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1

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

2

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

3

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

4

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

5

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 ...

2010-06-18

6

Magneto-transport properties and thermally activated flux flow activation energies in iron-based superconductors  

NASA Astrophysics Data System (ADS)

We study the magnetotransport properties of three iron-based high temperature superconductors polycrystalline samples, Ba(Fe0.95Ni0.05)2As2 (Tc= 20.4 K), Ba(Fe0.94Ni0.06)2As2 (Tc= 18.5 K), and Ba(Fe0.91Co0.09)2As2 (Tc= 25.3 K), in magnetic fields of up to 18 T. The thermally activated magnetic flux behavior has been retrieved by plotting ? vs. 1/T (? and T are resistivity and temperature, respectively) and obtaining the activation energies U0 for flux motion near Tc. We show a 3-D plot of the distribution of U0 as a function of T and magnetic field H. We apply the WHH model by measuring dHc2/dT at Tc to estimate the upper critical field Hc2(T=0); we estimate the coherence length ?(T=0). We study the broadening of resistive transition as a function of the applied magnetic field and compare it to Tinkham's prediction for high-Tc materials.

Nikolo, Martin; Shi, Xiaoyan; Jiang, J.; Weiss, J. D.; Hellstrom, E. E.

2013-03-01

7

US energy flow, 1991  

SciTech Connect

Trends in energy consumption and assessment of energy sources are discussed. Specific topics discussed include: energy flow charts; comparison of energy use with 1990 and earlier years; supply and demand of fossil fuels (oils, natural gas, coal); electrical supply and demand; and nuclear power.

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

1992-06-01

8

US energy flow, 1982  

SciTech Connect

A flow diagram for 1982 describing the US energy situation is consistent with past conventions. The 70 quads (70 x 10/sup 15/ Btu) of energy consumed is down from 73 quads in 1981 and 75 quads in 1980. The trend reflects a prolonged recession and price driven conservation reflecting the increase in international crude oil prices. Although oil continues to dominate the energy picture by comprising 42% of all energy input, its use continued to decline in 1982. Principal petroleum product reflecting the decline in use is residual oil. Motor gasoline use declined only slightly despite improved fleet mileages. Crude-oil imports absorbed the decline in oil use. Mexico took over as the US's prime supplier with Saudi Arabia as number two. Coal conversions principally for electric-power generation stabilized during 1982 probably because associated capital costs to retrofit oil and gas facilities proved onerous. As a consequence, coal use in the US in 1982 was close to that of 1981. Natural gas use fell largely due to curtailed activity within the industrial sector. Nonetheless, the ratio between energy consumption and GNP as measured in constant dollars fell again. Electric-power generation fell several percent, the first decrese since World War II. Nuclear power provided 12.6% of electrical power with 60 GW/sub e/ available capacity. Coal provided 53%.

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

1983-07-29

9

Lava Flow Activity  

USGS Multimedia Gallery

Activity on the active flow field has been dominated by rootless lava shield construction for the past several weeks (Pu`u `? `?). The main shield, seen here, is topped by a lava pond that feeds overflows down the sides of the shield. Successive overflows slowly build up the he...

2010-06-23

10

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

11

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.

Smith, Clara; Laboratory, Lawrence L.

12

Dynamo Dominated Accretion and Energy Flow: The Mechanism of Active Galactic Nuclei  

NASA Astrophysics Data System (ADS)

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. We suggest here the outlines of such a theoretical understanding and point out where the physical understanding is missing. We 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-? 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. We believe we 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 here are: 1) the Rossby vortex mechanism of the accretion disk viscosity, and 2) the mechanism of the ? - ? 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 ? - ? 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. The predicted form of the emission of both the flux and the magnetic energy density is a force-free magnetic helix extending axially from the disk a distance depending upon its winding number and radius of its flux surfaces, a distance of Mpc's. This Poynting flux of magnetic energy would be invisible unless the currents bounding the magnetic field are dissipated. By definition of force-free, these currents are parallel to the field and throughout its volume. Therefore the dissipation must be throughout the volume as opposed to the conventional reconnection which takes place only at surface layers. This radically different interpretation of reconnection is supported by the observation of "interruption" events in fusion tokamak experiments. Here, and presumably in the galactic case as well, the parallel currents and their dissipation is mediated by run-away, high energy electrons and ions. It is then natural to seek an explanation for the emission spectrum of the dynamo-produced Poynting flux in the same synchrotron emission associated with the dissipation of these run-away currents. We propose the radically different view that these ultra high energy, run-away electrons directly produce the emission spectra as compared to the published models that assume an acceleration of bulk matter to a ? ~ 10 and then reconvert this kinetic energy by shock heating into a highly relativistic plasma, ? ~ 10^6.

Colgate, S. A.; Li, H.

13

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

14

US energy flow, 1981  

NASA Astrophysics Data System (ADS)

Flow diagrams to describe the US energy situation are given. In 1981 the energy consumption was 73 quads (or 73 times 10 to the 15th power Btu). Use was down from 75 quads in 1980. Oil continues to dominate the picture as it comprises 45% of the total energy used. Net oil use (exclusive of oil purchased for the Strategic Petroleum Reserve and Exports) fell 8%; oil imports declined 14%. In contrast to oil, use of natural gas and coal remained at 1980 levels. Decreased use of residual oils, principally for electric power generating, account for much of the drop in oil use. Increased use of coal and nuclear energy for power generation almost compensated for the decrease in use of oil in that end use. Transmitted power remained at 1980 levels. The remainder of the drop in energy usage is attributed to price driven conservation, increased efficiencies in end use and the recession that prevailed during most of the year. The share of the energy drop attributable to the recession is estimated by various analysts to be on the order of 40 to 50%.

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

1982-10-01

15

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

16

Vibrating surface actuators for active flow control  

NASA Astrophysics Data System (ADS)

Current research has shown that aircraft can gain significant aerodynamic performance benefits from active flow control (AFC). AFC seeks to control large scale flows by exploiting natural response triggered by small energy inputs. The principal target application is download alleviation of the V-22 Osprey under the DARPA sponsored Boeing Active Flow Control System program. One method of injecting energy into the flow over the V22 wings is to use an active vibrating surface on the passive seal between the wing and flapperon. The active surface is an oscillating cantilevered beam which injects fluid into the flow, similar to a synthetic jet, and interacts with the flow field. Two types of actuators, or flipperons, are explored. The first is a multilayer piezoelectric polyvinylidene fluoride cantilevered bender. The second is a single crystal piezoelectric (SCP)d31 poled wafer mounted on a cantilevered spring steel substrate. This paper details the development effort including fabrication, mechanical and electrical testing, and modeling for both types of actuators. Both flipperons were mounted on the passive seal between a 1/10th scale V22 wing and flapperon and the aerodynamic performance evaluated in low speed wind tunnel. The SCP flipperon demonstrated significant cruise benefits, with increase of 10 percent lift and 20 percent angle of attack capability. The PVDF flipperon provided a 16 percent drag reduction in the hover mode.

Calkins, Frederick T.; Clingman, Dan J.

2002-07-01

17

California Energy Flow in 1977.  

National Technical Information Service (NTIS)

The supply and use of various forms of energy in California in 1977 has been collected and assembled in an energy flow chart. Overall energy consumption increased 5% in 1977 over 1976; the bulk of the increase was possible because of larger imports of for...

I. Y. Borg

1979-01-01

18

US energy flow, 1990  

Microsoft Academic Search

Energy consumption in the US changed only slightly in 1990. Transportation used was close to 1988 and 1989 levels. Improvements in automobile efficiency were compensated by an increase in the number of miles driven. A larger energy use in the industrial sector was offset by decreases in the residential\\/commercial sector. Energy use in the latter sector was influenced by a

I. Y. Borg; C. K. Briggs

1991-01-01

19

Energy obtained through fluid flows  

SciTech Connect

A system for obtaining energy by means of fluid flows resembling those of a natural cyclone or anti-cyclone comprises a cyclonic conversion tower constituted by a group of convectors all situated round an axis toward which there are directed vortical membranes or screens contained in trumpet-shaped revolution bodies. At its top or bottom the conversion tower optionally bears deflectors or diffusers which increase output. Devices for conversion of electrical or mechanical energy from the kinetic energy of the flow are located at both the top and the base of the tower of convectors. The convection tower optionally is situated on a base which permits the passage of solar radiation with the aim of utilizing its energy, the assembly being completed by a conventional heating system for alternative use.

Valentin, Z.M.

1984-06-05

20

Activation energy measurements of cheese  

Technology Transfer Automated Retrieval System (TEKTRAN)

Temperature sweeps of cheeses using small amplitude oscillatory shear tests produced values for activation energy of flow (Ea) between 30 and 44 deg C. Soft goat cheese and Queso Fresco, which are high-moisture cheeses and do not flow when heated, exhibited Ea values between 30 and 60 kJ/mol. The ...

21

The role of energy exchange between the eddies and the mean flow for the long-term modulation of the solar activity  

NASA Astrophysics Data System (ADS)

The variability of the magnetic features observed in the outer layers of the solar atmosphere is determined by the energetic coupling between the circulation in the convection zone and the solar magnetic field. The 11-year cycle variability is remarkable and was identified few cycles after systematic telescopic observations of sunspots became available. These quasi-periodic oscillations are registered in several parameters such as the total solar irradiance, which is the main external source of energy of the highly coupled Earth's atmospheric/oceanic system. The long-term evolution of the solar activity is also clearly observed in direct and indirect proxies of the solar activity. Periods of low (grand minima) and high (grand maxima) solar activity occurred during the Holocene. However, the precise mechanism that drives the long-term evolution of the solar activity is unknown. Here we show that large storms at the bottom of the convection zone can drive the long-term evolution of the solar activity. We found that the exchange of energy between the mean flow and perturbations of the velocity fields imposed by large cyclonic/anti-cyclonic activity at the bottom of the convection zone is mapped to the outer layers of the solar atmosphere. We anticipate that the relationships found will allow us to model the long-term evolution of the solar cycle activity through the Holocene. We point out that this mechanism requires much less energy them the one based on changes of the meridional circulation. This approach will also help us to constrain the long-term evolution of key solar cycle parameters that are employed to model the long-term evolution of the total and spectral solar irradiance, which are needed to untangle the natural and anthropogenic drivers of the present climate change.

Vieira, L. A.; Dudok de Wit, T.; Da Silva, L. A.

2011-12-01

22

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 worldsâ 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

23

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

24

Observing and Modeling Earth's Energy Flows  

NASA Astrophysics Data System (ADS)

This article reviews, from the authors' perspective, progress in observing and modeling energy flows in Earth's climate system. Emphasis is placed on the state of understanding of Earth's energy flows and their susceptibility to perturbations, with particular emphasis on the roles of clouds and aerosols. More accurate measurements of the total solar irradiance and the rate of change of ocean enthalpy help constrain individual components of the energy budget at the top of the atmosphere to within ±2 W m-2. The measurements demonstrate that Earth reflects substantially less solar radiation and emits more terrestrial radiation than was believed even a decade ago. Active remote sensing is helping to constrain the surface energy budget, but new estimates of downwelling surface irradiance that benefit from such methods are proving difficult to reconcile with existing precipitation climatologies. Overall, the energy budget at the surface is much more uncertain than at the top of the atmosphere. A decade of high-precision measurements of the energy budget at the top of the atmosphere is providing new opportunities to track Earth's energy flows on timescales ranging from days to years, and at very high spatial resolution. The measurements show that the principal limitation in the estimate of secular trends now lies in the natural variability of the Earth system itself. The forcing-feedback-response framework, which has developed to understand how changes in Earth's energy flows affect surface temperature, is reviewed in light of recent work that shows fast responses (adjustments) of the system are central to the definition of the effective forcing that results from a change in atmospheric composition. In many cases, the adjustment, rather than the characterization of the compositional perturbation (associated, for instance, with changing greenhouse gas concentrations, or aerosol burdens), limits accurate determination of the radiative forcing. Changes in clouds contribute importantly to this adjustment and thus contribute both to uncertainty in estimates of radiative forcing and to uncertainty in the response. Models are indispensable to calculation of the adjustment of the system to a compositional change but are known to be flawed in their representation of clouds. Advances in tracking Earth's energy flows and compositional changes on daily through decadal timescales are shown to provide both a critical and constructive framework for advancing model development and evaluation.

Stevens, Bjorn; Schwartz, Stephen E.

2012-07-01

25

California energy flow in 1992  

SciTech Connect

For the past 16 years energy flow diagrams for the State of California have been prepared from available data by members of the Lawrence Livermore National Laboratory. They have proven to be useful tools in graphically expressing energy supply and use in the State as well as illustrating the difference between particular years and between the State and the US as a whole. As far as is possible, similar data sources have been used to prepare the diagrams from year to year and identical assumptions{sup la-le} concerning conversion efficiencies have been made in order to minimize inconsistencies in the data and analyses. Sources of data used in this report are given in Appendix B and C; unavoidably the sources used over the 1976--1993 period have varied as some data bases are no longer available. In addition, we continue to see differences in specific data reported by different agencies for a given year. In particular, reported data on supply and usage in industrial/commercial/residential end-use categories have shown variability amongst the data gathering agencies, which bars detailed comparisons from year to year. Nonetheless, taken overall, valid generalizations can be made concerning gross trends and changes.

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

1994-04-01

26

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

27

Kinetic energy and momentum of preferential flow  

Microsoft Academic Search

Preferential flow in porous media is dominated by the dissipation of momentum whereas ordinary flow (i.e., flow obeying the Richards-Equation) is dominated by the diffusion of capillary potential. Momentum and kinetic energy of preferential flow are computed from controlled infiltration experiments and rapid soil moisture readings with TDR-equipment at various depths in the soil profile. The rapid increases of soil

P. F. Germann

2003-01-01

28

Optimal Power Flow of Multiple Energy Carriers  

Microsoft Academic Search

This paper presents an approach for combined optimization of coupled power flows of different energy infrastructures such as electricity, gas, and district heating systems. A steady state power flow model is presented that includes conversion and transmission of an arbitrary number of energy carriers. The couplings between the different infrastructures are explicitly taken into account based on the new concept

Martin Geidl; Göran Andersson

2007-01-01

29

Kinetic energy and momentum of preferential flow  

NASA Astrophysics Data System (ADS)

Preferential flow in porous media is dominated by the dissipation of momentum whereas ordinary flow (i.e., flow obeying the Richards-Equation) is dominated by the diffusion of capillary potential. Momentum and kinetic energy of preferential flow are computed from controlled infiltration experiments and rapid soil moisture readings with TDR-equipment at various depths in the soil profile. The rapid increases of soil moisture after the beginning of sprinkling at depths between 0.5 and 1.0 m indicate preferential flow to this depth range. However, the associated kinetic energy per unit volume of flow is about 1000 times smaller than the static capillary potential exerted from the matrix. Albeit the large differences between the static and dynamic energies acting on the soil water we conclude that the comparatively small kinetic energy of preferential flow suffices to prevent the capillary potential from attracting all the mobile soil water that moves presumably as films in larger and continuous soil voids. Salt tracer experiments revealed the rapid advancement of salt-free water at some depth in the soil profile, thus parts of the water have been broken lose from the local bonds. We propose that the impact of kinetic energy on flow is independent from the impact of capillary potential. The challenge lies in the investigation of the boundary and initial conditions required to initiate and maintain the impact of kinetic energy on flow, and to explore the time and length scales of its persistence.

Germann, P. F.

2003-04-01

30

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...

2010-06-18

31

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

32

Analysis of Motorcycle Weave Mode by using Energy Flow Method  

NASA Astrophysics Data System (ADS)

The activation mechanism of motorcycle weave mode is clarified within the framework of the energy flow method, which calculates energy flow of mechanical forces in each motion. It is demonstrated that only a few mechanical forces affect the stability of the weave mode from among a total of about 40 mechanical forces. The activation of the lateral, yawing and rolling motions destabilize the weave mode, while activation of the steering motion stabilizes the weave mode. A detailed investigation of the energy flow of the steering motion reveals that the steering motion plays an important role in clarifying the characteristics of the weave mode. As activation of the steering motion progresses the phase of the front tire side force, and the weave mode is consequently stabilized. This paper provides a design guide for stabilizing the weave mode and the wobble mode compatibility.

Marumo, Yoshitaka; Katayama, Tsuyoshi

33

Energy flow in acoustic black holes  

NASA Astrophysics Data System (ADS)

We present the results of an analysis of superradiant energy flow due to scalar fields incident on an acoustic black hole. In addition to providing independent confirmation of the recent results in [E. Berti, V. Cardoso, and J. P. S. Lemos, Phys. Rev. D 70, 124006 (2004).PRVDAQ0556-282110.1103/PhysRevD.70.124006], we determine in detail the profile of energy flow everywhere outside the horizon. We confirm explicitly that in a suitable frame the energy flow is inward at the horizon and outward at infinity, as expected on physical grounds.

Choy, K.; Kruk, T.; Carrington, M. E.; Fugleberg, T.; Zahn, J.; Kobes, R.; Kunstatter, G.; Pickering, D.

2006-05-01

34

Activation parameters of flow through battery separators  

SciTech Connect

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.

1983-05-01

35

Flow stabilization with active hydrodynamic cloaks.  

PubMed

We demonstrate that fluid flow cloaking solutions, based on active hydrodynamic metamaterials, exist for two-dimensional flows past a cylinder in a wide range of Reynolds numbers (Re's), up to approximately 200. Within the framework of the classical Brinkman equation for homogenized porous flow, we demonstrate using two different methods that such cloaked flows can be dynamically stable for Re's in the range of 5-119. The first highly efficient method is based on a linearization of the Brinkman-Navier-Stokes equation and finding the eigenfrequencies of the least stable eigenperturbations; the second method is a direct numerical integration in the time domain. We show that, by suppressing the von Kármán vortex street in the weakly turbulent wake, porous flow cloaks can raise the critical Reynolds number up to about 120 or five times greater than for a bare uncloaked cylinder. PMID:23214882

Urzhumov, Yaroslav A; Smith, David R

2012-11-21

36

California energy flow in 1994.  

National Technical Information Service (NTIS)

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 re...

I. Y. Borg N. Mui

1996-01-01

37

California energy flow in 1991  

Microsoft Academic Search

Energy consumption in California fell in 1991 for the first time in five years. The State`s economy was especially hard hit by a continuing national recession. The construction industry for the second year experienced a dramatic downturn. Energy use in the industrial sector showed a modest increase, but consumption in other end-use categories declined. The decrease in energy used in

I. Y. Borg; C. K. Briggs

1993-01-01

38

Energy Conservation: Student Activities  

NSDL National Science Digital Library

This teacher's guide contains six student activities on the topic of energy conservation and the impact of energy use on society. These materials are developed for use in middle schools for energy-related studies in many different subject areas. The activities each contain objectives, lesson plans, teaching tips, supplementary resources, and references. The top document on this page contains the Introduction and Table of Contents. The Primary Documents link can be opened to access the individual student activities. This is one of several similar modules and activity books regarding science, technology, and societal issues.

2012-01-27

39

California energy flow in 1991.  

National Technical Information Service (NTIS)

Energy consumption in California fell in 1991 for the first time in five years. The State's economy was especially hard hit by a continuing national recession. The construction industry for the second year experienced a dramatic downturn. Energy use in th...

C. K. Briggs I. Y. Borg

1993-01-01

40

Gradient Vector Flow Fast Geodesic Active Contours  

Microsoft Academic Search

This paper proposes a new front propagation flow for boundary extraction. The proposed framework is inspired by the geodesic active contour model and leads to a paradigm that is relatively free from the initial curve po- sition. Towards this end, it makes use of a recently in- troduced external boundary force, the gradient vector field that refers to a spatial

Nikos Paragios; Olivier Mellina-gottardo; Visvanathan Ramesh

2001-01-01

41

Sensitivity of the transverse flow to the symmetry energy  

Microsoft Academic Search

We study the sensitivity of transverse flow to symmetry energy in the Fermi energy region as well as at high energies. We find that transverse flow is sensitive to symmetry energy and 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,

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

2011-01-01

42

Metallurgical technologies, energy conversion, and magnetohydrodynamic flows  

SciTech Connect

The present volume discusses metallurgical applications of MHD, R D on MHD devices employing liquid working medium for process applications, electromagnetic (EM) modulation of molten metal flow, EM pump performance of superconducting MHD devices, induction EM alkali-metal pumps, a physical model for EM-driven flow in channel-induction furnaces, grain refinement in Al alloys via EM vibrational method, dendrite growth of solidifying metal in dc magnetic field, MHD for mass and heat transfer in single-crystal melt growth, inverse EM shaping, and liquid-metal MHD development in Israel. Also discussed are the embrittlement of steel by lead, an open cycle MHD disk generator, the acceleration of gas-liquid piston flows for molten-metal MHD generators, MHD flow around a cylinder, new MHD drag coefficients, liquid-metal MHD two-phase flow, and two-phase liquid gas mixers for MHD energy conversion.

Branover, H.; Unger, Y.

1993-01-01

43

A compact active grid for stirring pipe flow  

NASA Astrophysics Data System (ADS)

A compact active grid is developed with which a pipe flow can be stirred in order to enhance the turbulence. The active grid is composed of a stationary and a rotating disk with characteristic hole patterns. This active grid is placed inside the pipe, allowing flow to pass through it. With only one moving part, the design is much less complicated than current active grids. Several combinations of perforated disks are investigated, and the resulting control over the turbulent intensity and spectral energy distribution is quantified over a wide range of rotation frequencies. We find that significant turbulent fluctuations are introduced mainly in the energy-containing range and partially also in the inertial subrange. These additional fluctuations represent up to 25 % of the total energy and are not caused by pulsations of the mean flow. The compact active grid will be of use where efficient mixing in limited space is required and in applications when the introduction of specific lengthscales is desirable, such as in premixed burners.

Verbeek, A. A.; Pos, R. C.; Stoffels, G. G. M.; Geurts, B. J.; van der Meer, Th. H.

2013-10-01

44

Field Flows of Dark Energy  

SciTech Connect

Scalar field dark energy evolving from a long radiation- or matter-dominated epoch has characteristic dynamics. While slow-roll approximations are invalid, a well defined field expansion captures the key aspects of the dark energy evolution during much of the matter-dominated epoch. Since this behavior is determined, it is not faithfully represented if priors for dynamical quantities are chosen at random. We demonstrate these features for both thawing and freezing fields, and for some modified gravity models, and unify several special cases in the literature.

Cahn, Robert N.; de Putter, Roland; Linder, Eric V.

2008-07-08

45

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

46

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.

C. F. Berger et al.

2002-12-05

47

California Energy Flow in 1979.  

National Technical Information Service (NTIS)

Energy use in California during 1979 differed significantly from 1978. Overall use of natural gas in the state increased substantially (14.3%) due principally to greater use for electrical power production; 47% more gas was used for electrical power gener...

C. K. Briggs I. Y. Borg

1981-01-01

48

California energy flow in 1979  

Microsoft Academic Search

Energy use in California during 1979 differed significantly from 1978. Overall use of natural gas in the state increased substantially (14.3%) due principally to greater use for electrical power production; 4% more gas was used for electrical power generation in 1979 than in 1978 and 21% more than in 1977. Use of fuel oil for electrical generation remained at the

C. K. Briggs; I. Y. Borg

1981-01-01

49

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

50

California energy flow in 1991  

SciTech Connect

Energy consumption in California fell in 1991 for the first time in five years. The State`s economy was especially hard hit by a continuing national recession. The construction industry for the second year experienced a dramatic downturn. Energy use in the industrial sector showed a modest increase, but consumption in other end-use categories declined. The decrease in energy used in transportation can be traced to a substantial fall in the sales of both highway diesel fuels and vessel bunkering fuels at California ports, the latter reflecting a mid-year increase in taxes. Gasoline sales by contrast increased as did the number of miles traveled and the number of automobiles in the State. Production in California`s oil and gas fields was at 1990 levels thus arresting a steady decline in output. Due to enlarged steam flooding operations, production at several fields reached record levels. Also countering the decline in many of California fields was new production from the Port Arguello offshore field. California natural gas production, despite a modest 1991 increase, will not fill the use within the State. Petroleum comprised more than half of the State`s energy supply principally for transportation. Natural gas use showed a small increase. Oil products play virtually no role in electrical production. The largest single source of electricity to the State is imports from the Pacific Northwest and from coal-fired plants in the Southwest. Combined contributions to transmitted electricity from renewable and alternate sources declined as hydropower was constrained by a prolonged drought and as geothermal power from the largest and oldest field at The Geysers fell. Windpower grew slightly; however solar power remained at 1990 levels and made no substantial contribution to total power generation.

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

1993-04-01

51

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

52

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

53

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

54

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

55

Transitioning Active Flow Control to Applications  

Microsoft Academic Search

Active Flow Control Programs at NASA, the U.S.Air Force, and DARPA have been initiated with thegoals of obtaining revolutionary advances inaerodynamic performance and maneuveringcompared to conventional approaches. Theseprograms envision the use of actuators, sensors,and controllers on applications such as aircraftwings\\/tails, engine nacelles, internal ducts,nozzles, projectiles, weapons bays, andhydrodynamic vehicles. Anticipated benefits offlow control include reduced weight, part...

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

1999-01-01

56

Dynamical bottlenecks to intramolecular energy flow.  

PubMed

Vibrational energy flows unevenly in molecules, repeatedly going back and forth between trapping and roaming. We identify bottlenecks between diffusive and chaotic behavior, and describe generic mechanisms of these transitions, taking the carbonyl sulfide molecule OCS as a case study. The bottlenecks are found to be lower-dimensional tori; their bifurcations and unstable manifolds govern the transition mechanisms. PMID:18352620

Paskauskas, R; Chandre, C; Uzer, T

2008-02-27

57

Energy flow with high granularity calorimeters  

NASA Astrophysics Data System (ADS)

In order to perform high precision measurements as well as search for new phenomena at a next Linear Collider, excellent ENERGY FLOW is mandatory. High granularity calorimeters design will fulfill the requests and preliminary results are presented as well as further directions to reach the final performances. .

Gay, P.

2001-07-01

58

Energy End-Use Flow Maps for the Buildings Sector  

SciTech Connect

Graphical presentations of energy flows are widely used within the industrial sector to depict energy production and use. PNNL developed two energy flow maps, one each for the residential and commercial buildings sectors, in response to a need for a clear, concise, graphical depiction of the flows of energy from source to end-use in the building sector.

Belzer, David B.

2006-12-04

59

Sensitivity of the transverse flow to the symmetry energy  

SciTech Connect

We study the sensitivity of transverse flow to symmetry energy in the Fermi energy region as well as at high energies. We find that transverse flow is sensitive to symmetry energy and 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 insensitivity to the symmetry energy at densities {rho}/{rho}{sub 0}>2. The mechanism for the sensitivity of transverse flow to symmetry energy and its density dependence is also discussed.

Gautam, Sakshi; Puri, Rajeev K. [Department of Physics, Panjab University, Chandigarh 160 014 (India); Sood, Aman D.; Aichelin, J. [SUBATECH, Laboratoire de Physique Subatomique et des Technologies Associees, Universite de Nantes, IN2P3/CNRS, Ecole des Mines de Nantes, 4 rue Alfred Kastler, F-44072 Nantes (France)

2011-03-15

60

Energy flow analysis of coupled structures  

NASA Astrophysics Data System (ADS)

Energy flow analysis (EFA) is an analytical tool for prediction of the frequency-averaged vibrational response of built-up structures at high audible frequencies. The procedure is based on two developments; firstly, the derivation of the partial differential equations that govern the propagation of energy-related quantities in simple structural elements such as rods, beams, plates, and acoustic cavities; secondly, the derivation of coupling relationships in terms of energy-related quantities that describe the transfer of energy for various joints (e.g., beam-to-beam, plate-to-plate, and structure-to acoustic field couplings). In this investigation, EFA is used to predict the vibrational response of various coupled structures. In the process of predicting the vibrational response of the coupled structures, the energy flow coupling relationships at the joints of these structures are derived. In addition, the finite element formulation of the governing energy equations are developed. Because the energy density is discontinuous at the joint, a special global assembly procedure is developed to assemble the finite element matrix equations into global matrix equations. The global matrix assembly procedure is predicated on the development of joint element matrix equations using energy flow coupling relationships for various structural joints. The results predicted by EFA for a frame structure with a three-dimensional joint, where four wave types propagate in the structure, are shown to be a reasonable approximation of the frequency-averaged 'exact' energetics, which are computed from classical displacement solutions. The accuracy of the results predicted by EFA increased with high mode count and modal overlap factor or high non-dimensional wavenumber band and non-dimensional damped wavenumber band in the frequency band of interest. An experimental investigation of vibrational response of a light truck frame structure was performed to verify the results of EFA when applied to structures of complicated geometry. The predicted frequency-averaged (one-third octave band) vibrational response of the truck frame structure were in good agreement with the experimental results even with a crude simulation model. The EFA results also showed the important energy transmission mechanisms in these applications to built-up structures.

Cho, Phillip Eung-Ho

1993-01-01

61

U.S. Energy Flow - 1999  

SciTech Connect

Lawrence Livermore National Laboratory (LLNL) has prepared similar flow charts of U.S. energy consumption since 1972. The chart follows the flow of individual fuels and compares these on the basis of a common energy unit of quadrillion British thermal units (Btu). A quadrillion, or ''quad,'' is 10{sup 15}. One Btu is the quantity of heat needed to raise the temperature of 1 pound of water by 1 F at or near 39.2 F. The width of each colored line across this chart is in proportion to the amount of quads conveyed. (Exception: lines showing extremely small amounts have been made wide enough to be clearly visible.) In most cases, the numbers used in this chart have been rounded to the nearest tenth of a quad, although the original data was published in hundredths or thousandths of a quad. As a consequence of independent rounding, some of the summary numbers may not appear to be a precise total of their various components. The first chart in this document uses quadrillion Btu's to conform with data from the U.S. Department of Energy's Energy Information Administration (EIA). However, the second chart is expressed in exajoules. A joule is the metric unit for heat. One Btu equals 1,055.06 joules; and one quadrillion Btu's equals 1.055 exajoules (an exajoule is 10{sup 18} joules).

Kaiper, G V

2001-03-01

62

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.

63

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.

64

Jet energy flow at the LHC  

SciTech Connect

We present a quantitative study of energy flow away from jets by numerically solving the evolution equation derived by Banfi, Marchesini, and Smye, and apply the result to two processes at the LHC: discriminating high-p{sub t} jets originating from decays of heavy electroweak bosons from the QCD background, and the survival probability of the BFKL-initiated dijet rapidity gaps. As a by-product, we find a hidden symmetry of the Banfi, Marchesini, and Smye equation which is a remnant of conformal symmetry.

Hatta, Yoshitaka; Ueda, Takahiro [Graduate School of Pure and Applied Sciences, University of Tsukuba, Tsukuba, Ibaraki 305-8571 (Japan)

2009-10-01

65

Energy flow model for thin plate considering fluid loading with mean flow  

NASA Astrophysics Data System (ADS)

Energy Flow Analysis (EFA) has been developed to predict the vibration energy density of system structures in the high frequency range. This paper develops the energy flow model for the thin plate in contact with mean flow. The pressure generated by mean flow affects energy governing equation and power reflection-transmission coefficients between plates. The fluid pressure is evaluated by using velocity potential and Bernoulli's equation, and energy governing equations are derived by considering the flexural wavenumbers of a plate, which are different along the direction of flexural wave and mean flow. The derived energy governing equation is composed of two kinds of group velocities. To verify the developed energy flow model, various numerical analyses are performed for a simple plate and a coupled plate for several excitation frequencies. The EFA results are compared with the analytical solutions, and correlations between the EFA results and the analytical solutions are verified.

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

2012-11-01

66

Science Activities in Energy: Wind Energy.  

ERIC Educational Resources Information Center

|Included in this science activities energy package are 12 activities related to wind energy for elementary students. Each activity is outlined on a single card and is introduced by a question. Topics include: (1) At what time of day is there enough wind to make electricity where you live?; (2) Where is the windiest spot on your schoolground?; and…

Oak Ridge Associated Universities, TN.

67

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

68

The effects of aging and activity on muscle blood flow  

Microsoft Academic Search

BACKGROUND: Our purpose was to determine if aging had an influence on muscle blood flow independent of habitual physical activity levels. METHODS: Blood flow was measured in the femoral artery by Doppler ultrasound after cuff occlusion of 10 minutes. Active and inactive older subjects (73 ± 7 years) were compared to active and inactive young subjects (26 ± 6 years).

Jennifer L Olive; Allison E DeVan; Kevin K McCully

2002-01-01

69

Finite element models of piezoelectric actuation for active flow control  

Microsoft Academic Search

A numerical procedure, based on the finite element method, capable to simulate the interaction of active structures with an incompressible fluid flow is discussed. In particular the active functionality of such structures is demanded to piezoelectric type actuators. The development of this interaction is connected to the study of problems that involve an active flow control for different potential applications

L. Lampani; R. Grillo; P. Gaudenzi

70

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

71

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

72

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

73

CFD-based aero-optical analysis of flow fields over two-dimensional cavities with active flow control  

NASA Astrophysics Data System (ADS)

Prediction and control of optical wave front distortions and aberrations in a high energy laser beam due to interaction with an unsteady highly non-uniform flow field is of great importance in the development of directed energy weapon systems for Unmanned Air Vehicles (UAV). The unsteady shear layer over the weapons bay cavity is the primary cause of this distortion of the optical wave front. The large scale vortical structure of the shear layer over the cavity can be significantly reduced by employing an active flow control technique combined with passive flow control. This dissertation explores various active and passive control methods to suppress the cavity oscillations and thereby improve the aero-optics of cavity flow. In active flow control technique, a steady or a pulsed jet is applied at the sharp leading edge of cavities of different aspect ratios L/D (=2, 4, 15), where L and D are the width and the depth of a cavity respectively. In the passive flow control approach, the sharp leading or trailing edge of the cavity is modified into a round edge of different radii. Both of these active and passive flow control approaches are studied independently and in combination. Numerical simulations are performed, with and without active flow control for subsonic free stream flow past two-dimensional sharp and round leading or trailing edge cavities using Unsteady Reynolds-Averaged Navier-Stokes (URANS) equations with a two-equation Shear Stress Transport (SST) turbulence model or a hybrid SST/Large Eddy Simulation (LES) model. Aero-optical analysis is developed and applied to all the simulation cases. Index of refraction and Optical Path Difference (OPD) are compared for flow fields without and with active flow control. Root-Mean-Square (RMS) value of OPD is calculated and compared with the experimental data, where available. The effect of steady and pulsed blowing on buffet loading on the downstream face of the cavity is also computed. Using the numerical simulations, the most effective approach for controlling the cavity oscillations and aero-optical signatures is determined.

Tan, Yan

74

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...

75

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…

Oak Ridge Associated Universities, TN.

76

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

77

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

78

Active control of flow and heat transfer in silicon microchannels  

NASA Astrophysics Data System (ADS)

Boiling heat transfer in silicon microchannels needs high walls and liquid superheats for bubble nucleation, leading to a strong thermal non-equilibrium between vapor and liquid phases, which not only damages the heat transfer device at the start-up stage, but also causes two-phase flow instabilities. In this paper, the seed bubble technique is used as an active control strategy to improve the flow and heat transfer in silicon microchannels. Seed bubbles are miniature bubbles of micron size, which are produced on a set of microheaters upstream of microchannels driven by pulse voltage signal. They flow downstream of microchannels after they depart from microheaters to decrease and control the thermal non-equilibrium between vapor and liquid phases in microchannels. The working fluid was methanol and the hydraulic diameter of the microchannels was 100 µm. The demand curves of pressure drops versus mass fluxes were examined with and without active control. Four regions (I, II, III and IV) of demand curves were identified. For the flow without active control, the four regions were the subcooled liquid flow, the superheated liquid flow, the unstable boiling flow and the vapor flow at high-vapor-mass qualities. Alternatively, for the flow with active control, the four regions were the subcooled liquid flow, the seed-bubble-triggered boiling flow, the seed-bubble-stabilized boiling flow and the vapor flow at high-vapor-mass qualities. The linear part of the demand curves is shortened when the seed bubble technique is used. The points at which the demand curves deviate from the linear part coincide into one point at different seed bubble frequencies. The seed bubbles have no influence on the subcooled liquid flow (region I) and the vapor flow at high-vapor-mass qualities (region IV). However, seed bubbles not only convert a superheated liquid flow into a quasi-stable boiling flow in region II, but also convert an unstable boiling flow into a quasi-stable boiling flow in region III. Besides, heat transfer coefficients with active control are several times those without active control in regions II and III. The higher the seed bubble frequencies, the more the heater surface temperatures decrease.

Liu, Guohua; Xu, Jinliang; Yang, Yongping; Zhang, Wei

2010-04-01

79

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

80

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

81

Participant-spectator matter at the energy of vanishing flow  

Microsoft Academic Search

We aim to study the participant-spectator matter over a wide range of energies of vanish- ing flow and masses. For this, we have employed different model parameters at central and semi-central colliding geometries. A nearly mass independent nature of the participant matter has been obtained at the energy of vanishing flow. Further, participant matter can also act as an indicator

Sakshi Gautam; Aman D Sood; Rajeev K Puri

2010-01-01

82

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

83

Electromagnetic energy flow lines as possible paths of photons  

NASA Astrophysics Data System (ADS)

Motivated by recent experiments where interference patterns behind a grating are obtained by accumulating single photon events, we provide here an electromagnetic energy flow-line description to explain the emergence of such patterns. We find and discuss an analogy between the equation describing these energy flow lines and the equation of Bohmian trajectories used to describe the motion of massive particles.

Davidovi?, M.; Sanz, A. S.; Arsenovi?, D.; Boži?, M.; Miret-Artés, S.

2009-07-01

84

Flow in Tubules Due to Ciliary Activity.  

National Technical Information Service (NTIS)

A simplified model for cilia-induced flows in tubules is presented. Each cilium is a long slender body which is constrained to move similar to its beat. An array of cilia is defined and coordinated in such a way as to represent the metachronal wave. The v...

J. Blake

1972-01-01

85

NEED Project: Primary Energy Activities  

NSDL National Science Digital Library

This free activity booklet for Grades 2-4 accompanies the NEED Project's Primary Science of Energy curriculum materials. It contains an array of multisensory games, songs, graphics, and seat activities to accompany the energy instructional unit outlined in the NEED Teacher's Guide for Primary Energy. You'll also find printable assessments with answer keys and a student self-evaluation. The NEED energy curriculum is noteworthy because students are first introduced to energy as a physical science concept before being exposed to sources of energy. Using this sequence can help learners differentiate energy forms (thermal, motion, wave, chemical) from energy sources (fossil fuels, wind, geothermal, hydroelectric). See Related Materials for a link to the Teacher's Guide for this unit. 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.

2013-04-04

86

Analysis of flow cytometry DNA damage response protein activation kinetics after exposure to x rays and high-energy iron nuclei.  

PubMed

We developed a mathematical method to analyze flow cytometry data to describe the kinetics of ?-H2AX and pATF2 phosphorylation in normal human fibroblast cells after exposure to various qualities of low-dose radiation. Previously reported flow cytometry kinetics 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 revealed significant differences between control and low-dose samples when distributions were compared using the Kolmogorov-Smirnov test. Differences in radiation quality were found in the distribution shapes and when a nonlinear model was used to relate dose and time to the decay of the mean ratio of phospho-protein 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 ?-H2AX were higher after exposure to iron nuclei compared to X rays in G(1) cells and in S/G(2) cells. The RBE in G(1) cells for iron nuclei relative to X rays for ?-H2AX was 2.1 ± 0.6 and 5.0 ± 3.5 at 2 and 24 h after irradiation, respectively. For pATF2, a saturation effect was observed with reduced expression at high doses, especially for iron nuclei, with much slower characteristic repair times (>7 h) compared to X rays. RBEs for pATF2 were 0.7 ± 0.1 and 1.7 ± 0.5 at 2 and 24 h, respectively. Significant differences in ?-H2AX and pATF2 levels when irradiated samples were compared to controls were noted even at the lowest dose analyzed (0.05 Gy). These results show that mathematical models can be applied to flow cytometry data to identify important and subtle differences after exposure to various qualities of low-dose radiation. PMID:21128792

Chappell, Lori J; Whalen, Mary K; Gurai, Sheena; Ponomarev, Artem; Cucinotta, Francis A; Pluth, Janice M

2010-09-28

87

A new energy transfer model for turbulent free shear flow  

Microsoft Academic Search

A new model for the energy transfer mechanism in the large-scale turbulent kinetic energy equation is proposed. An estimate of the characteristic length scale of the energy containing large structures is obtained from the wavelength associated with the structures predicted by a weakly nonlinear analysis for turbulent free shear flows. With the inclusion of the proposed energy transfer model, the

William W.-W. Liou

1992-01-01

88

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.

Simon, A. J.; Belles, R. D.; Lab, Lawrence L.

89

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

90

International Energy Agency Activities  

Microsoft Academic Search

Hydrogen systems can provide viable, sustainable options for meeting the world's energy requirements. Hydrogen is relevant to all of the energy sectors - transportation, buildings, utilities and industry. It can provide storage options for baseload (geothermal), seasonal (hydroelectric) and intermittent (PV and wind) renewable resources, and, when combined with emerging decarbonization technologies, can reduce the climate impacts of continued fossil

Carolyn C. Elam; Catherine E. Grégoire Padró; Pamela L. Spath

2002-01-01

91

Monitoring Industrial Energy and Carbon flows  

Microsoft Academic Search

For a proper assessment of the impact of global energy use on the climate system, consistent and reliable monitoring of energy use, energy related greenhouse gas (GHG) emissions and energy efficiency developments is of vital importance. This thesis aims to improve the monitoring of energy use, carbon dioxide (CO2) emissions and energy efficiency for the industrial sector. In the first

M. L. Neelis

2008-01-01

92

Aerodynamic Flow Control using Distributed Active Bleed  

NASA Astrophysics Data System (ADS)

The aerodynamic effects of large-area air bleed that is driven through surface openings by pressure differences across a lifting airfoil and regulated by addressable, arrays of integrated louvers have been investigated in wind tunnel experiments. Time-dependent interactions between the bleed and cross flows alter the apparent aerodynamic shape of the lifting surface and consequently the distributions of aerodynamic forces and moments. The lift and pitching moment can be significantly altered over a wide range of angles of attack from pre- to post-stall by independently-controlled bleed near the leading (LE) and trailing (TE) edges. While TE bleed effects nearly-linear variation of the pitching moment with minimal changes in lift, LE bleed leads to large variations in lift and pitching moment with minimal drag penalty. Phase-locked PIV shows the effects of the bleed on the flow on the suction surface and in the near wake. Supported by AFOSR

Kearney, John M.; Glezer, Ari

2010-11-01

93

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...

94

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...

2010-05-20

95

The Role of Water Vapour in Earth's Energy Flows  

NASA Astrophysics Data System (ADS)

Water vapour modulates energy flows in Earth's climate system through transfer of latent heat by evaporation and condensation and by modifying the flows of radiative energy both in the longwave and shortwave portions of the electromagnetic spectrum. This article summarizes the role of water vapour in Earth's energy flows with particular emphasis on (1) the powerful thermodynamic constraint of the Clausius Clapeyron equation, (2) dynamical controls on humidity above the boundary layer (or free-troposphere), (3) uncertainty in continuum absorption in the relatively transparent "window" regions of the radiative spectrum and (4) implications for changes in the atmospheric hydrological cycle.

Allan, Richard P.

2012-07-01

96

Active Control of Tip Leakage Flows  

NASA Astrophysics Data System (ADS)

The performance of axial compressors is degraded by the leakage of fluid from the high-pressure side of the blade to the low pressure side through the narrow gap between the rotating blade and the stationary casing. Controlling such leakage can improve stage performance and improve compressor stability. We report on two methods to control such tip leakage flows using momentum injection located on the casing wall. The first method uses a synthetic jet to create a fluidic wall which reduces the effective gap between the blade and the casing and thus reduces mass flow for a given pressure difference. The second control method artificially forces the tip leakage jet at its natural frequency, increasing its spreading rate, and thus reducing the total pressure loss in the compressor passage. Experimental results from both prototypical experimental rigs and a full compressor cascade rig are presented illustrating the dependence on actuator amplitude, forcing frequency, and geometric variations on the success and cost of both control methods.

Breuer, Kenneth; Bae, Jinwoo; Kang, Eugene; Tan, Choon

1999-11-01

97

Transverse in-plane flow: a new probe of symmetry energy in Fermi energy region  

Microsoft Academic Search

We study the sensitivity of transverse flow towards the different density dependence of symmetry energy in Fermi energy region. Our results show that transverse flow shows sensitivity to different density dependence of symmetry energy. The mechanism for sensitivity towards different density dependence of symmetry energy is also discussed.

Sakshi Gautam; Rajeev K. Puri

2011-01-01

98

Motion Energy Dissipation in Traffic Flow on a Curved Road  

NASA Astrophysics Data System (ADS)

We investigate the energy loss of vehicles running on a curved road. The energy dissipation model for traffic flow is derived. Simulations are carried out to examine the energy dissipation in traffic flow on a curved road with friction coefficient and radii of curvature. Results analysis show that the total energy dissipation increases with an increase in the friction coefficient and radii of curvature. Moreover, the energy dissipation rate varies with the density and road length, which is in good agreement with the real traffic situations.

Zhu, Wen-Xing

2013-07-01

99

Harvesting energy from water flow over graphene.  

PubMed

Water flow over carbon nanotubes has been shown to generate an induced voltage in the flow direction due to coupling of ions present in water with free charge carriers in the nanotubes. However, the induced voltages are typically of the order of a few millivolts, too small for significant power generation. Here we perform tests involving water flow with various molarities of hydrochloric acid (HCl) over few-layered graphene and report order of magnitude higher induced voltages for graphene as compared to nanotubes. The power generated by the flow of ?0.6 M HCl solution at ?0.01 m/sec was measured to be ?85 nW for a ?30 × 16 ?m size graphene film, which equates to a power per unit area of ?175 W/m(2). Molecular dynamics simulations indicate that the power generation is primarily caused by a net drift velocity of adsorbed Cl(-) ions on the continuous graphene film surface. PMID:21749100

Dhiman, Prashant; Yavari, Fazel; Mi, Xi; Gullapalli, Hemtej; Shi, Yunfeng; Ajayan, Pulickel M; Koratkar, Nikhil

2011-07-14

100

Passive and Active Flow Control by Swimming Fishes and Mammals  

NASA Astrophysics Data System (ADS)

What mechanisms of flow control do animals use to enhance hydrodynamic performance? Animals are capable of manipulating flow around the body and appendages both passively and actively. Passive mechanisms rely on structural and morphological components of the body (i.e., humpback whale tubercles, riblets). Active flow control mechanisms use appendage or body musculature to directly generate wake flow structures or stiffen fins against external hydrodynamic loads. Fish can actively control fin curvature, displacement, and area. The vortex wake shed by the tail differs between eel-like fishes and fishes with a discrete narrowing of the body in front of the tail, and three-dimensional effects may play a major role in determining wake structure in most fishes.

Fish, F. E.; Lauder, G. V.

2006-01-01

101

Neutrophil adhesion and activation under flow  

PubMed Central

Neutrophil recruitment into inflamed tissue in response to injury or infection is tightly regulated. Reduced neutrophil recruitment can result in a reduced ability to fight invading microorganisms. During inflammation, neutrophils roll along the endothelial wall of postcapillary venules and integrate inflammatory signals. Neutrophil activation by selectins and chemokines regulates integrin adhesiveness. Binding of activated integrins to their counter-receptors on endothelial cells induces neutrophil arrest and firm adhesion. Adherent neutrophils can be further activated to undergo cytoskeletal rearrangement, crawling, transmigration, superoxide production and respiratory burst. Signaling through G-protein coupled receptors, selectin ligands, Fc receptors and outside-in signaling of integrins are all involved in neutrophil activation, but their interplay in the multistep process of recruitment are only beginning to emerge. This review provides an overview of signaling in rolling and adherent neutrophils.

Zarbock, Alexander; Ley, Klaus

2009-01-01

102

Active Control of Compressible Flow-Induced Cavity Oscillations  

NASA Astrophysics Data System (ADS)

Flow-induced cavity oscillations are characterized by a complex feedback process. Convective instabilities grow to saturation in a shear layer, which then impinges near the downstream corner of the cavity, thereby generating disturbances that travel upstream to the separation edge. The feedback loop is closed via a receptivity process whereby some of the disturbance energy is converted to an instability wave at the separation edge. As a result, large amplitude discrete tones are generated in and around the cavity. Here we report on active control experiments at subsonic compressible speeds aimed at suppressing the acoustic levels. Active control was attempted with piezoelectric flap actuators and unsteady blowing, both at the leading edge of the cavity. The design of the actuators is summarized. In addition, open- and closed-loop control experiments are described. The open-loop control employs sinusoidal forcing at a frequency that is different than the preferred modes of oscillation. The real-time, closed-loop, adaptive control schemes, which incorporate system identification techniques, seek to cancel the instability wave generated by the feedback process.

Cattafesta, Louis N., III; Shukla, Deepak; Garg, Sanjay

1998-11-01

103

Participant-spectator matter at the energy of vanishing flow  

SciTech Connect

We aim to study the participant-spectator matter over a wide range of energies of vanishing flow and masses. For this, we have employed different model parameters at central and semicentral colliding geometries. A nearly mass independent nature of the participant matter has been obtained at the energy of vanishing flow. Further, participant matter can also act as an indicator to study the degree of thermalization.

Sood, Aman D.; Puri, Rajeev K. [Department of Physics, Panjab University, Chandigarh 160 014 (India)

2009-06-15

104

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

105

Tracking the energy flow along the reaction path  

PubMed Central

We report a comprehensive study of the quantum-state correlation property of product pairs from reactions of chlorine atoms with both the ground-state and the CH stretch-excited CHD3. In light of available ab initio theoretical results, this set of experimental data provides a conceptual framework to visualize the energy-flow pattern along the reaction path, to classify the activity of different vibrational modes in a reactive encounter, to gain deeper insight into the concept of vibrational adiabaticity, and to elucidate the intermode coupling in the transition-state region. This exploratory approach not only opens up an avenue to understand polyatomic reaction dynamics, even for motions at the molecular level in the fleeting transition-state region, but it also leads to a generalization of Polanyi's rules to reactions involving a polyatomic molecule.

Yan, Shannon; Wu, Yen-Tien; Liu, Kopin

2008-01-01

106

Stocks, Flows, and Prospects of Energy  

SciTech Connect

Analyses of future energy systems have typically focused on energy sufficiency and climate change issues. While the potential supply of energy services will probably not constrain us in the immediate future, there are limits imposed on the energy system by climate change considerations, which, in turn, are inextricably bound up with land, water, and nonrenewable mineral resources issues. These could pose constraints to energy systems that may not have been fully accounted for in current analyses. There is a pressing lack of knowledge on the boundaries that will impact a sustainable energy system. A more integrated view of energy sustainability is necessary to ensure the well-being of current and future generations. This chapter proposes a set of measures related to sustainability within the context of selected energy scenarios and develops a methodology to define and measure relevant quantities and important links to other resource areas.

Loschel, Andrea [The Centre for European Economic Research (ZEW); Johnston, John [Exxon Mobil Research and Engineering; Delucchi, Mark A [University of California, Davis; Demayo, Trevor N [Chevron, USA; Gautier, Donald L [U.S. Geological Survey; Greene, David L [ORNL; Ogden, Joan [University of California, Davis; Rayner, Steve [University of Oxford; Worrell, Ernst [Ecofys

2010-01-01

107

Drag reduction by active control for flow past cylinders  

Microsoft Academic Search

The main objective of this article is to investigate computational methods for the active control and drag optimization of\\u000a incompressible viscous flow past cylinders, using the two-dimensional Navier-Stokes equations as the flow model. The computational\\u000a methodology relies on the following ingredients: space discretization of the Navier-Stokes equations by finite element approximations,\\u000a time discretization by a second order accurate two step

J.-W. He; M. Chevalier; R. Glowinski; R. Metcalfe; A. Nordlander; J. Periaux

108

Energy amplification in channel flow over riblets  

Microsoft Academic Search

A number of methods of reducing the drag over airfoils have been investigated. This paper considers the use of riblets, which are structures that run parallel to one another that are positioned longitudinally to the flow. It has been shown experimentally that when the shape, spacing and height of the riblets are optimized, the drag coefficient can be reduced by

Stephen Duncan; Antonis Papachristodoulou

2011-01-01

109

Increased platelet activation in patients with slow coronary flow  

Microsoft Academic Search

We tested the hypothesis that increased platelet activation may be present in patients with slow coronary flow (SCF) and may\\u000a contribute to the pathogenesis of slow coronary flow phenomenon (SCFP). Fifty patients angiographically proven normal coronary\\u000a flow (control group; mean age = 61.3 ± 7.0 years, 43 male) and 50 patients with angiographically proven SCF in all coronary\\u000a arteries (patient group; man age = 62.7 ± 6.7 years, 38 male)

Turgay Celik; U. Cagdas Yuksel; Baris Bugan; Atila Iyisoy; Murat Celik; Sait Demirkol; Halil Yaman; Hurkan Kursaklioglu; Selim Kilic; Ersoy Isik

2010-01-01

110

Energy flow principles of IGBT inverters in wind energy conversion systems  

Microsoft Academic Search

Two energy flow principles, defined as the voltage magnitude control principle (MCP) and the voltage phase control principle (PCP), are presented in this paper for wind energy conversion (WEC) grid-connected inverter systems using insulated-gate bipolar transistors (IGBTs). The MCP is for the WEC system to produce a correct energy flow from the wind turbine to the grid by adequate voltage

Hong Huang; Liuchen Chang

2000-01-01

111

Flow visualization using momentum and energy transport tubes and applications to turbulent flow in wind farms  

NASA Astrophysics Data System (ADS)

As a generalization of the mass-flux based classical stream-tube, the concept of momentum and energy transport tubes is discussed as a flow visualization tool. These transport tubes have the property, respectively, that no fluxes of momentum or energy exist over their respective tube mantles. As an example application using data from large-eddy simulation, such tubes are visualized for the mean-flow structure of turbulent flow in large wind farms, in fully developed wind-turbine-array boundary layers. The three-dimensional organization of energy transport tubes changes considerably when turbine spacings are varied, enabling the visualization of the path taken by the kinetic energy flux that is ultimately available at any given turbine within the array.

Meyers, Johan; Meneveau, Charles

2013-01-01

112

Energy efficiency and grain quality characteristics of cross-flow and concurrent-flow dryers  

SciTech Connect

An experimental and simulation study was conducted on the state-of-the-art of US on-farm and off-farm corn drying technology. Experimental data were collected on four commercial cross-flow and one concurrent-flow dryers in four Midwestern states. Each of the dryers was analyzed in depth by simulation. Energy efficiency and grain quality were employed as the criteria for dryer evaluation. Recirculation of exhaust air in cross-flow dryers was found to save as much as 30 percent of the required energy at a cost of about 10-15% on dryer capacity. Reversal of the direction of airflow in the drying section of a cross-flow dryer results in a significant decrease in the moisture content gradient of the outlet grain. Mixing the grain after partial drying in a cross-flow dryer and tempering it before final drying/cooling, further decreases this moisture gradient. The most sophisticated cross-flow dryer combines grain mixing and air recycling with an option to vary the velocity of the grain on the two sides of the individual drying/cooling columns. This design leads to energy efficiency and grain quality characteristics which rival those of multi-stage concurrent-flow dryers. The energy consumption of a differential grain speed cross-flow dryer (DGSCF) is less than 50% of that of a conventional non-recycling cross-flow model. The optimum grain speed ratio in a DGSCF dryer depends on the type of product, the initial product moisture content and the inlet air temperature; the speed ratio varies from 2:1 to 4:1 with the drying product closest to the air inlet flowing at the greater velocity. A further advantage of the DGSCF dryer is the shorter time at which the product is kept at high temperatures compared to other types of cross-flow dryers. The multi-stage concurrent-flow dryer with counterflow cooler proved to be the best of the five dryers analyzed with respect to energy efficiency and grain quality characteristics.

Rodriguez, J.C.

1982-01-01

113

Dynamics of interaction of directed energy flows with matter  

Microsoft Academic Search

Directed energy flows (DEF), including a High Power ion beams (PIB), are used in different areas of science, engineering and technology. For example, very worth-while is the use of PIB for: the realization of inertial controlled fusion, pumping up gas lasers, the investigations in the area of nuclear physics and energy high density physics, the formation of powerful pulse sources

Vladimir A. Skvortsov; Vladimir E. Fortov

1992-01-01

114

Flow of energy in an urban society  

SciTech Connect

This article attempts to assess how a modern urban area consumes energy either directly or indirectly. One of the most important outcomes of this study is a complete picture of an urban energy system, i.e., the entire source-service fuel cycle involving the sources, transportation modes, distribution channels, and consumption pattern of all the energy carriers for a period of 10 years (980--90) for Bangalore, a city in southern India. The study also led to a detailed end-use analysis of energy carriers, and a source-service matrix is prepared for Bangalore. The impact of energy consumption on forests, environment, transportation, and the economy as a whole is discussed here.

Reddy, B.S. [Indira Gandhi Inst. of Development Research, Bombay (India)

1997-04-01

115

Thermally activated plastic flow in the presence of multiple obstacle types  

NASA Astrophysics Data System (ADS)

The rate- and temperature-dependent plastic flow in a material containing two types of thermally activatable obstacles to dislocation motion is studied both numerically and theoretically in a regime of relative obstacle densities for which the zero-temperature stress is additive. The numerical methods consider the low-density ‘forest’ obstacles first as point obstacles and then as extended obstacles having a finite interaction length with the dislocation, while the high-density ‘solute’ obstacles are treated as point obstacles. Results show that the finite-temperature flow stresses due to different obstacle strengthening mechanisms are additive, as proposed by Kocks et al, only when all strengthening obstacles can be approximated as point-like obstacles. When the activation distance of the low-density extended obstacles exceeds the spacing between the high-density obstacles, the finite-temperature flow stress is non-additive and the effective activation energy differs from that of the Kocks et al model. An analytical model for the activation energy versus flow stress is proposed, based on analysis of the simulation results, to account for the effect of the finite interaction length. In this model, for high forest activation energies, the point-pinning solute obstacles provide a temperature-dependent backstress ?b on dislocation and the overall activation energy is otherwise controlled by the forest activation energy. The model predictions agree well with numerical results for a wide range of obstacle properties, clearly showing the effect due to the finite interaction between dislocation and the obstacles. The implications of our results on the activation volume are discussed with respect to experimental results on solute-strengthened fcc alloys.

Dong, Y.; Curtin, W. A.

2012-10-01

116

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

117

Energy efficiency and grain quality characteristics of cross-flow and concurrent-flow dryers  

Microsoft Academic Search

An experimental and simulation study was conducted on the state-of-the-art of US on-farm and off-farm corn drying technology. Experimental data were collected on four commercial cross-flow and one concurrent-flow dryers in four Midwestern states. Each of the dryers was analyzed in depth by simulation. Energy efficiency and grain quality were employed as the criteria for dryer evaluation. Recirculation of exhaust

1982-01-01

118

Lawrence Livermore Laboratory Geothermal Energy Program. A Status Report on the Development of the Total-Flow Concept.  

National Technical Information Service (NTIS)

The technology development activities of the Geothermal Energy Program at the Lawrence Livermore Laboratory are summarized. Significant progress toward development of the Total-Flow concept was made during FY 1978. The results show that the original goal ...

A. L. Austin A. W. Lundberg

1978-01-01

119

Energy flow through a nonambipolar Langmuir sheath  

SciTech Connect

When electrons travel through the sheath toward a plasma-facing surface, they lose a part of their kinetic energy due to the negative work of the electric field in the sheath. What happens to this energy? Does it need to be accounted for if one needs to calculate an energy flux to a wall? In this note, the above questions are answered for three different cases of the boundary conditions: (a) electrically isolated surface charged to a steady-state value corresponding to a floating potential; (b) an isolated wall not yet charged to the floating potential; and (c) biased electrode conducting a steady-state current. The answers are found to be different in each case, but the general conclusion is that to evaluate surface power deposition due to particle bombardment, electron and ion energy fluxes need to be calculated at the wall, and not in the quasineutral plasma.

Dorf, L. A. [Applied Materials, Santa Clara, California 95054 (United States); Semenov, V. E. [Institute of Applied Physics RAS, Nizhny Novgorod 603950 (Russian Federation)

2009-07-15

120

Interfacial Energy Balance Equation for Thermocapillary Flows  

NASA Astrophysics Data System (ADS)

Existing theories for the surface-tension-driven Benard convection (Marangoni convection) have only considered thermocapillary effects through the shear stress balance equation at the interface via the surface-tension-gradient-induced shear stresses. Thermocapillary induced surface energy variation has been ignored all together in these theories. A formulation taking into account this surface energy variation shows that it can have a non-negligible effect on the onset of Benard convection cells.

Chen, Kang Ping

1997-11-01

121

Mechanical energy and power flow of the upper extremity in manual wheelchair propulsion  

Microsoft Academic Search

Objective. To investigate the characteristics of mechanical energy and power flow of the upper limb during wheelchair propulsion. Design. Mechanical energy and power flow of segments were calculated. Background. Very few studies have taken into account the mechanical energy and power flow of the musculoskeletal system during wheelchair propulsion. Mechanical energy and power flow have proven to be useful tools

Lan-Yuen Guo; Fong-Chin Su; Hong-Wen Wu

2003-01-01

122

Mechanical energy and power flow of the upper extremity in manual wheelchair propulsion  

Microsoft Academic Search

Objective. To investigate the characteristics of mechanical energy and power flow of the upper limb during wheelchair propulsion.Design. Mechanical energy and power flow of segments were calculated.Background. Very few studies have taken into account the mechanical energy and power flow of the musculoskeletal system during wheelchair propulsion. Mechanical energy and power flow have proven to be useful tools for investigating

Lan-Yuen Guo; Fong-Chin Su; Hong-Wen Wu; Kai-Nan An

2003-01-01

123

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.

124

Device for deriving energy from a flow of fluid  

SciTech Connect

Improved process and device for extracting energy present in a flowing fluid medium wherein a supported hub with propellers or blades is placed in said medium and the blades are provided with a wing or vane at the tip. The wing is of such a form that it generates a ''venturi effect'' in the flowing medium by which a part of the fluid which should normally pass outside the propeller disc area, is drawn into the propeller. The improvement consists of mixing of fluid which normally should pass outside the venturi with fluid which has flowed through the blades by provisions on blades and/or wing or vanes.

van Holten, T.

1982-12-07

125

Overview of active flow control at NASA Langley Research Center  

Microsoft Academic Search

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

Latunia G. Pack; Ronald D. Joslin

1998-01-01

126

Closed-Loop Active Flow Control - A Collaborative Approach  

Microsoft Academic Search

The Collaborative Center of Control Science (CCCS) at The Ohio State University was founded very recently with funding from the Air Force Research Laboratory to conduct multidisciplinary research in the area of feedback control, with applications such as cooperative control of unmanned air vehicles (UAVs), guidance and control of hypersonic vehicles, and closed-loop active flow control. The last topic is

M. Samimy; M. Debiasi; E. Caraballo; J. DeBonis; J. H. Myatt

2003-01-01

127

Active mantle flow and crustal dynamics in southern California  

Microsoft Academic Search

We present numerical modeling analysis of active upper mantle flow and its role in driving crustal deformation in southern California. The forces driving lithospheric deformation at tectonic plate boundaries can be thought of as the sum from two sources: (1) forces transmitted from the far-field by rigid tectonic plates, and (2) forces created locally at the plate boundary by heterogeneous

N. Fay; R. Bennett; J. Spinler

2007-01-01

128

Observations of subsonic and supersonic shear flows in laser driven high-energy-density plasmas  

Microsoft Academic Search

Shear layers containing strong velocity gradients appear in many high-energy-density (HED) systems and play important roles in mixing and the transition to turbulence. Yet few laboratory experiments have been carried out to study their detailed evolution in this extreme environment where plasmas are compressible, actively ionizing, often involve strong shock waves and have complex material properties. Many shear flows produce

E. C. Harding

2009-01-01

129

Gaseous micro-emboli activity during cardiopulmonary bypass in adults: pulsatile flow versus nonpulsatile flow.  

PubMed

Cardiopulmonary bypass (CPB) has a risk of cerebral injury, with an important role of gaseous micro-emboli (GME) coming from the CPB circuit. Pulsatile perfusion is supposed to perform specific conditions for supplementary GME activity. We aimed to determine whether pulsatile CPB augments production and delivery of GME and evaluate the role of different events in GME activity during either type of perfusion. Twenty-four patients who underwent on-pump coronary artery bypass grafting surgery at the University of Verona were divided equally into two groups-pulsatile perfusion (PP) group and nonpulsatile perfusion (NP) group. The circuit included a JostraHL-20 roller pump set in pulsatile or nonpulsatile mode, an open Sorin Synthesis membrane oxygenator with integrated screen-type arterial filter, and phosphorylcholine-coated tubes. Hemodynamic flow evaluation was performed in terms of energy equivalent pressure and surplus hemodynamic energy (SHE). GME were counted by means of a GAMPT BCC200 bubble counter (GAMPT, Zappendorf, Germany) with two probes placed at postpump and postarterial filter positions. Results were evaluated in terms of GME number, GME volume, number of over-ranged GME from both probes, and series of filtering indexes. In PP mode, the pump produced and delivered along the circuit significantly higher amounts of SHE than in NP mode. At the venous postpump site, GME number was significantly higher during PP but no difference was found in terms of GME volume or number of over-ranged bubbles. No significant difference in GME number, GME volume, or number of over-ranges was found at the postarterial filter site. Filtering indexes were similar between the two groups. Neither type of perfusion was shown to contribute to excessive GME production during the most important perfusionist manipulation. Pulsatility leads to GME increment by splitting and size diminishing of the existing bubbles but not by additional gas production. PP augmented GME number at the venous postpump site, while mean volume remained comparable with NP. Sorin Synthesis oxygenator showed high efficacy in GME removal during either type of perfusion. Supplementary GME production and delivery during typical perfusionist manipulations did not depend on perfusion type. PMID:23489040

Dodonov, Mikhail; Milano, Aldo; Onorati, Francesco; Dal Corso, Bruno; Menon, Tiziano; Ferrarini, Daniele; Tessari, Maddalena; Faggian, Giuseppe; Mazzucco, Alessandro

2013-03-13

130

Dynamics of a deformable active particle under shear flow  

NASA Astrophysics Data System (ADS)

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.

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

2013-09-01

131

Analysis of Energy Flow During Playground Surface Impacts.  

PubMed

The amount of energy dissipated away from or returned to a child falling onto a surface will influence fracture risk but is not considered in current standards for playground impact-attenuating surfaces. A two-mass rheological computer simulation was used to model energy flow within the wrist and surface during hand impact with playground surfaces, and the potential of this approach to provide insights into such impacts and predict injury risk examined. Acceleration data collected on-site from typical playground surfaces and previously-obtained data from children performing an exercise involving freefalling with a fully-extended arm provided input. The model identified differences in energy flow properties between playground surfaces and two potentially harmful surface characteristics: more energy was absorbed by (work done on) the wrist during both impact and rebound on rubber surfaces than on bark, and rubber surfaces started to rebound (return energy to the wrist) while the upper limb was still moving downwards. Energy flow analysis thus provides information on playground surface characteristics and the impact process, and has the potential to identify fracture risks, inform the development of safer impact-attenuating surfaces, and contribute to development of new energy-based arm fracture injury criteria and tests for use in conjunction with current methods. PMID:23182916

Davidson, Peter L; Wilson, Suzanne J; Chalmers, David J; Wilson, Barry D; Eager, David; McIntosh, Andrew S

2012-11-21

132

Direct contact condenser model for high energy laser exhaust flows  

SciTech Connect

A heat transfer model is developed for estimating the thermal performance of direct contact packed bed condensers operating in the effluent stream of a high energy chemical laser. Using a control volume approach, mass and energy balances are applied to the process fluids in conjunction with an empirical correlation for the condenser's volumetric heat transfer coefficient. The model is demonstrated both independently and as an extension to a steam ejector program analyzing pressure recovery of laser exhaust flows. 14 references.

Schreiber, H.; Truman, C.R.; Acebal, R.

1988-01-01

133

A Fluctuating Energy Model for Dense Granular Flows  

Microsoft Academic Search

\\u000a We address the slow, dense flow of granular materials as a continuum with the incompressible Navier-Stokes equations plus\\u000a the fluctuating energy balance for granular temperature. The pseudo-fluid is given an apparent viscosity, for which we choose\\u000a an Arrhenius-like dependence on granular temperature; the fluctuating energy balance includes a ‘mobility enhancing’ term\\u000a due to shear stress and a jamming, dissipative term

Riccardo Artoni; Andrea Santomaso; Paolo Canu

134

Excitation energy flow in chlorosome antennas of green photosynthetic bacteria  

Microsoft Academic Search

Energy flow in whole cells of the thermophilic green photosynthetic bacterium Chloroflexus aurantiacus was studied by measurements of time-resolved fluorescence spectra in the picosecond time range, detected by both streak camera and single-photon counting methods. These data characterize the energy-transfer sequence from bacteriochlorophyll c (BChl c), found in membrane-associated antenna structures called chlorosomes, to BChl a in the chlorosome baseplate,

Mamoru Mimuro; Tsunenori Nozawa; Naoto Tamai; Iwao Yamazaki; Keizou Shimada; Su Lin; Robert S. Knox; Bruce P. Wittmershaus; Daniel C. Brune; Robert E. Blankenship

1989-01-01

135

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

136

Energy balance and physical activity.  

PubMed

The prevalence of obesity is increasing in most parts of the world and becoming one of the major global public health problems. Although the components of energy balance have not been adequately estimated over time, available evidence suggests that the increase in obesity is the result of reduced physical activity. Increases in physical activity have been shown to be strongly associated with improving physical fitness and body composition, with probably a positive effect on resting metabolic rate. The Surgeon General's Report on Physical Activity and Health advocates that 30 min of regular, moderate-intensity physical activity is associated with decreases in the risk of chronic diseases and may contribute to quality of life. However, the small changes that contribute 10 min for 3 times a day for aerobic training, or one set instead of three sets of repetitions on resistance training will provide individuals with health benefits. Indeed, nutrition and physical activity should be considered an integral part of fitness and good health, and should be encouraged in all age groups, particularly early in life. The question is no longer centered around the health benefit of increasing physical activity, but rather creating self awareness and behavior changes in individuals. Hence, effective intervention programs are needed that foster long term changes in physical activity. Among various interventions, the Nutrifit program was recently conducted in Thailand and found to improve health related fitness in children. The development of more effective interventions and approaches is a major challenge in this field today. PMID:11594471

Kuboonchoo, K

2001-06-01

137

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

138

Mass and energy flow in the solar chromosphere and corona  

Microsoft Academic Search

The work reviews some investigations into the mass and energy flow in the solar chromosphere and corona; 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 can also be applied to the study of the outer atmospheres of other stars.

G. L. Withbroe; R. W. Noyes

1977-01-01

139

EERE Energy Education: Energy Science Projects and Activities  

NSDL National Science Digital Library

This website contains links to a collection of simple activities and projects that relate to energy. There are activities for grades K-12, and the activities are divided by grade level. Many of the activities focus on how society uses energy and on renewable vs nonrenewable energy.

2006-07-10

140

Active Flow Control on a S10 Glider Configuration  

Microsoft Academic Search

\\u000a This paper presents active flow control results using periodic excitation on a wing section with a plain flap of a Stemme S10 glider configuration. The experiments were carried out in a closed loop wind tunnel at a Reynolds number of Rec=1.75·106Re_c=1.75\\\\cdot 10^6. A periodic pulsating jet, introduced from the suction side of the flap near the separation area, was used

Thomas Grund; Wolfgang Nitsche

141

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

142

Vorticity of Subsurface Flows of Emerging and Decaying Active Regions  

NASA Astrophysics Data System (ADS)

We study the temporal variation of the vorticity of subsurface flows of 828 active regions and 977 quiet regions. The vorticity of these flows is derived from measured subsurface velocities. The horizontal flows are determined by analyzing high-resolution Global Oscillation Network Group Doppler data with ring-diagram analysis covering a range of depths from the surface to about 16 Mm. The vertical velocity component is derived from the divergence of the measured horizontal flows using mass conservation. We determine the change in unsigned magnetic flux density during the disk passage of each active region using Michelson Doppler Imager (MDI) magnetograms binned to the ring-diagram grid with centers spaced by 7.5° ranging ± 52.5° in latitude and central meridian distance with an effective diameter of 15° after apodization. We then sort the data by their flux change from decaying to emerging flux and divide the data into five subsets of equal size. We find that the vorticity of subsurface flows increases during flux emergence and decreases when active regions decay. For flux emergence, the absolute values of the zonal and meridional vorticity components show the most coherent variation with activity, while for flux decrease the strongest signature is in the absolute values of the meridional and vertical vorticity components. The temporal variation of the enstrophy (residual vorticity squared) is thus a good indicator for either flux increase or decrease. There are some indications that the increase in vorticity during flux emergence happens about a day later at depths below about 8 Mm compared to layers shallower than about 4 Mm. This timing difference might imply that the vorticity signal analyzed here is caused by the interaction between magnetic flux and turbulent flows near the solar surface. There are also hints that the vorticity decrease during flux decay begins about a day earlier at layers deeper than about 8 Mm compared to shallower ones. However, the timing difference between the change at different depths is comparable to the time step of the analysis.

Komm, R.; Howe, R.; Hill, F.

2012-04-01

143

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

144

Energy Activities for the Primary Classroom. Revised.  

ERIC Educational Resources Information Center

|An energy education program at the primary level should help students to understand the nature and importance of energy, consider different energy sources, learn about energy conservation, prepare for energy related careers, and become energy conscious in other career fields. The activities charts, readings, and experiments provided in this…

Tierney, Blue, Comp.

145

Density dependence of symmetry energy and collective transverse in-plane flow  

Microsoft Academic Search

We study the sensitivity of the collective transverse in-plane flow to the symmetry energy and its density dependence at Fermi energies and higher incident energies. We find that collective transverse in-plane flow is sensitive to the symmetry energy and its density dependence at Fermi energies whereas it shows insensitivity at higher incident energies.

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

2011-01-01

146

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

147

An Accurate Method for Measuring Activation Energy  

Microsoft Academic Search

In this letter, we present an accurate method for the measurement of activation energy. This method combined the excitation power dependent photoluminescence and temperature dependent photoluminescence together to obtain activation energy. We found with increasing temperature, there is a step transition from one emission mechanism to another. This step transition gives us an accurate measurement of activation energy. Using this

Xiang-Bai Chen; Jesse Huso; John L. Morrison; Leah Bergman

2005-01-01

148

Active flow control for a blunt trailing edge profiled body  

NASA Astrophysics Data System (ADS)

Flow in the wake of nominally two-dimensional bluff bodies is dominated by vortex shedding, beyond a very small threshold Reynolds number. Vortex shedding poses challenges in the design of structures, due to its adverse effects such as cyclic aerodynamic loads and fatigue. The wake vortices are often accompanied by large- and small-scale secondary instabilities, which manifest as dislocations in the primary wake vortices, and/or pairs of counter-rotating streamwise vortices, depending on the dominant instability mode(s), which in turn depends on the profile geometry and Reynolds number. The secondary instabilities interact with the wake vortices through several mechanisms. Therefore, manipulation of the secondary instabilities can be used as a means to alter the wake vortices, in order to reduce their adverse effects. In the present study, flow in the wake of a blunt trailing edge profiled body, composed of an elliptical leading edge and a rectangular trailing edge, has been studied at Reynolds numbers ranging from Re(d) = 500 to 2150 where d is thickness of the body, to identify the secondary instabilities. Various tools, including numerical simulations, Laser Induced Fluorescence (LIF), and Particle Image Velocimetry (PIV) have been used for this study. Proper Orthogonal Decomposition (POD) has been applied to analyze the velocity field data. The results indicate the existence of small-scale instabilities with a spanwise wavelength of 2.0d to 2.5d in the near wake. The mechanism of the instability is similar to the Mode-A instability of a circular cylinder; however, it displays features that are specific to the blunt trailing edge profiled body. An active three-dimensional flow control mechanism based on the small-scale instabilities has been designed and evaluated. The mechanism comprises a series of trailing edge injection ports, with a spanwise spacing equal to the wavelength of the small-scale instabilities. Following preliminary evaluation of the control mechanism through numerical simulations, and experimental study of the effect of injection flow rate, extensive PIV experiments have been conducted to investigate the effectiveness of the flow control mechanism, and its effects on the wake flow structure, at Reynolds numbers ranging from Re(d ) = 700 to 1980. Measurements have been carried out at multiple spanwise locations, to establish a comprehensive image of the effect of the flow control mechanism on parameters such as drag force, wake width, and formation length. POD analysis and frequency spectrums are used to describe the process by which the mechanism affects the wake parameters and drag force. The results indicate that the flow control mechanism is able to reduce drag force by 10%. It is also shown that the best effectiveness in terms of suppression of the drag component resulting from velocity fluctuations is achieved when the flow control actuation wavelength closely matches the wavelength of the small-scale instabilities. KEYWORDS: Blunt Trailing Edge Profiled Body, Vortex Shedding, Wake Instability, Streamwise Vortex, Flow Control, Drag Reduction, Particle Image Velocimetry (PIV), Laser Induced Fluorescence (LIF), Flow Visualization, Numerical Simulation

Naghib Lahouti, Arash

149

Observations of shear flows in high-energy-density plasmas  

NASA Astrophysics Data System (ADS)

The research discussed in this thesis represents work toward the demonstration of experimental designs for creating a Kelvin-Helmholtz (KH) unstable shear layer in a high-energy-density (HED) plasma. Such plasmas are formed by irradiating materials with several kilo-Joules of laser light over a few nanoseconds, and are defined as having an internal pressure greater than one-million atmospheres. Similar plasmas exist in laboratory fusion experiments and in the astrophysical environment. The KH instability is a fundamental fluid instability that arises when strong velocity gradients exist at the interface between two fluids. The KH instability is important because it drives the mixing of fluids and initiates the transition to turbulence in the flow. Until now, the evolution of the KH instability has remained relatively unexplored in the HED regime This thesis presents the observations and analysis of two novel experiments carried out using two separate laser facilities. The first experiment used 1.4 kJ from the Nike laser to generate a supersonic flow of Al plasma over a low-density, rippled foam surface. The Al flow interacted with the foam and created distinct features that resulted from compressible effects. In this experiment there is little evidence of the KH instability. Nevertheless, this experimental design has perhaps pioneered a new method for generating a supersonic shear flow that has the potential to produce the KH instability if more laser energy is applied. The second experiment was performed on the Omega laser. In this case 4.3 kJ of laser energy drove a blast wave along a rippled foam/plastic interface. In response to the vorticity deposited and the shear flow established by the blast wave, the interface rolls up into large vorticies characteristic of the KH instability. The Omega experiment was the first HED experiment to capture the evolution of the KH instability.

Harding, Eric C.

150

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

151

K.E.E.P. - Kentucky's Energy Education Program Activities for the Classroom, 7-12.  

ERIC Educational Resources Information Center

|Seventy-four multidisciplinary activities for grades seven through twelve are contained in this revised edition of energy education lessons for Kentucky students. Section I helps students understand energy and the current crisis by studying laws which govern energy flow and using examples of how these laws illustrate stable energy utilization…

Theiss, Nancy Stearns, Ed.; And Others

152

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.

153

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).

Farrell-Poe, Kitt

154

Structure of urban movements: polycentric activity and entangled hierarchical flows.  

PubMed

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

2011-01-07

155

Numerical approach to plug-flow activated sludge reactor kinetics.  

PubMed

In this study, general relationships applicable to a wide variety of microbial-mediated treatment processes are developed using a number of continuous-flow stirred tank reactors-in-series. Simultaneous equations resulting from mass balance on substrate and biomass are solved numerically taking the longitudinal biomass gradient into account. A relationship between substrate and biomass concentrations is developed as a function of hydraulic residence time. Monod kinetics and mathematical models of reactors-in-series are used to represent the actual conditions resulting from varying degrees of axial dispersion and wastewater quality. Dimensionless quantities are used to reduce the number of parameters to be taken into account. Computer techniques are applied to express the results generally. By means of the numerical approach, the variation of the ratio between the hydraulic residence time of a given reactor and that of an equivalent plug-flow tank with the same inlet and outlet conditions is investigated. Results are expressed in the form of graphs to characterize the plug-flow activated sludge systems and to provide a basis of design. Experimental data reported in the literature are also evaluated to demonstrate the cases where the existing classical solution to the problem differs from the actual results obtained from the computer program and the design graphs given. PMID:10821939

Muslu, Y

2000-07-01

156

Bidirectional control system for energy flow in solar powered flywheel  

SciTech Connect

An energy supply system is described for a spacecraft for supplying energy to at least one spacecraft load, the system comprising: a flywheel; an electric motor connected to the flywheel for selectively supplying electrical power to the spacecraft load; solar energy conversion means for receiving solar energy and for converting the received solar energy into an output voltage for supply to the spacecraft load; and electrical control means for (1) sensing the spacecraft load voltage, and feeding back the sensed voltage to regulate the voltage supplied to the spacecraft load when the spacecraft load voltage changes, and for (2) comparing the output voltage from the solar energy conversion means with a threshold voltage and, when the threshold voltage is exceeded, activating a speed control loop including the motor so as to accelerate the flywheel to a constant speed to thereby convert the electrical energy supplied from the solar energy conversion means into mechanical energy. When the threshold voltage is not exceeded, the speed control loop is deactivated and a voltage control loop is activated for controlling the amount of mechanical energy from the flywheel which is converted into an electrical energy output from the motor for supply to the spacecraft load in according with the sensed load voltage.

Nola, F.J.

1987-03-10

157

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

2010-04-08

158

Model estimation of energy flow in Oregon coastal seabird populations  

USGS Publications Warehouse

A computer simulation model was used to explore the patterns and magnitudes of population density changes and population energy demands in Oregon populations of Sooty Shear-waters, Leach?s Storm-Petrels, Brandt?s Cormorants, and Common Murres. The species differ in seasonal distribution and abundance, with shearwaters attaining high densities during their migratory movements through Oregon waters, and murres exhibiting the greatest seasonal stability in population numbers. On a unit area basis, annual energy flow is greatest through murre and cormorant populations. However, because shearwaters occupy a larger area during their transit, they dominate the total energy flow through the four-species seabird ?community.?.....Consumption of various prey types is estimated by coupling model output of energy demands with information on dietary habits. This analysis suggests that murres annually consume nearly twice as many herring as any other prey and consume approximately equal quantities of anchovy, smelt, cod, and rockfish. Cormorants consume a relatively small quantity of bottom-dwelling fish, while stormpetrels take roughly equal quantities of euphausiids and hydrozoans. Anchovies account for 43% of the 62,506 metric tons of prey the four species are estimated to consume annually; 86% of this anchovy consumption is by shearwaters. The consumption of pelagic fishes by these four populations within the neritic zone may represent as much as 22% of the annual production of these fish.

Wiens, J.A.; Scott, J.M.

1976-01-01

159

Using streamlines to visualize acoustic energy flow across boundaries.  

PubMed

For spherical waves that radiate from a point source in a homogeneous fluid and propagate across a plane boundary into a dissimilar homogeneous fluid, the acoustic field may differ significantly from the geometric acoustic approximation if either the source or receiver is near the interface (in acoustic wavelengths) or if the stationary phase path is near the critical angle. In such cases, the entire acoustic field must be considered, including inhomogeneous waves associated with diffraction (i.e., those components that vanish with increasing frequency). The energy flow from a continuous-wave monopole point source across the boundary is visualized by tracing acoustic streamlines: those curves whose tangent at every point is parallel to the local acoustic intensity vector, averaged over a wave cycle. It is seen that the acoustic energy flow is not always in line with the "Snell's law" or stationary phase path. Also, plots of acoustic energy streamlines do not display unusual behavior in the vicinity of the critical angle. Finally, it is shown that there exists a law of refraction of acoustic energy streamlines at boundaries with density discontinuities analogous to Snell's law of refraction of ray paths across sound speed discontinuities. Examples include water-to-seabed transmission and water-to-air transmission. PMID:18646954

Chapman, David M F

2008-07-01

160

PAK signaling regulates oxidant-dependent NF-?B activation by flow  

PubMed Central

Disturbed blood flow promotes atherosclerosis mainly by inducing inflammatory gene expression in endothelial cells. Flow stimulates the proinflammatory transcription factor NF-?B through integrin- and Rac-dependent production of reactive oxygen species (ROS). Previous work demonstrated that NF-?B activation by flow is matrix-specific, occurring in cells on fibronectin but not collagen. Activation of p21-activated kinase (PAK) followed the same matrix-dependent pattern. We now show that inhibiting PAK in cells on fibronectin blocked NF-?B activation by both laminar and oscillatory flow in vitro and at sites of disturbed flow in vivo. Constitutively active PAK rescued flow-induced NF-?B activation in cells on collagen. Surprisingly, PAK was not required for flow-induced ROS production. Instead, PAK modulated the ability of H2O2 to activate the NF-?B pathway. These data demonstrate that PAK controls NF-?B activation by modulating cells’ sensitivity to ROS.

Orr, A. Wayne; Hahn, Cornelia; Blackman, Brett R.; Schwartz, Martin Alexander

2009-01-01

161

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.

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

2012-01-01

162

Cellular Links between Neuronal Activity and Energy Homeostasis.  

PubMed

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

2012-03-20

163

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

164

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

165

Measurements of sideward flow around the balance energy  

NASA Astrophysics Data System (ADS)

Sideward flow values have been determined with the INDRA multidetector for Ar+Ni, Ni+Ni, and Xe+Sn systems studied at GANIL in the 30A to 100A MeV incident energy range. The balance energies found for Ar+Ni and Ni+Ni systems are in agreement with previous experimental results and theoretical calculations. Negative sideward flow values have been measured. The possible origins of such negative values are discussed. They could result from a more important contribution of evaporated particles with respect to the contribution of promptly emitted particles at midrapidity. But effects induced by the methods used to reconstruct the reaction plane cannot be totally excluded. Complete tests of these methods are presented and the origins of the ``autocorrelation'' effect have been traced back. For heavy fragments, the observed negative flow values seem to be mainly due to the reaction plane reconstruction methods. For light charged particles, these negative values could result from the dynamics of the collisions and from the reaction plane reconstruction methods as well. These effects have to be taken into account when comparisons with theoretical calculations are done.

Cussol, D.; Lefort, T.; Péter, J.; Auger, G.; Bacri, Ch. O.; Bocage, F.; Borderie, B.; Bougault, R.; Brou, R.; Buchet, Ph.; Charvet, J. L.; Chbihi, A.; Colin, J.; Dayras, R.; Demeyer, A.; Doré, D.; Durand, D.; Eudes, P.; de Filippo, E.; Frankland, J. D.; Galichet, E.; Genouin-Duhamel, E.; Gerlic, E.; Germain, M.; Gourio, D.; Guinet, D.; Lautesse, P.; Laville, J. L.; Lecolley, J. F.; Le Fèvre, A.; Legrain, R.; Le Neindre, N.; Lopez, O.; Louvel, M.; Maskay, A. M.; Nalpas, L.; N'Guyen, A. D.; Parlog, M.; Plagnol, E.; Politi, G.; Rahmani, A.; Reposeur, T.; Rivet, M. F.; Rosato, E.; Saint-Laurent, F.; Salou, S.; Steckmeyer, J. C.; Stern, M.; Tabacaru, G.; Tamain, B.; Tassan-Got, L.; Tirel, O.; Vient, E.; Volant, C.; Wieleczko, J. P.

2002-04-01

166

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

167

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

168

Energy Activities for the Classroom: Volume II.  

ERIC Educational Resources Information Center

|This resource book contains descriptions of over 100 classroom activities designed to illustrate concepts relating to energy, its production, characteristics, use, and conservations. Each activity integrates the energy lesson into a concept that relates to one or more subject areas common to public school curricula. Many of the activities

Coon, Herbert L.; Bowman, Mary Lynne

169

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

170

An active piezoelectric energy extraction method for pressure energy harvesting  

Microsoft Academic Search

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

M Deterre; E Lefeuvre; E Dufour-Gergam

2012-01-01

171

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

PubMed Central

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 NG-monomethyl-l-arginine attenuated but did not completely abolish the effects of flow.

Gashev, Anatoliy A; Davis, Michael J; Zawieja, David C

2002-01-01

172

Single mode heat rectifier: controlling energy flow between electronic conductors.  

PubMed

We study heat transfer between conductors, mediated by the excitation of a monomodal harmonic oscillator. Using a simple model, we show that the onset of rectification in the system is directly related to the nonlinearity of the electron gas dispersion relation. When the metals have a strictly linear dispersion relation, a Landauer-type expression for the thermal current holds, symmetric with respect to the temperature difference. Rectification becomes prominent when deviations from linear dispersion exist, and the fermionic model cannot be mapped into a harmonic bosonized representation. The effects described here are relevant for understanding radiative heat transfer and vibrational energy flow in electrically insulating molecular junctions. PMID:18352208

Segal, Dvira

2008-03-13

173

Velocity and Energy Relaxation in Two-Phase Flows  

Microsoft Academic Search

In the present study we investigate analytically the process of velocity and\\u000aenergy relaxation in two-phase flows. We begin our exposition by considering\\u000athe so-called six equations two-phase model [Ishii1975, Rovarch2006]. This\\u000amodel assumes each phase to possess its own velocity and energy variables.\\u000aDespite recent advances, the six equations model remains computationally\\u000aexpensive for many practical applications. Moreover, its

Yannick Meyapin; Denys Dutykh; Marguerite Gisclon

2010-01-01

174

On the kinetic energy of the divergent and nondivergent flow in the atmosphere  

Microsoft Academic Search

The kinetic energy of horizontal flow in a hydrostatic atmosphere is divided into the kinetic energies of its divergent and nondivergent compounds. The law of conversion between these two energies for large-scale flows in the atmosphere is derived and discussed with balanced and unbalanced models of circulations in the atmosphere. It is shown that the total potential energy is converted

T. C. Chen

1975-01-01

175

Autonomous Motility of Active Filaments due to Spontaneous Flow-Symmetry Breaking  

NASA Astrophysics Data System (ADS)

We simulate the nonlocal Stokesian hydrodynamics of an elastic filament which is active due a permanent distribution of stresslets along its contour. A bending instability of an initially straight filament spontaneously breaks flow symmetry and leads to autonomous filament motion which, depending on conformational symmetry, can be translational or rotational. At high ratios of activity to elasticity, the linear instability develops into nonlinear fluctuating states with large amplitude deformations. The dynamics of these states can be qualitatively understood as a superposition of translational and rotational motion associated with filament conformational modes of opposite symmetry. Our results can be tested in molecular-motor filament mixtures, synthetic chains of autocatalytic particles, or other linearly connected systems where chemical energy is converted to mechanical energy in a fluid environment.

Jayaraman, Gayathri; Ramachandran, Sanoop; Ghose, Somdeb; Laskar, Abhrajit; Bhamla, M. Saad; Kumar, P. B. Sunil; Adhikari, R.

2012-10-01

176

Energy Analysis of Flow Induced Harmonic Motion in Blood Vessel Walls  

Microsoft Academic Search

Energy is transferred between the flowing blood and the vessel walls during pulsatile blood flow (a normal pulse cycle) resulting in storage and dissipation of elastic energy. This allows the elastic and muscular arteries to act as an auxiliary pump to propel the blood fluid forward during systole and maintain a basal blood pressure during diastole. The pulsatile flow pattern

Istvan Horvath; David J. Foran; Frederick H. Silver

2005-01-01

177

Limits of tidal energy dissipation by fluid flow in subsea formations  

NASA Astrophysics Data System (ADS)

Tidal loading causes fluid flow through permeable seafloor and between regions of contrasting elastic properties or porosity within subsea formations. We examine theoretically the dissipation of energy by these flows and its global significance as a mechanism for tidal energy dissipation. Expressions are given for energy dissipation rates in layered formations due to vertical flow caused by tidal loading, but the results can be used to constrain dissipation by other flow patterns. We consider flow near the seafloor, in gas-bearing sediments, and in highly fractured permeable igneous crust. Energy dissipation by the first two mechanisms is negligibly small globally, although it may be locally significant under extreme conditions. Under favourable conditions, flow in fractured crust may have greater energy dissipation, but the total amount is limited by the thickness of the permeable layer. Based on our current understanding of subsea hydrogeology, tidally induced flow in subsea formations appears to make little contribution to the observed global tidal energy dissipation.

Wang, Kelin; van der Kamp, Garth; Davis, Earl E.

1999-12-01

178

Flow-activated ion channels in vascular endothelium  

Microsoft Academic Search

The ability of vascular endothelial, cells (ECs) to respond to fluid mechanical forces associated with blood flow is essential\\u000a for flow-mediated vasoregulation and arterial wall remodeling. Abnormalities in endothelial responses to flow also play a\\u000a role in the development of atherosclerosis. Although our understanding of the endothelial signaling pathways stimulated by\\u000a flow has greatly increased over the past two decades,

Mamta Gautam; Andrea Gojova; Abdul I. Barakat

2006-01-01

179

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

180

Comparison of two activity analyses : context-sensitive flow-insensitive vs. context-insensitive flow-sensitive.  

SciTech Connect

Automatic differentiation (AD) is a family of techniques to generate derivative code from a mathematical model expressed in a programming language. AD computes partial derivatives for each operation in the input code and combines them to produce the desired derivative by applying the chain rule. Activity analysis is a compiler analysis used to find active variables in automatic differentiation. By lifting the burden of computing partial derivatives for passive variables, activity analysis can reduce the memory requirement and run time of the generated derivative code. This paper compares a new context-sensitive flow-insensitive (CSFI) activity analysis with an existing context-insensitive flow-sensitive (CIFS) activity analysis in terms of execution time and the quality of the analysis results. Our experiments with eight benchmarks show that the new CSFI activity analysis runs up to 583 times faster and overestimates up to 18.5 times fewer active variables than does the existing CIFS activity analysis.

Shin, J.; Hovland, P. D.; Mathematics and Computer Science

2007-01-01

181

Drag reduction of motor vehicles by active flow control using the Coanda effect  

NASA Astrophysics Data System (ADS)

A test facility has been constructed to realistically simulate the flow around a two dimensional car shaped body in a wind tunnel. A moving belt simulator has been employed to generate the relative motion between model and ground. In a first step, the aerodynamic coefficients cL and cD of the model are determined using static pressure and force measurements. LDA-measurements behind the model show the large vortex and turbulence structures of the near and far wake. In a second step, the ambient flow around the model is modified by way of an active flow control which uses the Coanda effect, whereby the base-pressure increases by nearly 50% and the total drag can be reduced by 10%. The recirculating region is completely eliminated. The current work reveals the fundamental physical phenomena of the new method by observing the pressure forces on the model surface as well as the time averaged velocities and turbulence distributions for the near and far wake. A theory resting on this empirical information is developed and provides information about the effectiveness of the blowing method. For this, momentum and energy equations were applied to the flow around the vehicle to enable a validation of the theoretical results using experimental values.

Geropp, D.; Odenthal, H.-J.

182

Energy flow models for the estimation of technical losses in distribution network  

NASA Astrophysics Data System (ADS)

This paper presents energy flow models developed to estimate technical losses in distribution network. Energy flow models applied in this paper is based on input energy and peak demand of distribution network, feeder length and peak demand, transformer loading capacity, and load factor. Two case studies, an urban distribution network and a rural distribution network are used to illustrate application of the energy flow models. Results on technical losses obtained for the two distribution networks are consistent and comparable to network of similar types and characteristics. Hence, the energy flow models are suitable for practical application.

Au, Mau Teng; Hooi Tan, Chin

2013-06-01

183

Energy resources' utilization in organic and conventional vineyards: Energy flow, greenhouse gas emissions and biofuel production  

Microsoft Academic Search

An energy analysis, in conventional and organic vineyards, combined with ethanol production and greenhouse gas emissions, is useful in evaluating present situation and deciding best management strategies. The objective of this study was to evaluate the differences in the energy flow between organic and conventional vineyards in three locations, to calculate CO2, CH4 and N2O-emissions based on the used fossil

Stefanos E. Kavargiris; Andreas P. Mamolos; Constantinos A. Tsatsarelis; Anna E. Nikolaidou; Kiriaki L. Kalburtji

2009-01-01

184

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

185

Comparison of Boundary Mapping Efficiency of Gradient Vector Flow Active Contours and their Variants on Chromosome Spread Images  

Microsoft Academic Search

This study compares the boundary mapping efficiency of curve evolution method on chromosome spread images. The curve evolution methods chosen for comparison gradient vector flow active contours, generalized gradient vector flow active contours, discrete cosine transform based gradient vector flow active contours and discrete cosine transform based generalized gradient vector flow active contours. Chromosome spread images were characterized by chromosome

A. Prabhu Britto; G. Ravindran

2005-01-01

186

Observations of subsonic and supersonic shear flows in laser driven high-energy-density plasmas  

NASA Astrophysics Data System (ADS)

Shear layers containing strong velocity gradients appear in many high-energy-density (HED) systems and play important roles in mixing and the transition to turbulence. Yet few laboratory experiments have been carried out to study their detailed evolution in this extreme environment where plasmas are compressible, actively ionizing, often involve strong shock waves and have complex material properties. Many shear flows produce the Kelvin-Helmholtz (KH) instability, which initiates the mixing at a fluid interface. We present results from two dedicated shear flow experiments that produced overall subsonic and supersonic flows using novel target designs. In the subsonic case, the Omega laser was used to drive a blast wave along a rippled interface between plastic and foam, shocking both the materials to produce two fluids separated by a sharp shear layer. The interface subsequently rolled-upped into large KH vortices that were accompanied by bubble-like structures of unknown origin. This was the first time the evolution of a well-resolved KH instability was observed in a HED plasma in the laboratory. We have analyzed the properties and dynamics of the plasma based on the data and fundamental models, without resorting to simulated values. In the second, supersonic experiment the Nike laser was used to drive a supersonic flow of Al plasma along a rippled, low-density foam surface. Here again the flowing plasma drove a shock into the second material, so that two fluids were separated by a shear layer. In contrast to the subsonic case, the flow developed shocks around the ripples in response to the supersonic flow of Al. Collaborators: R.P. Drake, O.A. Hurricane, J.F. Hansen, Y. Aglitskiy, T. Plewa, B.A. Remington, H.F. Robey, J.L. Weaver, A.L. Velikovich, R.S. Gillespie, M.J. Bono, M.J. Grosskopf, C.C. Kuranz, A. Visco.

Harding, E. C.

2009-11-01

187

New statistics for estimating the bulk rheology of active lava flows: Puu Oo examples  

Microsoft Academic Search

Downstream changes in lava rheology due to cooling, crystallization, and vesiculation have a strong influence on the final length and morphology of a lava flow. Three statistics are proposed to estimate the change in lava rheology with distance along the path of an active flow. These statistics correspond to three separate models of the volumetric flow rate dependence on the

S. M. Baloga; L. S. Glaze; J. A. Crisp; S. A. Stockman

1998-01-01

188

Horizontal Flows in the Photosphere and Subphotosphere of Two Active Regions  

NASA Astrophysics Data System (ADS)

We compare horizontal flow fields in the photosphere and in the subphotosphere (a layer 0.5 Mm below the photosphere) in two solar active regions: AR 11084 and AR 11158. AR 11084 is a mature, simple active region without significant flaring activity, and AR 11158 is a multipolar, complex active region with magnetic flux emerging during the period studied. Flows in the photosphere are derived by applying the Differential Affine Velocity Estimator for Vector Magnetograms (DAVE4VM) on HMI-observed vector magnetic fields, and the subphotospheric flows are inferred by time-distance helioseismology using HMI-observed Dopplergrams. Similar flow patterns are found for both layers for AR 11084: inward flows in the sunspot umbra and outward flows surrounding the sunspot. The boundary between the inward and outward flows, which is slightly different in the photosphere and the subphotosphere, is within the sunspot penumbra. The area having inward flows in the subphotosphere is larger than that in the photosphere. For AR 11158, flows in these two layers show great similarities in some areas and significant differences in other areas. Both layers exhibit consistent outward flows in the areas surrounding sunspots. On the other hand, most well-documented flux-emergence-related flow features seen in the photosphere do not have counterparts in the subphotosphere. This implies that the horizontal flows caused by flux emergence do not extend deeply into the subsurface.

Liu, Yang; Zhao, Junwei; Schuck, P. W.

2013-10-01

189

Transverse energy flows in vectorial fields of paraxial light beams  

NASA Astrophysics Data System (ADS)

A general study of transverse energy flows (TEF) as physically meaningful and informative characteristics of paraxial light beams' spatial structure is presented. The total TEF can be decomposed into the spin and orbital contributions giving rise to the spin and orbital angular momentums, correspondingly. Definitions and properties of these constituents are discussed in relation with the optical field representation through linear and circular orthogonal polarization bases. An analysis of TEFs near singular points has been carried out. General discussion of the evolution of the optical field singularities is presented. Possible mechanical action of light beams associated with the TEF is studied on the example of an absorptive medium described by the Drude-Lorentz model.

Bekshaev, Aleksandr; Soskin, Marat

2007-07-01

190

Azimuthal energy flow in deep inelastic neutrino scattering  

SciTech Connect

Gluon emission and the transverse momentum (p/sub t/) of partons confined in nucleons were studied using deep-inelastic charged-current neutrino-nucleon interactions. For this analysis we use the flow of hadronic energy in the azimuthal direction around the momentum transfer referenced from the neutrino-muon scattering plane. A five standard deviation asymmetry was found. Analysis of this asymmetry indicates a (p/sub t/) of 0.35 +- 0.12 GeV/c if QCD corrections are included, and 0.56 +- 0.05 GeV/c if they are excluded. Some evidence was also observed for x dependence in p/sub t/. Data were taken at Fermilab in 1982 using a 200 ton (fiducial mass) fine grained calorimeter and a dichromatic neutrino beam.

Mukherjee, A.; Bofill, J.; Busza, W.; Eldridge, T.F.; Friedman, J.I.; Fuess, S.; Goodman, M.C.; Kendall, H.W.; Lyons, T.F.; Magahiz, R.A.

1986-06-12

191

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.

192

Active control of flow induced resonance in continuous corrugated tubes  

NASA Astrophysics Data System (ADS)

Wind tunnel experiments were conducted to study sound generation from corrugate tubes. Hot-wire and microphone measurements were used to determine the response of the following tube geometries to flow excitation: fully corrugated tube, tube with two corrugations, tube with one corrugation only, and tube with no corrugations at all. For the tube with at least two bumps, it was found that the acoustic output peaks when there is an integer number (K) of vortical structures in the cavities between two bumps. The highest peak corresponds to K=1. Some experiments were undertaken to suppress or at least minimize the sound level. One method which significantly reduced the sound intensity consisted of cutting a narrow strip off the tube along the whole length and replacing it with a smooth strip. This is equivalent to cutting a piece off each bump. A more active method of control consisted of forcing the first bump or cavity by using a set of twelve small speakers positioned in a circle around the tube. This technique only allowed the elimination of the lower sound levels, whereas the K=1 mode was only partially reduced.

Gharib, Morteza

1993-05-01

193

Energy and Energy Conservation Activities for High School Students.  

ERIC Educational Resources Information Center

This manual contains fifteen energy activities suitable for high school physical and environmental science and mathematics classrooms. The activities are independent, each having its own objectives, introduction, and background information. A special section of each activity is written for the instructor and contains limits, sample data, and…

Bottinelli, Charles A., Ed.; Dow, John O., Ed.

194

Multidimensional Multiscale Dynamics of High-Energy Astrophysical Flows  

NASA Astrophysics Data System (ADS)

Astrophysical flows have an enormous dynamic range of relevant length scales. The physics occurring on the smallest scales often influences the physics of the largest scales, and vice versa. I present a detailed study of the multiscale and multidimensional behavior of three high-energy astrophysical flows: jet-driven supernovae, massive black hole accretion, and current-driven instabilities in gamma-ray burst external shocks. Both theory and observations of core-collapse supernovae indicate these events are not spherically-symmetric; however, the observations are often modeled assuming a spherically-symmetric explosion. I present an in-depth exploration of the effects of aspherical explosions on the observational characteristics of supernovae. This is accomplished in large part by high-resolution, multidimensional numerical simulations of jet-driven supernovae. The existence of supermassive black holes in the centers of most large galaxies is a well-established fact in obervational astronomy. How such black holes came to be so massive, however, is not well established. In this work, I discuss the implications of radiative feedback and multidimensional behavior on black hole accretion. I show that the accretion rate is drastically reduced relative to the Eddington rate, making it unlikely that stellar mass black holes could grow to supermassive black holes in less than a Hubble time. Finally, I discuss a mechanism by which magnetic field strength could be enhanced behind a gamma-ray burst external shock. This mechanism relies on a current-driven instability that would cause reorganization of the pre-shock plasma into clumps. Once shocked, these clumps generate vorticity in the post-shock plasma and ultimately enhance the magnetic energy via a relativistic dynamo process.

Couch, Sean Michael

2010-05-01

195

Activation-Blood Flow Coupling During Direct Somatosensory Cortical Stimulation in Living Rat Brain  

Microsoft Academic Search

Laser Doppler flowmetry was used to characterize the cortical activation-blood flow coupling due to direct stimulation in somatosensory cortex of rat brain in vivo. Both amplitude and duration of the flow response increased along with the increases in stimulation current. Flow response became to saturate in a high-grade stimulation with the current above 0.3 mA. The flow response also featured

Zhongchi Luo; Helene Benveniste; Mei Yu; Congwu Du

2005-01-01

196

Photoinhibition in Chlamydomonas reinhardtii: Effect on state transition, intersystem energy distribution and Photosystem I cyclic electron flow  

Microsoft Academic Search

The energy distribution, state transitions and photosynthetic electron flow during photoinhibition of Chlamydomonas reinhardtii cells have been studied in vivo using photoacoustics and modulated fluorescence techniques. In cells exposed to 2500 W\\/m2 light at 21 °C for 90 min, 90% of the oxygen evolution activity was lost while photochemical energy storage as expressed by the parameter photochemical loss (P.L.) at

Ora Canaani; Gadi Schuster; Itzhak Ohad

1989-01-01

197

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

198

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

199

Alternative energy activities for young children  

SciTech Connect

Several successful alternative energy activities for children 5 to 10 years old are presented in this paper. Responses of the children are documented and three of their poster drawings for an evening presentation to the parents are included.

Blair, J.

1981-01-01

200

Inquiry Activities for the Energy Crisis  

ERIC Educational Resources Information Center

A unit to be used as a means of assisting students in formalizing their position on the fundamental issues within the energy crisis includes objectives, learning activities, and a resource list. (Author/KM)

Campbell, Lloyd P.

1973-01-01

201

Time-activity budgets and energetics of Dipper Cinclus cinclus are dictated by temporal variability of river flow.  

PubMed

The white-throated Dipper (Cinclus cinclus) is unique among passerine birds by its reliance on diving to achieve energy gain in fast-flowing waters. Consequently, it should have evolved behavioural adaptations allowing responding directly to runoff patterns (one of the assumptions of the Natural Flow Regime Paradigm-NRFP). In this study (October 1998-August 2001), we investigated how behavioural and energy use strategies in Dippers might vary under the natural flow regime of snowmelt-dominated streams in The Pyrénées (France) where natural flow regime is highly seasonal and predictable. We recorded time spent in each of 5 behavioural activities of ringed birds to estimate time-activity budgets and derive time-energy budgets enabling the modelling of daily energy expenditure (DEE). Annual pattern in 'foraging' and 'resting' matched perfectly the annual pattern of the natural regime flow and there was a subtle relationship between water stage and time spent 'diving' the later increasing with rising discharge up to a point where it fell back. Thus, time-activity budgets meet the main prediction of the NRFP. For males and females Dippers, estimates of feeding rates (ratio E(obs)/E(req)=observed rate of energy gain/required foraging rate) and energy stress (M=DEE/Basal Metabolic Rate) also partly matched the NFRP. Maximum value for the ratio E(obs)/E(req) was registered in May whilst M peaked in spring. These ratios indicated that Pyrenean Dippers could face high energy stress during winter but paradoxically none during high snowmelt spates when food is expected to be difficult to obtain in the channel and when individual birds were observed spending ca 75% of the day 'resting'. Annual pattern in DEE did not match the NFRP; two phases were clearly identified, the first between January to June (with oscillating values 240-280 kJ d(-1) ind(-1)) and the second between July and December (200-220 kJ d(-1) ind(-1)). As total energy expenditure was higher during the most constraining season or life cycle, we suggest that energy management by Dippers in Pyrenean mountain streams may fit the 'peak total demand' hypothesis. At this step of the study, it is not possible to tell whether Dippers use an 'energy-minimisation' or an 'energy-maximisation' strategy. PMID:17897855

D'Amico, F; Hémery, G

2007-08-15

202

Effect of local energy supply to a hypersonic flow on the drag of bodies with different nose bluntness  

NASA Astrophysics Data System (ADS)

Parameters of the axisymmetric flow around bodies with different bluntness are compared in the case of constant energy supply to the main hypersonic flow. Flow structures, drag coefficients, and expenditure of energy on overcoming drag are analyzed with the effect of thermal energy on the flow taken into account for different bodies with equal volume.

Borzov, V. Yu.; Rybka, I. V.; Yur'ev, A. S.

1994-11-01

203

Do blind cavefish have behavioral specializations for active flow-sensing?  

Microsoft Academic Search

Blind cavefish use a form of active sensing in which burst-coast swimming motions generate flow signals detected by the lateral\\u000a line. To determine if blind cavefish have evolved behavioral specializations for active flow-sensing, including the ability\\u000a to regulate flow signal production through lateral line feedback, the swimming kinematics of blind and sighted morphs of Astyanax were compared before and after

Delfinn Tan; Paul Patton; Sheryl Coombs

2011-01-01

204

Transcranial laser doppler mapping of activation flow coupling of the rat somatosensory cortex  

Microsoft Academic Search

Signal averaged laser Doppler (LD) through a thinned skull over the rat somatosensory cortex was used to map the spatial and temporal characteristics of activation-flow coupling, the change in regional cerebral blood flow (CBF) due to neuronal activation, in response to electrical forepaw stimulation. The location of maximal changes in amplitude of the LD response was reproducibly recorded at 4–5

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

1998-01-01

205

A Review of UK Wind Energy Activities  

Microsoft Academic Search

Wind energy activities in the UK have so far concentrated on comprehensive studies of system integration aspects and a detailed assessment of offshore wind energy systems. There is particular interest in offshore systems, which could provide a significant proportion of Britain's electricity needs. Many small wind turbines have been built and tested, but the design and construction of large wind

P. J. MUSGROVE

1982-01-01

206

Active Control of Secondary Flow in Engine Inlets.  

National Technical Information Service (NTIS)

As the next generation of unmanned aerial vehicles (UAV) and unmanned combat aerial vehicles (UCAV) are being developed, the need for highly compact inlet diffusers is increasing quickly. In order to design and evaluate such inlets, additional flow proper...

J. P. Sullivan

2002-01-01

207

Active-adaptive Control of Acoustic Resonances in Flows  

Microsoft Academic Search

\\u000a Several fluid flow problems related to propulsion and power generation exhibit strong acoustic resonances. Produced due to\\u000a interactions of the acoustics with other underlying unsteady mechanisms such as unsteady heat-release or shear flow instability,\\u000a these resonances manifest as large and sustained pressure oscillations. In addition to the obvious undesirable effect of high\\u000a ambient noise and acoustic fatigue, these oscillations are

Anuradha M. Annaswamy

208

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

209

Isospin-dependent nucleon-nucleon cross section and symmetry energy: sensitivity towards collective transverse flow  

Microsoft Academic Search

We study the sensitivity of isospin dependence of nucleon-nucleon cross section and symmetry energy on the collective transverse in-plane flow. We find that collective transverse flow in Ca+Ca reactions shows great sensitivity to isospin dependence of nn cross section and symmetry energy.

Sakshi Gautam; Rajeev K. Puri

2011-01-01

210

Process for producing energy from water flowing down a borehole and recovery same  

Microsoft Academic Search

This patent describes a system for producing energy from water flow. It comprises: providing a vertical borehole of sufficient depth to convert liquid water to steam through geothermal energy as the water travels theredown; positioning an internal feed pipe into the borehole; providing an air turbine on the upper end of the feed pipe to allow air flowing into the

Daly

1992-01-01

211

Biodiversity in soil ecosystems: the role of energy flow and community stability  

Microsoft Academic Search

In a series of community food webs from native and agricultural soils, we modeled energetics and stability, and evaluated the role of the various groups of organisms and their interactions in energy flow and community stability. Species were aggregated into functional groups based on their trophic position in the food webs. Energy flow rates among the groups were calculated by

Peter C. de Ruiter; Anje-Margriet Neutel; John C. Moore

1998-01-01

212

Theory of materials and energy flow analysis in ecology and economics  

Microsoft Academic Search

Materials and energy flow analysis (MEFA) has been widely utilized in ecology and economics, occupying unique positions in both disciplines. The various approaches to materials and energy flow analysis in ecology are reviewed, the focus being on the linear network system introduced from input–output economics. After its introduction in the early 1970s, the calculus and system definition for materials and

Sangwon Suh

2005-01-01

213

Theory of materials and energy flow analysis in ecology and economics  

Microsoft Academic Search

Materials and energy flow analysis (MEFA) has been widely utilized in ecology and economics, occupying unique positions in both disciplines. The various approaches to materials and energy flow analysis in ecology are reviewed, the focus being on the linear network system introduced from input-output economics. After its introduction in the early 1970s, the calculus and system definition for materials and

Sangwon Suha

214

Modeling of Nonstationary Flow in the Ramjet Channel with a Distributed Pulse-Periodic Energy Supply  

Microsoft Academic Search

A study has been made of the influence of a pulse-periodic supply of energy that is equal to the energy released in combustion of hydrogen in air on the structure of supersonic flow in a channel of variable cross section, which models the ramjet duct. The flow has been modeled based on two-dimensional nonstationary gas-dynamics equations. Different regimes of flow

V. P. Zamuraev; A. P. Kalinina

2005-01-01

215

Nonstationary flow in a channel with variable cross section under conditions of periodic pulsed energy supply  

NASA Astrophysics Data System (ADS)

The effect of a periodic pulsed supply of energy, equal to that of hydrogen combustion in air, on the structure of a supersonic flow in a channel of variable cross section modeling a ramjet tract has been studied. The flow has been numerically simulated based on two-dimensional gasdynamic equations. Various flow regimes are obtained depending on the configuration of energy supply zones and the excess air ratio in the channel.

Zamuraev, V. P.; Kalinina, A. P.

2007-04-01

216

Active flow management in preparative chromatographic separations: a preliminary investigation into enhanced separation using a curtain flow inlet fitting and segmented flow outlet fitting.  

PubMed

Active flow management in the form of curtain flow sample introduction and segmented outlet flow control has been shown to enable sample to elute through a chromatography column under the principles of the "infinite diameter column". Such an elution process avoids the detrimental effects of the heterogeneity of particle-packed chromatographic columns by injecting the sample directly into the radial core region of the column, thus avoiding wall effects. The process described herein illustrates how the principles of the infinite diameter column can be applied using conventional injection devices suitable for long-term analysis that requires robust protocols. Using this approach, sensitivity in separation was 2.5 times greater than conventional chromatography, yielding a product at twice the concentration. Benefits of curtain flow injection are thus relevant to both preparative-scale and analytical-scale separations. PMID:22228597

Camenzuli, Michelle; Ritchie, Harald J; Ladine, James R; Shalliker, R Andrew

2012-01-09

217

Active separation control of high-Re turbulent separated flow over a wall-mounted hump using RANS, DES, and LES turbulence modeling approaches  

NASA Astrophysics Data System (ADS)

Most practical flows in engineering applications are turbulent, and exhibit separation which is generally undesirable because of its adverse effects on performance and efficiency. Therefore, control of turbulent separated flows has been a topic of significant interest as it can reduce separation losses. Often, flow control work employs passive techniques to manipulate the flow. Passive-flow control does not require any additional energy source to achieve the control, but is accompanied by additional viscous losses. It is more desirable to employ active techniques as these can be turned on and off, depending on the flow control requirement. The primary goal of the present work is to numerically investigate a high Reynolds number turbulent separated flow. It is Case 3 of the 2004 CFD Validation on Synthetic Jets and Turbulent Separation Control Workshop, http://cfdval2004.larc.nasa.gov/case3.html, conducted by NASA for the flow over a wall-mounted hump. Followed by the baseline flow simulation, i.e., without flow control, active flow control will be investigated using both steady suction jet as well as a "synthetic" jet. Use of synthetic jets has gained popularity in recent times for active flow control because of their ability to transfer linear momentum to the flow system without net-mass injection across the boundary in the vicinity of separation. The present work also implements the use of two jets (steady suction and synthetic jets) as have not been previously implemented for this flow model. For the synthetic-jets case, the work also studies the effect of two jets in opposite phase. The secondary goal of this work is to bring together a variety of turbulence models and simulation approaches for one flow problem. Turbulent Couette flow was used as a model flow problem to validate the flow solver and investigate the performance of different turbulence models and approaches. The flow is simulated using steady and unsteady-state three-dimensional Reynolds-Averaged Navier-Stokes (RANS) equations-based turbulence models and three-dimensional time-dependent Detached Eddy Simulation (DES) and Large-Eddy Simulation (LES) methods. Multiple turbulence modeling approaches help to ascertain what models are most appropriate for capturing the physics of this complex separated flow. The various turbulence modeling cases are simulated with the same grid and solution methodology, and the turbulence models' equations are solved with the same numerical method. This ensures that the variances amongst the results obtained with different models are exclusively due to use of the different turbulence models, and indeed enable assessment of the performance of these models with respect to one another. The results will help us better decide what models to choose for flows with adverse pressure gradients, flow separation and control of separated flows. Validation work using Turbulent Couette flow demonstrates that, for LES, a fine enough grid is required throughout the computational domain and not just near the wall, to capture the turbulent flow structures and flow physics. For the flow over the wall-mounted hump, the simulation results agree well with experiment. Significant computational-resources savings was realized by using an analytical exit velocity profile for the active flow control jets, instead of simulating the entire flow-control manifold without sacrificing the quality of the work. Results compared with experimental values were surface pressure coefficient, skin friction coefficient, mean velocity profiles, Reynolds stresses and flow reattachment locations. Simulation results show some degree of variation with experimental results in the separated flow region. The steady-suction active control was able to reduce the reattachment length the most. The region of negative streamwise velocity was the smallest in the active flow control with steady suction. The multiple jets cases, with steady suction and synthetic jets, were able to reduce the length of separation bubble in comparison to the corresponding single jet cases. Th

Gan, Subhadeep

218

Variational bounds on energy dissipation in incompressible flows. III. Convection  

SciTech Connect

Building on a method of analysis for the Navier-Stokes equations introduced by Hopf [Math. Ann. {bold 117}, 764 (1941)], a variational principle for upper bounds on the largest possible time averaged convective heat flux is derived from the Boussinesq equations of motion. When supplied with appropriate test background fields satisfying a spectral constraint, reminiscent of an energy stability condition, the variational formulation produces rigorous upper bounds on the Nusselt number (Nu) as a function of the Rayleigh number (Ra). For the case of vertical heat convection between parallel plates in the absence of sidewalls, a simplified (but rigorous) formulation of the optimization problem yields the large Rayleigh number bound Nu{le}0.167 Ra{sup 1/2}{minus}1. Nonlinear Euler-Lagrange equations for the optimal background fields are also derived, which allow us to make contact with the upper bound theory of Howard [J. Fluid Mech. {bold 17}, 405 (1963)] for statistically stationary flows. The structure of solutions of the Euler-Lagrange equations are elucidated from the geometry of the variational constraints, which sheds light on Busse{close_quote}s [J. Fluid Mech. {bold 37}, 457 (1969)] asymptotic analysis of general solutions to Howard{close_quote}s Euler-Lagrange equations. The results of our analysis are discussed in the context of theory, recent experiments, and direct numerical simulations. {copyright} {ital 1996 The American Physical Society.}

Doering, C.R. [Center for Nonlinear Studies, MS-B258, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States); Constantin, P. [Department of Mathematics, University of Chicago, Chicago, Illinois 60637 (United States)

1996-06-01

219

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

220

High Pulsatility Flow Induces Acute Endothelial Inflammation through Overpolarizing Cells to Activate NF-?B.  

PubMed

Large artery stiffening and small artery inflammation are both well-known pathological features of pulmonary and systemic hypertension, but the relationship between them has been seldom explored. We previously demonstrated that stiffening-induced high pulsatility flow stimulated a pro-inflammatory response in distal pulmonary artery endothelial cells (PAEC). Herein, we hypothesized that high pulsatility flow activated PAEC pro-inflammatory responses are mediated through cell structural remodeling and cytoskeletal regulation of NF-?B translocation. To test this hypothesis, cells were exposed to low and high pulsatility flows with the same mean physiological flow shear stress. Results showed that unidirectional, high pulsatility flow led to continuous, high-level NF-?B activation, whereas low pulsatility flow induced only transient, minor NF-?B activation. Compared to cell shape under the static condition, low pulsatility flow induced cell elongation with a polarity index of 1.7, while high pulsatility flow further increased the cell polarity index to a value greater than 3. To explore the roles of cytoskeletal proteins in transducing high flow pulsatility into NF-?B activation, PAECs were treated with drugs that reduce the synthesis-breakdown dynamics of F-actin or microtubules (cytochalasin D, phalloidin, nocodazole, and taxol) prior to flow. Results showed that these pre-treatments suppressed NF-?B activation induced by high pulsatility flow, but drugs changing dynamics of F-actin enhanced NF-?B activation even under low pulsatility flow. Taxol was further circulated in the flow to examine its effect on cells. Results showed that circulating taxol (10nM) reduced PAEC polarity, NF-?B activation, gene expression of pro-inflammatory molecules (ICAM-1 and VCAM-1), and monocyte adhesion on the PAECs under high pulsatility flow. Therefore, taxol effectively reduced high pulsatility flow-induced PAEC overpolarization and pro-inflammatory responses via inhibiting cytoskeletal remodeling. This study suggests that stabilizing microtubule dynamics might bea potential therapeutic means of reducing endothelial inflammation caused by high pulsatility flow. PMID:23667401

Li, Min; Tan, Yan; Stenmark, Kurt R; Tan, Wei

2013-03-01

221

Enzyme and root activities in surface-flow constructed wetlands.  

PubMed

Sixteen small-scale wetlands planted with four plant species were constructed for domestic wastewater purification. The objective of this study was to determine the correlations between contaminant removal and soil enzyme activity, root activity, and growth in the constructed wetlands. The results indicated that correlations between contaminant removal efficiency and enzyme activity varied depending on the contaminants. The removal efficiency of NH4+ was significantly correlated with both urease and protease activity in all wetlands, and the removal of total phosphorus and soluble reactive phosphorus was significantly correlated with phosphatase activity in most wetlands, while the removal of total nitrogen, NO3(-) , and chemical oxygen demand (COD) was significantly correlated with enzyme activity only in a few instances. Correlations between soil enzyme activity and root activity varied among species. Activities of all enzymes were significantly correlated with root activity in Vetiveria zizanioides and Phragmites australis wetlands, but not in Hymenocallis littoralis wetlands. Significant correlations between enzyme activity and root biomass and between enzyme activity and root growth were found mainly in Cyperus flabelliformis wetlands. Root activity was significantly correlated with removal efficiencies of all contaminants except NO3(-) and COD in V. zizanioides wetlands. Enzyme activities and root activity showed single-peak seasonal patterns. Activities of phosphatase, urease, and cellulase were significantly higher in the top layer of the substrate than in the deeper layers, and there were generally no significant differences between the deeper layers (deeper than 15 cm). PMID:19497608

Kong, Ling; Wang, Yu-Bin; Zhao, Li-Na; Chen, Zhang-He

2009-06-03

222

Standing-Gradient Flows Driven by Active Solute Transport.  

National Technical Information Service (NTIS)

The paper shows that a relatively simple analytic treatment preserves the main features of the equations governing coupled solute and water flow in a long channel closed at one end. Until now, these equations have only been treated numerically. Among the ...

L. A. Segel

1970-01-01

223

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

224

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

225

Muscle activation during low-intensity muscle contractions with restricted blood flow  

Microsoft Academic Search

We examined muscle activation during low-intensity muscle contractions with a moderate restriction of blood flow and complete occlusion of blood flow. Unilateral elbow flexion muscle contractions (20% of 1-RM) were performed in Experiment 1 (30 contractions), Experiment 2 (3 sets × 10 contractions), and Experiment 3 (30 repetitive contractions followed by 3 sets × 15 contractions) with moderate restriction, complete occlusion of blood flow

Tomohiro Yasuda; William F Brechue; Taku Fujita; Jun Shirakawa; Yoshiaki Sato; Takashi Abe

2009-01-01

226

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

227

Evaluation of nutrient removal efficiency and microbial enzyme activity in a baffled subsurface-flow constructed wetland system.  

PubMed

In this study, the enzyme activities and their relationships to domestic wastewater purification are investigated in four different types of subsurface-flow constructed wetlands (CWs), namely the traditional horizontal subsurface-flow, horizontal baffled subsurface-flow, vertical baffled subsurface-flow, and composite baffled subsurface-flow CWs. Results showed that the urease activity in the composite baffled subsurface-flow CW was significantly higher than in the other three CWs, while the phosphatase activity in the vertical baffled subsurface-flow CW were higher than in the other three CWs. There were significant and very significant correlations between the activities of urease and the removal rates of TN and NH4(+)-N for the horizontal baffled flow, horizontal subsurface flow, and composite baffled subsurface flow CWs. This study suggests that the activity of urease in the root zones of those three CWs is an important indicator for N purification from wastewaters. PMID:23982062

Cui, Lihua; Ouyang, Ying; Gu, Wenjie; Yang, Weizhi; Xu, Qiaoling

2013-07-29

228

Solar Energy Education. Renewable energy activities for earth science  

SciTech Connect

A teaching manual is provided to aid teachers in introducing renewable energy topics to earth science students. The main emphasis is placed on solar energy. Activities for the student include a study of the greenhouse effect, solar gain for home heating, measuring solar radiation, and the construction of a model solar still to obtain fresh water. Instructions for the construction of apparatus to demonstrate a solar still, the greenhouse effect and measurement of the altitude and azimuth of the sun are included. (BCS)

Not Available

1980-01-01

229

Thermal radiance observations of an active lava flow during the June 1984 eruption of Mount Etna  

SciTech Connect

The thermal budget of an active lava flow observed on 20 June 1984 from the Southeast crater of Mount Etna, Sicily, Italy, was analyzed from data taken by the Landsat Thematic Mapper. The Thematic Mapper images constitute one of the few satellite data sets of sufficient spatial and spectral resolution to allow calibrated measurements on the distribution and intensity of thermal radiation from active lava flows. Using radiance data from two reflective infrared channels, we can estimate the temperature and areas of the hottest parts of the active flow, which correspond to hot (>500{degree}C) fractures or zones at the flow surface. Using this techniques, we estimate that only 10%-20% of the total radiated thermal power output is emitted by hot zones or fractures, which constitute less than 1% of the observed surface area. Generally, it seems that only where hot fractures or zones constitute greater than about 1% of the surface area of the flow will losses from such features significantly reduce internal flow temperatures. Using our radiance observations as boundary conditions for a multicomponent thermal model of flow interior temperature, we infer that, for the parts of this flow subject to analysis, the boundary layer and flow thickness effects dominate over radiant zones in controlling the depression of core temperature.

Pieri, D.C.; Glaze, L.S.; Abrams, M.J. (California Institute of Technology, Pasadena (USA))

1990-10-01

230

Using Springs to Study Groundwater Flow and Active Geologic Processes  

NASA Astrophysics Data System (ADS)

Spring water provides a unique opportunity to study a range of subsurface processes in regions with few boreholes or wells. However, because springs integrate the signal of geological and hydrological processes over large spatial areas and long periods of time, they are an indirect source of information. This review illustrates a variety of techniques and approaches that are used to interpret measurements of isotopic tracers, water chemistry, discharge, and temperature. As an example, a set of springs in the Oregon Cascades is considered. By using tracers, temperature, and discharge measurements, it is possible to determine the mean-residence time of water, infer the spatial pattern and extent of groundwater flow, estimate basin-scale hydraulic properties, calculate the regional heat flow, and quantify the rate of magmatic intrusion beneath the volcanic arc.

Manga, Michael

231

Seismic characterization of pyroclastic flow activity at Soufrière Hills Volcano, Montserrat, 8 January 2007  

Microsoft Academic Search

A partial dome collapse with concurrent pyroclastic flow (PF) activity occurred at Soufrière Hills Volcano (SHV), Montserrat on 8 January 2007. Pyroclastic density currents were observed to propagate from the Northwest and West sectors of the summit dome into the heads of Tyres Ghaut and Gages Valley, respectively. Between 10:00 and 10:15 UTC pyroclastic flows entered Tyres Ghaut and from

S. de Angelis; V. Bass; V. Hards; G. Ryan

2007-01-01

232

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

233

Superdiffusive wave front propagation in a chemical active flow  

NASA Astrophysics Data System (ADS)

We present experiments on the propagation of a wave front in a fluid forced by Faraday waves. The vertical periodical modulation of the acceleration induces flows in the system that modifies the Belousov-Zhabotinsky (BZ) chemical reaction dynamics. Phase waves spreading through standing waves with different symmetries results in superdiffusion. The anomalous diffusion is characterized in terms of a non-integer transport exponent which is compared with exponents resulting from tracer particles trajectories undergoing rapid, distant jumps called Lévy flights.

Fernández-García, G.; Pérez-Muñuzuri, V.

2008-12-01

234

U. S. energy production activity and innovation  

Microsoft Academic Search

Life-cycle studies provide a comprehensive insight into comparative innovation behavior and innovation constants. In this article a comparison of the life-cycle plots for the production and patent activity is made for US energy production categories. As has been shown previously for material production [TFSC, vol.78, 2011], the two activities may be correlated to such an extent that they may be

Michael C. Connelly; J. A. Sekhar

235

Systematic study of the energy of vanishing flow: Role of equations of state and cross sections  

SciTech Connect

We present a systematic study of the energy of vanishing flow by considering symmetric colliding nuclei (between {sup 12}C and {sup 238}U) at normalized impact parameters using variety of equations of state (with and without momentum dependent interactions) as well as different nucleon-nucleon cross sections. A perfect power law mass dependence is obtained in all the cases which passes through calculated points nicely. Further, the choice of impact parameter affects the energy of vanishing flow drastically, demanding a very accurate measurement of the impact parameter. However, the energy of vanishing flow is less sensitive towards the equation of state as well as its momentum dependence.

Sood, Aman D.; Puri, Rajeev K. [Department of Physics, Panjab University, Chandigarh 160 014 (India)

2006-06-15

236

Nonstationary flow in the model channel of a ramjet engine in pulse-periodic energy supply  

NASA Astrophysics Data System (ADS)

A study has been made of the influence of the pulse-periodic supply of energy that is equal to the energy released in the combustion of hydrogen in air on the structure of supersonic flow in a channel of variable cross section, modeling the duct of a ramjet engine. The flow has been modeled on the basis of two-dimensional nonstationary gas-dynamic equations. Different flow regimes have been obtained depending on the configuration of the zones of energy supply and the excess-air coefficients.

Zamuraev, V. P.; Kalinina, A. P.

2008-05-01

237

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

238

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

239

Active ultrasonic cross-correlation flowmeters for mixed-phase pipe flows. [Solid\\/liquid and solid\\/gas flows  

Microsoft Academic Search

This paper describes two ultrasonic flowmeters which employ the active cross-correlation technique and uses a simple clamp-on transducer arrangement. The flowmeter for solid\\/liquid flows was tested over a wide range of coal concentration in water and oil. The measured velocity based on the peak position of the cross-correlation function is consistently higher by about 15% than the average velocity measured

S. H. Sheen; A. C. Raptis

1984-01-01

240

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.

241

Activation Energies of Acceleration and Hypoxia Stress.  

National Technical Information Service (NTIS)

The activation energy of 13 kcal/M for loss of peripheral vision in man subjected to acceleration stress of +4 to +5 Gz resembles that of 12 kcal/M for survival of rats of +40 Gz, which suggests that the physiological mechanisms of acceleration protection...

F. W. Cope

1970-01-01

242

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

243

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…

Minnesota State Energy Agency, St. Paul.

244

P2X7 receptor as sensitive flow sensor for ERK activation in osteoblasts  

Microsoft Academic Search

The involvement of the P2 receptor in the activation of ERK induced by a short transient fluid flow stimulation in MC3T3-E1 osteoblasts was examined in the current study. The ERK activation induced by this transient fluid flow stimulation was followed by an increase in c-fos mRNA expression. Suramin, a non-selective P2 receptor antagonist, and two different P2X7 receptor (P2X7R) antagonists,

Hisashi Okumura; Dai Shiba; Toshikazu Kubo; Takahiko Yokoyama

2008-01-01

245

Cross-flow microfiltration of activated sludge using submerged membrane with air bubbling  

Microsoft Academic Search

For the purpose of developing a wastewater treatment membrane bioreactor system, cross-flow microfiltration of intermittently aerated activated sludge was carried out, as a part of the solid-liquid separation process in the bioreactor. The tubular alumina microfiltration membrane, having a pore size of 0.5 ?m, was submerged in the activated sludge. A cross-flow stream over the membrane surface was produced by

Yasutoshi Shimizu; Katsushi Uryu; Yu-Ichi Okuno; Atsuo Watanabe

1996-01-01

246

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

247

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

248

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

249

Energy flow and charged particle spectra in deep inelastic scattering at HERA  

Microsoft Academic Search

Global properties of the hadronic final state in deep inelastic scattering events at HERA are investigated. The data are corrected for detector effects and are compared directly with QCD phenomenology. Energy flows in both the laboratory frame and the hadronic centre of mass system and energy-energy correlations in the laboratory frame are presented. Comparing various QCD models, the colour dipole

I. Abt; T. Ahmed; V. Andreev; S. Aid; B. Andrieu; R.-D. Appuhn; M. Arpagaus; A. Babaev; H. Bärwolff; J. Bán; P. Baranov; E. Barrelet; W. Bartel; U. Bassler; H. P. Beck; H.-J. Behrend; A. Belousov; Ch. Berger; H. Bergstein; G. Bernardi; R. Bernet; G. Bertrand-Coremans; M. Besançon; P. Biddulph; E. Binder; J. C. Bizot; V. Blobel; K. Borras; P. C. Bosetti; V. Boudry; C. Bourdarios; A. Braemer; F. Brasse; U. Braun; W. Braunschweig; V. Brisson; D. Bruncko; L. Büngener; J. Bürger; F. W. Büsser; A. Buniatian; S. Burke; G. Buschhorn; A. J. Campbell; T. Carli; F. Charles; J. Chyla; D. Clarke; A. B. Clegg; M. Colombo; J. A. Coughlan; A. Courau; Ch. Coutures; G. Cozzika; L. Criegee; J. Cvach; S. Dagoret; J. B. Dainton; M. Danilov; A. W. E. Dann; W. D. Dau; M. David; E. Deffur; B. Delcourt; L. Del Buono; M. Devel; A. De Roeck; P. Di Nezza; P. Dingus; C. Dollfus; J. D. Dowell; H. B. Dreis; A. Drescher; J. Duboc; D. Düllmann; O. Dünger; H. Duhm; R. Ebbinghaus; M. Eberle; J. Ebert; T. R. Ebert; G. Eckerlin; V. Efremenko; S. Egli; H. Ehrlichmann; S. Eichenberger; R. Eichler; F. Eisele; E. Eisenhandler; N. N. Ellis; R. J. Ellison; E. Elsen; M. Erdmann; E. Evrard; L. Favart; A. Fedotov; D. Feeken; R. Felst; J. Feltesse; I. F. Fensome; J. Ferencei; F. Ferrarotto; K. Flamm; W. Flauger; M. Fleischer; M. Flieser; G. Flügge; A. Fomenko; B. Fominykh; M. Forbush; J. Formánek; J. M. Foster; G. Franke; E. Fretwurst; P. Fuhrmann; E. Gabathuler; K. Gamerdinger; J. Garvey; J. Gayler; M. Gebauer; A. Gellrich; M. Gennis; H. Genzel; R. Gerhards; L. Godfrey; U. Goerlach; L. Goerlich; N. Gogitidze; M. Goldberg; D. Goldner; A. M. Goodall; I. Gorelov; P. Goritchev; C. Grab; H. Grässler; T. Greenshaw; H. Greif; G. Grindhammer; A. Gruber; C. Gruber; J. Haack; D. Haidt; L. Hajduk; O. Hamon; M. Hampel; E. M. Hanlon; M. Hapke; J. Harjes; R. Haydar; W. J. Haynes; J. Heatherington; V. Hedberg; G. Heinzelmann; R. C. W. Henderson; H. Henschel; R. Herma; I. Herynek; W. Hildesheim; P. Hill; C. D. Hilton; J. Hladký; K. C. Hoeger; M. Höppner; Ph. Huet; H. Hufnagel; N. Huot; M. Ibbotson; H. Itterbeck; M.-A. Jabiol; A. Jacholkowska; C. Jacobsson; M. Jaffre; T. Jansen; L. Jönsson; K. Johannsen; D. P. Johnson; L. Johnson; H. Jung; P. I. P. Kalmus; D. Kant; S. Kazarian; R. Kaschowitz; P. Kasselmann; U. Kathage; H. H. Kaufmann; I. R. Kenyon; S. Kermiche; C. Keuker; C. Kiesling; M. Klein; C. Kleinwort; G. Knies; W. Ko; T. Köhler; H. Kolanoski; F. Kole; S. D. Kolya; V. Korbel; M. Korn; P. Kostka; S. K. Kotelnikov; M. W. Krasny; D. Krücker; U. Krüger; J. P. Kubenka; H. Küster; M. Kuhlen; T. Kurca; J. Kurzhöfer; B. Kuznik; D. Lacour; F. Lamarche; R. Lander; M. P. J. Landon; W. Lange; R. Langkau; P. Lanius; J. F. Laporte; A. Lebedev; A. Leuschner; C. Leverenz; S. Levonian; D. Lewin; Ch. Ley; A. Lindner; G. Lindström; F. Linsel; J. Lipinski; P. Loch; H. Lohmander; G. C. Lopez; D. Lüers; D. Lüke; N. Magnussen; E. Malinovski; S. Mani; P. Marage; J. Marks; R. Marshall; J. Martens; R. Martin; H.-U. Martyn; J. Martyniak; S. Masson; A. Mavroidis; S. J. Maxfield; S. J. McMahon; A. Mehta; K. Meier; D. Mercer; T. Merz; C. A. Meyer; H. Meyer; J. Meyer; S. Mikocki; E. Monnier; F. Moreau; J. Moreels; J. V. Morris; K. Müller; P. Murín; S. A. Murray; V. Nagovizin; B. Naroska; Th. Naumann; P. R. Newman; D. Newton; D. Neyret; H. K. Nguyen; F. Niebergall; C. Niebuhr; R. Nisius; G. Nowak; G. W. Noyes; M. Nyberg; H. Oberlack; U. Obrock; J. E. Olsson; S. Orenstein; F. Ould-Saada; C. Pascaud; G. D. Patel; E. Peppel; S. Peters; H. T. Phillips; J. P. Phillips; Ch. Pichler; W. Pilgram; D. Pitzl; S. Prell; R. Prosi; G. Rädel; F. Raupach; K. Rauschnabel; P. Reimer; S. Reinshagen; P. Ribarics; V. Riech; J. Riedlberger; S. Riess; M. Rietz; S. M. Robertson; P. Robmann; R. Roosen; K. Rosenbauer; A. Rostovtsev; C. Royon; M. Rudowicz; M. Ruffer; S. Rusakov; K. Rybicki; N. Sahlmann; E. Sanchez; D. P. C. Sankey; M. Savitsky; P. Schacht; P. Schleper; W. von Schlippe; C. Schmidt; D. Schmidt; W. Schmitz; A. Schöning; V. Schröder; E. Schuhmann; M. Schulz; B. Schwab; A. Schwind; W. Scobel; U. Seehausen; R. Sell; A. Semenov; V. Shekelyan; I. Sheviakov; H. Shooshtari; L. N. Shtarkov; G. Siegmon; U. Siewert; Y. Sirois; I. O. Skillicorn; P. Smirnov; J. R. Smith; Y. Soloviev; H. Spitzer; M. Steenbock; P. Steffen; R. Steinberg; B. Stella; K. Stephens; J. Stier; U. Stösslein; J. Strachota; U. Straumann; W. Struczinski; J. P. Sutton; R. E. Taylor; V. Tchernyshov; C. Thiebaux; G. Thompson; I. Tichomirov; P. Truöl; J. Turnau; J. Tutas; L. Urban; A. Usik; S. Valkar; A. Valkarova; C. Vallée; P. Van Esch; A. Vartapetian; Y. Vazdik; M. Vecko; P. Verrecchia; R. Vick; G. Villet; E. Vogel; K. Wacker; I. W. Walker; A. Walther; G. Weber; D. Wegener; A. Wegener; H. P. Wellisch; L. R. West; S. Willard; M. Winde; G.-G. Winter; Th. Wolff; L. A. Womersley; A. E. Wright

1994-01-01

250

Energy and Materials Flows in the Production of Liquid and Gaseous Oxygen.  

National Technical Information Service (NTIS)

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 ...

S. Shen A. M. Wolsky

1980-01-01

251

Energy/Material Flows Associated with Cyclic Petrochemicals.  

National Technical Information Service (NTIS)

A detailed product flow analysis, starting with the refinery reformate stream, was prepared to identify the major products of interest. The selection of the products and their derivatives for detailed analysis was based on 1978 consumption data which is r...

1979-01-01

252

Rheological control on the radiant density of active lava flows and domes  

NASA Astrophysics Data System (ADS)

During an effusive-extrusive eruption, the capability of an active lava body (flow or dome) to radiate thermal energy depends on how the lava discharge rate is accommodated by the expansion of the magma body and by the cooling of its surface. This feature can be described by a single empirical parameter, defined "radiant density" (crad; in J m- 3) that, for a given discharge rate, expresses the efficiency of the lava body to change its area and/or to insulate its inner core, thus modulating the heat radiated from the active surface. By comparing the Volcanic Radiative Energy (VRE; in J), detected by MODIS during 28 eruptions at 18 active volcanoes, with their erupted lava volumes (Vol; in m3), we show that the radiant density (crad = VRE/Vol) is inversely proportional to the silica content of the erupted lava. Basic lavas (45-52 wt.% SiO2) have the highest observed radiant density (1 to 4 × 108 J m- 3) while intermediate (52-63 wt.% SiO2) and acidic (> 63 wt.% SiO2) lavas show a gradually lower radiant densities (1.5 to 9 × 107 J m- 3 and 0.2 to 1 × 107 J m- 3 for intermediate and acidic composition, respectively). We regard this correlation as the result of the control that the rheology of lavas exerts on cooling and spreading processes of related bodies. In particular, we found that for any given compositional group the radiant density is essentially related to a "characteristic thickness" of active lavas, at the time of a satellite acquisition.We suggest that the radiant density of effusive/extrusive lava bodies can be predicted (± 50%) by means of an empirical relationship based on the SiO2 content of the erupted lava. This makes this parameter very useful in observing volcanic activity, especially in remote regions where access may not be possible. By measuring the energy radiated during an eruption and by assuming a lava composition (based on the tectonic setting or magmatic province), we suggest that the radiant density can be used to estimate lava discharge rates and erupted volumes for volcanoes characterised by effusive or extrusive activity.

Coppola, D.; Laiolo, M.; Piscopo, D.; Cigolini, C.

2013-01-01

253

On the convergence and singularities of theJ-Flow with applications to the Mabuchi energy  

Microsoft Academic Search

The J-flow of S. K. Donaldson and X. X. Chen is a parabolic flow on Kahler\\u000amanifolds with two Kahler metrics. It is the gradient flow of the J-functional\\u000awhich appears in Chen's formula for the Mabuchi energy. We find a positivity\\u000acondition in terms of the two metrics which is both necessary and sufficient\\u000afor the convergence of the

Jian Song; Benjamin Weinkove

2008-01-01

254

Energy Spectra of Flow Past a Circular Cylinder  

Microsoft Academic Search

Unsteady flow past a circular cylinder is computed for 100<=Re<=107. A stabilized finite element formulation is utilized to solve the incompressible flow equations in the primitive variables form. Close to the cylinder and in the wake region, the finite element mesh has very high resolution. The phenomenon of drag crisis (sudden drop in drag v\\/s Re at Re˜2×105) is captured

Satya Prakash Singh; Sanjay Mittal

2004-01-01

255

Active Control of Aeroelasticity and Internal Flows in Turbomachinery.  

National Technical Information Service (NTIS)

The research conducted was focused in two areas. The first is active control of rotating stall when inlet distortion is present. This research was carried out on the low speed 3-stage active control research compressor at MIT=GTL. The second area of resea...

A. H. Epstein J. D. Paduano E. M. Greitzer

1996-01-01

256

Flow-injection-type biosensor system for salivary amylase activity  

Microsoft Academic Search

The authors aim to establish a method that can quantitatively evaluate vital reactions to stress. We have been examining the correlation between stress and salivary amylase activity in order to verify its validity as a stress index. In order to quantify human stress, which changes over time, the relationship between stress and salivary amylase activity must be verified by fast

Masaki Yamaguchi; Masashi Kanemaru; Takahiro Kanemori; Yasufumi Mizuno

2003-01-01

257

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

2009-12-10

258

Experimental investigations of the swirling flow in the conical diffuser using flow-feedback control technique with additional energy source  

NASA Astrophysics Data System (ADS)

The previous experimental and numerical investigations of decelerated swirling flows in conical diffusers have demonstrated that water injection along to the axis mitigates the pressure fluctuations associated to the precessing vortex rope [1]. However, for swirling flows similar to Francis turbines operated at partial discharge, the water jet becomes effective when the jet discharge is larger than 10% from the turbine discharge, leading to large volumetric losses when the jet is supplied from upstream the runner. As a result, it was introduced a new approach for supplying the jet by using a fraction of the discharge collected downstream the conical diffuser [2]. This is called flow-feedback control technique (FFCT) and it was investigated experimentally in order to assess its capability [3]. The FFCT approach not requires additional energy to supply the jet. Consequently, the turbine efficiency is not diminished due to the volumetric losses injected even if around 10% of the main flow is used. However, the equivalent amplitude of the pressure pulsations associated to the vortex rope decreases with 30% if 10% jet discharge is applied [3]. Using 12% water jet discharge from upstream then the equivalent amplitude of the pressure pulsations is mitigated with 70% according to Bosioc et al. [4]. In our case, an extra 2% jet discharge is required in order to obtain similar results with FFCT. This extra discharge is provided using an additional energy source. Therefore, the paper presents experimental investigation performed with FFCT with additional energy source. The experimental results obtained with this technique are compared against FFCT and the swirling flow with vortex rope, respectively.

T?nas?, C.; Bosioc, A. I.; Susan-Resiga, R. F.; Muntean, S.

2012-11-01

259

Nonmodal energy growth and optimal perturbations in compressible plane Couette flow  

Microsoft Academic Search

Nonmodal transient growth studies and an estimation of optimal perturbations have been made for the compressible plane Couette flow with three-dimensional disturbances. The steady mean flow is characterized by a nonuniform shear rate and a varying temperature across the wall-normal direction for an appropriate perfect gas model. The maximum amplification of perturbation energy over time, Gmax, is found to increase

M. Malik; Meheboob Alam; J. Dey

2006-01-01

260

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

261

DENITRIFICATION ACTIVITY THROUGH SUBSURFACE FLOW IN SANDBAR WITH VEGETATION  

NASA Astrophysics Data System (ADS)

River landscape with sandbar is composed of several elements such as vegetation, bare area, side-pool and so on. In recent years, it has been reported that sandbar (vegetation in particular) has water purification function, but the quantification of purification is still unknown. The purpose of this study is to examine how the nitrogen is trapped and retained by vegetation of sandbar through numerical calculation of subsurface flow based on field observation. The numerical simulation was performed under the discharge and the topographical conditions of the Yahagi river. The main results of this study are that the vegetation area of the sandbar has higher potential of denitrification than bare area. Also, it was clearly showed that the distribution of vegetation affected nitrogen dynamics. Thus, it has become possible to propose the effective distribution of vegetation for the maximization of the water purification function by using the numerical simulation.

Obana, Makiko; Toda, Yuji; Tsujimoto, Tetsuro; Nojiri, Kohei

262

Energy flow and power phenomena in electrical circuits: illusions and reality  

Microsoft Academic Search

Contents  ?Common opinions respective to the nature of the reactive power, energy flow and oscillations, as well as the notion of the\\u000a apparent power in single- and in three-phase systems are discussed in this paper. It is shown that some interpretations of\\u000a powers and energy flow in linear, single-phase circuits are often generalized for more complex situations where these interpretations\\u000a are

L. S. Czarnecki

2000-01-01

263

Distribution of Bacterial Growth Activity in Flow-Chamber Biofilms  

PubMed Central

In microbial communities such as those found in biofilms, individual organisms most often display heterogeneous 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 and different variant gfp genes. It is shown that the P1 promoter is regulated in the same way in E. coli and Pseudomonas putida, making it useful for monitoring of growth activity in organisms outside the group of enteric bacteria. Construction of fusions to genes encoding unstable Gfp proteins opened up the possibility of the monitoring of rates of rRNA synthesis and, in this way, allowing on-line determination of the distribution of growth activity in a complex community. With the use of these reporter tools, it is demonstrated that individual cells of a toluene-degrading P. putida strain growing in a benzyl alcohol-supplemented biofilm have different levels of growth activity which develop as the biofilm gets older. Cells that eventually grow very slowly or not at all may be stimulated to restart growth if provided with a more easily metabolizable carbon source. Thus, the dynamics of biofilm growth activity has been tracked to the level of individual cells, cell clusters, and microcolonies.

Sternberg, Claus; Christensen, Bjarke B.; Johansen, Tove; Toftgaard Nielsen, Alex; Andersen, Jens Bo; Givskov, Michael; Molin, S?ren

1999-01-01

264

System size, energy, pseudorapidity, and centrality dependence of elliptic flow.  

PubMed

This Letter 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. 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. PMID:17677957

Alver, B; Back, B B; Baker, M D; Ballintijn, M; Barton, D S; Betts, R R; Bickley, A A; Bindel, R; Busza, W; Carroll, A; Chai, Z; Chetluru, V; Decowski, M P; García, E; Gburek, T; George, N; Gulbrandsen, K; Halliwell, C; Hamblen, J; Harnarine, I; Hauer, M; Henderson, C; Hofman, D J; Hollis, R S; Ho?y?ski, R; Holzman, B; Iordanova, A; Johnson, E; Kane, J L; Khan, N; Kulinich, P; Kuo, C M; Li, W; Lin, W T; Loizides, C; Manly, S; Mignerey, A C; Nouicer, R; Olszewski, A; Pak, R; Reed, C; Richardson, E; Roland, C; Roland, G; Sagerer, J; Seals, H; Sedykh, I; Smith, C E; Stankiewicz, M A; Steinberg, P; Stephans, G S F; Sukhanov, A; Szostak, A; Tonjes, M B; Trzupek, A; Vale, C; van Nieuwenhuizen, G J; Vaurynovich, S S; Verdier, R; Veres, G I; Walters, P; Wenger, E; Willhelm, D; Wolfs, F L H; Wosiek, B; Wo?niak, K; Wyngaardt, S; Wys?ouch, B

2007-06-15

265

Turbulent kinetic energy spectrum in very anisothermal flows  

NASA Astrophysics Data System (ADS)

In this Letter, we find that the Kolmogorov scaling law is no longer valid when the flow is submitted to strong dilatational effects caused by high temperature gradients. As a result, in addition to the nonlinear time scale, there is a much shorter "temperature gradients" time scale. We propose a model that estimates the time scale of the triple decorrelation incorporating the influences of the temperature gradient. The model agrees with the results from the thermal large-eddy simulations of different Reynolds numbers and temperature gradients. This Letter provides a better understanding of the very anisothermal turbulent flow.

Serra, Sylvain; Toutant, Adrien; Bataille, Françoise; Zhou, Ye

2012-10-01

266

Joint moment control of mechanical energy flow during normal gait  

Microsoft Academic Search

The study purpose was to estimate the ability of joint moments to transfer mechanical energy through the leg and trunk during gait. A segmental power analysis of five healthy adult subjects revealed that internal joint extensor moments removed energy from the leg and added energy to the trunk, while flexor moments and gravity produced the opposite effects. The only exception

Karen Lohmann Siegel; Thomas M Kepple; Steven J Stanhope

2004-01-01

267

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

NASA Astrophysics Data System (ADS)

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.

Thomas, Lawrence E.

2012-09-01

268

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

269

Development of piezoelectric microcantilever flow sensor with wind-driven energy harvesting capability  

NASA Astrophysics Data System (ADS)

We have developed a piezoelectric (PZT) microcantilever as an air flow sensor and a wind-driven energy harvester for a self-sustained flow-sensing microsystem. A flow sensing sensitivity of 0.9 mV/(m/s) is obtained. The output voltage and optimized power regarding to the load resistance of 100 k? are measured as 18.1 mV and 3.3 nW at flow velocity of 15.6 m/s, respectively. The corresponding power density is as large as 0.36 mW/cm3. The experimental results have elucidated the smart function of using PZT microcantilevers as flow-sensors and wind-driven energy harvesters simultaneously.

Liu, Huicong; Zhang, Songsong; Kathiresan, Ramprakash; Kobayashi, Takeshi; Lee, Chengkuo

2012-05-01

270

Elliptical flow and isospin effects in heavy-ion collisions at intermediate energies  

SciTech Connect

The elliptical flow of fragments is studied for different systems at incident energies between 50 and 1000 MeV/nucleon using the isospin-dependent quantum molecular dynamics (IQMD) model. Our findings reveal that elliptical flow shows a transition from positive (in-plane) to negative (out-of-plane) values in the midrapidity region at a certain incident energy known as the transition energy. This transition energy is found to depend on the model ingredients, size of the fragments, and composite mass of the reacting system as well as on the impact parameter of the reaction. A reasonable agreement is observed for the excitation function of elliptical flow between the data and our calculations. Interestingly, the transition energy is found to exhibit a power-law mass dependence.

Kumar, Sanjeev; Kumar, Suneel; Puri, Rajeev K. [School of Physics and Material Science, Thapar University, Patiala-147004, Punjab (India); Department of Physics, Panjab University, Chandigarh-160014 (India)

2010-01-15

271

Multifragmentation at the energy of vanishing flow in central heavy-ion collisions  

SciTech Connect

We studied the fragmentation of colliding nuclei at the energy of vanishing flow and evaluated its mass dependence throughout the periodic table. This study was performed within the framework of the quantum molecular dynamics model, which has been reported to reproduce the experimental data at low incident energies quite nicely. We simulated as many as 11 reactions for which the balance energy had been measured experimentally. Our observations at the energy of vanishing flow clearly suggest the existence of a power law system mass dependence for various fragment multiplicities. The power factor {tau}({proportional_to}A{sup {tau}}) is close to (-1/3), as has also been reported for the mass dependence of the energy of vanishing flow. Experiments are needed to verify these predictions.

Dhawan, Jatinder K.; Puri, Rajeev K. [Physics Department, Panjab University, Chandigarh 160 014 (India)

2006-11-15

272

Ciliary motility activity measurement using a dense optical flow algorithm.  

PubMed

Persistent respiratory syncytial virus (RSV) infections have been associated with the exacerbation of chronic inflammatory diseases, including chronic obstructive pulmonary disease (COPD). This virus infects the respiratory epithelium, leading to chronic inflammation, and induces the release of mucins and the loss of cilia activity, two factors that determine mucus clearance and the increase in sputum volume. PMID:24110720

Parrilla, Eduardo; Armengot, Miguel; Mata, Manuel; Cortijo, Julio; Riera, Jaime; Hueso, Jose L; Moratal, David

2013-07-01

273

Three-Dimensional MHD Models of Waves and Flows in Coronal Active Region Loops  

NASA Astrophysics Data System (ADS)

Recent observations show that slow magnetosonic waves are present in active region loops, and are often associated with subsonic up-flows of coronal material. In order to study the relation between up-flows and waves we develop a 3D MHD model of an idealized bi-polar active region with flows in coronal loops. The model is initiated with a dipole magnetic field and gravitationally stratified isothermal atmosphere. To model the effects of flares, coronal material is injected in small-scale regions at the base of the model active region. The up-flows have sub-sonic speeds of ˜100 km/s and are steady or periodic, producing higher density loops by filling magnetic flux-tubes with injected material. We find that the up-flows produce fast and slow magnetosonic waves that propagate in the coronal loops. We perform a parametric study of up-flow magnitude and periodicity, and the relation with the resulting waves. As expected, we find that the up-flow speed decreases with loop height due to the diverge of the flux tubes, while the slow magnetosonic speed is independent of height. When the amplitude of the driving pulses is increased above the sound speed, we find that slow shocks are produced in the loops. Using the results of the 3D MHD model we show that observed slow magnetosonic waves in active region loops can be driven by impulsive flare-produced up-flows at the transition region/corona interface of active regions.

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

2011-12-01

274

Two-dimensional distribution of microbial activity and flow patterns within naturally fractured chalk  

NASA Astrophysics Data System (ADS)

The two-dimensional distribution of flow patterns and their dynamic change due to microbial activity were investigated in naturally fractured chalk cores. Long-term biodegradation experiments were conducted in two cores (˜20 cm diameter, 31 and 44 cm long), intersected by a natural fracture. 2,4,6-tribromophenol (TBP) was used as a model contaminant and as the sole carbon source for aerobic microbial activity. The transmissivity of the fractures was continuously reduced due to biomass accumulation in the fracture concurrent with TBP biodegradation. From multi-tracer experiments conducted prior to and following the microbial activity, it was found that biomass accumulation causes redistribution of the preferential flow channels. Zones of slow flow near the fracture inlet were clogged, thus further diverting the flow through zones of fast flow, which were also partially clogged. Quantitative evaluation of biodegradation and bacterial counts supported the results of the multi-tracer tests, indicating that most of the bacterial activity occurs close to the inlet. The changing flow patterns, which control the nutrient supply, resulted in variations in the concentrations of the chemical constituents (TBP, bromide and oxygen), used as indicators of biodegradation.

Arnon, Shai; Ronen, Zeev; Adar, Eilon; Yakirevich, Alexander; Nativ, Ronit

2005-10-01

275

'Explosive' wave interactions of zero energy in inviscid fluid flows  

NASA Astrophysics Data System (ADS)

Second harmonic wave interactions in stratified shear flows are analyzed for the case where both wavenumbers are on the linear stability boundary. For the 'explosive' self-similar solution to the amplitude equations, two integrals are obtained. It is found that the explosions considered are the fastest of all known explosions for inhomogeneous nondissipative media.

Moiseev, S. S.; Pungin, V. G.; Suiazov, N. V.; Etkin, V. S.

1984-09-01

276

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

277

Land Use, Energy Flow, and Decision Making in Human Society. Volume 4: Models of Global Pollution by Energy Systems.  

National Technical Information Service (NTIS)

The volume describes models of global pollution by energy systems in a study to develop simulation models of land use and energy flow in human society, with special attention to the State of California. It contains conclusions from simulation studies base...

A. Epes R. Boyd W. B. Crews T. Petersen J. Young

1973-01-01

278

Automated Methodologies for the Design of Flow Diagrams for Development and Maintenance Activities  

NASA Astrophysics Data System (ADS)

The Software Requirements Specification (SRS) of the organization is a text document prepared by strategic management incorporating the requirements of the organization. These requirements of ongoing business/ project development process involve the software tools, the hardware devices, the manual procedures, the application programs and the communication commands. These components are appropriately ordered for achieving the mission of the concerned process both in the project development and the ongoing business processes, in different flow diagrams viz. activity chart, workflow diagram, activity diagram, component diagram and deployment diagram. This paper proposes two generic, automatic methodologies for the design of various flow diagrams of (i) project development activities, (ii) ongoing business process. The methodologies also resolve the ensuing deadlocks in the flow diagrams and determine the critical paths for the activity chart. Though both methodologies are independent, each complements other in authenticating its correctness and completeness.

Shivanand M., Handigund; Shweta, Bhat

279

Energy Adventure Center. Activity Book. Revised [and Expanded] Edition.  

ERIC Educational Resources Information Center

|A variety of energy activities are provided, including instructions for and questions related to energy films. The activities are organized into five sections. Section 1 (work) includes an activity focusing on movement and change. Section 2 (forms of energy) includes activities related to mechanical (movement), radiant (light), chemical…

Wichita Unified School District 259, KS.

280

Hydrodynamic flow caused by active transport along cytoskeletal elements  

NASA Astrophysics Data System (ADS)

We develop a simple lattice model to describe the hydrodynamic influence of active mass transport along bio-filaments on freely diffusing mass in the cell. To quantify the overall mass transport we include Brownian motion, excluded volume interactions, active transport along the filaments, and hydrodynamic interactions. The model shows that the hydrodynamic forces induced by molecular motors attached to the filaments give rise to a non-negligible flux close to the filament. This additional flux appears to have two effects. Depending on the degree of filament occupation it can exert a sufficiently large influence on unbound motors and cargo to modify their transport and also regulate the flux of motors bound to the filament. We expect such a mechanism is important in situations found in plant cells, where directional transport spans the entire cell. In particular, it can explain the cytoplasmic streaming observed in plant cells.

Houtman, D.; Pagonabarraga, I.; Lowe, C. P.; Esseling-Ozdoba, A.; Emons, A. M. C.; Eiser, E.

2007-04-01

281

The kinetic energy budget over the West Pacific during dominant trade wind and active monsoon regimes  

Microsoft Academic Search

From upper-air network data and NMC tropical wind analyses over the West Pacific . during July 1972 and July 1975, the kinetic energy balance in large-scale disturbances and in the general flow of the tropical circulation was calculated. During July 1972, when an active monsoon and its attendant intertropical convergence zone (ITCZ) dominated much of the tropical West Pacific and

Yihui Ding; Elmar R. Reiter

1983-01-01

282

Determination of ECoG information flow activity based on Granger causality and Hilbert transformation.  

PubMed

Analysis of directional information flow patterns among different regions of the brain is important for investigating the relation between ECoG (electrocorticographic) and mental activity. The objective is to study and evaluate the information flow activity at different frequencies in the primary motor cortex. We employed Granger causality for capturing the future state of the propagation path and direction between recording electrode sites on the cerebral cortex. A grid covered the right motor cortex completely due to its size (approx. 8cm×8cm) but grid area extends to the surrounding cortex areas. During the experiment, a subject was asked to imagine performing two activities: movement of the left small finger and/or movement of the tongue. The time series of the electrical brain activity was recorded during these trials using an 8×8 (0.016-300Hz band with) ECoG platinum electrode grid, which was placed on the contralateral (right) motor cortex. For detection of information flow activity and communication frequencies among the electrodes, we have proposed a method based on following steps: (i) calculation of analytical time series such as amplitude and phase difference acquired from Hilbert transformation, (ii) selection of frequency having highest interdependence for the electrode pairs for the concerned time series over a sliding window in which we assumed time series were stationary, (iii) calculation of Granger causality values for each pair with selected frequency. The information flow (causal influence) activity and communication frequencies between the electrodes in grid were determined and shown successfully. It is supposed that information flow activity and communication frequencies between the electrodes in the grid are approximately the same for the same pattern. The successful employment of Granger causality and Hilbert transformation for the detection of the propagation path and direction of each component of ECoG among different sub-cortex areas were capable of determining the information flow (causal influence) activity and communication frequencies between the populations of neurons successfully. PMID:24070543

Demirer, R Murat; Ozerdem, Mehmet Siraç; Bayrak, Coskun; Mendi, Engin

2013-09-01

283

Disturbed blood flow acutely induces activation and apoptosis of the human vascular endothelium.  

PubMed

There is strong and consistent evidence from in vitro studies that disturbed blood flow produces a proatherogenic vascular endothelial phenotype. However, data from human studies are lacking. To address this, a 220 mm Hg occlusion cuff was placed on the distal forearm of 10 young, healthy men to induce a localized region of disturbed blood flow in the proximal vasculature for 20 minutes. We hypothesized that disturbed blood flow would induce endothelial activation and apoptosis as indicated by increases in local concentrations of CD62E(+) and CD31(+)/CD42b(-) endothelial microparticles, respectively. Distal cuff occlusion induced reductions in mean blood flow, mean shear, and antegrade shear, and increases in retrograde flow, retrograde shear, and oscillatory shear stress, confirming that our protocol produced a disturbed blood flow stimulus in the experimental arm. Relative to baseline (0 minutes), CD62E(+) endothelial microparticles increased by ?3-fold at 10 minutes and ?4-fold at 20 minutes in the experimental arm (P<0.05). CD31(+)/CD42b(-) endothelial microparticles were elevated by ?9-fold at the 20 minutes time point (P<0.05). There were no changes in the concentrations of either endothelial microparticle population throughout the experiment in the contralateral arm, exposed to normal resting blood flow (no cuffs). These findings indicate that disturbed blood flow acutely induces endothelial activation and apoptosis in humans, as reflected by release of microparticles from activated (CD62E(+)) and apoptotic (CD31(+)/CD42b(-)) endothelial cells. These data provide the first in vivo experimental evidence of disturbed blood flow-induced endothelial injury in humans. PMID:23319545

Jenkins, Nathan T; Padilla, Jaume; Boyle, Leryn J; Credeur, Daniel P; Laughlin, M Harold; Fadel, Paul J

2013-01-14

284

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

285

Energy harvesting using semi-active control  

NASA Astrophysics Data System (ADS)

This paper presents the application of semi-active control for optimising the power harvested by an electro-mechanical energy harvester. A time-periodic damper, defined by a Fourier series, is introduced for energy harvesting in order to increase the performance of the device. An analytical solution for the transmissibility and the average absorbed power is derived based on the method of harmonic balance. The coefficients of the semi-active model are optimised to maximise the harvested power. The harvested power from the optimum periodic time-varying damper at a particular frequency is compared and is shown to be greater than that from an optimum passive damper and a semi-active on-off damper not only at that particular frequency but also at other frequencies. In addition, the performance of the optimised periodic time-varying damper is also compared with an arbitrary semi-active time-periodic damper, which has the same transmissibility at resonance. An optimisation is carried out to maximise the power in a frequency range and the optimum damper is derived as a function of the excitation frequency. The numerical results are validated with the analytical approach.

Di Monaco, Francesco; Ghandchi Tehrani, Maryam; Elliott, Stephen J.; Bonisoli, Elvio; Tornincasa, Stefano

2013-11-01

286

High energy activation data library (HEAD-2009)  

NASA Astrophysics Data System (ADS)

A proton activation data library for 682 nuclides from 1H 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.

Korovin, Yu. A.; Natalenko, A. A.; Stankovskiy, A. Yu.; Mashnik, S. G.; Konobeyev, A. Yu.

2010-12-01

287

Global Energy Flows and their Food System Components1  

Microsoft Academic Search

The rate at which the Earth's surface receives high-utility energy from the Sun is 11,000 times as great as the rate at which humans use commercial energy. Despite this, 88 percent of the commercial energy used comes from non-renewable, fossil-fuel sources. Fossil fuel use each year adds 3 percent more carbon-dioxide to the atmosphere than natural sinks can remove. The

William J. Chancellor

2001-01-01

288

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 deviation of the mean. Our observations show that these waves are continually radiated outward from the flow toward the auroral oval, low latitude boundary layer or lobes and that over several Earth-radii the integrated energy loss from the flow channel can be comparable to the total energy content of the flow itself. We find that this plasma sheet energy loss process is particularly effective within |XGSE| ? 15 RE.

Chaston, C. C.; Bonnell, J. W.; Clausen, L.; Angelopoulos, V.

2012-09-01

289

The effect of respiratory activity on brain blood flow during exposure to +Gz acceleration.  

PubMed

The effect of respiratory activity on cardiovascular system during the exposure to +Gz acceleration was studied. For simultaneous, beat to beat evaluation of central and global cerebral blood flow, the system based on modified impedance cardiography method was used. The mechanism of modulation of the central and peripheral (cerebral) venous pressures and blood flow by intrathoracic pressure changes, has been shown. The data obtained from these studies suggest that reconsideration of the respiration technique during Anti-GSM seems indispensable. PMID:11540262

Walichnowski, W; Kowalski, W; Bulski, W

1996-09-01

290

Generic Transport Aft-body Drag Reduction using Active Flow Control  

Microsoft Academic Search

Active flow-separation control is an effective and efficient mean for drag reduction and unsteady load alleviation resulting\\u000a from locally or massively separated flow. Such a situation occurs in configurations where the aerodynamic performance is of\\u000a secondary importance to functionality. The performance of heavy transport helicopters and aeroplanes, having a large, and\\u000a almost flat, aft loading ramp suffer from the poor

Eli Ben-Hamou; Eran Arad; Avi Seifert

2007-01-01

291

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

292

Gravitational field-flow fractionation for the characterisation of active dry wine yeast  

Microsoft Academic Search

Gravitational field-flow fractionation (GrFFF) is applied to the fractionation of active dry wine yeast. An experimental approach to the analysis of the effects that field variation by changing mobile phase composition and flow-rate have on the fractionation process of standard particles (polystyrene) was first developed to further obtain effective fractionation of wine yeast by GrFFF. Scanning electron microscopy and Coulter

R Sanz; L Puignou; P Reschiglian; M. T Galceran

2001-01-01

293

Conductive heat flow at the TAG active hydrothermal mound: Results from 1993-1995 submersible surveys  

Microsoft Academic Search

We report 70 measurements of conductive heat flow at the 50-m-high, 200-m-diameter TAG active hydrothermal mound, made during submersible surveys with Alvin in 1993 and 1995 and Shinkai 6500 in 1994. The stations were all measured with 5-thermistor, 0.6- or 1-m-long Alvin heat flow probes, which are capable of determining both gradient and thermal conductivity, and were transponder-navigated to an

K. Becker; R. von Herzen; J. Kirklin; R. Evans; D. Kadko; M. Kinoshita; O. Matsubayashi; R. Mills; A. Schultz; P. Rona

1996-01-01

294

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

2010-03-01

295

Tumulus development on lava flows: insights from observations of active tumuli and analysis of formation models  

NASA Astrophysics Data System (ADS)

Here, we use observations of active flows along with detailed morphometric field measurements of more than 70 tumuli on flows at Mount Etna (Italy), Kilauea, and Hualalai (US) volcanoes to constrain a previously published model that estimates the pressure needed to form tumuli. In an attempt to discover the nature and magnitude of pressure variations within active lava flow interiors, we then consider how tumuli differ from idealized circular plates. We incorporate observations of active tumuli and find that they may grow asymmetrically yet produce a symmetrical tumulus and can form where the flow path significantly changes direction. Bending models of clamped edges provide the most reasonable head estimates for the tumuli in our study. Tumulus formation requires the proper combination of cooling and effusion rate. If cooling is too extensive and effusion rate too low, the crust will provide too much resistance to bending. If cooling is too limited and effusion rates too high, crusts will not develop or have insufficient strength to resist fracture and subsequent breakouts. We do not find it surprising that tumuli are rarely found over well-established lava tubes that typically have rigid, walls/overlying crusts that exceed 2 m in thickness and provide too much resistance to bending. Silicic flows lack tumuli because the viscosity gradients within the flow are insufficient to concentrate stress in a localized area.

Anderson, Steven W.; Smrekar, Suzanne E.; Stofan, Ellen R.

2012-05-01

296

Seventeenth century organic agriculture in China: II. Energy flows through an agroecosystem in Jiaxing region  

Microsoft Academic Search

The energy flows in a seventeenth century agroecosystem in Jiaxing region of eastern China were analyzed on the basis of historical data. The agroecosystem included cropping, mulberry-silkworm, livestock, and fishing systems. In terms of energy, the agroecosystem was sustainable. Human labor provided all the power with inputs of about 3700 hr per hectare of farmland. Most or 70% of the

Wen Dazhong; David Pimentel

1986-01-01

297

Energy and materials flows in the fabrication of iron and steel semifinished products  

Microsoft Academic Search

The flow of energy and materials in the fabrication of iron and steel semifinished products from molten metal is discussed. The focus is on techniques to reduce the amount of energy required to produce the typical products of integrated steel plants and iron and steel foundries. In integrated steel plants, if only 50% of the steel being cast were continuously

J. B. Jr. Darby; R. M. Arons

1979-01-01

298

Leaf litter processing and energy flow through macroinvertebrates in a woodland pond (Switzerland)  

Microsoft Academic Search

Energy generated by leaf litter processing and its flow through the associated macroinvertebrate community was quantified in a pond near Geneva (Switzerland). Annual density, biomass, and production on oak (Quercus robur) leaf litter were assessed for all macroinvertebrate taxa with emphasis on predators. Empirical energetic relations provided an energy budget for the macroinvertebrate community. On 1 m2 of pond bottom,

B. Oertli

1993-01-01

299

Stoichiometry in Producer-Grazer Systems: Linking Energy Flow with Element Cycling  

Microsoft Academic Search

All organisms are composed of multiple chemical elements such as carbon, nitrogen and phosphorus. While energy flow and element cycling are two fundamental and unifying principles in ecosystem theory, population models usually ignore the latter. Such models implicitly assume chemical homogeneity of all trophic levels by concentrating on a single constituent, generally an equivalent of energy. In this paper, we

Irakli Loladze; Yang Kuang; James J. Elser

2000-01-01

300

Optimization and control of hydrogen and energy flows in a Green Hydrogen Refuelling Stations  

Microsoft Academic Search

In this paper, an optimization model of Green Hydrogen Refuelling Station (GHRS) is presented. The GHRS is powered completely by a wind farm to satisfy predefined hydrogen fuel and electrical energy demands. The model based on a mathematical programming is developed to control both energy and hydrogen flows exchanged among the system components. The optimization model has been applied on

Hanane Dagdougui; Ahmed Ouammi; Roberto Sacile

2011-01-01

301

An automated design flow for vibration-based energy harvester systems  

Microsoft Academic Search

This paper proposes, for the first time, an automated energy harvester design flow which is based on a single HDL software platform that can be used to model, simulate, configure and optimise energy harvester systems. A demonstrator pro- totype incorporating an electromagnetic mechanical-vibration- based micro-generator and a limited number of library models has been developed and a design case study

Leran Wang; Tom J. Kazmierski; Bashir M. Al-hashimi; Stephen P. Beeby; Dibin Zhu

2009-01-01

302

Energy and Materials Flows in the Production of Primary Aluminum.  

National Technical Information Service (NTIS)

The primary aluminum industry is one of the top five industrial energy users in the United States consuming about one quad annually. In 1980, for each ton of aluminum produced, an average smelting operation used about 157 million Btu of direct energy and ...

S. Y. Shen

1981-01-01

303

Energy flow for integrated apple production in Greece  

Microsoft Academic Search

Integrated production requires constant improvement of methods employed to achieve high fruit quality and yield with minimal inputs. This work was undertaken to evaluate the energy inputs for apple production, to identify the highest energy consuming operations and propose ways to improve them. Integrated production methods were employed during 1999 and 2000 at 26 apple (Malus domestica Borkh.) orchards in

Argiro V. Strapatsa; George D. Nanos; Constantinos A. Tsatsarelis

2006-01-01

304

Energy and materials flows in the iron and steel industry  

SciTech Connect

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 10/sup 15/ 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 consumption is estimated to be about 3.1 x 10/sup 15/ Btu. Of the set of conservation technologies identified, most are judged to be ready for commercialization if and when the industry's capital formation and profitability problems are solved and the gradual predicted increase in energy prices reduces the payback periods to acceptable levels.

Sparrow, F.T.

1983-06-01

305

Higher frequency network activity flow predicts lower frequency node activity in intrinsic low-frequency BOLD fluctuations.  

PubMed

The brain remains electrically and metabolically active during resting conditions. The low-frequency oscillations (LFO) of the blood oxygen level-dependent (BOLD) signal of functional magnetic resonance imaging (fMRI) coherent across distributed brain regions are known to exhibit features of this activity. However, these intrinsic oscillations may undergo dynamic changes in time scales of seconds to minutes during resting conditions. Here, using wavelet-transform based time-frequency analysis techniques, we investigated the dynamic nature of default-mode networks from intrinsic BOLD signals recorded from participants maintaining visual fixation during resting conditions. We focused on the default-mode network consisting of the posterior cingulate cortex (PCC), the medial prefrontal cortex (mPFC), left middle temporal cortex (LMTC) and left angular gyrus (LAG). The analysis of the spectral power and causal flow patterns revealed that the intrinsic LFO undergo significant dynamic changes over time. Dividing the frequency interval 0 to 0.25 Hz of LFO into four intervals slow-5 (0.01-0.027 Hz), slow-4 (0.027-0.073 Hz), slow-3 (0.073-0.198 Hz) and slow-2 (0.198-0.25 Hz), we further observed significant positive linear relationships of slow-4 in-out flow of network activity with slow-5 node activity, and slow-3 in-out flow of network activity with slow-4 node activity. The network activity associated with respiratory related frequency (slow-2) was found to have no relationship with the node activity in any of the frequency intervals. We found that the net causal flow towards a node in slow-3 band was correlated with the number of fibers, obtained from diffusion tensor imaging (DTI) data, from the other nodes connecting to that node. These findings imply that so-called resting state is not 'entirely' at rest, the higher frequency network activity flow can predict the lower frequency node activity, and the network activity flow can reflect underlying structural connectivity. PMID:23691225

Bajaj, Sahil; Adhikari, Bhim Mani; Dhamala, Mukesh

2013-05-15

306

Higher Frequency Network Activity Flow Predicts Lower Frequency Node Activity in Intrinsic Low-Frequency BOLD Fluctuations  

PubMed Central

The brain remains electrically and metabolically active during resting conditions. The low-frequency oscillations (LFO) of the blood oxygen level-dependent (BOLD) signal of functional magnetic resonance imaging (fMRI) coherent across distributed brain regions are known to exhibit features of this activity. However, these intrinsic oscillations may undergo dynamic changes in time scales of seconds to minutes during resting conditions. Here, using wavelet-transform based time-frequency analysis techniques, we investigated the dynamic nature of default-mode networks from intrinsic BOLD signals recorded from participants maintaining visual fixation during resting conditions. We focused on the default-mode network consisting of the posterior cingulate cortex (PCC), the medial prefrontal cortex (mPFC), left middle temporal cortex (LMTC) and left angular gyrus (LAG). The analysis of the spectral power and causal flow patterns revealed that the intrinsic LFO undergo significant dynamic changes over time. Dividing the frequency interval 0 to 0.25 Hz of LFO into four intervals slow-5 (0.01–0.027 Hz), slow-4 (0.027–0.073 Hz), slow-3 (0.073–0.198 Hz) and slow-2 (0.198–0.25 Hz), we further observed significant positive linear relationships of slow-4 in-out flow of network activity with slow-5 node activity, and slow-3 in-out flow of network activity with slow-4 node activity. The network activity associated with respiratory related frequency (slow-2) was found to have no relationship with the node activity in any of the frequency intervals. We found that the net causal flow towards a node in slow-3 band was correlated with the number of fibers, obtained from diffusion tensor imaging (DTI) data, from the other nodes connecting to that node. These findings imply that so-called resting state is not ‘entirely’ at rest, the higher frequency network activity flow can predict the lower frequency node activity, and the network activity flow can reflect underlying structural connectivity.

Bajaj, Sahil; Adhikari, Bhim Mani; Dhamala, Mukesh

2013-01-01

307

The California Energy Commission's geothermal activities  

SciTech Connect

Thank you for the invitation to participate in this distinguished gathering. I would like to briefly relate the interests of the California Energy Commission in geothermal energy. Geothermal energy is a basic component of many of our primary activities, and is expressly cited in our statutory authority, the Warren-Alquist Act (1974). Our mandates affect the geothermal industry both directly and indirectly. The Commission is responsible for 5-, 12-, and 20-year forecasts of California electricity supply and demand. These forecasts are reported in our biennial Electricity Report. These forecasts are used in various official regulatory proceedings. The primary use is in the Commission's power plant siting authority. The forecasts establish the base used to determine the need for new capacity and energy in the current planning period. The forecasts are also used in other Commission activities as well as in proceedings at the Public Utilities Commission. The 1990 Electricity Report represents a dramatic change in the way this agency balances the relative importance of price competition, environmental quality, demand management as a system resource, and the implications of continued reliance on natural gas. Generally, the Commission is grappling with the elusive and complex problems of quantifying the appropriate value to assign to external (i. e., non-market) environmental attributes of competing technologies. While we have not decisively established such values, we do believe that they do exist and that we are moving in the right direction. The adopted policies have positive long term implications for geothermal and the other renewable technologies. The Commission has been in existence since 1975 and during that time has seen the development of geothermal energy in several areas of the state. As a regulatory agency, we have authority over the construction of thermal electric plants over 50 megawatts (MW). To date the Commission has certified the construction of more than 1200 MW in the Geysers. This area is now experiencing a dramatic loss in productivity. The Commission is engaged in a cooperative effort with the parties operating in the Geysers to address the problem of resource productivity. We held a hearing to examine the causes of the decline of the geothermal steam resources and its affect on electric energy supply. An outcome of the hearing was the establishment of a Technical Advisory Committee with the responsibility of providing the Commission projections of capacity and energy under the current rates of steam decline. The Committee was also charged with examining options on efficient resource management, including research and development, testing, and analyses regarding reservoir and power plant operations.

Crowley, Barbara

1991-01-01

308

Collision energy dependence of viscous hydrodynamic flow in relativistic heavy-ion collisions  

NASA Astrophysics Data System (ADS)

Using a (2+1)-dimensional viscous hydrodynamical model, we study the dependence of flow observables on the collision energy ranging from s=7.7A GeV at the Relativistic Heavy Ion Collider (RHIC) to s=2760A GeV at the Large Hadron Collider (LHC). With a realistic equation of state, Glauber model initial conditions, and a small specific shear viscosity ?/s=0.08, the differential charged hadron elliptic flow v2ch(pT,s) is found to exhibit a very broad maximum as a function of s around top RHIC energy, rendering it almost independent of collision energy for 39?s?2760A GeV. Compared to ideal fluid dynamical simulations, this “saturation” of elliptic flow is shifted to higher collision energies by shear viscous effects. For color-glass-motivated Monte Carlo-Kharzeev-Levin-Nardi initial conditions, which require a larger shear viscosity ?/s=0.2 to reproduce the measured elliptic flow, a similar saturation is not observed up to LHC energies, except for very low pT. We emphasize that this saturation of the elliptic flow is not associated with the QCD phase transition, but arises from the interplay between radial and elliptic flow, which shifts with s depending on the fluid's viscosity and leads to a subtle cancellation between increasing contributions from light particles and decreasing contributions from heavy particles to v2 in the s range, where v2ch(pT,s) at fixed pT is maximal. By generalizing the definition of spatial eccentricity ?x to isothermal hypersurfaces, we calculate ?x on the kinetic freeze-out surface at different collision energies. Up to top RHIC energy, s=200A GeV, the fireball is still out-of-plane deformed at freeze-out, while at LHC energy the final spatial eccentricity is predicted to approach zero.

Shen, Chun; Heinz, Ulrich

2012-05-01

309

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

310

ENERGY LOSS AT THREE-WAY CIRCULAR MANHOLE UNDER SURCHARGE FLOW  

NASA Astrophysics Data System (ADS)

The energy loss at manholes in a storm sewer network is often compared with the friction loss in pipes under a surcharge flow. It is important to estimate the energy loss at manholes exactly in the design of a storm sewer network and in a flood-analysis. Some researchers have already investigated the energy loss at three-way manholes. However, the relationship between the energy loss and the water depth in manholes has not been enough studied yet. In this study, the effect of the water depth and the ratio of the flow rates in the lateral and in the downstream pipes on the energy loss at a three-way circular manhole was investigated. This study also proposed a modified formula for energy loss coefficients described in Urban Drainage Design Manual, USA (2001) for the three-way manhole.

Arao, Shinji; Moriyama, Katsumi; Asada, Jyunsaku; Hirose, Nozomu; Kusuda, Tetsuya

311

Time- and Volume-Averaged Conservation Equations for Multiphase Flow Using Mass-Weighted Velocity and Internal Energy.  

National Technical Information Service (NTIS)

Conservation equations of mass, momentum, and energy for multiphase flow, formulated on the basis of local volume averaging followed by time-averaging for turbulent flows, are presented. They are differential equations of transport with area integrals ass...

B. T. Chao S. L. Soo W. T. Sha

1988-01-01

312

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

313

Energy of vanishing flow: mass-isospin dependence  

Microsoft Academic Search

We study the effect of isospin degree of freedom on balance energy throughout\\u000athe mass range between 50 and 350 for two sets of isotopic systems with N\\/Z =\\u000a1.16 and 1.33 as well as isobaric systems with N\\/A = 1.0 and 1.4. Our findings\\u000aindicate that different values of balance energy for two isobaric systems may\\u000abe mainly due

Sakshi Gautam; Aman D. Sood; Rajeev K Puri

2011-01-01

314

Energy of vanishing flow: mass-isospin dependence  

Microsoft Academic Search

We study the effect of isospin degree of freedom on balance energy throughout the mass range between 50 and 350 for two sets of isotopic systems with N\\/Z = 1.16 and 1.33 as well as isobaric systems with N\\/A = 1.0 and 1.4. Our findings indicate that different values of balance energy for two isobaric systems may be mainly due

Sakshi Gautam; Aman D. Sood; Rajeev K Puri

2011-01-01

315

Performance of a piezoelectric energy harvester driven by air flow  

NASA Astrophysics Data System (ADS)

A turbulent wind source for possible energy harvesting is considered. To increase the amplitude of vibration, we apply a magnetopiezoelastic oscillator having a double well Duffing potential. The output voltage response of the system for different level of wind excitations is analyzed. The energy harvesting appeared to be the most efficient for the conditions close to the stochastic resonance region where the potential barrier was overcame.

Kitio Kwuimy, C. A.; Litak, G.; Borowiec, M.; Nataraj, C.

2012-01-01

316

CD63 cell expression detected by flow-cytometric determination of basophil activation in allergic patients.  

PubMed

Flow cytometry analysis of in vitro activated basophils (BATs) based on the detection of CD63 up-regulation on basophil membrane provides the physician and the clinical laboratory with a novel diagnostic approach, proposed as a promising alternative method for in vitro diagnosis of IgE and non-mediated reactions. We performed an optimized flow cytometric procedure to assess CD63 expression on activated basophils on twenty allergic patients, and compared the results with specific IgE determination (RAST) and skin testing (Prick test). PMID:23298505

Tammaro, A; Narcisi, A; Amodeo, R; Portaro, L; Tabacco, F; Cardelli, P; Persechino, S

317

Role of structural effects on the collective transverse flow and the energy of vanishing flow in nuclear collisions  

NASA Astrophysics Data System (ADS)

We address the question of why so far most of the simulation approaches to find the energy of vanishing flow (EVF) in light systems have failed to reproduce the experimental data. By investigating systematically the dependence of the EVF on the initial setup of the nuclei in these approaches we find out that for light systems a small variation of this setup can create large differences in the EVF whereas for large systems the dependence is weak. These studies have been done with the isospin-dependent quantum molecular dynamics model.

Bansal, Rajni; Gautam, Sakshi; Puri, Rajeev K.; Aichelin, J.

2013-06-01

318

Residential energy conservation outreach activities: A new federal approach  

NASA Astrophysics Data System (ADS)

An evaluation of the Department of Energy's residential energy conservation outreach activities is presented. The contribution that outreach can make in achieving energy conservation is examined. The effectiveness of alternative techniques and DOE's current program and management are also examined.

1981-02-01

319

78 FR 64414 - Assistance to Foreign Atomic Energy Activities  

Federal Register 2010, 2011, 2012, 2013

...Assistance to Foreign Atomic Energy Activities since 1986. The...subject to the Secretary of Energy's specific authorization...authorization by the Secretary of Energy. After careful consideration...The extension will facilitate conducting the second public meeting...

2013-10-29

320

The effects of activation procedures on regional cerebral blood flow in humans  

SciTech Connect

Regional cerebral blood flow (r-CBF) can be measured using 133XE and collimated detectors. The radionuclide can be administered either by inhalation or intracarotid injection. Comparison of blood flow determinations at rest and during performance of an activity identifies those brain regions that become active during the performance of the activity. Relatively specific patterns of r-CBF are observed during hand movements, sensory stimulation, eye movements, speech, listening, and reading. Regional CBF changes during reasoning and memorization are less specific and less well characterized. It is clear that brain lesions affect r-CBF responses to various activities, but this effect has not been well correlated with functional deficits or recovery of function. Regional CBF measurement gives information about brain activity and the functional response to experimental manipulation. This approach may well add to our understanding of normal, as well as pathologic, brain functioning.

Rozenfeld, D.; Wolfson, L.I.

1981-07-01

321

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

322

Anti-parallel EUV Flows Observed along Active Region Filament Threads with Hi-C  

NASA Astrophysics Data System (ADS)

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–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; Cirtain, Jonathan; Winebarger, Amy R.; Golub, Leon; Kobayashi, Ken; Platt, Simon; Mitchell, Nick; Korreck, Kelly; DePontieu, Bart; DeForest, Craig; Weber, Mark; Title, Alan; Kuzin, Sergey

2013-09-01

323

Apparatus for harvesting energy from flow-induced oscillations and method for the same  

US Patent & Trademark Office Database

A device and method for harvesting electrical power from kinetic energy of a flow. The electricity generator includes a vibration assembly and magnetic field source. The external gas or liquid flow causes a vibration of the assembly with an integrated conductive element, producing electricity in proximity of a magnetic field. The vibrating assembly has a set of resonant frequencies that correspond to a set of the frequencies of the flow vortices within a predetermined range of the external flow velocities. An arbitrary number of adjustable generators can be connected into a single circuit, either in-series or in-parallel, to increase an overall power output. It is capable to operate under wide range of flow characteristics and can serve as a virtually maintenance-free source of electrical power.

2012-09-04

324

Voltage Dependence of Activation Energy for Multilayer Ceramic Capacitors  

Microsoft Academic Search

Current-voltage and activation energy measurements can be used to probe grain boundary potential barriers. A common type of activation energy for Current conduction in a polycrystalline material is that due to the grain boundary potential barrier. Activation energy can be related directly to grain boundary barrier height. The height of this barrier depends on occupation of grain boundary states. Its

LARRY C. BURTON

1985-01-01

325

Analysis of energy transfers of a sheared flow generated by wall injection  

Microsoft Academic Search

We propose in this work to characterize the unsteady behavior of a flow generated by wall injection and encountering an obstacle.\\u000a This sutdy concerns the prediction of the stability of segmented solid propellant rocket motors. The simulation of such a\\u000a system is studied in cold flow, which makes it possible to analyze the basic phenomena and the energy transfer mechanisms

D. Couton; F. Plourde; S. Doan-Kim

1999-01-01

326

An Experimental Comparison of Min-cut\\/Max-flow Algorithms for Energy Minimization in Vision  

Microsoft Academic Search

After (15, 31, 19, 8, 25, 5) minimum cut\\/maximum flow algorithms on graphs emerged as an increasingly useful tool for exact or approximate energy minimization in low-level vision. The combinatorial optimization literature provides many min-cut\\/max-flow algorithms with different polynomial time complexity. Their practical efficiency, however, has to date been studied mainly outside the scope of computer vision. The goal of

Yuri Boykov; Vladimir Kolmogorov

2001-01-01

327

An Experimental Comparison of Min-Cut\\/Max-Flow Algorithms for Energy Minimization in Vision  

Microsoft Academic Search

Abstract After [15, 31, 19, 8, 25, 5] minimum cut\\/maximum flow algorithms on graphs emerged as an increasingly useful tool for exact or approximate,energy minimization,in low-level vision. The combinatorial,optimization,literature provides many,min-cut\\/max-flow algorithms with different polynomial time complexity. Their practical efficiency, however, has to date been studied mainly,outside the scope of computer,vision. The goal of this paper is to provide an

Yuri Boykov; Vladimir Kolmogorov

2004-01-01

328

The phenomenon of super energy flows in the anisotropic left-handed material  

NASA Astrophysics Data System (ADS)

The super energy flows generated and transmitted have been investigated in a parallel-plate waveguide, which is filled with air and the anisotropic left-handed materials. Theoretical analysis and numerical simulations show that the propagation modes of the anisotropic super waveguide are consistent with those of the isotropic waveguides [1-3]. They also show that the loss of electromagnetic parameters size of waveguide will influence the amplitude of time-average power flows.

Xu, Bai Bing; Yu, Guan Xia; Xia, Li Juan; Wang, Zhi Yuan

2013-01-01

329

The phenomenon of super energy flows in the anisotropic left-handed material  

NASA Astrophysics Data System (ADS)

The super energy flows generated and transmitted have been investigated in a parallel-plate waveguide, which is filled with air and the anisotropic left-handed materials. Theoretical analysis and numerical simulations show that the propagation modes of the anisotropic super waveguide are consistent with those of the isotropic waveguides [1-3]. They also show that the loss of electromagnetic parameters size of waveguide will influence the amplitude of time-average power flows.

Xu, Bai Bing; Yu, Guan Xia; Xia, Li Juan; Wang, Zhi Yuan

2012-10-01

330

Discrete kinetic energy conservation for variable-density flows on staggered grids  

Microsoft Academic Search

It is now conventional wisdom that ``kinetic-energy (KE)-conserving'' numerical methods are to be preferred for use in large-eddy simulation due to accuracy and stability considerations. For constant-density flows, KE-conserving schemes generally require central differencing and it is common practice to simply apply the same central differencing schemes to variable-density flows without the same rigorous stability guarantees. The theory for semi-discrete

Randall McDermott

2007-01-01

331

Measurement of anisotropic energy transport in flowing polymers by using a holographic technique  

Microsoft Academic Search

Almost no experimental data exist to test theories for the nonisothermal flow of complex fluids. To provide quantitative tests for newly proposed theories, we have developed a holographic grating technique to study energy transport in an amorphous polymer melt subject to flow. Polyisobutylene with weight-averaged molecular mass of 85 kDa is sheared at a rate of 10 s-1, and all

Jay D. Schieber; David C. Venerus; Kendall Bush; Venkat Balasubramanian; Stoyan Smoukov

2004-01-01

332

Active ultrasonic cross-correlation flowmeters for mixed-phase pipe flows  

NASA Astrophysics Data System (ADS)

Two ultrasonic flowmeters which employ the active cross-correlation technique and use a simple clamp-on transducer arrangement are discussed. The flowmeter for solid/liquid flows was tested over a wide range of coal concentration in water and oil. The measured velocity based on the peak position of the cross-correlation function is consistently higher by about 15% than the average velocity measured by flow diversion. The origin of the difference results mainly from the flow velocity profiles and the transit-time probability distribution. The flowmeter that can measure particle velocity in a solid/gas flow requires acoustic decoupling arrangement between two sensing stations. The measured velocity is mainly associated with the particles near the wall. Performance of both flowmeters is presented.

Sheen, S. H.; Raptis, A. C.

333

Influence of Dissipated Forming Energy on Flow Curves of Austenitic Stainless Steel  

NASA Astrophysics Data System (ADS)

Finite element (FE) simulations are widely used to design sheet metal forming processes. Flow curves and forming limit curves of the semi-finished goods are required for these computations. Mostly flow curves are obtained by conversions of stress-strain caracteristics from uniaxial tensile tests. In these calculations, uniform strain and stress within the gauge length is postulated until reaching elongation without necking. This precondition is true only if specimens remain homogenous during the test procedure. Effects from dissipated mechanical energy and heat flow on the results of uniaxial tensile tests were examined with specimen made of austenitic stainless steels with practical experiments and FE simulations.

Steinheimer, Rainer; Engel, Bernd

2011-08-01

334

Modeling of Free-Surface Liquid Flows for Heat Removal in FusionEnergy Systems  

SciTech Connect

One of the most promising methods for cooling & extracting plasma energy from a nuclear fusion reactor is via the flow of a liquid metal (Lithium) or molten salt (Flibe) over the inner concave surface that is facing the hot plasma. Such a flow is replete with physical issues concerning the stability, shape and controllability of the free surface, further complicated by the presence of strong magnetic fields. Numerical simulation of such flows is yet in a relatively primitive stage and stands to gain tremendously from advances in computational technologies over the past decade.

Shankar Vijaya, Munipalli Ramakanth, Hadid Ali

2001-05-16

335

Interrelation of Tissue Temperature Versus Flow Velocity in Two Different Kinds of Temperature Controlled Catheter Radiofrequency Energy Applications  

Microsoft Academic Search

The influence of blood flow cooling down the energy delivering electrode during temperature controlled radiofrequency energy application is an important factor for ablation success. In this experimental in-vitro study, using tempered saline as blood equivalent, we observed a highly significant increase in tissue temperature, lesion depth and required energy amount with increasing flow velocity. Second, we found significant deeper lesions

Stephan Grumbrecht; Jörg Neuzner; Heinz F. Pitschner

1998-01-01

336

Energy flow in non-equilibrium conformal field theory  

NASA Astrophysics Data System (ADS)

We study the energy current and its fluctuations in quantum gapless 1d systems far from equilibrium modeled by conformal field theory, where two separated halves are prepared at distinct temperatures and glued together at a point contact. We prove that these systems converge towards steady states, and give a general description of such non-equilibrium steady states in terms of quantum field theory data. We compute the large deviation function, also called the full counting statistics, of energy transfer through the contact. These are universal and satisfy fluctuation relations. We provide a simple representation of these quantum fluctuations in terms of classical Poisson processes whose intensities are proportional to Boltzmann weights.

Bernard, Denis; Doyon, Benjamin

2012-09-01

337

Nuclear in-medium effects and collective flows in heavy-ion collisions at intermediate energies  

NASA Astrophysics Data System (ADS)

A recent updated version of Lanzhou quantum molecular dynamics, in which the momentum dependence of the symmetry potential and the effective mass splitting of protons and neutrons in the nuclear medium are included in the model, is reviewed,. The in-medium nucleon-nucleon (NN) elastic cross sections are evaluated with the scaling approach according to the effective mass and their influence on collective flows in heavy-ion collisions are discussed. The inelastic cross sections, in particular for the process of the channel N?? NN, are parametrized in accordance with the available experimental data. It is found that the in-medium cross sections play a significant role in isospin emission and result in a flatter distribution for transverse flows and elliptic flows of free nucleons compared with the in-vacuum ones. The rapidity distribution of the difference between neutron and proton transverse flows is sensitive to the stiffness of the nuclear symmetry energy as a promising observable, which cannot be influenced by the in-medium effect and collision centrality. Furthermore, the elliptic flow of free energetic nucleons in the case of the mass splitting of mn*>mp* is also related to the symmetry energy. However, the pion flows weakly depend on the symmetry energy and the mass splitting.

Feng, Zhao-Qing

2012-01-01

338

A possible theory for the interaction between convective activities and vortical flows  

NASA Astrophysics Data System (ADS)

Theoretical studies usually attribute convections to the developments of instabilities such as the static or symmetric instabilities of the basic flows. However, the following three facts make the validities of these basic theories unconvincing. First, it seems that in most cases the basic flow with balance property cannot exist as the exact solution, so one cannot formulate appropriate problems of stability. Second, neither linear nor nonlinear theories of dynamical instability are able to describe a two-way interaction between convection and its background, because the basic state which must be an exact solution of the nonlinear equations of motion is prescribed in these issues. And third, the dynamical instability needs some extra initial disturbance to trigger it, which is usually another point of uncertainty. The present study suggests that convective activities can be recognized in the perspective of the interaction of convection with vortical flow. It is demonstrated that convective activities can be regarded as the superposition of free modes of convection and the response to the forcing induced by the imbalance of the unstably stratified vortical flow. An imbalanced vortical flow provides not only an initial condition from which unstable free modes of convection can develop but also a forcing on the convection. So, convection is more appropriately to be regarded as a spontaneous phenomenon rather than a disturbance-triggered phenomenon which is indicated by any theory of dynamical instability. Meanwhile, convection, particularly the forced part, has also a reaction on the basic flow by preventing the imbalance of the vortical flow from further increase and maintaining an approximately balanced flow.

Zhao, N.; Shen, X. Y.; Ding, Y. H.; Takahashi, M.

2011-10-01

339

Evolution of an active lava flow field using a multitemporal LIDAR acquisition  

NASA Astrophysics Data System (ADS)

Application of light detection and ranging (LIDAR) technology in volcanology has developed rapidly over the past few years, being extremely useful for the generation of high-spatial-resolution digital elevation models and for mapping eruption products. However, LIDAR can also be used to yield detailed information about the dynamics of lava movement, emplacement processes occuring across an active lava flow field, and the volumes involved. Here we present the results of a multitemporal airborne LIDAR survey flown to acquire data for an active flow field separated by time intervals ranging from 15 min to 25 h. Overflights were carried out over 2 d during the 2006 eruption of Mt. Etna, Italy, coincident with lava emission from three ephemeral vent zones to feed lava flow in six channels. In total 53 LIDAR images were collected, allowing us to track the volumetric evolution of the entire flow field with temporal resolutions as low as ˜15 min and at a spatial resolution of <1 m. This, together with accurate correction for systematic errors, finely tuned DEM-to-DEM coregistration and an accurate residual error assessment, permitted the quantification of the volumetric changes occuring across the flow field. We record a characteristic flow emplacement mode, whereby flow front advance and channel construction is fed by a series of volume pulses from the master vent. Volume pulses have a characteristic morphology represented by a wave that moves down the channel modifying existing channel-levee constructs across the proximal-medial zone and building new ones in the distal zone. Our high-resolution multitemporal LIDAR-derived DEMs allow calculation of the time-averaged discharge rates associated with such a pulsed flow emplacement regime, with errors under 1% for daily averaged values.

Favalli, M.; Fornaciai, A.; Mazzarini, F.; Harris, A.; Neri, M.; Behncke, B.; Pareschi, M. T.; Tarquini, S.; Boschi, E.

2010-11-01

340

Material and Energy Flows in the Materials Production, Assembly, and End-of-Life Stages of the Automotive Lithium-Ion Battery Life Cycle.  

National Technical Information Service (NTIS)

This document contains material and energy flows for lithium-ion batteries with an active cathode material of lithium manganese oxide (LiMn(sub 2)O(sub 4)). These data are incorporated into Argonne National Laboratory's Greenhouse gases, Regulated Emissio...

J. Sullivan J. B. Dunn L. Gaines M. Barnes M. Wang

2012-01-01

341

Adaptive Flow Control for Robust Performance and Energy  

Microsoft Academic Search

As chip multiprocessors scale the number of on chip cores, the superior scalability of multihop networks compared to buses and crossbars makes multihop networks the choice interconnection strategy. However, a significant part of the networks’ energy is consumed in the buffers used to handle link contention via back pressured routing. Recent work proposes to apply well-known backpressure less routing techniques,

Syed Ali Raza Jafri; Yu-Ju Hong; Mithuna Thottethodi; T. N. Vijaykumar

2010-01-01

342

Residential energy monitoring and computerized surveillance via utility power flows  

Microsoft Academic Search

The author notes that all novel technologies have the potential to affect society in a complex manner, with both beneficial and detrimental consequences. He considers an illustrative case study: a nonintrusive appliance load monitoring technique that can provide vital information to help avoid future energy crises, but can also be used for surveillance purposes. He notes that there appears to

George W. Hart; S. D. Warren; L. D. Brandeis

1989-01-01

343

Wind energy: an application of Bernoulli's theorem generalized to isentropic flow of ideal gases  

NASA Astrophysics Data System (ADS)

By considering the extension of Bernoulli's theorem to the case of the isentropic flow of ideal gases we conceive a small-scale wind-energy system able to work in the presence of low wind velocities in any direction. The flow of air inside a hyperbolically shaped pipe is studied using elementary physics concepts. The results obtained show that wind velocity in the system increases for decreasing cross-sectional areas, allowing a lower cut-in wind speed and an increase in the annual energy production of the device.

De Luca, R.; Desideri, P.

2013-01-01

344

Evolution of an active lava flow field using a multitemporal LIDAR acquisition  

Microsoft Academic Search

Application of light detection and ranging (LIDAR) technology in volcanology has developed rapidly over the past few years, being extremely useful for the generation of high-spatial-resolution digital elevation models and for mapping eruption products. However, LIDAR can also be used to yield detailed information about the dynamics of lava movement, emplacement processes occuring across an active lava flow field, and

M. Favalli; A. Fornaciai; F. Mazzarini; A. Harris; M. Neri; B. Behncke; M. T. Pareschi; S. Tarquini; E. Boschi

2010-01-01

345

Understanding patrons' participation in activities at entertainment malls : A study in “flow  

Microsoft Academic Search

Purpose – This paper aims to apply concepts from “flow” paradigm to examine factors contributing to participation in entertainment and shopping activities at, and future patronage intent toward, entertainment shopping malls. Design\\/methodology\\/approach – Data were collected from 342 consumers via mall intercepts conducted at two major entertainment shopping malls located in major metropolitan areas in the US states of Arizona

Sherry L. Lotz; Mary Ann Eastlick; Anubha Mishra; Soyeon Shim

2010-01-01

346

Thermal radiance observations of an active lava flow during the June 1984 eruption of Mount Etna  

Microsoft Academic Search

The thermal budget of an active lava flow observed on 20 June 1984 from the Southeast crater of Mount Etna, Sicily, Italy, was analyzed from data taken by the Landsat Thematic Mapper. The Thematic Mapper images constitute one of the few satellite data sets of sufficient spatial and spectral resolution to allow calibrated measurements on the distribution and intensity of

David C. Pieri; Lori S. Glaze; Michael J. Abrams

1990-01-01

347

Active control of flow-induced vibrations of a flexible cylinder using direct velocity feedback  

Microsoft Academic Search

The use of a direct velocity feedback controller to attenuate actively vortex-induced vibrations of a flexible circular cylinder is described. The controller relies on its operation on an electromagnetic actuator, placed at a critical location inside the cylinder, to generate the control action necessary to resist the flow-induced excitations. The actuator is powered by a signal proportional and opposite to

A. Baz; J. Ro

1991-01-01

348

Tracing Attention and the Activation Flow in Spoken Word Planning Using Eye Movements  

Microsoft Academic Search

The flow of activation from concepts to phonological forms within the word production system was examined in 3 experiments. In Experiment 1, participants named pictures while ignoring superimposed distractor pictures that were semantically related, phonologically related, or unrelated. Eye movements and naming latencies were recorded. The distractor pictures affected the latencies of gaze shifting and vocal naming. The magnitude of

Ardi Roelofs

2008-01-01

349

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…

Roelofs, Ardi; Dijkstra, Ton; Gerakaki, Svetlana

2013-01-01

350

Blood flow and oxygen delivery to human brain during functional activity: Theoretical modeling and experimental data  

Microsoft Academic Search

Coupling of cerebral blood flow (CBF) and cerebral metabolic rate for oxygen (CMRO2) in physiologically activated brain states remains the subject of debates. Recently it was suggested that CBF is tightly coupled to oxidative metabolism in a nonlinear fashion. As part of this hypothesis, mathematical models of oxygen delivery to the brain have been described in which disproportionately large increases

Mark A. Mintun; Brian N. Lundstrom; Abraham Z. Snyder; Andrei G. Vlassenko; Gordon L. Shulman; Marcus E. Raichle

2001-01-01

351

Active Control of a Circular Cylinder Flow at Transitional Reynolds Numbers  

Microsoft Academic Search

Active and passive control of flow around a circular cylinder, at transitional Reynolds numbers was investigated experimentally\\u000a by measuring cylinder surface pressures and wake velocity profiles. Two- and three-dimensional passive boundary layer tripping\\u000a was considered and periodic active control using piezo-fluidic actuators was introduced from a two-dimensional slot that was\\u000a nearly tangential to the cylinder surface. The slot location was

A. Naim; D. Greenblatt; A. Seifert; I. Wygnanski

2007-01-01

352

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

353

The signature of dark energy on the local Hubble flow  

Microsoft Academic Search

Using N-body simulations of flat, dark energy-dominated cosmologies, we show that galaxies around simulated binary systems resembling the Local Group (LG) have low peculiar velocities, in good agreement with observational data. We have compared results for LG-like systems selected from large, high-resolution simulations of three cosmologies: a LambdaCDM model, a LambdaWDM model with a 2-keV warm dark matter candidate, and

Andrea V. Macciò; Fabio Governato; Cathy Horellou

2005-01-01

354

Classical simulation of quantum energy flow in biomolecules.  

PubMed

Based on a comparison of classical and quantum-mechanical perturbation theory, the validity of classical nonequilibrium molecular dynamics simulations to describe vibrational energy redistribution in biomolecules is studied. Adopting a small model peptide in aqueous solution as an example, the theory correctly predicts quantum correction factors that need to be applied to the results of classical simulations in order to match the correct quantum results. PMID:19392249

Stock, Gerhard

2009-03-19

355

Chemical energy release and dynamics of transitional, reactive shear flows  

Microsoft Academic Search

Using a numerical model, the effects of diffusive transport, chemical energy release, and the free-stream-reactant molar fraction on the development of shear-layer in a compressible subsonic chemically reacting mixing layer are investigated together with the dependence of these effects on initial conditions. The system studied consisted of a (single-frequency) forced mixing layer formed by dilute nonpremixed subsonic streams of hydrogen

F. F. Grinstein; K. Kailasanath

1992-01-01

356

A biomass energy flow chart for Sierra Leone  

Microsoft Academic Search

Terrestrial above-ground biomass production and utilisation in Sierra Leone was analysed for the years 1984\\/5 to 1990\\/1. The total production of biomass energy was estimated at an annual average of 131 PJ (39% from agriculture, 51% from forestry and 10% from livestock). Of the 117 PJ produced from agricultural and forestry operations, 37 PJ was harvested as firewood and burnt

K Amoo-Gottfried; D. O Hall

1999-01-01

357

Valuing uncertain cash flows from investments that enhance energy efficiency.  

PubMed

There is a broad consensus that investments to enhance energy efficiency quickly pay for themselves in lower energy bills and spared emission allowances. However, investments that at first glance seem worthwhile usually are not undertaken. One of the plausible, non-excluding explanations is the numerous uncertainties that these investments face. This paper deals with the optimal time to invest in an energy efficiency enhancement at a facility already in place that consumes huge amounts of a fossil fuel (coal) and operates under carbon constraints. We follow the Real Options approach. Our model comprises three sources of uncertainty following different stochastic processes which allows for application in a broad range of settings. We assess the investment option by means of a three-dimensional binomial lattice. We compute the trigger investment cost, i.e., the threshold level below which immediate investment would be optimal. We analyze the major drivers of this decision thus aiming at the most promising policies in this regard. PMID:23295678

Abadie, Luis M; Chamorro, José M; González-Eguino, Mikel

2013-01-05

358

Energy Balance in the Solar Transition Region. IV. Hydrogen and Helium Mass Flows with Diffusion  

NASA Astrophysics Data System (ADS)

In this paper we extend our previous modeling of energy balance in the chromosphere-corona transition region to cases with particle and mass flows. The cases considered here are quasi-steady and satisfy the momentum and energy balance equations in the transition region. We assume one-dimensional geometry and include the flow velocity terms in all equations, but we neglect the partial derivatives with respect to time. We present a complete and physically consistent formulation and method for solving the non-LTE and energy balance equations in these situations, including both particle diffusion and flows of H and He. Our calculations include partial frequency redistribution in the Ly? and Ly? lines. Our results show quantitatively how mass flows affect the ionization and radiative losses of H and He, thereby affecting the structure and extent of the transition region. Furthermore, our computations show that the H and He line profiles are greatly affected by flows. We find that line shifts are much less important than the changes in line intensity and central reversal as a result of the influence of flows on the excitation and ionization. In this paper we use fixed conditions at the base of the transition region and in the underlying chromosphere. Our intent is to show the physical effects of flows on the transition region, not to match any particular observations. However, our computed Ly? profiles can account for the range of observed high spectral and spatial resolution from the quiet Sun. We suggest that dedicated modeling of specific sequences of observations based on physically consistent methods like those presented here will substantially improve our understanding of the energy balance in the chromosphere and corona.

Fontenla, J. M.; Avrett, E. H.; Loeser, R.

2002-06-01

359

Beyond surface heat flow: An example from a tectonically active sedimentary basin  

NASA Astrophysics Data System (ADS)

Thermal anomalies that have important geodynamic implications may not always be recognizable in present-day surface heat-flow patterns. The masking occurs because surface heat flow responds to mantle heat, crustal radioactivity, magmatism, crustal deformation, burial and/or exhumation, and fluid movement, any of which may offset the thermal effects of the others. Sedimentary basins are particularly suited to partitioning heat flow into its various components. We use Taranaki basin, New Zealand, as an example. It has a relatively undeformed (since the Miocene) western region that is used as a control against which the tectonically active eastern region can be compared. Although surface heat flow is roughly constant across Taranaki basin, basal heat flow modeled at lower crustal upper mantle depths varies by a factor of two or more. A combination of low heat-producing crust and the heat sink effects of crustal thickening in the eastern region can account for the basal heat-flow anomalies. The tectonic thermal anomaly would have gone unnoticed without the aid of detailed basin analysis and thermal modeling.

Armstrong, Phillip A.; Chapman, David S.

1998-02-01

360

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

361

Active Flow Control of Large Separation: A New Look at Scaling Parameters.  

NASA Astrophysics Data System (ADS)

Recently, there have been significant advances in the application of various methods of Active Flow Control (AFC) for controlling separated flows. The most popular method of AFC used recently is Zero-Mass Flux (ZMF). Traditionally, the scaling parameters used to evaluate effectiveness of ZMF control have been the momentum coefficient C? and the non-dimensional frequency F^+. While this scaling has worked well for certain types of flows, i.e. flows with small separated regions, exhibiting separated shear layers susceptible to instabilities and development of coherent structures, it is not the proper choice for flows with large separated regions, especially with three dimensionality and high Reynolds numbers. This became evident in a couple of recent tests where ZMF was used with large separated regions, including the first ever full-scale flight demonstration of AFC; the DARPA/Boeing/Bell Helicopter XV-15 download reduction program. The key element in this program and others, where AFC technology is transitioned from small-scale laboratory tests to large-scale tests and eventually to full-scale flight, was the realization that traditional scaling parameters did not apply, and a new way of characterizing the performance of AFC was needed. This new way of thinking, where the dominant parameter is the ratio of the peak AFC jet velocity to the local flow velocity, has lead to advances in development of new AFC actuators and concepts, including Adaptive Intermittent Suction Control of Separation (AISCOS).

Kiedaisch, J.

2005-11-01

362

Active Gaze Control Improves Optic Flow-Based Segmentation and Steering  

PubMed Central

An observer traversing an environment actively relocates gaze to fixate objects. Evidence suggests that gaze is frequently directed toward the center of an object considered as target but more likely toward the edges of an object that appears as an obstacle. We suggest that this difference in gaze might be motivated by specific patterns of optic flow that are generated by either fixating the center or edge of an object. To support our suggestion we derive an analytical model that shows: Tangentially fixating the outer surface of an obstacle leads to strong flow discontinuities that can be used for flow-based segmentation. Fixation of the target center while gaze and heading are locked without head-, body-, or eye-rotations gives rise to a symmetric expansion flow with its center at the point being approached, which facilitates steering toward a target. We conclude that gaze control incorporates ecological constraints to improve the robustness of steering and collision avoidance by actively generating flows appropriate to solve the task.

Raudies, Florian; Mingolla, Ennio; Neumann, Heiko

2012-01-01

363

Energy flow and charged particle spectra in deep inelastic scattering at HERA  

NASA Astrophysics Data System (ADS)

Global properties of the hadronic final state in deep inelastic scattering events at HERA are investigated. The data are corrected for detector effects and are compared directly with QCD phenomenology. Energy flows in both the laboratory frame and the hadronic centre of mass system and energy-energy correlations in the laboratory frame are presented. Comparing various QCD models, the colour dipole model provides the only satisfactory description of the data. In the hadronic centre of mass system the momentum components of charged particles longitudinal and transverse to the virtual boson direction are measured and compared with lower energy lepton-nucleon scattering data as well as with e + e - dat from LEP.

Abt, I.; Ahmed, T.; Andreev, V.; Aid, S.; Andrieu, B.; Appuhn, R.-D.; Arpagaus, M.; Babaev, A.; Bärwolff, H.; Bán, J.; Baranov, P.; Barrelet, E.; Bartel, W.; Bassler, U.; Beck, H. P.; Behrend, H.-J.; Belousov, A.; Berger, Ch.; Bergstein, H.; Bernardi, G.; Bernet, R.; Bertrand-Coremans, G.; Besançon, M.; Biddulph, P.; Binder, E.; Bizot, J. C.; Blobel, V.; Borras, K.; Bosetti, P. C.; Boudry, V.; Bourdarios, C.; Braemer, A.; Brasse, F.; Braun, U.; Braunschweig, W.; Brisson, V.; Bruncko, D.; Büngener, L.; Bürger, J.; Büsser, F. W.; Buniatian, A.; Burke, S.; Buschhorn, G.; Campbell, A. J.; Carli, T.; Charles, F.; Chyla, J.; Clarke, D.; Clegg, A. B.; Colombo, M.; Coughlan, J. A.; Courau, A.; Coutures, Ch.; Cozzika, G.; Criegee, L.; Cvach, J.; Dagoret, S.; Dainton, J. B.; Danilov, M.; Dann, A. W. E.; Dau, W. D.; David, M.; Deffur, E.; Delcourt, B.; Del Buono, L.; Devel, M.; de Roeck, A.; di Nezza, P.; Dingus, P.; Dollfus, C.; Dowell, J. D.; Dreis, H. B.; Drescher, A.; Duboc, J.; Düllmann, D.; Dünger, O.; Duhm, H.; Ebbinghaus, R.; Eberle, M.; Ebert, J.; Ebert, T. R.; Eckerlin, G.; Efremenko, V.; Egli, S.; Ehrlichmann, H.; Eichenberger, S.; Eichler, R.; Eisele, F.; Eisenhandler, E.; Ellis, N. N.; Ellison, R. J.; Elsen, E.; Erdmann, M.; Evrard, E.; Favart, L.; Fedotov, A.; Feeken, D.; Felst, R.; Feltesse, J.; Fensome, I. F.; Ferencei, J.; Ferrarotto, F.; Flamm, K.; Flauger, W.; Fleischer, M.; Flieser, M.; Flügge, G.; Fomenko, A.; Fominykh, B.; Forbush, M.; Formánek, J.; Foster, J. M.; Franke, G.; Fretwurst, E.; Fuhrmann, P.; Gabathuler, E.; Gamerdinger, K.; Garvey, J.; Gayler, J.; Gebauer, M.; Gellrich, A.; Gennis, M.; Genzel, H.; Gerhards, R.; Godfrey, L.; Goerlach, U.; Goerlich, L.; Gogitidze, N.; Goldberg, M.; Goldner, D.; Goodall, A. M.; Gorelov, I.; Goritchev, P.; Grab, C.; Grässler, H.; Grässler, R.; Greenshaw, T.; Greif, H.; Grindhammer, G.; Gruber, A.; Gruber, C.; Haack, J.; Haidt, D.; Hajduk, L.; Hamon, O.; Hampel, M.; Hanlon, E. M.; Hapke, M.; Harjes, J.; Haydar, R.; Haynes, W. J.; Heatherington, J.; Hedberg, V.; Heinzelmann, G.; Henderson, R. C. W.; Henschel, H.; Herma, R.; Herynek, I.; Hildesheim, W.; Hill, P.; Hilton, C. D.; Hladký, J.; Hoeger, K. C.; Höppner, M.; Huet, Ph.; Hufnagel, H.; Huot, N.; Ibbotson, M.; Itterbeck, H.; Jabiol, M.-A.; Jacholkowska, A.; Jacobsson, C.; Jaffre, M.; Jansen, T.; Jönsson, L.; Johannsen, K.; Johnson, D. P.; Johnson, L.; Jung, H.; Kalmus, P. I. P.; Kant, D.; Kazarian, S.; Kaschowitz, R.; Kasselmann, P.; Kathage, U.; Kaufmann, H. H.; Kenyon, I. R.; Kermiche, S.; Keuker, C.; Kiesling, C.; Klein, M.; Kleinwort, C.; Knies, G.; Ko, W.; Köhler, T.; Kolanoski, H.; Kole, F.; Kolya, S. D.; Korbel, V.; Korn, M.; Kostka, P.; Kotelnikov, S. K.; Krasny, M. W.; Krücker, D.; Krüger, U.; Kubenka, J. P.; Küster, H.; Kuhlen, M.; Kur?a, T.; Kurzhöfer, J.; Kuznik, B.; Lacour, D.; Lamarche, F.; Lander, R.; Landon, M. P. J.; Lange, W.; Langkau, R.; Lanius, P.; Laporte, J. F.; Lebedev, A.; Leuschner, A.; Leverenz, C.; Levonian, S.; Lewin, D.; Ley, Ch.; Lindner, A.; Lindström, G.; Linsel, F.; Lipinski, J.; Loch, P.; Lohmander, H.; Lopez, G. C.; Lüers, D.; Lüke, D.; Magnussen, N.; Malinovski, E.; Mani, S.; Marage, P.; Marks, J.; Marshall, R.; Martens, J.; Martin, R.; Martyn, H.-U.; Martyniak, J.; Masson, S.; Mavroidis, A.; Maxfield, S. J.; McMahon, S. J.; Mehta, A.; Meier, K.; Mercer, D.; Merz, T.; Meyer, C. A.; Meyer, H.; Meyer, J.; Mikocki, S.; Monnier, E.; Moreau, F.; Moreels, J.; Morris, J. V.; Müller, K.; Murín, P.; Murray, S. A.; Nagovizin, V.; Naroska, B.; Naumann, Th.; Newman, P. R.; Newton, D.; Neyret, D.; Nguyen, H. K.; Niebergall, F.; Niebuhr, C.; Nisius, R.; Nowak, G.; Noyes, G. W.; Nyberg, M.; Oberlack, H.; Obrock, U.; Olsson, J. E.; Orenstein, S.; Ould-Saada, F.; Pascaud, C.; Patel, G. D.; Peppel, E.; Peters, S.; Phillips, H. T.; Phillips, J. P.; Pichler, Ch.; Pilgram, W.; Pitzl, D.; Prell, S.; Prosi, R.; Rädel, G.; Raupach, F.; Rauschnabel, K.; Reimer, P.; Reinshagen, S.; Ribarics, P.; Riech, V.; Riedlberger, J.; Riess, S.; Rietz, M.; Robertson, S. M.; Robmann, P.; Roosen, R.; Rosenbauer, K.; Rostovtsev, A.; Royon, C.; Rudowicz, M.; Ruffer, M.; Rusakov, S.; Rybicki, K.; Sahlmann, N.; Sanchez, E.; Sankey, D. P. C.; Savitsky, M.; Schacht, P.; Schleper, P.; von Schlippe, W.; Schmidt, C.; Schmidt, D.; Schmitz, W.; Schöning, A.; Schröder, V.; Schuhmann, E.; Schulz, M.; Schwab, B.; Schwind, A.; Scobel, W.; Seehausen, U.; Sell, R.; Semenov, A.; Shekelyan, V.; Sheviakov, I.; Shooshtari, H.; Shtarkov, L. N.; Siegmon, G.; Siewert, U.; Sirois, Y.; Skillicorn, I. O.; Smirnov, P.; Smith, J. R.; Soloviev, Y.; Spitzer, H.; Steenbock, M.; Steffen, P.; Steinberg, R.; Stella, B.; Stephens, K.; Stier, J.; Stösslein, U.; Strachota, J.; Straumann, U.; Struczinski, W.

1994-09-01

364

Large Eddy Simulation of Compressible Turbulent Channel Flow with Active Spanwise Wall Fluctuations  

NASA Astrophysics Data System (ADS)

The large eddy simulation (LES) of compressible turbulent channel flow controlled by active spanwise wall fluctuations (ASWF) is carried out in this paper. Heat transport and its relation with the momentum transport are paid with great attentions. In all the flow cases of present study, the changes of temperature fluctuation, heat transport and temperature streaks are in consistence with streamwise velocity fluctuation, momentum transport and velocity streaks respectively. This demonstrates the existence of same mechanism in heat transport and momentum transport in turbulent boundary layer, which gives the theoretical support for using the drag reduction technology to control wall heat flux.

Fang, Jian; Lu, Lipeng

365

Flow experience in physical activity: Examination of the internal structure of flow from a process-related perspective  

Microsoft Academic Search

Considering the phenomenology of flow experience reflects attentional processes, Nakamura and Csikszentmihalyi (Handbook of\\u000a positive psychology, Oxford University Press, New York, 2002) classified the components of flow experience into proximal conditions and the characteristics of a subjective state while\\u000a being in flow. The present study was conducted to clarify the concept of flow through examination of the interrelationships\\u000a among the

Masato KawabataClifford; Clifford J. Mallett

366

Subsonic and Supersonic shear flows in laser driven high-energy-density plasmas  

NASA Astrophysics Data System (ADS)

Shear flows arise in many high-energy-density (HED) and astrophysical systems, yet few laboratory experiments have been carried out to study their evolution in these extreme environments. Fundamentally, shear flows can initiate mixing via the Kelvin-Helmholtz (KH) instability and may eventually drive a transition to turbulence. We present two dedicated shear flow experiments that created subsonic and supersonic shear layers in HED plasmas. In the subsonic case the Omega laser was used to drive a shock wave along a rippled plastic interface, which subsequently rolled-upped into large KH vortices. In the supersonic shear experiment the Nike laser was used to drive Al plasma across a low-density foam surface also seeded with a ripple. Unlike the subsonic case, detached shocks developed around the ripples in response to the supersonic Al flow.

Harding, E. C.; Drake, R. P.; Gillespie, R. S.; Grosskopf, M. J.; Kuranz, C. C.; Visco, A.; Ditmar, J. R.; Aglitskiy, Y.; Weaver, J. L.; Velikovich, A. L.; Hurricane, O. A.; Hansen, J. F.; Remington, B. A.; Robey, H. F.; Bono, M. J.; Plewa, T.

2009-05-01

367

Groundwater flow and geochemistry in the Southeastern San Juan Basin: Implications for microbial transport and activity  

NASA Astrophysics Data System (ADS)

Recent confirmation of widespread microbial activity in the deep subsurface has raised the question whether microbes were transported to their current residence from the surface or whether they have survived in situ since sediment deposition. As a part of a larger study addressing these and related questions, we have characterized the microbiology and hydrogeology of a Late Cretaceous sandstone and shale sequence in the southeastern San Juan Basin New Mexico, near a 3.39 Ma volcanic intrusion. Deep core samples were analyzed for microbial activity to assess recolonization of the previously sterilized zone around the intrusion. Groundwater geochemistry and isotopic data were used to improve the understanding of the flow regime. We modeled the geochemical evolution of the groundwater from the recharge area to each sample location and used the resultant mass transfers to correct measured 14C activities. The 14C ages provided the basis for calibrating a cross-sectional flow model that intersects the intrusion. Based on microbial activity data, hydrogeologic modeling results supported the inference that groundwater velocities were adequate to transport microbes into the previously sterilized region in the time since the volcanic intrusion. Evidence of upward groundwater flow near the intrusion and high vertical hydraulic conductivities for shale suggest considerable hydraulic connection between lithologie units, which may influence the nutrient distribution and promote enhanced microbial activity near lithologic interfaces.

Walvoord, Michelle A.; Pegram, Page; Phillips, Fred M.; Person, Mark; Kieft, Thomas L.; Fredrickson, James K.; McKinley, James P.; Swenson, John B.

1999-05-01

368

Differentiation of borreliacidal activity caused by immune serum or antimicrobial agents by flow cytometry.  

PubMed Central

We demonstrated that borreliacidal activity caused by immune serum and complement can easily be differentiated by flow cytometry from killing activity caused by antimicrobial agents that are commonly used for the treatment of Lyme disease. Assay suspensions containing normal or immune serum were incubated with Borrelia burgdorferi in the presence or absence of ceftriaxone, doxycycline, penicillin, and phosphomycin for 2, 8, 16, and 24 h. Samples containing killing activity were identified by using flow cytometry and acridine orange. In 30 min, the effects of immune serum and complement were easily distinguished from the killing of spirochetes by antimicrobial agents by adding fluorescein isothiocyanate-conjugated goat anti-hamster immunoglobulin. This simple procedure greatly enhanced the usefulness of the borreliacidal assay by eliminating a major source of false-positive reactions.

Liu, Y F; Lim, L C; Schell, K; Lovrich, S D; Callister, S M; Schell, R F

1994-01-01

369

The Rate of Change of the Kinetic Energy Spectrum of Flow in a Compressible Fluid  

Microsoft Academic Search

The variance spectrum of velocities in a non-homogeneous, compressible fluid does not represent the wave-number distribution of kinetic energy, as it does in incompressible, homogeneous (constant density) fluids. Use of a truncated Fourier transform and the assumption that the flow occurs in a finite area show that the kinetic energy spectrum in the former case is the co-spectrum between the

John A. Dutton

1963-01-01

370

Activation energies for gas-phase dissociations of multiply charged ions from electrospay ionization mass spectrometry  

SciTech Connect

The reactions of multiply protonated melittin molecular ions of various charge states produced from an electrospray ionization source have been studied. The flow of ions entrained in gas through a heated metal capillary inlet serves as a reaction vessel for gas-phase measurements of molecular ion reaction rates using mass spectrometry. Activation energies for the unimolecular dissociation reactions are calculated from the temperature dependence of the reaction kinetics. The differences in activation energies for the reactions of the different charge states are attributed to the destabilizing effect of Coulombic repulsion for high charged ions. 18 refs., 3 figs., 1 tab.

Busman, M.; Rockwood, A.L.; Smith, R.D. [Pacific Northwest Lab., Richland, WA (United States)

1992-03-19

371

Numerical Simulation on the Continuous Operation of an Aquifer Thermal Energy Storage System Under Regional Groundwater Flow  

Microsoft Academic Search

A three-dimensional numerical model for groundwater flow and heat transport is used to analyze an aquifer thermal energy storage system operating under a continuous flow regime. This study emphasizes the influence of regional groundwater flow on the performance of the system under various operation scenarios. The pressure gradient across the system, which determines the direction and velocity of regional groundwater

K. S. Lee

2011-01-01

372

Measurement of anisotropic energy transport in flowing polymers by using a holographic technique.  

PubMed

Almost no experimental data exist to test theories for the nonisothermal flow of complex fluids. To provide quantitative tests for newly proposed theories, we have developed a holographic grating technique to study energy transport in an amorphous polymer melt subject to flow. Polyisobutylene with weight-averaged molecular mass of 85 kDa is sheared at a rate of 10 s(-1), and all nonzero components of the thermal conductivity tensor are measured as a function of time, after cessation. Our results are consistent with proposed generalizations to the energy balance for microstructural fluids, including a generalized Fourier's law for anisotropic media. The data are also consistent with a proposed stress-thermal rule for amorphous polymer melts. Confirmation of the universality of these results would allow numerical modelers to make quantitative predictions for the nonisothermal flow of polymer melts. PMID:15340152

Schieber, Jay D; Venerus, David C; Bush, Kendall; Balasubramanian, Venkat; Smoukov, Stoyan

2004-08-30

373

Energy-transformation properties and mechanisms in transverse-flow-discharged CO2 lasers  

SciTech Connect

We simulated, calculated, and analyzed the effects on the various energy state transformation properties of dielectric media of such factors as dielectric media gas pressures, flow speeds, light cavity position, strength of radiation in the cavity, degree of output coupling, and other similar factors in transverse flow discharged CO2 laser devices. This article did concrete calculations of the corresponding energy transformation properties for the apparatus and the conditions in reference (transverse flow, discharge, CO2 laser device, dielectric medium constituent ratio of CO2:N2:H = 5:17:78, an initial temperature of 293K, a discharge current of 2A, E/N: 2.15X10-16 V/cm2, light cavity 160 cm2 long, height 1.8cm, as well as other parameters).

Zhongxiang, W.

1991-12-10

374

Diversion of energy flow near crack tips of a vibrating plate using the structural intensity technique  

NASA Astrophysics Data System (ADS)

The structural intensity (SI) of a vibrating rectangular plate with a crack is computed using the finite element method. The overall behavior of power flow patterns of the cracked plate is investigated. The presence of the crack can be identified by the changes of the directions of SI vectors near the crack. The effects of orientation of the crack and crack length on the energy flow pattern are also investigated. The SI method is then used to explore the positioning of dampers in vibrating thin plates to divert the vibration energy flow away from crack tips. This approach is proposed as a temporary measure to prevent further propagation of the crack before repair of the crack can be done.

Lee, H. P.; Lim, S. P.; Khun, M. S.

2006-09-01

375

Flow dependence of high p{sub T} parton energy loss in heavy-ion collisions  

SciTech Connect

The measured transverse momentum spectra and HBT correlations of bulk (i.e., low p{sub T}) matter can be well explained by assuming that the soft sector of particles produced in ultrarelativistic heavy-ion collisions is (approximately) thermalized and undergoes collective accelerated expansion in both longitudinal and transverse direction. However, this implies that bulk matter will have a nonvanishing flow component transverse to the trajectory of a high p{sub T} partonic jets. In general, this will increase the energy loss experienced by the jet parton and modify the shape of the jet cone. In this paper, we present a systematic study of the magnitude of the additional energy loss induced by flow under realistic assumptions for the medium evolution. We argue that a perturbative QGP description may be sufficient for the measured R{sub AA} if flow during the medium evolution is taken into account properly.

Renk, Thorsten; Ruppert, Joerg [Department of Physics, Duke University, P.O. Box 90305, Durham, North Carolina 27708 (United States)

2005-10-01

376

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

377

World Energy Projection System Plus (WEPS+): Global Activity Module  

EIA Publications

World Energy Projection System Plus Model Documentation: Global Activity Module Documents the objectives, analytical approach, and development of the World Energy Projection Plus (WEPS+) Global Activity Module (GAM) used to develop the International Energy Outlook for 2013 (IEO2013). The report catalogues and describes the module assumptions, computations, methodology, parameter estimation techniques, and mainframe source code

Vipin Arora

2013-10-23

378

Simulation of activation free energies in molecular systems  

Microsoft Academic Search

A method is presented for determining activation free energies in complex molecular systems. The method relies on knowledge of the minimum energy path and bases the activation free energy calculation on moving along this path from a minimum to a saddle point. Use is made of a local reaction coordinate which describes the advance of the reaction in each segment

Eyal Neria; Stefan Fischer; Martin Karplus

1996-01-01

379

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

380

Energy conversion systems utilizing two-phase flow liquid metal MHD generators and compressors  

Microsoft Academic Search

The application of liquid metal MHD energy-conversion technology over a wide spectrum of electric power and refrigeration systems has been analyzed. Different concepts utilizing this technology have been put forward, and a number have been tested. Complete systems were configured free of rotating machinery. Further simplifications resulted in systems free of two-phase flow mixing and separating devices, with some systems

A. El-Boher; L. Blumenau; H. Branover; E. Spero; S. Sukoriansky

1987-01-01

381

Optimal energy amplification of plane turbulent channel flows with emphasis on different types of perturbation  

Microsoft Academic Search

Optimal perturbations in turbulent channel flow with mean velocity profile and its associated eddy viscosity are investigated, with emphasis on different types of perturbation. We look for linear amplification of both very large-scale outer structures and near-wall streaks arising from three types of perturbations: initial perturbation, harmonic forcing and stochastic excitation. Proper premultiplied energy amplification factors for optimal harmonic forcing

Yongyun Hwang; Ashley Willis; Carlo Cossu

2009-01-01

382

Observation of Saturation of Energy Transfer between Copropagating Beams in a Flowing Plasma  

Microsoft Academic Search

Experiments demonstrate energy and power transfer between copropagating, same frequency, beams crossing at a small angle in a plasma with a Mach1 flow. The process is interpreted as amplification of the low intensity probe beam by the stimulated scatter of the high intensity pump beam. The observed probe amplification increases slowly with pump intensity and decreases with probe intensity, indicative

R. K. Kirkwood; J. D. Moody; A. B. Langdon; B. I. Cohen; E. A. Williams; M. R. Dorr; J. A. Hittinger; R. Berger; P. E. Young; L. J. Suter; L. Divol; S. H. Glenzer; O. L. Landen; W. Seka

2002-01-01

383

Damping of transient energy growth of three-dimensional perturbations in hydromagnetic pipe flow  

Microsoft Academic Search

The stability of infinitesimal three-dimensional perturbations in hydromagnetic pipe flow where the applied magnetic field is in the streamwise direction is considered. The study is limited to the case of small magnetic Reynolds numbers and the main objective of the paper is to study the transient evolution of the kinetic energy. A general effect of the magnetic field is to

Hans O. Åkerstedt

1995-01-01

384

Decibel error test and flow law of multiphase rocks based on energy dissipation theory  

Microsoft Academic Search

A new flow law is developed based on energy dissipation theory, which is independent of bound theory. The influence of the distribution of constituent minerals on the rheological behavior of the rock is taken into account and expressed as an additional continuity condition in the theory instead of the lower and upper bounds in bound theory. With the continuity equations,

Yan Jiang; Shaoxian Zang; Rongqiang Wei

2005-01-01

385

Problem of Energy Transfer in Centrifugal and Mixed-Flow Pumps by Circulation and Coriolis Forces.  

National Technical Information Service (NTIS)

An analysis is presented of some problems of designing centrifugal and mixed-flow pumps from the point of view of the energy transfer processes. It was previously shown (Ovsyannikov, B. V., Aviatsionnaya tekhnika, no. 2, 1963) that in a centrifugal pump t...

B. V. Ovsyannikov B. I. Borovskii

1968-01-01

386

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

Microsoft Academic Search

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

Jacek Majorowicz; Stephen E. Grasby

2010-01-01

387

Application of the energy flow method to vibration control of buildings with multiple tuned liquid dampers  

Microsoft Academic Search

The energy flow method is used to study the vibrations of tall buildings coupled to rectangular tanks as vibration absorbers and also for a primary structure coupled to a rotary tuned liquid column damper. The tall building is studied using the receptance approach, with harmonic and wind loads. The formulation deals with one beam simulating the building, coupled to many

K. Shankar; T. Balendra

2002-01-01

388

Radial particle flow, electrical conductivity and thermal energy content in the Frascati Tokamak Upgrade  

Microsoft Academic Search

Experimental determinations of the radial plasma flow velocity, of Zeff and of the thermal energy content, made on the Frascati Tokamak Upgrade (FTU), have been compared with the predictions of the conventional neoclassical theory, of the extended neoclassical theory and of the pseudoneoclassical theory. In the comparison only the momentum balance and continuity equations were used. The best overall agreement

G. Bracco; S. E. Segre; V. Zanza; G. Apruzzese; F. Bombarda; P. Buratti; F. Crisanti; R. de Angelis; D. Frigione; L. Gabellier; M. Grolli; H. Kroegler; G. Mazzitelli; D. H. McNeill; A. Moleti; S. Podda; M. Zerbini

1994-01-01

389

In silico approaches to study mass and energy flows in microbial consortia: a syntrophic case study  

Microsoft Academic Search

BACKGROUND: Three methods were developed for the application of stoichiometry-based network analysis approaches including elementary mode analysis to the study of mass and energy flows in microbial communities. Each has distinct advantages and disadvantages suitable for analyzing systems with different degrees of complexity and a priori knowledge. These approaches were tested and compared using data from the thermophilic, phototrophic mat

Reed Taffs; John E Aston; Kristen Brileya; Zackary Jay; Christian G Klatt; Shawn McGlynn; Natasha Mallette; Scott Montross; Robin Gerlach; William P Inskeep; David M Ward; Ross P Carlson

2009-01-01

390

Active control of the flow behind a two-dimensional bluff body in ground proximity  

NASA Astrophysics Data System (ADS)

Active flow control around a two-dimensional geometry positioned near the ground is experimentally studied. Results for two model configurations are reported: one square-back and the other with a flap added at the rear-corner. The model rear end static pressure and the near-wake flow properties are derived from wall-pressure measurements, high-speed Particle Image Velocimetry acquisitions and hot-wire anemometry. The control flow is obtained from a pulsed jet system driven in open loop. The study aims at distinguishing the individual influence of the passive flap and the control system. The actuation frequency is shown to be a determining parameter regarding rear end pressure increase.

Chaligné, Sébastien; Castelain, Thomas; Michard, Marc; Juvé, Daniel

2013-03-01

391

Flow limitation and regulation of functional residual capacity during exercise in a physically active aging population.  

PubMed

In 29 older (69 +/- 1 yr), physically active subjects (VO2max = 44 +/- 2 ml.kg-1.min-1), we determined the effect of an age-related decline in elastic lung recoil (i.e., Vmax50 = 65% of 30-yr-old adults) on the ventilatory response to progressive exercise. More specifically, we assessed if expiratory airflow limits were achieved and how this may modulate the regulation of end-expiratory lung volume (EELV). We found that with only mild to moderate (50 to 75% VO2max) exercise, the mean EELV was reduced 0.38 +/- 0.07 L, and that expiratory flow limitation was present over 25 +/- 4% of the VT. In 11 subjects during this intensity of exercise, EELV was within their closing capacity. As exercise intensity progressed, VT plateaued at 58 +/- 2% of the vital capacity, and increased expiratory air flow rates were achieved by significantly increasing the EELV back to near resting levels, thereby moving a portion of the expiratory tidal flow-volume envelope away from the constraints of the effort independent portion of the maximal flow-volume curve. During heavy exercise, end-inspiratory lung volume (EILV) approached 90% of TLC. To achieve greater expiratory flow with maximal exercise, EELV remained similar to the previous intensity, and a significantly greater portion of the tidal expiratory flow-volume envelope (greater than 40% of the VT) became flow-limited. Despite this significant expiratory limitation, a rise in EELV, and an EILV approaching TLC, TI/Ttot remained constant throughout exercise, and the ventilatory response for the metabolic demand (VA/VCO2) was appropriate.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:2024851

Johnson, B D; Reddan, W G; Pegelow, D F; Seow, K C; Dempsey, J A

1991-05-01

392

Conductive heat flow at the TAG Active Hydrothermal Mound: Results from 1993-1995 submersible surveys  

NASA Astrophysics Data System (ADS)

We report 70 measurements of conductive heat flow at the 50-m-high, 200-m-diameter TAG active hydrothermal mound, made during submersible surveys with Alvin in 1993 and 1995 and Shinkai 6500 in 1994. The stations were all measured with 5-thermistor, 0.6- or 1-m-long Alvin heat flow probes, which are capable of determining both gradient and thermal conductivity, and were transponder-navigated to an estimated accuracy of ±5-10 m relative to the 10-m-diameter central complex of black smokers. Within 20 m of this complex, conductive heat flow values are extremely variable (0.1- > 100 W/m²), which can only be due to local spatial and possible temporal variability in the immediate vicinity of the vigorous discharge sites. A similar local variability is suggested in the “Kremlin” area of white smokers to the southeast of the black smoker complex. On the south and southeast side of the mound, there is very high heat flow (3.7- > 25 W/m²) on the sedimented terraces that slope down from the Kremlin area. Heat flow is also high (0.3-3 W/m²) in the pelagic carbonate sediments on the surrounding seafloor within a few tens of meters of the southwest, northwest, and northeast sides of the mound. On the west side of the sulfide rubble plateau that surrounds the central black smoker peak, there is a coherent belt of very low heat flow (<20 mW/m²) 20-50 m west of the smokers, suggestive of local, shallow recharge of bottom water. The three submersible surveys spanned nearly two years, but showed no indication of any temporal variability in conductive heat flow over this time scale, whether natural or induced by ODP drilling in 1994.

Becker, K.; Von Herzen, R.; Kirklin, J.; Evans, R.; Kadko, D.; Kinoshita, M.; Matsubayashi, O.; Mills, R.; Schultz, A.; Rona, P.

393

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.

394

Energy Conservation Activity Packet, Grade 4. Revised Edition.  

ERIC Educational Resources Information Center

This activity notebook for grade 4 is one in a series developed in response to the concern for energy conservation. It contains activities that stress an energy conservation ethic and includes many values clarification activities for grade four. The packet is divided into two parts and provides the teacher with background information, concepts and…

Pohlman, Betty; And Others

395

Energy Conservation Activity Packet, Grade 5. Revised Edition.  

ERIC Educational Resources Information Center

This activity notebook for grade 5 is one of a series developed in response to energy conservation. It contains activities that stress an energy conservation ethic and includes many values clarification activities for grade five. The packet is divided into two parts and provides the teacher with background information, concepts and objectives, and…

Pohlman, Betty; And Others

396

Experimental Studies of Active and Passive Flow Control Techniques Applied in a Twin Air-Intake  

PubMed Central

The flow control in twin air-intakes is necessary to improve the performance characteristics, since the flow traveling through curved and diffused paths becomes complex, especially after merging. The paper presents a comparison between two well-known techniques of flow control: active and passive. It presents an effective design of a vortex generator jet (VGJ) and a vane-type passive vortex generator (VG) and uses them in twin air-intake duct in different combinations to establish their effectiveness in improving the performance characteristics. The VGJ is designed to insert flow from side wall at pitch angle of 90 degrees and 45 degrees. Corotating (parallel) and counterrotating (V-shape) are the configuration of vane type VG. It is observed that VGJ has the potential to change the flow pattern drastically as compared to vane-type VG. While the VGJ is directed perpendicular to the side walls of the air-intake at a pitch angle of 90 degree, static pressure recovery is increased by 7.8% and total pressure loss is reduced by 40.7%, which is the best among all other cases tested for VGJ. For bigger-sized VG attached to the side walls of the air-intake, static pressure recovery is increased by 5.3%, but total pressure loss is reduced by only 4.5% as compared to all other cases of VG.

Joshi, Shrey; Jindal, Aman; Maurya, Shivam P.; Jain, Anuj

2013-01-01

397

Radial flow has little effect on clusterization at intermediate energies in the framework of the lattice gas model  

SciTech Connect

The lattice gas model was extended to incorporate the effect of radial flow. Contrary to popular belief, radial flow has little effect on the clusterization process in intermediate energy heavy-ion collisions except adding an ordered motion to the particles in the fragmentation source. We compared the results from the lattice gas model with and without radial flow to experimental data. We found that charge yields from central collisions are not significantly affected by inclusion of any reasonable radial flow.

Das, C.B. [Physics Department, McGill University, Montreal, H3A 2T8 (Canada); Physics Division, Variable Energy Cyclotron Center, 1/AF Bidhannagar, Kolkata 700 064 (India); Shi, L.; Gupta, S. Das [Physics Department, McGill University, Montreal, H3A 2T8 (Canada)

2004-12-01

398

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

399

Modular bioreactor for primary human hepatocyte culture: Medium flow stimulates expression and activity of detoxification genes  

PubMed Central

Down-regulation of detoxification genes, notably cytochrome P450 (CYPs), in primary hepatocyte cultures is a long-standing and major concern. We evaluated the influence of medium flow in this model. Hepatocytes isolated from 12 different liver donors were cultured either in a multichamber modular bioreactor (MCmB, flow rate 250–500 ?L/min) or under standard/static conditions, and the expression of 32 genes, enzyme activities and biological parameters were measured 7–21 days later. mRNA expression of genes involved in xenobiotic/drug metabolism and transport, including CYP1A1, 1A2, 2B6, 2C9, 3A4 (and activities for some of them), UDP-glucuronosyltransferase (UGT) 1A1, UGT2B4, UGT2B7, glutathione S-transferase (GST?), and multidrug resistance protein 1 (MDR1) and MRP2, were specifically up-regulated by medium flow as compared with static controls in all cultures tested. In 2-week-old cultures, expression of detoxification genes reached levels close to or higher than those measured in freshly isolated hepatocytes. In contrast, CYP2D6 and most of other tested genes were not affected by medium flow. We conclude that medium flow specifically interferes with, and up-regulates, the activity of xenosensors and/or the expression of detoxification genes in primary human hepatocytes. Down-regulation of detoxification genes in conventional (static) cultures is therefore partly a consequence of the absence of medium circulation.

Vinci, Bruna; Duret, Cedric; Klieber, Sylvie; Gerbal-Chaloin, Sabine; Sa-Cunha, Antonio; Laporte, Sylvain; Suc, Bertrand; Maurel, Patrick; Ahluwalia, Arti; Daujat-Chavanieu, Martine

2011-01-01

400

Leg blood flow during submaximal cycle ergometry is not reduced in healthy older normally active men.  

PubMed

The purpose of the present study was to test the hypothesis that leg blood flow responses during submaximal cycle ergometry are reduced with age in healthy normally active men. Eleven younger (20-25 yr) and eight older (62-73 yr) normotensive, nonendurance-trained men performed both graded and constant-load bouts of leg cycling at the same absolute and relative [% of peak O(2) consumption (Vo(2 peak))] exercise intensities while leg blood flow (femoral vein thermodilution), mean arterial pressure (MAP; radial artery), cardiac output (acetylene rebreathing), blood O(2) content, and plasma catecholamines were measured. Leg blood flow responses at the same absolute submaximal power outputs (20-100 W) and at a fixed systemic O(2) demand (1.1 l/min) did not differ between groups (P = 0.14-0.19), despite lower absolute levels of cardiac output in the older men (P < 0.05). MAP at the same absolute power outputs was 8-12 mmHg higher (P < 0.05) in the older men, but calculated leg vascular conductance responses (leg blood flow/MAP) were identical in the two groups (P > 0.9). At the same relative intensity (60% Vo(2 peak)), leg norepinephrine spillover rates were approximately twofold higher in the older men (P = 0.38). Exercise-induced increases in leg arterial-venous O(2) difference were identical between groups (P > 0.9) because both arterial and venous O(2) contents were lower in the older vs. younger men. These results suggest that the ability to augment active limb blood flow and O(2) extraction during submaximal large muscle mass exercise is not impaired but is well preserved with age in healthy men who are normally active. PMID:12547841

Proctor, David N; Newcomer, Sean C; Koch, Dennis W; Le, Khoi U; MacLean, David A; Leuenberger, Urs A

2003-01-24

401

Salivary Alpha-Amylase Activity and Salivary Flow Rate in Young Adults  

PubMed Central

The secretion of salivary alpha-amylase (sAA) is more associated with psychoneuroendocrinological response to stress than with the flow rate and age. The aim of this cross sectional study is to build an explanatory model based on patterns of relationship between age 20-39 in resting and stimulated saliva under no stressful condition in healthy volunteers. Both resting and stimulated saliva were collected from 40 subjects. The sAA values were log-transformed, the normality assumption was verified with the Shapiro-Wilk test and the reliability of the measurements was estimated by the Pearsons’ r correlation coefficient. The estimated model was based on the theory of the Linear Mixed Models. Significant mean changes were observed in flow rate and sAA activity between resting and stimulated saliva. The final model consists of two components, the first revealed a positive correlation between age and sAA while the second one revealed a negative correlation between the interaction of age × flow rate in its condition (resting or stimulated saliva), with sAA. Both flow rate and age influence sAA activity.

Arhakis, Aristidis; Karagiannis, Vasilis; Kalfas, Sotirios

2013-01-01

402

Active control of vortex induced vibrations for flow past a circular cylinder  

NASA Astrophysics Data System (ADS)

The flow past rigid bodies which are flexibly mounted would experience vortex induced oscillations. The phenomenon of eddy shedding is responsible for the asymmetric force distribution on the cylinder. In a variety of natural and technological applications, these vortex induced oscillations may cause resonance and structural failure [1]. Controlling vortex shedding by active annihilation of the wake vortices is of interest in flow control studies [2]. An active closed loop feedback control algorithm is designed and implemented for controlling the flow induced oscillations in the circular cylinder. Admissible acting functions are incorporated in the form of rotating control cylinders. The control algorithm is designed and integrated along with the equations for mass,momentum transport. The state of the flow is reported through multiple sensors and the quantum of actuations is performed by the controllers as dictated by the control algorithm. Present simulations are carried out at low Reynolds number, 100 and 200, and the complete suppression of self-excited oscillations is observed.[4pt] [1] Williamson C.H.K. and Govardhan R., Ann. Rev. Fluid Mech., 36, 413-455, (2004). [0pt] [2] Muddada S. and Patnaik B.S.V., Eur. J. Mech. B - Fluids, 29, 93 - 104 ,(2010).

Sridhar, M.; Patnaik, B. S. V.

2010-11-01

403

Salivary alpha-amylase activity and salivary flow rate in young adults.  

PubMed

The secretion of salivary alpha-amylase (sAA) is more associated with psychoneuroendocrinological response to stress than with the flow rate and age. The aim of this cross sectional study is to build an explanatory model based on patterns of relationship between age 20-39 in resting and stimulated saliva under no stressful condition in healthy volunteers. Both resting and stimulated saliva were collected from 40 subjects. The sAA values were log-transformed, the normality assumption was verified with the Shapiro-Wilk test and the reliability of the measurements was estimated by the Pearsons' r correlation coefficient. The estimated model was based on the theory of the Linear Mixed Models. Significant mean changes were observed in flow rate and sAA activity between resting and stimulated saliva. The final model consists of two components, the first revealed a positive correlation between age and sAA while the second one revealed a negative correlation between the interaction of age × flow rate in its condition (resting or stimulated saliva), with sAA. Both flow rate and age influence sAA activity. PMID:23524385

Arhakis, Aristidis; Karagiannis, Vasilis; Kalfas, Sotirios

2013-02-22

404

Flow-induced platelet activation in bileaflet and monoleaflet mechanical heart valves.  

PubMed

A study was conducted to measure in vitro the procoagulant properties of platelets induced by flow through Carbomedics bileaflet and Bjork-Shiley monoleaflet mechanical heart valves (MHVs). Valves were mounted in a left ventricular assist device, and platelets were circulated through them under pulsatile flow. Platelet activation states (PAS) were measured during circulation using a modified prothrombinase method. Computational fluid dynamics (CFD) simulations of turbulent, transient, and non-Newtonian blood flow patterns generated by the two valve designs were done using the Wilcox k - w turbulence model, and platelet shear-stress histories (the integral of shear-stress exposure with respect to time) through the two MHVs were calculated. PAS measurements indicated that the bileaflet MHV activated platelets at a rate more than twice that observed with the monoleaflet MHV. Turbulent flow patterns were evident in CFD simulations for both valves, and corroborated the PAS observations, showing that, for particles close to the leaflet(s), shear-stress exposure in the bileaflet MHV can be more than four times that in the monoleaflet valve. PMID:15446502

Yin, Wei; Alemu, Yared; Affeld, Klaus; Jesty, Jolyon; Bluestein, Danny

2004-08-01

405

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

406

Reduced order modeling and active flow control of an inlet duct  

NASA Astrophysics Data System (ADS)

Many aerodynamic applications require the modeling of compressible flows in or around a body, e.g., the design of aircraft, inlet or exhaust duct, wind turbines, or tall buildings. Traditional methods use wind tunnel experiments and computational fluid dynamics (CFD) to investigate the spatial and temporal distribution of the flows. Although they provide a great deal of insight into the essential characteristics of the flow field, they are not suitable for control analysis and design due to the high physical/computational cost. Many model reduction methods have been studied to reduce the complexity of the flow model. There are two main approaches: linearization based input/output modeling and proper orthogonal decomposition (POD) based model reduction. The former captures mostly the local behavior near a steady state, which is suitable to model laminar flow dynamics. The latter obtains a reduced order model by projecting the governing equation onto an "optimal" subspace and is able to model complex nonlinear flow phenomena. In this research we investigate various model reduction approaches and compare them in flow modeling and control design. We propose an integrated model-based control methodology and apply it to the reduced order modeling and active flow control of compressible flows within a very aggressive (length to exit diameter ratio, L/D, of 1.5) inlet duct and its upstream contraction section. The approach systematically applies reduced order modeling, estimator design, sensor placement and control design to improve the aerodynamic performance. The main contribution of this work is the development of a hybrid model reduction approach that attempts to combine the best features of input/output model identification and POD method. We first identify a linear input/output model by using a subspace algorithm. We next project the difference between CFD response and the identified model response onto a set of POD basis. This trajectory is fit to a nonlinear dynamical model to augment the linear input/output model. Thus, the full system is decomposed into a dominant linear subsystem and a low order nonlinear subsystem. The hybrid model is then used for control design and compared with other modeling methods in CFD simulations. Numerical results indicate that the hybrid model accurately predicts the nonlinear behavior of the flow for a 2D diffuser contraction section model. It also performs best in terms of feedback control design and learning control. Since some outputs of interest (e.g., the AIP pressure recovery) are not observable during normal operations, static and dynamic estimators are designed to recreate the information from available sensor measurements. The latter also provides a state estimation for feedback controller. Based on the reduced order models and estimators, different controllers are designed to improve the aerodynamic performance of the contraction section and inlet duct. The integrated control methodology is evaluated with CFD simulations. Numerical results demonstrate the feasibility and efficacy of the active flow control based on reduced order models. Our reduced order models not only generate a good approximation of the nonlinear flow dynamics over a wide input range, but also help to design controllers that significantly improve the flow response. The tools developed for model reduction, estimator and control design can also be applied to wind tunnel experiment.

Ge, Xiaoqing

407

Wave energy and wave-induced flow reduction by full-scale model Posidonia oceanica seagrass  

NASA Astrophysics Data System (ADS)

This paper presents results from experiments in a large flume on wave and flow attenuation by a full-scale artificial Posidonia oceanica seagrass meadow in shallow water. Wave height and in-canopy wave-induced flows were reduced by the meadow under all tested regular and irregular wave conditions, and were affected by seagrass density, submergence and distance from the leading edge. The energy of irregular waves was reduced at all components of the spectra, but reduction was greater at the peak spectral frequency. Energy dissipation factors were largest for waves with small orbital amplitudes and at low wave Reynolds numbers. An empirical model, commonly applied to predict friction factors by rough beds, proved applicable to the P. oceanica bed. However at the lowest Reynolds numbers, under irregular waves, the data deviated significantly from the model. In addition, the wave-induced flow dissipation in the lower canopy increased with increasing wave orbital amplitude and increasing density of the mimics. The analysis of the wave-induced flow spectra confirm this trend: the reduction of flow was greatest at the longer period component of the spectra. Finally, we discuss the implications of these findings for sediment dynamics and the role of P. oceanica beds in protecting the shore from erosion.

Manca, E.; Cáceres, I.; Alsina, J. M.; Stratigaki, V.; Townend, I.; Amos, C. L.

2012-12-01

408

Relationships between available potential energy, kinetic energy, and extratropical cyclone activity within east coast cyclogenetic regions  

Microsoft Academic Search

Interrelationships between the available potential energy and kinetic energy associated with extratropical cyclones are examined for portions of the First GARP Global Experiment (FGGE) year. The study is confirmed to the cyclogenetically active regions encompassing the eastern coasts of Asia and North America. Calculations of vertically integrated available potential energy (APE) and kinetic energy (KE) are done for an active

John V. Zapotocny

1987-01-01

409

Wellbore flow characteristics for optimal energy recovery from Gulf Coast geopressured geothermal sources  

NASA Astrophysics Data System (ADS)

Geopressured geothermal brines contain potential energy in three forms: dissolved methane, high pressure, and high temperature. For optimal resource utilization one must separate the natural gas while simultaneously maximizing the conversion processes required for the liquid phase. The present paper discusses some basic thermodynamic concepts which determine the conversion effectiveness of hydraulic and thermal energy components. Using realistic resource data for Texas and Louisiana, it is shown that there is a range of well flow rates which maximizes the brine energy recovery. The effects of salinity levels on various flow parameters are also illustrated; in general, salinity is found to have a minor effect on theoretical performance. Hence, the major influence of dissolved solids would be on equipment performance.

Lamb, J. P.; Hamburger, C. L.

1981-01-01

410

Change in the regimes of flow and combustion in a channel under external energy action  

NASA Astrophysics Data System (ADS)

The influence of the energy impulse-periodic action on the structure of the hydrogen-air mixture flow in a channel for going from the regime of diffusion combustion of the mixture to pseudojump-like combustion has been investigated. Experiments were carried out in a rectangular channel with sections of variable and constant cross-section. The energy input was controlled with the aid of a heat-gas-dynamic pulse generator in which a hydrogen-air mixture was burned. The intensity and regimes of combustion were determined by the flame radiation in the ultraviolet spectral region and static pressure measurements. In the course of experiments, the possibility of going from diffusion to pseudojump-like combustion under periodic energy and kinetic actions on the mixture flow has been confirmed.

Zabaikin, V. A.; Naumov, I. E.; Tret'yakov, P. K.

2012-11-01

411

Nanoscale fluid-structure interaction: Flow resistance and energy transfer between water and carbon nanotubes  

NASA Astrophysics Data System (ADS)

We investigate here water flow passing a single-walled carbon nanotube (CNT), through analysis based on combined atomistic and continuum mechanics simulations. The relation between drag coefficient CD and Reynolds number Re is obtained for a wide range of flow speed u from 5 to 600 m/s. The results suggest that Stokes law for creep flow works well for small Reynolds numbers up to 0.1 (u ? 100 m/s), and indicates a linear dependence between drag force and flow velocity. Significant deviation is observed at elevated Re values, which is discussed by considering the interfacial slippage, reduction of viscosity due to friction-induced local heating, and flow-induced structural vibration. We find that interfacial slippage has a limited contribution to the reduction of the resistance, and excitations of low-frequency vibration modes in the carbon nanotube play an important role in energy transfer between water and carbon nanotubes, especially at high flow speeds where drastic enhancement of the carbon nanotube vibration is observed. The results reported here reveal nanoscale fluid-structure interacting mechanisms, and lay the ground for rational design of nanofluidics and nanoelectromechanical devices operating in a fluidic environment.

Chen, Chao; Ma, Ming; Jin, Kai; Liu, Jefferson Zhe; Shen, Luming; Zheng, Quanshui; Xu, Zhiping

2011-10-01

412

Evaluation of Turbulence Kinetic Energy Budget in Turbulent Flows by Using Photobleaching Molecular Tagging Velocimetry  

NASA Astrophysics Data System (ADS)

Understanding turbulence kinetic energy (TKE) budget in gas-liquid two-phase bubbly flows is indispensable to develop and improve turbulence models for the bubbly flows. Simultaneous measurement of velocity and velocity gradients with a spatial resolution smaller than the Kolmogorov scale is required to evaluate the TKE budget experimentally. We therefore proposed a molecular tagging velocimetry based on photobleaching reaction (PB-MTV) and applied it to turbulent flows in a square duct to demonstrate the possibility of evaluation of TKE budget. In this study, we improved PB-MTV in its processing speed by utilizing GPGPU (General Purpose Graphic Processing Unit) to increase sample number in measurements. We measured TKE budget in a turbulent water flow in a square duct by using the PB-MTV at the same turbulent Reynolds number as DNS data provided by Horiuti, and compared the measured data with the DNS data to validate PB-MTV for evaluation of TKE budget. We also measured TKE budget in a bubbly flow in the square duct to examine effects of bubbles on TKE budget. As a result, we found that (1) PB-MTV can accurately evaluate TKE budget in turbulent flows, (2) bubbles affect the production and diffusion rates of TKE and do not affect the dissipation rate so much, and (3) the model proposed by Troshko and Hassan can reasonably estimate the production rate of the bubble-induced pseudo turbulence.

Hosokawa, Shigeo; Mizumoto, Hiroki; Tomiyama, Akio

413

Nanoscale fluid-structure interaction: flow resistance and energy transfer between water and carbon nanotubes.  

PubMed

We investigate here water flow passing a single-walled carbon nanotube (CNT), through analysis based on combined atomistic and continuum mechanics simulations. The relation between drag coefficient C(D) and Reynolds number Re is obtained for a wide range of flow speed u from 5 to 600 m/s. The results suggest that Stokes law for creep flow works well for small Reynolds numbers up to 0.1 (u ? 100 m/s), and indicates a linear dependence between drag force and flow velocity. Significant deviation is observed at elevated Re values, which is discussed by considering the interfacial slippage, reduction of viscosity due to friction-induced local heating, and flow-induced structural vibration. We find that interfacial slippage has a limited contribution to the reduction of the resistance, and excitations of low-frequency vibration modes in the carbon nanotube play an important role in energy transfer between water and carbon nanotubes, especially at high flow speeds where drastic enhancement of the carbon nanotube vibration is observed. The results reported here reveal nanoscale fluid-structure interacting mechanisms, and lay the ground for rational design of nanofluidics and nanoelectromechanical devices operating in a fluidic environment. PMID:22181268

Chen, Chao; Ma, Ming; Jin, Kai; Liu, Jefferson Zhe; Shen, Luming; Zheng, Quanshui; Xu, Zhiping

2011-10-18

414

Damping of transient energy growth of three-dimensional perturbations in hydromagnetic pipe flow  

NASA Astrophysics Data System (ADS)

The stability of infinitesimal three-dimensional perturbations in hydromagnetic pipe flow where the applied magnetic field is in the streamwise direction is considered. The study is limited to the case of small magnetic Reynolds numbers and the main objective of the paper is to study the transient evolution of the kinetic energy. A general effect of the magnetic field is to increase the damping of the eigenvalues of the individual perturbation modes. For the case of infinitely long perturbations, which in the non-magnetic case has been found to have the largest transient growth, the magnetic field perturbations are decoupled from the flow and there is no effect on the stability properties of the flow. For shorter waves, and for moderate values of the interaction parameter (I = RmA2 approx 1-3) the hydromagnetic damping effect on the transient energy growth is, however, substantial, especially for small azimuthal mode numbers n. (Here Rm is the magnetic Reynolds number and A is the Alfvén number.) This parameter range has been found in experiments to give significantly higher transitional Reynolds numbers (Fraim and Heiser, 1968). Since the hydromagnetic damping effect is weak for long waves and large for shorter waves, the implications of the results to ordinary pipe flow is that the energy growth found for short waves may be more crucial as a mechanism for transition than the corresponding growth for longer waves.

Åkerstedt, Hans O.

1995-05-01

415

Energy injection in closed turbulent flows: Stirring through boundary layers versus inertial stirring  

NASA Astrophysics Data System (ADS)

The mean rates of energy injection and energy dissipation in steady regimes of turbulence are measured in two types of flow confined in closed cells. The first flow is generated by counterrotating stirrers and the second is a Couette-Taylor flow. In these two experiments the solid surfaces that set the fluid into motion are at first smooth, so that everywhere the velocity of the stirrers is locally parallel to its surface. In all such cases the mean rate of energy dissipation does not satisfy the scaling expected from Kolmogorov theory. When blades perpendicular to the motion are added to the stirring surfaces the Kolmogorov scaling is observed in all the large range of Reynolds numbers (103flow. With smooth stirrers the dissipation in the bulk is weaker than the Reynolds-number-dependent dissipation in the boundary layers. With rough (or inertial) stirrers the dissipation in the bulk dominates, hence the Kolmogorovian global behavior.

Cadot, O.; Couder, Y.; Daerr, A.; Douady, S.; Tsinober, A.

1997-07-01

416

Optimal frequency for flow energy harvesting using flapping foils and its relation with wake instability  

NASA Astrophysics Data System (ADS)

Inspired by the correlation between the propulsion efficiency of a flapping foil propeller and stability of the wake behind it (which leads to the optimal Strouhal number for propulsion), we numerically simulated a foil in energy harvesting mode, and investigated the relation between wake stability and the energy harvesting efficiency (defined as the portion of incoming flow energy extracted by the system). The base flow is computed using a Navier-Stokes algorithm and the flow stability analysis is performed numerically via the Orr-Sommerfield equation. The wake is found to be convectively unstable and the frequency of the most (spatially) unstable mode fw is determined. The optimal efficiency occurs when fw is close to f (the oscillation frequency of the foil), which is achieved when f is close to 0.15 (hereby f is normalized by the chord length and the speed of incoming flow). In addition, for this "foil-wake resonance" to happen there must be significant leading edge separation associated with large effective angles of attack.

Zhu, Qiang

2010-11-01

417

Determination of transient disturbance energy flow in electric power systems via cross time-frequency distribution  

NASA Astrophysics Data System (ADS)

In electric power systems, the flow of electric power is an important issue for the control and management of the system. However, under transient-states caused by electrical disturbances, it is not a simple task to determine the flow of transient disturbance energy in an analytic way with high accuracy. The proposed algorithm for the determination of transient disturbance energy flow is based on cross time-frequency analysis that provides time- and frequency- localized phase difference information. Hence, based on the cross time-frequency distribution of the transient voltage and current, the classical parameters in power systems are modified for transient analysis. The transient power factor angle will determine the direction of transient disturbance energy (real and reactive) flows in power distribution system networks. For the verification of the proposed algorithm, a practical model of a power system is simulated by EMTP (Electromagnetic Transient Program). In addition, knowledge of this nature should greatly facilitate automatic identification of transient events and determination of the physical location of the source of various transient disturbances.

Shin, Yong-June; Powers, Edward J.; Grady, W. M.; Arapostathis, Ari

2004-10-01

418

Towards a new model of tumuli growth: Incorporating bending models and observations of active lava flows  

NASA Astrophysics Data System (ADS)

Tumuli are the morphologic expression of pressure concentrating within an inflating lava flow. An existing model of tumuli growth (Rossi and Gudmundsson, 1996), suggests that approximately 40m of magmastic overpressure is needed to bend the surface crust of an active lava flow into the characteristic whale-back shape of a tumulus. This model assumes a small-deflection bending of a broken, rigid crust overlying a stronger viscoelastic layer, and uses reasonable values of tumuli dimensions and crustal thickness as boundary conditions. We measured the dimensions and crustal thicknesses of more than 100 tumuli on flows at Mount Etna and Kilauea volcanoes, and used the model to generate pressure estimates for each tumuli in an attempt to discover the nature and magnitude of pressure variations with active lava flow interiors. Although the model gives reasonable values of magmastic pressure for many of our measured tumuli, some values were unreasonably high (greater than 10m magmastic pressure) or low (less than 0.1m magmastic pressure). For those tumuli that have unreasonably low pressure estimates with the existing model, we find that more reasonable values are calculated if we consider whether the edges of the tumuli are clamped. Clamping requires greater magmastic overpressure to bend and break the edges than predicted by the current model. We also find that shape affects the pressure estimates. Tumuli are typically elliptical in plan view, and require greater pressure for bending than for circular features. For those tumuli that yield unreasonably large values of magmastic overpressure, a large-deflection bending model yields more reasonable values. Also, allowing the brittle crust to contribute to the strength of the bending layer improves the calculated values. We also incorporate observations of actively growing tumuli, and find that some are as wide as the entire flow lobe. Many also form at near constrictions in the flow lobe. Cracking of the flow surface may occur very early in the growth of tumuli, and thus their final height reflects mostly lifting, rather than bending. In these cases, bending is only considered during the initial stages of crack formation, with lifting the dominant process responsible for tumulus height.

Anderson, S. W.; Smrekar, S. E.; Stofan, E. R.; Sengstacken, A.

2006-12-01

419

PREPARATION OF ACTIVATED CARBON FROM COCONUT SHELL IN A SMALL SCALE COCURRENT FLOW ROTARY KILN  

Microsoft Academic Search

Activated carbons were prepared at 800°C in a small scale rotary kiln fed either with fresh or precarbonized coconut shell, employing a mixture of steam and air, flowing cocurrently. Typical product rates obtained were 0.2 and 0.6g\\/min for fresh and precarbonized shell respectively. Product surface area increased with increasing water input concentration from about 0.5 to 5 g H2O\\/g feed, resulting

JORGE LAINE; SANTIAGO SIMONI; RICARDO CALLES

1991-01-01

420

Active ultrasonic cross-correlation flowmeters for mixed-phase pipe flows  

Microsoft Academic Search

This paper describes two ultrasonic flowmeters that employ the active cross-correlation technique and use a simple clamp-on transducer arrangement. The flowmeter for solid\\/liquid flows was tested over a wide range of coal concentrations in water and oil. The measured velocity based on the peak position of the cross-correlation function is consistently higher by about 15% than the average velocity measured

S. H. Sheen; A. C. Raptis

1985-01-01

421

Active ultrasonic cross-correlation flowmeters for mixed-phase pipe flows  

Microsoft Academic Search

Two ultrasonic flowmeters which employ the active cross-correlation technique and use a simple clamp-on transducer arrangement are discussed. The flowmeter for solid\\/liquid flows was tested over a wide range of coal concentration in water and oil. The measured velocity based on the peak position of the cross-correlation function is consistently higher by about 15% than the average velocity measured by

S. H. Sheen; A. C. Raptis

1984-01-01

422

Active Flow Control over a NACA 0015 Airfoil using a ZNMF Jet  

Microsoft Academic Search

The effect of using a wall-normal, zero-net-mass-flux (ZNMF) jet located at the leading edge of a NACA 0015 airfoil as an active flow control device was investigated. Experiments were conducted over a two-dimensional airfoil in a water tunnel at a Reynolds number of 3.08 x 104 for parametric investigations and particle image velocimetry (PIV) and at a Reynolds number of

A. Tuck; J. Soria

423

Active Flow Control on Low-Aspect Ratio, Low-Reynolds Number Airfoils  

Microsoft Academic Search

Insect flight observations show high-lift mechanisms that rely on leading-edge vortex stabilization. These processes are intimately coupled to the flapping motion of the insect wing. In fixed wing applications, suitable for micro-air vehicles, active flow control may be capable of providing similar influence over vortex formation and stabilization. Steady and pulsed mass injection strategies are used to explore the open-loop

Matthew Munson; Daegyoum Kim; William Dickson; Morteza Gharib

2008-01-01

424

Rapid parallel flow cytometry assays of active GTPases using effector beads.  

PubMed

We describe a rapid assay for measuring the cellular activity of small guanine triphosphatases (GTPases) in response to a specific stimulus. Effector-functionalized beads are used to quantify in parallel multiple GTP-bound GTPases in the same cell lysate by flow cytometry. In a biologically relevant example, five different Ras family GTPases are shown for the first time to be involved in a concerted signaling cascade downstream of receptor ligation by Sin Nombre hantavirus. PMID:23928044

Buranda, Tione; Basuray, Soumik; Swanson, Scarlett; Agola, Jacob; Bondu, Virginie; Wandinger-Ness, Angela

2013-08-06

425

Exhausting handgrip exercise reduces the blood flow in the active calf muscle exercising at low intensity  

Microsoft Academic Search

The calf and forearm blood flows (Q\\u000acalf and Q\\u000aforearm respectively), blood pressure, heart rate and oxygen uptake of six men and women were studied during combined leg and handgrip exercise to determine whether a reduction of exercise-induced hyperaemia would occur in the active leg when exhausting rhythmic handgrip exercise at 50% maximal voluntary contraction (MVC) was superimposed upon

Atsuko Kagaya; Mitsuru Saito; Futoshi Ogita; Minoru Shinohara

1994-01-01

426

The effect of amphetamine on regional cerebral blood flow during cognitive activation in schizophrenia  

Microsoft Academic Search

To explore the role of monoamines on cerebral function during specific prefrontal cognitive activation, we conducted a double-blind placebo-controlled crossover study of the effects of 0.25 mg\\/kg oral dextroamphetamine on regional cerebral blood flow (rCBF) as determined by 133Xe dynamic single-photon emission-computed tomography (SPECT) during performance of the Wisconsin Card Sorting Test (WCST) and a sensorimotor control task. Ten patients

David G. Daniel; Daniel R. Weinberger; Douglas W. Jones; Jeffrey Fl Zigun; Richard Coppola; Sharon Handel; Llewellyn B. Bigelow; Terry E. Goldberg; Karen F. Berman; Joel E. Kleinman

1991-01-01

427

Pahoehoe Flow  

USGS Multimedia Gallery

A small active p?hoehoe flow overplating an older 'a'? flow on the upper TEB flow field. There were a few small scattered breakouts above the pali, but the majority of the surface activity was flowing through Royal Gardens and onto the coastal plain....

2010-06-18

428

Fluid Flow Stimulates Tissue Plasminogen Activator Secretion by Cultured Human Endothelial Cells  

NASA Astrophysics Data System (ADS)

Wall shear stress generated by blood flow may regulate the expression of fibrinolytic proteins by endothelial cells. Tissue plasminogen activator (tPA) and plasminogen activator inhibitor, type 1 (PAI-1) secretion by cultured human endothelial cells were not affected by exposure to venous shear stress (4 dynes/cm2). However, at arterial shear stresses of 15 and 25 dynes/cm2, the tPA secretion rate was 2.1 and 3.0 times greater, respectively, than the basal tPA secretion rate. PAI-1 secretion was unaffected by shear stress over the entire physiological range.

Diamond, S. L.; Eskin, S. G.; McIntire, L. V.

1989-03-01

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

Nonlinear effects of pulsed periodic energy supply on shock wave structure of transonic flow around airfoils  

NASA Astrophysics Data System (ADS)

The work deals with an investigation of possibilities of controlling the aerodynamic characteristics of airfoils with the aid of external local pulsed-periodic energy supply at transonic flight regimes. The alteration of flow structure near a symmetric airfoil and its wave drag has been studied on the basis of a numerical solution of two-dimensional nonstationary gas dynamics equations versus the energy supply period, the localization and shape of the energy supply zone. The energy supply upstream of the closing shock in the immediate proximity of the contour in the zones extended along it is found to result in a considerable reduction of the profile wave drag. The nature of such a drag reduction is elucidated. The existence of a limiting frequency of energy supply is established.

Aulchenko, S. M.; Zamuraev, V. P.; Kalinina, A. P.

2006-06-01

431

Watching photoinduced chemistry and molecular energy flow in solution in real time.  

PubMed

Energized molecules are the essential actors in chemical transformations in solution. As the rearrangement of bonds requires a movement of nuclei, vibrational energy is often the driving force for a reaction. Vibrational energy can be redistributed within the "hot" molecule, or relaxation can occur when molecules interact. Both processes govern the rates, pathways, and quantum yields of chemical transformations in solution. Unfortunately, energy transfer and the breaking, formation, and rearrangement of bonds take place on ultrafast timescales. This Review highlights experimental approaches for the direct, ultrafast measurement of photoinduced femtochemistry and energy flow in solution. In the first part of this Review, we summarize recent experiments on intra- and intermolecular energy transfer. The second part discusses photoinduced decomposition of large organic peroxides, which are used as initiators in free radical polymerization. The mechanisms and timescales of their decarboxylation determine the initial steps of polymerization and the microstructure of the polymer product. PMID:12772152

Assmann, Jens; Kling, Matthias; Abel, Bernd

2003-05-25

432

Energy Storage of Linear and Cyclic Electron Flows in Photosynthesis 1  

PubMed Central

The energy storage of photosynthesis in the green alga Chlorella vulgaris was determined by pulsed, time-resolved photoacoustics. The energy storage of the linear electron transfer process in photosynthesis, of cyclic photosystem (PS) I, and possibly of PSII was determined by selection of excitation wavelength and of flash interval. At 695 nm excitation, a rather large cyclic PSI energy storage of 0.68 ± 0.04 eV/quantum of energy at 8 ms after a 1-?s flash was obtained. This energy remained the same at flash intervals of 0.35 to 60 s and was independent of the presence of 3-(3,4-dichlorophenyl)-1,1-dimethylurea. We tentatively assign this energy to the ferredoxin-NADP-reductase-ferredoxin and oxidized cytochrome b6/f complexes. An efficient distribution of energy between cyclic and linear systems is obtained with the simple assumption that the turnover time of the cyclic system is slower than that of the linear system. The energy storage of linear electron flow was determined by 655 nm excitation of Chlorella with a short flash interval of 0.35 s per flash. It was calculated to be 0.50 ± 0.03 eV/hv, close to that expected for oxygen and NADPH formation. The energy storage of PSII is determined by excitation of Chlorella at 655 nm with a long flash interval of 60 s per flash. It was calculated to be 1.07 ± 0.05 eV/hv, consistent with the energy storage being in S-states and the secondary electron acceptor of PSII with a calculated redox energy of 1.03 eV/hv. In the presence of 1 ?m 3-(3,4-dichlorophenyl)-1,1-dimethylurea, the calculated energy storage in PSII is still significant, 0.53 ± 0.04 eV/hv. This probably indicates a significant cyclic electron flow around PSII. These cyclic flows may contribute considerably to energy storage in photosynthesis.

Cha, Yuan; Mauzerall, David C.

1992-01-01

433

Active energy harvesting from microbial fuel cells at the maximum power point without using resistors.  

PubMed

Microbial fuel cell (MFC) technology offers a sustainable approach to harvest electricity from biodegradable materials. Energy production from MFCs has been demonstrated using external resistors or charge pumps, but such methods can only dissipate energy through heat or receive electrons passively from the MFC without any controllability. This study developed a new approach and system that can actively extract energy from MFC reactors at any operating point without using any resistors, especially at the peak power point to maximize energy production. Results show that power harvesting from a recirculating-flow MFC can be well maintained by the maximum power point circuit (MPPC) at its peak power point, while a charge pump was not able to change operating point due to current limitation. Within 18-h test, the energy gained from the MPPC was 76.8 J, 76 times higher than the charge pump (1.0 J) that was commonly used in MFC studies. Both conditions resulted in similar organic removal, but the Coulombic efficiency obtained from the MPPC was 21 times higher than that of the charge pump. Different numbers of capacitors could be used in the MPPC for various energy storage requirements and power supply, and the energy conversion efficiency of the MPPC was further characterized to identify key factors for system improvement. This active energy harvesting approach provides a new perspective for energy harvesting that can maximize MFC energy generation and system controllability. PMID:22486712

Wang, Heming; Park, Jae-Do; Ren, Zhiyong

2012-04-17

434

Flow injection catalase activity measurement based on gold nanoparticles/carbon nanotubes modified glassy carbon electrode.  

PubMed

Amperometric flow injection method of hydrogen peroxide analysis was developed based on catalase enzyme (CAT) immobilization on a glassy carbon electrode (GC) modified with electrochemically deposited gold nanoparticles on a multiwalled carbon nanotubes/chitosan film. The resulting biosensor was applied to detect hydrogen peroxide with a linear response range 1.0×10(-7)-2.5×10(-3)M with a correlation coefficient 0.998 and response time less than 10s. The optimum conditions of film deposition such as potential applied, deposition time and pH were tested and the flow injection conditions were optimized to be: flow rate of 3ml/min, sample volume 75?l and saline phosphate buffer of pH 6.89. Catalase enzyme activity was successfully determined in liver homogenate samples of rats, raised under controlled dietary plan, using a flow injection analysis system involving the developed biosensor simultaneously with spectrophotometric detection, which is the common method of enzymatic assay. PMID:22817944

El Nashar, Rasha Mohamed

2011-12-09

435

Use of flow cytometry to monitor cell damage and predict fermentation activity of dried yeasts.  

PubMed

Viable dried yeast is used as an inoculum for many fermentations in the baking and wine industries. The fermentative activity of yeast in bread dough or grape must is a critical parameter of process efficiency. Here, it is shown that fluorescent stains and flow cytometry can be used in concert to predict the abilities of populations of dried bakers' and wine yeasts to ferment after rehydration. Fluorescent dyes that stain cells only if they have damaged membrane potential (oxonol) or have increased membrane permeability (propidium iodide) were used to analyse, by flow cytometry, populations of rehydrated yeasts. A strong relationship (r2 = 0.99) was found between the percentages of populations staining with the oxonol and the degree of cell membrane damage as measured by the more traditional method of leakage of intracellular compounds. There were also were good negative relationships (r2 > or = 0.83) between fermentation by rehydrated bakers' or wine dry yeasts and percentage of populations staining with either oxonol or propidium iodide. Fluorescent staining with flow cytometry confirmed that factors such as vigour of dried yeast mixing in water, soaking before stirring, rehydration in water or fermentation medium and temperature of rehydration have profound effects on subsequent yeast vitality. These experiments indicate the potential of flow cytometry as a rapid means of predicting the fermentation performance of dried bakers' and wine yeasts. PMID:10971752

Attfield, P V; Kletsas, S; Veal, D A; van Rooijen, R; Bell, P J

2000-08-01

436

Operational Control of the Activated Sludge Process. Return Sludge Flow Control.  

National Technical Information Service (NTIS)

The return sludge flow, or more precisely, the clarifier sludge flow which includes both return sludge and excess waste sludge flows, should be adjusted to meet measurable process requirements. Attempts to maintain arbitrary return sludge flow percentages...

A. W. West

1973-01-01

437

Hydroelastic response and energy harvesting potential of flexible piezoelectric beams in viscous flow  

NASA Astrophysics Data System (ADS)

Electroactive polymers such as piezoelectric elements are able to generate electric potential differences from induced mechanical deformations. They can be used to build devices to harvest ambient energy from natural flow-induced deformations, e.g., as flapping flags subject to flowing wind or artificial seaweed subject to waves or underwater currents. The objectives of this study are to (1) investigate the transient hydroelastic response and energy harvesting potential of flexible piezoelectric beams fluttering in incompressible, viscous flow, and (2) identify critical non-dimensional parameters that govern the response of piezoelectric beams fluttering in viscous flow. The fluid-structure interaction response is simulated using an immersed boundary approach coupled with a finite volume solver for incompressible, viscous flow. The effects of large beam deformation, membrane tension, and coupled electromechanical responses are all considered. Validation studies are shown for the motion of a flexible filament in uniform flow, and for a piezoelectric beam subject to base vibration. The predicted flutter velocities and frequencies also compared well with published experimental and numerical data over a range of Reynolds numbers for varying fluid and solid combinations. The results showed that for a heavy beam in a light fluid (i.e., high ?? regime), flutter incepts at a lower critical speed with a lower reduced frequency than for a light beam in a heavy fluid (i.e., low ?? regime). In the high ?? regime, flutter develops at the second mode and is only realized when the fluid inertial forces are in balance with the solid elastic restoring forces, which leads to large amplitude oscillations and complex wake patterns; the flutter speed is practically independent of the Reynolds number (Re) and solid to fluid mass ratio (??), because the response is dominated by the solid inertial forces. In the low ?? regime, fluid inertial forces dominate, flutter develops at higher modes and is only realized when the solid inertial forces are proportioned to the solid elastic restoring forces; the flutter speed depends on both Re and ??, and viscous force and beam tension effects tend to delay flutter and reduce vibration amplitudes, leading to thinner, more simplified wake patterns. The results demonstrate that energy extraction via fluttering piezoelectric beams is possible. The overall efficiency was observed to be influenced by the piezoelectric circuit resistance, which is known to be directly related to the square of the piezoelectric coupling factor. The results show that the maximum strain limit of piezoelectrics may be exceeded, and hence careful optimization of the material and geometry is recommended to maximize the energy capture for a given range of expected flow conditions while satisfying safety and reliability requirements.

Akcabay, Deniz Tolga; Young, Yin Lu

2012-05-01

438

Evidence for active cyclic electron flow in twig chlorenchyma in the presence of an extremely deficient linear electron transport activity.  

PubMed

Fast and slow chlorophyll fluorescence induction curves at high and low actinic visible light, post-illumination changes in fluorescence yield and reflectance changes at 820 nm induced by far-red light were used to characterize the state of PSII and PSI and their electron transport capabilities in chlorophyllous twig cortices of Eleagnus angustifolius L., while corresponding leaves served as controls. Twigs displayed low dark-adapted PSII photochemical efficiencies and particularly low linear electron transport rates when illuminated. In addition, their PSII population was characterized by a high proportion of inactive, non-Q(B)-reducing centers and an incomplete quenching of fluorescence during the slow induction phase. It is suggested that PSII in twigs is an inefficient electron donor to PSI and/or the reductive pentose phosphate cycle. Yet, in spite of this apparent PSII deficiency, pools of intermediate electron carriers and potential PSI activity were more than sufficient to support the observed linear electron transport rates. Moreover, the rate of PSI reduction upon far-red/dark transitions and the magnitude of fluorescence yield increase upon white light/dark transitions were compatible with an efficient electron flow to PSI from stromal donors in the absence of PSII activity. We conclude that corticular chlorenchyma may be actively engaged in cyclic at the expense of a linear electron flow and discuss the possible physiological significance of this finding in conjunction with the particular microenvironmental conditions encountered within twigs. PMID:16773373

Kotakis, Ch; Petropoulou, Y; Stamatakis, K; Yiotis, Ch; Manetas, Y

2006-06-14

439