution of carbon and nitrogen isotopes in the tundra-pond ecosystem to establish the feasibility of using natural differences as tracers. Past work on fishes, birds, and the prey species of insects and aquatic crustaceans has shown that peat carbon is very important in the energy supply supporting the food webs over the course of the year. Obligate freshwater fishes from the coastal lakes and Colville River have been shown to contain up to 60 percent peat carbon at the end of the winter season. In contrast, migratory shorebirds and passerines contained much smaller radiocarbon abundances in summer, indicating a major shift to recent in situ primary production in pond and stream ecosystems in summer months. For the past two years, we have narrowed our focus to the processes supplying carbon to the beaded stream system at MS-117 and have concentrated on determining the transfer and accumulation rates of carbon in the watershed.

Schell, D.M.

1988-12-31

128

Energy flow in an arctic aquatic ecosystem  

SciTech Connect

Natural isotope abundances to trace major pathways of energy flow to consumers in Imnavait Creek and the tundra ecosystem of the R4D watershed with comparative work in the coastal tundra. Our overall goals are to a determine if carbon is accumulating in upland and coastal tundra; determine the role of eroded peat carbon in the aquatic ecosystem; and to determine the distribution of carbon and nitrogen isotopes in the tundra-pond ecosystem to establish the feasibility of using natural differences as tracers. Past work on fishes, birds, and the prey species of insects and aquatic crustaceans has shown that peat carbon is very important in the energy supply supporting the food webs over the course of the year. Obligate freshwater fishes from the coastal lakes and Colville River have been shown to contain up to 60 percent peat carbon at the end of the winter season. In contrast, migratory shorebirds and passerines contained much smaller radiocarbon abundances in summer, indicating a major shift to recent in situ primary production in pond and stream ecosystems in summer months. For the past two years, we have narrowed our focus to the processes supplying carbon to the beaded stream system at MS-117 and have concentrated on determining the transfer and accumulation rates of carbon in the watershed.

Schell, D.M.

1988-01-01

129

Generalized gradient vector flow external forces for active contours1  

Microsoft Academic Search

Active contours, or snakes, are used extensively in computer vision and image processing applications, particularly to locate object boundaries. A new type of external force for active contours, called gradient vector flow (GVF) was introduced recently to address problems associated with initialization and poor convergence to boundary concavities. GVF is computed as a di?usion of the gradient vectors of a

Chenyang Xu; Jerry L. Prince

1998-01-01

130

Global flow of glasma in high energy nuclear collisions  

NASA Astrophysics Data System (ADS)

We discuss the energy flow of the classical gluon fields created in collisions of heavy nuclei at collider energies. We show how the Yang-Mills analog of Faraday's Law and Gauss' Law predicts the initial gluon flux tubes to expand or bend. The resulting transverse and longitudinal structure of the Poynting vector field has a rich phenomenology. Besides the well-known radial and elliptic flow in transverse direction, classical quantum chromodynamics predicts a rapidity-odd transverse flow that tilts the fireball for non-central collisions, and it implies a characteristic flow pattern for collisions of non-symmetric systems A+B. The rapidity-odd transverse flow translates into a directed particle flow v1 which has been observed at RHIC and LHC. The global flow fields in heavy ion collisions could be a powerful check for the validity of classical Yang-Mills dynamics in high energy collisions.

Chen, Guangyao; Fries, Rainer J.

2013-06-01

131

Control, observation and energy regulation of wake flow instabilities  

Microsoft Academic Search

A three-dimensional Galerkin model is used in feedback design to regulate the perturbation kinetic energy in the flow around a cylinder. The objective may vary from stabilization in order to reduce drag to mixing enhancement. The Landau model [H.K. Khalil, 2002] includes an oscillatory state pair and a shift mode, exchanging energy with the mean flow. Given the model's simplicity,

Gilead Tadmor; Bernd R. Noack; Andreas Dillmann; J. Gerhard; M. Pastoor; R. King; M. Morzynski

2003-01-01

132

Energy distribution and transfer in flowing hydrogen microwave plasmas  

Microsoft Academic Search

The physical and chemical properties of a hydrogen discharge in a flowing microwave plasma system were investigated. The plasma system is the mechanism utilized in an electrothermal propulsion concept to convert electromagnetic energy into the kinetic energy of flowing hydrogen gas. The physical and chemical properties were examined for absorbed powers of 20 to 100 W, pressures of 0.5 to

Randall A. Chapman

1987-01-01

133

Energy Distribution and Transfer in Flowing Hydrogen Microwave Plasmas  

Microsoft Academic Search

This thesis is an experimental investigation of the physical and chemical properties of a hydrogen discharge in a flowing microwave plasma system. The plasma system is the mechanism utilized in an electrothermal propulsion concept to convert electromagnetic energy into the kinetic energy of flowing hydrogen gas. The plasmas are generated inside a 20 cm ID resonant cavity at a driving

Randall A. Chapman

1986-01-01

134

Photospheric and sub-photospheric Flows in Active Regions  

NASA Astrophysics Data System (ADS)

The availability of continuous high-cadence and high-spatial resolution Dopplergrams allows us to study sub-surface dynamics that may be further extended to explore precursors of the solar activity. Since p-mode power is absorbed in high magnetic field regions, the helioseismic inferences in these regions are associated with large errors. In order to validate results, we use Dopplergrams from both space-borne (Helioseismic Magnetic Imager-HMI) and ground-based (Global Oscillation Network Group-GONG) observations to infer horizontal flows in photospheric and sub-photospheric layers in and around several active regions with different characteristics. The photospheric flows are calculated using local correlation tracking (LCT) method while ring-diagram analysis technique is used to infer flows in the sub-photospheric regions. A detailed comparison between flows in shear layer and photospheric layer will be made in order to study similarities and discrepancies in these results.

Jain, Kiran; Komm, Rudolf W; Tripathy, Sushanta; Ravindra, B.; Hill, Frank

2014-06-01

135

ACTIVITY BUDGETS, ENERGY EXPENDITURES, AND  

Microsoft Academic Search

Daily energT expenditures of two pairs of nesting Ferruginous Hawks were esti- mated from activity budgets, and were compared with energy intakes determined from observed prey captures. In 1974 and 1975 respectively, the adult males expended 330.9 -+ 37.8 (SD) and 374.3 ñ 18.1 kcal\\/day, whereas the adult females expended 265.3 -+ 28.3 and 294.6 ñ 34.5 kcal\\/ day. The

FERRUGINOUS HAWKS; JAMES S. WAKELEY

136

Closed-Loop Active Flow Control Systems: Actuators  

Microsoft Academic Search

Closed-loop active flow control (CLAFC), the capability to estimate, efficiently alter and maintain a flow state, relies on the control authority of available actuators as a primary enabling technology. The requirements from the actuation\\u000a systems are outlined and a critical review of available actuation technology is offered. Since the relevance of a given actuator\\u000a depends on the application, separation control

A. Seifert

137

Driving magnetic activity: differential rotation, flow structures, and surface patterns  

NASA Astrophysics Data System (ADS)

The interplay between stellar rotation and turbulent flows is a major ingredient for vertical angular momentum transport in stellar convection zone. Combined with the centrifugal force and the buoyancy force due to pole-equator temperature gradients one can expect a large-scale flow structure that is usually referred to as differential rotation and meridional flows. I review such observations for stars other than the Sun, mostly for stars significantly more active, and ask the question whether such observations can constrain the dynamo process.

Strassmeier, Klaus G.

2015-03-01

138

Chemical and biological activity in three-dimensional flows.  

PubMed

We study the dynamics of active particles advected by three-dimensional (3D) open incompressible flows, both analytically and numerically. We find that 3D reactive flows have fundamentally different dynamical features from those in 2D systems. In particular, we show that the reaction's productivity per reaction step can be enhanced, with respect to the 2D case, while the productivity per unit time in some 3D flows goes to zero in the limit of high mixing rates, in contrast to the 2D behavior, in which the productivity goes to a finite constant. These theoretical predictions are validated by numerical simulations on a generic map model. PMID:15447576

de Moura, Alessandro P S; Grebogi, Celso

2004-08-01

139

CEREBRAL ENERGY METABOLISM, GLUCOSE TRANSPORT AND BLOOD FLOW : CHANGES WITH MATURATION AND ADAPTATION TO HYPOGLYCAEMIA  

Microsoft Academic Search

SUMMARY - Brain maturation is characterized by a peak of cerebral energy metabolism and blood flow occurring between 3 and 8 years of age in humans and around 14-17 days of postnatal life in rats. This high activity coincides with the period of active brain growth. The human brain is dependent on glucose alone during that period, whereas rat brain

A. NEHLIG

140

Flow of cortical activity underlying a tactile decision in mice  

PubMed Central

Summary Perceptual decisions involve distributed cortical activity. Does information flow sequentially from one cortical area to another, or do networks of interconnected areas contribute at the same time? Here we delineate when and how activity in specific areas drives a whisker-based decision in mice. A short-term memory component temporally separated tactile “sensation” and “action” (licking). Using optogenetic inhibition (spatial resolution, 2 mm; temporal resolution, 100 ms) we surveyed the neocortex for regions driving behavior during specific behavioral epochs. Barrel cortex was critical for sensation. During the short-term memory, unilateral inhibition of anterior lateral motor cortex biased responses to the ipsilateral side. Consistently, barrel cortex showed stimulus-specific activity during sensation, whereas motor cortex showed choice-specific preparatory activity and movement-related activity, consistent with roles in motor planning and movement. These results suggest serial information flow from sensory to motor areas during perceptual decision making. PMID:24361077

Guo, Zengcai V.; Li, Nuo; Huber, Daniel; Ophir, Eran; Gutnisky, Diego; Ting, Jonathan T.; Feng, Guoping; Svoboda, Karel

2014-01-01

141

Estimated State-Level Energy Flows in 2008  

NSDL National Science Digital Library

Sankey (or Spaghetti) diagrams parse out the energy flow by state, based on 2008 data from the Dept. of Energy. These diagrams can help bring a local perspective to energy consumption. The estimates include rejected or lost energy but don't necessarily include losses at the ultimate user end that are due to lack of insulation.

A.J. Simon

142

How Large Scales Flows May Influence Solar Activity  

NASA Technical Reports Server (NTRS)

Large scale flows within the solar convection zone are the primary drivers of the Sun's magnetic activity cycle and play important roles in shaping the Sun's magnetic field. Differential rotation amplifies the magnetic field through its shearing action and converts poloidal field into toroidal field. Poleward meridional flow near the surface carries magnetic flux that reverses the magnetic poles at about the time of solar maximum. The deeper, equatorward meridional flow can carry magnetic flux back toward the lower latitudes where it erupts through the surface to form tilted active regions that convert toroidal fields into oppositely directed poloidal fields. These axisymmetric flows are themselves driven by large scale convective motions. The effects of the Sun's rotation on convection produce velocity correlations that can maintain both the differential rotation and the meridional circulation. These convective motions can also influence solar activity directly by shaping the magnetic field pattern. While considerable theoretical advances have been made toward understanding these large scale flows, outstanding problems in matching theory to observations still remain.

Hathaway, D. H.

2004-01-01

143

Activation energy measurements in rheological analysis of cheese  

Technology Transfer Automated Retrieval System (TEKTRAN)

Activation energy of flow (Ea) was calculated from temperature sweeps of cheeses with contrasting characteristics to determine its usefulness in predicting rheological behavior upon heating. Cheddar, Colby, whole milk Mozzarella, low moisture part skim Mozzarella, Parmesan, soft goat, and Queso Fre...

144

Determining characteristics of melting cheese by activation energy  

Technology Transfer Automated Retrieval System (TEKTRAN)

Activation energy of flow (Ea) between 30 and 44 deg C was measured from temperature sweeps of various cheeses to determine its usefulness in predicting rheological behavior upon heating. Seven cheese varieties were heated in a rheometer from 22 to 70 deg C, and Ea was calculated from the resulting ...

145

Active Flow Control on an Aggressive Serpentine Duct Inlet  

NASA Astrophysics Data System (ADS)

For military applications, inlet designs are constrained by low observability requirements, which call for the use of a serpentine inlet. The inlets purpose is to limit the line-of-sight to the compressor and decelerate the incoming flow while minimizing total pressure loss, distortion, and unsteadiness. In addition, in unmanned aerial vehicles, the inlet length can determine the overall size of the aircraft. For this reason, aggressive inlets can have a large impact on overall system efficiency. Experiments utilizing active flow control to mitigate separation in a highly aggressive serpentine duct (L/D=1.5), at Mach numbers up to 0.45, were conducted. Specifically, steady and unsteady flow control techniques were compared by measuring the static pressures along the inlet walls, the pressure recovery and distortion at the AIP, and the velocity field inside the duct using Particle Image Velocimetry. Through these experiments a better understanding of the highly three dimensional flow interactions was formulated.

Vaccaro, John; Amitay, Michael

2008-11-01

146

Stable Modality-Specific Activity Flows As Reflected by the Neuroenergetic Approach to the fMRI Weighted Maps  

E-print Network

Stable Modality-Specific Activity Flows As Reflected by the Neuroenergetic Approach to the fMRI word processing. In this analysis, energy flows are thought to create the stable gradients of the fMRI Approach to the fMRI Weighted Maps. PLoS ONE 7(3): e33462. doi:10.1371/journal.pone.0033462 Editor: Tianzi

Paris-Sud XI, Université de

147

Active and passive flow control on a precessing jet  

NASA Astrophysics Data System (ADS)

A precessing jet nozzle with water as the working fluid is investigated under passive and active flow control. The actuation effectiveness of 12 microjets around the nozzle inlet for active control of the precessing jet is the focus of this work. Passive control is also applied by modifying the geometry of the precessing jet either by adding a center body near the chamber exit or varying the chamber length. The flow behavior under control is studied using pressure measurement at the chamber exit plane to monitor jet precession. The pressure data are analyzed using a phase plane representation to determine the motion of the jets high-velocity region in the chamber exit plane. The standard deviation of the phase of the triggered pressure data is used for stability analysis. This analysis results in a phase diagram in terms of Reynolds number and actuation frequency. Active control can be utilized over a range of actuation frequencies (and corresponding Strouhal numbers) to control precession direction and stability which can be further enhanced with passive control mechanisms. However, the flow follows the actuation with the lowest variation when the active actuation matches with the natural Strouhal number of the nozzle jet flow.

Babazadeh, Hamed; Nobes, David S.; Koch, Charles Robert

2015-01-01

148

Benefits of Active Flow Control for Wind Turbine Blades  

Microsoft Academic Search

In this talk, the blade element momentum model is used to design a wind turbine and examine the benefit of active flow control. The results suggest that either the overall operational range of the wind turbine could be effectively enlarged by 80% with the same rated power output or the rated output power could be increased by 20% while maintaining

Guannan Wang; Basman Elhadidi; Jakub Walczak; Mark Glauser; Hiroshi Higuchi

2010-01-01

149

Anisotropic energy flow and allosteric ligand binding in albumin  

PubMed Central

Allosteric interactions in proteins generally involve propagation of local structural changes through the protein to a remote site. Anisotropic energy transport is thought to couple the remote sites, but the nature of this process is poorly understood. Here, we report the relationship between energy flow through the structure of bovine serum albumin and allosteric interactions between remote ligand binding sites of the protein. Ultrafast infrared spectroscopy is used to probe the flow of energy through the protein backbone following excitation of a heater dye, a metalloporphyrin or malachite green, bound to different binding sites in the protein. We observe ballistic and anisotropic energy flow through the protein structure following input of thermal energy into the flexible ligand binding sites, without local heating of the rigid helix bundles that connect these sites. This efficient energy transport mechanism enables the allosteric propagation of binding energy through the connecting helix structures. PMID:24445265

Li, Guifeng; Magana, Donny; Dyer, R. Brian

2014-01-01

150

Anisotropic energy flow and allosteric ligand binding in albumin  

NASA Astrophysics Data System (ADS)

Allosteric interactions in proteins generally involve propagation of local structural changes through the protein to a remote site. Anisotropic energy transport is thought to couple the remote sites, but the nature of this process is poorly understood. Here, we report the relationship between energy flow through the structure of bovine serum albumin and allosteric interactions between remote ligand binding sites of the protein. Ultrafast infrared spectroscopy is used to probe the flow of energy through the protein backbone following excitation of a heater dye, a metalloporphyrin or malachite green, bound to different binding sites in the protein. We observe ballistic and anisotropic energy flow through the protein structure following input of thermal energy into the flexible ligand binding sites, without local heating of the rigid helix bundles that connect these sites. This efficient energy transport mechanism enables the allosteric propagation of binding energy through the connecting helix structures.

Li, Guifeng; Magana, Donny; Dyer, R. Brian

2014-01-01

151

Entrainment of coarse particles in turbulent flows: An energy approach  

NASA Astrophysics Data System (ADS)

The entrainment of coarse sediment particles under the action of fluctuating hydrodynamic forces is investigated from an energy perspective. It is demonstrated that the entrainment of a grain resting on the channel boundary is possible when the instantaneous flow power transferred to it exceeds a critical level. Its complete removal from the bed matrix occurs only if the impinging flow events supply sufficient mechanical energy. The energy-based criterion is formulated theoretically for entrainment of individual spherical particles in both saltation and rolling modes. Out of the wide range of flow events that can perform mechanical work on a coarse grain, only those with sufficient power and duration or equivalent energy density and characteristic length scale may accomplish its complete dislodgement. The instantaneous velocity upstream of a mobile particle is synchronously recorded with its position, enabling the identification of the flow events responsible for grain entrainment by rolling at near incipient motion flow conditions. For each of the entrainment events, the energy transfer coefficient defined as the ratio of the mechanical work performed on the particle to the mean energy of the flow event responsible for its dislodgement obtains values ranging from 0.04 to 0.10. At the examined low-mobility flow conditions, the majority (about 80%) of the energetic structures leading to complete particle entrainment have a characteristic length of about two to four particle diameters.

Valyrakis, Manousos; Diplas, Panayiotis; Dancey, Clint L.

2013-03-01

152

The Redox flow system for solar photovoltaic energy storage  

NASA Technical Reports Server (NTRS)

A new method of storage was applied to a solar photovoltaic system. The storage method is a redox flow system which utilizes the oxidation-reduction capability of two soluble electrochemical redox couples for its storage capacity. The particular variant described separates the charging and discharging function of the system such that the electrochemical couples are simultaneously charged and discharged in separate parts of the system. The solar array had 12 solar cells; wired in order to give a range of voltages and currents. The system stored the solar energy so that a load could be run continually day and night. The main advantages of the redox system are that it can accept a charge in the low voltage range and produce a relatively constant output regardless of solar activity.

Odonnell, P.; Gahn, R. F.

1976-01-01

153

Energy-Efficient, Continuous-Flow Ash Lockhopper  

NASA Technical Reports Server (NTRS)

Pressure balance in control gas prevents loss of reactor gas. Energy efficiency of continuous-flow ash lockhopper increased by preventing hot gases from flowing out of reactor vessel through ash-hopper outlet and carrying away heat energy. Stopping loss of reactor gases also important for reasons other than energy efficiency; desired reaction product toxic or contained to prevent pollution. In improved continuous-flow ash lockhopper, pressure-driven loss of hot gas from reactor vessel through ash-hopper outlet prevented by using control gas in fluidic flow-control device to equalize pressure in reactor vessel. Also enables reactor to attain highest possible product yield with continuous processing while permitting controllable, continuous flow of ash.

Collins, Earl R., Jr.; Suitor, Jerry W.; Dubis, David

1989-01-01

154

Radiant energy receiver having improved coolant flow control means  

DOEpatents

An improved coolant flow control for use in radiant energy receivers of the type having parallel flow paths is disclosed. A coolant performs as a temperature dependent valve means, increasing flow in the warmer flow paths of the receiver, and impeding flow in the cooler paths of the receiver. The coolant has a negative temperature coefficient of viscosity which is high enough such that only an insignificant flow through the receiver is experienced at the minimum operating temperature of the receiver, and such that a maximum flow is experienced at the maximum operating temperature of the receiver. The valving is accomplished by changes in viscosity of the coolant in response to the coolant being heated and cooled. No remotely operated valves, comparators or the like are needed.

Hinterberger, H.

1980-10-29

155

Introduction to Acoustical Energy. Learning Activity.  

ERIC Educational Resources Information Center

This technology education activity will allow the students to observe acoustical energy and will put them in a problem-solving situation where they must use the movement of a sound-activated diaphragm to perform another activity. (Author)

Shackelford, Ray; Johnson, Steve

1998-01-01

156

Experimental Study on Active Control of FreeSurface Flow using Synthetic Jets  

Microsoft Academic Search

This paper presents an active control of free-surface flow pattern using synthetic jets. The present control system is composed of Particle Tracking Velocimetry (PTV), Neural Network computing (NN) and double synthetic jet actuators, as flow measurement method, flow estimator and flow controller, respectively. PTV is used to visualize flow pattern, then the state of captured flow pattern is estimated using

Tadao Ueda; Souichi Saeki; Nobuchika Aida; Kakuji Ogawara

2001-01-01

157

Possible use of vanadium redox-flow batteries for energy storage in small grids and stand-alone photovoltaic systems  

NASA Astrophysics Data System (ADS)

The all-vanadium redox-flow battery is a promising candidate for load leveling and seasonal energy storage in small grids and stand-alone photovoltaic systems. The reversible cell voltage of 1.3 to 1.4 V in the charged state allows the use of inexpensive active and structural materials. In this work, studies on the performance of inexpensive active materials for use in vanadium redox-flow batteries are reported. Additionally, a cost analysis for a load leveling and a seasonal energy storage system is given based on a flow battery technology well established in Zn-flow batteries.

Joerissen, Ludwig; Garche, Juergen; Fabjan, Ch.; Tomazic, G.

158

Energy Flow and Rapidity Gaps Between Jets in Photoproduction  

E-print Network

Energy Flow and Rapidity Gaps Between Jets in Photoproduction Angela Wyatt October 2001 Particle#ractive DIS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54 4.3 Rapidity Gaps Between Jets . . . . . . . . . . . . . . . . . . . . 65 4.3.4 Definition of Rapidity Gap Events . . . . . . . . . . . . . . . . 67 5 Data Selection

159

Flow Effects on Jet Energy Loss with Detailed Balance  

E-print Network

In the presence of collective flow a new model potential describing the interaction of the hard jet with scattering centers is derived based on the static color-screened Yukawa potential. The flow effect on jet quenching with detailed balance is investigated in pQCD. It turns out, considering the collective flow with velocity $v_z$ along the jet direction, the collective flow decreases the LPM destructive interference comparing to that in the static medium. The gluon absorption plays a more important role in the moving medium. The collective flow increases the energy gain from gluon absorption, however, decreases the energy loss from gluon radiation, which is $(1 - v_z )$ times as that in the static medium to the first order of opacity. In the presence of collective flow, the second order in opacity correction is relatively small compared to the first order. So that the total effective energy loss is decreased. The flow dependence of the energy loss will affect the suppression of high $p_T$ hadron spectrum and anisotropy parameter $v_2$ in high-energy heavy-ion collisions.

Luan Cheng; Jia Liu; Enke Wang

2014-06-03

160

Flow effects on jet energy loss with detailed balance  

NASA Astrophysics Data System (ADS)

In the presence of collective flow a new model potential describing the interaction of the hard jet with scattering centers is derived based on the static color-screened Yukawa potential. The flow effect on jet quenching with detailed balance is investigated in pQCD. It turns out, considering the collective flow with velocity v z along the jet direction, the collective flow decreases the LPM destructive interference comparing to that in the static medium. The gluon absorption plays a more important role in the moving medium. The collective flow increases the energy gain from gluon absorption, however, decreases the energy loss from gluon radiation, which is (1 - v z ) times as that in the static medium to the first order of opacity. In the presence of collective flow, the second order in opacity correction is relatively small compared to the first order. So that the total effective energy loss is decreased. The flow dependence of the energy loss will affect the suppression of high p T hadron spectrum and anisotropy parameter v 2 in high-energy heavy-ion collisions.

Cheng, Luan; Liu, Jia; Wang, EnKe

2014-11-01

161

Dynamics of a deformable active particle under shear flow.  

PubMed

The motion of a deformable active particle in linear shear flow is explored theoretically. Based on symmetry considerations, we propose coupled nonlinear dynamical equations for the particle position, velocity, deformation, and rotation. In our model, both, passive rotations induced by the shear flow as well as active spinning motions, are taken into account. Our equations reduce to known models in the two limits of vanishing shear flow and vanishing particle deformability. For varied shear rate and particle propulsion speed, we solve the equations numerically in two spatial dimensions and obtain a manifold of different dynamical modes including active straight motion, periodic motions, motions on undulated cycloids, winding motions, as well as quasi-periodic and chaotic motions induced at high shear rates. The types of motion are distinguished by different characteristics in the real-space trajectories and in the dynamical behavior of the particle orientation and its deformation. Our predictions can be verified in experiments on self-propelled droplets exposed to a linear shear flow. PMID:24050364

Tarama, Mitsusuke; Menzel, Andreas M; ten Hagen, Borge; Wittkowski, Raphael; Ohta, Takao; Löwen, Hartmut

2013-09-14

162

Self-powered water splitting using flowing kinetic energy.  

PubMed

By utilizing a water-flow-driven triboelectric nanogenerator, a fully self-powered water-splitting process is demonstrated using the electricity converted from a water flow without additional energy costs. Considering the extremely low costs, the demonstrated approach is universally applicable and practically usable for future water electrolysis, which may initiate a research direction in the field of triboelectrolysis and possibly impacts energy science in general. PMID:25413298

Tang, Wei; Han, Yu; Han, Chang Bao; Gao, Cai Zhen; Cao, Xia; Wang, Zhong Lin

2015-01-14

163

Pulsed-flow air classification for waste-to-energy  

Microsoft Academic Search

The development and testing of the concept of pulsed-flow air classification for waste-to-energy production are discussed. Air classifiers, a potentially valuable unit operation in waste-to-energy production facilities, currently do not meet expectations. Standard designs generally lose large amounts of combustible material as well as produce a fuel that is high in metal and glass contaminants. Pulsed-flow classification is presented as

Richard Ian Stessel; J. Jeffrey Peirce

1983-01-01

164

Energy Storage. Teachers Guide. Science Activities in Energy.  

ERIC Educational Resources Information Center

Included in this science activities energy package for students in grades 4-10 are 12 activities related to energy storage. Each activity is outlined on the front and back of a single sheet and is introduced by a key question. Most of the activities can be completed in the classroom with materials readily available in any community. Among the…

Jacobs, Mary Lynn, Ed.

165

Measurement of energy distribution in flowing hydrogen microwave plasmas  

NASA Technical Reports Server (NTRS)

An electrothermal propulsion concept utilizing a microwave plasma system as the mechanism to convert electromagnetic energy into kinetic energy of a flowing gas is investigated. A calorimetry system enclosing a microwave plasma system has been developed to accurately measure the energy inputs and outputs of the microwave plasma system. The rate of energy transferred to the gas can be determined to within + or - 1.8 W from an energy balance around the microwave plasma system. The percentage of the power absorbed by the microwave plasma system transferred to the hydrogen gas as it flows through the system is found to increase with the increasing flow rate, to decrease with the increasing pressure, and to be independent of the absorbed power. An upper bound for the hydrogen gas temperature is estimated from the energy content, heat capacity, and flow rate of the gas stream. A lower bound for an overall heat-transfer coefficient is then calculated, characterizing the energy loss from the hydrogen gas stream to the air cooling of the plasma discharge tube wall. The heat-transfer coefficient is found to increase with the increasing flow rate and pressure and to be independent of the absorbed power. This result indicates that a convective-type mechanism is responsible for the energy transfer.

Chapman, R.; Morin, T.; Finzel, M.; Hawley, M. C.

1985-01-01

166

Finite Elemente Large Eddy Simulation of Flows Past Bluff Bodies with Active Flow Control  

NASA Astrophysics Data System (ADS)

A semi-implicit fractional step finite element large eddy simulation (LES) method for unstructured grids has been developed. The turbulence models implemented into the code are the constant and dynamic coefficient Smagorinsky models as well as the stress similarity model of Liu et al. The technique was applied to analyzing the effects of active flow control by massless oscillatory blowing from a slot. Especially flows past bluff bodies (e.g. circular cylinder; download on a tiltrotor wing) were investigated. Numerical optimization was used to find optimum parameters such as slot location, slot angle, frequency, etc. The numerical results are compared with experimental PIV (Particle Image Velocimetry) and pressure measurements.

Kjellgren, Per; Taubert, Lutz; Wygnanski, I. J.

2001-11-01

167

Vortical ciliary flows actively enhance mass transport in reef corals  

PubMed Central

The exchange of nutrients and dissolved gasses between corals and their environment is a critical determinant of the growth of coral colonies and the productivity of coral reefs. To date, this exchange has been assumed to be limited by molecular diffusion through an unstirred boundary layer extending 1–2 mm from the coral surface, with corals relying solely on external flow to overcome this limitation. Here, we present direct microscopic evidence that, instead, corals can actively enhance mass transport through strong vortical flows driven by motile epidermal cilia covering their entire surface. Ciliary beating produces quasi-steady arrays of counterrotating vortices that vigorously stir a layer of water extending up to 2 mm from the coral surface. We show that, under low ambient flow velocities, these vortices, rather than molecular diffusion, control the exchange of nutrients and oxygen between the coral and its environment, enhancing mass transfer rates by up to 400%. This ability of corals to stir their boundary layer changes the way that we perceive the microenvironment of coral surfaces, revealing an active mechanism complementing the passive enhancement of transport by ambient flow. These findings extend our understanding of mass transport processes in reef corals and may shed new light on the evolutionary success of corals and coral reefs. PMID:25192936

Shapiro, Orr H.; Fernandez, Vicente I.; Garren, Melissa; Guasto, Jeffrey S.; Debaillon-Vesque, François P.; Kramarsky-Winter, Esti; Vardi, Assaf; Stocker, Roman

2014-01-01

168

Vortical ciliary flows actively enhance mass transport in reef corals.  

PubMed

The exchange of nutrients and dissolved gasses between corals and their environment is a critical determinant of the growth of coral colonies and the productivity of coral reefs. To date, this exchange has been assumed to be limited by molecular diffusion through an unstirred boundary layer extending 1-2 mm from the coral surface, with corals relying solely on external flow to overcome this limitation. Here, we present direct microscopic evidence that, instead, corals can actively enhance mass transport through strong vortical flows driven by motile epidermal cilia covering their entire surface. Ciliary beating produces quasi-steady arrays of counterrotating vortices that vigorously stir a layer of water extending up to 2 mm from the coral surface. We show that, under low ambient flow velocities, these vortices, rather than molecular diffusion, control the exchange of nutrients and oxygen between the coral and its environment, enhancing mass transfer rates by up to 400%. This ability of corals to stir their boundary layer changes the way that we perceive the microenvironment of coral surfaces, revealing an active mechanism complementing the passive enhancement of transport by ambient flow. These findings extend our understanding of mass transport processes in reef corals and may shed new light on the evolutionary success of corals and coral reefs. PMID:25192936

Shapiro, Orr H; Fernandez, Vicente I; Garren, Melissa; Guasto, Jeffrey S; Debaillon-Vesque, François P; Kramarsky-Winter, Esti; Vardi, Assaf; Stocker, Roman

2014-09-16

169

Benefits of Active Flow Control for Wind Turbine Blades  

NASA Astrophysics Data System (ADS)

In this talk, the blade element momentum model is used to design a wind turbine and examine the benefit of active flow control. The results suggest that either the overall operational range of the wind turbine could be effectively enlarged by 80% with the same rated power output or the rated output power could be increased by 20% while maintaining the same level of operational range when the control is on. The optimal location for the actuator is found to be on the outboard of the blade beyond half of the radius. In light of these encouraging results and based on our earlier NACA 4412 flow control studies, a characteristic airfoil (e.g. DU-96-W-180) is being tested in a new anechoic wind tunnel facility at Syracuse University to determine the airfoil lift and drag characteristics with appropriate flow control while exposed to large scale flow unsteadiness. In addition, the effects of flow controllers on the noise spectrum of the wind turbine will be also assessed and measured in the anechoic chamber.

Wang, Guannan; Elhadidi, Basman; Walczak, Jakub; Glauser, Mark; Higuchi, Hiroshi

2010-11-01

170

Slow Magnetosonic Waves and Fast Flows in Active Region Loops  

NASA Technical Reports Server (NTRS)

Recent extreme ultraviolet spectroscopic observations indicate that slow magnetosonic waves are present in active region (AR) loops. Some of the spectral data were also interpreted as evidence of fast (approx 100-300 km/s) quasiperiodic flows. We have performed three-dimensional magnetohydrodynamic (3D MHD) modeling of a bipolar AR that contains impulsively generated waves and flows in coronal loops. The model AR is initiated with a dipole magnetic field and gravitationally stratified density, with an upflow-driven steadily or periodically in localized regions at the footpoints of magnetic loops. The resulting flows along the magnetic field lines of the AR produce higher density loops compared to the surrounding plasma by injection of material into the flux tubes and the establishment of siphon flow.We find that the impulsive onset of flows with subsonic speeds result in the excitation of damped slow magnetosonic waves that propagate along the loops and coupled nonlinearly driven fast-mode waves. The phase speed of the slow magnetosonic waves is close to the coronal sound speed. When the amplitude of the driving pulses is increased we find that slow shock-like wave trains are produced. When the upflows are driven periodically, undamped oscillations are produced with periods determined by the periodicity of the upflows. Based on the results of the 3D MHD model we suggest that the observed slow magnetosonic waves and persistent upflows may be produced by the same impulsive events at the bases of ARs.

Ofman, L.; Wang, T. J.; Davila, J. M.

2012-01-01

171

Active Flow Control on Bidirectional Rotors for Tidal MHK Applications  

SciTech Connect

A marine and hydrokinetic (MHK) tidal turbine extracts energy from tidal currents, providing clean, sustainable electricity generation. In general, all MHK conversion technologies are confronted with significant operational hurdles, resulting in both increased capital and operations and maintenance (O&M) costs. To counter these high costs while maintaining reliability, MHK turbine designs can be simplified. Prior study found that a tidal turbine could be cost-effectively simplified by removing blade pitch and rotor/nacelle yaw. Its rotor would run in one direction during ebb and then reverse direction when the current switched to flood. We dubbed such a turbine a bidirectional rotor tidal turbine (BRTT). The bidirectional hydrofoils of a BRTT are less efficient than conventional hydrofoils and capture less energy, but the elimination of the pitch and yaw systems were estimated to reduce levelized cost of energy by 7.8%-9.6%. In this study, we investigated two mechanisms for recapturing some of the performance shortfall of the BRTT. First, we developed a novel set of hydrofoils, designated the yy series, for BRTT application. Second, we investigated the use of active flow control via microtabs. Microtabs are small deployable/retractable tabs, typically located near the leading or trailing edge of an air/hydrofoil with height on the order of the boundary layer thickness (1% - 2% of chord). They deploy approximately perpendicularly to the foil surface and, like gurney flaps and plain flaps, globally affect the aerodynamics of the airfoil. By strategically placing microtabs and selectively deploying them based on the direction of the inflow, performance of a BRTT rotor can be improved while retaining bidirectional operation. The yy foils were computationally designed and analyzed. They exhibited better performance than the baseline bidirectional foil, the ellipse. For example, the yyb07cn-180 had 14.7% higher (l/d)max than an ellipse of equal thickness. The yyb07cn family also had higher c{sub p,min} than equivalently thick ellipses, indicating less susceptibility to cavitation. Microtabs applied on yy foils demonstrated improved energy capture. A series of variable speed and constant speed rotors were developed with the yyb07cn family of hydrofoils. The constant speed yyb07cn rotor (yy-B02-Rcs,opt) captured 0.45% more energy than the equivalent rotor with ellipses (e-B02-Rcs,opt). With microtabs deployed (yy?t-B02-Rcs,opt), the energy capture increase over the rotor with ellipses was 1.05%. Note, however, that microtabs must be applied judiciously to bidirectional foils. On the 18% thick ellipse, performance decreased with the addition of microtabs. Details of hydrofoil performance, microtab sizing and positioning, rotor configurations, and revenue impacts are presented herein.

Shiu, Henry [Research Engineer; van Dam, Cornelis P. [Professor

2013-08-22

172

Coupling Bacterial Activity Measurements with Cell Sorting by Flow Cytometry  

Microsoft Academic Search

A new procedure to investigate the relationship between bacterial cell size and activity at the cellular level has been developed;\\u000a it is based on the coupling of radioactive labeling of bacterial cells and cell sorting by flow cytometry after SYTO 13 staining.\\u000a Before sorting, bacterial cells were incubated in the presence of tritiated leucine using a procedure similar to that

P. Servais; C. Courties; P. Lebaron; M. Troussellier

1999-01-01

173

Boeing active flow control system (BAFCS)-II  

NASA Astrophysics Data System (ADS)

The Boeing Active Flow Control (AFC) System (BAFCS) is a DARPA sponsored program to develop AFC technology to achieve a significant increase in payload for rotorcraft applications such as the V-22 tiltrotor vehicle. The program includes Computational Fluid Dynamics (CFD) analysis, wind tunnel testing and development of smart material based AFC actuators. This paper will provide an overview of the program, concentrating on the development of the AFC actuators, and is an update of reference 1,2.

Jacot, A. Dean; Calkins, Frederick T.; Mabe, Jim H.

2001-06-01

174

Energy Activities for Junior High Science.  

ERIC Educational Resources Information Center

This document is a collection of six energy education activities for junior high school science. Its purpose is to help promote knowledge about energy, provide laboratory experiences, provoke inquiry, and relate energy to society through the science curriculum. The six activities are designed to take one to three class periods. Two of the…

Beaver, David; And Others

175

Non-invasive energy meter for fixed and variable flow systems  

DOEpatents

An energy metering method and apparatus for liquid flow systems comprising first and second segments of one or more conduits through which a liquid flows, comprising: attaching a first temperature sensor for connection to an outside of the first conduit segment; attaching a second temperature sensor for connection to an outside of the second conduit segment; via a programmable control unit, receiving data from the sensors and calculating energy data therefrom; and communicating energy data from the meter; whereby the method and apparatus operate without need to temporarily disconnect or alter the first or second conduit segments. The invention operates with both variable and fixed flow systems, and is especially useful for both active and passive solar energy systems.

Menicucci, David F.; Black, Billy D.

2005-11-01

176

Cellular Links between Neuronal Activity and Energy Homeostasis  

PubMed Central

Neuronal activity, astrocytic responses to this activity, and energy homeostasis are linked together during baseline, conscious conditions, and short-term rapid activation (as occurs with sensory or motor function). Nervous system energy homeostasis also varies during long-term physiological conditions (i.e., development and aging) and with adaptation to pathological conditions, such as ischemia or low glucose. Neuronal activation requires increased metabolism (i.e., ATP generation) which leads initially to substrate depletion, induction of a variety of signals for enhanced astrocytic function, and increased local blood flow and substrate delivery. Energy generation (particularly in mitochondria) and use during ATP hydrolysis also lead to considerable heat generation. The local increases in blood flow noted following neuronal activation can both enhance local substrate delivery but also provides a heat sink to help cool the brain and removal of waste by-products. In this review we highlight the interactions between short-term neuronal activity and energy metabolism with an emphasis on signals and factors regulating astrocyte function and substrate supply. PMID:22470340

Shetty, Pavan K.; Galeffi, Francesca; Turner, Dennis A.

2012-01-01

177

Security Constrained Optimal Power Flow for an Economical Operation of FACTS Devices in Liberalized Energy Markets  

Microsoft Academic Search

Among the ongoing liberalization of the global energy markets, several technical developments in the field of power electronic-based transmission devices lead to a significant restructuring of the electric power supply. These flexible ac transmission systems (FACTS) devices enable a continuous and wear-resistant control of active and reactive power flows as well as voltage control. The incorporation of the control capabilities

C. Lehmkoster

2002-01-01

178

Active Control of Flow over a Sphere for Drag Reduction  

NASA Astrophysics Data System (ADS)

In the last APS (Vol. 44, No. 8, p. 158 (1999)), we showed that the drag on the sphere at Re =10^5 is reduced by a periodic blowing and suction from the slots on the sphere surface. The amount of drag reduction depended on the forcing frequency ff (forcing amplitude was kept the same as 0.1 u_?). At ff ~= f_ns (natural shedding frequency), the drag was slightly increased, whereas, with increasing f_f, the drag first decreased and then increased, showing a minimum drag at ff ~= 8 f_ns. The amount of maximum drag reduction was about 25%. In the present study, we present flow modifications due to the high-frequency forcing (ff ~= 8 f_ns), using the hot-wire measurement and flow visualization. The streamwise and transverse velocity fluctuations and Reynolds shear stress are significantly reduced and the locations of those peaks move toward the center of the sphere. The energy peak at the natural shedding frequency nearly disappears and the energies at large frequencies are decreased due to control. The energy peak at the forcing frequency is found just behind the sphere but disappears at further downstream locations, indicating that the forcing affects near-wake dynamics. The flow visualization clearly shows that the detaching shear layer is more attracted to the sphere centerline, the bubble size is significantly reduced, and the motion inside the bubble is very weak, confirming the drag reduction by the high-frequency forcing.

Park, Jinil; Jeon, Woo-Pyung; Choi, Haecheon

2000-11-01

179

Energy Flows in the Developing World  

Microsoft Academic Search

Out of sheer necessity, the developing countries rely almost entirely on renewable energy forms such as wood and biogas; unfortunately, many of the same countries may be pursuing developmental strategies that increase their dependence on natural gas and other scarce fossil fuels, according to Canada's University of Manitoba. Detailed studies of energy use in developing countries are becoming more frequent,

Vaclav Smil

1979-01-01

180

Energy Flow Diagrams for Teaching Physics Concepts  

Microsoft Academic Search

Energy is arguably the central unifying concept in physics. The validity of the principles of energy extends almost without change from ``classical'' physics through all of modern physics. Even processes that are too complex or too far outside the Newtonian regime to be easily described in terms of forces can be described in an accurate and conceptually transparent manner in

Art Hobson

2004-01-01

181

Variable flow -- the quest for system energy efficiency  

SciTech Connect

Varying condenser water flow has long been used as a method of controlling head pressure in water-cooled refrigeration systems. This method of head pressure control has been applied successfully on systems with scroll, reciprocating, heli-rotor, and centrifugal compressors. Condenser water flow is altered either by bypassing the condenser via a three-way valve or by throttling flow with a two-way valve. Today, the affordability and potential energy savings of adjustable speed drives makes this the preferred method of varying flow. In the quest for greater energy savings, many designers propose to vary the flow of water through the evaporators of chillers also. This feat is not as easily accomplished as the first. There are system designs that allow variable flow of chilled water at the system level while maintaining constant flow through the chiller evaporator. Yet in spite of the risk and the presence of other variable options, some still wish to vary the flow of chilled water through the evaporator by large proportions. Can it be done? Of course! However, there are a few engineering problems that must be tackled to accomplish this feat. This paper delineates those problems.

Eppelheimer, D.M. [Trane Co., LaCrosse, WI (United States)

1996-12-31

182

The structure of electromagnetic energy flows in continuous media  

Microsoft Academic Search

A formulation of electromagnetism in continuous media is proposed that relies on the identification of the different existing electromagnetic energy reservoirs and of the flows between them. A structure is so revealed, which constitutes a natural framework to establish the partial differential equations ruling electromagnetic systems. This energy-based formulation, which unlike Maxwell's equations also integrates the material aspects, clarifies several

François Henrotte; Kay Hameyer

2006-01-01

183

Energy and Color Flow in Dijet Rapidity Gaps  

Microsoft Academic Search

When rapidity gaps in high- pT dijet events are identified by energy flow in the central region, they may be calculated from factorized cross sections in perturbative QCD, up to corrections that behave as inverse powers of the central region energy. Although power-suppressed corrections may be important, a perturbative calculation of dijet rapidity gaps in pp¯ scattering, using a valence

Gianluca Oderda; George Sterman

1998-01-01

184

Active attenuation of acoustic disturbances in pulsed, flowing gas lasers  

SciTech Connect

Application of active attenuation to the control of sound in pulsed lasers is discussed. In order to quantify the potential benefits of active attenuation, the muffler volumes required for a 40 dB reduction in laser sound power were calculated for systems with and without active attenuators. The laser cavity was taken to be 0.5 m in the flow direction, with a duct cross section of 0.5 x 2.0 m and a gas sound speed of 550 m/s. It is shown that an active attenuator emitting only a few hundredths of a watt would enable a reduction in the passive muffler volume of about 35%.

Lavan, M.J. (U.S. Army, Ballistics Missile Defense Advanced Technology Center, Huntsville, AL); French, F.W. (W. J. Schafer Associates, Wakefield, MA)

1982-03-01

185

Energy momentum flows for the massive vector field  

E-print Network

We present a causal trajectory interpretation for the massive vector field, based on the flows of rest energy and a conserved density defined using the time-like eigenvectors and eigenvalues of the stress-energy-momentum tensor. This work extends our previous work which used a similar procedure for the scalar field. The massive, spin-one, complex vector field is discussed in detail and solutions are classified using the Pauli-Lubanski spin vector. The flows of energy-momentum are illustrated in a simple example of standing waves in a plane.

George Horton; Chris Dewdney

2006-09-26

186

Continuous flow, evaporative-type thermal energy recovery apparatus and method for thermal energy recovery  

Microsoft Academic Search

A continuous flow, evaporative-type thermal energy recovery apparatus comprises an evaporator unit to which are supplied continuous pressurized flows of hot water and air, and in which a portion of the hot water is evaporated into the air, preferably to completely saturate the air with moisture. Connected to receive the resulting flow of pressurized, water saturated air from the evaporator

Bissell

1978-01-01

187

Hydrogen-Bromine Flow Battery: Hydrogen Bromine Flow Batteries for Grid Scale Energy Storage  

SciTech Connect

GRIDS Project: LBNL is designing a flow battery for grid storage that relies on a hydrogen-bromine chemistry which could be more efficient, last longer and cost less than today’s lead-acid batteries. Flow batteries are fundamentally different from traditional lead-acid batteries because the chemical reactants that provide their energy are stored in external tanks instead of inside the battery. A flow battery can provide more energy because all that is required to increase its storage capacity is to increase the size of the external tanks. The hydrogen-bromine reactants used by LBNL in its flow battery are inexpensive, long lasting, and provide power quickly. The cost of the design could be well below $100 per kilowatt hour, which would rival conventional grid-scale battery technologies.

None

2010-10-01

188

Mechanical energy flow models of rods and beams  

NASA Technical Reports Server (NTRS)

It has been proposed that the flow of mechanical energy through a structural/acoustic system may be modeled in a manner similar to that of flow of thermal energy/in a heat conduction problem. If this hypothesis is true, it would result in relatively efficient numerical models of structure-borne energy in large built-up structures. Fewer parameters are required to approximate the energy solution than are required to model the characteristic wave behavior of structural vibration by using traditional displacement formulations. The energy flow hypothesis is tested in this investigation for both longitudinal vibration in rods and transverse flexural vibrations of beams. The rod is shown to behave approximately according to the thermal energy flow analogy. However, the beam solutions behave significantly differently than predicted by the thermal analogy unless locally-space-averaged energy and power are considered. Several techniques for coupling dissimilar rods and beams are also discussed. Illustrations of the solution accuracy of the methods are included.

Wohlever, J. C.; Bernhard, R. J.

1992-01-01

189

Far from equilibrium energy flow in quantum critical systems  

E-print Network

We investigate far from equilibrium energy transport in strongly coupled quantum critical systems. Combining results from gauge-gravity duality, relativistic hydrodynamics, and quantum field theory, we argue that long-time energy transport occurs via a universal steady-state for any spatial dimensionality. This is described by a boosted thermal state. We determine the transport properties of this emergent steady state, including the average energy flow and its long-time fluctuations.

Bhaseen, M J; Lucas, Andrew; Schalm, Koenraad

2013-01-01

190

Materials and Energy Flows in the Earth Science Century  

NSDL National Science Digital Library

This USGS Circular, "Materials and Energy Flows in the Earth Science Century -- A Summary of a Workshop Held by the USGS in November 1998," takes a "thorough and holistic view of the materials flow cycle, wherein materials are tracked throughout their life cycle from extraction, through manufacturing, consumer use, reuse, recycling, and disposition." The circular ends with selected references and appendixes including a list of speakers and participants and their contact information.

191

Use DCF to save energy. [Discounted Cash Flow (DCF) program  

SciTech Connect

The Discounted Cash Flow (DCF) program is written for the TI-59 programmable calculator, and a profitability analysis can help the process engineer decide among various alternatives in an energy conservation project. The objective of the analysis is to determine the following parameters: discounted cash flow rate of return (also called earning power), present value profit (at any specified cost of capital), present value profit as a percent of the capital investment, and the payback period (undiscounted).

Doane, R.C.

1982-07-01

192

Overview of Active Flow Control at NASA Langley Research Center  

NASA Technical Reports Server (NTRS)

The paper summarizes Active Flow Control projects currently underway at the NASA Langley Research Center. Technology development is being pursued within a multidisciplinary, cooperative approach, involving the classical disciplines of fluid mechanics, structural mechanics, material science, acoustics, and stability and control theory. Complementing the companion papers in this session, the present paper will focus on projects that have the goal of extending the state-of-the-art in the measurement, prediction, and control of unsteady, nonlinear aerodynamics. Toward this goal, innovative actuators, micro and macro sensors, and control strategies are considered for high payoff flow control applications. The target payoffs are outlined within each section below. Validation of the approaches range from bench-top experiments to wind-tunnel experiments to flight tests. Obtaining correlations for future actuator and sensor designs are implicit in the discussion. The products of the demonstration projects and design tool development from the fundamental NASA R&D level technology will then be transferred to the Applied Research components within NASA, DOD, and US Industry. Keywords: active flow control, separation control, MEMS, review

Pack, L. G.; Joslin, R. D.

1998-01-01

193

Distributed Power Flow Control: Distributed Power Flow Control using Smart Wires for Energy Routing  

SciTech Connect

GENI Project: Smart Wire Grid is developing a solution for controlling power flow within the electric grid to better manage unused and overall transmission capacity. The 300,000 miles of high-voltage transmission line in the U.S. today are congested and inefficient, with only around 50% of all transmission capacity utilized at any given time. Increased consumer demand should be met in part with more efficient and an economical power flow. Smart Wire Grid’s devices clamp onto existing transmission lines and control the flow of power within—much like how internet routers help allocate bandwidth throughout the web. Smart wires could support greater use of renewable energy by providing more consistent control over how that energy is routed within the grid on a real-time basis. This would lessen the concerns surrounding the grid’s inability to effectively store intermittent energy from renewables for later use.

None

2012-04-24

194

High energy density redox flow device  

DOEpatents

Redox flow devices are described including a positive electrode current collector, a negative electrode current collector, and an ion-permeable membrane separating said positive and negative current collectors, positioned and arranged to define a positive electroactive zone and a negative electroactive zone; wherein at least one of said positive and negative electroactive zone comprises a flowable semi-solid composition comprising ion storage compound particles capable of taking up or releasing said ions during operation of the cell, and wherein the ion storage compound particles have a polydisperse size distribution in which the finest particles present in at least 5 vol % of the total volume, is at least a factor of 5 smaller than the largest particles present in at least 5 vol % of the total volume.

Chiang, Yet-Ming; Carter, William Craig; Duduta, Mihai; Limthongkul, Pimpa

2014-05-13

195

Two-phase flow in a chemically active porous medium  

E-print Network

We study the problem of the transformation of a given reactant species into an immiscible product species, as they flow through a chemically active porous medium. We derive the equation governing the evolution of the volume fraction of the species -- in a one-dimensional macroscopic description --, identify the relevant dimensionless numbers, and provide simple models for capillary pressure and relative permeabilities, which are quantities of crucial importance when tackling multiphase flows in porous media. We set the domain of validity of our models and discuss the importance of viscous coupling terms in the extended Darcy's law. We investigate numerically the steady regime and demonstrate that the spatial transformation rate of the species along the reactor is non-monotonous, as testified by the existence of an inflection point in the volume fraction profiles. We obtain the scaling of the location of this inflection point with the dimensionless lengths of the problem. Eventually, we provide key elements for optimization of the reactor.

Alexandre Darmon; Michael Benzaquen; Thomas Salez; Olivier Dauchot

2014-11-20

196

Two-phase flow in a chemically active porous medium  

NASA Astrophysics Data System (ADS)

We study the problem of the transformation of a given reactant species into an immiscible product species, as they flow through a chemically active porous medium. We derive the equation governing the evolution of the volume fraction of the species, in a one-dimensional macroscopic description, identify the relevant dimensionless numbers, and provide simple models for capillary pressure and relative permeabilities, which are quantities of crucial importance when tackling multiphase flows in porous media. We set the domain of validity of our models and discuss the importance of viscous coupling terms in the extended Darcy's law. We investigate numerically the steady regime and demonstrate that the spatial transformation rate of the species along the reactor is non-monotonous, as testified by the existence of an inflection point in the volume fraction profiles. We obtain the scaling of the location of this inflection point with the dimensionless lengths of the problem. Eventually, we provide key elements for optimization of the reactor.

Darmon, Alexandre; Benzaquen, Michael; Salez, Thomas; Dauchot, Olivier

2014-12-01

197

Activities of the Iowa Energy Policy Council in Energy Education.  

ERIC Educational Resources Information Center

This report describes the various energy education programs and projects with which the Iowa Energy Policy Council has been involved since 1976. Briefly summarized are the Council's activities in curriculum development, inservice education, energy extension, and the organization of energy-related special events. (WB)

Heiting, W. Tony

198

Enhancing solar energy collection by using curved flow technology coupled with flow in porous media: an experimental study  

Microsoft Academic Search

In this study two solar energy collectors were designed and built. To enhance the heat transfer characteristics, flow in curved channel technology is used. Porous media (with 0.1453 porosity) composed of coarse aluminum chips fill the flow channels to provide for further increase in heat transfer performance and for extra energy storage capability.Measured data were recorded water flow rates that

Nasri J Rabadi; Saed A Mismar

2003-01-01

199

Assessment of activated sludge viability with flow cytometry.  

PubMed

The aim of the study was to evaluate the applicability of fluorescent dyes and multiparameter flow cytometry for the rapid and direct viability/activity assessment of activated sludge samples taken from wastewater treatment plants. Viability and activity of the biomass were estimated respectively through cellular membrane integrity, staining with SYBR Green I and Propidium Iodide, and through fluorogenic dyes capable of detecting enzymatic activity, as FDA and BCECF-AM. A procedure has been developed to disaggregate sludge flocs before dyes staining and cytometric analysis. The developed procedure allows a high recovery of bacteria with good accuracy and repeatability, and minimize the damage of the cells suspension obtained from the disaggregation of the flocs. These measurements were applied to estimate the two main parameters required to define the biological activated sludge process: the endogenous decay rate and the specific growth rate in exponential phase with high F/M ratio. Oxygen utilization rate measurements (OUR) were conducted to conventionally monitor the activity of the biomass. The preliminary data are encouraging and support the possibility to investigate bacteria dynamics on wastewater treatment plants. PMID:11827352

Ziglio, Giuliano; Andreottola, Gianni; Barbesti, Silvia; Boschetti, Giorgio; Bruni, Laura; Foladori, Paola; Villa, Roberta

2002-01-01

200

Snapshot of Active Flow Control Research at NASA Langley  

NASA Technical Reports Server (NTRS)

NASA Langley is aggressively investigating the potential advantages of active flow control as opposed to more traditional aerodynamic techniques. Many of these techniques will be blended with advanced materials and structures to further enhance payoff. Therefore a multi-disciplinary approach to technology development is being attempted that includes researchers from the more historical disciplines of fluid mechanics. acoustics, material science, structural mechanics, and control theory. The overall goals of the topics presented are focused on advancing the state of knowledge and understanding of controllable fundamental mechanisms in fluids rather than on specific engineering problems. An organizational view of current research activities at NASA Langley in active flow control as supported by several programs such as the Morphing Project under Breakthrough Vehicle Technologies Program (BVT). the Ultra-Efficient Engine Technology Program (UEET), and the 21st Century Aircraft Technology Program (TCAT) is presented. On-center research as well as NASA Langley funded contracts and grants are discussed at a relatively high level. The products of this research, as part of the fundamental NASA R and D (research and development) program. will be demonstrated as either bench-top experiments, wind-tunnel investigations, or in flight tests. Later they will be transferred to more applied research programs within NASA, DOD (Department of Defense), and U.S. industry.

Washburn, A. E.; Gorton, S. Althoff; Anders, S. G.

2002-01-01

201

Vibrational energy flow models for the Rayleigh-Love and Rayleigh-Bishop rods  

NASA Astrophysics Data System (ADS)

Energy Flow Analysis (EFA) has been developed to predict the vibrational energy density of the system structures in the medium-to-high frequency range. The elementary longitudinal wave theory is often used to describe the longitudinal vibration of a slender rod. However, for relatively large diameter rods or high frequency ranges, the elementary longitudinal wave theory is inaccurate because the lateral motions are not taken into account. In this paper, vibrational energy flow models are developed to analyze the longitudinally vibrating Rayleigh-Love rod considering the effect of lateral inertia, and the Rayleigh-Bishop rod considering the effect not only of the lateral inertia but also of the shear stiffness. The derived energy governing equations are second-order differential equations which predict the time and space averaged energy density and active intensity distributions in a rod. To verify the accuracy of the developed energy flow models, various numerical analyses are performed for a rod and coupled rods. Also, the EFA results for the Rayleigh-Love and Rayleigh-Bishop rods are compared with the analytical solutions for these models, the traditional energy flow solutions, and the analytical solutions for the classical rod.

Han, Ju-Bum; Hong, Suk-Yoon; Song, Jee-Hun; Kwon, Hyun-Wung

2014-01-01

202

U.S. energy flow - 1993  

SciTech Connect

With continued improvement in the economic health of the nation, energy consumption in 1993 increased by almost 2.5%. Use of energy in all major end-use sectors increased, with the largest gains registered in the residential/commercial sector. In this sector, substantial increase in the use of natural gas reflected a harsh 1993-1994 winter as well as broader availability of the fuel for space heating. Crude oil imports rose 8% but stood below the all-time high set in 1977. About half of the increase reflected declining domestic oil production. Imports of natural gas, principally from Canada, increased as they have every year since 1986. They comprise 11% of supply and supplement domestic production, which has similarly risen over the same time span. Increased demand for natural gas is evident in most sectors but especially in the industrial sector, where a growing number of cogenerators of electricity burn natural gas. Although coal consumption in the United States rose 3% in 1993, domestic coal production declined by a greater margin due to a coal strike. Because of increased international competition, exports fell 27%. Electricity transmitted by the utilities again increased, following a decade-long trend interrupted only in 1992 by the national economic recession. The provisions of the Energy Policy Act of 1992 dealing with transport of nonutility-generated electricity by the public utilities began to be implemented in 1993. The provisions of the Energy Policy Act as well as those of the Public Utility Regulatory Policies Act of 1978 are setting the stage for increased competition for customers and for what promises to be a restructuring of the historically monopolistic industry. Nuclear power from the United States`s 109 operable reactors constituted 21% of utility-generated electricity. With the continued retirement of outmoded and flawed reactors, nuclear capacity factors attained 71 in 1993, up from 56% a decade earlier.

Borg, I.Y.; Briggs, C.K.

1994-10-01

203

Boeing active flow control system (BAFCS)-III  

NASA Astrophysics Data System (ADS)

The Boeing Active Flow Control (AFC) System is a DARPA sponsored program to develop AFC technology to achieve a significant increase in payload and/or range for rotorcraft applications such as the V-22 tiltrotor vehicle. The program includes Computational Fluid Dynamics analysis, 0.1 scale wind tunnel and 3D testing and development of smart material based AFC actuators. This paper will provide an overview of the program, concentrating on the development and testing of the AFC actuators, and is an update of references to 1 to 3.

Jacot, A. Dean; Calkins, Frederick T.; Smith, Josef

2002-07-01

204

Groundwater Flow Demonstration Model Activities for Grades 6-12  

NSDL National Science Digital Library

This set of activities is designed to use a demonstration model available through the Uath County Cooperative Extension Services or from Project WET. They demonstrate such concepts as aquifers, groundwater flow, water table, the relationship between groundwater and surface water, recharge, and others. A glossary and standards correlations to the Utah Core Curriculum for Science are included. The physical model can be obtained through the Utah County Cooperative Extension Service, the Utah Water Resources Education Program, or for sale from Project WET (Water Education for Teachers).

Kitt Farrell-Poe

205

Sulphur-impregnated flow cathode to enable high-energy-density lithium flow batteries  

NASA Astrophysics Data System (ADS)

Redox flow batteries are promising technologies for large-scale electricity storage, but have been suffering from low energy density and low volumetric capacity. Here we report a flow cathode that exploits highly concentrated sulphur-impregnated carbon composite, to achieve a catholyte volumetric capacity 294?Ah?l?1 with long cycle life (>100 cycles), high columbic efficiency (>90%, 100 cycles) and high energy efficiency (>80%, 100 cycles). The demonstrated catholyte volumetric capacity is five times higher than the all-vanadium flow batteries (60?Ah?l?1) and 3–6 times higher than the demonstrated lithium-polysulphide approaches (50–117?Ah?l?1). Pseudo-in situ impedance and microscopy characterizations reveal superior electrochemical and morphological reversibility of the sulphur redox reactions. Our approach of exploiting sulphur-impregnated carbon composite in the flow cathode creates effective interfaces between the insulating sulphur and conductive carbon-percolating network and offers a promising direction to develop high-energy-density flow batteries.

Chen, Hongning; Zou, Qingli; Liang, Zhuojian; Liu, Hao; Li, Quan; Lu, Yi-Chun

2015-01-01

206

Pigouvian Taxation of Energy for Flow and Stock Externalities and Strategic, Noncompetitive Energy Pricing  

Microsoft Academic Search

The literature on energy and carbon taxes is by and large concerned about the derivation of (globally) efficient strategies. In contrast, this paper considers the dynamic interactions between cartelized energy suppliers and a consumers' government that collectively taxes energy carriers for Pigouvian motives. Two different kinds of external costs are associated with energy consumption: flow (e.g., acid rain) and stock

Wirl Franz

1994-01-01

207

Energy flow and ecosystem dynamics and wood energy in forest ecosystems  

E-print Network

Energy flow and ecosystem dynamics and wood energy in forest ecosystems S.M.C.U.P. Subasinghe is the absorption and the reflection of the energy by the air molecules and clouds in the atmosphere. Only 35 from soil through the root system. Within the chlorophyll pigments, the energy is fixed as carbon

208

Flow of Energy and Matter: Photosynthesis  

NSDL National Science Digital Library

In this chapter, the authors explore the misconception that carbon from carbon dioxide is the source of a plant's mass. They also look at other common, research-identified misconceptions that make it difficult for students to understand photosynthesis and to connect the photosynthetic processes in a plant cell to the plant and its surroundings. They focus on photosynthesis as a mechanism for harnessing energy and generating organic carbon from atmospheric carbon. In addition, they briefly discuss what happens to that carbon in the plant once photosynthesis is complete and gas exchange in plants during respiration. This free selection includes the Table of Contents, Introduction, and Index.

Susan Koba with Anne Tweed

2009-05-01

209

Energy flow in an arctic aquatic ecosystem  

SciTech Connect

This component of the terrestrial-aquatic interaction group seeks to use the natural stable carbon isotope ratios and radiocarbon abundances to trace the movement of photosynthate from the terrestrial environment to the stream system at MS-117. In addition to estimating the total flux, we will also attempt to describe the relative fractions derived from modern primary production and that derived from delayed inputs of eroded peat. We will also seek to determine the coupling efficiency of these energy sources to the invertebrate faunal populations in the tundra soils and streams.

Schell, D.M.

1983-01-01

210

Energy flow in an arctic aquatic ecosystem  

SciTech Connect

This component of the terrestrial-aquatic interaction group seeks to use the natural stable carbon isotope ratios and radiocarbon abundances to trace the movement of photosynthate from the terrestrial environment to the stream system at MS-117. In addition to estimating the total flux, we will also attempt to describe the relative fractions derived from modern primary production and that derived from delayed inputs of eroded peat. We will also seek to determine the coupling efficiency of these energy sources to the invertebrate faunal populations in the tundra soils and streams.

Schell, D.M.

1983-12-31

211

A Stable Vanadium Redox-Flow Battery with High Energy Density for Large-scale Energy Storage  

SciTech Connect

Low cost, high performance redox flow batteries are highly demanded for up to multi-megawatt levels of renewable and grid energy storage. Here, we report a new vanadium redox flow battery with a significant improvement over the current technologies. This new battery utilizes a sulfate-chloride mixed solution, which is capable of dissolving more than 2.5 M vanadium or about a 70% increase in the energy storage capacity over the current vanadium sulfate system. More importantly, the new electrolyte remains stable over a wide temperature range of -5 to 60oC, potentially eliminating the need of active heat management. Its high energy density, broad operational temperature window, and excellent electrochemical performance would lead to a significant reduction in the cost of energy storage, thus accelerating its market penetration.

Li, Liyu; Kim, Soowhan; Wang, Wei; Vijayakumar, M.; Nie, Zimin; Chen, Baowei; Zhang, Jianlu; Xia, Guanguang; Hu, Jian Z.; Graff, Gordon L.; Liu, Jun; Yang, Zhenguo

2011-05-01

212

Structure of Urban Movements: Polycentric Activity and Entangled Hierarchical Flows  

PubMed Central

The spatial arrangement of urban hubs and centers and how individuals interact with these centers is a crucial problem with many applications ranging from urban planning to epidemiology. We utilize here in an unprecedented manner the large scale, real-time ‘Oyster’ card database of individual person movements in the London subway to reveal the structure and organization of the city. We show that patterns of intraurban movement are strongly heterogeneous in terms of volume, but not in terms of distance travelled, and that there is a polycentric structure composed of large flows organized around a limited number of activity centers. For smaller flows, the pattern of connections becomes richer and more complex and is not strictly hierarchical since it mixes different levels consisting of different orders of magnitude. This new understanding can shed light on the impact of new urban projects on the evolution of the polycentric configuration of a city and the dense structure of its centers and it provides an initial approach to modeling flows in an urban system. PMID:21249210

Roth, Camille; Kang, Soong Moon; Batty, Michael; Barthélemy, Marc

2011-01-01

213

Waste to Energy Time Activities  

E-print Network

:40-10:10 Presentation of Dr. Kalogirou, "Waste to Energy: An Integral Part of Worldwide Sustainable Waste Management" 10D and Post-Doctorate in waste management. She is the founder and chief Scientist of ALKEMY, a US - company materials. #12;ABSTRACT Waste to Energy: An Integral Part of Worldwide Sustainable Waste Management

214

Policy support activities Brazil Rural Energy  

E-print Network

1 Policy support activities Brazil Rural Energy Enterprise Development (B-REED) Juan Zak UNEP Risoe/7 Main outcomes from policy workshop ­ Most stakeholders agreed that small energy enterprises could play and regulations favoring the installation of off-grid renewable energy systems. #12;12 Second policy support 2

215

Flow at AGS energies a barometer for high density effects?  

E-print Network

Preliminary data on transverse energy `flow' and event asymmetries reported by the E877(814) collaborations are compared to ARC model calculations for Au+Au at full AGS beam energy. ARC triple differential cross-sections for protons and pions are presented. Proton flow is produced in ARC, with the maximum in-plane momentum about 120 MeV/c. For central events the directed momentum for pions is near zero, consistent with experiment. Pion momentum opposite to the nucleons' is evident in a peripheral sample, however, indicating that this pion `anti-flow' involves absorption by `spectator' matter. `Squeeze-out' of protons in central events at mid-rapidity is suggested by the ARC distributions.

Kahana, D E; Shuryak, E V

1996-01-01

216

Flow at AGS Energies: A Barometer for High Density Effects?  

E-print Network

Preliminary data on transverse energy `flow' and event asymmetries reported by the E877(814) collaborations are compared to ARC model calculations for Au+Au at full AGS beam energy. ARC triple differential cross-sections for protons and pions are presented. Proton flow is produced in ARC, with the maximum in-plane momentum about 120 MeV/c. For central events the directed momentum for pions is near zero, consistent with experiment. Pion momentum opposite to the nucleons' is evident in a peripheral sample, however, indicating that this pion `anti-flow' involves absorption by `spectator' matter. `Squeeze-out' of protons in central events at mid-rapidity is suggested by the ARC distributions.

D. E. Kahana; Y. Pang; E. Shuryak

1996-04-05

217

Flow cytometric analysis of crayfish haemocytes activated by lipopolysaccharides  

USGS Publications Warehouse

Lipopolysaccharides (LPS) from Gram-negative bacteria are strong stimulators of white river crayfish, Procambarus zonangulus, haemocytes in vitro. Following haemocyte treatment with LPS and with LPS from rough mutant R5 (LPS Rc) from Salmonella minnesota, flow cytometric analysis revealed a conspicuous and reproducible decrease in cell size as compared to control haemocytes. These LPS molecules also caused a reduction in haemocyte viability as assessed by flow cytometry with the fluorescent dyes calcein-AM and ethidium homodimer. The onset of cell size reduction was gradual and occurred prior to cell death. Haemocytes treated with LPS from S. minnesota without the Lipid A moiety (detoxified LPS) decreased in size without a reduction of viability. The action of LPS on crayfish haemocytes appeared to be related to the activation of the prophenoloxidase system because phenoloxidase (PO)-specific activity in the supernatants from control and detoxified LPS-treated cells was significantly lower than that from LPS and LPS-Rc treated cells (P < 0.05). Furthermore, addition of trypsin inhibitor to the LPS treatments caused noticeable delays in cell size and viability changes. These patterns of cellular activation by LPS formulations indicated that crayfish haemocytes react differently to the polysaccharide and lipid A moieties of LPS, where lipid A is cytotoxic and the polysaccharide portion is stimulatory. These effects concur with the general pattern of mammalian cell activation by LPS, thereby indicting commone innate immune recognition mechanisms to bacterial antigens between cells from mammals and invertebrates. These definitive molecular approaches used to verify and identify mechanisms of invertbrate haemocyte responses to LPS could be applied with other glycoconjugates, soluble mediators, or xenobiotic compounds.

Cardenas, W.; Dankert, J.R.; Jenkins, J.A.

2004-01-01

218

Flow cytometric analysis of crayfish haemocytes activated by lipopolysaccharides.  

PubMed

Lipopolysaccharides (LPS) from Gram-negative bacteria are strong stimulators of white river crayfish, Procambarus zonangulus, haemocytes in vitro. Following haemocyte treatment with LPS and with LPS from rough mutant R5 (LPS Rc) from Salmonella minnesota, flow cytometric analysis revealed a conspicuous and reproducible decrease in cell size as compared to control haemocytes. These LPS molecules also caused a reduction in haemocyte viability as assessed by flow cytometry with the fluorescent dyes calcein-AM and ethidium homodimer. The onset of cell size reduction was gradual and occurred prior to cell death. Haemocytes treated with LPS from S. minnesota without the Lipid A moiety (detoxified LPS) decreased in size without a reduction of viability. The action of LPS on crayfish haemocytes appeared to be related to the activation of the prophenoloxidase system because phenoloxidase (PO)-specific activity in the supernatants from control and detoxified LPS-treated cells was significantly lower than that from LPS and LPS-Rc treated cells (Pactivation by LPS formulations indicated that crayfish haemocytes react differently to the polysaccharide and lipid A moieties of LPS, where lipid A is cytotoxic and the polysaccharide portion is stimulatory. These effects concur with the general pattern of mammalian cell activation by LPS, thereby indicating common innate immune recognition mechanisms to bacterial antigens between cells from mammals and invertebrates. These definitive molecular approaches used to verify and identify mechanisms of invertebrate haemocyte responses to LPS could be applied with other glycoconjugates, soluble mediators, or xenobiotic compounds. PMID:15276602

Cárdenas, Washington; Dankert, John R; Jenkins, Jill A

2004-09-01

219

Possible use of vanadium redox-flow batteries for energy storage in small grids and stand-alone photovoltaic systems  

Microsoft Academic Search

The all-vanadium redox-flow battery is a promising candidate for load leveling and seasonal energy storage in small grids and stand-alone photovoltaic systems. The reversible cell voltage of 1.3 to 1.4V in the charged state allows the use of inexpensive active and structural materials. In this work, studies on the performance of inexpensive active materials for use in vanadium redox-flow batteries

Ludwig Joerissen; Juergen Garche; Ch. Fabjan; G. Tomazic

2004-01-01

220

Mass and energy flow in the solar chromosphere and corona  

Microsoft Academic Search

Some results of investigations into the mass and energy flow in the solar chromosphere and corona are reviewed. The objective of these investigations is the development of a physical model that will not only account for the physical conditions in the outer atmosphere of the sun but also can be applied to the study of the chromospheres and coronae of

G. L. Withbroe; R. W. Noyes

1977-01-01

221

DESY 94117 Comparison of energy flows in deep inelastic  

E-print Network

rapidity gap ZEUS Collaboration August 18, 1994 Abstract Energy flows in deep inelastic electron the ZEUS detector. A comparison is made between events with and without a large rapidity gap between in the large­rapidity­gap events com­ pared to the events without a large rapidity gap. #12; 1 Introduction

222

Energy of flows on Z2 percolation clusters  

E-print Network

for all q > 2. This extends the work of Grimmett, Kesten, and Zhang and Levin and Peres in dimensions d 3 with infinitely many edges [1]. This component is called the unique infinite cluster. Kesten proved that pc(Z2) of flows with finite q energy. Grimmett, Kesten and Zhang proved that if d 3 and p > pc(Zd ), then simple

Hoffman, Christopher

223

Periodic flow at airway bifurcations. III. Energy dissipation.  

PubMed

We measured the energy dissipation associated with large-amplitude periodic flow through airway bifurcation models. Each model consisted of a single asymmetric bifurcation with a different branching angle and area ratio, with each branch terminated into an identical elastic load. Sinusoidal volumetric oscillations were applied at the parent duct so that the upstream Reynolds number (Re) varied from 30 to 77,000 and the Womersley parameter (alpha) from 4 to 30. Pressures were measured continuously at the parent duct and at both terminals, and instantaneous branch flow rates were calculated. Time-averaged energy dissipation in the bifurcation was computed from an energy budget over a control volume integrated over a cycle and was expressed as a friction factor, F. We found that when tidal volume was small [ratio of tidal volume to resident (dead space) volume, VT/VD less than 1], F was independent of branching angle and fell with increasing alpha and VT/VD. When tidal volume was large (VT/VD greater than 1), F increased with increasing branching angle and varied less strongly with alpha and VT/VD. No simple benchmark flow represented the data well over the entire experimental range. This study demonstrates that only two nondimensional parameters, alpha and VT/VD, are necessary and are sufficient to describe time-averaged energy dissipation in a given bifurcation geometry during sinusoidal flow. PMID:2228866

Tsuda, A; Savilonis, B J; Kamm, R D; Fredberg, J J

1990-08-01

224

Visualizing Poynting vector energy flow in electric circuits  

NASA Astrophysics Data System (ADS)

According to standard Poynting vector arguments, energy in a circuit flows from the batteries to the resistors, not through the connecting wires, but through empty space between the wires. The computer simulation CircuitSurveyor helps to visualize this counterintuitive fact. The simulation also demonstrates the electric fields present near a circuit.

Morris, Noah A.; Styer, Daniel F.

2012-06-01

225

Dark energy and the quietness of the local Hubble flow  

NASA Astrophysics Data System (ADS)

The linearity and quietness of the local (<10 Mpc) Hubble flow (LHF) in view of the very clumpy local universe is a long standing puzzle in standard and in open CDM (cold dark matter) cosmogony. The question addressed in this paper is whether the antigravity component of the recently discovered dark energy can cool the velocity flow enough to provide a solution to this puzzle. We calculate the growth of matter fluctuations in a flat universe containing a fraction ?X(t0) of dark energy obeying the time independent equation of state pX=w?X. We find that dark energy can indeed cool the LHF. However the dark energy parameter values required to make the predicted velocity dispersion consistent with the observed value vrms~=40 km/s have been ruled out by other observational tests constraining the dark energy parameters w and ?X. Therefore despite the claims of recent qualitative studies, dark energy with time independent equation of state cannot by itself explain the quietness and linearity of the local Hubble flow.

Axenides, M.; Perivolaropoulos, L.

2002-06-01

226

Dark Energy and the quietness of the Local Hubble Flow  

E-print Network

The linearity and quietness of the Local ($Hubble Flow (LHF) in view of the very clumpy local universe is a long standing puzzle in standard and in open CDM cosmogony. The question addressed in this paper is whether the antigravity component of the recently discovered dark energy can cool the velocity flow enough to provide a solution to this puzzle. We calculate the growth of matter fluctuations in a flat universe containing a fraction $\\Omega_X(t_0)$ of dark energy obeying the time independent equation of state $p_X = w \\rho_X$. We find that dark energy can indeed cool the LHF. However the dark energy parameter values required to make the predicted velocity dispersion consistent with the observed value $v_{rms}\\simeq 40km/sec$ have been ruled out by other observational tests constraining the dark energy parameters $w$ and $\\Omega_X$. Therefore despite the claims of recent qualitative studies dark energy with time independent equation of state can not by itself explain the quietness and linearity of the Local Hubble Flow.

M. Axenides; L. Perivolaropoulos

2002-03-28

227

U.S. energy flow -- 1994  

SciTech Connect

Energy consumption in 1994 increased for the fourth year in a row, reaching an all-time high. It was associated with a robust economy, low inflation, and low unemployment rates. Of the populous states, California lagged substantially behind the national recovery. Consumption in all major end-use sectors reached historic highs. Transmission of electrical power by the utilities increased almost 3%. However, this understates the increase of the total amount of electricity used in the nation because the amount of electricity used ``in-house`` by a growing number of self-generators is unrecorded. Imports of both fossil fuels and electricity increased. About half of the total oil consumed was imported, with Saudi Arabia being the principal supplier. Domestic oil production continued to decline; however, the sharp decline in Alaskan production was slowed. The increase in the demand for natural gas was met by both a modest increase in domestic production and imports from Canada, which comprised 10% of supply. The residential/commercial sector is the largest single consumer of natural gas; however, use by electric generators has increased annually for the past decade. The regulated utilities increased their consumption 11% in 1994. The year was noteworthy for the US nuclear power industry. Work was halted on the last nuclear power plant under construction in the country. Because of the retirement of aged and poorly performing nuclear plants and because of improved efficiencies, the capacity factor for the remaining 109 operable plants reached a record 74%.

Borg, I.Y.; Briggs, C.K.

1995-12-01

228

Solar Energy Education. Renewable energy activities for biology  

SciTech Connect

An instructional aid for teachers is presented that will allow biology students the opportunity to learn about renewable energy sources. Some of the school activities include using leaves as collectors of solar energy, solar energy stored in wood, and a fuel value test for green and dry woods. A study of organic wastes as a source of fuel is included. (BCS)

Not Available

1982-01-01

229

Solar energy education. Renewable energy activities for general science  

SciTech Connect

Renewable energy topics are integrated with the study of general science. The literature is provided in the form of a teaching manual and includes such topics as passive solar homes, siting a home for solar energy, and wind power for the home. Other energy topics are explored through library research activities. (BCS)

Not Available

1985-01-01

230

Footpoint Separation and Evershed Flow of Active Regions  

NASA Astrophysics Data System (ADS)

The bipolar nature of active regions and sunspot groups within the Sun’s photosphere is generally attributed to the emergence of magnetic flux tubes that originate from shear and turbulent pumping at the base of the Sun’s convection zone. There is debate, however, as to exactly how well-connected active regions are to solar interior. A connection to the solar interior during the ascent of a flux tube through the convection zone is a requirement within numerical models designed to describe the observed characteristics of active regions, e.g. Joy’s law tilt and latitude emergence, however, these models also predict post-emergence behavior of sunspots that is not supported observationally (Schussler and Rempel, 1995; Fan, 2009; Toth and Gerlei, 2003). It has been suggested (Rubio et al., 2008; Schussler and Rempel, 1995) that a bipolar magnetic region might lose its connection quickly upon emergence. Using data from SDO/HMI, we examine the footpoint separation and the Evershed flow of a number of active regions over time to detect the disconnection process of a sunspot from its magnetic roots.

Norton, Aimee Ann; Jones, E. H.

2012-05-01

231

Experimental Study on Active Control of Free-Surface Flow using Synthetic Jets  

NASA Astrophysics Data System (ADS)

This paper presents an active control of free-surface flow pattern using synthetic jets. The present control system is composed of Particle Tracking Velocimetry (PTV), Neural Network computing (NN) and double synthetic jet actuators, as flow measurement method, flow estimator and flow controller, respectively. PTV is used to visualize flow pattern, then the state of captured flow pattern is estimated using NN. Double synthetic jets are connected to fluidic nozzle, from which inlet flow is injected horizontally to a test section. When they are operating under various frequency and amplitude conditions, the direction of inlet flow issuing from fluidic nozzle can be easily fluctuated, upward or downward. This system is applied to water flow with free surface in a rectangular tank having the submerged and injected fluidic inlet nozzle on the right side wall and outlet at the bottom. Two flow patterns are found to be stable in this tank system. Under one stable condition, inlet flow goes directly to outlet and clockwise circulating flow is observed in the left side of tank. Under the other one, while, inlet flow is attached directly to free surface, resulting in large counterclockwise circulating flow. Any other flow pattern is unstable and stabilized to either two stable ones. In this study, double synthetic jets stabilize the unstable flow pattern as a target flow pattern. Flow pattern can be controlled actively and automatically using flow information obtained by PTV and NN.

Ueda, Tadao; Saeki, Souichi; Aida, Nobuchika; Ogawara, Kakuji

2001-11-01

232

Active flow control over a finite wing. Part 1: Experimental investigation  

Microsoft Academic Search

The effect of active flow control, via arrays of synthetic jet actuators, on the flow field around a finite wing was investigated experimentally and numerically. In the present abstract, the experimental component is discussed. To fully and properly implement flow control, a fundamental understanding of the interaction of the synthetic jets with the three-dimensional cross flow must be possessed. The

Joshua Wood; Michael Amitay; Kenneth Jansen

2008-01-01

233

Nematomorph parasites drive energy flow through a riparian ecosystem  

USGS Publications Warehouse

Parasites are ubiquitous in natural systems and ecosystem-level effects should be proportional to the amount of biomass or energy flow altered by the parasites. Here we quantified the extent to which a manipulative parasite altered the flow of energy through a forest-stream ecosystem. In a Japanese headwater stream, camel crickets and grasshoppers (Orthoptera) were 20 times more likely to enter a stream if infected by a nematomorph parasite (Gordionus spp.), corroborating evidence that nematomorphs manipulate their hosts to seek water where the parasites emerge as free-living adults. Endangered Japanese trout (Salvelinus leucomaenis japonicus) readily ate these infected orthopterans, which due to their abundance, accounted for 60% of the annual energy intake of the trout population. Trout grew fastest in the fall, when nematomorphs were driving energy-rich orthopterans into the stream. When infected orthopterans were available, trout did not eat benthic invertebrates in proportion to their abundance, leading to the potential for cascading, indirect effects through the forest-stream ecosystem. These results provide the first quantitative evidence that a manipulative parasite can dramatically alter the flow of energy through and across ecosystems.

Sato, Takuya; Wtanabe, Katsutoshi; Kanaiwa, Minoru; Niizuma, Yasuaki; Harada, Yasushi; Lafferty, Kevin D.

2011-01-01

234

Nematomorph parasites drive energy flow through a riparian ecosystem.  

PubMed

Parasites are ubiquitous in natural systems and ecosystem-level effects should be proportional to the amount of biomass or energy flow altered by the parasites. Here we quantified the extent to which a manipulative parasite altered the flow of energy through a forest-stream ecosystem. In a Japanese headwater stream, camel crickets and grasshoppers (Orthoptera) were 20 times more likely to enter a stream if infected by a nematomorph parasite (Gordionus spp.), corroborating evidence that nematomorphs manipulate their hosts to seek water where the parasites emerge as free-living adults. Endangered Japanese trout (Salvelinus leucomaenis japonicus) readily ate these infected orthopterans, which due to their abundance, accounted for 60% of the annual energy intake of the trout population. Trout grew fastest in the fall, when nematomorphs were driving energy-rich orthopterans into the stream. When infected orthopterans were available, trout did not eat benthic invertebrates in proportion to their abundance, leading to the potential for cascading, indirect effects through the forest-stream ecosystem. These results provide the first quantitative evidence that a manipulative parasite can dramatically alter the flow of energy through and across ecosystems. PMID:21560690

Sato, Takuya; Watanabe, Katsutoshi; Kanaiwa, Minoru; Niizuma, Yasuaki; Harada, Yasushi; Lafferty, Kevin D

2011-01-01

235

Evolution of energy in flow driven by rising bubbles.  

PubMed

We investigate by direct numerical simulations the flow that rising bubbles cause in an originally quiescent fluid. We employ the Eulerian-Lagrangian method with two-way coupling and periodic boundary conditions. In order to be able to treat up to 288000 bubbles, the following approximations and simplifications had to be introduced, as done before, e.g., by Climent and Magnaudet, Phys. Rev. Lett. 82, 4827 (1999). (i) The bubbles were treated as point particles, thus (ii) disregarding the near-field interactions among them, and (iii) effective force models for the lift and the drag forces were used. In particular, the lift coefficient was assumed to be 1/2, independent of the bubble Reynolds number and the local flow field. The results suggest that large-scale motions are generated, owing to an inverse energy cascade from the small to the large scales. However, as the Taylor-Reynolds number is only in the range of 1, the corresponding scaling of the energy spectrum with an exponent of -5/3 cannot develop over a pronounced range. In the long term, the property of local energy transfer, characteristic of real turbulence, is lost and the input of energy equals the viscous dissipation at all scales. Due to the lack of strong vortices, the bubbles spread rather uniformly in the flow. The mechanism for uniform spreading is as follows. Rising bubbles induce a velocity field behind them that acts on the following bubbles. Owing to the shear, those bubbles experience a lift force, which makes them spread to the left or right, thus preventing the formation of vertical bubble clusters and therefore of efficient forcing. Indeed, when the lift is artificially put to zero in the simulations, the flow is forced much more efficiently and a more pronounced energy that accumulation at large scales (due to the inverse energy cascade) is achieved. PMID:19658604

Mazzitelli, Irene M; Lohse, Detlef

2009-06-01

236

Evolution of energy in flow driven by rising bubbles  

NASA Astrophysics Data System (ADS)

We investigate by direct numerical simulations the flow that rising bubbles cause in an originally quiescent fluid. We employ the Eulerian-Lagrangian method with two-way coupling and periodic boundary conditions. In order to be able to treat up to 288000 bubbles, the following approximations and simplifications had to be introduced, as done before, e.g., by Climent and Magnaudet, Phys. Rev. Lett. 82, 4827 (1999). (i) The bubbles were treated as point particles, thus (ii) disregarding the near-field interactions among them, and (iii) effective force models for the lift and the drag forces were used. In particular, the lift coefficient was assumed to be 1/2, independent of the bubble Reynolds number and the local flow field. The results suggest that large-scale motions are generated, owing to an inverse energy cascade from the small to the large scales. However, as the Taylor-Reynolds number is only in the range of 1, the corresponding scaling of the energy spectrum with an exponent of -5/3 cannot develop over a pronounced range. In the long term, the property of local energy transfer, characteristic of real turbulence, is lost and the input of energy equals the viscous dissipation at all scales. Due to the lack of strong vortices, the bubbles spread rather uniformly in the flow. The mechanism for uniform spreading is as follows. Rising bubbles induce a velocity field behind them that acts on the following bubbles. Owing to the shear, those bubbles experience a lift force, which makes them spread to the left or right, thus preventing the formation of vertical bubble clusters and therefore of efficient forcing. Indeed, when the lift is artificially put to zero in the simulations, the flow is forced much more efficiently and a more pronounced energy that accumulation at large scales (due to the inverse energy cascade) is achieved.

Mazzitelli, Irene M.; Lohse, Detlef

2009-06-01

237

Inhibition of the active lymph pump by flow in rat mesenteric lymphatics and thoracic duct  

NASA Technical Reports Server (NTRS)

There are only a few reports of the influence of imposed flow on an active lymph pump under conditions of controlled intraluminal pressure. Thus, the mechanisms are not clearly defined. Rat mesenteric lymphatics and thoracic ducts were isolated, cannulated and pressurized. Input and output pressures were adjusted to impose various flows. Lymphatic systolic and diastolic diameters were measured and used to determine contraction frequency and pump flow indices. Imposed flow inhibited the active lymph pump in both mesenteric lymphatics and in the thoracic duct. The active pump of the thoracic duct appeared more sensitive to flow than did the active pump of the mesenteric lymphatics. Imposed flow reduced the frequency and amplitude of the contractions and accordingly the active pump flow. Flow-induced inhibition of the active lymph pump followed two temporal patterns. The first pattern was a rapidly developing inhibition of contraction frequency. Upon imposition of flow, the contraction frequency immediately fell and then partially recovered over time during continued flow. This effect was dependent on the magnitude of imposed flow, but did not depend on the direction of flow. The effect also depended upon the rate of change in the direction of flow. The second pattern was a slowly developing reduction of the amplitude of the lymphatic contractions, which increased over time during continued flow. The inhibition of contraction amplitude was dependent on the direction of the imposed flow, but independent of the magnitude of flow. Nitric oxide was partly but not completely responsible for the influence of flow on the mesenteric lymph pump. Exposure to NO mimicked the effects of flow, and inhibition of the NO synthase by N (G)-monomethyl-L-arginine attenuated but did not completely abolish the effects of flow.

Gashev, Anatoliy A.; Davis, Michael J.; Zawieja, David C.; Delp, M. D. (Principal Investigator)

2002-01-01

238

Bidirectional control system for energy flow in solar powered flywheel  

NASA Technical Reports Server (NTRS)

An energy storage system for a spacecraft is provided which employs a solar powered flywheel arrangement including a motor/generator which, in different operating modes, drives the flywheel and is driven thereby. A control circuit, including a threshold comparator, senses the output of a solar energy converter, and when a threshold voltage is exceeded thereby indicating the availability of solar power for the spacecraft loads, activates a speed control loop including the motor/generator so as to accelerate the flywheel to a constant speed and thereby store mechanical energy, while also supplying energy from the solar converter to the loads. Under circumstances where solar energy is not available and thus the threshold voltage is not exceeded, the control circuit deactivates the speed control loop and activates a voltage control loop that provides for operation of the motor as a generator so that mechanical energy from the flywheel is converted into electrical energy for supply to the spacecraft loads.

Nola, Frank J. (inventor)

1987-01-01

239

Two-phase flow in a chemically active porous medium.  

PubMed

We study the problem of the transformation of a given reactant species into an immiscible product species, as they flow through a chemically active porous medium. We derive the equation governing the evolution of the volume fraction of the species, in a one-dimensional macroscopic description, identify the relevant dimensionless numbers, and provide simple models for capillary pressure and relative permeabilities, which are quantities of crucial importance when tackling multiphase flows in porous media. We set the domain of validity of our models and discuss the importance of viscous coupling terms in the extended Darcy's law. We investigate numerically the steady regime and demonstrate that the spatial transformation rate of the species along the reactor is non-monotonous, as testified by the existence of an inflection point in the volume fraction profiles. We obtain the scaling of the location of this inflection point with the dimensionless lengths of the problem. Eventually, we provide key elements for optimization of the reactor. PMID:25554172

Darmon, Alexandre; Benzaquen, Michael; Salez, Thomas; Dauchot, Olivier

2014-12-28

240

Flow characteristics of expansion energy used pneumatic booster  

NASA Astrophysics Data System (ADS)

The most common booster is called input pressure reduced (IPR) booster. However, this type of booster has its own shortages, such as its small output flow, when the boosting ratio is higher, the shortage becomes more distinct. Recent research on pneumatic boosters mainly focused on the factors that influence the characteristics of the boosters, some new kinds of pneumatic booster structures were designed, but the efficiency and output flow of these boosters are still not improved sufficiently. In order to improve the output flow of the pneumatic booster, a new kind of booster, expansion energy used (EEU) booster, is proposed. Non-linear differential equations of the pneumatic booster are set up. By using the software MATLAB/Simulink for simulation, the motion characteristics of the pistons, the characteristics of the output flow of the boosters are obtained for analysis of a principle. The principle, which is used to elevate the output flow of the two kinds of boosters, is that the average pressure of the air in the driving chambers of the EEU booster is higher than that of the IPR booster. The simulation and experimental research of the output flow characteristics are done. The simulation and experimental results are in a good accordance. And the simulation and experimental results show that when the air source pressure and the output pressure are set at 0.6 MPa and 0.8 MPa, respectively, with the increase of the terminal pressure of the air in the driving chamber, the output flow of the IPR booster ascends stably. As the terminal pressure of the air in the driving chamber goes up, the output flow of the EEU booster rises, and later it almost remains constant. In addition, with the same terminal pressure, the output flow of the EEU booster is greater than that of the IPR booster, and the difference decreases when the terminal pressure grows. At last, the output pressure is set at 0.8 MPa, under the optimum work state of the EEU booster, the output flow of the two kinds of boosters all declines with the rise of the boosting ratio. Furthermore, the output flow of the EEU booster is higher than that of IPR booster by 95 L/min approximately. The proposed research lays the foundation for optimistic of the EEU booster.

Shi, Yan; Cai, Maolin; Xu, Weiqing; Lü, Jie

2012-09-01

241

Incident energy dependence of hadronic activity  

SciTech Connect

Two features of high-energy hadronic cascades have been long known to shielding specialists: (a) in a high-energy hadronic cascade in a given material (incident E [approx equal] 10 GeV), the relative abundance and spectrum of each hadronic species responsible for most of the energy deposition is independent of the energy or species of the incident hadron, and (b) because [pi][sup 0] production bleeds off more and more energy into the electromagnetic sector as the energy of the incident hadron increases, the level of this low-energy activity rises less rapidly than the incident energy, and in fact rises very nearly as a power of the incident energy. Both features are of great importance in hadron calorimetry, where it is the universal spectrum'' which makes possible the definition of an intrinsic e/h, and the increasing fraction of the energy going into [pi][sup 0]'s which leads to the energy dependence of e/[pi]. We present evidence for the universal spectrum,'' and use an induction argument and simulation results to demonstrate that the low-energy activity scales as E[sup m], with 0.80 [le] m [le] 0.85.

Gabriel, T.A. (Oak Ridge National Lab., TN (United States)); Groom, D.E. (Lawrence Berkeley Lab., CA (United States)); Job, P.K. (Argonne National Lab., IL (United States)); Mokhov, N.V. (Institute of High Energy Physics, Serpukov (Russian Federation) Superconducting Super Collider Lab., Dallas, TX (United States)); Stevenson, G.R. (European Organization for Nuclear Research, Geneva (Switzerland)

1993-01-01

242

Incident energy dependence of hadronic activity  

SciTech Connect

Two features of high-energy hadronic cascades have been long known to shielding specialists: (a) in a high-energy hadronic cascade in a given material (incident E {approx_equal} 10 GeV), the relative abundance and spectrum of each hadronic species responsible for most of the energy deposition is independent of the energy or species of the incident hadron, and (b) because {pi}{sup 0} production bleeds off more and more energy into the electromagnetic sector as the energy of the incident hadron increases, the level of this low-energy activity rises less rapidly than the incident energy, and in fact rises very nearly as a power of the incident energy. Both features are of great importance in hadron calorimetry, where it is the ``universal spectrum`` which makes possible the definition of an intrinsic e/h, and the increasing fraction of the energy going into {pi}{sup 0}`s which leads to the energy dependence of e/{pi}. We present evidence for the ``universal spectrum,`` and use an induction argument and simulation results to demonstrate that the low-energy activity scales as E{sup m}, with 0.80 {le} m {le} 0.85.

Gabriel, T.A. [Oak Ridge National Lab., TN (United States); Groom, D.E. [Lawrence Berkeley Lab., CA (United States); Job, P.K. [Argonne National Lab., IL (United States); Mokhov, N.V. [Institute of High Energy Physics, Serpukov (Russian Federation)]|[Superconducting Super Collider Lab., Dallas, TX (United States); Stevenson, G.R. [European Organization for Nuclear Research, Geneva (Switzerland)

1993-03-01

243

Lithium-Based High Energy Density Flow Batteries  

NASA Technical Reports Server (NTRS)

Systems and methods in accordance with embodiments of the invention implement a lithium-based high energy density flow battery. In one embodiment, a lithium-based high energy density flow battery includes a first anodic conductive solution that includes a lithium polyaromatic hydrocarbon complex dissolved in a solvent, a second cathodic conductive solution that includes a cathodic complex dissolved in a solvent, a solid lithium ion conductor disposed so as to separate the first solution from the second solution, such that the first conductive solution, the second conductive solution, and the solid lithium ionic conductor define a circuit, where when the circuit is closed, lithium from the lithium polyaromatic hydrocarbon complex in the first conductive solution dissociates from the lithium polyaromatic hydrocarbon complex, migrates through the solid lithium ionic conductor, and associates with the cathodic complex of the second conductive solution, and a current is generated.

Bugga, Ratnakumar V. (Inventor); West, William C. (Inventor); Kindler, Andrew (Inventor); Smart, Marshall C. (Inventor)

2014-01-01

244

The energy flow of discrete extended gradient systems  

NASA Astrophysics Data System (ADS)

We study the energy flow of spatially discrete, extended gradient systems (infinite lattices), allowing the total energy to be infinite and considering formally gradient dynamics. We show that in spatial dimensions 1,2, the flow is for almost all times arbitrarily close to the set of equilibria, and in dimensions ?3, the size of the set with non-equilibrium dynamics for a positive density of times is two dimensions less than the space dimension. The theory applies to first- and second-order dynamics of elastic chains in a periodic or polynomial potential, chains with interactions beyond the nearest neighbour, deterministic dynamics of spin glasses, the discrete complex Ginzburg-Landau equation, and others. In particular, we apply the theory to show the existence of coarsening dynamics for a class of generalized Frenkel-Kontorova models in bistable potential.

Slijep?evi?, Siniša

2013-07-01

245

Ruthenium based redox flow battery for solar energy storage  

Microsoft Academic Search

The technical performance for the operation of a stand alone redox flow battery system for solar energy storage is presented. An undivided reactor configuration has been employed along with porous graphite felt electrodes and ruthenium acetylacetonate as electrolyte in acetonitrile solvent. Limiting current densities are determined for concentrations of 0.02M and 0.1M ruthenium acetylacetonate. Based on these, operating conditions for

Mohammed Harun Chakrabarti; Edward Pelham Lindfield Roberts; Chulheung Bae; Muhammad Saleem

2011-01-01

246

OWC wave energy devices with air flow control  

Microsoft Academic Search

A theoretical model is developed to simulate the energy conversion, from wave to turbine shaft, of an oscillating-water-column (OWC) plant equipped with a Wells air-turbine and with a valve (in series or in parallel with the turbine) for air-flow control. Numerical simulations show that the use of a control valve, by preventing or reducing the aerodynamic stall losses at the

A. F. de O. Falcão; P. A. P. Justino

1999-01-01

247

Characterization of cerebral blood oxygenation and flow changes during prolonged brain activation  

Microsoft Academic Search

The behavior of cerebral blood flow and oxygenation during prolonged brain activation was studied using magnetic resonance imaging (MRI) sensitized to flow and oxygenation changes, as well as positron emission tomography sensitized toflow. Neuronal habituation effects and hemodynamic changes were evaluated across tasks and cortical regions. Nine types of activation stimuli or tasks, including motor activation, vibrotactile stimulation, and several

P. A. Bandettini; K. K. Kwong; T. L. Davis; R. B. H. Tootell; E. C. Wong; P. T. Fox; J. W. Belliveau; R. M. Weisskoff; B. R. Rosen

1997-01-01

248

Advanced Redox Flow Batteries for Stationary Electrical Energy Storage  

SciTech Connect

This report describes the status of the advanced redox flow battery research being performed at Pacific Northwest National Laboratories for the U.S. Department of Energy’s Energy Storage Systems Program. The Quarter 1 of FY2012 Milestone was completed on time. The milestone entails completion of evaluation and optimization of single cell components for the two advanced redox flow battery electrolyte chemistries recently developed at the lab, the all vanadium (V) mixed acid and V-Fe mixed acid solutions. All the single cell components to be used in future kW-scale stacks have been identified and optimized in this quarter, which include solution electrolyte, membrane or separator; carbon felt electrode and bi-polar plate. Varied electrochemical, chemical and physical evaluations were carried out to assist the component screening and optimization. The mechanisms of the battery capacity fading behavior for the all vanadium redox flow and the Fe/V battery were discovered, which allowed us to optimize the related cell operation parameters and continuously operate the system for more than three months without any capacity decay.

Li, Liyu; Kim, Soowhan; Xia, Guanguang; Wang, Wei; Yang, Zhenguo

2012-03-19

249

Energy and Color Flow in Dijet Rapidity Gaps  

E-print Network

When rapidity gaps in high-$p_T$ dijet events are identified by energy flow in the central region, they may be calculated from factorized cross sections in perturbative QCD, up to corrections that behave as inverse powers of the central region energy. Although power-suppressed corrections may be important, a perturbative calculation of dijet rapidity gaps in ${\\rm p}\\bar{\\rm p}$ scattering successfully reproduces the overall features observed at the Tevatron. In this formulation, the average color content of the hard scattering is well-defined. We find that hard dijet rapidity gaps in quark-antiquark scattering are not due to singlet exchange alone.

Oderda, G; Oderda, Gianluca; Sterman, George

1998-01-01

250

A review on flow energy harvesters based on flapping foils  

NASA Astrophysics Data System (ADS)

This article presents an overview of the state of the art investigations on the recently developed oscillating foil energy converters. A summary of available knowledge and up-to-date progress in the application of such bio-inspired systems for renewable energy devices is provided. Starting from concepts and achieved results in three distinguishable categories, various parametric studies are reviewed, along with an in-depth discussion on the potential device performance enhancement via flow control mechanisms. Finally, potential future research directions are discussed.

Xiao, Qing; Zhu, Qiang

2014-04-01

251

Energy and Color Flow in Dijet Rapidity Gaps  

E-print Network

When rapidity gaps in high-$p_T$ dijet events are identified by energy flow in the central region, they may be calculated from factorized cross sections in perturbative QCD, up to corrections that behave as inverse powers of the central region energy. Although power-suppressed corrections may be important, a perturbative calculation of dijet rapidity gaps in ${\\rm p}\\bar{\\rm p}$ scattering successfully reproduces the overall features observed at the Tevatron. In this formulation, the average color content of the hard scattering is well-defined. We find that hard dijet rapidity gaps in quark-antiquark scattering are not due to singlet exchange alone.

Gianluca Oderda; George Sterman

1998-06-30

252

Wave turbulence revisited: Where does the energy flow?  

E-print Network

Turbulence in a system of nonlinearly interacting waves is referred to as wave turbulence. It has been known since seminal work by Kolmogorov, that turbulent dynamics is controlled by a directional energy flux through the wavelength scales. We demonstrate that an energy cascade in wave turbulence can be bi-directional, that is, can simultaneously flow towards large and small wavelength scales from the pumping scales at which it is injected. This observation is in sharp contrast to existing experiments and wave turbulence theory where the energy flux only flows in one direction. We demonstrate that the bi-directional energy cascade changes the energy budget in the system and leads to formation of large-scale, large-amplitude waves similar to oceanic rogue waves. To study surface wave turbulence, we took advantage of capillary waves on a free, weakly charged surface of superfluid helium He-II at temperature 1.7K. Although He-II demonstrates non-classical thermomechanical effects and quantized vorticity, waves on its surface are identical to those on a classical Newtonian fluid with extremely low viscosity. The possibility of directly driving a charged surface by an oscillating electric field and the low viscosity of He-II have allowed us to isolate the surface dynamics and study nonlinear surface waves in a range of frequencies much wider than in experiments with classical fluids.

L. V. Abdurakhimov; I. A. Remizov; A. A. Levchenko; G. V. Kolmakov; Y. V. Lvov

2014-04-03

253

Passive and Active Flow Control by Swimming Fishes and Mammals  

E-print Network

2004). Aquatic animals (e.g., fishes, whales, seals, penguins) produce hydrodynamic thrust velocimetry, flukes, biomechanics, hydrodynamics, biomimetic Abstract What mechanisms of flow control do animals use to enhance hydrodynamic perfor- mance? Animals are capable of manipulating flow around

Fish, Frank

254

Active control of tip clearance flow in axial compressors  

E-print Network

Control of compressor tip clearance flows is explored in a linear cascade using three types of fluidic actuators; Normal Synthetic Jet (NSJ; unsteady jet normal to the mean flow with zero net mass flux), Directed Synthetic ...

Bae, Jinwoo W

2001-01-01

255

An overview of active flow control actuators and applications (presentation video)  

NASA Astrophysics Data System (ADS)

Active Flow Control (AFC) is an emerging technology which promises performance enhancements to both military and civilian aircraft. A technique which uses energy input at discrete locations to manipulate the flow over an aerodynamic surface, AFC may be used to reduce drag, prevent flow separation, and enable otherwise-infeasible aerodynamic designs. Additional applications include shear layer and turbulence control for aero-optics applications and mixing enhancement for thermal applications. Many AFC applications call for a high frequency fluidic perturbation provided by an electrically-powered actuator. In these instances, piezoelectric (PZT) materials have served as the workhorse for flow control actuators, such as the widely-studied synthetic jet. Because the PZT materials form the critical component of the actuator, the maximum performance of the synthetic jet (velocity and momentum output) is limited by the physical limitations of the PZT material. The purpose of this presentation is to provide a high level overview of AFC actuators and applications in an attempt to engage the smart materials community and encourage advanced material development in support of these crucial applications.

Brzozowski, Daniel; Whalen, Edward A.

2014-04-01

256

The Flow of Energy: Primary Production to Higher Trophic Levels  

NSDL National Science Digital Library

Today we will explore some of the multiple topics related to the flow of energy in ecosystems. Energy is used up and lost as heat as it moves through ecosystems, and new energy is continually added to the earth in the form of solar radiation. As we learned in the last lecture, the earth is an open system in regard to energy.Nutrients and other materials, on the other hand, are continually recirculated within and among ecosystems, and by and large there are no new inputs or losses from the planet. In terms of materials, then, the earth is a closed system. Both energy and materials are essential to ecosystem structure, function, and composition. You have already been exposed to the basic concepts of nutrient cycles; in this lecture we focus on energy. Note that in terms of the cycling of carbon, "materials" and energy can be inter-converted. For example, we know how many calories (a measure of energy) a gram of certain carbon compounds materials such as fats or carbohydrates contain.

Klink, George

257

Irreducible Representations Of Oscillatory And Swirling Flows In Active Soft Matter  

E-print Network

Recent experiments imaging fluid flow around swimming microorganisms have revealed complex time-dependent velocity fields that differ qualitatively from the stresslet flow commonly employed in theoretical descriptions of active matter. Here we obtain the most general flow around a finite sized active particle by expanding the surface stress in irreducible Cartesian tensors. This expansion, whose first term is the stresslet, must include, respectively, third-rank polar and axial tensors to minimally capture crucial features of the active oscillatory flow around translating Chlamydomonas and the active swirling flow around rotating Volvox. The representation provides explicit expressions for the irreducible symmetric, antisymmetric and isotropic parts of the continuum active stress. Antisymmetric active stresses do not conserve orbital angular momentum and our work thus shows that spin angular momentum is necessary to restore angular momentum conservation in continuum hydrodynamic descriptions of active soft matter.

Somdeb Ghose; R. Adhikari

2014-08-05

258

Irreducible representations of oscillatory and swirling flows in active soft matter.  

PubMed

Recent experiments imaging fluid flow around swimming microorganisms have revealed complex time-dependent velocity fields that differ qualitatively from the stresslet flow commonly employed in theoretical descriptions of active matter. Here we obtain the most general flow around a finite sized active particle by expanding the surface stress in irreducible Cartesian tensors. This expansion, whose first term is the stresslet, must include, respectively, third-rank polar and axial tensors to minimally capture crucial features of the active oscillatory flow around translating Chlamydomonas and the active swirling flow around rotating Volvox. The representation provides explicit expressions for the irreducible symmetric, antisymmetric, and isotropic parts of the continuum active stress. Antisymmetric active stresses do not conserve orbital angular momentum and our work thus shows that spin angular momentum is necessary to restore angular momentum conservation in continuum hydrodynamic descriptions of active soft matter. PMID:24702422

Ghose, Somdeb; Adhikari, R

2014-03-21

259

Blended Wing Body Systems Studies: Boundary Layer Ingestion Inlets With Active Flow Control  

NASA Technical Reports Server (NTRS)

A CFD analysis was performed on a Blended Wing Body (BWB) aircraft with advanced, turbofan engines analyzing various inlet configurations atop the aft end of the aircraft. The results are presented showing that the optimal design for best aircraft fuel efficiency would be a configuration with a partially buried engine, short offset diffuser using active flow control, and a D-shaped inlet duct that partially ingests the boundary layer air in flight. The CFD models showed that if active flow control technology can be satisfactorily developed, it might be able to control the inlet flow distortion to the engine fan face and reduce the powerplant performance losses to an acceptable level. The weight and surface area drag benefits of a partially submerged engine shows that it might offset the penalties of ingesting the low energy boundary layer air. The combined airplane performance of such a design might deliver approximately 5.5% better aircraft fuel efficiency over a conventionally designed, pod-mounted engine.

Geiselhart, Karl A. (Technical Monitor); Daggett, David L.; Kawai, Ron; Friedman, Doug

2003-01-01

260

Energy dissipation of debris flow through pile group obstructions  

NASA Astrophysics Data System (ADS)

Since the devastating Sichuan Earthquake on May 12, 2008, large-scale landslides and debris flows are predicted to occur in these populous areas over the next 10-30 years. In order to prevent and mitigate the geological disasters, it is of great importance to better understand the mechanism of granular flows and to predict their temporal and spatial scales in an efficient way. In this work, we develop a Roe-type finite volume model of the Savage-Hutter equations. Unstructured grid of either triangular or quadrilateral cells is used to match natural topography wells. After appropriately selecting bed and internal friction coefficients, we conduct a series of numerical flume experiments to simulate debris flow passing through pile group obstruction, which is commonly used in damping the kinetic energy of debris flows. Pile group of different spatial patterns are decorated in the downstream of the flume, and the influences of the spatial distributions of pile group obstruction to their damping effect are investigated.

Fei, Minglong; Sun, Qicheng; Zhong, Deyu; Zhou, Gordon G. D.

2013-06-01

261

Signal averaged laser Doppler measurements of activation–flow coupling in the rat forepaw somatosensory cortex  

Microsoft Academic Search

Regional alterations in cerebral blood flow (CBF) are widely used as a surrogate for neuronal function based on an intact coupling between changes in regional CBF and metabolism, activation–flow coupling (AFC). To further investigate parameters affecting AFC, we have implemented a rat model with electrical forepaw stimulation under ?-chloralose anesthesia using laser Doppler (LD) measurements of flow parameters through thinned

John A Detre; Beau M Ances; Kazushi Takahashi; Joel H Greenberg

1998-01-01

262

Dimensions of Flow in Academic and Social Activities among Summer Music Camp participants  

ERIC Educational Resources Information Center

The purpose of this study was to investigate the occurrence of flow experiences among high school music students attending a two-week summer instrumental music camp. Specifically, the study sought to determine if: (1) students do indeed experience flow in summer camp settings; (2) what activities are conducive to flow; (3) what is the relationship…

Diaz, Frank M.; Silveira, Jason M.

2013-01-01

263

Optimal active power flow incorporating FACTS devices with power flow control constraints  

Microsoft Academic Search

An improved two-stage approach to solving the new formulation of optimal power flow (OPF) problem which incorporates flexible AC transmission system (FACTS) devices and power flow control constraints is presented. This approach is shown to provide an enhanced economic solution with the use of controllable FACTS devices. The FACTS devices considered include series compensators and phase shifters. The power flow

G. Shaoyun; T. S. Chung

1998-01-01

264

Search for active lava flows with VIRTIS on Venus Express  

NASA Astrophysics Data System (ADS)

There are several lines of evidence suggesting that effusive volcanism still shapes the surface of Venus but the rate is not well constrained. The preservation of impact craters is consistent with a rate of 1 km3/year (comparable to Earth intraplate volcanism) as well as a rate several orders of magnitude less. It has been proposed to search images of the Venus nightside near 1 ?m for the excess thermal emission of active lava flows. The scattering of photons in the optically thick cloud cover is similar in effect to a Gaussian blur with a Full Width Half Maximum (FWHM) of 90 km. This reduces the maximum intensity of the anomalies introduced by eruptions, making detection more difficult than in a clear atmosphere, but also provides larger targets for imaging. The VIRTIS instrument on Venus Express observed surface thermal emission at 1.02 ?m wavelength between April 2006 and October 2008 at a spatial resolution of typically a few tens of km. We have searched the ~1000 images for the signatures of active lava flows in form of transient excess emission measured in several adjacent pixels. We estimate that eruptions with 1GW/?m/sr total excess specific thermal emission would be clearly visible compared to the instrumental and atmospheric noise but no such anomalies were detected. It has been shown that the total thermal emission of eruptions on Earth can be related to the lava discharge rate. We adjust this model to the Venus surface environment by adjusting observed lava surface temperature distributions and estimate that a discharge rate on the order of 1000 m3/s is required to produce an anomaly clearly identifiable in VIRTIS data. This is a relatively high value for effusive volcanism but a few historical eruptions on Earth surpassed it. Adopting a fit to the discharge rates of historical eruptions on Hawaii as a model, 4% to 10% of the eruptions in the field of view of VIRTIS images would have been detectable. In addition to the low detection probability, the low surface coverage of on average 1% of the surface per day over a period of 800 days indicates that the probability of an eruption imaged by VIRTIS was low to begin with. Therefore the VIRTIS data set fails to provide a useful constraint on the rate of volcanism on Venus. Venus Express continues to observe surface thermal emission with the Venus Monitoring camera. For future missions, near infrared imaging would profit from more frequent images of the same area than is possible from the excentric 24h orbit of Venus Express. The superrotation of the cloud cover allows to reduce atmospheric noise by averaging of images taken hours apart and the detection of eruptions with 100 m3/s lava or less might then be possible. Nevertheless, searching for lava flows emplaced between two observations of the same surface by high resolution radar imaging, altimetry or interferometry generally provides a better constraints than infrared imaging for the same observation duration and surface coverage. However, high resolution radar and low resolution infrared observations are highly complementary and could be accommodated on the same mission, preferably with a low circular polar orbit.

Mueller, N. T.; Helbert, J.; Stofan, E. R.; Smrekar, S. E.; Piccioni, G.; Drossart, P.

2012-12-01

265

An Energy Principle for Ideal MHD Equilibria with Flows  

SciTech Connect

In the standard ideal MHD energy principle for equilibria with no flows, the stability criterion, which is the defi niteness of the perturbed potential energy, is usually constructed from the linearized equation of motion. Equivalently while more straightforwardly, it can also be obtained from the second variation of the Hamiltonian calculated with proper constraints. For equilibria with flows, a stability criterion was proposed from the linearized equation of motion, but not explained as an energy principle1. In this paper, the second variation of the Hamiltonian is found to provide a stability criterion equivalent to, while more straightforward than, what was constructed from the linearized equation of motion. To calculate the variations of the Hamiltonian, a complete set of constraints on the dynamics of the perturbations is derived from the Euler-Poincare structure of the ideal MHD. In addition, a previous calculation of the second variation of the Hamiltonian was claimed to give a different stability criterion2, and in this paper we argue such a claim is incorrect.

Yao Zhou and Hong Qin

2013-03-11

266

Giant Volume Change of Active Gels under Continuous Flow Ye Zhang,,  

E-print Network

Giant Volume Change of Active Gels under Continuous Flow Ye Zhang,,§ Ning Zhou,,§ Ning Li, Megan reactions. Here we show that a continuous flow of reactant solution leads to by far the largest volume oscillating volume changes in spontaneously active gels for chemomechanical transduction. Conversion

Epstein, Irving R.

267

A MICROCHIP FOR CONTINUOUS-FLOW MAG-NETIC-ACTIVATED INCUBATION AND SEPARA-  

E-print Network

A MICROCHIP FOR CONTINUOUS-FLOW MAG- NETIC-ACTIVATED INCUBATION AND SEPARA- TION OF MICROPARTICLES This paper presents a novel microfluidic chip that exploits magnetic manipula- tion for integrated incubation and separation of microparticles in continuous flow. The chip integrates an active-mixing enhanced incubator

Lin, Qiao

268

The evolution of an active silicic lava flow field: an ETM+ perspective  

Microsoft Academic Search

An active dacitic lava flow began advancing down the south flank of the Caliente dome unit (Santiaguito Volcano, Guatemala) during July 1999. By January 2002 continued activity had built a ?1-km2, 66×106 m3 flow field. Using a time series of Landsat 7 ETM+ images and field observations the evolution and characteristics of this flow field are described. Throughout the period

Andrew J. L Harris; Luke P Flynn; Otoniel Matias; William I Rose; Julio Cornejo

2004-01-01

269

Energy Focusing in a Converging Fluid Flow: Implications for Sonoluminescence  

SciTech Connect

Cavitation induced by a converging flow leads to such a powerful concentration of energy that subnanosecond flashes of light with an ultraviolet spectrum are emitted. Light intensity is enhanced a factor of 5000 by using xenon rather than helium. This xenon enhancement is similar to that seen with surface bubbles and acoustically driven bubbles in nonaqueous fluids, but contrasts with acoustically driven bubbles in water where xenon is only 5thinspthinsptimes brighter than helium. This system has been studied with the goals of obtaining sonoluminescence from diatomic gases and learning about those aspects of sonoluminescence which are properties of a single collapse. {copyright} {ital 1999} {ital The American Physical Society}

Weninger, K.R.; Camara, C.G.; Putterman, S.J. [Physics Department, University of California, Los Angeles, California 90095 (United States)] [Physics Department, University of California, Los Angeles, California 90095 (United States)

1999-09-01

270

Variational energy principle for compressible, baroclinic flow. 2: Free-energy form of Hamilton's principle  

NASA Technical Reports Server (NTRS)

The first and second variations are calculated for the irreducible form of Hamilton's Principle that involves the minimum number of dependent variables necessary to describe the kinetmatics and thermodynamics of inviscid, compressible, baroclinic flow in a specified gravitational field. The form of the second variation shows that, in the neighborhood of a stationary point that corresponds to physically stable flow, the action integral is a complex saddle surface in parameter space. There exists a form of Hamilton's Principle for which a direct solution of a flow problem is possible. This second form is related to the first by a Friedrichs transformation of the thermodynamic variables. This introduces an extra dependent variable, but the first and second variations are shown to have direct physical significance, namely they are equal to the free energy of fluctuations about the equilibrium flow that satisfies the equations of motion. If this equilibrium flow is physically stable, and if a very weak second order integral constraint on the correlation between the fluctuations of otherwise independent variables is satisfied, then the second variation of the action integral for this free energy form of Hamilton's Principle is positive-definite, so the action integral is a minimum, and can serve as the basis for a direct trail and error solution. The second order integral constraint states that the unavailable energy must be maximum at equilibrium, i.e. the fluctuations must be so correlated as to produce a second order decrease in the total unavailable energy.

Schmid, L. A.

1977-01-01

271

Active power filter with hybrid energy storage  

Microsoft Academic Search

An active power filter that uses an impressed current converter and an inductive-capacitive energy storage circuit is presented. This storage includes a switching section to interface the inductive and capacitive element. This solution allows independent choice of the converter configuration and of the type of storage system which, in this particular case, is mainly capacitive. The theory of operation is

L. Malesani; L. Rossetto; P. Tenti

1991-01-01

272

Energy Activities for Junior High Social Studies.  

ERIC Educational Resources Information Center

The document contains seven learning activities for junior high students on the energy situation. Objectives are to help students gain understanding and knowledge about the relationships between humans and their social and physical environments; solve problems and clarify issues; examine personal beliefs and values; and recognize the relationships…

Minnesota State Energy Agency, St. Paul.

273

Implementation of electric vehicle system based on solar energy in Singapore assessment of flow batteries for energy storage  

E-print Network

For large-scale energy storage application, flow battery has the advantages of decoupled power and energy management, extended life cycles and relatively low cost of unit energy output ($/kWh). In this thesis, an overview ...

Chen, Yaliang

2009-01-01

274

The Magnetic Free Energy in Active Regions  

NASA Technical Reports Server (NTRS)

The magnetic field permeating the solar atmosphere governs much of the structure, morphology, brightness, and dynamics observed on the Sun. The magnetic field, especially in active regions, is thought to provide the power for energetic events in the solar corona, such as solar flares and Coronal Mass Ejections (CME) and is believed to energize the hot coronal plasma seen in extreme ultraviolet or X-rays. The question remains what specific aspect of the magnetic flux governs the observed variability. To directly understand the role of the magnetic field in energizing the solar corona, it is necessary to measure the free magnetic energy available in active regions. The grant now expiring has demonstrated a new and valuable technique for observing the magnetic free energy in active regions as a function of time.

Metcalf, Thomas R.; Mickey, Donald L.; LaBonte, Barry J.

2001-01-01

275

Energy flows in graphene: hot carrier dynamics and cooling.  

PubMed

Long lifetimes of hot carriers can lead to qualitatively new types of responses in materials. The magnitude and time scales for these responses reflect the mechanisms governing energy flows. We examine the microscopics of two processes which are key for energy transport, focusing on the unusual behavior arising due to graphene's unique combination of material properties. One is hot carrier generation in its photoexcitation dynamics, where hot carriers multiply through an Auger type carrier-carrier scattering cascade. The hot-carrier generation manifests itself through elevated electronic temperatures which can be accessed in a variety of ways, in particular optical conductivity measurements. Another process of high interest is electron-lattice cooling. We survey different cooling pathways and discuss the cooling bottleneck arising for the momentum-conserving electron-phonon scattering pathway. We show how this bottleneck can be relieved by higher-order collisions-supercollisions-and examine the variety of supercollision processes that can occur in graphene. PMID:25834944

Song, Justin C W; Levitov, Leonid S

2015-04-29

276

Energy Efficient Process Heating: Managing Air Flow Kevin Carpenter and Kelly Kissock  

E-print Network

Energy Efficient Process Heating: Managing Air Flow Kevin Carpenter and Kelly Kissock Department excess air flow in and out of process heating equipment. Energy saving opportunities from managing air in process heating system This paper discusses opportunities to increase efficiency by managing air flow

Kissock, Kelly

277

Flow-induced nonequilibrium self-assembly in suspensions of stiff, apolar, active filaments  

E-print Network

Active bodies in viscous fluids interact hydrodynamically through self-generated flows. Here we study spontaneous aggregation induced by hydrodynamic flow in a suspension of stiff, apolar, active filaments. Lateral hydrodynamic attractions in extensile filaments lead, independent of volume fraction, to anisotropic aggregates which translate and rotate ballistically. Lateral hydrodynamic repulsion in contractile filaments lead, with increasing volume fractions, to microstructured states of asters, clusters, and incipient gels where, in each case, filament motion is diffusive. Our results demonstrate that the interplay of active hydrodynamic flows and anisotropic excluded volume interactions provides a generic nonequilibrium mechanism for hierarchical self-assembly of active soft matter.

Ankita Pandey; P. B. Sunil Kumar; R. Adhikari

2014-08-02

278

Flow-induced nonequilibrium self-assembly in suspensions of stiff, apolar, active filaments  

E-print Network

Active bodies in viscous fluids interact hydrodynamically through self-generated flows. Here we study spontaneous aggregation induced by hydrodynamic flow in a suspension of stiff, apolar, active filaments. Lateral hydrodynamic attractions in extensile filaments lead, independent of volume fraction, to anisotropic aggregates which translate and rotate ballistically. Lateral hydrodynamic repulsion in contractile filaments lead, with increasing volume fractions, to microstructured states of asters, clusters, and incipient gels where, in each case, filament motion is diffusive. Our results demonstrate that the interplay of active hydrodynamic flows and anisotropic excluded volume interactions provides a generic nonequilibrium mechanism for hierarchical self-assembly of active soft matter.

Pandey, Ankita; Adhikari, R

2014-01-01

279

Fluid flow in fault zones from an active rift  

NASA Astrophysics Data System (ADS)

The geometry and hydraulic properties of fault zones are investigated for Mesozoic greywacke basement and Miocene sandstone from ˜37 km of tunnels in the southern Taupo Rift, New Zealand. Localised groundwater inflows occur almost exclusively (?˜90%) within, and immediately adjacent to, fault zones. Fault zones in the contrasting lithologies comprise fault rock, small-scale faults, and fractures with thicknesses of 0.01-˜110 m approximating power law distributions and bulk permeabilities of 10-9-10-12 m2. Variability in fault zone structure results in a highly heterogeneous distribution of flow rates and locations. Within basement ˜80% of the flow rate occurs from fault zones ?10 m wide, with ˜30% of the total localised flow rate originating from a single fault zone (i.e. consistent with the golden fracture concept). No simple relationships are found between flow rates and either fault strike or hydraulic head, with ?50% of fault zones in any given orientation flowing. A general positive relationship does however exist between fault zone thickness and maximum flow rate. Higher flow rates from larger fault zones may arise because these structures have greater dimensions and are more likely (than smaller faults) to be connected to other faults in the system and the ground surface.

Seebeck, H.; Nicol, A.; Walsh, J. J.; Childs, C.; Beetham, R. D.; Pettinga, J.

2014-05-01

280

Laser Activated Flow Regulator for Glaucoma Drainage Devices  

PubMed Central

Purpose To assess the capabilities of a new glaucoma drainage device regulator in controlling fluid flow as well as to demonstrate that this effect may be titratable by noninvasive means. Methods A rigid eye model with two main ports was used. On the first port, we placed a saline solution column. On the second, we placed a glaucoma shunt. We then measured the flow and flow rate through the system. After placing the regulator device on the tip of the tube, we measured again with the intact membrane and with the membrane open 50% and 100%. For the ex vivo testing we used a similar setting, using a cadaveric porcine eye, we measured again the flow and flow rate. However, this time we opened the membrane gradually using laser shots. A one-way analysis of variance and a Fisher's Least Significant Difference test were used for statistical significance. We also calculated the correlation between the numbers of laser shots applied and the main outcomes. Results The flow through the system with the glaucoma drainage device regulator (membrane intact and 50% open) was statistically lower than with the membrane open 100% and without device (P < 0.05). The flow was successfully controlled by the number of laser shots applied, and showed a positive correlation (+ 0.9). The flow rate was almost doubled every 10 shots and statistically lower than without device at all time (P < 0.05). Conclusions The glaucoma drainage device regulator can be controlled noninvasively with laser, and allows titratable control of aqueous flow. Translational Relevance Initial results and evidence from this experiment will justify the initiation of in vivo animal trials with the glaucoma drainage device regulator; which brings us closer to possible human trials and the chance to significantly improve the existing technology to treat glaucoma surgically. PMID:25374772

Olson, Jeffrey L.; Velez-Montoya, Raul; Bhandari, Ramanath

2014-01-01

281

Multiple mechanisms in the thermally activated plastic flow of tantalum  

SciTech Connect

We argue that many of the features of the plastic flow behavior of tantalum can be described by a model that incorporates a two-component Peierls-type mechanism and an fcc-like obstacle mechanism in series. We compare the results of calculations based on such a model with flow data for unalloyed tantalum over a wide range of strain rates and a modest range of temperatures.

Gourdin, W.H.; Lassila, D.H.

1995-06-27

282

An active piezoelectric energy extraction method for pressure energy harvesting  

NASA Astrophysics Data System (ADS)

This paper presents an energy harvesting technique to power autonomous systems and more particularly active implantable medical devices. We employ a piezoelectric diaphragm placed in a fluidic environment such as blood subjected to very low frequency (2 Hz) pressure variations that is deflected in a quasi-static manner and transduces mechanical energy into electrical energy. In order to maximize energy generation and to get the most out of a given piezoelectric device, we propose to apply an optimized method to extract the piezoelectrically generated charge through the application of a controlled voltage. We believe that this method could be one of the improvement levers to achieve self-powered miniaturized implants. An analytical model is presented and shows that within its validity domain, the extracted energy is proportional to the desired applied voltage. Taking power electronics losses into account can yield a theoretical increase in the extracted energy of several thousand per cent. Experimental measurements in a pressure chamber have been carried out whose results corroborate the proposed model. For the tested setup, the application of a 10 V peak amplitude square-wave voltage increased the extracted energy by a factor of nine compared to a classical rectifier-based energy harvesting method.

Deterre, M.; Lefeuvre, E.; Dufour-Gergam, E.

2012-08-01

283

Energy Expenditure During Extravehicular Activity Through Apollo  

NASA Technical Reports Server (NTRS)

Monitoring crew health during manned space missions has always been an important factor to ensure that the astronauts can complete the missions successfully and within safe physiological limits. The necessity of real-time metabolic rate monitoring during extravehicular activities (EVAs) came into question during the Gemini missions, when the energy expenditure required to complete EVA tasks exceeded the life support capabilities for cooling and humidity control and, as a result, crew members ended the EVAs fatigued and overworked. This paper discusses the importance of real-time monitoring of metabolic rate during EVAs, and provides a historical look at energy expenditure during EVAs through the Apollo Program.

Paul, Heather L.

2012-01-01

284

Hypersonic flow around a sphere with CLL model of incomplete energy accommodation  

NASA Astrophysics Data System (ADS)

Hypersonic rarefied flow of nitrogen over a sphere is simulated by the Direct Simulation Monte Carlo (DSMC) calculations to study the drag coefficient under Lord's diffuse scattering modelwith incomplete energy accommodation. The flow field and drag results from free-molecule flow to transition regime flow are obtained for extreme cases of complete energy accommodation and zero accommodation (diffuse elastic reflection). Available wind tunnel experimental data agree with the complete energy accommodation limit. But incomplete energy accommodation may have remarkable influence on orbital drag of a satellite. The parameters needed for this incomplete energy accommodation model are usually determined by the analysis on the result of the experiment.

Liu, H. L.; Shen, C.

2001-08-01

285

Control of Vibratory Energy Harvesters in the Presence of Nonlinearities and Power-Flow Constraints  

NASA Astrophysics Data System (ADS)

Over the past decade, a significant amount of research activity has been devoted to developing electromechanical systems that can convert ambient mechanical vibrations into usable electric power. Such systems, referred to as vibratory energy harvesters, have a number of useful of applications, ranging in scale from self-powered wireless sensors for structural health monitoring in bridges and buildings to energy harvesting from ocean waves. One of the most challenging aspects of this technology concerns the efficient extraction and transmission of power from transducer to storage. Maximizing the rate of power extraction from vibratory energy harvesters is further complicated by the stochastic nature of the disturbance. The primary purpose of this dissertation is to develop feedback control algorithms which optimize the average power generated from stochastically-excited vibratory energy harvesters. This dissertation will illustrate the performance of various controllers using two vibratory energy harvesting systems: an electromagnetic transducer embedded within a flexible structure, and a piezoelectric bimorph cantilever beam. Compared with piezoelectric systems, large-scale electromagnetic systems have received much less attention in the literature despite their ability to generate power at the watt--kilowatt scale. Motivated by this observation, the first part of this dissertation focuses on developing an experimentally validated predictive model of an actively controlled electromagnetic transducer. Following this experimental analysis, linear-quadratic-Gaussian control theory is used to compute unconstrained state feedback controllers for two ideal vibratory energy harvesting systems. This theory is then augmented to account for competing objectives, nonlinearities in the harvester dynamics, and non-quadratic transmission loss models in the electronics. In many vibratory energy harvesting applications, employing a bi-directional power electronic drive to actively control the harvester is infeasible due to the high levels of parasitic power required to operate the drive. For the case where a single-directional drive is used, a constraint on the directionality of power-flow is imposed on the system, which necessitates the use of nonlinear feedback. As such, a sub-optimal controller for power-flow-constrained vibratory energy harvesters is presented, which is analytically guaranteed to outperform the optimal static admittance controller. Finally, the last section of this dissertation explores a numerical approach to compute optimal discretized control manifolds for systems with power-flow constraints. Unlike the sub-optimal nonlinear controller, the numerical controller satisfies the necessary conditions for optimality by solving the stochastic Hamilton-Jacobi equation.

Cassidy, Ian L.

286

Active Control by Conservation of Energy Concept  

NASA Technical Reports Server (NTRS)

Three unrelated experiments are discussed; each was extremely sensitive to initial conditions. The initial conditions are the beginnings of the origins of the information that nonlinearity displays. Initial conditions make the phenomenon unstable and unpredictable. With the knowledge of the initial conditions, active control requires far less power than that present in the system response. The first experiment is on the control of shocks from an axisymmetric supersonic jet; the second, control of a nonlinear panel response forced by turbulent boundary layer and sound; the third, control of subharmonic and harmonics of a panel forced by sound. In all three experiments, control is achieved by redistribution of periodic energy response such that the energy is nearly preserved from a previous uncontrolled state. This type of active control improves the performance of the system being controlled.

Maestrello, Lucio

2000-01-01

287

Brain activity during the flow experience: a functional near-infrared spectroscopy study.  

PubMed

Flow is the holistic experience felt when an individual acts with total involvement. Although flow is likely associated with many functions of the prefrontal cortex (PFC), such as attention, emotion, and reward processing, no study has directly investigated the activity of the PFC during flow. The objective of this study was to examine activity in the PFC during the flow state using functional near-infrared spectroscopy (fNIRS). Twenty right-handed university students performed a video game task under conditions designed to induce psychological states of flow and boredom. During each task and when completing the flow state scale for occupational tasks, change in oxygenated hemoglobin (oxy-Hb) concentration in frontal brain regions was measured using fNIRS. During the flow condition, oxy-Hb concentration was significantly increased in the right and left ventrolateral prefrontal cortex. Oxy-Hb concentration tended to decrease in the boredom condition. There was a significant increase in oxy-Hb concentration in the right and left dorsolateral prefrontal cortex, right and left frontal pole areas, and left ventrolateral PFC when participants were completing the flow state scale after performing the task in the flow condition. In conclusion, flow is associated with activity of the PFC, and may therefore be associated with functions such as cognition, emotion, maintenance of internal goals, and reward processing. PMID:24836375

Yoshida, Kazuki; Sawamura, Daisuke; Inagaki, Yuji; Ogawa, Keita; Ikoma, Katsunori; Sakai, Shinya

2014-06-24

288

An energy-aware active smart card  

Microsoft Academic Search

Abstract, Despite recent advances in smart card technology, most modern smart cards continue to rely on card readers for power and clock-ing, creating a potential security gap. In this paper we present an energy-aware smart card architecture that operates using an embedded battery and crystal. This low-power VLSI system is continually active and provides enhanced security through peri-odic internal update

Russell Tessier; David Jasinski; Atul Maheshwari; Aiyappan Natarajan; Weifeng Xu; Wayne P. Burleson

2005-01-01

289

Turbine Tip Clearance Active Flow Control using Plasma Actuators  

NASA Astrophysics Data System (ADS)

A low-speed linear cascade was used to examine the tip gap leakage flow and leakage vortex that exists within the low pressure turbine stage of a gas-turbine engine. The cascade array is composed of nine Pratt & Whitney ``PakB" blades, with the center blade having a variable tip gap up to five percent chord. Reynolds numbers based on axial chord varied from 10^4 to 10^5. Static pressure taps located at the midspan and near the tip of the blade were used to characterize the blade pressure distribution. A five-hole probe was also traversed in the downstream blade wake to ascertain velocity vectors and total pressure loss. Flow control in the form of a single-dielectric-barrier plasma actuator mounted on the blade tip was used to alter the leakage vortex by acting on the blade tip separation bubble, the blade tip shear layer instability, or the gap flow jet instability through the production of high frequency unsteady disturbances. The flow was documented through measurements with and without flow control for varying tip gaps and Reynolds numbers. The effect of the actuation on the tip leakage vortex and efficiency are investigated.

Vanness, Daniel

2005-11-01

290

High energy activation data library (HEAD-2009)  

SciTech Connect

A proton activation data library for 682 nuclides from 1 H to 210Po in the energy range from 150 MeV up to 1 GeV was developed. To calculate proton activation data, the MCNPX 2.6.0 and CASCADE/INPE codes were chosen. Different intranuclear cascade, preequilibrium, and equilibrium nuclear reaction models and their combinations were used. The optimum calculation models have been chosen on the basis of statistical correlations for calculated and experimental proton data taken from the EXFOR library of experimental nuclear data. All the data are written in ENDF-6 format. The library is called HEPAD-2008 (High-Energy Proton Activation Data). A revision of IEAF-2005 neutron activation data library has been performed. A set of nuclides for which the cross-section data can be (and were) updated using more modern and improved models is specified, and the corresponding calculations have been made in the present work. The new version of the library is called IEAF-2009. The HEPAD-2008 and IEAF-2009 are merged to the final HEAD-2009 library.

Mashnik, Stepan G [Los Alamos National Laboratory; Korovin, Yury A [NON LANL; Natalenko, Anatoly A [NON LANL; Konobeyev, Alexander Yu [NON LANL; Stankovskiy, A Yu [NON LANL

2010-01-01

291

A comparison of energy flow in micelle and vesicle structures.  

PubMed

We have investigated the vibrational population relaxation dynamics and state-dependent orientational relaxation behavior of perylene in micelles and vesicles formed using the same amphiphile(s). Decanoic acid and its conjugate base sodium decanoate can form either micelle or vesicle structures in aqueous solution depending on amphiphile concentration and solution pH. The issue of interest in this work is whether or not different assemblies of a given amphiphile manifest different efficiencies with the dissipation of energy. Vibrational population relaxation data show that initial energy flow from the chromophore to the amphiphile aliphatic chains is more efficient in micelles than in vesicles. Longer time scale relaxation, gauged by transient local heating induced by the dissipation of excess energy from perylene shows that the local environment formed by micelles experiences greater temperature change than the local environment formed by vesicles. This finding suggests that the strength of coupling between the bath and the amphiphiles differs for the two structural motifs. PMID:25601286

Pratama, Fredy; Blanchard, G J

2015-02-19

292

Active control of asymmetric vortical flows around cones using injection and heating  

NASA Technical Reports Server (NTRS)

The effectiveness of certain active-control methods for asymmetric flows around circular cones is investigated by using computational solution of the unsteady, compressible full Navier-Stokes equations. Two main methods of active control which include flow injection and surface heating are used. For the flow-injection-control method, flow injection is used either in the normal direction to the surface or in the tangential direction to the surface. For the surface-heating-control method, the temperature of the cone surface is increased. The effectiveness of a hybrid method of flow control which combines normal injection with surface heating has also been studied. The Navier-Stokes equations, subjected to various surface boundary conditions, are solved by using an implicit, upwind, flux-difference splitting, finite-volume scheme for locally-conical flow solutions.

Kandil, Osama A.; Sharaf, Hazem H.; Liu, C. H.

1992-01-01

293

Pigouvian taxation of energy for flow and stock externalities and strategic, noncompetitive energy pricing  

SciTech Connect

The literature on energy and carbon taxes is by and large concerned about the derivation of (globally) efficient strategies. In contrast, this paper considers the dynamic interactions between cartelized energy suppliers and a consumers' government that collectively taxes energy carriers for Pigouvian motives. Two different kinds of external costs are associated with energy consumption: flow (e.g., acid rain) and stock externalities (e.g., global warming). The dynamic interactions between a consumers' government and a producers' cartel are modeled as a differential game with a subgame perfect Nash equilibrium in linear and nonlinear Markov strategies. The major implications are that the nonlinear solutions are Pareto-inferior to the linear strategies and energy suppliers may preempt energy taxation and thereby may raise the price at front; however, this effect diminishes over time because the producers' price declines, while taxes increase. 22 refs., 5 figs., 1 tab.

Wirl, F. (Technical Univ. of Vienna (Austria))

1994-01-01

294

Debris flow activity related to recent climate conditions in the French Alps: A regional investigation  

NASA Astrophysics Data System (ADS)

The primary objective of this study was to document the relationships between current climatic conditions and debris flow activity in the French Alps based on a large historical database of debris flow events covering 35 years up to the present. The French Alps are composed of two contrasting geographic areas so two debris flow regions with different activity patterns were defined. For the period 1970-2005, the database contains 565 debris flow events in 87 catchments in the northern part of the French Alps, and in 150 catchments in the southern part. Possible links between debris flow and climate were investigated using two different approaches. The first approach was determining the rainfall thresholds responsible for triggering debris flow events by analysing the links between the intensity and the duration of rainfall events. The second approach used a probabilistic logit model to explore the links between the triggering of debris flow events and temperature and precipitation during the active debris flow period to identify inter-annual variability. Reanalysis data were used to document climate conditions in the two study areas. According to the results, in 80% of all debris flow events, precipitation was recorded during the three days preceding the event. However, in most cases, the quantity of precipitation associated with triggering of the debris flow was very low. Total precipitation exceeded 10 mm in only 30% of all cases. We attribute this to the convective nature of summer precipitation, which is quite difficult to model. Probabilistic analysis of the debris flow inventory in the two regions revealed that different parameters were responsible for changes in annual debris-flow activity. In the northern part of the French Alps, the number of rainy days and the maximum daily temperature affected debris flow, while in the southern part the only significant factor was mean daily temperature during the period of debris flow activity (May-October). Model scores had an accuracy of 75% and 70% in the northern and southern Alps, respectively. Our observations revealed that the increase in the above parameters has influenced changes in debris flow activity in both regions, where the number of debris flow events has doubled over the last 35 years.

Pavlova, Irina; Jomelli, Vincent; Brunstein, Daniel; Grancher, Delphine; Martin, Eric; Déqué, Michel

2014-08-01

295

Using Animated Textures to Visualize Electromagnetic Fields and Energy Flow  

E-print Network

Animated textures can be used to visualize the spatial structure and temporal evolution of vector fields at high spatial resolution. The animation requires two time-dependent vector fields. The first of these vector fields determines the spatial structure to be displayed. The second is a velocity field that determines the time evolution of the field lines of the first vector field. We illustrate this method with an example in magneto-quasi-statics, where the second velocity field is taken to be the ExB drift velocity of electric monopoles. This technique for displaying time-dependent electromagnetic fields has three pedagogical advantages: (1) the continuous nature of the representation underscores the action-by-contact nature of forces transmitted by fields; (2) the animated texture motion shows the direction of electromagnetic energy flow; and (3) the time-evolving field configuration enables insights into Maxwell stresses.

John Belcher; Carolann Koleci

2008-02-27

296

Electrochemical characterisation of activated carbon particles used in redox flow battery electrodes  

Microsoft Academic Search

The Faradaic and non-Faradaic characteristics of a series of activated carbon particles (used to produce composite carbon–polymer electrodes for redox flow cells) have been determined using aqueous electrolytes (sulfuric acid and sodium polysulfide) at 295K. The particles were mounted as a circular section (ca. 0.80cm2) shallow packed bed of 2.5mm thickness in the direction of electrolyte flow (mean linear flow

G. J. W. Radford; J. Cox; R. G. A. Wills; F. C. Walsh

2008-01-01

297

Experiments on active control of vibrational power flow using piezoceramic actuators and sensors  

NASA Technical Reports Server (NTRS)

The active control of flexural power flow in both semiinfinite and finite elastic beams is experimentally investigated. The experimental results demonstrate that piezoceramic transducers when used in conjunction with an adaptive least mean squares controller, can effectively control flexural power flow in thin beam systems. The piezoceramic transducers offer distinct size and weight advantages over conventional transducers. The experiments also demonstrate the use of an axial scanning laser vibrometer to determine out of plane velocity and power flow.

Gibbs, Gary P.; Fuller, Chris R.

1990-01-01

298

UML 2 activity model support for systems engineering functional flow diagrams  

Microsoft Academic Search

This article compares Activity models of the Unified Modeling Language, version 2 (UML 2) (OMG (Object Management Group), UML 2.0 superstructure specification, August 2003, http:\\/\\/www.omg.org\\/cgi-bin\\/doc?ptc\\/03-08-02), to a widely-used systems engineering (SE) flow diagram, the Enhanced Functional Flow Block Diagram (EFFBD) (J. Long, Relationships between common graphical representations in system engineering, ViTech Corporation, 2002), and to the requirements for functional flow

Conrad Bock

2003-01-01

299

A Variable Refrigerant Flow Heat Pump Computer Model in EnergyPlus  

SciTech Connect

This paper provides an overview of the variable refrigerant flow heat pump computer model included with the Department of Energy's EnergyPlusTM whole-building energy simulation software. The mathematical model for a variable refrigerant flow heat pump operating in cooling or heating mode, and a detailed model for the variable refrigerant flow direct-expansion (DX) cooling coil are described in detail.

Raustad, Richard A. [Florida Solar Energy Center

2013-01-01

300

Tail reconnection region versus auroral activity inferred from conjugate ARTEMIS plasma sheet flow and auroral observations  

NASA Astrophysics Data System (ADS)

sheet flow bursts have been suggested to correspond to different types of auroral activity, such as poleward boundary intensifications (PBIs), ensuing auroral streamers, and substorms. The flow-aurora association leads to the important question of identifying the magnetotail source region for the flow bursts and how this region depends on magnetic activity. The present study uses the ARTEMIS spacecraft coordinated with conjugate ground-based auroral imager observations to identify flow bursts beyond 45 RE downtail and corresponding auroral forms. We find that quiet-time flows are directed dominantly earthward with a one-to-one correspondence with PBIs. Flow bursts during the substorm recovery phase and during steady magnetospheric convection (SMC) periods are also directed earthward, and these flows are associated with a series of PBIs/streamers lasting for tens of minutes with similar durations to that of the series of earthward flows. Presubstorm onset flows are also earthward and associated with PBIs/streamers. The earthward flows during those magnetic conditions suggest that the flow bursts, which lead to PBIs and streamers, originate from further downtail of ARTEMIS, possibly from the distant-tail neutral line (DNL) or tailward-retreated near-Earth neutral line (NENL) rather than from the nominal NENL location in the midtail. We find that tailward flows are limited primarily to the substorm expansion phase. They continue throughout the period of auroral poleward expansion, indicating that the expansion-phase flows originate from the NENL and that NENL activity is closely related to the auroral expansion of the substorm expansion phase.

Nishimura, Y.; Lyons, L. R.; Xing, X.; Angelopoulos, V.; Donovan, E. F.; Mende, S. B.; Bonnell, J. W.; Auster, U.

2013-09-01

301

Evidence of active mantle flow beneath South China  

NASA Astrophysics Data System (ADS)

The India-Eurasia collision is responsible for producing the Himalayan Mountains and Tibetan plateau and has been hypothesized to have significant far field influences, including driving the Baikal rift and the eastward extrusion of South China. However, quantification of lithospheric buoyancy forces and integrated effect of tractions acting at base of the lithosphere are unable to explain the observed surface motions within South China. We present 198 new SKS shear wave splitting observations beneath South China and invert these data along with published GPS data to solve for the subasthenospheric flow field beneath South China to assess the role of small-scale convection here. We find a 15-20 mm/yr southwestward-directed mantle flow toward the Burma slab. This flow is consistent with the mantle response of slab retreat over the past 25 Ma, and counter flow due to subduction of Burma/Sunda slabs demonstrating the importance of localized mantle convection on present-day plate motions.

Wang, Chun-Yung; Flesch, Lucy M.; Chang, Lijun; Zheng, Tianyu

2013-10-01

302

Bitmap Algorithms for Counting Active Flows on High Speed Links  

E-print Network

are well understood, what are the corresponding functions that should be hardwired in the brave new world several Mbytes because the number of flows can be above a million. By contrast, our new probabilistic component of the popular intrusion detection sys- tem Snort with one of our new algorithms. This reduced

Zhou, Yuanyuan

303

Passive and Active Flow Control by Swimming Fishes and Mammals  

E-print Network

velocimetry, flukes, biomechanics, hydrodynamics, biomimetic Abstract What mechanisms of flow control do evolutionary history during which selection has acted on propulsive systems and generated an array of novel history and considerable new data that reflect growing interest in understanding how organisms control

Lauder, George V.

304

Flow cytometric analysis of crayfish haemocytes activated by lipopolysaccharides  

Microsoft Academic Search

Lipopolysaccharides (LPS) from Gram-negative bacteria are strong stimulators of white river crayfish, Procambarus zonangulus, haemocytes in vitro. Following haemocyte treatment with LPS and with LPS from rough mutant R5 (LPS Rc) from Salmonella minnesota, flow cytometric analysis revealed a conspicuous and reproducible decrease in cell size as compared to control haemocytes. These LPS molecules also caused a reduction in haemocyte

Washington Cárdenas; John R. Dankert; Jill A. Jenkins

2004-01-01

305

Blood flow in guinea fowl Numida meleagris as an indicator of energy expenditure by individual muscles during walking and running  

PubMed Central

Running and walking are mechanically complex activities. Leg muscles must exert forces to support weight and provide stability, do work to accelerate the limbs and body centre of mass, and absorb work to act as brakes. Current understanding of energy use during legged locomotion has been limited by the lack of measurements of energy use by individual muscles. Our study is based on the correlation between blood flow and aerobic energy expenditure in active skeletal muscle during locomotion. This correlation is strongly supported by the available evidence concerning control of blood flow to active muscle, and the relationship between blood flow and the rate of muscle oxygen consumption. We used injectable microspheres to measure the blood flow to the hind-limb muscles, and other body tissues, in guinea fowl (Numida meleagris) at rest, and across a range of walking and running speeds. Combined with data concerning the various mechanical functions of the leg muscles, this approach has enabled the first direct estimates of the energetic costs of some of these functions. Cardiac output increased from 350 ml min?1 at rest, to 1700 ml min?1 at a running speed (? 2.6 m s?1) eliciting a of 90% of . The increase in cardiac output was achieved via approximately equal factorial increases in heart rate and stroke volume. Approximately 90% of the increased cardiac output was directed to the active muscles of the hind limbs, without redistribution of blood flow from the viscera. Values of mass-specific blood flow to the ventricles, ? 15 ml min?1 g?1, and one of the hind-limb muscles, ? 9 ml min?1 g?1, were the highest yet recorded for blood flow to active muscle. The patterns of increasing blood flow with increasing speed varied greatly among different muscles. The increases in flow correlated with the likely fibre type distribution of the muscles. Muscles expected to have many high-oxidative fibres preferentially increased flow at low exercise intensities. We estimated substantial energetic costs associated with swinging the limbs, co-contraction to stabilize the knee and work production by the hind-limb muscles. Our data provide a basis for evaluating hypotheses relating the mechanics and energetics of legged locomotion. PMID:15731191

Ellerby, David J; Henry, Havalee T; Carr, Jennifer A; Buchanan, Cindy I; Marsh, Richard L

2005-01-01

306

Active procedures to control the flow past the Ahmed body with a 25  

E-print Network

Active procedures to control the flow past the Ahmed body with a 25 rear window Charles La Recherche, M´ecanique des fluides et a´erodynamique, DREAM/DTAA 1, Avenue du Golf F-78288 or slots are added on the body to control the flow. The results presented show that good drag reductions

Bruneau, Charles-Henri

307

Coupling active and passive techniques to control the flow past the square back Ahmed body  

E-print Network

Coupling active and passive techniques to control the flow past the square back Ahmed body Charles, Mécanique des fluides et aérodynamique DREAM/DTAA, Code API: TCR AVA 058 1, Avenue du Golf, F-78288 May 2010 Accepted 24 June 2010 Available online 3 July 2010 Keywords: Flow control Numerical

Bruneau, Charles-Henri

308

Hydrothermal fluid flow within a tectonically active rift-ridge transform junction: Tjörnes Fracture Zone, Iceland  

Microsoft Academic Search

We investigate the regional fluid flow dynamics in a highly faulted transform area, the Tjörnes Fracture Zone in northern Iceland which is characterized by steep geothermal gradients, hydrothermal activity, and strong seismicity. We simulate fluid flow within the Tjörnes Fracture Zone using a high-resolution model that was based on the available geological and geophysical data and has the aim to

M. Lupi; S. Geiger; C. M. Graham

2010-01-01

309

More-Than-Topology-Preserving Flows for Active Contours and Polygons Ganesh Sundaramoorthi and Anthony Yezzi  

E-print Network

More-Than-Topology-Preserving Flows for Active Contours and Polygons Ganesh Sundaramoorthi widely for image segmentation. In some applications, the topology of the object(s) to be detected from contour or polygon maintain the desired topology. In this work, we construct a novel ge- ometric flow

Soatto, Stefano

310

An Active Region Model for Capturing Fractal Flow Patterns inUnsaturated Soils: Model Development  

SciTech Connect

Preferential flow commonly observed in unsaturated soils allows rapid movement of solute from the soil surface or vadose zone to the groundwater, bypassing a significant volume of unsaturated soil and increasing the risk of groundwater contamination. A variety of evidence indicates that complex preferential patterns observed from fields are fractals. In this study, we developed a relatively simple active region model to incorporate the fractal flow pattern into the continuum approach. In the model, the flow domain is divided into active and inactive regions. Flow occurs preferentially in the active region (characterized by fractals), and inactive region is simply bypassed. A new constitutive relationship (the portion of the active region as a function of saturation) was derived. The validity of the proposed model is demonstrated by the consistency between field observations and the new constitutive relationship.

Liu, Hui-Hai; Zhang, R.; Bodvarsson, Gudmundur S.

2005-06-11

311

Blood flow controls coagulation onset via the positive feedback of factor VII activation by factor Xa  

PubMed Central

Background Blood coagulation is a complex network of biochemical reactions, which is peculiar in that it is time- and space-dependent, and has to function in the presence of rapid flow. Recent experimental reports suggest that flow plays a significant role in its regulation. The objective of this study was to use systems biology techniques to investigate this regulation and to identify mechanisms creating a flow-dependent switch in the coagulation onset. Results Using a detailed mechanism-driven model of tissue factor (TF)-initiated thrombus formation in a two-dimensional channel we demonstrate that blood flow can regulate clotting onset in the model in a threshold-like manner, in agreement with existing experimental evidence. Sensitivity analysis reveals that this is achieved due to a combination of the positive feedback of TF-bound factor VII activation by activated factor X (Xa) and effective removal of factor Xa by flow from the activating patch depriving the feedback of "ignition". The level of this trigger (i.e. coagulation sensitivity to flow) is controlled by the activity of tissue factor pathway inhibitor. Conclusions This mechanism explains the difference between red and white thrombi observed in vivo at different shear rates. It can be speculated that this is a special switch protecting vascular system from uncontrolled formation and spreading of active coagulation factors in vessels with rapidly flowing blood. PMID:20102623

2010-01-01

312

Experimental and computational studies of active flow control on a model truck-trailer  

NASA Astrophysics Data System (ADS)

Active flow control is probably the most challenging research area in vehicle aerodynamics. Being able to manipulate a flow field in order to achieve desired results beneficial to engineering is the only way to meet today's demands for competitive and efficient solutions in the automotive industry. The current work studies the flow control on a semi detailed model truck by using detached-eddy simulations and wind tunnel experiments aiming at reducing the aerodynamic drag. This study combines both passive and active flow control applied on the rear end of the trailer. An indigenous fluidic actuator (loudspeaker in cavity with slots) is used as a synthetic jet in the experiment. Both experiments and computations demonstrate that the active flow control works successfully and results in flow reattachment to the flaps. The numerical simulations show that the drag coefficient, CD decreased by 3.9% when AFC was activated compared to the baseline case without flaps. The corresponding decrease when AFC was deactivated (with flaps) was only 0.7%. The experimental results show a decrease of CD by 3.1% for the case with activated AFC compared to the baseline case. When AFC was deactivated the corresponding decrease in CD was 1.8%. A detailed flow analysis made in computations and experiments is used to explain these results.

El-Alti, Mohammad; Chernoray, Valery; Jahanmiri, Mohsen; Davidson, Lars

2012-04-01

313

Polytropic dark matter flows illuminate dark energy and accelerated expansion  

NASA Astrophysics Data System (ADS)

Currently, a large amount of data implies that the matter constituents of the cosmological dark sector might be collisional. An attractive feature of such a possibility is that, it can reconcile dark matter (DM) and dark energy (DE) in terms of a single component, accommodated in the context of a polytropic-DM fluid. In fact, polytropic processes in a DM fluid have been most successfully used in modeling dark galactic haloes, thus significantly improving the velocity dispersion profiles of galaxies. Motivated by such results, we explore the time evolution and the dynamical characteristics of a spatially-flat cosmological model, in which, in principle, there is no DE at all. Instead, in this model, the DM itself possesses some sort of fluidlike properties, i.e., the fundamental units of the Universe matter-energy content are the volume elements of a DM fluid, performing polytropic flows. In this case, together with all the other physical characteristics, we also take the energy of this fluid's internal motions into account as a source of the universal gravitational field. This form of energy can compensate for the extra energy, needed to compromise spatial flatness, namely, to justify that, today, the total energy density parameter is exactly unity. The polytropic cosmological model, depends on only one free parameter, the corresponding (polytropic) exponent, ?. We find this model particularly interesting, because for ? ? 0.541, without the need for either any exotic DE or the cosmological constant, the conventional pressure becomes negative enough so that the Universe accelerates its expansion at cosmological redshifts below a transition value. In fact, several physical reasons, e.g., the cosmological requirement for cold DM (CDM) and a positive velocity-of-sound square, impose further constraints on the value of ?, which is eventually settled down to the range -0.089 < ? ? 0. This cosmological model does not suffer either from the age problem or from the coincidence problem. At the same time, this model reproduces to high accuracy the distance measurements performed with the aid of the supernovae (SNe) Type Ia standard candles, and most naturally interprets, not only when, but also why the Universe transits from deceleration to acceleration, thus arising as a mighty contestant for a DE model.

Kleidis, K.; Spyrou, N. K.

2015-04-01

314

Evidence of active mantle flow beneath South China (Invited)  

NASA Astrophysics Data System (ADS)

The India-Eurasia collision is responsible for producing the Himalayan Mountains and Tibetan plateau and has been hypothesized to have significant far field influences, including driving the Baikal rift and the eastward extrusion of South China. Quantification of lithospheric buoyancy forces and integrated effect of tractions acting at base of the lithosphere are unable to explain the observed deformation around the Eastern Himalayan Syntaxis and within South China. We present 198 new SKS shear-wave splitting observations beneath South China and invert these data along with published GPS data to map a 15-20 mm/yr southwestward-directed mantle flow towards the Burma slab that is consistent with the mantle response of slab retreat over the past 25ma, a slab hole between the Burma and Sunda subductions zones, and counter flow due to subduction of Burma/Sunda slabs demonstrating the importance of localized mantle convection and past plate geometries on present day plate motions.

Flesch, L. M.; Wang, C.; Chang, L.; Zheng, T.

2013-12-01

315

The subendothelial extracellular matrix modulates NF-?B activation by flow  

PubMed Central

Atherosclerotic plaque forms in regions of the vasculature exposed to disturbed flow. NF-?B activation by fluid flow, leading to expression of target genes such as E-selectin, ICAM-1, and VCAM-1, may regulate early monocyte recruitment and fatty streak formation. Flow-induced NF-?B activation is downstream of conformational activation of integrins, resulting in new integrin binding to the subendothelial extracellular matrix and signaling. Therefore, we examined the involvement of the extracellular matrix in this process. Whereas endothelial cells plated on fibronectin or fibrinogen activate NF-?B in response to flow, cells on collagen or laminin do not. In vivo, fibronectin and fibrinogen are deposited at atherosclerosis-prone sites before other signs of atherosclerosis. Ligation of integrin ?2?1 on collagen prevents flow-induced NF-?B activation through a p38-dependent pathway that is activated locally at adhesion sites. Furthermore, altering the extracellular matrix to promote p38 activation in cells on fibronectin suppresses NF-?B activation, suggesting a novel therapeutic strategy for treating atherosclerosis. PMID:15809308

Orr, A. Wayne; Sanders, John M.; Bevard, Melissa; Coleman, Elizabeth; Sarembock, Ian J.; Schwartz, Martin Alexander

2005-01-01

316

Large Trucks Drag Reduction using Active Flow Control  

Microsoft Academic Search

Aerodynamic drag is the cause for more than two-thirds of the fuel consumption of large trucks at highway speeds. Due to functionality\\u000a considerations, the aerodynamic efficiency of the aft-regions of large trucks was traditionally sacrificed. This leads to\\u000a massively separated flow at the lee-side of truck-trailers, with an associated drag penalty of at least a third of the total\\u000a aerodynamic

A. Seifert; O. Stalnov; D. Sperber; G. Arwatz; V. Palei; S. David; I. Dayan; I. Fono

317

Numerical studies of the application of active flow control to subsonic and transonic airfoil flows using a synthetic jet actuator  

NASA Astrophysics Data System (ADS)

Active control of flow over airfoils is currently an area of heightened interest in the aerospace community because of its potential in reducing drag, eliminating separation at high angles of attack, and modulating the aerodynamic forces and moments. We study these possibilities by performing several numerical simulations. Numerical simulations are performed by employing an Unsteady Reynolds-Averaged Navier-Stokes (URANS) equations solver in conjunction with a two-equation Shear-Stress-Transport (SST) turbulence model. In particular, the computations are performed for the following three classes of flows: (1) Subsonic flow past a 24% thick Clark-Y airfoil with a triangular bump on the upper surface with and without a synthetic jet actuator. The goal is to perform numerical simulations of this experimentally observed fluidic modification of airfoil pressure distributions leading to reduced pressure drag. The computations are compared with experiments performed at Georgia Tech. (2) Transonic flow past a NACA64A010 airfoil with a synthetic jet actuator. The goal is to control the shock/boundary layer interaction on the airfoil using a synthetic jet actuator to reduce drag as well to achieve desired modulation of aerodynamic forces and moments. (3) Subsonic flow past a commercial supercritical airfoil leveraging the presence of a Gurney flap with a synthetic jet actuator. The goal is again to improve the aerodynamic performance (increase or maintain lift and reduce drag) by using a synthetic jet actuator integrated in a bump on the pressure surface of the airfoil near the trailing edge. The computations are compared with the experiments performed at Georgia Tech. The computations as well as the experiments show the feasibility of active flow control in reducing the drag of airfoils and in achieving the desired modulation of aerodynamic forces and moments.

Vadillo, Jose L.

2005-07-01

318

Activation energy of water desorption from guanosine.  

NASA Astrophysics Data System (ADS)

The interactions of the nucleic acids with their water of hydration are of fundamental importance and still imperfectly understood. As an initial effort, we have studied a component of RNA: the nucleoside guanosine (rG), composed of the ribose sugar and the guanine base. The interactions of the water of primary hydration with rG have been studied via thermogravimetric measurements and differential thermal analysis. These data yield the activation energy for the desorption of the water of primary hydration from rG.

Smith, Megan; Lee, Scott

2008-10-01

319

MAGNETIC ENERGY SPECTRA IN SOLAR ACTIVE REGIONS  

SciTech Connect

Line-of-sight magnetograms for 217 active regions (ARs) with different flare rates observed at the solar disk center from 1997 January until 2006 December are utilized to study the turbulence regime and its relationship to flare productivity. Data from the SOHO/MDI instrument recorded in the high-resolution mode and data from the BBSO magnetograph were used. The turbulence regime was probed via magnetic energy spectra and magnetic dissipation spectra. We found steeper energy spectra for ARs with higher flare productivity. We also report that both the power index, {alpha}, of the energy spectrum, E(k) {approx} k{sup -}{alpha}, and the total spectral energy, W = {integral}E(k)dk, are comparably correlated with the flare index, A, of an AR. The correlations are found to be stronger than those found between the flare index and the total unsigned flux. The flare index for an AR can be estimated based on measurements of {alpha} and W as A = 10{sup b}({alpha}W){sup c}, with b = -7.92 {+-} 0.58 and c = 1.85 {+-} 0.13. We found that the regime of the fully developed turbulence occurs in decaying ARs and in emerging ARs (at the very early stage of emergence). Well-developed ARs display underdeveloped turbulence with strong magnetic dissipation at all scales.

Abramenko, Valentyna; Yurchyshyn, Vasyl [Big Bear Solar Observatory, 40386 N. Shore Lane, Big Bear City, CA 92314 (United States)

2010-09-01

320

Efficient Ionization Investigation for Flow Control and Energy Extraction  

NASA Technical Reports Server (NTRS)

Nonequilibrium ionization of air by nonthermal means is explored for hypersonic vehicle applications. The method selected for evaluation generates a weakly ionized plasma using pulsed nanosecond, high-voltage discharges sustained by a lower dc voltage. These discharges promise to provide a means of energizing and sustaining electrons in the air while maintaining a nearly constant ion/neutral molecule temperature. This paper explores the use of short approx.5 nsec, high-voltage approx.12 to 22 kV, repetitive (40 to 100 kHz) discharges in generating a weakly ionized gas sustained by a 1 kV dc voltage in dry air at pressures from 10 to 80 torr. Demonstrated lifetimes of the sustainer discharge current approx.10 to 25 msec are over three orders of magnitude longer than the 5 nsec pulse that generates the electrons. This life is adequate for many high speed flows, enabling the possibility of exploiting weakly ionized plasma phenomena in flow-fields such as those in hypersonic inlets, combustors, and nozzles. Results to date are obtained in a volume of plasma between electrodes in a bell jar. The buildup and decay of the visible emission from the pulser excited air is photographed on an ICCD camera with nanosecond resolution and the time constants for visible emission decay are observed to be between 10 to 15 nsec decreasing as pressure increases. The application of the sustainer voltage does not change the visible emission decay time constant. Energy consumption as indicated by power output from the power supplies is 194 to 669 W depending on pulse repetition rate.

Schneider, Steven J.; Kamhawi, Hani; Blankson, Isaiah M.

2009-01-01

321

Broadening of activity with flow across neural structures  

PubMed Central

Synfire chains have long been suggested as a substrate for perception and information processing in the nervous system. However, embedding activation chains in a densely connected nervous matrix risks spread of signal that will obscure or obliterate the message. We used computer modeling and physiological measurements in rat hippocampus to assess this problem of activity broadening. We simulated a series of neural modules with feedforward propagation and random connectivity within each module and from one module to the next. We found that activity broadened as it propagated from one module to the next. This occurred over a wide array of parameters with greater broadening seen due to increasing excitatory-excitatory synaptic strength. Activity broadening correlated positively with propagation velocity. Multi-electrode measurements of activity propagation in disinhibited CA1 slice demonstrated broadening of about 50% over 1 mm. Such broadening is a problem for information transfer that must be dealt with in a fully functioning nervous system. PMID:18491717

Lytton, William; Orman, Rena; Stewart, Mark

2009-01-01

322

How Large Scale Flows in the Solar Convection Zone may Influence Solar Activity  

NASA Technical Reports Server (NTRS)

Large scale flows within the solar convection zone are the primary drivers of the Sun s magnetic activity cycle. Differential rotation can amplify the magnetic field and convert poloidal fields into toroidal fields. Poleward meridional flow near the surface can carry magnetic flux that reverses the magnetic poles and can convert toroidal fields into poloidal fields. The deeper, equatorward meridional flow can carry magnetic flux toward the equator where it can reconnect with oppositely directed fields in the other hemisphere. These axisymmetric flows are themselves driven by large scale convective motions. The effects of the Sun s rotation on convection produce velocity correlations that can maintain the differential rotation and meridional circulation. These convective motions can influence solar activity themselves by shaping the large-scale magnetic field pattern. While considerable theoretical advances have been made toward understanding these large scale flows, outstanding problems in matching theory to observations still remain.

Hathaway, D. H.

2004-01-01

323

Numerical Modeling of Active Flow Control in a Boundary Layer Ingesting Offset Inlet  

NASA Technical Reports Server (NTRS)

This investigation evaluates the numerical prediction of flow distortion and pressure recovery for a boundary layer ingesting offset inlet with active flow control devices. The numerical simulations are computed using a Reynolds averaged Navier-Stokes code developed at NASA. The numerical results are validated by comparison to experimental wind tunnel tests conducted at NASA Langley Research Center at both low and high Mach numbers. Baseline comparisons showed good agreement between numerical and experimental results. Numerical simulations for the inlet with passive and active flow control also showed good agreement at low Mach numbers where experimental data has already been acquired. Numerical simulations of the inlet at high Mach numbers with flow control jets showed an improvement of the flow distortion. Studies on the location of the jet actuators, for the high Mach number case, were conducted to provide guidance for the design of a future experimental wind tunnel test.

Allan, Brian G.; Owens, Lewis R.; Berrier, Bobby L.

2004-01-01

324

Technologies for energy storage-Present and future: flow batteries  

Microsoft Academic Search

Flow batteries, sometimes known as redox batteries, flow cells or regenerative fuel cells are a special kind of electrochemical device, lying between a secondary battery and a fuel cell. In common with a secondary battery they can be charged and discharged. Fuel cells can deliver power for as long as they are supplied with fuel and an oxidising agent. Flow

A. Price

2000-01-01

325

Measurements of energy distribution and wall temperature in flowing hydrogen microwave plasma systems  

NASA Technical Reports Server (NTRS)

An electrothermal propulsion concept utilizing a microwave plasma system as the mechanism to convert electromagnetic energy into translational energy of the flowing gas is being investigated. A calorimetric experimental system has been designed and built enclosing the microwave plasma system to accurately determine the net energy transferred to the flowing gas. For a flow rate of 8900 micromoles/sec, a pressure of 7.4 torr, and an absorbed power level of 80 W, an energy transfer efficiency of 50 percent has been measured. A heat transfer model that characterizes the energy transfer processes in the plasma is developed. A wall temperature for the plasma system is calculated.

Chapman, R.; Finzel, M.; Hawley, M. C.

1985-01-01

326

Energy and momentum flow in electromagnetic fields and plasma. [solar wind-magnetospheric interaction  

NASA Technical Reports Server (NTRS)

The energy momentum tensor for a perfect fluid in a magnetic field is used to predict the momentum density, energy density, momentum flow, and energy flow of the fluid and the electromagnetic field. It is shown that taking the momentum flow from the energy momentum tensor, rather than starting with differential magnetohydrodynamic equations, can produce more accurate results on the basis of magnetic field data. It is suggested that the use of the energy momentum tensor has the potential for application to analysis of data from the more dynamic regions of the solar system, such as the plasma boundaries of Venus, the Jovian ionosphere, and the terrestrial magnetopause.

Parish, J. L.; Raitt, W. J.

1983-01-01

327

Mathematics. Iowa Developed Energy Activity Sampler, 6-12. Revised.  

ERIC Educational Resources Information Center

The revised Iowa Developed Energy Activity Sampler (IDEAS) was compiled using the original IDEAS program and the Energy Conservation Activity Packets (ECAPS). This document contains teaching activities which are intended to strengthen students' mathematics skills and concepts, while broadening their understanding of energy concepts. Each of the 24…

Iowa State Dept. of Education, Des Moines. Div. of Instructional Services.

328

Analytical Model of Water Flow in Coal with Active Matrix  

NASA Astrophysics Data System (ADS)

This paper presents new analytical model of gas-water flow in coal seams in one dimension with emphasis on interactions between water flowing in cleats and coal matrix. Coal as a flowing system, can be viewed as a solid organic material consisting of two flow subsystems: a microporous matrix and a system of interconnected macropores and fractures. Most of gas is accumulated in the microporous matrix, where the primary flow mechanism is diffusion. Fractures and cleats existing in coal play an important role as a transportation system for macro scale flow of water and gas governed by Darcy's law. The coal matrix can imbibe water under capillary forces leading to exchange of mass between fractures and coal matrix. In this paper new partial differential equation for water saturation in fractures has been formulated, respecting mass exchange between coal matrix and fractures. Exact analytical solution has been obtained using the method of characteristics. The final solution has very simple form that may be useful for practical engineering calculations. It was observed that the rate of exchange of mass between the fractures and the coal matrix is governed by an expression which is analogous to the Newton cooling law known from theory of heat exchange, but in present case the mass transfer coefficient depends not only on coal and fluid properties but also on time and position. The constant term of mass transfer coefficient depends on relation between micro porosity and macro porosity of coal, capillary forces, and microporous structure of coal matrix. This term can be expressed theoretically or obtained experimentally. W artykule zaprezentowano nowy model matematyczny przep?ywu wody i gazu w jednowymiarowej warstwie w?glowej z uwzgl?dnieniem wymiany masy mi?dzy systemem szczelin i matryc? w?glow?. W?giel jako system przep?ywowy traktowany jest jako uk?ad o podwójnej porowato?ci i przepuszczalno?ci, sk?adaj?cy si? z mikroporowatej matrycy w?glowej oraz z systemu szczelin, sp?ka? i ewentualnie najwi?kszych porów. Przep?ywowi w systemie szczelin towarzyszy? mo?e wymiana masy z matryc?, której intensywno?? zale?y m.in. od w?a?ciwo?ci w?gla i warunków panuj?cych w uk?adzie przep?ywowym. W szczególno?ci matryca w?glowa mo?e poch?ania? wod? pod wp?ywem si? kapilarnych, co wp?ywa na przep?yw w szczelinach. W artykule zosta?o zaproponowane równanie ró?niczkowe cz?stkowe opisuj?ce nasycenie wod? w systemie szczelin z uwzgl?dnieniem wymiany masy z matryc? pod wp?ywem si? kapilarnych. Podano dok?adne rozwi?zanie analityczne, które mo?e by? zastosowane w praktyce in?ynierskiej. Zauwa?ono, ?e szybko?? wymiany masy mi?dzy szczelinami i matryc? wyra?a si? formu?? analogiczn? do prawa stygni?cia Newtona, ale w analizowanym przypadku wspó?czynnik wymiany masy zale?y nie tylko od w?a?ciwo?ci w?gla i p?ynów ale równie? od po?o?enia i czasu. Sta?y cz?on tego wspó?czynnika mo?e by? obliczony teoretycznie lub wyznaczony eksperymentalnie

Siemek, Jakub; Stopa, Jerzy

2014-12-01

329

Characterizing soil preferential flow using iodine--starch staining experiments and the active region model  

SciTech Connect

Thirteen iodine-starch staining experiments with different boundary conditions and measurement scales were conducted at two sites to study preferential flow processes in natural unsaturated soils. Digital imaging analyses were implemented to obtain the corresponding preferential flow patterns. The test results are used to evaluate a recently proposed active region model in terms of its usefulness and robustness for characterizing unsaturated flow processes at field scale. Test results provide useful insights into flow patterns in unsaturated soils. They show that flow pattern depends on the top boundary condition. As the total infiltrating-water depth increased form 20 mm to 80 mm for the 100 x 100 cm{sup 2} plots, the corresponding flow pattern changed from few preferential flow paths associated with a relatively small degree of stained coverage and a small infiltration depth, to a pattern characterized by a higher stained coverage and a larger infiltration depth, and to (finally) a relatively homogeneous flow pattern with few unstained area and a much larger infiltration depth. Test results also show that the preferential flow pattern became generally more heterogeneous and complex for a larger measurement scale (or size of infiltration plot). These observations support the general idea behind the active region model that preferential flow pattern in unsaturated soils are dynamic and depend on water flow conditions. Further analyses of the test results indicate that the active-region model is able to capture the major features of the observed flow pattern at the scale of interest, and the determined parameter values do not significantly depend on the test conditions (initial water content and total amount of infiltrating water) for a given test site. This supports the validity of the active region model that considers that parameter to be a property of the corresponding unsaturated soil. Results also show that some intrinsic relation seems to exist between active-fracture-model parameter and a random-cascade-model parameter. (The latter model is also developed based on the existence of the fractal flow pattern in unsaturated soils.) Furthermore, our test results demonstrate that the active-region-model parameter is not scale-dependent for a range of scales under consideration. Although further studies are needed to confirm this finding, it seems to be consistent with a consideration that some fractal parameters (e.g., fractal dimension) are universal for a large range of scales.

Sheng, Feng; Wang, Kang; Zhang, Renduo; Liu, Hui-Hai

2009-03-01

330

Numerical model for the flow within the tower of a tornado-type wind energy system  

SciTech Connect

A two-equation turbulence model is used to predict numerically the flow within the tower of a tornado-type wind energy system. Calculations are carried out for a tower in a uniform flow. Both cases of closed-bottom tower and simulated turbine flow with a variety of turbine-to-tower diameter ratios and turbine flow rates are considered. Calculated values of pressure for closed-bottom tower are compared with experimental values. 11 refs.

Ayad, S.S.

1981-11-01

331

Dielectric barrier plasma dynamics for active control of separated flows  

SciTech Connect

The dynamics of separation mitigation with asymmetric dielectric barrier discharges is explored by considering the gas flow past a flat plate at an angle of attack. A self-consistent model utilizing motion of electrons, ions, and neutrals is employed to couple the electric force field to the momentum of the fluid. The charge separation and concomitant electric field yield a time-averaged body force which is oriented predominantly downstream, with a smaller transverse component towards the wall. This induces a wall-jet-like feature that effectively eliminates the separation bubble. The impact of several geometric and electrical operating parameters is elucidated.

Roy, Subrata; Singh, K.P.; Gaitonde, Datta V. [Computational Plasma Dynamics Laboratory, Mechanical Engineering, Kettering University, Flint, Michigan 48504 (United States); Computational Sciences Branch, Air Vehicles Directorate, Air Force Research Laboratory, Wright Patterson AFB, Ohio 45433 (United States)

2006-03-20

332

Ambiguous hydraulic heads and 14C activities in transient regional flow.  

PubMed

A regional flow and transport model is used to explore the implications of significant variability in Pleistocene and Holocene climates on hydraulic heads and (14)C activity. Simulations involve a 39 km slice of the Death Valley Flow System through Yucca Mountain toward the Amargosa Desert. The long-time scale over which infiltration has changed (tens-of-thousands of years) is matched by the large physical extent of the flow system (many tens-of-kilometers). Estimated paleo-infiltration rates were estimated using a juniper pollen percentage that extends from the last interglacial (LIG) period (approximately 120 kyrbp) to present. Flow and (14)C transport simulations show that groundwater flow changes markedly as a function of paleoclimate. At the last glacial maximum (LGM, 21 kyrbp), the recharge to the flow system was about an order-of-magnitude higher than present, and water table was more than 100 m higher. With large basin time constants, flow is complicated because hydraulic heads at a given location reflect conditions of the past, but at another location the flow may reflect present conditions. This complexity is also manifested by processes that depend on flow, for example (14)C transport. Without a model that accounts for the historical transients in recharge for at least the last 20,000 years, there is no simple way to deconvolve the (14)C dates to explain patterns of flow. PMID:20015221

Schwartz, Franklin W; Sudicky, Edward A; McLaren, Robert G; Park, Young-Jin; Huber, Matthew; Apted, Mick

2010-01-01

333

Distribution of Bacterial Growth Activity in Flow-Chamber Biofilms  

Microsoft Academic Search

In microbial communities such as those found in biofilms, individual organisms most often display heter- ogeneous behavior with respect to their metabolic activity, growth status, gene expression pattern, etc. In that context, a novel reporter system for monitoring of cellular growth activity has been designed. It comprises a transposon cassette carrying fusions between the growth rate-regulated Escherichia coli rrnBP1 promoter

CLAUS STERNBERG; BJARKE B. CHRISTENSEN; TOVE JOHANSEN; ALEX TOFTGAARD NIELSEN; JENS BO ANDERSEN; MICHAEL GIVSKOV; SØREN MOLIN

1999-01-01

334

An Energy-Flow Model for Self-Powered Routers and its Application for Energy-Aware Routing  

E-print Network

An Energy-Flow Model for Self-Powered Routers and its Application for Energy-Aware Routing Veljko@inf.ed.ac.uk ABSTRACT Self-powered wireless mesh networks have gained popularity as a cheap alternative for providing of electrical energy. Depen- dence on renewable energy sources and variable power consump- tion make

Belding-Royer, Elizabeth M.

335

Activities contributing to energy expenditure among Guatemalan adults  

Microsoft Academic Search

BACKGROUND: Guatemala has experienced a substantial increase in overweight and obesity in recent years, yet physical activity patterns and consequent energy expenditure are largely unexplored in this population. METHODS: To describe overall physical activity levels (PAL) and activities contributing to daily energy expenditure, we analyzed time spent in daily activities as reported by 985 women and 819 men, living in

Cria O Gregory; Manuel Ramirez-Zea; Reynaldo Martorell; Aryeh D Stein

2007-01-01

336

Factors Affecting the Performance of Open Borehole Thermal Energy Storage System under Continuous Flow Regime  

Microsoft Academic Search

This article presents coupled hydrogeological-thermal simulation of open borehole thermal energy storage system operating under continuous flow regime. A three-dimensional numerical model for groundwater flow and heat transport is used to analyze the thermal energy storage in the ground. The operation scenario consists of continuous injection and recovery and four periods per year to simulate the seasonal temperature conditions. For

K. S. Lee

2009-01-01

337

Energy flow and elemental concentrations in the Steina River ecosystem (Black Forest, Germany)  

Microsoft Academic Search

Considering food web energetics and elemental cycling together allows the testing of hypotheses about the coevolution of biological systems and their physical environment. We investigated the energy flow and the distribution of 25 elements in the Steina River.¶We constructed an annual energy flow network and estimated the emergy (\\

Giulio P. Genoni; Elisabeth I. Meyer; Andrea Ulrich

2003-01-01

338

Title: Scalable Low-Head Axial-Type Venturi-Flow Energy Principal Investigator: Nadipuram Prasad  

E-print Network

Title: Scalable Low-Head Axial-Type Venturi-Flow Energy Scavenger (SLAVES) Principal Investigator: Nadipuram Prasad Sponsor: U.S. Department of Energy Summary: In-depth studies of the turbine dynamics for an axial-flow hydropower generating system will show the technical feasibility to harvest or scavenge

Johnson, Eric E.

339

The Limit of Free Magnetic Energy in Active Regions  

NASA Technical Reports Server (NTRS)

By measuring from active-region magnetograms a proxy of the free energy in the active region fs magnetic field, it has been found previously that (1) there is an abrupt upper limit to the free energy the field can hold that increases with the amount of magnetic field in the active region, the active region fs magnetic flux content, and (2) the free energy is usually near its limit when the field explodes in a CME/flare eruption. That is, explosive active regions are concentrated in a main-sequence path bordering the free-energy ]limit line in (flux content, free-energy proxy) phase space. Here, from measurement of Marshall Space Flight Center vector magnetograms, we find the magnetic condition that underlies the free ]energy limit and the accompanying main sequence of explosive active regions. Using a suitable free ]energy proxy measured from vector magnetograms of 44 active regions, we find that (1) in active regions at and near their free ]energy limit, the ratio of magnetic-shear free energy to the non ]free magnetic energy the potential field would have is approximately 1 in the core field, the field rooted along the neutral line, and (2) this ratio is progressively less in active regions progressively farther below their free ]energy limit. This shows that most active regions in which this core-field energy ratio is much less than 1 cannot be triggered to explode; as this ratio approaches 1, most active regions become capable of exploding; and when this ratio is 1 or greater, most active regions are compelled to explode. From these results we surmise the magnetic condition that determines the free ]energy limit is the ratio of the free magnetic energy to the non-free energy the active region fs field would have were it completely relaxed to its potential ]field configuration, and that this ratio is approximately 1 at the free-energy limit and in the main sequence of explosive active regions.

Moore, Ron; Falconer, David; Sterling, Alphonse

2012-01-01

340

Vortex-enhanced mixing through active and passive flow control methods  

NASA Astrophysics Data System (ADS)

This study aims to understand the underlying physics of vortex-enhanced mixing through active and passive flow control methods. To find a best flow control method that enhances turbulent mixing through the generation of streamwise vortices, an experimental investigation was carried out to compare active and passive flow control methods of an incompressible axisymmetric jet. For active flow control, the lip of the circular jet was equipped with a single small flap deflected away from the jet stream at an angle of 30° to the jet axis. The flap incorporated a flow control slot through which steady and oscillatory suction were implemented. The active flow control methods require power input to the suction devices. For passive flow control, the lip of the circular jet was equipped with a single small delta tab deflected into the jet stream at an angle of 30° to the jet axis. The chord lengths of the flap and delta tab were one-sixth of the jet diameter. The momentum of jet increased in the case of active flow control by entraining the ambient fluid, whereas momentum decreased in the case of passive flow control. The effect of steady suction saturated for volumetric suction coefficient values greater than 0.82 %. The strength of streamwise vortices generated by the flap were greater than those generated by the delta tab. Steady suction produced positive pressures just downstream of the flow control slot in the central portion of the flap and negative pressures at the flap edges. Oscillatory suction was highly dependent on dimensionless frequency ( F +) based on the distance from the flow control slot to the flap trailing edge; the pressures on the central portion of the flap increased for F + ? 0.11 and then decreased for greater F +; finally attained negative pressures at F + = 0.44. The increase in jet momentum and turbulence intensity, combined with the induced streamwise vorticity, makes steady suction a potential concept for increasing propulsion efficiency through vortex-enhanced mixing. The flow control methods modify the jet flow, which in turn would alter the jet noise spectra.

Depuru Mohan, N. K.; Greenblatt, D.; Nayeri, C. N.; Paschereit, C. O.; Panchapakesan, N. R.

2015-03-01

341

Determination of optimum minimum flow from a dam by using energy analysis  

NASA Astrophysics Data System (ADS)

The proposed restoration of an abandoned hydroelectric dam on the Quinebaug River, Connecticut, is studied using energy analysis. The analysis considers the effects of alternative minimum flow releases, ranging from 0 to 34 cubic meters per second (cms), on the total energy flow of the affected system. The principal system components affected by differing minimum flows are hydroelectric power generation, aquatic habitat, and gross aquatic ecosystem productivity. The minimum flow alternative resulting in the highest annual energy flow in the affected system is considered optimal. From this purely analytical point of view, the optimum minimum flow is 0 cms, due to the short length and low productivity of the regulated reach, and the lack of floodplain interactions. Simulations of longer and more productive river reaches were conducted. For very short, unproductive reaches, in the absence of a floodplain, the contribution of aquatic community productivity to total system energy flow is negligible compared to hydroelectric generation. Optimum minimum flows are higher for longer and more productive reaches. For such cases the operation of hydroelectric dams could reduce total system energy flow because the energy supplied by hydroelectric generation may be offset by losses in aquatic productivity due to diminished riverine habitat.

Williams, James B.; McKellar, Henry N.

1984-07-01

342

Design Flexibility of Redox Flow Systems. [for energy storage applications  

NASA Technical Reports Server (NTRS)

The characteristics inherent in Redox flow systems permit considerable latitude in designing systems for specific storage applications. The first of these characteristics is the absence of plating/deplating reactions with their attendant morphology changes at the electrodes. This permits a given Redox system to operate over a wide range of depths of discharge and charge/discharge rates. The second characteristic is the separation of power generating components (stacks) from the energy storage components (tanks). This results in cost effective system design, ease of system growth via modularization, and freedom from sizing restraints so that the whole spectrum of applications, from utilities down to single residence can be considered. The final characteristic is the commonality of the reactant fluids which assures that all cells at all times are receiving reactants at the same state of charge. Since no cell can be out of balance with respect to any other cell, it is possible for some cells to be charged while others are discharging, in effect creating a DC to DC transformer. It is also possible for various groups of cells to be connected to separate loads, thus supplying a range of output voltages. Also, trim cells can be used to maintain constant bus voltage as the load is changed or as the depth of discharge increases. The commonality of reactant fluids also permits any corrective measures such as rebalancing to occur at the system level instead of at the single cell level.

Hagedorn, N. H.; Thaller, L. H.

1982-01-01

343

Distributed Energy Communications & Controls, Lab Activities - Summary  

SciTech Connect

The purpose is to develop controls for inverter-based renewable and non-renewable distributed energy systems to provide local voltage, power and power quality support for loads and the power grid. The objectives are to (1) develop adaptive controls for inverter-based distributed energy (DE) systems when there are multiple inverters on the same feeder and (2) determine the impact of high penetration high seasonal energy efficiency ratio (SEER) air conditioning (A/C) units on power systems during sub-transmission faults which can result in an A/C compressor motor stall and assess how inverter-based DE can help to mitigate the stall event. The Distributed Energy Communications & Controls Laboratory (DECC) is a unique facility for studying dynamic voltage, active power (P), non-active power (Q) and power factor control from inverter-based renewable distributed energy (DE) resources. Conventionally, inverter-based DE systems have been designed to provide constant, close to unity power factor and thus not provide any voltage support. The DECC Lab interfaces with the ORNL campus distribution system to provide actual power system testing of the controls approach. Using mathematical software tools and the DECC Lab environment, we are developing and testing local, autonomous and adaptive controls for local voltage control and P & Q control for inverter-based DE. We successfully tested our active and non-active power (P,Q) controls at the DECC laboratory along with voltage regulation controls. The new PQ control along with current limiter controls has been tested on our existing inverter test system. We have tested both non-adaptive and adaptive control modes for the PQ control. We have completed several technical papers on the approaches and results. Electric power distribution systems are experiencing outages due to a phenomenon known as fault induced delayed voltage recovery (FIDVR) due to air conditioning (A/C) compressor motor stall. Local voltage collapse from FIDVR is occurring in part because modern air-conditioner and heat pump compressor motors are much more susceptible to stalling during a voltage sag or dip than older motors. These motors can stall in less than three cycles (0.05 s) when a fault, for example, on the sub-transmission system, causes voltage on the distribution system to sag to 70% or less of nominal. We completed a new test system for A/C compressor motor stall testing at the DECC Lab. The A/C Stall test system is being used to characterize when and how compressor motors stall under low voltage and high compressor pressure conditions. However, instead of using air conditioners, we are using high efficiency heat pumps. We have gathered A/C stall characterization data for both sustained and momentary voltage sags of the test heat pump. At low enough voltage, the heat pump stalls (compressor motor stops and draws 5-6 times normal current in trying to restart) due to low inertia and low torque of the motor. For the momentary sag, we are using a fast acting contactor/switch to quickly switch from nominal to the sagged voltage in cycles.

Rizy, D Tom [ORNL

2010-01-01

344

Two-phase refrigerant flow instability analysis and active control in transient electronics cooling systems  

E-print Network

Two-phase refrigerant flow instability analysis and active control in transient electronics cooling Pressure-drop oscillation Refrigeration system Two-phase cooling Active control Transient heat load a b s t r a c t Two-loop refrigeration systems are being explored for two-phase cooling of ultra high power

Peles, Yoav

345

Fluorescent flow cytometric assay: a new diagnostic tool for measuring ?-glucocerebrosidase activity in Gaucher disease  

Microsoft Academic Search

The purpose of this study was to determine glucocerebrosidase activity by a fluorescent flow cytometry method in patients and carriers of Gaucher disease, and in healthy controls, and correlate the results with the standard glucocerebrosidase assay in the same individuals. Biochemical diagnosis has heretofore been performed by measuring enzyme activity using a fluorimetric assay method with cell lysate. We present

Bernard Rudensky; Esther Paz; Gheona Altarescu; David Raveh; Deborah Elstein; Ari Zimran

2003-01-01

346

Activation of G proteins mediates flow-induced prostaglandin E2 production in osteoblasts  

NASA Technical Reports Server (NTRS)

Interstitial fluid flow may play a role in load-induced bone remodeling. Previously, we have shown that fluid flow stimulates osteoblast production of cAMP inositol trisphosphate (IP3), and PGE2. Flow-induced increases in cAMP and IP3 were shown to be a result of PG production. Thus, PGE2 production appears to be an important component in fluid flow induced signal transduction. In the present study, we investigated the mechanism of flow-induced PGE2 synthesis. Flow-induced a 20-fold increase in PGE2 production in osteoblasts. Increases were also observed with ALF4-(10mM) (98-fold), an activator of guanidine nucleotide-binding proteins (G proteins), and calcium ionophore A23187 (2 microM) (100-fold) in stationary cells. We then investigated whether flow stimulation is mediated by G proteins and increases in intracellular calcium. Flow-induced PGE2 production was inhibited by the G protein inhibitors GDP beta S (100 microM) and pertussis toxin (1 microgram/ml) by 83% and 72%, respectively. Chelation of extracellular calcium by EGTA (2 mM) and intracellular calcium by quin-2/AM (30 microM) blocked flow stimulation by 87% and 67%, respectively. These results suggest that G proteins and calcium play an important role in mediating mechanochemical signal transduction in osteoblasts.

Reich, K. M.; McAllister, T. N.; Gudi, S.; Frangos, J. A.

1997-01-01

347

Separated Vs. homogeneous two-phase flow in violent strombolian activity  

NASA Astrophysics Data System (ADS)

The term "violent Strombolian" was first used to describe mafic eruptions that formed ash-charged columns up to 6 km high, and dispersed material up to a few hundred km from the source (Walker, 1971). These eruptions are often discontinuous and strongly pulsatory and are typically associated with simultaneous effusive activity: they form composite deposits constituted by a cinder cone, tephra blanket, and lava flows spreading from lateral vents. This eruptive regime is typical of water-rich mafic magmas and is characterized by average mass flows (103-105 kg/s) intermediate between Hawaiian and subplinian regimes. Within this interval, there is a direct correlation between explosivity, as defined by tephra production, and magma flux. When magma flow exceeds 105 kg/s, gas segregation is no longer possible and eruptive activity takes the form of sustained columns (subplinian to plinian activity). At eruption rates below 103 kg/s passive degassing processes dominate, causing lava effusion and/or mild explosive activity (Strombolian to Hawaiian). We suggest that very shallow gas segregation processes play a fundamental role in violent strombolian dynamics, affecting both explosive and effusive activity. Simultaneous eruption of tephra from the cone and lava flows from lateral vents requires both a gas-rich mixture ascending the central conduit and gas-poor lava flowing in the lateral system. Uneven distribution of liquid and gas phases is possible only when gas and magma are characterized by different momentum, i.e. the flow is separated. At a first approximation, the phase distribution is controlled by the two-phase flow regime (bubbly, slug, churn or annular), both gas and liquid fluxes, and the ratio between conduit and dike diameters. To quantify this process, we analyze in detail the dynamics of a particularly long-lived and well-known eruption of the last century- the Paricutin eruption (1943-1952) of central Mexico. Specific two-phase flow models are then used to evaluate 1) the effect of separated flow in magma splitting between a central conduit and a lateral dike system, 2) the flow regime that can develop in the central conduit 3) the potential effect on the explosive dynamics. Our results indicate that the explosivity of the eruption was strongly increased by segregation processes, promoting shallow fragmentation of the magma, and that the pulsatory dynamics was likely related to unstable, transitional two-phase flow regimes typical of gas fluxes intermediate between slug and annular flow.

Pioli, L.; Cashman, K.; Wallace, P.

2007-12-01

348

Generalization and extension of the law of acoustic energy conservation in a nonuniform flow  

Microsoft Academic Search

An exact conservation equation is derived which generalizes the familiar acoustic energy equations. The new relation is valid for arbitrary disturbances to a viscous, compressible flow. It is suggested by a development of the acoustic energy equation by means of a regular perturbation expansion of the general energy equation of fluid mechanics. A perturbation energy density and flux are defined

M. K. Myers

1986-01-01

349

Energy and materials flows in the production of liquid and gaseous oxygen  

Microsoft Academic Search

Liquid and gaseous oxygen is produced in an energy-intensive air separation processo that also generates nitrogen. More than 65% of the cost of oxygen is attributable to energy costs. Energy use and materials flows are analyzed for various air separation methods. Effective approaches to energy and material conservation in air separation plants include efficient removal of contaminants (carbon dioxide and

S. Shen; A. M. Wolsky

1980-01-01

350

A Practical Flow Control Scheme Considering Optimal Energy Allocation in Solar-Powered WSNs  

Microsoft Academic Search

Using solar power in wireless sensor networks (WSNs) requires a different approach to energy consumption from networks with battery-based nodes. Since solar energy can be harvested periodically, our aim is to use this harvested energy efficiently for specific network-wide performance goals, not just to minimize the energy consumption to sustain the network lifetime. Therefore, we propose a flow control algorithm

Dong Kun Noh; Kyungtae Kang

2009-01-01

351

Luminal flow modulates H+-ATPase activity in the cortical collecting duct (CCD).  

PubMed

Epithelial Na(+) channel (ENaC)-mediated Na(+) absorption and BK channel-mediated K(+) secretion in the cortical collecting duct (CCD) are modulated by flow, the latter requiring an increase in intracellular Ca(2+) concentration ([Ca(2+)](i)), microtubule integrity, and exocytic insertion of preformed channels into the apical membrane. As axial flow modulates HCO(3)(-) reabsorption in the proximal tubule due to changes in both luminal Na(+)/H(+) exchanger 3 and H(+)-ATPase activity (Du Z, Yan Q, Duan Y, Weinbaum S, Weinstein AM, Wang T. Am J Physiol Renal Physiol 290: F289-F296, 2006), we sought to test the hypothesis that flow also regulates H(+)-ATPase activity in the CCD. H(+)-ATPase activity was assayed in individually identified cells in microperfused CCDs isolated from New Zealand White rabbits, loaded with the pH-sensitive dye BCECF, and then subjected to an acute intracellular acid load (NH(4)Cl prepulse technique). H(+)-ATPase activity was defined as the initial rate of bafilomycin-inhibitable cell pH (pH(i)) recovery in the absence of luminal K(+), bilateral Na(+), and CO(2)/HCO(3)(-), from a nadir pH of ?6.2. We found that 1) an increase in luminal flow rate from ?1 to 5 nl·min(-1)·mm(-1) stimulated H(+)-ATPase activity, 2) flow-stimulated H(+) pumping was Ca(2+) dependent and required microtubule integrity, and 3) basal and flow-stimulated pH(i) recovery was detected in cells that labeled with the apical principal cell marker rhodamine Dolichos biflorus agglutinin as well as cells that did not. We conclude that luminal flow modulates H(+)-ATPase activity in the rabbit CCD and that H(+)-ATPases therein are present in both principal and intercalated cells. PMID:21957178

Liu, Wen; Pastor-Soler, Núria M; Schreck, Carlos; Zavilowitz, Beth; Kleyman, Thomas R; Satlin, Lisa M

2012-01-01

352

Experimental investigation of active rib stitch knitted architecture for flow control applications  

NASA Astrophysics Data System (ADS)

Actively manipulating flow characteristics around the wing can enhance the high-lift capability and reduce drag; thereby, increasing fuel economy, improving maneuverability and operation over diverse flight conditions which enables longer, more varied missions. Active knits, a novel class of cellular structural smart material actuator architectures created by continuous, interlocked loops of stranded active material, produce distributed actuation that can actively manipulate the local surface of the aircraft wing to improve flow characteristics. Rib stitch active knits actuate normal to the surface, producing span-wise discrete periodic arrays that can withstand aerodynamic forces while supplying the necessary displacement for flow control. This paper presents a preliminary experimental investigation of the pressuredisplacement actuation performance capabilities of a rib stitch active knit based upon shape memory alloy (SMA) wire. SMA rib stitch prototypes in both individual form and in stacked and nestled architectures were experimentally tested for their quasi-static load-displacement characteristics, verifying the parallel and series relationships of the architectural configurations. The various configurations tested demonstrated the potential of active knits to generate the required level of distributed surface displacements while under aerodynamic level loads for various forms of flow control.

Abel, Julianna M.; Mane, Poorna; Pascoe, Benjamin; Luntz, Jonathan; Brei, Diann

2010-04-01

353

Stress-Activated Electric Currents in the Earth Crust: How they Can and Cannot Flow (Invited)  

NASA Astrophysics Data System (ADS)

Dormant electronic charge carriers exist in rocks. They “wake up” when stresses are applied: electrons e’ and positive holes, h., the latter being defect electrons in the oxygen anion sublattice of minerals [1, 2]. The h. can flow out of the stressed subvolume. They can spread into the unstressed surrounding, turning the rocks into p-type semiconductors. They travel fast and far using energy levels at the upper edge of the valence bands. Contrary to the h., the co-activated electrons e’ cannot flow out and propagate through unstressed rocks: they are stuck in the activation volume. The situation is akin to that in an electrochemical battery except that, in the “rock battery”, the positive charge carriers are not cations but positive holes h.. In the laboratory it is easy to close the battery circuit by offering the electrons a metal contact and connecting the stressed and unstressed rock with a metal wire. This is useful to demonstrate the functioning of the “rock battery”. In the field the h. outflow from a stressed rock volume is restricted as long as there is no return path. This is an important point when we try to understand why pre-earthquake EM emission is widely considered “unreliable” [3, 4]. However, there are at least three conditions, under which circuit closure can be achieved in the field under realistic pre-earthquake situations: (i) via n-type conducting rocks; (ii) via electrolytic conductivity of water; and (iii) via the air when the air above the epicentral region becomes highly ionized. We report on examples where these three conditions might have allowed large currents to flow and strong EM signals to be emitted. [1] Freund, F.T. et al.: Electric currents streaming out of stressed igneous rocks - A step towards understanding pre-earthquake low frequency EM emissions, Phys. Chem. Earth 31, 389-396 (2006). [2] Freund, F.T.: Charge generation and propagation in rocks, J. Geodyn. 33, 545-572 (2002). [3] Johnston, M.J.S. and Parrot, M.: Seismoelectromagnetic Effects, Phys. Earth Planet. Inter. 57, 1-177 (1989). [4] Park, S.K. et al.: The 2004 Parkfield earthquake: Test of the electromagnetic precursor hypothesis, J. Geophys, Res. 112, 10.1029/2005JB004196 (2007).

Freund, F. T.; Bleier, T. E.; Bortnik, J.; Dahlgren, R.

2010-12-01

354

Security constrained optimal power flow for an economical operation of FACTS-devices in liberalized energy markets  

Microsoft Academic Search

Among the ongoing liberalization of the global energy markets, several technical developments in the field of power electronic based transmission devices lead to a significant restructuring of the electric power supply. These FACTS-devices (Flexible A_C T_ransmission S_stems) enable a continuous and wear-resistant control of active and reactive power flows as well as voltage control. The incorporation of the control capabilities

Carsten Lehmköster

2002-01-01

355

Closed Loop Active Flow Separation Detection and Control in a Multistage Compressor  

NASA Technical Reports Server (NTRS)

Active closed loop flow control was successfully demonstrated on a full annulus of stator vanes in a low speed axial compressor. Two independent methods of detecting separated flow conditions on the vane suction surface were developed. The first technique detects changes in static pressure along the vane suction surface, while the second method monitors variation in the potential field of the downstream rotor. Both methods may feasibly be used in future engines employing embedded flow control technology. In response to the detection of separated conditions, injection along the suction surface of each vane was used. Injected mass flow on the suction surface of stator vanes is known to reduce separation and the resulting limitation on static pressure rise due to lowered diffusion in the vane passage. A control algorithm was developed which provided a proportional response of the injected mass flow to the degree of separation, thereby minimizing the performance penalty on the compressor system.

Bright, Michelle M.; Culley, Dennis E.; Braunscheidel, Edward P.; Welch, Gerard E.

2005-01-01

356

Flow instability of a centrifugal pump determined using the energy gradient method  

NASA Astrophysics Data System (ADS)

The stability of the centrifugal pump has not been well revealed because of the complexity of internal flow. To analyze the flow characteristics of a centrifugal pump operating at low capacity, methods of numerical simulation and experimental research were adopted in this paper. Characteristics of the inner flow were obtained. Standard k-? turbulence models were used to calculate the inner flow of the pump under off-design conditions. The distribution of the energy gradient function K was obtained by three-dimensional numerical simulation at different flow rates. The relative velocity component was acquired from the absolute velocity obtained in particle image velocimetry. By comparing with experimental results, it was found that flow instability occurs at the position of maximum K. The flow stability reduces with an increasing flow rate. The research results provide a theoretical basis for the optimization design of a centrifugal pump.

Li, Yi; Dong, Wenlong; He, Zhaohui; Huang, Yuanmin; Jiang, Xiaojun

2015-02-01

357

Dynamic simulation of energy consumption in mixed traffic flow considering highway toll station  

NASA Astrophysics Data System (ADS)

An improved model of energy consumption including toll station is presented in this paper. Using the model, we study the influences of mixed ratio, the idling energy consumption of vehicle, vehicle peak velocity, dwell time and random deceleration probability on energy consumption of Electronic Toll Collection or Manual Toll Collection mixed traffic flow on single lane under periodic condition. Simulating results indicate that the above five parameters are all increasing functions of total energy consumption, in which the idling energy consumption represents the major amounts with the increase of mixed ratio and occupancy rate. Thus, the existence of toll station has significant effect on the energy consumption of mixed traffic flow.

Qian, Yong-Sheng; Zhang, Xiao-Long; Zeng, Jun-Wei; Shao, Xiao-Ming; Wang, Neng

2015-01-01

358

Active noise cancellation in a waveguide in the presence of flow  

NASA Astrophysics Data System (ADS)

Active sound cancellation in a waveguide by applying a receiver-emitter placed on the waveguide wall in the presence of a constant-velocity flow in the waveguide is studied. The acoustic field propagating inside the waveguide together with the flow is measured and used to determine the amplitudes and phases of auxiliary emitters whose field is applied to suppress the incident field in the waveguide.

Ivanov, V. P.

2013-07-01

359

Sensitive Flow Cytometric Method to Test Basophil Activation Influenced by Homeopathic Histamine Dilutions  

Microsoft Academic Search

SummaryObjective: In an experimental setting, human basophil degranulation was triggered by anti-IgE to measure the effects from homeopathic solutions in an in-vitro cell system. A 3-color flow cytometric method with enhanced accuracy was established. As an example we looked at the influence of histamine on anti-IgE activation of basophils. Methods: Basophils were identified in the flow cytometer by their physical

I. Lorenz; E. M. Schneider; P. Stolz; A. Brack; J. Strube

2003-01-01

360

Subsurface Flows near Four Emerging Active Regions Studied with Ring-Diagram Analysis  

Microsoft Academic Search

We study the temporal variation of subsurface flows associated with four emerging active regions. Two of them, AR~10314 and AR~10488, emerge near disk center and the other two, AR~10365 and AR~10375, are older regions where new flux emerges during their disk passage. We measure the horizontal subsurface flows from high-resolution Global Oscillation Network Group (GONG+) data using ring-diagram analysis and

R. Komm; R. Howe; F. Hill; S. Morita

2008-01-01

361

TEMPO-based catholyte for high-energy density nonaqueous redox flow batteries.  

PubMed

A TEMPO-based non-aqueous electrolyte with the TEMPO concentration as high as 2.0 m is demonstrated as a high-energy-density catholyte for redox flow battery applications. With a hybrid anode, Li|TEMPO flow cells using this electrolyte deliver an energy efficiency of ca. 70% and an impressively high energy density of 126 W h L(-1) . PMID:25327755

Wei, Xiaoliang; Xu, Wu; Vijayakumar, Murugesan; Cosimbescu, Lelia; Liu, Tianbiao; Sprenkle, Vincent; Wang, Wei

2014-12-01

362

Comparison of energy flows in deep inelastic scattering events with and without a large rapidity gap  

Microsoft Academic Search

Energy flows in deep inelastic electron-proton scattering are investigated at a centre-of-mass energy of 269 GeV for the range Q2 >= 10 GeV2 using the ZEUS detector. A comparison is made between events with and without a large rapidity gap between the hadronic system and the proton direction. The energy flows, corrected for detector acceptance and resolution, are shown for

M. Derrick; D. Krakauer; S. Magill; B. Musgrave; J. Repond; J. Schlereth; R. Stanek; R. L. Talaga; J. Thron; F. Arzarello; R. Ayad; G. Bari; M. Basile; L. Bellagamba; D. Boscherini; A. Bruni; G. Bruni; P. Bruni; G. Cara Romeo; G. Castellini; M. Chiarini; L. Cifarelli; F. Cindolo; F. Ciralli; A. Contin; S. D'Auria; C. del Papa; F. Frasconi; P. Giusti; G. Iacobucci; G. Laurenti; G. Levi; G. Maccarrone; A. Margotti; T. Massam; R. Nania; C. Nemoz; F. Palmonari; A. Polini; G. Sartorelli; R. Timellini; Y. Zamora Garcia; A. Zichichi; A. Bargende; J. Crittenden; K. Desch; B. Diekmann; T. Doeker; L. Feld; A. Frey; M. Geerts; G. Geitz; M. Grothe; H. Hartmann; D. Haun; K. Heinloth; E. Hilger; H.-P. Jakob; U. F. Katz; S. M. Mari; A. Mass; S. Mengel; J. Mollen; E. Paul; Ch. Rembser; R. Schattevoy; J.-L. Schneider; D. Schramm; J. Stamm; R. Wedemeyer; S. Campbell-Robson; A. Cassidy; N. Dyce; B. Foster; S. George; R. Gilmore; G. P. Heath; H. F. Heath; T. J. Llewellyn; C. J. S. Morgado; D. J. P. Norman; J. A. O'Mara; R. J. Tapper; S. S. Wilson; R. Yoshida; R. R. Rau; M. Arneodo; L. Iannotti; M. Schioppa; G. Susinno; A. Bernstein; A. Caldwell; I. Gialas; J. A. Parsons; S. Ritz; F. Sciulli; P. B. Straub; L. Wai; S. Yang; P. Borzemski; J. Chwastowski; A. Eskreys; K. Piotrzkowski; M. Zachara; L. Zawiejski; L. Adamczyk; B. Bednarek; K. Eskreys; K. Jelen; D. Kisielewska; T. Kowalski; E. Rulikowska-Zarebska; L. Suszycki; J. Zajc; T. Kedzierski; A. Kotanski; M. Przybycien; L. A. T. Bauerdick; U. Behrens; J. K. Bienlein; S. Böttcher; C. Coldewey; G. Drews; M. Flasinski; D. J. Gilkinson; P. Göttlicher; B. Gutjahr; T. Haas; L. Hagge; W. Hain; D. Hasell; H. Heßling; H. Hultschig; Y. Iga; P. Joos; M. Kasemann; R. Klanner; W. Koch; L. Köpke; U. Kötz; H. Kowalski; W. Kröger; J. Krüger; J. Labs; A. Ladage; B. Löhr; M. Löwe; D. Lüke; J. Mainusch; O. Manczak; J. S. T. Ng; S. Nickel; D. Notz; K. Ohrenberg; M. Roco; M. Rohde; J. Roldán; U. Schneekloth; J. Schroeder; W. Schulz; F. Selonke; E. Stiliaris; T. Voß; D. Westphal; G. Wolf; C. Youngman; H. J. Grabosch; A. Leich; A. Meyer; C. Rethfeldt; S. Schlenstedt; G. Barbagli; P. Pelfer; G. Anzivino; S. de Pasquale; S. Qian; L. Votano; A. Bamberger; A. Freidhof; T. Poser; S. Söldner-Rembold; G. Theisen; T. Trefzger; N. H. Brook; P. J. Bussey; A. T. Doyle; I. Fleck; J. R. Forbes; V. A. Jamieson; C. Raine; D. H. Saxon; M. Stavrianakou; A. S. Wilson; A. Dannemann; U. Holm; D. Horstmann; H. Kammerlocher; B. Krebs; T. Neumann; R. Sinkus; K. Wick; E. Badura; B. D. Burow; A. Fürtjes; E. Lohrmann; J. Milewski; M. Nakahata; N. Pavel; G. Poelz; W. Schott; J. Terron; F. Zetsche; T. C. Bacon; R. Beuselinck; I. Butterworth; E. Gallo; V. L. Harris; B. H. Hung; K. R. Long; D. B. Miller; P. P. O. Morawitz; A. Prinias; J. K. Sedgbeer; A. F. Whitfield; U. Mallik; E. McCliment; M. Z. Wang; Y. Zhang; P. Cloth; D. Filges; S. H. An; S. M. Hong; C. O. Kim; T. Y. Kim; S. W. Nam; S. K. Park; M. H. Suh; S. H. Yon; R. Imlay; S. Kartik; H.-J. Kim; R. R. McNeil; W. Metcalf; V. K. Nadendla; F. Barreiro; G. Cases; R. Graciani; J. M. Hernández; L. Hervás; L. Labarga; J. del Peso; J. Puga; J. F. de Trocóniz; F. Ikraiam; J. K. Mayer; G. R. Smith; F. Corriveau; D. S. Hanna; J. Hartmann; L. W. Hung; J. N. Lim; C. G. Matthews; J. W. Mitchell; P. M. Patel; L. E. Sinclair; D. G. Stairs; M. St. Laurent; R. Ullmann; V. Bashkirov; B. A. Dolgoshein; A. Stifutkin; G. L. Bashindzhagyan; P. F. Ermolov; L. K. Gladilin; Y. A. Golubkov; V. D. Kobrin; V. A. Kuzmin; A. S. Proskuryakov; A. A. Savin; L. M. Shcheglova; A. N. Solomin; N. P. Zotov; S. Bentvelsen; M. Botje; F. Chlebana; A. Dake; J. Engelen; P. de Jong; M. de Kamps; P. Kooijman; A. Kruse; V. O'dell; A. Tenner; H. Tiecke; W. Verkerke; M. Vreeswijk; L. Wiggers; E. de Wolf; R. van Woudenberg; D. Acosta; B. Bylsma; L. S. Durkin; K. Honscheid; C. Li; T. Y. Ling; K. W. McLean; W. N. Murray; I. H. Park; T. A. Romanowski; R. Seidlein; D. S. Bailey; G. A. Blair; A. Byrne; R. J. Cashmore; A. M. Cooper-Sarkar; D. Daniels; R. C. E. Devenish; N. Harnew; M. Lancaster; P. E. Luffman; J. McFall; C. Nath; A. Quadt; H. Uijterwaal; R. Walczak; F. F. Wilson; T. Yip; G. Abbiendi; A. Bertolin; R. Brugnera; R. Carlin; F. dal Corso; M. de Giorgi; U. Dosselli; F. Gasparini; S. Limentani; M. Morandin; M. Posocco; L. Stanco; R. Stroili; C. Voci; J. Bulmahn; J. M. Butterworth; R. G. Feild; B. Y. Oh; J. J. Whitmore; G. D'Agostini; M. Iori; G. Marini; M. Mattioli; A. Nigro; J. C. Hart; N. A. McCubbin; K. Prytz; T. P. Shah; T. L. Short; E. Barberis; N. Cartiglia; T. Dubbs; C. Heusch; M. van Hook; B. Hubbard; W. Lockman; H. F.-W. Sadrozinski; A. Seiden; J. Biltzinger; R. J. Seifert; A. H. Walenta; G. Zech; H. Abramowicz; S. Dagan; A. Levy; T. Hasegawa; M. Hazumi; T. Ishii; M. Kuze; S. Mine; Y. Nagasawa; T. Nagira; M. Nakao; I. Suzuki; K. Tokushuku; S. Yamada

1994-01-01

363

Pulsed-flow air classification for waste to energy production. Final report  

SciTech Connect

The development and testing of pulsed-flow air classification for waste-to-energy production are discussed. Standard designs generally permit large amounts of combustible material to escape as reject while producing a fuel that is high in metal and glass contaminants. Pulsed-flow classification is presented as a concept which can avoid both pitfalls. Each aspect of theory and laboratory testing is summarized: particle characteristics, theory of pulsed-flow classification, laboratory testing, and pulsed-flow air classification for waste-to-energy production. Conclusions from the research are summarized.

Peirce, J.J.; Vesilind, P.A.

1983-09-30

364

Nonlinear energy transfers and phase diagrams for geostrophically balanced rotating-stratified flows  

NASA Astrophysics Data System (ADS)

Equilibrium statistical mechanics tools have been developed to obtain indications about the natural tendencies of nonlinear energy transfers in two-dimensional and quasi-two-dimensional flows like rotating and stratified flows in geostrophic balance. In this article we consider a simple model of such flows with a nontrivial vertical structure, namely, two-layer quasigeostrophic flows, which remain amenable to analytical study. We obtain the statistical equilibria of the system in the case of a linear vorticity-stream function relation, build the corresponding phase diagram, and discuss the most probable outcome of nonlinear energy transfers, both on the horizontal and on the vertical, in the presence of stratification and rotation.

Herbert, Corentin

2014-03-01

365

Active Fail-Safe Micro-Array Flow Control for Advanced Embedded Propulsion Systems  

NASA Technical Reports Server (NTRS)

The primary objective of this research effort was to develop and analytically demonstrate enhanced first generation active "fail-safe" hybrid flow-control techniques to simultaneously manage the boundary layer on the vehicle fore-body and to control the secondary flow generated within modern serpentine or embedded inlet S-duct configurations. The enhanced first-generation technique focused on both micro-vanes and micro-ramps highly-integrated with micro -jets to provide nonlinear augmentation for the "strength' or effectiveness of highly-integrated flow control systems. The study focused on the micro -jet mass flow ratio (Wjet/Waip) range from 0.10 to 0.30 percent and jet total pressure ratios (Pjet/Po) from 1.0 to 3.0. The engine bleed airflow range under study represents about a 10 fold decrease in micro -jet airflow than previously required. Therefore, by pre-conditioning, or injecting a very small amount of high-pressure jet flow into the vortex generated by the micro-vane and/or micro-ramp, active flow control is achieved and substantial augmentation of the controlling flow is realized.

Anderson, Bernhard H.; Mace, James L.; Mani, Mori

2009-01-01

366

Energy Around Us. A Fall Activity Packet for Fourth Grade.  

ERIC Educational Resources Information Center

This instructional packet is one of 14 school environmental education programs developed for use in the classroom and at the Dahlem Environmental Education Center (DEEC) of the Jackson Community College (Michigan). Provided in the packet are pre-trip activities, field trip activities, and post-trip activities which focus on energy uses, energy…

Jackson Community Coll., MI. Dahlem Environmental Education Center.

367

Instantaneous Average Active Power Measurement For Building Energy Management System  

Microsoft Academic Search

Fast and accurate measurement of the instantaneous average active power is useful for building Energy Management System (EMS) in order to assure quality of service such as continuity, optimize energy consumption and reduce carbon dioxide emission. In this paper the problems connected to the measurement of the instantaneous average active power for energy usage improving are discussed, also as the

R. Micheletti; R. Pieri

368

Selected Energy Education Activities for Pennsylvania Middle School Grades. Draft.  

ERIC Educational Resources Information Center

These activities are intended to help increase awareness and understanding of the energy situation and to encourage students to become energy conservationists. The document is divided into sections according to discipline area. A final section is devoted to interdisciplinary activities involving several discipline areas integrated with the energy…

Hack, Nancy; And Others

369

Sample Energy Conservation Education Activities for Elementary School Students.  

ERIC Educational Resources Information Center

The booklet contains learning activities for introducing energy and conservation concepts into the existing elementary school curriculum. The activities were developed by Palm Beach County teachers during a one-week workshop. A framework of ideas is divided into three functional categories: universe of energy, living systems and energy, and social…

Allen, Rodney F., Ed.; LaHart, David E., Ed.

370

Hot-Film and Hot-Wire Anemometry for a Boundary Layer Active Flow Control Test  

NASA Technical Reports Server (NTRS)

Unsteady active flow control (AFC) has been used experimentally for many years to minimize bluff-body drag. This technology could significantly improve performance of rotorcraft by cleaning up flow separation. It is important, then, that new actuator technologies be studied for application to future vehicles. A boundary layer wind tunnel was constructed with a 1ft-x-3ft test section and unsteady measurement instrumentation to study how AFC manipulates the boundary layer to overcome adverse pressure gradients and flow separation. This unsteady flow control research requires unsteady measurement methods. In order to measure the boundary layer characteristics, both hot-wire and hot-film Constant Temperature Anemometry is used. A hot-wire probe is mounted in the flow to measure velocity while a hot-film array lays on the test surface to measure skin friction. Hot-film sensors are connected to an anemometer, a Wheatstone bridge circuit with an output that corresponds to the dynamic flow response. From this output, the time varying flow field, turbulence, and flow reversal can be characterized. Tuning the anemometers requires a fan test on the hot-film sensors to adjust each output. This is a delicate process as several variables drastically affect the data, including control resistance, signal input, trim, and gain settings.

Lenahan, Keven C.; Schatzman, David M.; Wilson, Jacob Samuel

2013-01-01

371

FLOWS AT THE EDGE OF AN ACTIVE REGION: OBSERVATION AND INTERPRETATION  

SciTech Connect

Upflows observed at the edges of active regions have been proposed as the source of the slow solar wind. In the particular case of Active Region (AR) 10942, where such an upflow has been already observed, we want to evaluate the part of this upflow that actually remains confined in the magnetic loops that connect AR 10942 to AR 10943. Both active regions were visible simultaneously on the solar disk and were observed by STEREO/SECCHI EUVI. Using Hinode/EIS spectra, we determine the Doppler shifts and densities in AR 10943 and AR 10942 in order to evaluate the mass flows. We also perform magnetic field extrapolations to assess the connectivity between AR 10942 and AR 10943. AR 10943 displays a persistent downflow in Fe XII. Magnetic extrapolations including both ARs show that this downflow can be connected to the upflow in AR 10942. We estimate that the mass flow received by AR 10943 areas connected to AR 10942 represents about 18% of the mass flow from AR 10942. We conclude that the upflows observed on the edge of active regions represent either large-scale loops with mass flowing along them (accounting for about one-fifth of the total mass flow in this example) or open magnetic field structures where the slow solar wind originates.

Boutry, C.; Buchlin, E.; Vial, J.-C. [Universite Paris Sud, Institut d'Astrophysique Spatiale, UMR8617, 91405 Orsay (France); Regnier, S., E-mail: eric.buchlin@ias.u-psud.fr [Jeremiah Horrocks Institute, University of Central Lancashire, Preston, PR1 2HE (United Kingdom)

2012-06-10

372

The Cooling Rate of an Active Aa Lava Flow Determined Using an Orbital Imaging Spectrometer  

NASA Astrophysics Data System (ADS)

The surface temperature of an active lava flow is an important physical property to measure. Through its influence on lava crystallinity, cooling exerts a fundamental control on lava rheology. Remotely sensed thermal radiance data acquired by multispectral sensors such as Landsat Thematic Mapper and the Terra Advanced Spaceborne Thermal Emission and Reflection Radiometer, are of insufficient spectral and radiometric fidelity to allow for realistic determination of lava surface temperatures from Earth orbit. This paper presents results obtained from the analysis of active lava flows using hyperspectral data acquired by NASA's Earth Observing-1 Hyperion imaging spectrometer. The contiguous nature of the measured radiance spectrum in the 0.4-2.5 micron region means that, although sensor saturation most certainly occurs, unsaturated radiance data are always available from even the hottest, and most radiant, active lava flow surfaces. The increased number of wavebands available allows for the assumption of more complex flow surface temperature distributions in the radiance-to-temperature inversion processes. The technique is illustrated by using a hyperspectral image of the active lava lake at Erta Ale volcano, Ethiopia, a well characterized calibration target. We then go on to demonstrate how this approach can be used to constrain the surface cooling rate of an active lava flow at Mount Etna, Sicily, using three images acquired during a four day period in September 2004. The cooling rate of the active channel as determined from space falls within the limits commonly assumed in numerical lava flow models. The results provide insights into the temperature-radiance mixture modeling problem that will aid in the analysis of data acquired by future hyperspectral remote sensing missions, such as NASA's proposed HyspIRI mission.

Wright, Robert; Garbeil, Harold

2010-05-01

373

Modeling Hot Gas Flow in the Low-luminosity Active Galactic Nucleus of NGC 3115  

NASA Astrophysics Data System (ADS)

Based on the dynamical black hole (BH) mass estimates, NGC 3115 hosts the closest billion solar mass BH. Deep studies of the center revealed a very underluminous active galactic nucleus (AGN) immersed in an old massive nuclear star cluster. Recent 1 Ms Chandra X-ray visionary project observations of the NGC 3115 nucleus resolved hot tenuous gas, which fuels the AGN. In this paper we connect the processes in the nuclear star cluster with the feeding of the supermassive BH. We model the hot gas flow sustained by the injection of matter and energy from the stars and supernova explosions. We incorporate electron heat conduction as the small-scale feedback mechanism, the gravitational pull of the stellar mass, cooling, and Coulomb collisions. Fitting simulated X-ray emission to the spatially and spectrally resolved observed data, we find the best-fitting solutions with ?2/dof = 1.00 for dof = 236 both with and without conduction. The radial modeling favors a low BH mass <1.3 × 109 M ?. The best-fitting supernova rate and the best-fitting mass injection rate are consistent with their expected values. The stagnation point is at r st <~ 1'', so that most of the gas, including the gas at a Bondi radius rB = 2''-4'', outflows from the region. We put an upper limit on the accretion rate at 2 × 10-3 M ? yr-1. We find a shallow density profile nvpropr -? with ? ? 1 over a large dynamic range. This density profile is determined in the feeding region 0.''5-10'' as an interplay of four processes and effects: (1) the radius-dependent mass injection, (2) the effect of the galactic gravitational potential, (3) the accretion flow onset at r <~ 1'', and (4) the outflow at r >~ 1''. The gas temperature is close to the virial temperature Tv at any radius.

Shcherbakov, Roman V.; Wong, Ka-Wah; Irwin, Jimmy A.; Reynolds, Christopher S.

2014-02-01

374

Information Flow Model of Human Extravehicular Activity Operations  

NASA Technical Reports Server (NTRS)

Future human spaceflight missions will face the complex challenge of performing human extravehicular activity (EVA) beyond the low Earth orbit (LEO) environment. Astronauts will become increasingly isolated from Earth-based mission support and thus will rely heavily on their own decision-making capabilities and onboard tools to accomplish proposed EVA mission objectives. To better address time delay communication issues, EVA characters, e.g. flight controllers, astronauts, etc., and their respective work practices and roles need to be better characterized and understood. This paper presents the results of a study examining the EVA work domain and the personnel that operate within it. The goal is to characterize current and historical roles of ground support, intravehicular (IV) crew and EV crew, their communication patterns and information needs. This work provides a description of EVA operations and identifies issues to be used as a basis for future investigation.

Miller, Matthew J.; McGuire, Kerry M.; Feigh, Karen M.

2014-01-01

375

Kinetic model for the vibrational energy exchange in flowing molecular gas mixtures. Ph.D. Thesis  

NASA Technical Reports Server (NTRS)

The present study is concerned with the development of a computational model for the description of the vibrational energy exchange in flowing gas mixtures, taking into account a given number of energy levels for each vibrational degree of freedom. It is possible to select an arbitrary number of energy levels. The presented model uses values in the range from 10 to approximately 40. The distribution of energy with respect to these levels can differ from the equilibrium distribution. The kinetic model developed can be employed for arbitrary gaseous mixtures with an arbitrary number of vibrational degrees of freedom for each type of gas. The application of the model to CO2-H2ON2-O2-He mixtures is discussed. The obtained relations can be utilized in a study of the suitability of radiation-related transitional processes, involving the CO2 molecule, for laser applications. It is found that the computational results provided by the model agree very well with experimental data obtained for a CO2 laser. Possibilities for the activation of a 16-micron and 14-micron laser are considered.

Offenhaeuser, F.

1987-01-01

376

Active Control of Flow Separation on a High-Lift System with Slotted Flap at High Reynolds Number  

NASA Technical Reports Server (NTRS)

The NASA Energy Efficient Transport (EET) airfoil was tested at NASA Langley's Low- Turbulence Pressure Tunnel (LTPT) to assess the effectiveness of distributed Active Flow Control (AFC) concepts on a high-lift system at flight scale Reynolds numbers for a medium-sized transport. The test results indicate presence of strong Reynolds number effects on the high-lift system with the AFC operational, implying the importance of flight-scale testing for implementation of such systems during design of future flight vehicles with AFC. This paper describes the wind tunnel test results obtained at the LTPT for the EET high-lift system for various AFC concepts examined on this airfoil.

Khodadoust, Abdollah; Washburn, Anthony

2007-01-01

377

Energy and system size dependence of elliptic flow: using rapidity gaps to suppress non-flow contribution  

Microsoft Academic Search

In this talk I present new STAR results on measurements of integrated\\u000aelliptic flow at midrapidity in Au+Au and Cu+Cu collisions at\\u000a$\\\\sqrt{s_{NN}}=$200 and 62 GeV energies. These results have been obtained from\\u000aazimuthal correlations between particles in the main STAR TPC and two forward\\u000aTPCs, and are to a large extent free from so-called non-flow correlations.\\u000aThese results along

Sergei A. Voloshin

2006-01-01

378

Energy and system size dependence of elliptic flow: using rapidity gaps to suppress non-flow contribution  

E-print Network

In this talk I present new STAR results on measurements of integrated elliptic flow at midrapidity in Au+Au and Cu+Cu collisions at $\\sqrt{s_{NN}}=$200 and 62 GeV energies. These results have been obtained from azimuthal correlations between particles in the main STAR TPC and two forward TPCs, and are to a large extent free from so-called non-flow correlations. These results along with the previously reported values of ``participant'' eccentricity taking into account eccentricity fluctuations are used for testing the $v_2/\\eps$ scaling, which is found to hold relatively well.

Sergei A. Voloshin

2006-10-25

379

Collective Flow in Heavy Ion Collisions at Low to Relativistic Energies  

NASA Astrophysics Data System (ADS)

Recently, the phenomenon of collective flow in heavy ion collisions has been the subject of intense study. First observed at the Bevalac more than a decade ago, flow is now recognized as a universal feature of heavy ion collisions at all bombarding energies. Recent developments in three identified forms of flow-- sidewards flow, radial flow, and squeeze-out-- will be reviewed. At low energies (<50 A MeV), for which the nuclear mean field is attractive, the study of rotational flow leads to a better understanding of nuclear surface effects. Programs at MSU and GANIL (40-100 A MeV) have been performing detailed studies of the disappearance of sidewards flow, arising from the competition of the attractive mean field and repulsive nucleon-nucleon collisions; such studies have shown sensitivity to the in-medium N-N cross-section and momentum dependence of the mean field. At higher energy (0.25-2.0 A GeV), the EOS and FOPI collaborations have considerably extended the work begun by the Plastic Ball group; here, studies of the flow of nucleons, fragments, and pions lead to a better understanding of the Equation of State of nuclear matter, momentum dependent interactions, and pion shadowing. The squeeze-out effect at Bevalac energies may be the most sensitive form of flow to the equation of state. Recent studies suggest that squeeze-out may be considered as an azimuthal modulation of the radial flow. The E895 collaboration is continuing the flow excitation function of the EOS/FOPI groups for 2-10 A GeV bombarding energies, with the aim of increasing the sensitivity to Equation of State parameters, as well as searching for flow signatures of Quark Gluon Plasma creation. Sidewards flow at the highest AGS energy for Au beams(11 A GeV) has been reported by the E877 collaboration, which has correlated the effect with pion interferometry measurements to identify possible dynamical correlations in the collision. Finally, at the highest energies currently available, the NA49 collaboration has found sidewards flow at SPS energies (160 A GeV); preliminary comparisons to RQMD calculations indicate that the model reproduces the flow well. At all of these bombarding energies (over 3 orders of magnitude!), the particle spectra show a strong non-thermal component which has been identified as largely isotropic or "radial" flow. While the sidewards flow accounts for only ~5% of emitted particles' energy, roughly 30-50% of the energy of emitted particles is found in radial flow. Several groups are studying the implications of having such a large fraction of the energy in collective motion. Finally, spectral analyses accounting for the radial or outwards flow may suggest a leveling-off of the temperature and flow velocity around and above the highest AGS energies, which may be hint at a transition to QGP formation.

Lisa, M. A.

1997-04-01

380

All-Chromium Redox Flow Battery for Renewable Energy Storage  

Microsoft Academic Search

The charge\\/discharge characteristics of an undivided redox flow battery, using porous electrodes and chromium-EDTA electrolyte are discussed. The results indicate that a high current efficiency can be achieved using this system with single pass, flow through electrodes. With 0.2 M electrolytes and a charging current density of 30 mA cm, 100% current efficiency was achieved with 48% conversion of Cr(III)

Chulheung Bae; Edward Pelham Lindfield Roberts; Mohammed Harun Chakrabarti; Muhammad Saleem

2011-01-01

381

Waste-Lithium-Liquid (WLL) Flow Battery for Stationary Energy Storage Applications Youngsik Kim* and Nina MahootcheianAsl  

E-print Network

Waste-Lithium-Liquid (WLL) Flow Battery for Stationary Energy Storage Applications Youngsik Kim. The harvested Li metal could then be an energy source for Li-Liquid flow batteries by using water as the cathode in a Waste-Lithium-Liquid (WLL) flow battery that can be used in a stationary energy storage application. Li

Zhou, Yaoqi

382

Efficiency of energy separation at compressible gas flow in a planar duct  

NASA Astrophysics Data System (ADS)

The method of energy separation in a high-speed flow proposed by A.I. Leontyev is investigated numerically. The adiabatic compressible gas flow (of a helium-xenon mixture) with a low Prandtl number in a planar narrow duct and a flow with heat exchange in a duct partitioned by a heat-conducting wall are analysed. The temperature recovery factor on the adiabatic wall, degree of cooling the low-speed flow part, temperature efficiency, and the adiabatic efficiency in a duct with heat exchange are estimated. The data are obtained for the first time, which make it possible to compare the efficiency of energy separation in a high-speed flow with the efficiency of similar processes in vortex tubes and other setups of gas-dynamic energy separation.

Makarov, M. S.; Makarova, S. N.

2014-12-01

383

Efficiency of energy separation at compressible gas flow in a planar duct  

NASA Astrophysics Data System (ADS)

The method of energy separation in a high-speed flow proposed by A.I. Leontyev is investigated numerically. The adiabatic compressible gas flow (of a helium-xenon mixture) with a low Prandtl number in a planar narrow duct and a flow with heat exchange in a duct partitioned by a heat-conducting wall are analysed. The temperature recovery factor on the adiabatic wall, degree of cooling the low-speed flow part, temperature efficiency, and the adiabatic efficiency in a duct with heat exchange are estimated. The data are obtained for the first time, which make it possible to compare the efficiency of energy separation in a high-speed flow with the efficiency of similar processes in vortex tubes and other setups of gas-dynamic energy separation.

Makarov, M. S.; Makarova, S. N.

2013-12-01

384

Cooling rate of an active Hawaiian lava flow from nighttime spectroradiometer measurements  

NASA Technical Reports Server (NTRS)

A narrow-band spectroradiometer has been used to make nighttime measurements of the Phase 50 eruption of Pu'u O'o, on the East Rift Zone of Kilauea Volcano, Hawaii. On February 19, 1992, a GER spectroradiometer was used to determine the cooling rate of an active lava flow. This instrument collects 12-bit data between 0.35 to 3.0 microns at a spectral resolution of 1-5 nm. Thirteen spectra of a single area on a pahoehoe flow field were collected over a 59 minute period (21:27-22:26 HST) from which the cooling of the lava surface has been investigated. A two-component thermal mixing model (Flynn, 1992) applied to data for the flow immediately on emplacement gave a best-fit crustal temperature of 768 C, a hot component at 1150 C, and a hot radiating area of 3.6 percent of the total area. Over a 52-minute period (within the time interval between flow resurfacings) the lava flow crust cooled by 358 to 410 C at a rate that was as high as 15 C/min. The observations have significance both for satellite observations of active volcanoes and for numerical models of the cooling of lava flows during their emplacement.

Flynn, Luke P.; Mouginis-Mark, Peter J.

1992-01-01

385

Activation of serotonin 5-HT? receptor induces coronary flow increase in isolated rat heart.  

PubMed

Serotonin (5-Hydroxytryptamine, 5-HT) can elicit both vasoconstrictive and relaxant responses on rat coronary artery. The constrictive response has been well discussed, but the mechanism of relaxant response is less studied. In the present study, we found serotonin (0.3 and 1 ?M) increased coronary flow on isolated rat hearts, and treatment of nitric oxide synthase inhibitor NG-nitro-L-arginine methyl ester (L-NAME) 300 ?M reduced but not totally blocked this coronary flow increasing effect. In L-NAME 10 ?M treated heart, treatment of selective serotonin 5-HT? receptor antagonist SB269970 0.1 ?M blocked serotonin induced coronary flow increasing response, and in the presence of 1 ?M SB269970, serotonin turned into reducing coronary flow. Treatment of TCW295 (8-(2,4-Dimethoxyphenyl)-6-methoxy-2-phenethyl-1,2,3,4-tetrahydroisoquinolin-7-ol hydrochloride), a novel serotonin 5-HT?A/? receptor antagonist, inhibited both serotonin induced coronary flow increasing and decreasing effects. In conclusion, we found serotonin increases coronary flow of isolated rat heart by activating serotonin 5-HT? receptor activation, and this effect can be, at least partially, resistant to L-NAME. PMID:25196212

Chang Chien, Ching-Chia; Hsin, Ling-Wei; Su, Ming-Jai

2015-02-01

386

Active flow control for maximizing performance of spark ignited stratified charge engines. Final report  

SciTech Connect

Reducing the cycle-to-cycle variability present in stratified-charge engines is an important step in the process of increasing their efficiency. As a result of this cycle-to-cycle variability, fuel injection systems are calibrated to inject more fuel than necessary, in an attempt to ensure that the engines fire on every cycle. When the cycle-to-cycle variability is lowered, the variation of work per cycle is reduced and the lean operating limit decreases, resulting in increased fuel economy. In this study an active flow control device is used to excite the intake flow of an engine at various frequencies. The goal of this excitation is to control the way in which vortices shed off of the intake valve, thus lowering the cycle-to-cycle variability in the flow field. This method of controlling flow is investigated through the use of three engines. The results of this study show that the active flow control device did help to lower the cycle-to-cycle variability of the in-cylinder flow field; however, the reduction did not translate directly into improved engine performance.

Fedewa, Andrew; Stuecken, Tom; Timm, Edward; Schock, Harold J.; Shih, Tom-I.P.; Koochesfahani, Manooch; Brereton, Giles

2002-10-15

387

Atmospheric Moisture Transports from Ocean to Land and Global Energy Flows in Reanalyses  

E-print Network

Atmospheric Moisture Transports from Ocean to Land and Global Energy Flows in Reanalyses KEVIN E energy and hydrological cycles from eight current atmospheric reanalyses and their depiction of changes over time. A brief evaluation of the water and energy cycles in the latest version of the NCAR climate

Fasullo, John

388

National Alliance of Clean Energy Incubator Activities - Final Technical Report  

SciTech Connect

Summary of activity related to development of the Alliance of Clean Energy Business Incubators and incubation services provided to the clean energy sector by the Advanced Technology Development Center at the Georgia Institute of Technology.

Chris Downing, P.E.

2004-12-14

389

A Green's Function Approach to PIV Pressure Estimates with an Application to Micro Energy Harvesters in Turbulent and Vortical Flows  

NASA Astrophysics Data System (ADS)

In the present work we demonstrate the feasibility to harness energy from fluid flows by using piezoelectric generators. These ac-coupled devices convert fluid kinetic energy, which otherwise would be wasted, into electrical energy. The available power density in a flowing fluid is proportional to the cube of its velocity and if it is properly harvested can be used for continuously powering very small electronic devices or can be rectified and stored for intermittent use. A key quantity in these applications which affects the performance is the forcing which the fluid exerts on the harvesters. An analytical solution is presented for the Pressure Poisson Equation (PPE) that uses Particle Image Velocimetry (PIV) field data to find the pressure in a flow domain and to calculate the pressure and therefore the force exerted by the fluid on the solid surface. The solution provides a favorable method of calculating pressure field from PIV data as it eliminates the need to compute higher order derivatives of velocity on the domain that are present in viscous terms as well as eliminates the need to integrate Navier-Stokes equations to find the pressure along the boundaries of interest. The solution is validated against a theoretical solution for a pressure distribution inside a tornado-like vortex; pressure solutions obtained by derivative momentum transform method for a vortex flow and some experimental results for the pressure distribution inside a turbulent boundary layer. Several experiments were carried out in which pressure was calculated using PPE: i) a discrete vortex passing over a simple cantilever beam harvester ii) a simple cantilever harvester placed in the boundary layer iii) a self-excited harvester placed in the free stream flow. In a discrete vortex experiment, the self-propelled vortex is passed over the cantilever beam. The pressure distribution and the net force of the beam are calculated by solving PPE as the vortex passes over the beam. In a boundary layer flow, PPE solution was used to estimate pressure fluctuations that are present in the turbulent boundary layer. A simple cantilever harvester is then placed inside the boundary layer. The beam is placed inside the boundary layer at various distances from the wall (y/delta~0-1.5) and at various orientations with respect to the free stream flow angle of attack beta=0o°- -- 180°) for free stream flows 2--11 m/s. Power maps are presented showing the power harvested for various heights and orientations of the harvester. In a self-excited harvester experiment, a harvester with a cylindrical tip mass attached is placed in a uniform cross flow. The PPE solution is used to estimate the strength of pressure inside vortices that are shed off the cylinder forcing it into oscillation. In another experiment to characterize the performance of harvesters inside turbulent flows several simple-cantilever harvesters were placed downstream of passive, semi-passive or an active grid. Passive grid consists of square rods spanning the width and the height of the wind tunnel, semi passive grid is similar to passive but has threaded balls attached to the grid in order to increase turbulence intensity. Active grid has flaps attached to the rods that actively control the closing and opening of sections of the flow thus dramatically increasing turbulence intensity. It is shown that as long as the motion of the harvester actuator does not affect the flow field locally, the power produced to the harvester is proportional to the turbulent kinetic energy of the flow locally.

Goushcha, Oleg

390

Optimizition design of all-vanadium redox flow battery energy storage system  

Microsoft Academic Search

The redox active substance of all-vanadium redox flow battery (VRB) is stored in two separate tanks. In the pumped circulation, the solution flows through the battery, oxidation-reduction reaction takes place on the electrode in both sides of the ion exchange membrane. Compared with other kinds of secondary batteries, VRB has its own characteristics. The arrangement and design of VRB are

Zhang Xueqing; Wei Yi; Xu Shenchu; Zhang Yu

2010-01-01

391

Energy Conservation Activities for Elementary Grades (Or: How To Help Slim Down the Energy Monster). Iowa Developed Energy Activities Sampler, Primary K-2. Revised.  

ERIC Educational Resources Information Center

The revised Iowa Developed Energy Activity Sampler (IDEAS) was compiled using the original IDEAS program and the Energy Conservation Activity Packets (ECAPS). This booklet provides activities for teachers to use in the primary elementary grades (K-2). The activities are organized into nine units, with units 1 through 8 containing three activities…

Iowa State Dept. of Education, Des Moines.

392

Energy-Efficient Variable-Flow Liquid Cooling in 3D Stacked Architectures  

E-print Network

1 Energy-Efficient Variable-Flow Liquid Cooling in 3D Stacked Architectures Ayse K. Coskun , David-efficient cooling, we propose a novel controller to adjust the liquid flow rate to meet the desired temperature the thermal resistances and makes it difficult to remove the heat using conventional cooling methods. Liquid

Coskun, Ayse

393

Spectral wave flow attenuation within submerged canopies: Implications for wave energy dissipation  

Microsoft Academic Search

Communities of benthic organisms can form very rough surfaces (canopies) on the seafloor. Previous studies have shown that an oscillatory flow induced by monochromatic surface waves will drive more flow inside a canopy than a comparable unidirectional current. This paper builds on these previous studies by investigating how wave energy is attenuated within canopies under spectral wave conditions, or random

Ryan J. Lowe; James L. Falter; Jeffrey R. Koseff; Stephen G. Monismith; Marlin J. Atkinson

2007-01-01

394

A case study of energy, water and soil flow chains in an arid ecosystem  

Microsoft Academic Search

Little attention has been directed to the study of soil flow and the complex relationships among energy water and soil flow in terrestrial ecosystems. Soil plays an important role in arid ecosystems. After water soil is the second key factor in the development of an arid ecosystem since soil is the only part of the system capable of absorbing and

A. Yair; M. Shachak

1982-01-01

395

Calculation of the Energy Loss for Tip Leakage Flow in Turbines  

Microsoft Academic Search

A commercial N-S solver has been employed for simulation and investigation of the unsteady flow field inside the tip clearance of a turbine rotor. The main objective of this paper is to introduce a new method of energy loss calculation for the flow field in tip clearance region of a turbine rotor blade This method can be easily used in

Hassanvand Mohsen; Song-tao WANG; Guo-tai FENG; Zhong-qi WANG

2004-01-01

396

Searching for Large-scale flows around Active Regions with Hinode  

NASA Astrophysics Data System (ADS)

Heliosiemic studies have suggested that active regions are surrounded by large-scale inflows (Haber et al. 2004), and it has recently been hypothesized by Hurlburt and DeRosa (2008,HD) that these are due to the enhanced surface cooling resulting from plage and faculae. We seek confirmation of these results using Hinode observations of Active Regions using a variety of methods to infer inflow velocities from of continuum images and Dopplergrams. These flow patterns are then compared to the HD hypothesis. This work has been supported by NASA through contracts NNM07AA01C and NNG06GD45G. References: Haber, D., Hindman, B., Toomre, J. and Thompson, M. 2004, ÐOrganized Subsurface Flows near Active Regions,î Sol. Phys. 220,371. Hurlburt & DeRosa, 2008 ÐOn the longevity of Active Regions,î Ap.J. Lett., submitted

Hurlburt, N.; Derosa, M.; Hagenaar, M.

2008-05-01

397

Investigation of several passive and active methods for turbulent flow separation control  

NASA Technical Reports Server (NTRS)

Relative performance of several passive and active methods for controlling two-dimensional turbulent separated flow associated with a curved backward-facing ramp were investigated at low speeds. Surface static pressure measurement and oil flow visualization results indicate that submerged vortex generators, vortex generator jets, elongated arches at +-alpha, and large-eddy breakup devices at +-alpha placed near the baseline separation location reduce flow separation and increase pressure recovery. Spanwise cylinders reduce flow separation but decrease pressure recovery downstream. Arches with alpha = 0 deg, Helmholtz resonators, and Viets' fluidic flappers examined so far have no significant effect in reducing separation. Wall cooling computation indicates that separation delay on a partially cooled ramp is nearly the same as on a fully-cooled ramp while minimizing the frictional drag increase associated with the wall cooling process.

Lin, J. C.; Howard, F. G.; Bushnell, D. M.; Selby, G. V.

1990-01-01

398

Energy and material flow models for the US steel industry  

Microsoft Academic Search

We develop calibrated models of energy and material consumption patterns in the US steel industry, starting with an energy end-use model based on 1994 Manufacturing Energy Consumption Survey (MECS) data. Then process-step models of material and energy use are developed and calibrated against the energy end-use model and data from the US Commerce Department and the American Iron and Steel

Jan Peter Andersen; Barry Hyman

2001-01-01

399

Food Utilization (Energy-Flow) Investigations with Pieris Brassicae (Large White) Caterpillars.  

ERIC Educational Resources Information Center

Background information, procedures used, and typical results obtained are provided for experiments in which caterpillars are used to investigate energy-flow relationships. Areas in which the experiments could be used include ecology, applied biology, and animal feeding. (DH)

Jones, Derek H. T.

1985-01-01

400

Global energy conversion rate from geostrophic flows into internal lee waves in the deep ocean  

E-print Network

A global estimate of the energy conversion rate from geostrophic flows into internal lee waves in the ocean is presented. The estimate is based on a linear theory applied to bottom topography at O(1–10) km scales obtained ...

Nikurashin, Maxim

401

Energy-Saving Design for Pressure Difference Control in Variable Flow Air Conditioning Systems  

E-print Network

This paper analyzes energy-saving design for pressure-difference control in a variable flow air conditioning system, including the application of a pressure-difference control valve and the installation position of a pressure-difference transducer...

Chen, Y.; Zhang, Z.

2006-01-01

402

Effect of intranasal histamine on nasal mucosal blood flow and the antidiuretic activity of desmopressin.  

PubMed Central

The effects of exogenous histamine on nasal mucosal blood flow and the systemic activity of intranasally administered desmopressin, a vasopressin analogue, were studied in normal volunteers. Ten subjects received either saline or histamine (1, 20, 100, and 500 micrograms) by intranasal spray. Maximal nasal mucosal blood flow response, determined by laser doppler velocimetry, demonstrated a significant (P less than 0.05) linear relationship to histamine dose. Eight additional subjects received each of the following intranasal treatments: 20 micrograms histamine followed by 10 micrograms desmopressin; normal saline followed by 10 micrograms desmopressin; 20 micrograms histamine followed by vehicle; or normal saline and vehicle. Nasal blood flow was determined before and after each treatment. Desmopressin activity was assessed by measuring urine osmolality, flow rate, electrolyte, and creatinine concentration for 24 h after each treatment. The effect of histamine and desmopressin was greater than desmopressin alone, with respect to nasal blood flow response (103 +/- 24 vs. 4 +/- 17%, mean +/- SEM, P less than 0.02), initial urine osmolality (520 +/- 123 vs. 333 +/- 75 mosM, P less than 0.03), urine electrolyte (potassium, 45 +/- 11 vs. 28 +/- 7 meq/liter; sodium, 68 +/- 21 vs. 36 +/- 8 meq/liter, P less than 0.03) and creatinine concentrations (95 +/- 23 vs. 60 +/- 13 mg/dl, P less than 0.03), and the duration of decrease in urine flow rate compared with saline and vehicle. These results suggest that the systemic activity of intranasal desmopressin is enhanced by increasing local nasal blood flow and are consistent with increased transnasal absorption of the peptide. PMID:3624491

Olanoff, L S; Titus, C R; Shea, M S; Gibson, R E; Brooks, C D

1987-01-01

403

System Size, Energy, Pseudorapidity, and Centrality Dependence of Elliptic Flow  

E-print Network

This paper presents measurements of the elliptic flow of charged particles as a function of pseudorapidity and centrality from Cu-Cu collisions at 62.4 and 200 GeV using the PHOBOS detector at the Relativistic Heavy Ion Collider (RHIC). The elliptic flow in Cu-Cu collisions is found to be significant even for the most central events. For comparison with the Au-Au results, it is found that the detailed way in which the collision geometry (eccentricity) is estimated is of critical importance when scaling out system-size effects. A new form of eccentricity, called the participant eccentricity, is introduced which yields a scaled elliptic flow in the Cu-Cu system that has the same relative magnitude and qualitative features as that in the Au-Au system.

B. Alver; for the PHOBOS Collaboration

2006-10-24

404

Modeling of Word Translation: Activation Flow from Concepts to Lexical Items  

ERIC Educational Resources Information Center

Whereas most theoretical and computational models assume a continuous flow of activation from concepts to lexical items in spoken word production, one prominent model assumes that the mapping of concepts onto words happens in a discrete fashion (Bloem & La Heij, 2003). Semantic facilitation of context pictures on word translation has been taken to…

Roelofs, Ardi; Dijkstra, Ton; Gerakaki, Svetlana

2013-01-01

405

Differential response of human basophil activation markers: a multi-parameter flow cytometry approach  

Microsoft Academic Search

BACKGROUND: Basophils are circulating cells involved in hypersensitivity reactions and allergy but many aspects of their activation, including the sensitivity to external triggering factors and the molecular aspects of cell responses, are still to be focused. In this context, polychromatic flow cytometry (PFC) is a proper tool to investigate basophil function, as it allows to distinguish the expression of several

Salvatore Chirumbolo; Antonio Vella; Riccardo Ortolani; Marzia De Gironcoli; Pietro Solero; Giuseppe Tridente; Paolo Bellavite

2008-01-01

406

Implementation of Inverse Neural Control To VSC Converter for Active and Reactive Power Flow  

Microsoft Academic Search

In this paper is presented the implementation of a VSC (voltage source converter), to be used in HVDC (high voltage direct current) systems. The control is carried out of active and reactive power flow for the VSC, by an inverse neural control, based on multi layer perceptron. The non linearity nature presents learning problems in the Neural Network like poor

F. A. Forero R; A. M. Molina M; J. G. Guarnizo M; H. R. Chamorro V

2009-01-01

407

Feedforward control of the external carbon flow rate in an activated sludge process  

Microsoft Academic Search

Biological nitrogen removal in an activated sludge process is obtained by two biological processes: nitrification and denitrification. Denitrifying bacteria need sufficient amounts of readily metabolized carbon. The objective of this paper is to develop an automatic control strategy for adjusting the external carbon flow rate so that the nitrate concentration in the last anoxic compartment is kept at a low

P. Samuelsson; B. Carlsson

2000-01-01

408

Numerical simulation of flows in air treatment devices using activated carbon cloths filters  

Microsoft Academic Search

The determination of pressure drops is of major interest in the design of most air treatment processes, which often use activated carbon granules, beads in packing columns, or carbon cloths, for the removal of volatile organic compounds or odorous molecules charged in the air. In this paper, numerical simulations of flows occurring in air treatment devices are performed using computational

Jean-Noël Baléo

2000-01-01

409

Temperature-Gated Thermal Rectifier for Active Heat Flow Control Kedar Hippalgaonkar,,  

E-print Network

conversion. Like electronic devices developed for the control of electric power, it is very desirableTemperature-Gated Thermal Rectifier for Active Heat Flow Control Jia Zhu,, Kedar Hippalgaonkar, University of California at Berkeley, Berkeley, California 94720, United States § Department of Physics

Wu, Junqiao

410

From data-flow task to multitasking: applying the synchronous approach to active vision in robotics  

Microsoft Academic Search

We apply the synchronous approach to real time active visual three dimensional (3D) reconstruction using a camera mounted on a robot end effector. It illustrates the adequateness of SIGNAL, a synchronous data flow programming language and environment, for the specification of a system dealing with various domains in central theory and computer vision. More precisely, our application consists in the

Eric Marchand; Eric Rutten; F. Chaumette

1997-01-01

411

Aeroelastic Load Control program: in-flight demonstration of active flow control technology  

Microsoft Academic Search

The USAF Test Pilot School (TPS) and the Air Force Research Laboratory (AFRL) have partnered with Lockheed Martin and General Electric (GE) Global Research to execute the first flight test using dual bimorph synthetic jet (DBSJ) actuators in order to demonstrate the effectiveness of active flow control technology. The first phase of the aeroelastic load control (ALC) program demonstrated the

Leonard Shaw; Raniel C. Hidalgo; J. W. Rogers

2006-01-01

412

EFFECTS OF FLOW EQUALIZATION ON THE OPERATION AND PERFORMANCE OF AN ACTIVATED SLUDGE PLANT  

EPA Science Inventory

A plant-scale research program was carried out for more than a year to evaluate the impact of flow equalization on the 14,000 cu m/day (3.7 mgd) upgraded activated sludge plant at Ypsilanti Township, Michigan. Process streams were characterized under both equalized and unequalize...

413

Concentration of Symphytum officinale extracts with cytostatic activity by tangential flow ultrafiltration  

Microsoft Academic Search

Symphytum officinale L (Boraginaceae) species are currently used in the Romanian traditional medicine to treat different human and animal disease, being also active in certain cancer forms. This work's aim consists in obtaining of Symphytum officinale concentrated extracts by using performance membrane processes, aqueous extracts prepared were concentrated by tangential flow ultrafiltration with a Koch Laboratory Cell CF-1 membrane. The

ELENA NEAGU; VERONICA MOROEANU; GABRIEL LUCIAN RADU

2008-01-01

414

The evolution of an active silicic lava flow field: an ETM+ perspective  

E-print Network

'i, 2525 Correa Road, Honolulu, HI 96822, USA b INSIVUMEH, 7a Av. 14-57, Zona 13, Guatemala City, Guatemala, Houghton, MI 49931, USA d Santa Maria Volcano Observatory, c/o INSIVUMEH, 7a Av. 14-57, Zona 13, Guatemala City, Guatemala Accepted 5 December 2003 Abstract An active dacitic lava flow began advancing down

Rose, William I.

415

On active surge control of compressors using a mass flow Bjrnar Bhagen and Jan Tommy Gravdahl  

E-print Network

, the stable operating region of centrifugal compressors is bounded due to the occur- rence of surge. Surge of a centrifugal compressor driven by an electrical motor and the control system consists of three partsOn active surge control of compressors using a mass flow observer Bjørnar Bøhagen and Jan Tommy

Gravdahl, Jan Tommy

416

Transformation from Data Flow Diagram to UML2.0 activity diagram  

Microsoft Academic Search

Model transformations are frequently applied in business process modeling to bridge between languages on a different level of abstraction and formality This paper proposes a model transformation from Data Flow Diagrams (DFD) which have been used widely in structure requirement analysis phase to UML Activity Diagrams (UML-AD) which have been used widely in various phases of Object Oriented Development Method.

Fanchao Meng; Dianhui Chu; Dechen Zhan

2010-01-01

417

The Cooling Rate of an Active Aa Lava Flow Determined Using an Orbital Imaging Spectrometer  

Microsoft Academic Search

The surface temperature of an active lava flow is an important physical property to measure. Through its influence on lava crystallinity, cooling exerts a fundamental control on lava rheology. Remotely sensed thermal radiance data acquired by multispectral sensors such as Landsat Thematic Mapper and the Terra Advanced Spaceborne Thermal Emission and Reflection Radiometer, are of insufficient spectral and radiometric fidelity

Robert Wright; Harold Garbeil

2010-01-01

418

Poly (3,4-ethylendioxithiophene) (PEDOT) oxidation. Activation energy and conformational energy.  

E-print Network

Poly (3,4-ethylendioxithiophene) (PEDOT) oxidation. Activation energy and conformational energy. T.caballero@upct.es Abstract. The oxidation kinetics of films of the conducting polymer PEDOT-ClO4 after electrochemical. Keywords: pedot, oxidation, kinetics, reaction coefficients, activation energy, conformational energy. 1

Otero, Toribio Fernández

419

Estimating activity energy expenditure: how valid are physical activity questionnaires?1-3  

Microsoft Academic Search

Activity energy expenditure (AEE) is the modifiable component of total energy expenditure (TEE) derived from all activities, both volitional and nonvolitional. Because AEE may affect health, there is interest in its estimation in free-living people. Physical activity questionnaires (PAQs) could be a feasible approach to AEE estima- tion in large populations, but it is unclear whether or not any PAQ

Heather K Neilson; Paula J Robson; Christine M Friedenreich; Ilona Csizmadi

420

Effect of flow oscillations on axial energy transport in a porous material  

NASA Technical Reports Server (NTRS)

The effects of flow oscillations on axial energy diffusion in a porous medium, in which the flow is continuously disrupted by the irregularities of the porous structure, are analyzed. The formulation employs an internal heat transfer coefficient that couples the fluid and solid temperatures. The final relationship shows that the axial energy transport per unit cross-sectional area and time is directly proportional to the axial temperature gradient and the square of the maximum fluid displacement.

Siegel, R.

1987-01-01

421

Numerical Modeling on the Performance of Aquifer Thermal Energy Storage System under Cyclic Flow Regime  

Microsoft Academic Search

Coupled hydrogeological-thermal model for simulating the thermal energy storage system in aquifer is described. It is essential to provide an optimized configuration and operation schedule for wells on the site. This paper presents numerical investigations and thermohydraulic evaluation of two-well models of aquifer thermal energy storage (ATES) system operating under cyclic flow regime. A three-dimensional numerical model for groundwater flow

Kun Sang Lee; Sang Jin Jeong

2008-01-01

422

Dissipation of the energy of a high-velocity flow in tunnel spillways  

Microsoft Academic Search

Conclusions  \\u000a1. \\u000aThe investigations led to finding a new method for dissipating the energy in a high-velocity flow in tunnel spillways. The effectiveness of the method at heads on the tunnel gates up to 200 m was established experimentally.\\u000a2. \\u000aIt was established that the maximum effectiveness of dissipating the excess energy of the flow is attained upon interaction of

R. S. Gal'perin; N. N. Rozanova; L. A. Zolotov; G. N. Tsedrov

1979-01-01

423

MAGNETIC ENERGY AND HELICITY IN TWO EMERGING ACTIVE REGIONS IN THE SUN  

SciTech Connect

The magnetic energy and relative magnetic helicity in two emerging solar active regions, AR 11072 and AR 11158, are studied. They are computed by integrating over time the energy and relative helicity fluxes across the photosphere. The fluxes consist of two components: one from photospheric tangential flows that shear and braid field lines (shear term), the other from normal flows that advect magnetic flux into the corona (emergence term). For these active regions: (1) relative magnetic helicity in the active-region corona is mainly contributed by the shear term, (2) helicity fluxes from the emergence and the shear terms have the same sign, (3) magnetic energy in the corona (including both potential energy and free energy) is mainly contributed by the emergence term, and (4) energy fluxes from the emergence term and the shear term evolved consistently in phase during the entire flux emergence course. We also examine the apparent tangential velocity derived by tracking field-line footpoints using a simple tracking method. It is found that this velocity is more consistent with tangential plasma velocity than with the flux transport velocity, which agrees with the conclusion by Schuck.

Liu, Y. [W. W. Hansen Experimental Physics Laboratory, Stanford University, Stanford, CA 94305-4085 (United States); Schuck, P. W. [Space Weather Laboratory, Code 674, Heliophysics Science Division, NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States)

2012-12-20

424

Magnetic Energy and Helicity in Two Emerging Active Regions in the Sun  

NASA Technical Reports Server (NTRS)

The magnetic energy and relative magnetic helicity in two emerging solar active regions, AR 11072 and AR 11158,are studied. They are computed by integrating over time the energy and relative helicity fluxes across the photosphere. The fluxes consist of two components: one from photospheric tangential flows that shear and braid field lines (shear term), the other from normal flows that advect magnetic flux into the corona (emergence term). For these active regions: (1) relative magnetic helicity in the active-region corona is mainly contributed by the shear term,(2) helicity fluxes from the emergence and the shear terms have the same sign, (3) magnetic energy in the corona (including both potential energy and free energy) is mainly contributed by the emergence term, and(4) energy fluxes from the emergence term and the shear term evolved consistently in phase during the entire flux emergence course.We also examine the apparent tangential velocity derived by tracking field-line footpoints using a simple tracking method. It is found that this velocity is more consistent with tangential plasma velocity than with the flux transport velocity, which agrees with the conclusion by Schuck.

Liu, Y.; Schuck, P. W.

2012-01-01

425

The capacity of a freeway segment should be measured only when it is an active bottleneck. The properties of flows at active freeway bottle-  

E-print Network

. The properties of flows at active freeway bottle- necks have a bearing on both the definition of capacity downstream. Therefore, capacity should be measured only at, or immediately downstream of, active bottle

Levinson, David M.

426

ANTI-PARALLEL EUV FLOWS OBSERVED ALONG ACTIVE REGION FILAMENT THREADS WITH HI-C  

SciTech Connect

Plasma flows within prominences/filaments have been observed for many years and hold valuable clues concerning the mass and energy balance within these structures. Previous observations of these flows primarily come from H? and cool extreme-ultraviolet (EUV) lines (e.g., 304 Å) where estimates of the size of the prominence threads has been limited by the resolution of the available instrumentation. Evidence of 'counter-steaming' flows has previously been inferred from these cool plasma observations, but now, for the first time, these flows have been directly imaged along fundamental filament threads within the million degree corona (at 193 Å). In this work, we present observations of an AR filament observed with the High-resolution Coronal Imager (Hi-C) that exhibits anti-parallel flows along adjacent filament threads. Complementary data from the Solar Dynamics Observatory (SDO)/Atmospheric Imaging Assembly (AIA) and Helioseismic and Magnetic Imager are presented. The ultra-high spatial and temporal resolution of Hi-C allow the anti-parallel flow velocities to be measured (70-80 km s{sup –1}) and gives an indication of the resolvable thickness of the individual strands (0.''8 ± 0.''1). The temperature of the plasma flows was estimated to be log T (K) = 5.45 ± 0.10 using Emission Measure loci analysis. We find that SDO/AIA cannot clearly observe these anti-parallel flows or measure their velocity or thread width due to its larger pixel size. We suggest that anti-parallel/counter-streaming flows are likely commonplace within all filaments and are currently not observed in EUV due to current instrument spatial resolution.

Alexander, Caroline E.; Walsh, Robert W.; Régnier, Stéphane [Jeremiah Horrocks Institute, University of Central Lancashire, Preston PR1 2HE (United Kingdom)] [Jeremiah Horrocks Institute, University of Central Lancashire, Preston PR1 2HE (United Kingdom); Cirtain, Jonathan; Winebarger, Amy R. [NASA Marshall Space Flight Center, VP 62, Huntsville, AL 35812 (United States)] [NASA Marshall Space Flight Center, VP 62, Huntsville, AL 35812 (United States); Golub, Leon; Korreck, Kelly; Weber, Mark [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States)] [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Kobayashi, Ken [Center for Space Plasma and Aeronomic Research, The University of Alabama in Huntsville, 320 Sparkman Drive, Huntsville, AL 35805 (United States)] [Center for Space Plasma and Aeronomic Research, The University of Alabama in Huntsville, 320 Sparkman Drive, Huntsville, AL 35805 (United States); Platt, Simon; Mitchell, Nick [School of Computing, Engineering and Physical Sciences, University of Central Lancashire, Preston PR1 2HE (United Kingdom)] [School of Computing, Engineering and Physical Sciences, University of Central Lancashire, Preston PR1 2HE (United Kingdom); DePontieu, Bart; Title, Alan [Lockheed Martin Solar and Astrophysics Lab, 3251 Hanover Street, Org. ADBS, Bldg. 252, Palo Alto, CA (United States)] [Lockheed Martin Solar and Astrophysics Lab, 3251 Hanover Street, Org. ADBS, Bldg. 252, Palo Alto, CA (United States); DeForest, Craig [Southwest Research Institute, 1050 Walnut Street, Suite 300, Boulder, CO 80302 (United States)] [Southwest Research Institute, 1050 Walnut Street, Suite 300, Boulder, CO 80302 (United States); Kuzin, Sergey [P.N. Lebedev Physical institute of the Russian Academy of Sciences, Leninskii prospekt, 53, 119991 Moscow (Russian Federation)] [P.N. Lebedev Physical institute of the Russian Academy of Sciences, Leninskii prospekt, 53, 119991 Moscow (Russian Federation)

2013-09-20

427

Fine powder flow under humid environmental conditions from the perspective of surface energy.  

PubMed

The influence of humidity on surface energetics and flow behavior of fine pharmaceutical powders was investigated. Amorphous and crystalline fine powders with hydrophilic (Corn starch and Avicel PH105) and hydrophobic (ibuprofen) nature were considered for this study. The surface energy was determined using surface energy analyzer and flow behavior was measured in terms of unconfined yield stress (UYS) using a shear tester. The study showed that unlike hydrophobic ibuprofen powder, surface energy and flow of hydrophilic excipient powders were affected by relative humidity (RH). The Lifshitz-van der Waals dispersive (?(LW)) component of surface energy barely changed with varying RH for all pharmaceutical powders. For hydrophilic excipients, the specific component of surface energy (?(SP)) was found to increase with increasing RH. Furthermore, for these excipients, flow deterioration at elevated RH was observed due to increased capillary bridge formation. Detailed analysis showed that ?(SP) component of surface energy can be an effective indicator for flow behavior of fine powders under varying humid conditions. The present study also brought out the existence of different regimes of probable interparticle forces which dictate the bulk flow behavior of fine hydrophilic powder under humid conditions. PMID:25772418

Karde, Vikram; Ghoroi, Chinmay

2015-05-15

428

Heat flow, depth-temperature variations and stored thermal energy for enhanced geothermal systems in Canada  

NASA Astrophysics Data System (ADS)

In order to help assessment of enhanced geothermal energy potential in Canada, we constructed a new series of heatflow and depth-temperature distribution maps (down to 10 km). We focus on high-temperature resources (>150 °C) capable of electrical production. Maps presented show large temperature variability, related mainly to heat flow patterns. The highest temperatures occur in western and northern Canada. Here temperatures greater than 150 °C, required for enhanced geothermal systems (EGS), can be reached at reasonable drilling depths of <5 km. Heat flow, by itself however, is not a sufficient tool to predict areas of high energy content. A combination of thick low thermal conductivity sedimentary blankets and moderate to high heat flow areas can generate targets that are as favorable as regions with high conductivity and high heat flow. Some moderate heat flow areas in the deeper parts of the Western Canada Sedimentary Basin have heat content comparable to high heat flow zones of the the Canadian Cordillera. The magnitude of in-place thermal energy available for future heat 'mining/farming' was esitmated throughout Canada by calculating heat released through cooling a defined rock volume through a fixed temperature change. These estimates show the first-order appoximation of available geothermal heat content. The fraction of true heat energy available will be as low as 0.02 of these values. However, even this more limited energy production could be large enough to be a considerable future renewable energy resource for Canada.

Majorowicz, Jacek; Grasby, Stephen E.

2010-09-01

429

Simple Activity Demonstrates Wind Energy Principles  

ERIC Educational Resources Information Center

Wind energy is an exciting and clean energy option often described as the fastest-growing energy system on the planet. With some simple materials, teachers can easily demonstrate its key principles in their classroom. (Contains 1 figure and 2 tables.)

Roman, Harry T.

2012-01-01

430

Energy and materials flows in the iron and steel industry  

Microsoft Academic Search

Past energy-consumption trends and future energy-conservation opportunities are investigated for the nation's iron and steel industry. It is estimated that, in 1980, the industry directly consumed approximately 2.46 x 10¹⁵ Btu of energy (roughly 3% of total US energy consumption) to produce 111 million tons of raw steel and to ship 84 million tons of steel products. Direct plus indirect

1983-01-01

431

1 Managed by UT-Battelle for the U.S. Department of Energy PASI_2012_Flowing_Target_Challenges  

E-print Network

1 Managed by UT-Battelle for the U.S. Department of Energy PASI_2012_Flowing_Target_Challenges, stress / shock #12;2 Managed by UT-Battelle for the U.S. Department of Energy PASI_2012_Flowing_Target_Challenges;3 Managed by UT-Battelle for the U.S. Department of Energy PASI_2012_Flowing_Target_Challenges Flowing

McDonald, Kirk

432

Energy flow in high speed perforation and cutting  

SciTech Connect

It is demonstrated that effects of long rod penetrators on targets can be modeled by introducing a high pressure (energy) column on the penetration path in place of the projectile. This energy can be obtained from the kinetic energy of the penetrator; the equations of state of the materials used and a Bernoulli penetration condition. The model is supported by detailed hydro calculations.

van Thiel, M.

1980-10-07

433

Development of a redox flow (RF) battery for energy storage  

Microsoft Academic Search

The Kansai Electric Power Company has been engaged in the ongoing development of the redox flow battery (RFB) since 1985 in collaboration with Sumitomo Electric Industries, Ltd. The fundamentals and performance of RFB have been verified through field test projects such as the prototype 450 kW 2 h system and the advanced design 168 kW 8 h system installed in

N. Tokuda; M. Furuya; Y. Kikuoko; Y. Tsutui; T. Kumamoto; T. Kanno

2002-01-01

434

Flow depth and energy coefficient relatiohnships for stepped spillways  

Technology Transfer Automated Retrieval System (TEKTRAN)

A multi-year, large-scale physical model study of stepped chutes was conducted over a broad range of design parameters (i.e. step heights, slopes, and unit discharges). Air entrainment developed naturally as the flow descended the chute. Air entrainment began to develop downstream of the surface i...

435

Persistent energy flow for a stochastic wave equation model in nonequilibrium statistical mechanics  

E-print Network

We consider a one-dimensional partial differential equation system modeling heat flow around a ring. The system includes a Klein-Gordon wave equation for a field satisfying spatial periodic boundary conditions, as well as Ornstein-Uhlenbeck stochastic differential equations with finite rank dissipation and stochastic driving terms modeling heat baths. There is an energy flow around the ring. In the case of a linear field with different (fixed) bath temperatures, the energy flow can persist even when the interaction with the baths is turned off. A simple example is given.

Lawrence E. Thomas

2012-04-29

436

Centrality dependence of multiplicity, transverse energy, and elliptic flow from hydrodynamics  

SciTech Connect

The centrality dependence of the charged multiplicity, transverse energy, and elliptic flow coefficient is studied in a hydrodynamic model, using a variety of different initializations which model the initial energy or entropy production process as a hard or soft process, respectively. While the charged multiplicity depends strongly on the chosen initialization, the p{sub T}-integrated elliptic flow for charged particles as a function of charged particle multiplicity and the p{sub T}-differential elliptic flow for charged particles in minimum bias events turn out to be almost independent of the initialization.

Kolb, Peter F.; Heinz, Ulrich; Huovinen, Pasi; Eskola, Kari J.; Tuominen, Kimmo

2001-03-21

437

Lift and Drag on a NACA0015 Airfoil With Duty Cycle Active Flow Control  

NASA Astrophysics Data System (ADS)

Active flow control experiments were carried out over a NACA 0015 airfoil with a trailing edge flap. Two arrays of synthetic jet actuators were mounted in the airfoil with one on near the leading edge (0.1c) and the other on the main wing body near the wing/flap interface (0.65c). Characterization of the SJA's showed they produced their highest exit velocities at a frequency of 1100 Hz, which was near the natural frequency of the piezo membranes. When actuated at frequencies corresponding to the flow natural frequencies (10-100Hz) the jets produced no jet velocity. In order to control the flow using a frequency near the flow's natural shedding frequency the synthetic jets were actuated using a forcing frequency near the piezo natural frequency with a duty cycle frequency of 10-1000Hz. Force balance results showed that for a 0 flap deflection the active flow control delayed stall and lowered drag regardless of the duty cycle frequency. At flap deflections of 20 and 40 differences were observed between the continuously forced and duty cycles cases. For these cases continuous forcing increased the stall angle and reduced drag. Duty cycle forcing also delayed stall however it significantly increased drag near the stall AOA even compared to the no forcing case.

Kabiri, Pooya; Bohl, Douglas; Ahmadi, Goodarz

2011-11-01

438

Biomass I. Science Activities in Energy [and] Teacher's Guide.  

ERIC Educational Resources Information Center

Designed for science students in fourth, fifth, and sixth grades, the activities in this unit illustrate principles and problems related to biomass as a form of energy. (The word biomass is used to describe all solid material of animal or vegetable origin from which energy may be extracted.) Twelve student activities using art, economics,…

Oak Ridge Associated Universities, TN.

439

Active and reactive power in stochastic resonance for energy harvesting  

E-print Network

A power allocation to active and reactive power in stochastic resonance is discussed for energy harvesting from mechanical noise. It is confirmed that active power can be increased at stochastic resonance, in the same way of the relationship between energy and phase at an appropriate setting in resonance.

Kubota, Madoka; Hikihara, Takashi

2015-01-01

440

Local expansion flows of galaxies: quantifying acceleration effect of dark energy  

NASA Astrophysics Data System (ADS)

The nearest expansion flow of galaxies observed around the Local group is studied as an archetypical example of the newly discovered local expansion flows around groups and clusters of galaxies in the nearby Universe. The flow is accelerating due to the antigravity produced by the universal dark energy background. We introduce a new acceleration measure of the flow which is the dimensionless ``acceleration parameter" Q (x) = x - x-2 depending on the normalized distance x only. The parameter is zero at the zero-gravity distance x = 1, and Q(x) ? x, when x ? 1. At the distance x = 3, the parameter Q = 2.9. Since the expansion flows have a self-similar structure in normalized variables, we expect that the result is valid as well for all the other expansion flows around groups and clusters of galaxies on the spatial scales from ˜ 1 to ˜ 10 Mpc everywhere in the Universe.

Chernin, A. D.; Teerikorpi, P.

2013-08-01

441

Steady shocks around black holes produced by sub-keplerian flows with negative energy  

E-print Network

We discuss a special case of formation of axisymmetric shocks in the accretion flow of ideal gas onto a Schwarzschild black hole: when the total energy of the flow is negative. The result of our analysis enlarges the parameter space for which these steady shocks are exhibited in the accretion of gas rotating around relativistic stellar objects. Since keplerian disks have negative total energy, we guess that, in this energy range, the production of the shock phenomenon might be easier than in the case of positive energy. So our outcome reinforces the view that sub-keplerian flows of matter may significantly affect the physics of the high energy radiation emission from black hole candidates. We give a simple procedure to obtain analytically the position of the shocks. The comparison of the analytical results with the data of 1D and 2D axisymmetric numerical simulations confirms that the shocks form and are stable.

D. Molteni; G. Gerardi; V. Teresi

2005-11-10

442

Steady shocks around black holes produced by sub-keplerian flows with negative energy  

E-print Network

We discuss a special case of formation of axisymmetric shocks in the accretion flow of ideal gas onto a Schwarzschild black hole: when the total energy of the flow is negative. The result of our analysis enlarges the parameter space for which these steady shocks are exhibited in the accretion of gas rotating around relativistic stellar objects. Since keplerian disks have negative total energy, we guess that, in this energy range, the production of the shock phenomenon might be easier than in the case of positive energy. So our outcome reinforces the view that sub-keplerian flows of matter may significantly affect the physics of the high energy radiation emission from black hole candidates. We give a simple procedure to obtain analytically the position of the shocks. The comparison of the analytical results with the data of 1D and 2D axisymmetric numerical simulations confirms that the shocks form and are stable.

Molteni, D; Teresi, V

2006-01-01

443

Variational energy principle for compressible, baroclinic flow. 1: First and second variations of total kinetic action  

NASA Technical Reports Server (NTRS)

The case of a cold gas in the absence of external force fields is considered. Since the only energy involved is kinetic energy, the total kinetic action (i.e., the space-time integral of the kinetic energy density) should serve as the total free-energy functional in this case, and as such should be a local minimum for all possible fluctuations about stable flow. This conjecture is tested by calculating explicit, manifestly covariant expressions for the first and second variations of the total kinetic action in the context of Lagrangian kinematics. The general question of the correlation between physical stability and the convexity of any action integral that can be interpreted as the total free-energy functional of the flow is discussed and illustrated for the cases of rectillinear and rotating shearing flows.

Schmid, L. A.

1977-01-01

444

Energy Conservation Activities for Elementary Grades (Or: How to Help Slim Down the Energy Monster). Iowa Developed Energy Activities Sampler, Intermediate 3-5.  

ERIC Educational Resources Information Center

The revised Iowa Developed Energy Activity Sampler (IDEAS) was compiled using the original IDEAS program and the Energy Conservation Activity Packets (ECAPS). This booklet provides activities for teachers in the intermediate elementary grades (3-5) and is designed to enable students to develop a comprehensive understanding of energy concepts. Each…

Iowa State Dept. of Education, Des Moines. Div. of Instructional Services.

445

Energy Conservation Activities for Elementary Grades (Or: How To Help Slim Down the Energy Monster). Iowa Developed Energy Activities Sampler, Intermediate 3-5. Revised.  

ERIC Educational Resources Information Center

The revised Iowa Developed Energy Activity Sampler (IDEAS) was compiled using the original IDEAS program and the Energy Conservation Activity Packets (ECAPS). This booklet provides activities for teachers in the intermediate elementary grades (3-5) and is designed to enable students to develop a comprehensive understanding of energy concepts. Each…

Iowa State Dept. of Education, Des Moines.

446

Signal averaged laser Doppler measurements of activation-flow coupling in the rat forepaw somatosensory cortex.  

PubMed

Regional alterations in cerebral blood flow (CBF) are widely used as a surrogate for neuronal function based on an intact coupling between changes in regional CBF and metabolism, activation-flow coupling (AFC). To further investigate parameters affecting AFC, we have implemented a rat model with electrical forepaw stimulation under alpha-chloralose anesthesia using laser Doppler (LD) measurements of flow parameters through thinned skull over contralateral somatosensory cortex. Signal averaging of the LD response was used to improve reproducibility. A characteristic flow response to electrical forepaw stimulation was reliably recorded from the somatosensory cortex using signal averaging. Stimulation at 5 Hz maximized the LD response, and constant current stimulation up to 1 mA did not induce changes in systemic blood pressure. The shape of the flow response consisted of an initial peak followed by a steady state plateau phase which was observed for stimulation durations longer than 4 s. When individual LD parameters of velocity, red blood cell concentration (CRBC), and cerebral blood flow (CBF) were compared, changes in LDCBF were primarily attributable to changes in LDvelocity rather than LDCRBC. This finding was also observed during hypercapnia. Characterization of AFC in the model provides a background for future studies of the effects of pharmacological manipulation or pathophysiological states. PMID:9689458

Detre, J A; Ances, B M; Takahashi, K; Greenberg, J H

1998-06-15

447

Active Control of Flow Separation and Structural Vibrations of a Wind Turbine Blade  

NASA Astrophysics Data System (ADS)

The feasibility of using arrays of synthetic jet actuators to control flow separation and blade vibrations of a wind turbine blade (S809 airfoil) model was explored in wind tunnel experiments. Using this technique, the global flow field over the finite span blade was altered such that at high angles of attack flow separation was mitigated. This resulted in a significant decrease in the vibration of the blade. In addition, flow control was implemented at low angles of attack using a spanwise distribution of active Gurney flaps, instrumented with synthetic jet actuators. The moments and forces on the blade were measured using a six component wall-mounted load cell. In addition, PIV technique was used to quantify the flow field over the blade. The structural vibrations were quantified using strain gauges, placed near the blade's root, and accelerometers, located near the blade's tip. Using synthetic jets, the flow over the blade was either fully or partially reattached, depending on the angle of attack, the spanwise location along the blade, and the Reynolds number. This resulted in a significant reduction in blade's vibrations, where the amplitude of the tip deflection was found to be proportionally controllable by either changing the momentum coefficient, the number of synthetic jets used, or their driving waveform.

Maldonado, Victor; Amitay, Michael; Gressick, William

2008-11-01

448

Numerical Modeling and Simulations on Electo-Active Polymer Flow Control  

NASA Astrophysics Data System (ADS)

The primary focus of this study is to identify the effects of vibrating Electro-Active Polymer (EAP) flow control on the flow field, specifically within the boundary layer. The EAPs represent a light-weight and adaptable flow control solution for micro-air vehicles (MAV). In this study, the interaction of the flow field over a flat plate and NACA 0009 airfoil are modeled at a Reynolds number of 20,000 using an Arbitrary Lagrangian Eulerian finite element formulation. In the simulations, the EAP vibration is prescribed based on the measurements from the experiments. The results show the EAPs do alter the boundary layer flow field and the size of the separation bubble. Three different diameter EAPs are examined on the flat plate model: 6mm, 9mm, and 12mm. Each is evaluated at different vibrational frequencies and maximum amplitudes. The performance of the EAPs on the NACA 0009 model are also evaluated while the airfoil is experiencing a pitching motion and gusts. Both instantaneous and time averaged flow fields are analyzed. The results from the numerical simulations are compared to baseline CFD simulations and wind tunnel results.

Weddle, Andrew; Amitay, Michael; Zhang, Lucy

2011-11-01

449

Solar Energy Education. Renewable energy activities for chemistry and physics  

SciTech Connect

Information on renewable energy sources is provided for students in this teachers' guide. With the chemistry and physics student in mind, solar energy topics such as absorber plate coatings for solar collectors and energy collection and storage methods are studied. (BCS)

Not Available

1985-01-01

450

F-actin polymerization and retrograde flow drive sustained PLC?1 signaling during T cell activation.  

PubMed

Activation of T cells by antigen-presenting cells involves assembly of signaling molecules into dynamic microclusters (MCs) within a specialized membrane domain termed the immunological synapse (IS). Actin and myosin IIA localize to the IS, and depletion of F-actin abrogates MC movement and T cell activation. However, the mechanisms that coordinate actomyosin dynamics and T cell receptor signaling are poorly understood. Using pharmacological inhibitors that perturb individual aspects of actomyosin dynamics without disassembling the network, we demonstrate that F-actin polymerization is the primary driver of actin retrograde flow, whereas myosin IIA promotes long-term integrity of the IS. Disruption of F-actin retrograde flow, but not myosin IIA contraction, arrested MC centralization and inhibited sustained Ca(2+) signaling at the level of endoplasmic reticulum store release. Furthermore, perturbation of retrograde flow inhibited PLC?1 phosphorylation within MCs but left Zap70 activity intact. These studies highlight the importance of ongoing actin polymerization as a central driver of actomyosin retrograde flow, MC centralization, and sustained Ca(2+) signaling. PMID:22665519

Babich, Alexander; Li, Shuixing; O'Connor, Roddy S; Milone, Michael C; Freedman, Bruce D; Burkhardt, Janis K

2012-06-11

451

F-actin polymerization and retrograde flow drive sustained PLC?1 signaling during T cell activation  

PubMed Central

Activation of T cells by antigen-presenting cells involves assembly of signaling molecules into dynamic microclusters (MCs) within a specialized membrane domain termed the immunological synapse (IS). Actin and myosin IIA localize to the IS, and depletion of F-actin abrogates MC movement and T cell activation. However, the mechanisms that coordinate actomyosin dynamics and T cell receptor signaling are poorly understood. Using pharmacological inhibitors that perturb individual aspects of actomyosin dynamics without disassembling the network, we demonstrate that F-actin polymerization is the primary driver of actin retrograde flow, whereas myosin IIA promotes long-term integrity of the IS. Disruption of F-actin retrograde flow, but not myosin IIA contraction, arrested MC centralization and inhibited sustained Ca2+ signaling at the level of endoplasmic reticulum store release. Furthermore, perturbation of retrograde flow inhibited PLC?1 phosphorylation within MCs but left Zap70 activity intact. These studies highlight the importance of ongoing actin polymerization as a central driver of actomyosin retrograde flow, MC centralization, and sustained Ca2+ signaling. PMID:22665519

Babich, Alexander; Li, Shuixing; O'Connor, Roddy S.; Milone, Michael C.; Freedman, Bruce D.

2012-01-01

452

Reduction of vortex shedding intensity from a cylinder using semi-active flow control  

NASA Astrophysics Data System (ADS)

Experiments were performed in the open water channel at the Waterpower Laboratory, NTNU, Norway, with the aim of reducing vortex shedding intensity by semi-active flow control. The test rig consisted of a perforated steel tube lined by a rubber bellows. The holes (d/D=0.6) formed a line at the leading edge, one tube diameter apart. Two flow control modes were attainable; (1) lining being flush with the cylinder wall, and (2) pressurized lining creating leading edge bumps. Upstream flow conditions were monitored, and used as input for the control loop governing the pressure of the lining. A flat metal rod, onto which strain gauges were glued, was positioned in the wake. It was assumed that the motion of the rod corresponded to the velocity components normal to the main flow direction. Thus the motion of the rod described the vortex shedding from the tube. Strouhal numbers were found to be approximately 0.3. It was the assumption that the bumps would disrupt vortex formation and reduce the vortex intensity. Tests showed that the assumption was plausible, with observed intensity reductions of 15-30% for ReD ˜ [20000 to 50000]. Plots also appear to show a breakdown of organization in the wake when the tube is in activated mode. It was shown that semi-active control of vortex shedding behind a cylinder is achievable.

Ekanger, Jarle V.; Kjeldsen, Morten

2011-11-01

453

Viscosity B-coefficients and activation parameters for viscous flow of a solution of heptanedioic acid in aqueous sucrose solution.  

PubMed

Viscosity and density data for the system of heptanedioic acid dissolved in aqueous sucrose solution at temperature range from 288.15 to 313.15 K have been measured. The viscosity B-coefficients for heptanedioic acid in aqueous sucrose solution has been calculated. The effect of temperature and sucrose concentration on the B-coefficients is discussed. On the basis of the Feakins equation, the activation parameters (Deltamu3++, DeltaH3++, DeltaS3++, DeltaG12(0)++, DeltaH12(0)++ and DeltaS12(0)++) for viscous flow of the solution have been evaluated, together with the Gibbs energy of transfer for the solute from the ground state solvent to the hypothetical viscous transition state solvent (DeltaG3++(1-1')). The effect of sucrose concentration and temperature on the activation parameters has been discussed. PMID:14667714

Bai, Tong-Chun; Yan, Guo-Bing

2003-11-21

454

Femtosecond Chemically Activated Reactions: Concept of Nonstatistical Activation at High Thermal Energies  

E-print Network

Energies Sang Kyu Kim, Ju Guo, J. Spencer Baskin, and Ahmed H. Zewail* Arthur Amos Noyes Chemical Physics Femtosecond chemical activation of reactions at very high thermal energies, much above the bond energy relative to chemical binding energies. A central question relevant here is the following: What

Kim, Sang Kyu

455

Active Control of Flow around NACA 0015 Airfoil by Using DBD Plasma Actuator  

NASA Astrophysics Data System (ADS)

In this study, effect of plasma actuator on a flat plate and manipulation of flow separation on NACA0015 airfoil with plasma actuator at low Reynolds numbers were experimentally investigated. In the first section of the study, plasma actuator which consists of positive and grounded electrode couple and dielectric layer, located on a flat plate was actuated at different frequencies and peak to peak voltages in range of 3-5 kHz and 6-12 kV respectively. Theinduced air flow velocity on the surface of flat plate was measured by pitot tube at different locations behind the actuator. The influence of dielectricthickness and unsteady actuation with duty cycle was also examined. In the second section, the effect of plasma actuator on NACA0015 airfoil was studied atReynolds number 15000 and 30000. Four plasma actuators were placed at x/C = 0.1, 0.3, 0.5 and 0.9, and different electrode combinations were activated by sinusoidal signal. Flow visualizations were done when the attack angles were 0°, 5°, 10°, 15° and 20°. The results indicate that up to the 15° attack angle, the separated flow was reattached by plasma actuator at 12kV peak to peak voltage and 4 kHz frequency. However, 12 kVpp voltage was insufficient to reattach the flow at 20° angle of attack. The separated flow could be reattached by increasing the voltage up to 13 kV. Lift coefficient was also increased by the manipulated flow over the airfoil. Results showed that even high attack angles, the actuators can control the flow separation and prevent the airfoil from stall at low Reynolds numbers.

Akansu, Y. E.; Karakaya, F.; ?anl?soy, A.

2013-04-01

456

Energy Conservation Activities for Elementary Grades (Or: How to Help Slim Down the Energy Monster). Iowa Developed Energy Activities Sampler, Primary K-2.  

ERIC Educational Resources Information Center

The revised Iowa Developed Energy Activity Sampler (IDEAS) was compiled using the original IDEAS program and the Energy Conservation Activity Packets (ECAPS). This booklet provides activities for teachers to use in the primary elementary grades (K-2). The activities are organized into nine units, with units I through VIII containing three…

Iowa State Dept. of Education, Des Moines. Div. of Instructional Services.

457

Energy transport by kinetic-scale electromagnetic waves in fast plasma sheet flows  

NASA Astrophysics Data System (ADS)

We report observations from the THEMIS spacecraft characterizing the nature and importance of low frequency electromagnetic fluctuations on kinetic scales embedded within fast flows in the Earth's plasma sheet. A consideration of wave property variations with frequency and flow speed suggest that for spacecraft frame frequencies satisfying |vf|/ñi ? ùsc ? 100|vf|/ñi (or 0.2 ? fsc ? 20 Hz) these fluctuations can generally be described as kinetic Alfvén waves. Here vf is the flow speed, ñi the ion gyroradius, and ùsc and fsc are the angular and cyclical frequencies respectively in the spacecraft frame. The statistics of energy transport via Poynting flux (S) in these fluctuations and ion energy flux (å) in the flow follow log normal distributions with mean values of = 101.1 ± 0.7 and = 102.4 ± 0.4 mW/m2 respectively where the values are ‘mapped’ to a reference magnetic field at 100 km altitude. Here the indices following ‘ ± ’ correspond to one standard deviation. We find that = 10-1.3 ± 0.7 or that kinetic Alfvén waves on average transport ˜5% of the total energy transport in the flow but note that the values larger than 25% are within one standard de