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1

Characterization of activation energy for flow in metallic glasses  

SciTech Connect

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

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

2011-01-15

2

Active Flows  

USGS Multimedia Gallery

The terminus of the active flows from Kilauea's east rift zone, the lighter color lava seen here, have reached down to about the 1100-ft elevation just east of the older TEB flow field. If these flows continue to push forward, they will likely end up back on top of the older TEB flow field at the ba...

2010-06-18

3

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

ERIC Educational Resources Information Center

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

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

1984-01-01

4

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

PubMed

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 neuroglial units that leads to an overall increase in energy utilization in this population. On the basis of this definition, the key aspects of modern biochemical and biophysical approaches to neuroenergetics are considered from the perspective of the links between these approaches within the context of the free energy minimization principle and the neurophysiological conception of deviance detection. In this light, we consider brain basal activity as subserving internal representations of the environment (predictive coding), and brain activation as reflecting the level of deviance from predictive coding. PMID:20092923

Strelnikov, Kuzma

2010-04-01

5

Energy Flow  

NSDL National Science Digital Library

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

2003-12-26

6

The role of high energy photons and particles in accretion flows in active nuclei  

NASA Technical Reports Server (NTRS)

The creation of high energy pairs and photons in the conversion of gravitational to thermal energy is a process common to most accretion models for active galactic nuclei. These are two observational methods designed to explore this process: direct observations of the hot photons, through hard X-ray and gamma-ray data, and indirect observations of the energetic pairs, through their polarized, nonthermal low frequency radiation. However, interpretation of these observations in terms of the conditions in the inner accretion flow requires understanding of the various processes which modify the pair and photon distributions within the hot, dense core. These processes include opacity effects within the pair/photon plasma, Compton losses on external photons, further acceleration of the pairs and further radiation by the pairs, and the dynamic interaction of the pair/photon plasma with the surrounding gas. Current observational and theoretical work is reviewed and new directions are considered in a search for constraints on or tests of accretion models of active nuclei.

Eilek, Jean A.

1988-01-01

7

Active Lava Flow  

USGS Multimedia Gallery

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

2010-07-29

8

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

9

NEED Project: Energy Flows  

NSDL National Science Digital Library

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

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

Activation energy for mobility of dyes and proteins in polymer solutions: from diffusion of single particles to macroscale flow.  

PubMed

We measure the activation energy Ea for the diffusion of molecular probes (dyes and proteins of radii from 0.52 to 6.9 nm) and for macroscopic flow in a model complex liquid-aqueous solutions of polyethylene glycol. We cover a broad range of polymer molecular weights, concentrations, and temperatures. Fluorescence correlation spectroscopy and rheometry experiments reveal a relationship between the excess of the activation energy in polymer solutions over the one in pure solvent ?Ea and simple parameters describing the structure of the system: probe radius, polymer hydrodynamic radius, and correlation length. ?Ea varies by more than an order of magnitude in the investigated systems (in the range of ca. 1-15 kJ/mol) and for probes significantly larger than the polymer hydrodynamic radius approaches the value measured for macroscopic flow. We develop an explicit formula describing the smooth transition of ?Ea from the diffusion of molecular probes to macroscopic flow. This formula is a reference for the quantitative analysis of specific interactions of moving nano-objects with their environment as well as active transport. For instance, the power developed by a molecular motor moving at constant velocity u is proportional to u2exp(Ea/RT). PMID:24329475

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

2013-11-27

12

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

NASA Astrophysics Data System (ADS)

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

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

2013-11-01

13

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.

14

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.

15

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

NASA Astrophysics Data System (ADS)

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

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

2012-09-01

16

Food Web and Energy Flow  

NSDL National Science Digital Library

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

Galle, Janet R.; Warren, Patricia A.

2005-01-01

17

The role of activation energy and reduced viscosity on the enhancement of water flow through carbon nanotubes  

NASA Astrophysics Data System (ADS)

Molecular dynamics simulations are carried out to study the pressure driven fluid flow of water through single walled carbon nanotubes. A method for the calculation of viscosity of the confined fluid based on the Eyring theory of reaction rates is proposed. The method involves the calculation of the activation energy directly from the molecular dynamics trajectory information. Computations are performed using this method to study the effect of surface curvature on the confined fluid viscosity. The results indicate that the viscosity varies nonlinearly with the carbon nanotube diameter. It is concluded that the reason behind the observed enhancement in the rate of fluid flow through carbon nanotubes could be the nonlinear variation of viscosity.

Babu, Jeetu S.; Sathian, Sarith P.

2011-05-01

18

Radiant Energy Flow  

NSDL National Science Digital Library

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

Consortium, The C.

2011-12-11

19

Global Energy Flows  

NSDL National Science Digital Library

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

Center, Great L.; Energy, U. S.

20

Evaluation of the activation energy of viscous flow for a binary mixture in order to estimate the thermodiffusion coefficient  

NASA Astrophysics Data System (ADS)

The evaluation of the activation energy in Eyring's viscosity theory is of great importance in estimating the thermodiffusion coefficient for associating and non-associating fluid mixtures. Several methods were used to estimate the activation energies of pure components and then extended to mixtures of linear hydrocarbon chains. Results show that the recent model of Abbasi et al. [J. Chem. Phys. 131: 014502, 2009.] gives a good outcome in determining the activation energy of the components of a binary mixture. The activation energy model for pure components is shown to be useful for obtaining the activation energy of the mixture. In this paper, the activation energy model using alternative forms of Eyring's viscosity theory is used to estimate the thermodiffusion coefficient values for hydrocarbon binary mixtures. Comparisons of predicted thermodiffusion coefficients using different theoretical models with the experimental data show good capability of the activation energy model.

Abbasi, Alireza; Saghir, M. Ziad; Kawaji, Masahiro

2011-05-01

21

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

22

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

23

Energy flow in piezoelectric energy harvesting systems  

NASA Astrophysics Data System (ADS)

In the research of piezoelectric energy harvesting (PEH), the previous foci were mostly on the amount of energy that can be harvested from the ambient vibration sources. Other portions of energy, e.g., the energy dissipated during the harvesting process, were seldom considered in PEH systems. Yet, the ignorance on these energies might cause some misunderstanding in the studies of energy harvesting. This paper sets up an energy flow based framework for the analysis of PEH systems. An energy flow chart is introduced to comprehensively illustrate the energy paths within the PEH system. Taking the interface circuits of standard energy harvesting (SEH) and synchronized switch harvesting on inductor (SSHI) as examples, different branches of energy flow in the PEH systems are quantitatively investigated. In the previous literature, only the harvested energy was emphasized as a function of the rectified voltage or its corresponding DC load resistance. To be more general, we show that both the harvesting energy and dissipated energy change with the rectified voltage; in addition, these two portions of energy also depend on the ratio between the rectifier voltage drop and the open circuit voltage. Three experiments are carried out with an SSHI device to measure its performances on energy harvesting, energy dissipation, and structural damping. The experimental results show good agreement with theoretical analysis. The functional relations among these branches of energy flow are found.

Liang, Junrui; Liao, Wei-Hsin

2011-01-01

24

Energy Flow in Interference Fields  

NASA Astrophysics Data System (ADS)

The purpose of this paper is to examine ocean acoustic field interference patterns and their associated energy flows both through numerical modeling and analysis of actual ocean acoustic data. The numerical modeling is performed using the environmental reconstruction obtained from data collected during the SWARM 95 experiment. The ocean acoustic data were collected during the 1990 NATIVE 1 experiment by a set of infrasonic (0.4 to 20 Hz) freely drifting vector sensors ("combined receivers"). The numerical modeling results indicate that, whereas under adiabatic mode propagation the interference pattern responds to introduction of water column fluctuations by simply shifting in range and frequency, effects of mode coupling result in more complicated behavior. Interference patterns can be destroyed in the presence of weak mode coupling, particularly where the dynamic range of the pattern (peak-to-trough ratio) is small. This dynamic range in the range/frequency plane is depth dependent. It also depends upon which property of the acoustic field is considered; the striation patterns in reactive intensity magnitude spectra can have much greater dynamic range, and therefore be more resistant to effects of mode coupling, than those in the acoustic pressure spectra at a given depth, and vice versa. Acoustic energy flows at 7.0 Hz measured by the acoustic vector sensing Swallow floats as a 120-m-deep source was towed out to a distance of nearly 19 km display interesting features; the active intensity predominantly is in the radial direction away from the source and represents net flux of energy down the waveguide, and the reactive intensity is mostly vertical since the field's spatial structure typically varies the greatest in that direction. However, near a pressure field minimum, the vertical net flux becomes significant and changes direction, and both components of the reactive intensity change direction. Over short time scales, even the radial component of active intensity can change direction, indicating net flux of energy towards the source. In addition, acoustic particle motion changes polarity between prograde and retrograde motion over short time periods when passing by a minimum in the pressure spectrum.

D'Spain, G. L.; Williams, D. P.; Rovner, G.; Kuperman, W. A.

2002-06-01

25

US energy flow, 1990  

SciTech Connect

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 relatively mild, nation-wide summer and winter. All end-use sectors were affected by the high fuel prices related to the Kuwait-Iraq war in the last half of the year and by an attendant economic downturn. Electrical use rose slightly and thus deviated from the 3-4% annual increases recorded in the previous decade. Nuclear energy's contribution to electrical generation increased to almost 21%, and capacity factors reached 66%, an all time high in the US. Renewable sources of energy apart from hydroelectric power showed negligible growth. Domestic natural gas and coal production rose, and oil production continued its steady decline. As oil constitutes 41% of US energy consumption, failing domestic production has been augmented by imports. Collectively energy imports constituted two-thirds of the US trade deficit in 1990. The ratio between energy consumption and GNP declined slightly in 1990 as it has for almost every year since 1972. The Services'' component of the GNP increased in 1990 and the Goods'' and Structures'' components declined in keeping with an even longer trend. 29 refs., 7 figs., 4 tabs.

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

1991-06-01

26

Boeing active flow control system  

NASA Astrophysics Data System (ADS)

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

Jacot, A. Dean; Calkins, Frederick T.

2000-06-01

27

Active Flow Control Activities at NASA Langley  

NASA Technical Reports Server (NTRS)

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

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

2004-01-01

28

Energy Flow Method for the Study of Motorcycle Wobble Mode  

Microsoft Academic Search

A concept of the energy flow is introduced in order to study the motorcycle wobble mode. The activation mechanism of the wobble oscillation is made clear in the framework of the energy flow concept It is found that the wobble mode is activated mainly by the yaw rate and roll rate motion and is suppressed by the lateral acceleration and

Tsuyoshi KATAYAMA; Tomoo NISHIMI

1990-01-01

29

Analysis of Motorcycle Weave Mode by using Energy Flow Method  

Microsoft Academic Search

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

Yoshitaka Marumo; Tsuyoshi Katayama

2009-01-01

30

Energy Flow in the Atmosphere  

NSDL National Science Digital Library

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

31

Measurement of electromagnetic energy flow  

NASA Astrophysics Data System (ADS)

The measurement of electromagnetic energy flow is an integral part of solving radiation-budget and optical-characterization problems. It is therefore very important to understand clearly what specific measurement is afforded by an optical instrument and how to model this measurement theoretically. We will not discuss technical and technological issues related to the development of sensitive and efficient detectors of light. Instead, the discussion will focus on the precise definitions of general measurement principles and their specific practical implications in the framework of electromagnetic scattering by particles and particle groups. We will discuss in succession measurements with direction-insensitive detectors, monodirectional well-collimated, and panoramic well-collimated radiometers. Special attention will be paid to the electromagnetic response of a well-collimated radiometer to polychromatic light. We will see, in particular, that although the main characteristic of electromagnetic energy flow is the Poynting vector, the actual measurement of this quantity is possible only in very special cases.

Mishchenko, M. I.

2012-12-01

32

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

33

Dissipative control of energy flow in interconnected systems  

NASA Technical Reports Server (NTRS)

Dissipative energy flow controllers are designed for interconnected modal subsystems. Active feedback controllers for vibration suppression are then viewed as either an additional subsystem or a dissipative coupling. These controllers, which are designed by the LQG positive real control approach, maximize energy flow from a specified modal subsystem.

Kishimoto, Y.; Bernstein, D. S.; Hall, S. R.

1993-01-01

34

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

Microsoft Academic Search

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

Souvik Dasgupta; Sanjib Kumar Sahoo; Sanjib Kumar Panda

2011-01-01

35

Go with the Energy Flow  

NSDL National Science Digital Library

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

Integrated Teaching And Learning Program

36

Gradient Vector Flow Fast Geometric Active Contours  

Microsoft Academic Search

Abstract—In this paper, we propose an edge-driven bidirectional geometric flow for boundary extraction. To this end, we combine the geodesic active contour flow [3] and the gradient vector flow external force for snakes,[25]. The resulting motion equation is considered within a level set formulation [19], can deal with topological changes,and important shape deformations. An efficient numerical,schema,is used for the flow

Nikos Paragios; Olivier Mellina-gottardo; Visvanathan Ramesh

2003-01-01

37

Observing and modeling Earths energy flows  

SciTech Connect

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{sup -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 B.; Schwartz S.

2012-05-11

38

Energy Flow through a Paper Ecosystem.  

ERIC Educational Resources Information Center

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

Aston, T. J.

1988-01-01

39

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

40

CFD Modeling for Active Flow Control  

NASA Technical Reports Server (NTRS)

This presentation describes current work under UEET Active Flow Control CFD Research Tool Development. The goal of this work is to develop computational tools for inlet active flow control design. This year s objectives were to perform CFD simulations of fully gridded vane vortex generators, micro-vortex genera- tors, and synthetic jets, and to compare flowfield results with wind tunnel tests of simple geometries with flow control devices. Comparisons are shown for a single micro-vortex generator on a flat plate, and for flow over an expansion ramp with sidewall effects. Vortex core location, pressure gradient and oil flow patterns are compared between experiment and computation. This work lays the groundwork for evaluating simplified modeling of arrays of devices, and provides the opportunity to test simple flow control device/sensor/ control loop interaction.

Buning, Pieter G.

2001-01-01

41

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

42

Magnetic energy flow in the solar wind.  

NASA Technical Reports Server (NTRS)

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

Modisette, J. L.

1972-01-01

43

Marker Transport Through Ecosystem Energy Flow  

Microsoft Academic Search

Markers are substances which are artificially introduced into ecosystems in small quantities and which have no acute effects on energy flow. A marker might be a pollutant which affects life significantly only over long time frames. Alternatively, a marker might be a benign substance easily detected in small amounts and introduced in order to trace energy flow and so evaluate

Clark Jeffries; Joel E. Cohen

1996-01-01

44

U.S. Energy Flow - 1999  

Microsoft Academic Search

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 10¹. One Btu is the quantity of heat needed to raise the temperature of

Kaiper

2001-01-01

45

Diagnostics of turbulent flow parmeters of active mixture in fast axial flow CO2 laser  

Microsoft Academic Search

The characteristics of turbulent flow of laser mixture in high-power industrial CO2 lasers with fast axial flow have an influence on energy parameters of laser beam. In particular the transverse size of DC discharge and discharge stability depend on coefficient of turbulent diffusion. Moreover, turbulent pulsations cause small-scale optical inhomogeneities in the active medium. By the method of intra-resonator four-wave

S. A. Buyarov; V. D. Dubrov; Michail G. Galushkin; Vladimir S. Golubev; R. V. Grishayev; Andrei A. Ionin; Andrei A. Kotkov; Vladislav Y. Panchenko; Yuri N. Zavalov

2002-01-01

46

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

47

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

48

Introduction to Alternative and Renewable Energy: Energy Flow Analytics  

NSDL National Science Digital Library

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

2013-07-25

49

Activation parameters of flow through battery separators  

NASA Technical Reports Server (NTRS)

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

Blokhra, R. L.

1983-01-01

50

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

DOE Data Explorer

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

51

Transitioning Active Flow Control to Applications  

NASA Technical Reports Server (NTRS)

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

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

1999-01-01

52

Energy flow in acoustic black holes  

SciTech Connect

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).], 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. [Department of Physics, Brandon University, Brandon, Manitoba, R7A 6A9 (Canada) and Winnipeg Institute for Theoretical Physics, Winnipeg, Manitoba (Canada); Department of Physics, University of Winnipeg, Winnipeg, Manitoba, R7A 6A9 (Canada) and Winnipeg Institute for Theoretical Physics, Winnipeg, Manitoba (Canada); Department of Mathematics, Brandon University, Brandon, Manitoba, R7A 6A9 (Canada)

2006-05-15

53

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

54

Supersonic flow with feeding of energy  

NASA Technical Reports Server (NTRS)

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

Zaremba, W.

1985-01-01

55

[Energy flow in arctic aquatic ecosystems  

Microsoft Academic Search

This study is aimed at determining the major pathways of energy flow in freshwater ecosystems of the Alaskan arctic coastal plain. Selected sites for study of the processes supplying energy to streams and lakes to verify the generality of past findings will be surveyed for collection of organisms including the Colville River drainage and the lake region around Teshekpuk Lake.

Schell

1985-01-01

56

Energy flow in arctic aquatic ecosystems.  

National Technical Information Service (NTIS)

This study is aimed at determining the major pathways of energy flow in freshwater ecosystems of the Alaskan arctic coastal plain. Selected sites for study of the processes supplying energy to streams and lakes to verify the generality of past findings wi...

D. M. Schell

1985-01-01

57

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

58

Calculated viscosity-distance dependence for some actively flowing lavas  

NASA Technical Reports Server (NTRS)

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

Pieri, David

1987-01-01

59

Energy flows, metabolism and translation  

PubMed Central

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

Pascal, Robert; Boiteau, Laurent

2011-01-01

60

Energy flows, metabolism and translation.  

PubMed

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

Pascal, Robert; Boiteau, Laurent

2011-10-27

61

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

62

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

63

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

64

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

65

Changing Conceptions of Activation Energy.  

ERIC Educational Resources Information Center

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

Pacey, Philip D.

1981-01-01

66

Dynamical Bottlenecks to Intramolecular Energy Flow  

Microsoft Academic Search

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.

R. Paskauskas; C. Chandre; T. Uzer

2008-01-01

67

Dynamical Bottlenecks to Intramolecular Energy Flow  

NASA Astrophysics Data System (ADS)

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.

Paškauskas, R.; Chandre, C.; Uzer, T.

2008-02-01

68

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

2008-02-29

69

Energy flow in an arctic aquatic ecosystem.  

National Technical Information Service (NTIS)

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 ...

D. M. Schell

1993-01-01

70

Energy flow in an arctic aquatic ecosystem.  

National Technical Information Service (NTIS)

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 u...

D. M. Schell

1988-01-01

71

Energy flow in an arctic aquatic ecosystem  

Microsoft Academic Search

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

Schell

1988-01-01

72

Energy Flow in a Woodland Ecosystem.  

ERIC Educational Resources Information Center

The study of energy flow in a woodland ecosystem was attempted during a seven-day field course, using simple equipment. It is possible to quantify or estimate many of the components, and the methods used are described. Suggestions are made for maximizing education return from the available time and labor. (Author/BB)

Aston, T. J.

1978-01-01

73

Energy flow in an arctic aquatic ecosystem  

Microsoft Academic Search

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

Schell

1993-01-01

74

Energy flow in a woodland ecosystem  

Microsoft Academic Search

The study of energy flow in a woodland ecosystem was attempted during a seven-day field course, using simple equipment. It is possible to quantify or estimate many of the components, and the methods used are described. Suggestions are made for maximizing educational return from the available time and labour.

T. J. Aston

1978-01-01

75

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

76

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.

77

How does Energy Flow in Living Systems?  

NSDL National Science Digital Library

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

78

Flow energy piezoelectric bimorph nozzle harvester  

NASA Astrophysics Data System (ADS)

There is a need for a long-life power generation scheme that could be used downhole in an oil well to produce 1 Watt average power. There are a variety of existing or proposed energy harvesting schemes that could be used in this environment but each of these has its own limitations. The vibrating piezoelectric structure is in principle capable of operating for very long lifetimes (decades) thereby possibly overcoming a principle limitation of existing technology based on rotating turbo-machinery. In order to determine the feasibility of using piezoelectrics to produce suitable flow energy harvesting, we surveyed experimentally a variety of nozzle configurations that could be used to excite a vibrating piezoelectric structure in such a way as to enable conversion of flow energy into useful amounts of electrical power. These included reed structures, spring mass-structures, drag and lift bluff bodies and a variety of nozzles with varying flow profiles. Although not an exhaustive survey we identified a spline nozzle/piezoelectric bimorph system that experimentally produced up to 3.4 mW per bimorph. This paper will discuss these results and present our initial analyses of the device using dimensional analysis and constitutive electromechanical modeling. The analysis suggests that an order-of-magnitude improvement in power generation from the current design is possible.

Sherrit, Stewart; Lee, Hyeong Jae; Walkemeyer, Phillip; Hasenoehrl, Jennifer; Hall, Jeffrey L.; Colonius, Tim; Tosi, Luis Phillipe; Arrazola, Alvaro; Kim, Namhyo; Sun, Kai; Corbett, Gary

2014-04-01

79

Material and energy flows in corporate environmental management  

Microsoft Academic Search

Material and energy flows within and between the societal systems and the natural ecosystem result in the depletion of natural resources and threaten the capacity of nature to assimilate wastes and emissions. In this paper, the aim is to compare the material and energy flows of nature to these same flows in an industrial system. The ecosystem material and energy

Jouni Korhonen

2001-01-01

80

Energy efficient continuous flow ash lockhopper  

NASA Technical Reports Server (NTRS)

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

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

1989-01-01

81

Energy flow and energy dissipation in a free surface.  

NASA Astrophysics Data System (ADS)

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

Goldburg, Walter; Cressman, John

2005-11-01

82

U.S. Energy Flow -- 1995  

Microsoft Academic Search

Energy consumption in 1995 increased slightly for the fifth year in a row (from 89 to 91 quadrillion [1015<\\/sup>Btu). U.S. economic activity slowed from the fast-paced recovery of 1994, even with the continued low unemployment rates and low inflation rates. The annual increase in U.S. real GDP dropped to 4.6% from 1994�s increase of 5.8%. Energy consumption in all major

H. Miller; N. Mui; A. Pasternak

1997-01-01

83

Energy flows in complex ecological systems: a review  

Microsoft Academic Search

Energy flow drives the complex systems to evolve. The allometric scaling as the universal energy flow pattern has been found\\u000a in different scales of ecological systems. It reflects the general power law relationship between flow and store. The underlying\\u000a mechanisms of energy flow patterns are explained as the branching transportation networks which can be regarded as the result\\u000a of systematic

Jiang Zhang

2009-01-01

84

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

85

Retrofitting for DME process by energy-flow framework diagram  

Microsoft Academic Search

This paper introduces a graphic tool for thermodynamic analysis to be used in energy analysis and integration of systems. The proposed tool, known as the energy-flow framework diagram (EFD), provides a new representation of an energy-flow scheme by nodes and node partners between utility buses and energy loss buses, based on the second law analysis, the exergy concept and dividing

Danxing Zheng; Wen Cao

2007-01-01

86

[Energy flow in arctic aquatic ecosystems  

SciTech Connect

This study is aimed at determining the major pathways of energy flow in freshwater ecosystems of the Alaskan arctic coastal plain. Selected sites for study of the processes supplying energy to streams and lakes to verify the generality of past findings will be surveyed for collection of organisms including the Colville River drainage and the lake region around Teshekpuk Lake. Specific objectives are to collect food web apex organisms (fish and birds) from a variety of sites in the coastal plain to verify descriptive models of ecosystem structure and food web pathways and to compare the utilization rates by insect larvae of fresh litter and in situ primary production relative to more refractory peaty materials through seasonal sampling for isotopic analysis.

Schell, D.M.

1985-01-01

87

[Energy flow in arctic aquatic ecosystems  

SciTech Connect

This study is aimed at determining the major pathways of energy flow in freshwater ecosystems of the Alaskan arctic coastal plain. Selected sites for study of the processes supplying energy to streams and lakes to verify the generality of past findings will be surveyed for collection of organisms including the Colville River drainage and the lake region around Teshekpuk Lake. Specific objectives are to collect food web apex organisms (fish and birds) from a variety of sites in the coastal plain to verify descriptive models of ecosystem structure and food web pathways and to compare the utilization rates by insect larvae of fresh litter and in situ primary production relative to more refractory peaty materials through seasonal sampling for isotopic analysis.

Schell, D.M.

1985-12-31

88

Sensor Development for Active Flow Control  

NASA Technical Reports Server (NTRS)

Presented are the developmental efforts for MEMS sensors for a closed-loop active flow control in a low-speed wind tunnel evaluation. The MEMS sensors are designed in-house and fabricated out of house, and the shear sensors are a thermal type that are collocated with temperature and pressure sensors on a flexible polyimide sheet, which conforms to surfaces of a simple curvature. A total of 6 sensors are located within a 1.5 by 3 mm area as a cluster with each sensor being 300 pm square. The thickness of this sensor cluster is 75 pm. Outputs from the shear sensors have been compared with respect to those of the Preston tube for evaluation of the sensors on a flat plate. Pressure sensors are the absolute type and have recorded pressure measurements within 0.05 percent of the tunnel ESP pressure sensor readings. The sensors and signal conditioning electronics have been tested on both a flat plate and a ramp in Langley s 15-Inch Low-Turbulence Tunnel. The system configuration and control PC is configured with LabView, where calibration constants are stored for desired compensation and correction. The preliminary test results are presented within.

Kahng, Seun K.; Gorton, Susan A.; Mau, Johnney C.; Soto, Hector L.; Hernandez, Corey D.

2001-01-01

89

Dark Energy Domination In The Virgocentric Flow  

NASA Astrophysics Data System (ADS)

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

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

2011-04-01

90

Activities for Teaching Solar Energy.  

ERIC Educational Resources Information Center

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

Mason, Jack Lee; Cantrell, Joseph S.

1980-01-01

91

Energy flow measurements in acoustic waves in a duct.  

PubMed

Where, how much and how efficiently the energy conversion takes place in a regenerator of a thermoacoustic engine are expressed using the axial distribution of acoustic work flow and heat flow. As a first step in determining the energy flows inside the regenerator, measuring methods of the work flow are briefly described and the experimental results in an acoustic resonator are shown. Applicability of these methods to the regenerator is discussed. PMID:16987538

Biwa, Tetsushi

2006-12-22

92

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

93

An Energy-Flow Based Methodology - Application to hybrid vehicles  

Microsoft Academic Search

A new methodology is presented, based on energy-flow analysis on systems. The aim is to obtain a representation of energy flows between the various sources of a complex system, via energy storage devices connected together with electrical and mechanical converters. Coupling elements can be added to allow the connection of various subsystems. From such a representation, inversion rules lead to

P. Barrade; A. Rufer; A. Bouscayrol; LEI ELD

94

U.S. energy flow, 1992  

SciTech Connect

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

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

1993-10-01

95

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

96

Neutron activation system using water flow for ITER  

NASA Astrophysics Data System (ADS)

A neutron activation system with flowing water using the 16O(n,p)16N reaction has been designed for the International Thermonuclear Experimental Reaction (ITER) neutron yield monitor with temporal resolution, based on the experimental results carried out at the fusion neutronics source (FNS) facility of the Japan Atomic Energy Research Institute. On ITER, irradiation ends will be installed in the filler shielding module between the blanket modules at the equatorial ports. The gamma-ray counting stations will be installed on the upstairs of the pit outside the biological shield. BGO (Bi4Ge3O12) scintillation detectors will be employed to measure 6.13 MeV gamma rays emitted from 16N. The distance between the irradiation end and the counting station is ~20 m. The performance of the neutron activation system has been evaluated by using the neutron Monte Carlo code MCNP-4b with the JENDL 3.2 library. The reaction rate of 16O(n,p)16N was calculated not only at the irradiation end but also along the transfer line, which showed that the temporal resolution would be less than the ITER requirement of 100 ms including turbulent diffusion effects for the flow velocity of 10 m/s. With a flow velocity of 10 m/s, this system can measure the fusion power from 50 kW to 1 GW of the ITER operation by using two gamma-ray detectors; one detector faces the water pipe directly, and another has a collimator for higher-neutron yield. Also the calculation shows that the reaction rate is relatively insensitive to the change of the plasma position.

Nishitani, T.; Ebisawa, K.; Kasai, S.; Walker, C.

2003-03-01

97

Solar Activity and Energy  

NSDL National Science Digital Library

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

98

Integrated and spectral energy flows of the GLAS GCM  

NASA Technical Reports Server (NTRS)

Methods to analyze the generation, transport, and dissipation of energy to study geophysical fluid flows are discussed. Energetics analyses are pursued in several directions: (1) the longitudinal and time dependence on the energy flow to the stratosphere was examined as a function of geographical sector; (2) strong and weak energy flows were correlated by medium range forecasts; (3) the one dimensional spectral results (Fourier services around latitude circles) were extended to spherical harmonics over a global domain; (4) the validity of vertical velocities derived from mass convergence was examined for their effect on the conversion of eddy available potential energy to eddy kinetic energy.

Tennebaum, J.

1981-01-01

99

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

100

Characterization of Pulsed Vortex Generator Jets for Active Flow Control.  

National Technical Information Service (NTIS)

The flowfields produced by several active and passive flow control devices are being investigated experimentally and numerically as part of co- operative effort between the US Air Force Research Laboratory and the UK's Defense Evaluation & Research Agency...

C. P. Tillman, K. J. Langan, J. G. Betterton, M. J. Wilson

2003-01-01

101

U.S. Energy Flow -- 1995  

SciTech Connect

Energy consumption in 1995 increased slightly for the fifth year in a row (from 89 to 91 quadrillion [1015Btu). U.S. economic activity slowed from the fast-paced recovery of 1994, even with the continued low unemployment rates and low inflation rates. The annual increase in U.S. real GDP dropped to 4.6% from 1994?s increase of 5.8%. Energy consumption in all major end-use sectors surpassed the record-breaking highs achieved in 1994, with the largest gains (2.5%) occurring in the residential/commercial sector. Crude oil imports decreased for the first time this decade. There was also a decline in domestic oil production. Venezuela replaced Saudi Arabia as the principal supplier of imported oil. Imports of natural gas, mainly from Canada, continued to increase. The demand for natural gas reached a level not seen since the peak levels of the early 1970s and the demand was met by a slight increase in both natural gas production and imports. Electric utilities had the largest percentage increase of n.atural gas consumption, a climb of 7% above 1994 levels. Although coal production decreased, coal exports continued to make a comeback after 3 years of decline. Coal once again become the primary U.S. energy export. Title IV of the Clean Air Act Amendments of 1990 (CAAA90) consists of two phases. Phase I (in effect as of January 1, 1995) set emission restrictions on 110 mostly coal-burning plants in the eastern and midwestem United States. Phase II, planned to begin in the year 2000, places additional emission restrictions on about 1,000 electric plants. As of January 1, 1995, the reformulated gasoline program, also part of the CAAA90, was finally initiated. As a result, this cleaner-burning fuel was made available in areas of the United States that failed to meet the Environmental Protection Agency? s (EPA?s) ozone standards. In 1995, reformulated gasoline represented around 28% of total gasoline sales in the United States. The last commercial nuclear power plant under construction in the United States came on line in 1995. The Tennessee Valley Authority? s (TVA) Watts Bar-l received a low-power operating license from the U.S. Nuclear Regulatory Commission (NRC). The construction permit was granted in 1972. Also, TVA canceled plans to complete construction of three other nuclear plants. In 1995, federal and state governments took steps to deregulate and restructure the electric power industry. The Federal Energy Regulatory Commission (FERC) unanimously approved a proposal to require utilities to open their electric transmission system to competition from wholesale electricity suppliers. California has been at the forefront in the restructuring of the electric utility industry. Plans authorized by the California Public Utility Commission prepare for a free market in electricity to be established by 1998. In 1990, the U.S. Department of Energy (DOE) began reporting statistics on renewable energy consumption. The types and amounts of renewable energy consumed vary by end-use sector, electric utilities and the industrial sector being the primary consumers since 1990. Renewable energy provided 6.83 quads (7.6I) of the total energy consumed in the United States in 1995, compared to 7.1% in 1994. Increasing concern over the emission of greenhouse gases has resulted in exhaustive analysis of U.S. carbon emissions from energy use. Emissions in the early 1990s have already exceeded those projected by the Clinton Administration? s Climate Change Action Plan (CCAP) released in 1994 that was developed to stabilize U.S. greenhouse gas emissions by the year 2000.

Miller, H.; Mui, N.; Pasternak, A.

1997-12-01

102

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.

103

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

104

Numerical laser energy deposition on supersonic cavity flow and sensor placement strategies to control the flow.  

PubMed

In this study, the impact of laser energy deposition on pressure oscillations and relative sound pressure levels (SPL) in an open supersonic cavity flow is investigated. Laser energy with a magnitude of 100?mJ is deposited on the flow just above the cavity leading edge and up to 7?dB of reduction is obtained in the SPL values along the cavity back wall. Additionally, proper orthogonal decomposition (POD) method is applied to the x-velocity data obtained as a result of computational fluid dynamics simulations of the flow with laser energy deposition. Laser is numerically modeled using a spherically symmetric temperature distribution. By using the POD results, the effects of laser energy on the flow mechanism are presented. A one-dimensional POD methodology is applied to the surface pressure data to obtain critical locations for the placement of sensors for real time flow control applications. PMID:24363612

Yilmaz, Ibrahim; Aradag, Selin

2013-01-01

105

The Lorenz energy cycle in simulated rotating annulus flows  

NASA Astrophysics Data System (ADS)

Lorenz energy cycles are presented for a series of simulated differentially heated rotating annulus flows, in the axisymmetric, steady, amplitude vacillating, and structurally vacillating flow regimes. The simulation allows contributions to the energy diagnostics to be identified in parts of the fluid that cannot be measured in experiments. These energy diagnostics are compared with laboratory experiments studying amplitude vacillation, and agree well with experimental time series of kinetic and potential energy, as well as conversions between them. Two of the three major energy transfer paradigms of the Lorenz energy cycle are identified—a Hadley-cell overturning circulation, and baroclinic instability. The third, barotropic instability, was never dominant, but increased in strength as rotation rate increased. For structurally vacillating flow, which matches the Earth's thermal Rossby number well, the ratio between energy conversions associated with baroclinic and barotropic instabilities was similar to the measured ratio in the Earth's mid-latitudes.

Young, R. M. B.

2014-05-01

106

Generalized gradient vector flow external forces for active contours1  

Microsoft Academic Search

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

Chenyang Xu; Jerry L. Prince

1998-01-01

107

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

2011-08-10

108

Energy flow, nutrient cycling, and ecosystem resilience  

Microsoft Academic Search

The resilience, defined here as the speed with which a system returns to equilibrium state following a perturbation, is investigated for both food web energy models and nutrient cycling models. Previous simulation studies of food web energy models have shown that resilience increases as the flux of energy through the food web per unit amount of energy in the steady

DeAngelis

1980-01-01

109

Energy-Efficient, Continuous-Flow Ash Lockhopper  

NASA Technical Reports Server (NTRS)

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

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

1989-01-01

110

Photospheric and sub-photospheric Flows in Active Regions  

NASA Astrophysics Data System (ADS)

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

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

2014-06-01

111

Closed-Loop Active Flow Control Systems: Actuators  

Microsoft Academic Search

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

A. Seifert

112

Radiant energy receiver having improved coolant flow control means  

DOEpatents

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

Hinterberger, H.

1980-10-29

113

Solar activity influence on the Danube river flow, flux, IV.  

NASA Astrophysics Data System (ADS)

The spectral decomposition theorem has been applied for solar activity influence to Danube river flow/flux on a station computation. Following cross-correlations a seven year lag has been found between sunspot umbrae total areas and maximal river flow/flux, as well as a seventeen year lag for minimal Danube river flow/flux. A ?2 test has been applied for the obtained results signification. A short review of previous results concerning total sunspot, total penumbrae and total faculae areas is given.

Jovanovi?, B. D.

1996-10-01

114

Solar Energy Project, Activities: Biology.  

ERIC Educational Resources Information Center

This guide contains lesson plans and outlines of science activities which present concepts of solar energy in the context of biology experiments. Each unit presents an introduction; objectives; skills and knowledge needed; materials; methods; questions; recommendations for further work; and a teacher information sheet. The teacher information…

Tullock, Bruce, Ed.; And Others

115

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

116

Stocks, Flows, and Prospects of Energy  

SciTech Connect

Analyses of future energy systems have typically focused on energy suffi ciency 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

2009-01-01

117

Energy flows in a vortex tube  

Microsoft Academic Search

The energy separation within a vortex tube filled with turbulent compresible fluid is investigated with an order-of-magnitude analysis of the energy equation. The physical processes corresponding to the important terms are: a heat flux due to turbulent mixing of the compressible fluid through radial pressure and temperature gradients, a flux of total energy produced by Archimedean forces, and work fluxes

Alan J. Reynolds

1961-01-01

118

Measurement of energy distribution in flowing hydrogen microwave plasmas  

NASA Technical Reports Server (NTRS)

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

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

1985-01-01

119

Flow of cortical activity underlying a tactile decision in mice.  

PubMed

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

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

2014-01-01

120

Flow of cortical activity underlying a tactile decision in mice  

PubMed Central

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

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

2014-01-01

121

Underwater observations of active lava flows from Kilauea volcano, Hawaii  

USGS Publications Warehouse

Underwater observation of active submarine lava flows from Kilauea volcano, Hawaii, in March-June 1989 revealed both pillow lava and highly channelized lava streams flowing down a steep and unconsolidated lava delta. The channelized streams were 0.7-1.5 m across and moved at rates of 1-3 m/s. The estimated flux of a stream was 0.7 m3/s. Jets of hydrothermal water and gas bubbles were associated with the volcanic activity. The rapidly moving channelized lava streams represent a previously undescribed aspect of submarine volcanism. -Author

Tribble, G. W.

1991-01-01

122

Active Control of Source Sound Power Radiation in Uniform Flow  

NASA Astrophysics Data System (ADS)

Many suggested applications of active noise control involve the presence of a background air flow such as in ventilation ducts, exhaust stacks and the radiation from turbofan engines. This paper is a theoretical study aimed at assessing the effect of a uniform flow on the ability of simple sources actively to control free field sound power radiation. In particular, the minimum sound power radiated by two point volume velocity sources situated in an unbounded uniform fluid which moves with a uniform steady velocity is determined. Also the maximum sound power that can be absorbed by a point volume velocity source from an incident plane wave is determined.

Joseph, P.; Morfey, C. L.; Nelson, P. A.

1998-04-01

123

Optical routing and switching of energy flow in nanostructure systems  

NASA Astrophysics Data System (ADS)

We study optical routing and switching of energy transfer between semiconductor quantum dots and metallic nanostructures. We demonstrate that in the presence of a metallic nanoshell, one can use quantum coherence to direct or switch energy transfer flow from a quantum dot to another quantum dot or to the nanoshell. Our results show that a quantum dot-metallic nanoshell system can act as a bistable energy switch formed via quantum mechanical control of energy transfer processes.

Sadeghi, S. M.

2011-09-01

124

Energy Flow Analysis of Photoactive Yellow Protein  

NASA Astrophysics Data System (ADS)

The signal transduction of photosensory receptors is intimately related to the energy relaxation associated with the relevant functional motion. To understand this energy conversion process, it is useful to analyse the energy flux vector field in a polypeptide chain matrix. Recently, we developed a new formalism for energy flux, JAB, between two different sites A and B in a protein. Flexibility is one of the attractive points of this method, namely, sites A/B can be consisted of an atom or any groups of atoms. In addition, huge computation resource is not required for this method. Since this method is based on the linear response theory, the energy flux, JAB, can be obtained from a classical molecular dynamics simulation trajectory. We can define energy conductivity between the sites A and B in terms of the time-correlation function of JAB. This quantity corresponds to the transport coefficient of heat and potential energy, representing the strength of the direct energetic coupling between the two sites. We applied this method to a photosensory receptor, photoactive yellow protein (PYP). We calculated the energy conductivity between the chromophore and the surrounding amino acid residues, Tyr42, Glu46, Thr50, Arg52, and Tyr98. As a result, we observed the values of energy conductivity decreased in this order. We will discuss the possibility of finding energy transfer pathway in PYP with this method.

Ishikura, Takakazu; Kawaguchi, Kazutomo; Watanabe, Hiroshi; Yamato, Takahisa

2006-03-01

125

Active flow control on a 1:4 car model  

NASA Astrophysics Data System (ADS)

Lift and drag of a passenger car are strongly influenced by the flow field around its rear end. The bluff body geometry produces a detached, transient flow which induces fluctuating forces on the body, affecting the rear axle, which may distress dynamic stability and comfort significantly. The investigations presented here deal with a 1:4 scale model of a simplified test car geometry that produces fluctuating lift and drag due to its strongly rounded rear geometry. To examine the influence of active flow control on this behavior, steady air jets were realized to exhaust from thin slots across the rear in three different configurations. Investigations were performed at and included the capturing of effective integral lift and drag, velocity measurements in the surrounding flow field with Laser Doppler Anemometry, surface pressure measurements and surface oil flow visualization on the rear. The flow field was found to be dominated by two longitudinal vortices, developing from the detachment of the flow at the upper C-pillar positions, and a recirculating, transverse vortex above the rear window. With an air jet emerging from a slot across the surface right below the rear window section, tangentially directed upstream toward the roof section, total lift could be reduced by more than 7 %, with rear axle lift reduction of about 5 % and negligible drag affection (1 %).

Heinemann, Till; Springer, Matthias; Lienhart, Hermann; Kniesburges, Stefan; Othmer, Carsten; Becker, Stefan

2014-05-01

126

Wavelet Representation of Energy Transfer in Turbulent Channel Flow  

NASA Astrophysics Data System (ADS)

Wavelets offer some potential for the analysis of turbulent flow due to their locality and scalability properties. By locality we mean that many wavelets have compact support which enables us to resolve local features of a flow. The scalability allows discrete scales to be analyzed. Thus, in addition to allowing for a natural representation of the classical energy cascade between scales, wavelets also allow a representation of energy flows in physical space. We intend to examine the spatial and scale statistics of turbulent kinetic energy in a turbulent channel flow, using data from direct numerical simulations. We use bi-orthogonal wavelets for wavelet transforms. The behavior of the production, viscous and transfer terms is examined in terms of their variation with both space and scale.

Joshi, Vivek; Rempfer, Dietmar

2004-11-01

127

Energy Flow Diagrams for Teaching Physics Concepts  

Microsoft Academic Search

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

Art Hobson

2004-01-01

128

Active Flow Control on a Boundary-Layer-Ingesting Inlet  

NASA Technical Reports Server (NTRS)

Boundary layer ingestion (BLI) is explored as means to improve overall system performance for Blended Wing Body configuration. The benefits of BLI for vehicle system performance benefit are assessed with a process derived from first principles suitable for highly-integrated propulsion systems. This performance evaluation process provides framework within which to assess the benefits of an integrated BLI inlet and lays the groundwork for higher-fidelity systems studies. The results of the system study show that BLI provides a significant improvement in vehicle performance if the inlet distortion can be controlled, thus encouraging the pursuit of active flow control (AFC) as a BLI enabling technology. The effectiveness of active flow control in reducing engine inlet distortion was assessed using a 6% scale model of a 30% BLI offset, diffusing inlet. The experiment was conducted in the NASA Langley Basic Aerodynamics Research Tunnel with a model inlet designed specifically for this type of testing. High mass flow pulsing actuators provided the active flow control. Measurements were made of the onset boundary layer, the duct surface static pressures, and the mass flow through the duct and the actuators. The distortion was determined by 120 total pressure measurements located at the aerodynamic interface plane. The test matrix was limited to a maximum freestream Mach number of 0.15 with scaled mass flows through the inlet for that condition. The data show that the pulsed actuation can reduce distortion from 29% to 4.6% as measured by the circumferential distortion descriptor DC60 using less than 1% of inlet mass flow. Closed loop control of the actuation was also demonstrated using a sidewall surface static pressure as the response sensor.

Gorton, Susan Althoff; Owens, Lewis R.; Jenkins, Luther N.; Allan, Brian G.; Schuster, Ernest P.

2004-01-01

129

Active Flow Effectors for Noise and Separation Control  

NASA Technical Reports Server (NTRS)

New flow effector technology for separation control and enhanced mixing is based upon shape memory alloy hybrid composite (SMAHC) technology. The technology allows for variable shape control of aircraft structures through actively deformable surfaces. The flow effectors are made by embedding shape memory alloy actuator material in a composite structure. When thermally actuated, the flow effector def1ects into or out of the flow in a prescribed manner to enhance mixing or induce separation for a variety of applications, including aeroacoustic noise reduction, drag reduction, and f1ight control. The active flow effectors were developed for noise reduction as an alternative to fixed-configuration effectors, such as static chevrons, that cannot be optimized for airframe installation effects or variable operating conditions and cannot be retracted for off-design or fail-safe conditions. Benefits include: Increased vehicle control, overall efficiency, and reduced noise throughout all f1ight regimes, Reduced flow noise, Reduced drag, Simplicity of design and fabrication, Simplicity of control through direct current stimulation, autonomous re sponse to environmental heating, fast re sponse, and a high degree of geometric stability. The concept involves embedding prestrained SMA actuators on one side of the chevron neutral axis in order to generate a thermal moment and def1ect the structure out of plane when heated. The force developed in the host structure during def1ection and the aerodynamic load is used for returning the structure to the retracted position. The chevron design is highly scalable and versatile, and easily affords active and/or autonomous (environmental) control. The technology offers wide-ranging market applications, including aerospace, automotive, and any application that requires flow separation or noise control.

Turner, Travis L.

2011-01-01

130

Direct observation of vibrational energy flow in cytochrome c.  

PubMed

Vibrational energy flow in ferric cytochrome c has been examined by picosecond time-resolved anti-Stokes ultraviolet resonance Raman (UVRR) measurements. By taking advantage of the extremely short nonradiative excited state lifetime of heme in the protein (< ps), excess vibrational energy of 20000-25000 cm(-1) was optically deposited selectively at the heme site. Subsequent energy relaxation in the protein moiety was investigated by monitoring the anti-Stokes UVRR intensities of the Trp59 residue, which is a single tryptophan residue involved in the protein that is located close to the heme group. It was found from temporal changes of the anti-Stokes UVRR intensities that the energy flow from the heme to Trp59 and the energy release from Trp59 took place with the time constants of 1-3 and ~8 ps, respectively. These data are consistent with the time constants for the vibrational relaxation of the heme and heating of water reported for hemeproteins. The kinetics of the energy flow were not affected by the amount of excess energy deposited at the heme group. These results demonstrate that the present technique is a powerful tool for studying the vibrational energy flow in proteins. PMID:21974717

Fujii, Naoki; Mizuno, Misao; Mizutani, Yasuhisa

2011-11-10

131

Energy flow and community structure in freshwater ecosystems  

Microsoft Academic Search

The goal of this article is twofold: 1) It aims at providing an overview on some major results obtained from energy flow studies in individuals, populations, and communities, and 2) it will also focus on major mechanisms explaining community structures. The basis for any biological community to survive and establish a certain population density is on the one hand energy

B. Streit

1995-01-01

132

Issues in active flow control: theory, control, simulation, and experiment  

Microsoft Academic Search

The goal of this paper is to provide a perspective on the current status and future directions for active flow-control technology with particular emphasis on oscillatory control. This is not a comprehensive review of the literature; rather, certain issues that are often neglected in studies are highlighted showing their importance or impact on the reported observations and targeted outcomes. Feasible

S. Scott Collis; Ronald D. Joslin; Avi Seifert; Vassilis Theofilis

2004-01-01

133

Stochastic simulation of active grain density in abrasive flow machining  

Microsoft Academic Search

Abrasive flow machining can be applied to an impressive range of finishing operations economically and effectively. Both theoretical and experimental studies of the media topography are greatly hampered by the inherent random nature and the multiplicity of variables. A stochastic simulation model has been developed to determine the active grain density on the media surface which is in contact with

Rajendra K. Jain; V. K. Jain

2004-01-01

134

Multitemporal LIDAR acquisition of active lava flows at Mt. Etna  

NASA Astrophysics Data System (ADS)

Application of airborne-based light detection and ranging (LIDAR) technology in volcanology has spread rapidly over the past few years, being extremely useful for generation of high-resolution digital elevation models (DEM) and mapping eruption products. The raw output of a LIDAR survey consists of the 3D positions of a cloud of points, along with their backscatter intensity signal. The intensity signal must be normalized to account for the uneven geometric factors affecting its values such as the varying distance between the sensor and the reflecting surface during the airborne-based survey. The derived corrected intensity maps are useful for the identification and mapping of different lava flows since intensity values are a function of the age of lava emplacement. Lava flow mapping can also be obtained by the analysis of topographic changes when pre- and post-emplacement topographies are available. At Mt. Etna we carried out airborne LIDAR surveys in 2004, 2005, 2006, 2007 and 2010. The 2004 and 2006 LIDAR acquisitions were performed during ongoing effusive activities allowing precise measurements of the morphological features of active lava channels. The 2006 survey, in particular, was carried out on November 17-18 on the upper slopes of the Valle del Bove (East flank of Mt. Etna) where a compound lava flow field was emplacing. The survey flight was specifically planned as a series of crossings (about 15' apart to cover a period of 2 hours each day) over the flow field to acquire a number of strips (one at each crossing) of the active lava channels. From each strip, a high resolution DEM has been independently derived obtaining a time series of DEMs representing the evolution of this complex lava flow field. Such short period time-series of LIDAR-derived DEMs are very useful to extract detailed information about the dynamics of lava movement, emplacement processes occurring across active lava flow field, and the volumes involved. In analyzing LIDAR data, special effort must be put into three crucial technical aspects: the correction for systematic errors in raw LIDAR data, the DEM-to-DEM co-registration, and the statistical quantification of residual errors. Differences between the different DEMs derived by LIDAR time-series show that the emplacement of flow units is characterized by pulses of lava moving along channel. Lava fluxes have been calculated for several flow units. Volumes and velocities of different pulses are uneven, highlighting a complex non linear emplacement of compound lava flows.

Favalli, M.; Fornaciai, A.; Mazzarini, F.; Tarquini, S.

2012-12-01

135

Active mantle flow and crustal dynamics in southern California  

NASA Astrophysics Data System (ADS)

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 density distribution. Here we quantify the latter by estimating the stresses acting on the base of the crust caused by density-driven flow of the upper mantle. Anomalous density structure is derived from shear wave velocity models (Yang & Forsyth, 2006) and is used to drive instantaneous incompressible viscous upper mantle flow relative to a fixed crust; this allows isolation of stresses acting on the crust. Comparison of results with the finite element codes Abaqus (commercial) and GALE (community- developed) is good. We find that horizontal tractions range from 0 to ~3 MPa and vertical tractions range between approximately -15 to 15 MPa (negative indicating downward, positive upward); Absolute magnitudes depend on the assumed velocity-density scaling relationship but the overall patterns of flow are more robust. Anomalous density beneath the Transverse Ranges, in particular beneath the San Bernardino Mountains and offshore beneath the Channel Islands, drives convergent horizontal tractions and negative vertical tractions on the base of the crust there. Anomalous buoyancy beneath the southern Walker Lane Belt and anomalous density beneath the southern Great Valley create a small convective cell (the Sierra Nevada "drip"), which promotes extension on the eastern edge of the Sierra Nevada block and subsidence of the Great Valley. Favorable comparison with contemporary crustal thickness, heat flow, and surface strain rate indicates that upper mantle flow plays a very important role in active crustal deformation in southern California and much of the non-ideal behavior of this transform boundary can be attributed to the heterogeneous density distribution-driven upper mantle flow.

Fay, N.; Bennett, R.; Spinler, J.

2007-12-01

136

Ecosystem productivity and energy flow of three-hardwood forest  

Microsoft Academic Search

The main characteristics of energy environment, energy products, primary productivity and basic process of energy flow for\\u000a three-hardwood forest (Juglans mandshurica, Fraxinus mandshurica, andPhellodendron amurense) were studied. The research was mainly based on the theory and method of community energetics, dealing with fixed position,\\u000a quantitative test and experimental analysis. The time-space dynamics of sun-radiation in three-hardwood forest were meansured\\u000a and

Lu Zhaohua; Chai Ruihai

1997-01-01

137

Low-Speed Active Flow Control Laboratory Developed  

NASA Technical Reports Server (NTRS)

The future of aviation propulsion systems is increasingly focused on the application of control technologies to significantly enhance the performance of a new generation of air vehicles. Active flow control refers to a set of technologies that manipulate the flow of air and combustion gases deep within the confines of an engine to dynamically alter its performance during flight. By employing active flow control, designers can create engines that are significantly lighter, are more fuel efficient, and produce lower emissions. In addition, the operating range of an engine can be extended, yielding safer transportation systems. The realization of these future propulsion systems requires the collaborative development of many base technologies to achieve intelligent, embedded control at the engine locations where it will be most effective. NASA Glenn Research Center s Controls and Dynamics Technology Branch has developed a state-of-the-art low-speed Active Flow Control Laboratory in which emerging technologies can be integrated and explored in a flexible, low-cost environment. The facility allows the most promising developments to be prescreened and optimized before being tested on higher fidelity platforms, thereby reducing the cost of experimentation and improving research effectiveness.

Culley, Dennis E.; Bright, Michelle M.

2005-01-01

138

Flow of energy in the outer retina in darkness and in light  

PubMed Central

Structural features of neurons create challenges for effective production and distribution of essential metabolic energy. We investigated how metabolic energy is distributed between cellular compartments in photoreceptors. In avascular retinas, aerobic production of energy occurs only in mitochondria that are located centrally within the photoreceptor. Our findings indicate that metabolic energy flows from these central mitochondria as phosphocreatine toward the photoreceptor’s synaptic terminal in darkness. In light, it flows in the opposite direction as ATP toward the outer segment. Consistent with this model, inhibition of creatine kinase in avascular retinas blocks synaptic transmission without influencing outer segment activity. Our findings also reveal how vascularization of neuronal tissue can influence the strategies neurons use for energy management. In vascularized retinas, mitochondria in the synaptic terminals of photoreceptors make neurotransmission less dependent on creatine kinase. Thus, vasculature of the tissue and the intracellular distribution of mitochondria can play key roles in setting the strategy for energy distribution in neurons.

Linton, Jonathan D.; Holzhausen, Lars C.; Babai, Norbert; Song, Hongman; Miyagishima, Kiyoharu J.; Stearns, George W.; Lindsay, Ken; Wei, Junhua; Chertov, Andrei O.; Peters, Theo A.; Caffe, Romeo; Pluk, Helma; Seeliger, Mathias W.; Tanimoto, Naoyuki; Fong, Kimberly; Bolton, Laura; Kuok, Denise L. T.; Sweet, Ian R.; Bartoletti, Theodore M.; Radu, Roxana A.; Travis, Gabriel H.; Zagotta, Willam N.; Townes-Anderson, Ellen; Parker, Ed; Van der Zee, Catharina E. E. M.; Sampath, Alapakkam P.; Sokolov, Maxim; Thoreson, Wallace B.; Hurley, James B.

2010-01-01

139

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

NASA Astrophysics Data System (ADS)

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

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

2001-11-01

140

Energy Flow in the Geomagnetic Tail  

Microsoft Academic Search

MHD closure of the moment equations neglects the divergence of the off-diagonal elements of the stress tensor, Pi , as well as the divergence of heat flux ? q. In the center of the plasma sheet the local ion gyroradius becomes large, and q and Pi become important components of the current sheet energy and momentum balance. Previous work[1] showed

W. Lin; I. Doxas; W. Horton

2002-01-01

141

Energy Balance and Entrainment In Mud Flows  

Microsoft Academic Search

A series of experiments on turbidity currents are presented, using the turbulent energy equation balance with the buoyancy term modelled in terms of the settling velocity. The highly concentrated mud turbidities exhibit non-newtonian effects which may be related to the entrainment experiments of Wolansky and Brush [Tellus 1975]. The influence of slope is also studied in weak and strong entrainment

I. R. Cantalapiedra; M. O. Bezerra; J. M. Redondo

2002-01-01

142

Material and energy flows of a local forest industry system in Finland  

Microsoft Academic Search

Forestry, forest, pulp and paper industries provide important cases for environmental and ecological economics and for corporate environmental management, because of the large quantities of flows of material and energy that are derived from the natural ecosystem. Because of the natural capital intensive nature of its activity, the forest industry also offers a fruitful case study for industrial ecology (IE),

Jouni Korhonen; Ville Niutanen

2003-01-01

143

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.

144

Observations of Flows and Waves in Active Regions: An observational Overview  

NASA Astrophysics Data System (ADS)

In order to understand one of the most intensely studies problem in solar physics i.e. the problem of solar coronal heating, it is mandatory to understand the mass and energy transport in the outer solar atmosphere. Doppler shift measurements in the transition and corona reveal an abundance of plasma flow across a range of temperature having different patterns in different part of the active region, suggesting flow of material. The high resolution imaging observations have revealed that there is an abundance of quasi periodic propagating features which are often interpreted as manifestation of slow magneto-acoustic waves propagating into the atmosphere guided by loop structures. In this talk we will review some recent highlights of the studies of flows and waves and their role in understanding the mass and energy transport in the outer atmosphere.

Tripathi, Durgesh

2012-07-01

145

Inferred flows of electric currents in solar active regions  

NASA Technical Reports Server (NTRS)

Techniques to identify sources of major current systems in active regions and their channels of flow are explored. Measured photospheric vector magnetic fields together with high resolution white light and H-alpha photographs provide the data base to derive the current systems in the photosphere and chromosphere of a solar active region. Simple mathematical constructions of active region fields and currents are used to interpret these data under the assumptions that the fields in the lower atmosphere (below 200 km) may not be force free but those in the chromosphere and higher are. The results obtained for the complex active region AR 2372 are: (1) Spots exhibiting significant spiral structure in the penumbral filaments were the source of vertical currents at the photospheric surface; (2) Magnetic neutral lines where the transverse magnetic field was strongly sheared were channels along which a strong current system flowed; (3) The inferred current systems produced a neutral sheet and oppositely-flowing currents in the area of the magnetic delta configuration that was the site of flaring.

Ding, Y. J.; Hong, Q. F.; Hagyard, M. J.; Deloach, A. C.

1985-01-01

146

Energy flow in the Lake Mendota ecosystem  

Microsoft Academic Search

\\u000a In previous chapters, quantitative data on various components of the Lake Mendota ecosystem have been presented. In the present\\u000a chapter, these data are summarized and incorporated into a tentative model of energy relationships. In order to place all\\u000a data on the same scale, values have been converted to grams of carbon per m3 of lake surface. It is assumed that

Thomas D. Brock

147

U.S. energy flow - 1993  

SciTech Connect

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

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

1994-10-01

148

Ambient wind energy harvesting using cross-flow fluttering  

NASA Astrophysics Data System (ADS)

In this experimental study, we propose and test a bioinspired piezo-leaf architecture which converts wind energy into electrical energy by wind-induced fluttering motion. While conventional fluttering devices are arranged in parallel with the flow direction, here we explore a dangling cross-flow stalk arrangement. This architecture amplifies the vibration by an order of magnitude, making it appropriate for low-cost organic piezomaterials. We fabricated prototypes using flexible piezoelectric materials as stalks and polymer film as leaves. A series of experiments demonstrated a peak output power of approximately 600 ?W and maximum power density of approximately 2 mW/cm3 from a single leaf.

Li, Shuguang; Yuan, Jianping; Lipson, Hod

2011-01-01

149

Active Flow Control: Instrumentation Automation and Experimental Technique  

NASA Technical Reports Server (NTRS)

In investigating the potential of a new actuator for use in an active flow control system, several objectives had to be accomplished, the largest of which was the experimental setup. The work was conducted at the NASA Langley 20x28 Shear Flow Control Tunnel. The actuator named Thunder, is a high deflection piezo device recently developed at Langley Research Center. This research involved setting up the instrumentation, the lighting, the smoke, and the recording devices. The instrumentation was automated by means of a Power Macintosh running LabVIEW, a graphical instrumentation package developed by National Instruments. Routines were written to allow the tunnel conditions to be determined at a given instant at the push of a button. This included determination of tunnel pressures, speed, density, temperature, and viscosity. Other aspects of the experimental equipment included the set up of a CCD video camera with a video frame grabber, monitor, and VCR to capture the motion. A strobe light was used to highlight the smoke that was used to visualize the flow. Additional effort was put into creating a scale drawing of another tunnel on site and a limited literature search in the area of active flow control.

Gimbert, N. Wes

1995-01-01

150

Flow detection of propagating waves with temporospatial correlation of activity  

PubMed Central

Voltage-sensitive dye imaging (VSDI) allows population patterns of cortical activity to be recorded with high temporal resolution, and recent findings ascribe potential significance to their spatial propagation patterns—both for normal cortical processing and in pathologies such as epilepsy. However, analysis of these spatiotemporal patterns has been mostly qualitative to date. In this report, we describe an algorithm to quantify fast local flow patterns of cortical population activation, as measured with VSDI. The algorithm uses correlation of temporal features across space, and therefore differs from conventional optical flow algorithms which use correlation of spatial features over time. This alternative approach allows us to take advantage of the characteristics of fast optical imaging data, which have very high temporal resolution but less spatial resolution. We verify the method both on artificial and biological data, and demonstrate its use.

Takagaki, Kentaroh; Zhang, Chuan; Wu, Jian-Young; Ohl, Frank W.

2011-01-01

151

Boeing active flow control system (BAFCS)-II  

NASA Astrophysics Data System (ADS)

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

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

2001-06-01

152

Conformal curvature flows: from phase transitions to active contours  

Microsoft Academic Search

Abstract: In this paper, we analyze geometric active contour models from a curve evolutionpoint of view and propose some modifications based on gradient flows relative to certainnew feature-based Riemannian metrics. This leads to a novel edge-detection paradigmin which the feature of interest may be considered to lie at the bottom of a potentialwell. Thus an edge-seeking curve is attracted very

S. Kichenasamy; P. Olver; A. Tannenbaum; A. Yezzi

1996-01-01

153

CORRELATED NEURONAL ACTIVITY AND THE FLOW OF NEURAL INFORMATION  

PubMed Central

For years we have known that cortical neurons collectively have synchronous or oscillatory patterns of activity, the frequencies and temporal dynamics of which are associated with distinct behavioural states. Although the function of these oscillations has remained obscure, recent experimental and theoretical results indicate that correlated fluctuations might be important for cortical processes, such as attention, that control the flow of information in the brain.

Salinas, Emilio; Sejnowski, Terrence J.

2010-01-01

154

Conformal Curvature Flows: From Phase Transitions to Active Vision  

Microsoft Academic Search

In this paper, we analyze geometric active contour models from a curve evolutionpoint of view and propose some modifications based on gradient flows relative to certainnew feature-based Riemannian metrics. This leads to a novel edge-detection paradigmin which the feature of interest may be considered to lie at the bottom of a potentialwell. Thus an edge-seeking curve is attracted very naturally

Satyanad Kichenassamy; Arun Kumar

1995-01-01

155

Conformal curvature flows: From phase transitions to active vision  

Microsoft Academic Search

In this paper, we analyze geometric active contour models from a curve evolution point of view and propose some modifications based on gradient flows relative to certain new feature-based Riemannian metrics. This leads to a novel edge-detection paradigm in which the feature of interest may be considered to lie at the bottom of a potential well. Thus an edge-seeking curve

Satyanad Kichenassamy; Arun Kumar; Peter Olver; Allen Tannenbaum; Anthony Yezzi

1996-01-01

156

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

NASA Astrophysics Data System (ADS)

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

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

2014-01-01

157

Magnetotail flow bursts: association to global magnetospheric circulation, relationship to ionospheric activity and direct evidence for localization  

Microsoft Academic Search

A series of bursty bulk flow events (BBFs) were observed by GEOTAIL and WIND in the geomagnetotail. IMP8 at the solar wind showed significant energy coupling into the magnetosphere, while the UVI instrument on POLAR evidenced significant energy transfer to the ionosphere during two substorms. There was good correlation between BBFs and ionospheric activity observed by UVI even when ground

V. Angelopoulos; T. D. Phan; D. E. Larson; F. S. Mozer; R. P. Lin; K. Tsuruda; H. Hayakawa; T. Mukai; S. Kokubun; T. Yamamoto; D. J. Williams; R. W. McEntire; R. P. Lepping; G. K. Parks; M. Brittnacher; G. Germany; J. Spann; H. J. Singer; K. Yumoto

1997-01-01

158

Flow Cytometric Assays for Quantifying Activated Ovine Platelets  

PubMed Central

Ovines are a common animal model for preclinical evaluation of cardiovascular devices including heart valves, endovascular grafts, and ventricular assist devices. Biocompatibility is essential to the success of these devices; however, tools to assess biocompatibility in ovines are limited. To address this need, antibodies that bind to activated human and bovine platelets and annexin V protein were evaluated for potential cross-reactivity to activated ovine platelets. These candidate markers were incubated with stimulated and quiescent ovine whole blood, and binding to platelets was quantified by flow cytometry. Several antihuman CD62P antibodies including one polyclonal antibody, three monoclonal antibodies, and annexin V selectively bound to activated ovine platelets. An assay to quantify platelet microaggregates was also developed. The availability of assays to quantify ovine platelet activation can increase the quality of biocompatibility data obtainable during preclinical development of artificial organs in the ovine model, potentially aiding in the evaluation of design refinements to enhance device biocompatibility.

Johnson, Carl A.; Snyder, Trevor A.; Woolley, Joshua R.; Wagner, William R.

2011-01-01

159

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

PubMed Central

This article uses the ideas of neuroenergetic and neural field theories to detect stimulation-driven energy flows in the brain during face and auditory word processing. In this analysis, energy flows are thought to create the stable gradients of the fMRI weighted summary images. The sources, from which activity spreads in the brain during face processing, were detected in the occipital cortex. The following direction of energy flows in the frontal cortex was described: the right inferior frontal?=?>the left inferior frontal?=?>the triangular part of the left inferior frontal cortex?=?>the left operculum. In the left operculum, a localized circuit was described. For auditory word processing, the sources of activity flows were detected bilaterally in the middle superior temporal regions, they were also detected in the left posterior superior temporal cortex. Thus, neuroenergetic assumptions may give a novel perspective for the analysis of neuroimaging data.

Strelnikov, Kuzma; Barone, Pascal

2012-01-01

160

U.S. energy flow -- 1994  

SciTech Connect

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

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

1995-12-01

161

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

162

A field course based on the community energy flow approach  

Microsoft Academic Search

The concept of community energy flow provides an excellent basis for a field course (a) because simple methods are available for estimating the role of all the interacting components of a community and (6) because results of the series of related investigations can be arranged to provide an acceptable model of community structure and functioning. The study area was part

Colin Townsend; John Phillipson

1977-01-01

163

Research of energy flow in net social ecology system  

Microsoft Academic Search

Network society is a new social form driven by the information technology as a representative of the computer and Internet technology. Network society is similar to the ecological system. Not only is its internal structure a hierarchical structure, according to the whole, but also the energy flow is the important motive mechanism. Based on the ecology theory, with interdisciplinary research

Shan Wang; Zhen-ji Zhang; Xiao-lan Guan; Run-tong Zhang

2010-01-01

164

Energy flow and angular momentum density of nonparaxial Airy beams  

NASA Astrophysics Data System (ADS)

Starting from the vectorial Rayleigh-Sommerfeld formulas, the closed-form expressions of nonparaxial Airy beams are obtained, the paraxial and the nonparaxial energy flow distributions and the angular momentum density distributions of the Airy beams are demonstrated in free space. The effect of the dimensionless perturbation parameter on the nonparaxiality of the Airy beams is discussed.

Deng, Dongmei; Du, Shunli; Guo, Qi

2013-02-01

165

Energy flows management in hybrid vehicles by fuzzy logic controller  

Microsoft Academic Search

Hybrid vehicles for public transportation seem to be a good solution to avoid air pollution and high level of noises in the city centres. The optimal management of energy flows concerned with such vehicles is a difficult task due to the complexity of the whole system including electrical, mechanical, and electrochemical components. In this paper a fuzzy logic based regulator

E. Cerruto; A. Consoli; A. Raciti; A. Testa

1994-01-01

166

Interactions between active particles and dynamical structures in chaotic flow  

NASA Astrophysics Data System (ADS)

Using a simple model, we study the transport dynamics of active, swimming particles advected in a two-dimensional chaotic flow field. We work with self-propelled, point-like particles that are either spherical or ellipsoidal. Swimming is modeled as a combination of a fixed intrinsic speed and stochastic terms in both the translational and rotational equations of motion. We show that the addition of motility to the particles causes them to feel the dynamical structure of the flow field in a different way from fluid particles, with macroscopic effects on the particle transport. At low swimming speeds, transport is suppressed due to trapping on transport barriers in the flow; we show that this effect is enhanced when stochastic terms are added to the swimming model or when the particles are elongated. At higher speeds, we find that elongated swimmers tend be attracted to the stable manifolds of hyperbolic fixed points, leading to increased transport relative to swimming spheres. Our results may have significant implications for models of real swimming organisms in finite-Reynolds-number flows.

Khurana, Nidhi; Ouellette, Nicholas T.

2012-09-01

167

Evolution of energy in flow driven by rising bubbles  

NASA Astrophysics Data System (ADS)

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

Mazzitelli, Irene M.; Lohse, Detlef

2009-06-01

168

Energy Conservation Activity Packet, Grade 6.  

ERIC Educational Resources Information Center

This activity packet for grade 6 is one of 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 six. The packet is divided into two parts and provides the teacher with background information, concepts and…

Bakke, Ruth

169

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

170

Finite element models of piezoelectric actuation for active flow control  

NASA Astrophysics Data System (ADS)

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 such as drag reduction, noise reduction, separation control, mixing enhancement, etc. Two kinds of finite element models, one for the electromechanical field and the other for the fluid-dynamic field, are set up. The analyses are performed with a coupled iterative solver, based on the arbitrarian Lagrangian-Eulerian (ALE) description. A Reynolds-averaged Navier-Stokes Equations (RANS) formulation for the model of turbulent fluid is adopted. The results of some numerical analyses are correlated to an experimental benchmark case founded in literature with the aim to validate the procedure. A sample application to modify the features of separated flow from a backward facing step is described, in which a piezoelectric unimorph actuator is patched on a Euler-Bernoulli beam installed at the upper corner of the step. The numerical model describes the displacement of the incoming shear layer and the velocity perturbation produced by the periodic oscillations of the actuator and how these parameters are related to each other. In order to produce sensible amplitude for the oscillations, the actuator is driven near its natural frequency. A preliminary response analysis to examine the effects of the fluid on the resonant behaviour of the structure is illustrated.

Lampani, L.; Grillo, R.; Gaudenzi, P.

2012-02-01

171

The Onset of Nonlinear Flow in Three-Dimensional Heterogeneous Flow Domains Based on Energy Dissipation Measures  

NASA Astrophysics Data System (ADS)

The onset of nonlinear flow in three-dimensional random disordered porous flow domains was analyzed using participation numbers based on local kinetic energies, and energy dissipation rates computed via non-equilibrium kinetic tensors. A three-dimensional lattice Boltzmann model was used to simulate gravity-driven single-phase flow over a range of Reynolds numbers that included the crossover from linear to nonlinear flow. The simulations results indicated that the kinetic energy participation number characterized the onset of nonlinear flow in terms of transition to a more dispersed (uniform) distribution of kinetic energy densities as the flow rate increased. However, the energy dissipation participation number characterized the onset of nonlinear flow in terms of a transition to a more locally concentrated distribution of energy dissipation densities at higher flows. The flow regime transition characterized by the energy dissipation participation number occurred over a nearly equal or a narrower range of Reynolds numbers compared to the transition characterized by the kinetic energy participation number. The results also revealed that the boundary conditions (periodic vs. no-slip) parallel to the main flow direction have an insignificant effect on the magnitude of the critical Reynolds number, that characterizes the onset of nonlinear effects, although they did influence the spatial correlations of the pore-scale kinetic energy and the energy dissipation densities in all Cartesian directions. Flow domains with periodic boundaries resulted in less-localized (more dispersed) steady-state flows than domains with no-slip boundaries. These results should be useful for designing future experiment like those of Zeria et al. 2005 (Transport in Porous Media, 60:159-181) that would have significant potential implications in diverse fields.

Meakin, P.; Basagaoglu, H.; Succi, S.; Welhan, J.

2005-12-01

172

Boeing active flow control system (BAFCS)-III  

NASA Astrophysics Data System (ADS)

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

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

2002-07-01

173

Hypersonic Flow Control Using Upstream Focused Energy Deposition  

NASA Technical Reports Server (NTRS)

A numerical study of centerline and off-centerline power deposition at a point upstream of a two-dimensional blunt body at Mach 6.5 at 30 km altitude are presented. The full Navier-Stokes equations are used. Wave drag, lift, and pitching moment are presented as a function of amount of power absorbed in the flow and absorption point location. It is shown that wave drag is considerably reduced. Modifications to the pressure distribution in the flow field due to the injected energy create lift and a pitching moment when the injection is off-centerline. This flow control concept may lead to effective ways to improve the performance and to stabilize and control hypersonic vehicles.

Riggins David W.; Nelson, H. F.

1999-01-01

174

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

175

A study of tip clearance flow loss mitigation in a linear turbine cascade using active and passive flow control  

NASA Astrophysics Data System (ADS)

This research examines the use of passive and active blade-mounted flow control to reduce the unwanted losses associated with the blade tip clearance flow in a stationary, open-return, rectilinear turbine cascade at one atmosphere. Traditional flow control techniques have focused on passive methods to improve the aerodynamics in the tip region. However passive methods can create increased heat transfer coefficients on the blade tip and clearance endwall, leading to blade degradation. To improve on these methods, various active flow control methods were designed and tested. The active control was designed to improve the clearance flow aerodynamics without introducing negative heat transfer effects. The flow control methods implemented were single dielectric barrier discharge plasma actuators of various designs and a passive partial suction-side squealer design. The passive squealer was used to benchmark the active designs against a known favorable device. The tip clearance flow was investigated over Reynolds numbers ranging from 5.3x104 to 1.04x105 at clearance heights between one and four percent of axial blade chord. The tip clearance flow was documented using flow visualization and pressure measurements on the blade and endwall surfaces, inlet endwall boundary layer surveys, and wake pressure measurements downstream of the blade. These were carried out in order to understand the receptivity of the tip clearance flow to various types of flow control and the applicable range over which the flow control was effective. The plasma actuator designs caused a reduction in the downstream total pressure loss coefficient ranging between 2% to 12%, depending on Reynolds number, while the passive squealer showed a change of approximately 40%. The results show that the plasma actuator was able to favorably mitigate the adverse effects of the tip clearance flow in a similar manner as the squealer tip, without the drawbacks of the passive method. Plasma actuation was demonstrated as a suitable as a means of reducing the tip clearance flow loss.

van Ness, Daniel Kraus, II

176

Observations of photospheric magnetic fields and shear flows in flaring active regions  

NASA Technical Reports Server (NTRS)

Horizontal flows in the photosphere and subsurface convection zone move the footpoints of coronal magnetic field lines. Magnetic energy to power flares can be stored in the corona if the flows drive the fields far from the potential configuration. Videodisk movies were shown with 0.5 to 1 arcsecond resolution of the following simultaneous observations: green continuum, longitudinal magnetogram, Fe I 5576 A line center (mid-photosphere), H alpha wings, and H alpha line center. The movies show a 90 x 90 arcsecond field of view of an active region at S29, W11. When viewed at speeds of a few thousand times real-time, the photospheric movies clearly show the active region fields being distorted by a remarkable combination of systematic flows and small eruptions of new flux. Magnetic bipoles are emerging over a large area, and the polarities are systematically flowing apart. The horizontal flows were mapped in detail from the continuum movies, and these may be used to predict the future evolution of the region. The horizontal flows are not discernable in H alpha. The H alpha movies strongly suggest reconnection processes in the fibrils joining opposite polarities. When viewed in combination with the magnetic movies, the cause for this evolution is apparent: opposite polarity fields collide and partially cancel, and the fibrils reconnect above the surface. This type of reconnection, driven by subphotospheric flows, complicates the chromospheric and coronal fields, causing visible braiding and twisting of the fibrils. Some of the transient emission events in the fibrils and adjacent plage may also be related.

Tarbell, T.; Ferguson, S.; Frank, Z.; Title, A.; Topka, K.

1988-01-01

177

The energy flow of discrete extended gradient systems  

NASA Astrophysics Data System (ADS)

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

Slijep?evi?, Siniša

2013-07-01

178

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

179

Energy-separating properties of two-phase flow  

Microsoft Academic Search

A new, substantially nondissipative process of energy separation in two-phase flows has been investigated. Mixtures of air with water, kerosene, and an aqueous solution of diethylene glycol were studied at initial pressures of 3–20 bar. It was found that ice was formed in an air-water mixture issuing from a supersonic nozzle, and for a mixture of air with a nonfreezing

A. A. Stoliarov

1976-01-01

180

Energy flow in the Ythan estuary, Aberdeenshire, Scotland  

Microsoft Academic Search

A steady-state energy flow model has been constructed for the Ythan estuary. Nutrient and particulate organic carbon flux has been described in relation to freshwater drainage and tidal action. No rates of retention however, could be provided. Organic C to organic N ratios of detritus vary from 1:14 to 1:200 in the water column, whilst this ratio is 1:8 in

D. Baird; H. Milne

1981-01-01

181

Coupling Nutrient Uptake and Energy Flow in Headwater Streams  

Microsoft Academic Search

Nutrient cycling and energy flow in ecosystems are tightly linked through the metabolic processes of organisms. Greater uptake\\u000a of inorganic nutrients is expected to be associated with higher rates of metabolism [gross primary production (GPP) and respiration\\u000a (R)], due to assimilatory demand of both autotrophs and heterotrophs. However, relationships between uptake and metabolism\\u000a should vary with the relative contribution of

C. S. Fellows; H. M. Valett; C. N. Dahm; P. J. Mulholland; Steve Thomas

2006-01-01

182

Trophic structure and energy flow in a Texas pond  

Microsoft Academic Search

Annual energy flow and mean annual biocontent of eighteen compartments were determined for a 1.0 ha north central Texas pond ecosystem. Annual primary production was 7,789 kcal m-2 yr-1, and community production-to-respiration ratio was 1.49. One-third of annual primary production accumulated on the substrate as silt and sedimentation. Biocontents of four trophic levels in the pond were all of the

W. Michael Childress; Lloyd C. Fitzpatrick; William D. Pearson

1981-01-01

183

OWC wave energy devices with air flow control  

Microsoft Academic Search

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

A. F. de O. Falcão; P. A. P. Justino

1999-01-01

184

A review on flow energy harvesters based on flapping foils  

NASA Astrophysics Data System (ADS)

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

Xiao, Qing; Zhu, Qiang

2014-04-01

185

Active Faulting and Regional Flow in the Corinth Rift  

NASA Astrophysics Data System (ADS)

The Corinth Rift, in western Greece, opens at the yearly rate of 1.5 cm/year with an uplift of its southern shore reaching locally 1 mm/year and elevations reaching 2500 m. The fault system on this southern shore involves a set of parallel fault segments with lengths reaching up to 40 to 50 km and offsets of the order of 1000 m. In the context of the European Corinth Rift Laboratory development, a 1000 m deep borehole has been drilled on the seashore, through the smaller Aegion fault, re-activated during a magnitude 6.2 earthquake, in 1995. The upper 490 m of the well intersects a series of quaternary conglomerates interbedded locally with horizons of calcilutite (calcite mud) which become predominant in the lower 250 m of this section. From 490 m to 690 m a strongly tectonized radiolarite series is encountered till the well penetrates a cretaceous series of fractured limestone, locally karstified. The 15 m thick fault zone, encountered between 750 m and 790 m, within the limestone, has been cored through its whole length and shows crystalline calcite grown in multidecimetric open cavities, within the fault breccia. A one-meter thick siliceous fault gouge made up from the radiolarite is intersected at 760 m. Laboratory permeability measurements yield 9 to 15 10-18 m2 for the calcilutite and 0.9 to 2.0 10-18 m2, for the fault gouge. Production tests conducted during the drilling operation yield a hydraulic conductivity of 10-5 to 10-4 m/s for the upper conglomerates (200m depth) with no artesian flow. The limestone encountered just above the fault, below the radiolarite, is artesian with a 0.5 MPa overpressure and a flow rate equal to 0.7 m3/h. Its hydraulic conductivity has been measured to be about 10-7 m/s. Below the fault, an artesian flow is produced through local karsts observed down to 960 m, with a total flow rate of about 50 m3/h and a 1MPa overpressure, in no flow conditions. The down-hole temperature is only 32° C, for an upper-hole temperature of 17° C. The fault is intersected some 250 m below the local sea-floor in the rift. Hence this active normal faults system acts as a strong hydraulic barrier, east-west oriented, while the mountainous terrain of the southern shore produces a natural hydrostatic load that induces downward flow down to depths, which remains to be ascertained. Geological observations, in the nearby Cyclades islands, some 300 km to the east, suggest meteoritic flow may reach the brittle-ductile transition.

Cornet, F. H.

2003-12-01

186

Energy Flow for a Variable-Gap Capacitor  

NASA Astrophysics Data System (ADS)

When capacitor plates are separated, the capacitor's electrostatic energy either increases or decreases, depending upon whether the charge or the voltage is held constant. For the constant-voltage case, an interesting puzzle can be posed to students: How is it possible that an external agent does positive work on the capacitor while at the same time the capacitor's stored energy decreases? An energy flow diagram, as suggested by Art Hobson's TPT article,1 helps to visualize the movements of energy among different parts of the system. What Richard Feynman calls a ``surprising factor of one-half'' in the expression for the force between capacitor plates confronts students with an additional puzzle to decipher.2

Greene, Nathaniel R.

2005-09-01

187

Magnetotail Flow Bursts: Association to Global Magnetospheric Circulation, Relationship to Ionospheric Activity and Direct Evidence for Localization  

NASA Technical Reports Server (NTRS)

A series of bursty bulk flow events (BBFs) were observed by GEOTAIL and WIND in the geomagnetotail. IMP8 at the solar wind showed significant energy coupling into the magnetosphere, while the UVI instrument of POALR evidenced significant energy transfer to the ionosphere during two substorms. There was good correlation between BBFs and ionospheric activity observed by UVI even when ground magnetic signatures were absent, suggesting that low ionospheric conductivity at the active sector may be responsible for this observation. During the second substorm no significant flux transport was evidenced past WIND in stark contrast to GEOTAIL and despite the small intersatellite separation ((3.54, 2.88, -0.06) Re). Throughout the intervals studied there were significant differences in the individual flow bursts at the two satellites, even during longitudinally extended ionospheric activations. We conclude that the half-scale-size of transport bearing flow bursts is less than 3 Re.

Angelopoulos, V.; Phan, T. D.; Larson, D. E.; Mozer, F. S.; Lin, R. P.; Parks, G. K.; Brittnacher, M. J.; Germany, G. A.; Spann, J. F., Jr.

1998-01-01

188

Limits of tidal energy dissipation by fluid flow in subsea formations  

Microsoft Academic Search

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

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

1999-01-01

189

Solar Energy Project, Activities: General Solar Topics.  

ERIC Educational Resources Information Center

This guide contains lesson plans and outlines of activities which introduce students to concepts and issues relating to solar energy. Lessons frequently presented in the context of solar energy as it relates to contemporary energy problems. Each unit presents an introduction; objectives; necessary skills and knowledge; materials; method;…

Tullock, Bruce, Ed.; And Others

190

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

191

Quantitative assessment of Mycoplasma hemadsorption activity by flow cytometry.  

PubMed

A number of adherent mycoplasmas have developed highly complex polar structures that are involved in diverse aspects of the biology of these microorganisms and play a key role as virulence factors by promoting adhesion to host cells in the first stages of infection. Attachment activity of mycoplasma cells has been traditionally investigated by determining their hemadsorption ability to red blood cells and it is a distinctive trait widely examined when characterizing the different mycoplasma species. Despite the fact that protocols to qualitatively determine the hemadsorption or hemagglutination of mycoplasmas are straightforward, current methods when investigating hemadsorption at the quantitative level are expensive and poorly reproducible. By using flow cytometry, we have developed a procedure to quantify rapidly and accurately the hemadsorption activity of mycoplasmas in the presence of SYBR Green I, a vital fluorochrome that stains nucleic acids, allowing to resolve erythrocyte and mycoplasma cells by their different size and fluorescence. This method is very reproducible and permits the kinetic analysis of the obtained data and a precise hemadsorption quantification based on standard binding parameters such as the dissociation constant K d. The procedure we developed could be easily implemented in a standardized assay to test the hemadsorption activity of the growing number of clinical isolates and mutant strains of different mycoplasma species, providing valuable data about the virulence of these microorganisms. PMID:24498118

García-Morales, Luis; González-González, Luis; Costa, Manuela; Querol, Enrique; Piñol, Jaume

2014-01-01

192

Differential activation and inhibition of RhoA by fluid flow induced shear stress in chondrocytes.  

PubMed

Physical force environment is a major factor that influences cellular homeostasis and remodelling. It is not well understood, however, as a potential role of force intensities in the induction of cellular mechanotransduction. Using a fluorescence resonance energy transfer-based approach, we asked whether activities of GTPase RhoA in chondrocytes are dependent on intensities of flow-induced shear stress. We hypothesized that RhoA activities can be either elevated or reduced by selecting different levels of shear-stress intensities. The result indicates that C28/I2 chondrocytes have increased RhoA activities in response to high shear stress (10 or 20?dyn/cm(2) ), whereas a decrease in activity was seen with an intermediate shear stress of 5?dyn/cm(2) . No changes were seen under low shear stress (2?dyn/cm(2) ). The observed two-level switch of RhoA activities is closely linked to the shear-stress-induced alterations in actin cytoskeleton and traction forces. In the presence of constitutively active RhoA (RhoA-V14), intermediate shear stress suppressed RhoA activities, while high shear stress failed to activate them. In chondrocytes, expression of various metalloproteinases is, in part, regulated by shear and normal stresses through a network of GTPases. Collectively, the data suggest that intensities of shear stress are critical in differential activation and inhibition of RhoA activities in chondrocytes. PMID:23408748

Wan, Qiaoqiao; Kim, Seung Joon; Yokota, Hiroki; Na, Sungsoo

2013-06-01

193

Solar energy education. Renewable energy activities for general science  

SciTech Connect

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

Not Available

1985-01-01

194

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

195

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

NASA Technical Reports Server (NTRS)

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

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

2002-01-01

196

An Energy Principle for Ideal MHD Equilibria with Flows  

SciTech Connect

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

Yao Zhou and Hong Qin

2013-03-11

197

On spectral energy transfer in strongly stratified flows  

NASA Astrophysics Data System (ADS)

The fluid dynamics of many regions of the atmosphere and oceans are characterized by being strongly affected by stable density stratification, but weakly affected by the earth's rotation. This is typical of the open ocean, e.g., on horizontal scales from a few meters up to hundreds of meters. One approach to understanding and predicting such flows is by examining their nonlinear, spectral energy transfer. At horizontal scales strongly affected by stratification, vertical motion as well as the stretching of vertical vorticity is suppressed. In addition the stable stratification supports the propagation of internal waves. These features impose strong constraints on spectral energy transfer. We will present the results of direct numerical simulations of strongly stratified flows with Taylor-Green initialization. The simulations are performed using highly scalable codes run on massively parallel computers; the computational domains are highly anisotropic with up to 2048 X 2048 X 256 grid points. This allows sufficient resolution to examine both the downscale as well as the upscale transfer of energy, both which are found to be dynamically significant.

Riley, James; Vasan, Vishal; Flores, Oscar; Yeung, P. K.

2009-11-01

198

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

2008-03-14

199

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

NASA Astrophysics Data System (ADS)

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

Brzozowski, Daniel; Whalen, Edward A.

2014-04-01

200

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.

201

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

202

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

203

Electric Utility Solar Energy Activities. 1976 Survey.  

National Technical Information Service (NTIS)

The report presents the results of a survey to determine the scope and extent of solar energy projects sponsored by electric utilities. Brief descriptions of the active operations along with information contacts are listed for each participating utility. ...

L. D. Cleary

1977-01-01

204

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

NASA Technical Reports Server (NTRS)

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

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

2003-01-01

205

Dual energy radiography using active detector technology  

Microsoft Academic Search

A new technology has been implemented using an “active-detector” comprised of two computed radiography (CR) imaging plates in a sandwich geometry for dual-energy radiography. This detector allows excellent energy separation, short exposure time, and high signal to noise ratio (SNR) for clinically robust “bone-only” and “soft-tissue only” images with minimum patient motion. Energy separation is achieved by two separate exposures

J. A. Seibert; T. F. Poage; R. E. Alvarez

1996-01-01

206

Coupling Bacterial Activity Measurements with Cell Sorting by Flow Cytometry.  

PubMed

> Abstract A new procedure to investigate the relationship between bacterial cell size and activity at the cellular level has been developed; it is based on the coupling of radioactive labeling of bacterial cells and cell sorting by flow cytometry after SYTO 13 staining. Before sorting, bacterial cells were incubated in the presence of tritiated leucine using a procedure similar to that used for measuring bacterial production by leucine incorporation and then stained with SYTO 13. Subpopulations of bacterial cells were sorted according to their average right-angle light scatter (RALS) and fluorescence. Average RALS was shown to be significantly related to the average biovolume. Experiments were performed on samples collected at different times in a Mediterranean seawater mesocosm enriched with nitrogen and phosphorus. At four sampling times, bacteria were sorted in two subpopulations (cells smaller and larger than 0.25 µm(3)). The results indicate that, at each sampling time, the growth rate of larger cells was higher than that of smaller cells. In order to confirm this tendency, cell sorting was performed on six subpopulations differing in average biovolume during the mesocosm follow-up. A clear increase of the bacterial growth rates was observed with increasing cell size for the conditions met in this enriched mesocosm.http://link.springer-ny.com/link/service/journals/00248/bibs/38n2p180.html PMID:10441710

Servais; Courties; Lebaron; Troussellier

1999-08-01

207

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

208

What is Energy?: Activities and Experiments  

NSDL National Science Digital Library

This website targets teachers, providing them with ideas for simple activities and experiments that can be used to demonstrate concepts related to kinetic and other forms of energy. Each activity and the science concepts involved are clearly delineated. There are also a number of challenge questions suggested to be posted to the students.

2008-06-25

209

What is Energy?: Activities and Experiments  

NSDL National Science Digital Library

This website targets teachers, providing them with ideas for simple activities and experiments that can be used to demonstrate concepts related to kinetic and other forms of energy. Each activity and the science concepts involved are clearly delineated. There are also a number of challenge questions suggested to be posted to the students.

Keep, Wisconsin

2006-07-10

210

Kinetics of Processes Distributed in Activation Energy  

Microsoft Academic Search

The kinetic behavior of systems in which processes occur which are distributed over a range of activation energies is considered. The effects produced by the initial distribution, the order of reaction, and the frequency factor are discussed. Imaginary and actual experimental situations are used to illustrate the large errors which can result when the distribution of the processes in activation

W. Primak

1955-01-01

211

Midtail plasma flows and the relationship to near-Earth substorm activity: A case study  

NASA Technical Reports Server (NTRS)

Recent simulations of magnetotail reconnection have pointed to a link between plasma flows, dipolarization, and the substorm current wedge. In particular, Hesse and Birn (1991) have proposed that earthward jetting of plasma from the reconnection region transports flux into the near-Earth region. At the inner edge of the plasma sheet this flux piles up, producing a dipolarization of the magnetic field. The vorticity produced by the east-west deflection of the flow at the inner edge of the plasma sheet gives rise to field-aligned currents that have region 1 polarity. Thus in this scenario the earthward flow from the reconnection region produces the dipolarization ad the current wedge in a self-consistent fashion. In this study we examine observations made on April 8, 1985 by the Active Magnetospheric Particle Tracer Explorers (AMPTE)/Ion Release Module (IRM), the geosynchronous satellites 1979-053, 1983-019, and 1984-037, and Syowa station, as well as AE. This event is unique because IRM was located near the neutral sheet in the midnight sector for am extended period of time. Ground data show that there was ongoing activity in the IRM local time sector for several hours, beginning at 1800 UT and reaching a crescendo at 2300 UT. This activity was also accompanied by energetic particle variations, including injections, at geosynchronous orbit in the nighttime sector. Significantly, there were no fast flows at the neutral sheet until the great intensification of activity at 2300 UT. At that time, IRM recorded fast eartheard flow simultaneous with a dipolatization of the magetic field. We conclude that while the aforementioned scenario for the creation of the current wedge encounters serious problems explaining the earlier activity, the observations at 2300 UT are consistent with the scenario of Hesse and Birn (1191). On that basis it is argued that the physics of substorms is not exclusively rooted in the development of a global tearing mode. Processes at the inner edge of the cross-tail current that cause a disruption of the current and a consequent dipolarization and current wedge may be unrelated to the formation of a macroscale reconnection region. Thus the global evolution of a substorm is probably a complicated superposition of such processes operating on a very localized scale and a global macroscale process that allows for such things as releasing te energy stored in lobe flux and creation of plasmoids.

Lopez, R. E.; Goodrich, C. C.; Reeves, G. D.; Belian, R. D.; Taktakishvili, A.

1994-01-01

212

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

ERIC Educational Resources Information Center

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

Diaz, Frank M.; Silveira, Jason M.

2013-01-01

213

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

NASA Astrophysics Data System (ADS)

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

Liu, H. L.; Shen, C.

2001-08-01

214

An active flow control scheme for the reduction of cavity pressure in flow-excited Helmholtz resonators  

NASA Astrophysics Data System (ADS)

Flows over cavities acting as flow-excited Helmholtz resonators feature the formation of strong vortices over the cavity orifice, which strength regulates the amplitude of the cavity pressure oscillations. Much is already known about this phenomenon, and models for predicting the magnitude and the frequency of the pressure oscillations are available. Various control devices and schemes have been developed to suppress the oscillations. In particular, active flow control using oscillated leading edge spoilers has been proposed as an alternative to passive spoilers, or flow injection systems. Little is known, however, about the detailed effects of such an active flow control system on the flow field. In the present study, a simple control loop was implemented to adjust the phase between the leading edge spoiler motion and the cavity pressure. The sound pressure inside a resonator was measured over a range of phase differences and spoiler motion amplitudes. It was found using flow visualization that optimally synchronized spoiler motion caused the vortices over the cavity orifice to be less concentrated. The suppression mechanisms were explained using a model based on vortex sound theory.

Park, Jong Beom; Mongeau, Luc

2003-04-01

215

Role of Erythronium americanum Ker. in Energy Flow and Nutrient Dynamics of a Northern Hardwood Forest Ecosystem  

Microsoft Academic Search

The aboveground activity of the spring herb, Erythronium americanum, is restricted to the period between snowmelt and forest canopy development. Its phenology and production capacity closely adapt the species to this temporal niche in northern deciduous forests. While E. americanum has a minor effect on energy flow, it may reduce losses of potassium and nitrogen from the ecosystem during the

Robert N. Muller; F. Herbert Bormann

1976-01-01

216

Fluid flow in fault zones from an active rift  

NASA Astrophysics Data System (ADS)

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

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

2014-05-01

217

A Variable Refrigerant Flow Heat Pump Computer Model in EnergyPlus  

SciTech Connect

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

Raustad, Richard A. [Florida Solar Energy Center

2013-01-01

218

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

Microsoft Academic Search

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

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

2004-01-01

219

Effect of Heart Rate on Regulative Features of the Cortical Activity-Flow Coupling  

Microsoft Academic Search

Objective: Heart rate plays an important role in compensatory conditions of arterial pressure changes. Very little information, however, exists on its role in the dynamic adjustment of stimulated organ perfusion. We studied the influence of heart rate on the activity-flow coupling mechanism which adapts local cerebral blood flow in accordance with cortical activity. Since it does not affect heart rate

B. Rosengarten; C. Budden; S. Osthaus; M. Kaps

2003-01-01

220

Chemical activation through super energy transfer collisions.  

PubMed

Can a molecule be efficiently activated with a large amount of energy in a single collision with a fast atom? If so, this type of collision will greatly affect molecular reactivity and equilibrium in systems where abundant hot atoms exist. Conventional expectation of molecular energy transfer (ET) is that the probability decreases exponentially with the amount of energy transferred, hence the probability of what we label "super energy transfer" is negligible. We show, however, that in collisions between an atom and a molecule for which chemical reactions may occur, such as those between a translationally hot H atom and an ambient acetylene (HCCH) or sulfur dioxide, ET of chemically significant amounts of energy commences with surprisingly high efficiency through chemical complex formation. Time-resolved infrared emission observations are supported by quasi-classical trajectory calculations on a global ab initio potential energy surface. Results show that ?10% of collisions between H atoms moving with ?60 kcal/mol energy and HCCH result in transfer of up to 70% of this energy to activate internal degrees of freedom. PMID:24428264

Smith, Jonathan M; Nikow, Matthew; Ma, Jianqiang; Wilhelm, Michael J; Han, Yong-Chang; Sharma, Amit R; Bowman, Joel M; Dai, Hai-Lung

2014-02-01

221

Multiple mechanisms in the thermally activated plastic flow of tantalum  

SciTech Connect

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

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

1995-06-27

222

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

223

Spectral energy distribution of super-Eddington flows  

NASA Astrophysics Data System (ADS)

Spectral properties of super-Eddington accretion flows are investigated by means of a parallel line-of-sight calculation. The subjacent model, taken from the two-dimensional radiation hydrodynamic simulations by Ohsuga et al. (2005), consists of a disc accretion region and an extended atmosphere with high-velocity outflows. The non-grey radiative transfer equation is solved, including relativistic effects, by applying the flux-limited diffusion approximation. The calculated spectrum is composed of a thermal, blackbody-like emission from the disc which depends sensitively on the inclination angle, and of high-energy X-ray and gamma-ray emission from the atmosphere. We find mild beaming effects in the thermal radiation for small inclination angles. If we compare the face-on case with the edge-on case, the average photon energy is larger by a factor of ~1.7 due mainly to Doppler boosting, while the photon number density is larger by a factor of ~3.7 due mainly to anisotropic matter distribution around the central black hole. This gives an explanation for the observed X-ray temperatures of ULXs which are too high to be explained in the framework of intermediate-mass black holes. While the main features of the thermal spectral component are consistent with more detailed calculations of slim accretion discs, the atmosphere induces major changes in the high-energy part, which cannot be reproduced by existing models. We also conclude that, in order to interpret the observational data properly, simple approaches like the Eddington-Barbier approximation cannot be applied.

Heinzeller, D.; Mineshige, S.; Ohsuga, K.

2006-11-01

224

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

Microsoft Academic Search

Active control of flow over airfoils is currently an area of heightened interest in the aerospace community because of its potential in reducing drag, eliminating separation at high angles of attack, and modulating the aerodynamic forces and moments. We study these possibilities by performing several numerical simulations. Numerical simulations are performed by employing an Unsteady Reynolds-Averaged Navier-Stokes (URANS) equations solver

Jose L. Vadillo

2005-01-01

225

Efficient Ionization Investigation for Flow Control and Energy Extraction  

NASA Technical Reports Server (NTRS)

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

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

2009-01-01

226

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

NASA Technical Reports Server (NTRS)

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

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

1985-01-01

227

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

NASA Technical Reports Server (NTRS)

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

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

1983-01-01

228

Automatic management of energy flows of a stand-alone renewable energy supply with hydrogen support  

Microsoft Academic Search

This work deals with the design and construction of an automation system for controlling the electric energy flows that take place at the continuous current bus (DC Bus) of a wind–solar system with hydrogen support. The automation system is based on a Siemens PLC s7_313C_2DP. This PLC was equipped with a Micro Memory Card (MMC) of 2MB in order to

M. Calderón; A. J. Calderón; A. Ramiro; J. F. González

2010-01-01

229

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.

230

Self-supporting active solar energy system  

Microsoft Academic Search

The article discusses a self-supporting active solar energy system with attention to heat collection, power generation, forced circulation subsystems, and distribution. The system is described in terms of four possible states: (1) sun available and heated fluid in demand, (2) sun available and heated fluid not in demand, (3) sun not available and heated fluid not in demand, and (4)

R. Zakhariya

1977-01-01

231

Solar Energy Project, Activities: Junior High Science.  

ERIC Educational Resources Information Center

This guide contains lesson plans and outlines of science activities which present concepts of solar energy in the context of the junior high science curriculum. Each unit presents an introduction; objectives; skills and knowledge needed; materials; methods; questions; recommendations for further work; and a teacher information sheet. The teacher…

Tullock, Bruce, Ed.; And Others

232

Solar Energy Project, Activities: Chemistry & Physics.  

ERIC Educational Resources Information Center

This guide contains lesson plans and outlines of science activities which present concepts of solar energy in the context of chemistry and physics experiments. Each unit presents an introduction to the unit; objectives; required skills and knowledge; materials; method; questions; recommendations for further work; and a teacher information sheet.…

Tullock, Bruce, Ed.; And Others

233

Solar Energy Project, Activities: Earth Science.  

ERIC Educational Resources Information Center

This guide contains lesson plans and outlines of science activities which present concepts of solar energy in the context of earth science experiments. Each unit presents an introduction; objectives; skills and knowledge needed; materials; method; questions; recommendations for further study; and a teacher information sheet. The teacher…

Tullock, Bruce, Ed.; And Others

234

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

PubMed Central

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

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

2005-01-01

235

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

PubMed

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

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

2014-06-24

236

MARVEL: measured active rotational vibrational energy levels  

NASA Astrophysics Data System (ADS)

An algorithm is proposed, based principally on an earlier proposition of Flaud and co-workers [Mol. Phys. 32 (1976) 499], that inverts the information contained in uniquely assigned experimental rotational-vibrational transitions in order to obtain measured active rotational-vibrational energy levels (MARVEL). The procedure starts with collecting, critically evaluating, selecting, and compiling all available measured transitions, including assignments and uncertainties, into a single database. Then, spectroscopic networks (SN) are determined which contain all interconnecting rotational-vibrational energy levels supported by the grand database of the selected transitions. Adjustment of the uncertainties of the lines is performed next, with the help of a robust weighting strategy, until a self-consistent set of lines and uncertainties is achieved. Inversion of the transitions through a weighted least-squares-type procedure results in MARVEL energy levels and associated uncertainties. Local sensitivity coefficients could be computed for each energy level. The resulting set of MARVEL levels is called active as when new experimental measurements become available the same evaluation, adjustment, and inversion procedure should be repeated in order to obtain more dependable energy levels and uncertainties. MARVEL is tested on the example of the H 217O isotopologue of water and a list of 2736 dependable energy levels, based on 8369 transitions, has been obtained.

Furtenbacher, Tibor; Császár, Attila G.; Tennyson, Jonathan

2007-10-01

237

Application of energy gradient theory in flow instability in a centrifugal pump  

NASA Astrophysics Data System (ADS)

The flow instability in a centrifugal pump is studied using the energy gradient theory. Since the Re is high, the base flow is assumed to be turbulent. The distribution of the energy gradient function K at various flow rates is obtained from numerical simulations. According to the energy gradient method, the area with larger value of K is the place to cause instability and to be of high turbulence intensity. The results show that instability is easier to be excited in the area of impeller outlet and volute tongue. In order to improve the stability of centrifugal pumps working under low flow rate condition, carefulness must be taken in these two key areas.

Dou, H. S.; Jiang, W.

2013-12-01

238

Low Reynolds number flow control via active material actuators  

Microsoft Academic Search

An experimental testbed is described that is used to study the feasibility of control of a class of flows that have low Reynolds numbers. The experimental testbed is comprised of a thin airfoil with a backward facing step machined into the upper surface. A thin PZT composite flap is mounted at the edge of the backward facing step to enable

Bruce F. Carroll; Lou Cattafesta; Andrew J. Kurdila; Carlos Fuentes; Xiang Zhao

2000-01-01

239

Characterization of Active Cooling and Flow Distribution in Microvascular Polymers  

Microsoft Academic Search

Two- and three-dimensional microvascular networks embedded within a polymer fin were fabricated via direct write assembly to demonstrate cooling potential of vascular polymer structures. Thin fin cooling experiments were carried out utilizing water and polyalphaolefin (PAO) oil-based coolant as the working fluids. The surface temperature of the fin was monitored using an infrared camera and flow distribution within the network

Brian D. Kozola; Lyle A. Shipton; Vinay K. Natrajan; Kenneth T. Christensen; Scott R. White

2010-01-01

240

Evidence of active mantle flow beneath South China  

NASA Astrophysics Data System (ADS)

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

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

2013-10-01

241

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

242

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

243

Material and energy flow through the UK iron and steel sector. Part 1: 1954–1994  

Microsoft Academic Search

This paper reports on a historical materials and energy flow analysis of the UK steel sector. The flow of raw materials, steel, steel products and steel scrap are quantified for the period from 1954 to 1994. On the basis of this analysis, the authors calculate the consumption of exergy (or available energy) associated with the UK steel sector taking into

Peter Michaelis; Tim Jackson

2000-01-01

244

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

245

Progress towards sustainability? What the conceptual framework of material and energy flow accounting (MEFA) can offer  

Microsoft Academic Search

Sustainability science analyses society–nature interaction on a variety of spatial and temporal scales. By explaining the link between sustainability and socio-economic material and energy flows as well as with colonization of ecosystems, this paper introduces a conceptual framework for empirical applications featured in other contributions to this special issue. The paper discusses how the proposed material and energy flow accounting

Helmut Haberl; Marina Fischer-Kowalski; Fridolin Krausmann; Helga Weisz; Verena Winiwarter

2004-01-01

246

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

Microsoft Academic Search

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

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

2003-01-01

247

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

248

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

249

Energy-Dependent Octagonal Lattice Boltzmann Modeling for Compressible Flows  

NASA Astrophysics Data System (ADS)

There has been much interest in thermal lattice Boltzmann modeling (TLBM) for compressible flows because of their inherent parallelizeability. Instead of applying CFD techniques to the nonlinear conservation equations, one instead solves a linear BGK kinetic equation. To reduce storage requirements, the velocity space is discretized and lattice geometries are so chosen to minimize the number of degrees of freedom that must be retained in the Chapman-Enskog recovery of the original macroscopic equations. The simplest (and most efficient) TLBM runs at a CFL=1, so that no numerical diffusion or dissipation is introduced. The algorithm involves Lagrangian streaming (shift operator) and purely local operations. Because of the underlying discrete lattice symmetry, the relaxation distributions cannot be Maxwellian and hence the inherent numerical instability problem in TLBM. We are investigating the use of energy-dependent lattices so as to allow simulation of problems of interest in divertor physics, The appeal of TLBM is that it can provide a unified representation for both strongly collisional (‘fluid’) and weakly collisional (‘Monte Carlo’) regimes. Moreover, our TLBM code is more efficiently solved on mulit-PE platforms than the corresponding CFD codes and is readily extended to 3D. MHD can also be handled by TLBM.

Pavlo, Pavol; Vahala, Linda; Vahala, George

2000-10-01

250

Brain energy metabolism and blood flow differences in healthy aging  

PubMed Central

Cerebral metabolic rate of oxygen consumption (CMRO2), cerebral blood flow (CBF), and oxygen extraction fraction (OEF) are important indices of healthy aging of the brain. Although a frequent topic of study, changes of CBF and CMRO2 during normal aging are still controversial, as some authors find decreases of both CBF and CMRO2 but increased OEF, while others find no change, and yet other find divergent changes. In this reanalysis of previously published results from positron emission tomography of healthy volunteers, we determined CMRO2 and CBF in 66 healthy volunteers aged 21 to 81 years. The magnitudes of CMRO2 and CBF declined in large parts of the cerebral cortex, including association areas, but the primary motor and sensory areas were relatively spared. We found significant increases of OEF in frontal and parietal cortices, excluding primary motor and somatosensory regions, and in the temporal cortex. Because of the inverse relation between OEF and capillary oxygen tension, increased OEF can compromise oxygen delivery to neurons, with possible perturbation of energy turnover. The results establish a possible mechanism of progression from healthy to unhealthy brain aging, as the regions most affected by age are the areas that are most vulnerable to neurodegeneration.

Aanerud, Joel; Borghammer, Per; Chakravarty, M Mallar; Vang, Kim; Rodell, Anders B; Jonsdottir, Kristjana Y; M?ller, Arne; Ashkanian, Mahmoud; Vafaee, Manouchehr S; Iversen, Peter; Johannsen, Peter; Gjedde, Albert

2012-01-01

251

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

NASA Technical Reports Server (NTRS)

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

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

1992-01-01

252

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

NASA Astrophysics Data System (ADS)

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

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

2014-08-01

253

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

Microsoft Academic Search

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

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

2008-01-01

254

Active Flow Control on an Industry-Relevant Civil Aircraft Half Model  

Microsoft Academic Search

\\u000a The article presented describes an approach to active flow control by means of pulsed blowing from the flap shoulder in order\\u000a to delay turbulent flow separation in low-speed flows. The experiments were carried out on an industrial low-scale high-lift\\u000a wind tunnel model, a specific landing configuration model employed in the industrial aircraft design process. The results\\u000a verified the concept of

Matthias Bauer; Inken Peltzer; Wolfgang Nitsche; Burkhard Gölling

255

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

256

Evidence of active mantle flow beneath South China (Invited)  

NASA Astrophysics Data System (ADS)

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

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

2013-12-01

257

Dielectric barrier plasma dynamics for active aerodynamic flow control  

NASA Astrophysics Data System (ADS)

The paper investigates the dynamics of a new multiple bipolar multiple Dielectric Barrier Discharges (DBD) actuator using in large-scale flow control. Particle image velocimetry experiments are performed to characteristic the effectiveness of the multiple bipolar DBD plasma actuator. The results show that the mutual interaction between the electrodes, one major disadvantage of traditional DBD characterized by reverse discharge can be entirely avoided, and a constantly accelerating electric wind velocity can be obtained by using the new multiple bipolar DBD plasma actuator.

Hao, JiangNan; Tian, BaLin; Wang, YuLin; Song, YaHui; Pan, ShuCheng; Li, WenFeng

2014-01-01

258

Active Flow Control by Surface Smooth Plasma Actuators  

Microsoft Academic Search

\\u000a Surface smooth plasma actuators were used to control leading-edge flow separation on the flying wing airfoil Eppler E338 for\\u000a angles of attack of up to 12° past stall at low Reynolds numbers. The plasma actuators were operated over a range of free-stream\\u000a speeds from 2.2 to 6.6 m\\/s giving chord Reynolds numbers from 26K to 79K. The plasma actuators produced

B. Göksel; I. Rechenberg

259

Blood flow in branching circulatory systems during rest and activity  

Microsoft Academic Search

On the basis of simple physical considerations the blood flow in a branching circulatory system is studied. The case of two\\u000a groups of parallel vessels is treated. The vessels of the same group are supposed to be identical. The resistance of each\\u000a group is determined by the resistance of each vessel in the group and by the number of vessels

George Karreman

1953-01-01

260

Energy Expenditure During Extravehicular Activity Through Apollo  

NASA Technical Reports Server (NTRS)

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

Paul, Heather L.

2011-01-01

261

Energy Expenditure During Extravehicular Activity Through Apollo  

NASA Technical Reports Server (NTRS)

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

Paul, Heather L.

2012-01-01

262

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

2013-10-01

263

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

NASA Astrophysics Data System (ADS)

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

Vadillo, Jose L.

264

Conical Euler Analysis and Active Roll Suppression for Unsteady Vortical Flows About Rolling delta Wings.  

National Technical Information Service (NTIS)

A conical Euler code was developed to study unsteady vortex-dominated flows about rolling, highly swept delta wings undergoing either forced motions or free-to-roll motions that include active roll suppression. The flow solver of the code involves a multi...

E. M. Lee-rausch J. T. Batina

1993-01-01

265

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

Microsoft Academic Search

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

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

2010-01-01

266

Flow-Induced Platelet Activation in Bileaflet and Monoleaflet Mechanical Heart Valves  

Microsoft Academic Search

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

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

2004-01-01

267

PHOTOGRAMMETRIC IMAGE SEQUENCE PROCESSING TO DETERMINE CHANGE IN ACTIVE LAVA FLOWS  

Microsoft Academic Search

Understanding the processes involved with the advance of lava flows is critical for improving hazard assessments at many volcanoes. Here, we describe the application of computer vision and oblique photogrammetric techniques to visible and thermal images of active lavas in order to investigate flow processes at Mount Etna, Sicily and in Hawaii. Photogrammetric surveys were carried out to produce repeated

S. Robson; M. R. James

268

A dual active-restrictive approach to incorporating environmental flow targets into existing reservoir operation rules  

Microsoft Academic Search

Environmental flow schemes may be implemented through active or restrictive strategies. The former may be applied via reservoir releases, and the latter can be executed by reducing water demands. We present a dual active-restrictive approach to devising the optimal reservoir operation rules that aim to secure off-stream water supplies while maximizing environmental benefits. For the active part, a multicomponent environmental

Jenq-Tzong Shiau; Fu-Chun Wu

2010-01-01

269

Active Control by Conservation of Energy Concept  

NASA Technical Reports Server (NTRS)

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

Maestrello, Lucio

2000-01-01

270

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

271

Broadening of activity with flow across neural structures  

PubMed Central

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

Lytton, William; Orman, Rena; Stewart, Mark

2009-01-01

272

Broadening of activity with flow across neural structures.  

PubMed

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

Lytton, William W; Orman, Rena; Stewart, Mark

2008-01-01

273

Volumetric methods for evaluating irreversible energy losses and entropy production with application to bioengineering flows  

NASA Astrophysics Data System (ADS)

Methods for calculating irreversible energy losses and rates of heat transfer from computational fluid dynamics solutions using volume integrations of energy dissipation functions contrast with the more usual approach of performing first law energy balances over the boundaries of a flow domain. Advantages of the approach are that the estimates involve the whole flow domain, and are hence based on more information than would otherwise be used, and that the energy dissipation function allows for detailed assessment of the mechanisms and regions of energy loss.The research was motivated by a need to clarify energy losses by haemodynamics in the greater vessels of the human body, in particular, the Fontan connection. For this application irreversible energy losses were calculated using the viscous dissipation function. Streamwise integration of the viscous dissipation function is also used to explore the ways in which different flow structures contribute to energy losses.

Moyle, Keri; Mallinson, Gordon; Cowan, Brett

2006-04-01

274

Energy flow and nutrient cycling in salamander populations in the Hubbard Brook Experimental Forest, New Hampshire  

Microsoft Academic Search

Energy flow through salamander populations in the Hubbard Brook Ecosystem is about 11,000 kcal\\/ha yr (=46,000 kJ\\/ha yr). This is approx. = 0.02% of the net primary productivity, and is approx. = 20% of the energy flow through bird and mammal populations. Salamanders are efficient (60%) at converting ingested energy into new tissue and produce more new tissue annually than

T. M. Burton; G. E. Likens

1975-01-01

275

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

276

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

277

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

NASA Astrophysics Data System (ADS)

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

Herbert, Corentin

2014-03-01

278

Active Feedback Control of a Web Flutter Using Flow Control Devices  

NASA Astrophysics Data System (ADS)

This paper develops a non-contact active feedback control of web flutter in a narrow passage by using movable plates set at inlet and outlet of the passage. The strategy of this active feedback control is based on the flow-control which cancels the exciting fluid force acting on the web, i.e., cancels the self-excited feedback mechanism. In this paper, suppression of the web flutter by the active feedback control is demonstrated experimentally. In the experiments, a web (film), as a controlled object, is subjected to air flow in a narrow passage. The web flutter occurs to the web in the translational motion over the critical flow velocity. And the web flutter is actively controlled and suppressed by the movable plate motion which changes the air flow in the passage. The critical flow velocity under controlled condition is examined with changing the controller gain and phase-shift between the web motion and the movable plate motion. As a result, it is indicated that the active feedback control increases the critical flow velocity, and suppress the web flutter effectively. Moreover, the control performance is examined experimentally, and stabilization mechanism by the active feedback control is discussed.

Hayashi, Yusuke; Watanabe, Masahiro; Hara, Kensuke

279

Monocular distance estimation from optic flow during active landing maneuvers.  

PubMed

Vision is arguably the most widely used sensor for position and velocity estimation in animals, and it is increasingly used in robotic systems as well. Many animals use stereopsis and object recognition in order to make a true estimate of distance. For a tiny insect such as a fruit fly or honeybee, however, these methods fall short. Instead, an insect must rely on calculations of optic flow, which can provide a measure of the ratio of velocity to distance, but not either parameter independently. Nevertheless, flies and other insects are adept at landing on a variety of substrates, a behavior that inherently requires some form of distance estimation in order to trigger distance-appropriate motor actions such as deceleration or leg extension. Previous studies have shown that these behaviors are indeed under visual control, raising the question: how does an insect estimate distance solely using optic flow? In this paper we use a nonlinear control theoretic approach to propose a solution for this problem. Our algorithm takes advantage of visually controlled landing trajectories that have been observed in flies and honeybees. Finally, we implement our algorithm, which we term dynamic peering, using a camera mounted to a linear stage to demonstrate its real-world feasibility. PMID:24855045

van Breugel, Floris; Morgansen, Kristi; Dickinson, Michael H

2014-06-01

280

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

281

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 (burning),…

Wichita Unified School District 259, KS.

282

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

NASA Technical Reports Server (NTRS)

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

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

2004-01-01

283

On Analysis of Flow Fields of a River for Water Activity Preferred by Children  

NASA Astrophysics Data System (ADS)

An objective of this study was to analyze which flow fields of a river were preferred by children for their water activities through a field research at the middle of the Doki River located in Manno Town, Kagawa Prefecture. In order to analyze the children' preferences on each age group for flow fields to play in water, the Jacobs' Indices were calculated by flow fields played by children classified by water depth and velocity. The following findings are obtained; 1) In case of under six years old, flow fields that water depth was less than 30 cm and water velocity was less than 0.1 cm/s were selected specifically for their activities. 2) Over 7 years old children come to prefer deeper and faster flow fields.

Kakudo, Hirofumi; Nishiyama, Mika

284

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

285

Energy and Man's Environment Activity Guide: An Interdisciplinary Teacher's Guide to Energy and Environmental Activities, Section Four - Impacts of Energy.  

ERIC Educational Resources Information Center

This publication presents the activities pertaining to the fourth goal of this activity guide series. The activities in this publication focus on the socioeconomic effects of energy uses and crises and the understandings needed to assess those effects. These materials are appropriate for middle school and junior high school students. These…

Jones, John, Ed.

286

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

287

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

288

Linear stability and energy growth of viscosity stratified flows  

NASA Astrophysics Data System (ADS)

The non-normality of the Orr-Sommerfeld equation leads to the possibility of disturbance growth even though all eigenvalues are stable. In single-fluid flow the disturbance growth converges to a limit once the number of modes exceeds a minimum number. In the case of a two-fluid flow, however, convergence is not found. The problem of nonconvergence is due to the presence of the interface and the corresponding interfacial mode. The interface is replaced with a miscible layer of variable viscosity. When the thickness of the miscible layer is approximately equal to the thickness of the critical layer, the flow resembles two-fluid flow and one of the modes starts behaving like the interfacial mode.

Malik, Satish V.; Hooper, Alison P.

2005-02-01

289

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

NASA Technical Reports Server (NTRS)

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

Offenhaeuser, F.

1987-01-01

290

Effect of concentrated energy deposition on the aerodynamic drag of a blunt body in hypersonic flow  

NASA Astrophysics Data System (ADS)

Experimental results on the effect of energy deposition using an electric arc discharge, upstream of a 60° half angle blunt cone configuration in a hypersonic flow stream is reported. Investigations involving drag measurements and high speed Schlieren flow visualization have been carried out in a hypersonic shock tunnel using air and argon as the test gases; and an unsteady drag reduction of about 50% (maximum reduction) has been observed in the energy deposition experiments done in argon environment. These studies also show that the effect of discharge on the flow field is more pronounced in argon environment as compared to air, which confirms that thermal effects are mainly responsible for flow alteration with discharge. It has also been observed that the interaction of the hypersonic flow with the discharge filament results in the development of an unsteady flow field.

Satheesh, K.; Jagadeesh, G.

2007-03-01

291

DEVELOPMENT OF A LOW COST INFERENTIAL NATURAL GAS ENERGY FLOW RATE PROTOTYPE RETROFIT MODULE  

Microsoft Academic Search

In 1998, Southwest Research Institute began a multi-year project to develop a working prototype instrument module for natural gas energy measurement. The module will be used to retrofit a natural gas custody transfer flow meter for energy measurement, at a cost an order of magnitude lower than a gas chromatograph. Development and evaluation of the prototype energy meter in 2002-2003

E. Kelner; D. George; T. Morrow; T. Owen; M. Nored; R. Burkey; A. Minachi

2005-01-01

292

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

293

Gas secondary flow: A key factor in the future of coal energy  

Microsoft Academic Search

The increased need for finding alternative energy sources other than petroleum and natural gas initiated extensive research work for extraction of energy from wind, water, ocean, solar, nuclear geothermal, hydrogen and coal. This paper is devoted to coal energy. It discusses one of the serious problems encountered in coal-fired gas turbines; namely erosion and how gas secondary flow has a

A. F. Abel Azim El-Sayed; W. T. Ruuleau

1983-01-01

294

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

NASA Astrophysics Data System (ADS)

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

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

2013-12-01

295

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

NASA Astrophysics Data System (ADS)

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

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

2014-12-01

296

Dissociation of spikes, synaptic activity, and activity-dependent increments in rat cerebellar blood flow by tonic synaptic inhibition.  

PubMed

Functional neuroimaging relies on the robust coupling between neuronal activity, metabolism and cerebral blood flow (CBF) to map the brain, but the physiological basis of the neuroimaging signals is still not well understood. Here we applied a pharmacological approach to separate spiking activity, synaptic activity, and the accompanying changes in CBF in rat cerebellar cortex. We report that tonic synaptic inhibition achieved by topical application of gamma-aminobutyric acid type A (GABAA) (muscimol) or GABAB (baclofen) receptor agonists abolished or reduced spontaneous Purkinje cell spiking activity without affecting basal CBF. The magnitude of CBF responses evoked by climbing fiber stimulation decreased gradually over time after exposure to muscimol, being more pronounced in the superficial than in the deep cortical layers. We provide direct evidence in favor of a laminar-specific regulation of CBF in deep cortical layers, independent of dilatation of surface vessels. With prolonged exposure to muscimol, activity-dependent CBF increments disappeared, despite preserved cerebrovascular reactivity to adenosine and preserved local field potentials (LFP). This dissociation of CBF and LFPs suggests that CBF responses are independent of extracellular synaptic currents that generate LFPs. Our work implies that neuronal and vascular signals evoked by glutamatergic pathways are sensitive to synaptic inhibition, and that local mechanisms independent of transmembrane synaptic currents adjust flow to synaptic activity in distinct cortical layers. Our results provide fundamental insights into the functional regulation of blood flow, showing important interference of GABAA receptors in translating excitatory input into blood flow responses. PMID:14673091

Caesar, Kirsten; Thomsen, Kirsten; Lauritzen, Martin

2003-12-23

297

Numerical investigations on flow behaviour and energy separation in Ranque–Hilsch vortex tube  

Microsoft Academic Search

A three-dimensional numerical model of Ranque–Hilsch vortex tube has been developed using the commercial CFD code (Star-CD) to analyze the flow parameters and energy separation mechanism inside the tube. Investigations have been done on the variation of fluid properties and flow parameters as the fluid particles progress in the flow field by tracking different particles exiting through the hot and

Upendra Behera; P. J. Paul; K. Dinesh; S. Jacob

2008-01-01

298

Segmentation and tracking in echocardiographic sequences: active contours guided by optical flow estimates  

NASA Technical Reports Server (NTRS)

This paper presents a method for segmentation and tracking of cardiac structures in ultrasound image sequences. The developed algorithm is based on the active contour framework. This approach requires initial placement of the contour close to the desired position in the image, usually an object outline. Best contour shape and position are then calculated, assuming that at this configuration a global energy function, associated with a contour, attains its minimum. Active contours can be used for tracking by selecting a solution from a previous frame as an initial position in a present frame. Such an approach, however, fails for large displacements of the object of interest. This paper presents a technique that incorporates the information on pixel velocities (optical flow) into the estimate of initial contour to enable tracking of fast-moving objects. The algorithm was tested on several ultrasound image sequences, each covering one complete cardiac cycle. The contour successfully tracked boundaries of mitral valve leaflets, aortic root and endocardial borders of the left ventricle. The algorithm-generated outlines were compared against manual tracings by expert physicians. The automated method resulted in contours that were within the boundaries of intraobserver variability.

Mikic, I.; Krucinski, S.; Thomas, J. D.

1998-01-01

299

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

NASA Technical Reports Server (NTRS)

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

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

1997-01-01

300

Control of hepatic arterial blood flow: independence from liver metabolic activity.  

PubMed

This investigation tested the hypothesis that hepatic arterial blood flow is not dependent on hepatic metabolism, but rather is controlled in a manner that tends to maintain total hepatic blood flow constant. Cats anesthetized with pentobarbital sodium received SKF 525 A or 2,4-dinitrophenol (DNP), respectively, to inhibit or stimulate metabolism. Blood flows and oxygen uptake of the liver and gut were determined by use of a hepatic venous long circuit and noncannulating electromagnetic recording of hepatic arterial blood flow. In both sets of experiments the hepatic arterial blood flow. In both sets of experiments the hepatic artery constricted sufficiently to offset elevated portal venous blood flow, thereby maintaining total hepatic blood flow constant. The reduced hepatic arterial conductance occurred with DNP despite elevated metabolic rate and reduced oxygen in the portal and hepatic veins. Altered gut metabolism correlated with altered vascular conductance in the gut; hepatic arterial conductance changes did not correlate with changes in liver metabolic activity. The data confirmed the hypothesis. It is suggested that for hormonal homeostatis it is essential that total hepatic blood flow be regulated because hepatic clearance is flow dependent. PMID:7425146

Lautt, W W

1980-10-01

301

Energy confinement studies in the tandem mirror experiment (TMX): Power flow  

Microsoft Academic Search

Using the measured plasma densities and energies, the flow of power between the different particle species and regions of the tandem mirror experiment (TMX) is analyzed. The power flow is described by a simple classical model modified to include: (1) a halo of cool plasma that reduces end-cell ion losses due to charge exchange on background gas, (2) instability heating

D. P. Grubb; S. L. Allen; T. A. Casper; J. F. Clauser; F. H. Coensgen; R. H. Cohen; D. L. Correll; W. C. Cummins; J. C. Davis; R. P. Drake; J. H. Foote; A. H. Futch; R. K. Goodman; G. E. Gryczkowski; E. B. Hooper Jr.

1983-01-01

302

Information and Data Flows in Societal Problem Areas: Focus-Energy.  

National Technical Information Service (NTIS)

This report addresses the problem of how scientific and technical information and data (STID) flow from research into decision making in efforts to solve important societal problems. Two case studies of STID flows in the area of energy provide an empirica...

J. E. Freeman J. P. Kottenstette P. M. Gatseos

1977-01-01

303

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

PubMed

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 ( approximately 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. PMID:16099071

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

2005-10-01

304

NEWQUE with Per-flow Scheduling: Performance improvement of Active Queue Management algorithm  

Microsoft Academic Search

In order to design the congestion control scheme in the routers, an Active Queue Management (AQM) is proposed. This is used to control congestion at the router, where packets are dropped before queue becomes full. A new framework of AQM, namely NEWQUE with Per-flow Scheduling (PerNEWQUE) active queue management algorithm supporting explicit congestion notification (ECN), is proposed by extending scheduling

V. Santhi; A. M. Natarajan

2010-01-01

305

Experimental investigation into cutting forces and active grain density during abrasive flow machining  

Microsoft Academic Search

It is important to know cutting force components and active grain density during abrasive flow machining (AFM) as this information could be used to evaluate the mechanism involved in AFM. The results show that cutting force components and active grain density govern the surface roughness produced during AFM process. In this paper, an attempt has been made to study the

V. K Gorana; V. K Jain; G. K Lal

2004-01-01

306

Multiobjective genetic algorithm conjunctive use optimization for production, cost, and energy with dynamic return flow  

NASA Astrophysics Data System (ADS)

A multiobjective genetic algorithm is used to optimize a water conjunctive use problem.Water production, cost, and energy production are optimized simultaneously.Optimized simultaneously are significant nonlinear groundwater and surface water flow.

Peralta, Richard C.; Forghani, Ali; Fayad, Hala

2014-04-01

307

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. 8 cm×8 cm) 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 (0.016-300 Hz 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; Özerdem, Mehmet Siraç; Bayrak, Coskun; Mendi, Engin

2013-12-01

308

Energy Conservation Activities for the Classroom K-12.  

ERIC Educational Resources Information Center

After a brief introduction entitled "Where Does the Energy We Use Come From," this unit presents 86 activities. Each activity gives the title, concept, objectives, subject area, level, time involved, materials needed, procedures, and related career activities. Topics cover everything from housing insulation to alternate sources of energy to energy

Kentucky Dept. of Energy, Frankfort.

309

Effects of uncertain fuel costs on fossil fuel and electric energy flows in the US  

Microsoft Academic Search

To explore the effects of uncertain fuel costs on the bulk energy flows in the US, we introduce stochastic fuel costs in a\\u000a generalized network flow model of the integrated electric energy system, including coal, natural gas, and electricity generation.\\u000a The fuel costs are modeled as discretely distributed random variables. A rolling two-stage recourse stochastic programming\\u000a approach is employed to

Yan Wang; Sarah M. Ryan

2010-01-01

310

Energy Flows and Maximum Power on an Evolutionary Ecological Network Model  

Microsoft Academic Search

Energy flows in ecological systems which are determined by the structure of the ecological network influence the evolution\\u000a of the network itself. The total system energy throughflow as an important indicator of the co-evolution of network and flows\\u000a in the ecosystem can be maximized spontaneously according to the maximum power principle. This principle should be thought\\u000a as an emergent and

Jiang Zhang

2007-01-01

311

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

312

Intensification of mixing of parallel compressible flows using a localized pulse-periodic energy supply  

NASA Astrophysics Data System (ADS)

The possibility of intensification of the mixing of supersonic and subsonic low-density gas jets that interact with an oblique shock with an ambient cocurrent supersonic flow using a localized pulse-periodic energy supply is demonstrated by means of numerical simulation. It is shown how an energy source located in front of the shock at the jet axis and also in an external flow affects the generation of large-scale vortex structures that favor the mixing process intensification.

Zheltovodov, A. A.; Pimonov, E. A.

2013-11-01

313

Development of new vibration energy flow analysis software and its applications to vehicle systems  

Microsoft Academic Search

The Energy flow analysis (EFA) offers very promising results in predicting the noise and vibration responses of system structures in medium-to-high frequency ranges. We have developed the Energy flow finite element method (EFFEM) based software, EFADSC++ R4, for the vibration analysis. The software can analyze the system structures composed of beam, plate, spring-damper, rigid body elements and many other components

D.-J. Kim; S.-Y. Hong; Y.-H. Park

2005-01-01

314

Energy flow in high speed perforation and cutting  

SciTech Connect

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

van Thiel, M.

1980-10-07

315

Active control of asymmetric conical flow using spinning and rotatory oscillations  

NASA Technical Reports Server (NTRS)

The effectiveness of active control on asymmetric flows around circular cones is investigated computationally using cone spinning and rotatory oscillation around its axis. The investigation uses the time-accurate solution of the unsteady, compressible, full Navier-Stokes equations with the implicit, upwind, flux-difference splitting, finite-volume scheme. The present solutions are obtained under the locally-conical-flow assumption in order to understand the flow physics using very fine grids for reasonable flow resolution at low computational cost. For all the computational solutions, a grid of 241 x 81 x 2 points in the wrap-around, normal and axial directions, respectively, is used. The grid is spinning or oscillating rigidly with the cone according to its motion and the kinematical and dynamical boundary conditions are modified accordingly. The computational applications include the effects of uniform spinning rates and periodic rotatory oscillations at different amplitudes and frequencies on the flow asymmetry.

Kandil, Osama A.; Sharaf El-Din, Hazem H.; Liu, C. H.

1993-01-01

316

Evolution of elliptic and triangular flow as a function of beam energy in a hybrid model  

NASA Astrophysics Data System (ADS)

Elliptic flow has been one of the key observables for establishing the finding of the quark-gluon plasma (QGP) at the highest energies of Relativistic Heavy Ion Collider (RHIC) and the Large Hadron Collider (LHC). As a sign of collectively behaving matter, one would expect the elliptic flow to decrease at lower beam energies, where the QGP is not produced. However, in the recent RHIC beam energy scan, it has been found that the inclusive charged hadron elliptic flow changes relatively little in magnitude in the energies between 7.7 and 39 GeV per nucleon-nucleon collision. We study the collision energy dependence of the elliptic and triangular flow utilizing a Boltzmann + hydrodynamics hybrid model. Such a hybrid model provides a natural framework for the transition from high collision energies, where the hydrodynamical description is essential, to smaller energies, where the hadron transport dominates. This approach is thus suitable to investigate the relative importance of these two mechanisms for the production of the collective flow at different values of beam energy. Extending the examined range down to 5 GeV per nucleon-nucleon collision allows also making predictions for the CBM experiment at FAIR.

Auvinen, J.; Petersen, H.

2014-04-01

317

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

2013-01-01

318

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

319

Analysis of Active Lava Flows on Kilauea Volcano, Hawaii, Using SIR-C Radar Correlation Measurements  

NASA Technical Reports Server (NTRS)

Precise eruption rates of active pahoehoe lava flows on Kilauea volcano, Hawaii, have been determined using spaceborne radar data acquired by the Space Shuttle Imaging Radar-C (SIR-C). Measurement of the rate of lava flow advance, and the determination of the volume of new material erupted in a given period of time, are among the most important observations that can be made when studying a volcano.

Zebker, H. A.; Rosen, P.; Hensley, S.; Mouginis-Mark, P. J.

1995-01-01

320

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

321

Flow rate and duty cycle effects in lysis of Chlamydomonas reinhardtii using high-energy pulsed focused ultrasound.  

PubMed

To consider microalgae lipid biofuel as a viable energy source, it is a necessity to maximize algal cell lysis, lipid harvest, and thus biofuel production versus the energy used to lyse the cells. Previous techniques have been to use energy consumptive ultrasound waves in the 10-40?kHz range in a stationary exposure environment. This study evaluated the potential of using 1.1?MHz ultrasound pulses in a new flow through type chamber on Chlamydomonas reinhardtii as a model organism for cell breakage. The ultrasound was generated using a spherically focused transducer with a focal length of 6.34?cm and an active diameter of 6.36?cm driven by 20 cycle sine-wave tone bursts at varied pulse repetition frequencies. First, variations in flow rate were examined at a constant duty cycle of 3.6%. After assessing flow rates, the duty cycle was varied to further explore the dependence on the tone burst parameters. Cell lysis was assessed by quantifying protein and chlorophyll release into the supernatant as well as by lipid extractability. Appropriate flow rates with higher duty cycles led to statistically significant increases in cell lysis relative to controls and other exposure conditions. PMID:24916410

Riesberg, Grant; Bigelow, Timothy A; Stessman, Dan J; Spalding, Martin H; Yao, Linxing; Wang, Tong; Xu, Jin

2014-06-01

322

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

NASA Technical Reports Server (NTRS)

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

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

2009-01-01

323

Evidence of Mechanically Activated Processes in Slow Granular Flows  

NASA Astrophysics Data System (ADS)

We study how a shear band in a granular medium dramatically changes the mechanical behavior of the material further in the non sheared region. To this end, we carry out a microrheology experiment, where a constant force F is applied to a small rod immersed outside the shear band. In the absence of a shear band, a critical force Fc is necessary to move the intruder. When a shear band exists, the intruder moves even for a force F less than the critical force Fc. We systematically study how the creep velocity Vcreep of the rod varies with Fc-F and with the distance to the shear band, and show that the behavior can be described by an Eyring-like activated process.

Reddy, K. A.; Forterre, Y.; Pouliquen, O.

2011-03-01

324

The Limit of Free Magnetic Energy in Active Regions  

NASA Technical Reports Server (NTRS)

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

Moore, Ron; Falconer, David; Sterling, Alphonse

2012-01-01

325

Flow cytometric assessment of the antimicrobial activity of essential oils against Listeria monocytogenes  

Microsoft Academic Search

Flow cytometry was applied to assess the antimicrobial activity of oregano, thyme and cinnamon essential oils against Listeria monocytogenes ATCC19114, using combined staining with propidium iodide (PI) for membrane damage evaluation and carboxyfluorescein diacetate (cFDA) for esterase activity detection. The antimicrobial activity of the essential oils was also tested at different NaCl concentrations.Significant differences were observed between plate count results

Antonello Paparella; Lorenzo Taccogna; Irene Aguzzi; Clemencia Chaves-López; Annalisa Serio; Fulvio Marsilio; Giovanna Suzzi

2008-01-01

326

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

Microsoft Academic Search

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

Zhang Xueqing; Wei Yi; Xu Shenchu; Zhang Yu

2010-01-01

327

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

328

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

NASA Astrophysics Data System (ADS)

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

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

2014-02-01

329

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

NASA Technical Reports Server (NTRS)

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

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

2013-01-01

330

Variational energy principle for compressible, baroclinic flow. 1: First and second variations of total kinetic action  

NASA Technical Reports Server (NTRS)

The case of a cold gas in the absence of external force fields is considered. Since the only energy involved is kinetic energy, the total kinetic action (i.e., the space-time integral of the kinetic energy density) should serve as the total free-energy functional in this case, and as such should be a local minimum for all possible fluctuations about stable flow. This conjecture is tested by calculating explicit, manifestly covariant expressions for the first and second variations of the total kinetic action in the context of Lagrangian kinematics. The general question of the correlation between physical stability and the convexity of any action integral that can be interpreted as the total free-energy functional of the flow is discussed and illustrated for the cases of rectillinear and rotating shearing flows.

Schmid, L. A.

1977-01-01

331

Mass, momentum and energy flow from an MPD accelerator. Ph.D. Thesis  

NASA Technical Reports Server (NTRS)

The mass, momentum, and energy flows are measured over a current range of 8 to 50 kA and inlet mass flows of 2 to 36q/sec of argon. The momentum flux profile indicates that the accelerator produces a uniform, 2-inch diameter axial jet at the anode which expands into a Gaussian profile at an axial station 11 inches from the anode. The electromagnetic component of the thrust is found to follow the familiar quadratic dependence on arc current, while a more complex empirical relation is needed to correlate the gasdynamic contribution with the current and mass flow rate. Using available time-of-flight velocity profiles at a current of 16 kA and a mass flow of 5.9 g/sec, calculated flux profiles of mass and kinetic energy exhibit a tendency for some fraction of the inlet mass flow to leak out at a low velocity around the central high velocity core.

Cory, J. S.

1971-01-01

332

Structure of turbulent flow in EMEC's tidal energy test site  

Microsoft Academic Search

Measurements of bulk turbulent parameters (Kinetic energy, dissipation rates, Reynolds stress, etc.) were performed in the bottom boundary layer of the European Marine Energy Centre (EMEC) tidal test site using Acoustic Doppler Current Profilers (ADCPs). Flood and ebb currents exceed 1.4 ms?1 near the seabed (at 2.63 mab) and generate >7 Pa stresses. The production of turbulent kinetic energy (TKE) P, was found

Emmanuel Osalusi; Jonathan Side; Robert Harris

2009-01-01

333

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

NASA Technical Reports Server (NTRS)

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

Khodadoust, Abdollah; Washburn, Anthony

2007-01-01

334

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

335

Fundamental Study of Direct Contact Cold Energy Release by Flowing Hot Air through Ice Particles Packed Layer  

NASA Astrophysics Data System (ADS)

This paper has dealt with the direct contact heat exchange characteristics between ice particles (average ice particle diameter : 3.10mm) packed in the rectangular cold energy storage vessel and flowing hot air as a heat transfer medium. The hot air bubbles ascended in the fluidized ice particles layer, and they were cooled down directly by melting ice particles. The temperature efficiency increased as Reynolds number Re increased because the hot air flowing in the layer became active. The dehumidity efficiency increased with an increase in modified Stefan number and Re, since the heat capacity of inlet air and heat transfer coefficient increased. Finally, some empirical correlations for temperature efficiency, dehumidity efficiency and the completion time of cold energy release were derived in terms of various nondimensional parameters.

Aoyama, Sigeo; Inaba, Hideo

336

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

337

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

338

Energy flow analysis in vibrating systems by laser vibrometer measurements  

Microsoft Academic Search

In this paper an experimental analysis of the energy transmission in vibrating structures is considered. The classical discretization techniques (FEM, BEM) fail when one tries to solve high-frequency dynamic problems. At present, SEA is the most acknowledged theory for providing such kind of solution, giving information on the stored mechanical energy and on the dissipated mechanical power between the modal

Antonio Culla; Aldo Sestieri

2002-01-01

339

Co-laminar flow cells for electrochemical energy conversion  

NASA Astrophysics Data System (ADS)

In this review, we present the major developments in the evolution of ‘membraneless’ microfluidic electrochemical cells which utilize co-laminar flow to minimize reactant mixing while producing electrical power in a compact form. Categorization of devices according to reactant phases is suggested, with further differentiation being subject to fabrication method and function, namely multi-layer sandwich structures for medium-power cell stacks and single-layer monolithic cells for low-power on-chip applications. Power density metrics reveal that recent co-laminar flow cells compare favourably with conventional membrane-based electrochemical cells and that further optimization of device architecture could be expedited through standardized testing. Current research trends indicate that co-laminar flow cell technology for power generation is growing rapidly and finding additional use as an analytical and education tool. Practical directions and recommendations for further research are provided, with the intention to guide scientific advances and technology development toward ultimate pairing with commercial applications.

Goulet, Marc-Antoni; Kjeang, Erik

340

Fluid flow and heat convection studies for actively cooled airframes  

NASA Astrophysics Data System (ADS)

This report details progress made on the jet impingement - liquid crystal - digital imaging experiment. With the design phase complete, the experiment is currently in the construction phase. In order to reach this phase two design related issues were resolved. The first issue was to determine NASP leading edge active cooling design parameters. Meetings were arranged with personnel at SAIC International, Torrance, CA in order to obtain recent publications that characterized expected leading edge heat fluxes as well as other details of NASP operating conditions. The information in these publications was used to estimate minimum and maximum jet Reynolds numbers needed to accomplish the required leading edge cooling, and to determine the parameters of the experiment. The details of this analysis are shown in Appendix A. One of the concerns for the NASP design is that of thermal stress due to large surface temperature gradients. Using a series of circular jets to cool the leading edge will cause a non-uniform temperature distribution and potentially large thermal stresses. Therefore it was decided to explore the feasibility of using a slot jet to cool the leading edge. The literature contains many investigations into circular jet heat transfer but few investigations of slot jet heat transfer. The first experiments will be done on circular jets impinging on a fiat plate and results compared to previously published data to establish the accuracy of the method. Subsequent experiments will be slot jets impinging on full scale models of the NASP leading edge. Table 1 shows the range of parameters to be explored. Next a preliminary design of the experiment was done. Previous papers which used a similar experimental technique were studied and elements of those experiments adapted to the jet impingement study. Trade-off studies were conducted to determine which design was the least expensive, easy to construct, and easy to use. Once the final design was settled, vendors were contacted to verify that equipment could be obtained to meet our specifications. Much of the equipment required to complete the construction of the experiment has been ordered or received.

Mills, A. F.

341

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

342

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

NASA Technical Reports Server (NTRS)

An exact conservation equation is derived which generalizes the familiar acoustic energy equations. The new relation is valid for arbitrary disturbances to a viscous, compressible flow. It is suggested by a development of the acoustic energy equation by means of a regular perturbation expansion of the general energy equation of fluid mechanics. A perturbation energy density and flux are defined and identified as the exact physical quantities whose leading order perturbation representations are the usual acoustic energy density and flux. The conservation equation governing the perturbation energy quantities is shown to yield previously known results for several special cases.

Myers, M. K.

1986-01-01

343

Active control of panel vibrations induced by boundary-layer flow  

NASA Technical Reports Server (NTRS)

Some problems in active control of panel vibration excited by a boundary layer flow over a flat plate are studied. In the first phase of the study, the optimal control problem of vibrating elastic panel induced by a fluid dynamical loading was studied. For a simply supported rectangular plate, the vibration control problem can be analyzed by a modal analysis. The control objective is to minimize the total cost functional, which is the sum of a vibrational energy and the control cost. By means of the modal expansion, the dynamical equation for the plate and the cost functional are reduced to a system of ordinary differential equations and the cost functions for the modes. For the linear elastic plate, the modes become uncoupled. The control of each modal amplitude reduces to the so-called linear regulator problem in control theory. Such problems can then be solved by the method of adjoint state. The optimality system of equations was solved numerically by a shooting method. The results are summarized.

Chow, Pao-Liu

1991-01-01

344

SEQUENTIAL NITRIFICATION-DENITRIFICATION IN A PLUG FLOW ACTIVATED SLUDGE SYSTEM  

EPA Science Inventory

The use of the carbon sources present in municipal wastewater to provide the energy required for nitrification-denitrification was evaluated on a pilot plant scale in a simulated plug flow reactor. Most of this report is devoted to the results from operation of a nine-pass activa...

345

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

346

Energy flow analysis and design sensitivity of structural problems at high frequencies  

Microsoft Academic Search

The design sensitivity formulation of an energy finite element method is presented using the direct differentiation and adjoint variable methods. The continuum method is used to derive the design sensitivity equation of the energy flow equation, whereas the discrete method is used to calculate the variation of the coupling relation. For design variables, material property, panel thickness, and structural shape

Nam Ho Kim; Jun Dong; Kyung Kook Choi

2004-01-01

347

NETWORK ANALYSIS OF THE ENERGY FLOW THROUGH THE DUBLIN BAY ECOSYSTEM  

Microsoft Academic Search

Energy (biomass) and energy flows (production, inputs, transfers and respiration) were calculated for seven compartments (phytoplankton, benthic primary producers, zooplankton, benthic macro- fauna, fish, birds and particulate organic matter (POM)) of the Dublin Bay system. The resultant model was analysed with the SCOR network analysis package. The most prominent feature of the model was the importance of the allochthonous input

James G. Wilson; Andrew Parkes

1998-01-01

348

Energy flow through an Apatani village ecosystem of Arunachal Pradesh in northeast India  

Microsoft Academic Search

The energy flow through the ecosystem of a typical Apatani village in Arunachal Pradesh in northeastern India was studied. The energy and economic efficiency of the rice agro-ecosystem of this region is exceptionally high, and rice is exported after meeting local needs. The cropping pattern varies depending upon the amount of organic residues recycled into the system. Where recycling is

Anil Kumar I; P. S. Ramakrishnan

1990-01-01

349

Energy flow model of an oxygen-deficient estuary on the Swedish west coast  

Microsoft Academic Search

The estuary Byfjord (Sweden) is characterized by high primary production, a well developed meiofauna compared to the macrofauna, high epifaunal biomass, a low number of herbivorous copepods and a small fish stock. A simplified energy flow model of the ecosystem of the fjord is given. The energy transfer is approximated to 15%. About one-fourth-300 (metric) tons of carbon — of

R. Rosenberg; I. Olsson; E. Ölundh

1977-01-01

350

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

NASA Astrophysics Data System (ADS)

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

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

1992-09-01

351

A Helioseismic Survey to Investigate Relationships between Subsurface Flows beneath Large Active Regions and Solar Flares  

NASA Astrophysics Data System (ADS)

A survey of the subsurface flow properties of about 120 of the largest active regions, determined from the application of helioseismic holography to Dopplergrams obtained with the HMI instrument onboard the Solar Dynamics Observatory, is being carried out. The overriding goal is to characterize differences in the subsurface flows between active regions associated with eruptive flares and the flows observed in relatively quiescent regions. Applications to flare forecasting comprise only one part of this investigation, since the potential response of the subsurface environment to eruptive events during and after their occurrence is also of scientific interest. Other priorities include understanding the limitations of the helioseismic methods, identifying and correcting systematic effects, and validating the reliability of the measurements using artificial data. While inversions to determine the variation with depth of subsurface flows are planned, preliminary results will be discussed which make use of proxies for near-surface depth-integrated properties, including the horizontal component of the flow divergence and the vertical component of the flow vorticity.This work is supported by the Solar Terrestrial Program of the National Science Foundation, through grant AGS-1127327, and by the National Oceanic and Atmospheric Administration SBIR program.

Braun, Douglas; Leka, K D.; Barnes, Graham

2014-06-01

352

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

353

Effects of surface active elements on weld pool fluid flow and weld penetration in gas metal arc welding  

NASA Astrophysics Data System (ADS)

This article presents a mathematical model simulating the effects of surface tension (Maragoni effect) on weld pool fluid flow and weld penetration in spot gas metal arc welding (GMAW). Filler droplets driven by gravity, electromagnetic force, and plasma arc drag force, carrying mass, thermal energy, and momentum, periodically impinge onto the weld pool. Complicated fluid flow in the weld pool is influenced by the droplet impinging momentum, electromagnetic force, and natural convection due to temperature and concentration gradients, and by surface tension, which is a function of both temperature and concentration of a surface active element (sulfur in the present study). Although the droplet impinging momentum creates a complex fluid flow near the weld pool surface, the momentum is damped out by an “up-and-down” fluid motion. A numerical study has shown that, depending upon the droplet’s sulfur content, which is different from that in the base metal, an inward or outward surface flow of the weld pool may be created, leading to deep or shallow weld penetration. In other words, it is primarily the Marangoni effect that contributes to weld penetration in spot GMAW.

Wang, Y.; Tsai, H. L.

2001-06-01

354

Early VEGFR2 activation in response to flow is VEGF-dependent and mediated by MMP activity  

PubMed Central

Although several potential mechanosensors/mechanotransducers have been proposed, the precise mechanisms by which ECs sense and respond to mechanical forces and translate them into biochemical signals remains unclear. Here, we report that two major ligand-dependent tyrosine autophosphorylation sites of VEGFR2, Y1175 and Y1214, are rapidly activated by shear stress in human coronary artery endothelial cells (HCAECs). Neutralizing antibody against VEGFR2 not only abrogates flow-induced phosphorylation of these tyrosine residues, but also has a marked inhibitory effect on downstream eNOS activation. In situ proximity ligation assay revealed that VEGF and VEGFR2 are closely associated in HCAECs, and more importantly, this association is increased with flow. Finally, we show that flow-induced VEGFR2 activation is attenuated in the presence of the broad spectrum matrix metalloproteinase (MMP) inhibitor, GM6001. Taken together, our results suggest that a ligand-dependent mechanism involving the activity of MMPs plays a key role in the early, shear stress-induced activation of VEGFR2.

dela Paz, Nathaniel G.; Melchior, Benoit; Frangos, John A.

2014-01-01

355

Grain size reduction in granular flows of spheres - The effects of critical impact energy  

NASA Technical Reports Server (NTRS)

Methods employed to derive recent kinetic theories for rapid noncomminuting granular flows are extended to homogeneous flows in which a fraction of the repeated collisions produce tiny fractures on the particles' peripheries and gradually reduce their effective diameters. The theory consists of balance equations for mass, momentum, and energy, as well as constitutive relations for the presence tensor and collisional rates of mass and energy lost. The work of Richman and Chou (1989) is improved by incorporating into the constitutive theory the critical impact energy below which no mass loss occurs in a binary collision. The theory is applied to granular shear flows and, for fixed shear rates, predicts the time variations of the solid fraction granular temperature, and induced stresses, as well as their extreme sensitivities to small changes in the critical impact energy.

Richman, M. W.; Oyediran, A. A.

1992-01-01

356

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

NASA Astrophysics Data System (ADS)

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

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

1990-06-01

357

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

NASA Technical Reports Server (NTRS)

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

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

1990-01-01

358

A flow microcalorimeter system for the measurement of dynamic energy variables of isolated perfused hearts.  

PubMed

An isothermic flow microcalorimeter system for fluid rates of 1-50 cm3 min -1 has been developed to measure the total heat flow produced by isolated perfused small animal hearts and its rate of change. The heat, which is absorbed by the perfusion fluid flowing through the coronary capillary system, is detected by passing the coronary effluent through a plate heat exchanger mounted in intimate contact with the internal surface of a gradient layer calorimeter. By employing electrical calibration, this heat flow detector gives a precision of +/- 0.2 m W for average effluent rates of about 15 cm3 min-1. The method provides direct comparison of the biologically produced heat flow with electrically generated energy flows. The response time to step changes in heat flow is 1 min to 90% of the total change. Possible systematic errors are analysed and quantified, using a heart bypass flow technique and a thermoelectric differential temperature meter. The accuracy of the measurement of constant heat sources with the complete system over the range of 5-40 mW is +/- 2% for fluid rates up to 40 cm3 min-1. Measurements with small rat hearts have given absolute values between 17 and 36 mW measured with an accuracy of +/- 3%. The rate of total myocardial energy turnover can be studied with the system. PMID:7323146

Niesler, R A; Axon, D W

1981-11-01

359

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

360

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

SciTech Connect

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

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

2013-09-20

361

Aircraft energy efficiency laminar flow control wing design study  

NASA Technical Reports Server (NTRS)

An engineering design study was performed in which laminar flow control (LFC) was integrated into the wing of a commercial passenger transport aircraft. A baseline aircraft configuration was selected and the wing geometry was defined. The LFC system, with suction slots, ducting, and suction pumps was integrated with the wing structure. The use of standard aluminum technology and advanced superplastic formed diffusion bonded titanium technology was evaluated. The results of the design study show that the LFC system can be integrated with the wing structure to provide a structurally and aerodynamically efficient wing for a commercial transport aircraft.

Bonner, T. F., Jr.; Pride, J. D., Jr.; Fernald, W. W.

1977-01-01

362

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

363

Searching for Large-scale flows around Active Regions with Hinode  

NASA Astrophysics Data System (ADS)

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

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

2008-05-01

364

Improved Algorithm for Gradient Vector Flow Based Active Contour Model Using Global and Local Information  

PubMed Central

Active contour models are used to extract object boundary from digital image, but there is poor convergence for the targets with deep concavities. We proposed an improved approach based on existing gradient vector flow methods. Main contributions of this paper are a new algorithm to determine the false part of active contour with higher accuracy from the global force of gradient vector flow and a new algorithm to update the external force field together with the local information of magnetostatic force. Our method has a semidynamic external force field, which is adjusted only when the false active contour exists. Thus, active contours have more chances to approximate the complex boundary, while the computational cost is limited effectively. The new algorithm is tested on irregular shapes and then on real images such as MRI and ultrasound medical data. Experimental results illustrate the efficiency of our method, and the computational complexity is also analyzed.

Chen, Bingyu; Sun, Mingui; Jia, Wenyan; Yuan, Zhiyong

2013-01-01

365

Energy Conservation Teaching Activities for Home Economics Classrooms.  

ERIC Educational Resources Information Center

This collection of home economics activities is intended to meet the special needs of home economics teachers who wish to include energy education activities in their curricula. The 45 activities can be used as presented, or can be modified to individual needs or local conditions. Each activity includes: (1) title, (2) objective, (3) activity

Jedlicka, Ella, Ed.

366

Hemodynamic energy delivery of the pulsatile flow in a simulated pediatric extracorporeal circuit.  

PubMed

Objectives of this study were 1) to precisely measure the generation and delivery of hemodynamic energy levels during pediatric cardiopulmonary bypass procedure using a simulated circuit and 2) to quantify energy losses of the extracorporeal circuit components. A conventional roller pump, pediatric hollow-fiber membrane oxygenator, arterial filter, arterial cannula, and (1/4)-in tubing were used. The circuit was primed with 40/60 glycerin/water mixture. Postcannula (pseudo patient's pressure) pressure was maintained 40 mm Hg by a Hoffman clamp. All trials were conducted at 800 mL/min of pump flow with pulsatile (n=6) and nonpulsatile (n=6) modes at room temperature. Simultaneous blood flow and pressures at pre/post oxygenator and pre/post cannula sites were recorded. There were gradual decreases in values of circuit mean pressure, energy equivalent pressure, surplus hemodynamic energy, and total hemodynamic energy (THE) from pre- and postoxygenator to pre- and postcannula sites. Approximately 30% of THE generated by roller pump was damped by the membrane oxygenator. About 25% of THE was lost by the arterial filter and the length of the arterial tubing. Only 15%-18% of THE was delivered into the pseudo patient. Although the results of this study showed that the roller pump could provide higher hemodynamic energy per second with pulsatile flow compared with the nonpulsatile flow, the majority (80%) of hemodynamic energy was damped by the components of the extracorporeal circuit. PMID:19092666

Wang, Shigang; Haines, Nikkole; Undar, Akif

2009-01-01

367

Solar energy education: Renewable energy activities for chemistry and physics  

NASA Astrophysics Data System (ADS)

Information on renewable energy sources is provided for students in this teachers' guide. With the chemistry and physics student in mind, solar energy topics such as absorber plate coatings for solar collectors and energy collection and storage methods are studied.

368

Energy and materials flows in the copper industry  

SciTech Connect

The copper industry comprises both the primary copper industry, which produces 99.9%-pure copper from copper ore, and the secondary copper industry, which salvages and recycles copper-containing scrap metal to extract pure copper or copper alloys. The United States uses about 2 million tons of copper annually, 60% of it for electrical applications. Demand is expected to increase less than 4% annually for the next 20 years. The primary copper industry is concentrated in the Southwest; Arizona produced 66% of the 1979 total ore output. Primary production uses about 170 x 10/sup 12/ Btu total energy annually (about 100 x 10/sup 6/ Btu/ton pure copper produced from ore). Mining and milling use about 60% of the total consumption, because low-grade ore (0.6% copper) is now being mined. Most copper is extracted by smelting sulfide ores, with concomitant production of sulfur dioxide. Clean air regulations will require smelters to reduce sulfur emissions, necessitating smelting process modifications that could also save 20 x 10/sup 12/ Btu (10 x 10/sup 6/ Btu/ton of copper) in smelting energy. Energy use in secondary copper production averages 20 x 10/sup 6/ Btu/ton of copper. If all copper products were recycled, instead of the 30% now salvaged, the energy conservation potential would be about one-half the total energy consumption of the primary copper industry.

Gaines, L.L.

1980-12-01

369

Measuring turbulence energy with PIV in a backward-facing step flow  

Microsoft Academic Search

Turbulence energy is estimated in a backward-facing step flow with three-component (3C, stereo) particle image velocimetry (PIV). Estimates of turbulence energy transport equation for convection, turbulence transport, turbulence production, viscous diffusion, and viscous dissipation in addition to Reynolds stresses are computed directly from PIV data. Almost all the turbulence energy terms in the backward-facing step case can be measured with

M. Piirto; P. Saarenrinne; H. Eloranta; R. Karvinen

2003-01-01

370

DEVELOPMENT OF A LOW-COST INFERENTIAL NATURAL GAS ENERGY FLOW RATE PROTOTYPE RETROFIT MODULE  

Microsoft Academic Search

In 1998, Southwest Research Institute{reg_sign} began a multi-year project co-funded by the Gas Research Institute (GRI) and the U.S. Department of Energy. The project goal is to develop a working prototype instrument module for natural gas energy measurement. The module will be used to retrofit a natural gas custody transfer flow meter for energy measurement, at a cost an order

E. Kelner; T. E. Owen; D. L. George; A. Minachi; M. G. Nored; C. J. Schwartz

2004-01-01

371

Active Feedback Control of a Web Flutter Using Flow Control Devices  

Microsoft Academic Search

This paper develops a non-contact active feedback control of web flutter in a narrow passage by using movable plates set at inlet and outlet of the passage. The strategy of this active feedback control is based on the flow-control which cancels the exciting fluid force acting on the web, i.e., cancels the self-excited feedback mechanism. In this paper, suppression of

Yusuke Hayashi; Masahiro Watanabe; Kensuke Hara

2010-01-01

372

Investigation of triclosan fate and toxicity in continuous-flow activated sludge systems  

Microsoft Academic Search

The purpose of this research was to study the fate and toxicity of triclosan (TCS) in activated sludge systems and to investigate the role of biodegradation and sorption on its removal. Two continuous-flow activated sludge systems were used; one system was used as a control, while the other received TCS concentrations equal to 0.5 and 2mgl?1. At the end of

Athanasios S. Stasinakis; Anastasios V. Petalas; Daniel Mamais; Nikolaos S. Thomaidis; Georgia Gatidou; Themistokles D. Lekkas

2007-01-01

373

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.

374

Energy Conservation Activity Packet, Grade 6. Revised Edition.  

ERIC Educational Resources Information Center

This activity notebook for grade 6 is one of 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 six. The packet is divided into two parts and provides the teacher with background information, concepts and…

Pohlman, Betty; And Others

375

Robust Segmentation of Freehand Ultrasound Image Slices Using Gradient Vector Flow Fast Geometric Active Contours  

Microsoft Academic Search

We propose a new semi-automatic segmentation strategy on echocardiographic images, which combines a recently introduced gradient vector flow (GVF) fast geometric active contour (GAC) model and a modified level sets methods applied to echocardiographic data by Corsi et al.. We call it adaptive GVF GAC model. We note that echocardiographic images are characterized by high levels of speckle noise, weakly-defined

Honggang Yu; M. S. Pattichism; M. Beth Goens

2006-01-01

376

Switching Resilient PI Controllers for Active Queue Management of TCP Flows  

Microsoft Academic Search

Active Queue Management (AQM) is used in computer networks to increase link utilization with less queueing delays. The fluid flow model of TCP based on delay differential equations supplies the mathematical background for modelling the AQM as a feedback system. Recently various PI and PID controllers are designed for this feedback system, [7], [18]. In this paper, we consider the

Deniz Üstebay; Hitay Özbay

2007-01-01

377

Bandwidth allocation for non-responsive flows with active queue management  

Microsoft Academic Search

This paper addresses the problem of configuring active queue management systems (e.g. WRED and RIO) for service level specifications in internetworks. In particular, we focus on assured forwarding (AF) for non-responsive flows in differentiated services networks. The difficulty is to determine the correct queue level thresholds that will result in correct drop rates for various AF precedence levels under any

Ed Bowen; Clark Jeffries; Lukas Kencl; Andreas Kind; Roman Pletka

2002-01-01

378

Enabling Active Flow Manipulation in Silicon-Based Network Forwarding Engines  

Microsoft Academic Search

A significant challenge in today's Internet is the a bility to efficiently incorporate c ustomizable network intelligences in commercial high p erformance network devices. This paper tackles the c hallenge by introducing the Active Flow Manipulation (AFM) mechanism, a key enabling technology of the programmable networking platform Openet. AFM enhances the c ontrol i ntelligence of network devices through programmability.

Tal Lavian; Phil Wang; Franco Travostino; Siva Subramanian; Ramesh Durairaj; Doan B. Hoang; Vijak Sethaput; David E. Culler

2002-01-01

379

A review of the impact and potential of intermittent aeration on continuous flow nitrifying activated sludge  

Microsoft Academic Search

Intermittent aeration of activated sludge plants (ASPs) is a potential strategy that may help deliver reduced operational costs while providing an adequate effluent quality. This review paper critically assesses the implications of temporary turning aeration off in continuous flow nitrifying ASPs, including impact on dissolved oxygen concentrations, process biology and operational parameters. The potential savings and pitfalls of the approach

Gabriela Dotro; Bruce Jefferson; Mark Jones; Peter Vale; Elise Cartmell; Tom Stephenson

2011-01-01

380

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

381

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

382

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

ERIC Educational Resources Information Center

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

Roelofs, Ardi; Dijkstra, Ton; Gerakaki, Svetlana

2013-01-01

383

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

Microsoft Academic Search

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

ELENA NEAGU; VERONICA MOROEANU; GABRIEL LUCIAN RADU

2008-01-01

384

Transformation from Data Flow Diagram to UML2.0 activity diagram  

Microsoft Academic Search

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

Fanchao Meng; Dianhui Chu; Dechen Zhan

2010-01-01

385

Active Control of Panel Vibrations Induced by Boundary-Layer Flow.  

National Technical Information Service (NTIS)

Some problems in active control of panel vibration excited by a boundary layer flow over a flat plate are studied. In the first phase of the study, the optimal control problem of vibrating elastic panel induced by a fluid dynamical loading was studied. Fo...

P. Chow

1991-01-01

386

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

EPA Science Inventory

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

387

Relationship between sealing ability of Activ GP and Gutta Flow and methods of calcium hydroxide removal  

PubMed Central

Aim: To evaluate the effect of method of calcium hydroxide intracanal dressing removal, on sealing ability of Gutta Flow and Activ GP. Materials and Methods: Seventy extracted mandibular premolars were sectioned at CEJ and canals were prepared with profile 4% rotary file till #40. Canals were filled with calcium hydroxide, coronally sealed with Cavit G and stored at 37°C. After 7 days, samples were divided on the basis of calcium hydroxide removal method (Master apical file, Navi Tip FX, and F File) and obturating material (Activ GP and Gutta Flow). Three coats of nail polish were applied except 2 mm around apical foramen and samples were immersed in India ink dye, sectioned, and observed under stereomicroscope for microleakage. Results: The results were statistically analyzed with one way ANOVA-F with Tukey HSD test with the null hypothesis set as 5%. Conclusions: The seal of the canal system was adversely impacted by residual calcium hydroxide when Activ GP and Gutta Flow were used as obturating material and the sealing ability of Activ GP and Gutta Flow was better when MAF was used for removal of calcium hydroxide than F file or Navi tip FX.

Nikhil, Vineeta; Singh, Vijay; Singh, Simranjeet

2012-01-01

388

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

PubMed

Equilibrium statistical mechanics tools have been developed to obtain indications about the natural tendencies of nonlinear energy transfers in two-dimensional and quasi-two-dimensional flows like rotating and stratified flows in geostrophic balance. In this article we consider a simple model of such flows with a nontrivial vertical structure, namely, two-layer quasigeostrophic flows, which remain amenable to analytical study. We obtain the statistical equilibria of the system in the case of a linear vorticity-stream function relation, build the corresponding phase diagram, and discuss the most probable outcome of nonlinear energy transfers, both on the horizontal and on the vertical, in the presence of stratification and rotation. PMID:24730938

Herbert, Corentin

2014-03-01

389

Energy information activities at the FEA  

Microsoft Academic Search

The Federal Energy Administration (FEA) is responsible for the development, publication, and dissemination of energy information. This information is prepared to support three primary missions. First, extensive, accurate data are needed to implement FEA programs, particularly regulatory operations. Second, reliable energy information is needed to develop and evaluate Federal energy policy. Third, FEA has a legislative mandate to publish statistical

1976-01-01

390

Methane source strength and energy flow shape methanotrophic communities in oxygen-methane counter-gradients.  

PubMed

The role of microbial diversity for ecosystem functioning has become an important subject in microbial ecology. Recent work indicates that microbial communities and microbial processes can be very sensitive to anthropogenic disturbances. However, to what extent microbial communities may change upon, resist to, or overcome disturbances might differ depending on substrate availability. We used soil from an Italian rice field in gradient microcosms, and analysed the response of methanotrophic communities to an NH4 (+) pulse as a potential disturbance under two different CH4 source strengths. We found a significant influence of source strength, i.e. the energy flow through the methanotrophic community, while NH4 (+) had no effect. Our data suggest that historical contingencies, i.e. nitrogen fertilization, led to an ammonium-tolerant MOB community. Methanotrophs were able to oxidize virtually all CH4 diffusing into the oxic-anoxic boundary layer regardless of NH4 (+) addition. Total and active methanotrophic communities were assessed by a pmoA-specific microarray. From the reservoir of dormant methanotrophs, different species became active with Methylobacter and an environmental cluster affiliated with paddy soils being indicative for high CH4 source strength. Thus, a microbial seed bank is an important prerequisite to maintain functioning in a fluctuating environment. PMID:23757274

Krause, Sascha; Lüke, Claudia; Frenzel, Peter

2012-04-01

391

Energy deposition, heat flow, and rapid solidification during laser and electron beam irradiation of materials  

SciTech Connect

The fundamentals of energy deposition, heat flow, and rapid solidification during energy deposition from lasers and electron beams is reviewed. Emphasis is placed on the deposition of energy from pulsed sources (10 to 100 ns pulse duration time) in order to achieve high heating and cooling rates (10/sup 8/ to 10/sup 10/ /sup 0/C/s) in the near surface region. The response of both metals and semiconductors to pulsed energy deposition is considered. Guidelines are presented for the choice of energy source, wavelength, and pulse duration time.

White, C.W.; Aziz, M.J.

1985-10-01

392

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

393

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

394

A Unified Three-Phase Power-Flow Analysis Model For Electronically Coupled Distributed Energy Resources  

Microsoft Academic Search

This paper develops and presents a unified and generic three-phase, steady-state, fundamental-frequency, se- quence-frame-based model of the voltage-sourced converter (VSC) for power-flow analysis of VSC-interfaced Distributed Energy Resource (DER) units. The model is unified since it represents: 1) three-wire and four-wire VSC configurations; 2) balanced and unbalanced power-flow scenarios; 3) various VSC control strategies and options; and 4) operating limits

Mohamed Zakaria Kamh; Reza Iravani

2011-01-01

395

Energy flow and the vertical structure of real ecosystems  

Microsoft Academic Search

Three possible explanations for the well-known limitation of food chain lengths to two or three links for the most part are subjected to an empirical test, using the fact that ectotherms, especially invertebrates, tend to have higher production efficiencies than endotherms. The data are consistent with the hypothesis that food chain lengths are limited by the availability of energy.

Peter Yodzis

1984-01-01

396

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

397

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

398

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

NASA Astrophysics Data System (ADS)

Active flow control experiments were carried out over a NACA 0015 airfoil with a trailing edge flap. Two arrays of synthetic jet actuators were mounted in the airfoil with one on near the leading edge (0.1c) and the other on the main wing body near the wing/flap interface (0.65c). Characterization of the SJA's showed they produced their highest exit velocities at a frequency of 1100 Hz, which was near the natural frequency of the piezo membranes. When actuated at frequencies corresponding to the flow natural frequencies (10-100Hz) the jets produced no jet velocity. In order to control the flow using a frequency near the flow's natural shedding frequency the synthetic jets were actuated using a forcing frequency near the piezo natural frequency with a duty cycle frequency of 10-1000Hz. Force balance results showed that for a 0 flap deflection the active flow control delayed stall and lowered drag regardless of the duty cycle frequency. At flap deflections of 20 and 40 differences were observed between the continuously forced and duty cycles cases. For these cases continuous forcing increased the stall angle and reduced drag. Duty cycle forcing also delayed stall however it significantly increased drag near the stall AOA even compared to the no forcing case.

Kabiri, Pooya; Bohl, Douglas; Ahmadi, Goodarz

2011-11-01

399

78 FR 64414 - Assistance to Foreign Atomic Energy Activities  

Federal Register 2010, 2011, 2012, 2013

...Katie Strangis, National Nuclear Security Administration...Assistance to Foreign Atomic Energy Activities since 1986...current global civil nuclear trade practices and nonproliferation...subject to the Secretary of Energy's specific authorization...judicial or evidentiary-type hearing. Any...

2013-10-29

400

Workshop Report on Quantifying Environmental Damage from Energy Activities.  

National Technical Information Service (NTIS)

Data and methods for quantifying environmental damage from energy activities were evaluated. Specifically, discussions were designed to identify the types and amounts of pollutants emitted by energy technologies that may affect the environment adversely, ...

P. D. Moskowitz M. D. Rowe S. C. Morris L. D. Hamilton

1977-01-01

401

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

402

Active control of panel vibrations induced by a boundary layer flow  

NASA Technical Reports Server (NTRS)

The problems of active and passive control of sound and vibration has been investigated by many researchers for a number of years. However, few of the articles are concerned with the sound and vibration with flow-structure interaction. Experimental and numerical studies on the coupling between panel vibration and acoustic radiation due to flow excitation have been done by Maestrello and his associates at NASA/Langley Research Center. Since the coupled system of nonlinear partial differential equations is formidable, an analytical solution to the full problem seems impossible. For this reason, we have to simplify the problem to that of the nonlinear panel vibration induced by a uniform flow or a boundary-layer flow with a given wall pressure distribution. Based on this simplified model, we have been able to consider the control and stabilization of the nonlinear panel vibration, which have not been treated satisfactorily by other authors. Although the sound radiation has not been included, the vibration suppression will clearly reduce the sound radiation power from the panel. The major research findings are presented in three sections. In section two we describe results on the boundary control of nonlinear panel vibration, with or without flow excitation. Sections three and four are concerned with some analytical and numerical results in the optimal control of the linear and nonlinear panel vibrations, respectively, excited by the flow pressure fluctuations. Finally, in section five, we draw some conclusions from research findings.

Chow, Pao-Liu

1995-01-01

403

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

404

Transferring the concept of minimum energy expenditure from river networks to subsurface flow patterns  

NASA Astrophysics Data System (ADS)

Principles of optimality provide an interesting alternative to modeling hydrological processes in detail on small scales. However, the concepts still seem to be on a visionary level except for the theory of minimum energy expenditure for river networks. Inspired by this approach, we present a theory of minimum energy expenditure in subsurface flow in order to obtain a better understanding of preferential flow patterns in the subsurface. The concept describes flow patterns which are optimal in the sense that they minimize the total energy expenditure at given recharge under the side condition of a given total porosity. Results are illustrated using two examples: two-dimensional flow towards a spring with a radial symmetric distribution of the porosity and dendritic flow patterns. The latter are found to be similar to river networks in their structure and, as a main result, the model predicts a power-law distribution of the spring discharges. In combination with two data sets from the Austrian Alps, this result is used for validating the model. Both data sets reveal power-law distributed spring discharges with similar scaling exponents. These are, however, slightly larger than the exponent predicted by the model. As a further result, the distributions of the residence times strongly differ between homogeneous porous media and optimized flow patterns, while the mean residence times seem to be similar in both cases.

Hergarten, S.; Winker, G.; Birk, S.

2014-06-01

405

Daily Activity Energy Expenditure and Mortality Among Older Adults  

Microsoft Academic Search

Context Exercise is associated with mortality benefits but simply expending energy through any activity in an individual's free-living environment may confer survival ad- vantages. Objective To determine whether free-living activity energy expenditure is associ- ated with all-cause mortality among older adults. Design, Setting, and Participants Free-living activity energy expenditure was assessed in 302 high-functioning, community-dwelling older adults (aged 70-82 years).

Todd M. Manini; James E. Everhart; Kushang V. Patel; Dale A. Schoeller; Lisa H. Colbert; Marjolein Visser; Frances Tylavsky; Douglas C. Bauer; Bret H. Goodpaster; Tamara B. Harris

2007-01-01

406

Numerical simulation of material and energy flow in an e-beam melt furnace  

SciTech Connect

A numerical analysis is made of the material and energy flow in an electron-beam furnace. Energy from an electron beam vaporizes metal confined in a water-cooled crucible. At the beam impact site a. recirculating liquid metal pool is surrounded by a shell of its own solid. A Galerkin finite element method is modified to solve for the flow and temperature fields along with interface locations. The deforming mesh is parameterized using spines that pivot and stretch as the interfaces move. Results are given for an aluminum vaporizer in which parametric variations are made in the e-beam power and liquid viscosity. The calculations reveal the importance of the coupling between the free boundaries and the flow and energy fields.

Westerberg, K.W.; McClelland, M.A. [Lawrence Livermore National Lab., CA (United States); Finlayson, B.A. [Washington Univ., Seattle, WA (United States). Dept. of Chemical Engineering

1993-12-01

407

Effect of acute hypoxia on regional cerebral blood flow: effect of sympathetic nerve activity.  

PubMed

We examined 1) whether global cerebral blood flow (CBF) would increase across a 6-h bout of normobaric poikilocapnic hypoxia and be mediated by a larger increase in blood flow in the vertebral artery (VA) than in the internal carotid artery (ICA); and 2) whether additional increases in global CBF would be evident following an ?1-adrenergic blockade via further dilation of the ICA and VA. In 11 young normotensive individuals, ultrasound measures of ICA and VA flow were obtained in normoxia (baseline) and following 60, 210, and 330 min of hypoxia (FiO2 = 0.11). Ninety minutes prior to final assessment, participants received an ?1-adrenoreceptor blocker (prazosin, 1 mg/20 kg body mass) or placebo. Compared with baseline, following 60, 220, and 330 min of hypoxia, global CBF [(ICAFlow + VAFlow) ? 2] increased by 160 ± 52 ml/min (+28%; P = 0.05), 134 ± 23 ml/min (+23%; P = 0.02), and 113 ± 51 (+19%; P = 0.27), respectively. Compared with baseline, ICAFlow increased by 23% following 60 min of hypoxia (P = 0.06), after which it progressively declined. The percentage increase in VA flow was consistently larger than ICA flow during hypoxia by ?20% (P = 0.002). Compared with baseline, ICA and VA diameters increased during hypoxia by ?9% and ?12%, respectively (P ? 0.05), and were correlated with reductions in SaO2. Flow and diameters were unaltered following ?1 blockade (P ? 0.10). In conclusion, elevations in global CBF during acute hypoxia are partly mediated via greater increases in VA flow compared with ICA flow; this regional difference was unaltered following ?1 blockade, indicating that a heightened sympathetic nerve activity with hypoxia does not constrain further dilation of larger extracranial blood vessels. PMID:24610534

Lewis, Nia C S; Messinger, Laura; Monteleone, Brad; Ainslie, Philip N

2014-05-01

408

Active Control of Flow around NACA 0015 Airfoil by Using DBD Plasma Actuator  

NASA Astrophysics Data System (ADS)

In this study, effect of plasma actuator on a flat plate and manipulation of flow separation on NACA0015 airfoil with plasma actuator at low Reynolds numbers were experimentally investigated. In the first section of the study, plasma actuator which consists of positive and grounded electrode couple and dielectric layer, located on a flat plate was actuated at different frequencies and peak to peak voltages in range of 3-5 kHz and 6-12 kV respectively. Theinduced air flow velocity on the surface of flat plate was measured by pitot tube at different locations behind the actuator. The influence of dielectricthickness and unsteady actuation with duty cycle was also examined. In the second section, the effect of plasma actuator on NACA0015 airfoil was studied atReynolds number 15000 and 30000. Four plasma actuators were placed at x/C = 0.1, 0.3, 0.5 and 0.9, and different electrode combinations were activated by sinusoidal signal. Flow visualizations were done when the attack angles were 0°, 5°, 10°, 15° and 20°. The results indicate that up to the 15° attack angle, the separated flow was reattached by plasma actuator at 12kV peak to peak voltage and 4 kHz frequency. However, 12 kVpp voltage was insufficient to reattach the flow at 20° angle of attack. The separated flow could be reattached by increasing the voltage up to 13 kV. Lift coefficient was also increased by the manipulated flow over the airfoil. Results showed that even high attack angles, the actuators can control the flow separation and prevent the airfoil from stall at low Reynolds numbers.

Akansu, Y. E.; Karakaya, F.; ?anl?soy, A.

2013-04-01

409

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

410

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

411

A model of localised Rac1 activation in endothelial cells due to fluid flow.  

PubMed

Endothelial cells respond to fluid flow by elongating in the direction of flow. Cytoskeletal changes and activation of signalling molecules have been extensively studied in this response, including: activation of receptors by mechano-transduction, actin filament alignment in the direction of flow, changes to cell-substratum adhesions, actin-driven lamellipodium extension, and localised activation of Rho GTPases. To study this process we model the force over a single cell and couple this to a model of the Rho GTPases, Rac and Rho, via a Kelvin-body model of mechano-transduction. It is demonstrated that a mechano-transducer can respond to the normal component of the force is likely to be a necessary component of the signalling network in order to establish polarity. Furthermore, the rate-limiting step of Rac1 activation is predicted to be conversion of Rac-GDP to Rac-GTP, rather than activation of upstream components. Modelling illustrates that the aligned endothelial cell morphology could attenuate the signalling network. PMID:21439300

Allen, R J; Bogle, I D L; Ridley, A J

2011-07-01

412

Free energy and entropy flows in magnetised plasma turbulence  

NASA Astrophysics Data System (ADS)

Just as fluid turbulence can be conceptualised as a cascade of kinetic energy from large to small scales, kinetic plasma turbulence is a cascade of free energy in the 6D phase space (position and velocity). I will discuss this as a general principle and then specialise to the case of magnetised plasma turbulence at kinetic (sub-ion-Larmor) scales. At these scales, the free energy flux arriving from the inertial range splits into two channels: the kinetic Alfven wave cascade destined to be dissipated into electron heat and the ion entropy cascade, resulting in ion heating. The phase-space nature of the cascade is particularly manifest in this case as the ion entropy cascade involves simultaneous generation of small spatial scales and small scales in velocity space, the latter via a nonlinear phase-mixing process due to ion gyromotion. I will also discuss how the electron Landau damping and the associated process of parallel phase mixing fit into this cascade picture and whether they represent an effective dissipation mechanism in a strongly turbulent nonlinear system.

Schekochihin, A.; Cowley, S.; Dorland, W.; Howes, G. G.; Quataert, E.; Tatsuno, T.; Plunk, G.; TenBarge, J.; Mallet, A.; Kanekar, A.

2011-12-01

413

Reduction of vortex shedding intensity from a cylinder using semi-active flow control  

NASA Astrophysics Data System (ADS)

Experiments were performed in the open water channel at the Waterpower Laboratory, NTNU, Norway, with the aim of reducing vortex shedding intensity by semi-active flow control. The test rig consisted of a perforated steel tube lined by a rubber bellows. The holes (d/D=0.6) formed a line at the leading edge, one tube diameter apart. Two flow control modes were attainable; (1) lining being flush with the cylinder wall, and (2) pressurized lining creating leading edge bumps. Upstream flow conditions were monitored, and used as input for the control loop governing the pressure of the lining. A flat metal rod, onto which strain gauges were glued, was positioned in the wake. It was assumed that the motion of the rod corresponded to the velocity components normal to the main flow direction. Thus the motion of the rod described the vortex shedding from the tube. Strouhal numbers were found to be approximately 0.3. It was the assumption that the bumps would disrupt vortex formation and reduce the vortex intensity. Tests showed that the assumption was plausible, with observed intensity reductions of 15-30% for ReD ˜ [20000 to 50000]. Plots also appear to show a breakdown of organization in the wake when the tube is in activated mode. It was shown that semi-active control of vortex shedding behind a cylinder is achievable.

Ekanger, Jarle V.; Kjeldsen, Morten

2011-11-01

414

Meridional Flow Variations in Cycles 23 and 24: Active Latitude Control of Sunspot Cycle Amplitudes  

NASA Technical Reports Server (NTRS)

We have measured the meridional motions of magnetic elements observed in the photosphere over sunspot cycles 23 and 24 using magnetograms from SOHO/MDI and SDO/HMI. Our measurements confirm the finding of Komm, Howard, and Harvey (1993) that the poleward meridional flow weakens at cycle maxima. Our high spatial and temporal resolution analyses show that this variation is in the form of a superimposed inflow toward the active latitudes. This inflow is weaker in cycle 24 when compared to the inflow in 23, the stronger cycle. This systematic modulation of the meridional flow can modulate the amplitude of the following sunspot cycle through its influence on the Sun's polar fields.

Hathaway, David H.; Upton, Lisa

2013-01-01

415

The Impact of Neighbourhood Density on the Energy Demand of Passive Houses and on Potential Energy Sources from the Waste Flows and Solar Energy  

NASA Astrophysics Data System (ADS)

This study demonstrates how the density of a neighbourhood affects its energy demand, metabolism (energy and material flows) and its ability to produce its own energy. Single-family detached houses and row townhouses were each modeled using passive solar housing guidelines with the DesignBuilder building energy simulation software. Energy demand is then modeled within neighbourhoods at two densities based on south facing windows fully un-shaded at 9:00 am, and 12:00 pm solar time on Dec. 21. The neighbourhood metabolisms were then calculated based on location and density. The potential energy supply was evaluated from the spatial characteristics of the neighbourhood (for solar) and the metabolism (municipal solid waste and wastewater flows.) The potential energy demand and supply are then compared for the varying building types and densities to determine the sensitivity of the energy supply and demand relationships.

Stupka, Robert

416

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

417

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

NASA Technical Reports Server (NTRS)

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

Liu, Y.; Schuck, P. W.

2012-01-01

418

Redistributing energy flow and polarization of a focused azimuthally polarized beam with rotationally symmetric sector-shaped obstacles.  

PubMed

The redistribution of transversal energy flow and polarization in the focal field are represented by obstructing an azimuthally polarized beam with rotationally symmetric sector-shaped obstacles. Several energy flow rings that can finally transport the absorptive particles into fixed locations are formed in the focal plane. Furthermore, the local polarization state of the focal field is also modified by use of the rotationally symmetric obstacles. This kind of energy flow may have wide applications in optical trapping and manipulation. PMID:22446217

Jiao, Xiangyang; Liu, Sheng; Wang, Qian; Gan, Xuetao; Li, Peng; Zhao, Jianlin

2012-03-15

419

Energy flow in Branchiura sowerbyi (Oligochaeta: tubificidae) in a shallow macrophyte-dominated lake, Biandantang Lake  

Microsoft Academic Search

The energy flow ofBranchiura sowerbyi was studied for the first time in China in a shallow macrophytic lake, Biandantang Lake, Hubei Province. The energy flow\\u000a was calculated from the measurement of flesh production (12.5241kJ\\/m2a), egestion (517.7302kJ\\/m2a), metabolism (38.3273 kJ\\/m2a), and excretion (4.3798kJ\\/m2a). The net growth efficiency of the species is about 22.7%, which accords well with the generally reported value

Yan Yunjun; Liang Yanling

2004-01-01

420

Turbulence energy and diffusion transport in a separating and reattaching flow  

NASA Technical Reports Server (NTRS)

For accurate prediction of the turbulent flow in separated and reattaching regions, it is necessary to incorporate the second- and third-moments of turbulent fluctuations. The turbulence energy and the energy dissipation rate equations are modified by incorporating the second-order closure. Moreover, the third-order closure with near-wall correction is developed for the evaluation of the diffusive action of the second-moments. After comparison of the results with experimental data, it is shown that the models developed here improve the prediction of triple-velocity correlations in both recirculating and developing flow regions.

Amano, R. S.; Goel, P.

1986-01-01

421

Turbulence energy and diffusion transport of third-moments in a separating and reattaching flow  

NASA Technical Reports Server (NTRS)

For accurate prediction of turbulent flow in separated and reattaching regions, it is necessary to incorporate second- and third-moments of turbulent fluctuations. The turbulence energy and the energy dissipation rate equations are modified by incorporating second-order closure. Moreover, a transport equation model for the third-order closure with a near-wall correction is developed for the evaluation of the diffusive action of the second-moments. After comparison of the results with experimental data, it is concluded that the models developed here improve the prediction of triple-velocity correlations in both recirculating and redeveloping flow regions.

Amano, R. S.; Chai, J. C.; Goel, P.

1988-01-01

422

Momentum-energy transport from turbulence driven by parallel flow shear  

SciTech Connect

The low frequency E {times} B turbulence driven by the shear in the mass flow velocity parallel to the magnetic field is studied using the fluid theory in a slab configuration with magnetic shear. Ion temperature gradient effects are taken into account. The eigenfunctions of the linear instability are asymmetric about the mode rational surfaces. Quasilinear Reynolds stress induced by such asymmetric fluctuations produces momentum and energy transport across the magnetic field. Analytic formulas for the parallel and perpendicular Reynolds stress, viscosity and energy transport coefficients are given. Experimental observations of the parallel and poloidal plasma flows on TEXT-U are presented and compared with the theoretical models.

Dong, J.Q.; Horton, W.; Bengtson, R.D.; Li, G.X. [Univ. of Texas, Austin, TX (United States)

1994-04-01

423

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

424

Material and energy flows in the materials production, assembly, and end-of-life stages of the automotive lithium-ion battery life cycle  

Microsoft Academic Search

This document contains material and energy flows for lithium-ion batteries with an active cathode material of lithium manganese oxide (LiMnâOâ). These data are incorporated into Argonne National Laboratory's Greenhouse gases, Regulated Emissions, and Energy use in Transportation (GREET) model, replacing previous data for lithium-ion batteries that are based on a nickel\\/cobalt\\/manganese (Ni\\/Co\\/Mn) cathode chemistry. To identify and determine the mass

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

2012-01-01

425

Active-distributed temperature sensing to continuously quantify vertical flow in boreholes  

NASA Astrophysics Data System (ADS)

show how a distributed borehole flowmeter can be created from armored Fiber Optic cables with the Active-Distributed Temperature Sensing (A-DTS) method. The principle is that in a flowing fluid, the difference in temperature between a heated and unheated cable is a function of the fluid velocity. We outline the physical basis of the methodology and report on the deployment of a prototype A-DTS flowmeter in a fractured rock aquifer. With this design, an increase in flow velocity from 0.01 to 0.3 m s-1 elicited a 2.5°C cooling effect. It is envisaged that with further development this method will have applications where point measurements of borehole vertical flow do not fully capture combined spatiotemporal dynamics.

Read, T.; Bour, O.; Selker, J. S.; Bense, V. F.; Borgne, T. Le; Hochreutener, R.; Lavenant, N.

2014-05-01

426

Mitigation of Autoignition Due to Premixing in a Hypervelocity Flow Using Active Wall Cooling  

NASA Technical Reports Server (NTRS)

Preinjection of fuel on the forebody of an airbreathing vehicle is a proposed method to gain access to hypervelocity flight Mach numbers. However, this creates the possibility of autoignition either near the wall or in the core of the flow, thereby consuming fuel prematurely as well as increasing the amount of pressure drag on the vehicle. The computational fluid dynamics code VULCAN was used to conduct three dimensional simulations of the reacting flow in the vicinity of hydrogen injectors on a flat plate at conditions relevant to a Mach 12 notional flight vehicle forebody to determine the location where autoignition occurs. Active wall cooling strategies were formulated and simulated in response to regions of autoignition. It was found that tangential film cooling using hydrogen or helium were both able to nearly or completely eliminate wall autoignition in the flow domain of interest.

Axdahl, Erik; Kumar, Ajay; Wilhite, Alan

2013-01-01

427

Quantum localization, dephasing and vibrational energy flow in a trans-formanilide (TFA)-H 2O complex  

NASA Astrophysics Data System (ADS)

Recent stimulated emission pumping-population transfer spectroscopic studies are providing measurements of energy barriers to hydrogen bond rearrangements involving biological molecules and water. To determine the kinetics of hydrogen bond rearrangements we need in addition information about energy flow in the biomolecule-water complex. We address the problem of quantum energy flow in one such complex system using a random matrix approach. We report here calculations of energy flow in the peptide trans-formanilide (TFA) that account for the hydrogen bonding of a water molecule to one of two sites on the peptide. Coupling to the water is found to enhance energy flow in the peptide. At energies near the hydrogen bond rearrangement barrier the rate of energy flow in TFA is nevertheless sufficiently sluggish to have a significant impact on the kinetics of water shuttling between hydrogen-bonding sites.

Agbo, Johnson K.; Jain, Amber; Leitner, David M.

2010-08-01

428

Geophysical investigations at Stromboli volcano, Italy: implications for ground water flow and paroxysmal activity  

NASA Astrophysics Data System (ADS)

Stromboli volcano (Italy) is characterized by a permanent mild explosive activity disrupted by major and paroxysmal eruptions. These strong eruptions could be triggered by phreato-magmatic processes. With the aim of obtaining a better understanding of ground water flow in the vicinity of the active vents, we carried out a set of geophysical measurements along two profiles crossing the Fossa area (through the Pizzo, the Large and the Small Fossa craters). These measurements include electrical resistivity, induced polarization, self-potential, temperature and CO2 ground concentration. These methods are used in order to delineate the crater boundaries, which act as preferential fluid flow pathways for the upflow of hydrothermal fluids. The absence of fumarolic activity in the Fossa area and the ground temperature close to 100 °C at a depth of 30 cm indicate that the hydrothermal fluids condense close to the ground surface. Part of this condensed water forms a shallow drainage network (<20 m) in which groundwater flows downslope toward a perched aquifer. The piezometric surface of this aquifer is located ~20 m below the topographic low of the Small Fossa crater and is close (<100 m) to the active vents. Electrical resistivity tomography, temperature and CO2 measurements show that this shallow aquifer separates the underlying hydrothermal body from the ground surface. Further studies are needed to ascertain the size of this aquifer and to check its possible implications for the major and paroxysmal events observed at the Stromboli volcano.

Revil, A.; Finizola, A.; Sortino, F.; Ripepe, M.

2004-04-01

429

The study of surface-active element oxygen on flow patterns and penetration in A-TIG welding  

NASA Astrophysics Data System (ADS)

A three-dimensional mathematical model was developed to simulate the flow patterns and temperature distributions in a moving A-TIG weld pool of 304 stainless steels with different oxygen content using PHOENICS software. It is shown that the surface-active element, oxygen, is important, because it affects the weld shape by changing the flow patterns in the weld pool. The weld bead penetration and the depth/width ratio increase first sharply and then remain nearly a constant with increasing oxygen content. Depending upon the oxygen contents, three, one, or two vortexes that have different positions, strength, and directions may be found in the weld pool. Oxygen can cause significant changes in the weld shape by varying the sign of the surface tension coefficient. The situation with the maximum surface tension moves from the edge to the center with increasing oxygen content. As oxygen content exceeds a critical value, a positive surface tension coefficient dominates the flow patterns. The vortexes with opposite directions caused by positive surface tension coefficient can efficiently transfer the thermal energy from the arc, creating a deep weld pool. The critical oxygen content increases with the increase of the welding current.

Zhao, Yuzhen; Shi, Yaowu; Lei, Yongping

2006-06-01

430

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

Microsoft Academic Search

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

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

431

Lumbar sympathetic nerve activity and hindquarter blood flow during REM sleep in rats  

PubMed Central

The present study aimed to investigate the response of lumbar sympathetic nerve activity (LSNA) to the onset of rapid eye movement (REM) sleep and its contribution to the regulation of muscle blood flow during REM sleep in rats. Electrodes for the measurements of LSNA, electroencephalogram, electromyogram and electrocardiogram and a Doppler flow cuff for the measurements of blood flow in the common iliac and mesenteric arteries, also catheters for the measurements of systemic arterial and central venous pressures were implanted chronically. REM sleep resulted in a step increase in LSNA, by 22 ± 9% (mean ±s.e.m., P < 0.05), a reduction of iliac vascular conductance, by ?16 ± 3% (P < 0.05) and a gradual increase in systemic arterial pressure, reaching a maximum value of 8.1 ± 2.0 mmHg (P < 0.05) at 89 s after onset of REM sleep, while mesenteric vascular conductance increased simultaneously by 5 ± 2% (P < 0.05). There was a significant (Pearson's correlation coefficient = 0.94, P < 0.05) inverse linear relationship between LSNA and the iliac blood flow. Unilateral lumbar sympathectomy blunted the reduction of iliac blood flow induced by the onset of REM sleep. The present observations suggest that the onset of REM sleep appears to be associated with a vasodilation in viscera and a vasoconstriction in skeletal muscle, such that systemic arterial pressure increases during REM sleep in rats.

Miki, Kenju; Oda, Michiyo; Kamijyo, Nozomi; Kawahara, Kazumi; Yoshimoto, Misa

2004-01-01

432

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

433

Reduced cerebral blood flow with orthostasis precedes hypocapnic hyperpnea, sympathetic activation, and postural tachycardia syndrome.  

PubMed

Hyperventilation and reduced cerebral blood flow velocity can occur in postural tachycardia syndrome (POTS). We studied orthostatically intolerant patients, with suspected POTS, with a chief complaint of upright dyspnea. On the basis of our observations of an immediate reduction of cerebral blood flow velocity with orthostasis, we hypothesize that the resulting ischemic hypoxia of the carotid body causes chemoreflex activation, hypocapnic hyperpnea, sympathetic activation, and increased heart rate and blood pressure in this subset of POTS. We compared 11 dyspneic POTS subjects with 10 healthy controls during a 70° head-up tilt. In POTS subjects during initial orthostasis before blood pressure recovery; central blood volume and mean arterial pressure were reduced (P<0.025), resulting in a significant (P<0.001) decrease in cerebral blood flow velocity, which temporally preceded (17±6 s; P<0.025) a progressive increase in minute ventilation and decrease in end tidal CO2 (P<0.05) when compared with controls. Sympathoexcitation, measured by muscle sympathetic nerve activity, was increased in POTS (P<0.01) and inversely proportional to end tidal CO2 and resulted in an increase in heart rate (P<0.001), total peripheral resistance (P<0.025), and a decrease in cardiac output (P<0.025). The decrease in cerebral blood flow velocity and mean arterial pressure during initial orthostasis was greater (P<0.025) in POTS. Our data suggest that exaggerated initial central hypovolemia during initial orthostatic hypotension in POTS results in reduced cerebral blood flow velocity and postural hypocapnic hyperpnea that perpetuates cerebral ischemia. We hypothesize that sustained hypocapnia and cerebral ischemia produce sympathoexcitation, tachycardia, and a statistically significant increase in blood pressure. PMID:24711524

Del Pozzi, Andrew T; Schwartz, Christopher E; Tewari, Deepali; Medow, Marvin S; Stewart, Julian M

2014-06-01

434

Active Control of Panel Vibrations Induced by a Boundary Layer Flow  

NASA Technical Reports Server (NTRS)

In recent years, active and passive control of sound and vibration in aeroelastic structures have received a great deal of attention due to many potential applications to aerospace and other industries. There exists a great deal of research work done in this area. Recent advances in the control of sound and vibration can be found in the several conference proceedings. In this report we will summarize our research findings supported by the NASA grant NAG-1-1175. The problems of active and passive control of sound and vibration has been investigated by many researchers for a number of years. However, few of the articles are concerned with the sound and vibration with flow-structure interaction. Experimental and numerical studies on the coupling between panel vibration and acoustic radiation due to flow excitation have been done by Maestrello and his associates at NASA/Langley Research Center. Since the coupled system of nonlinear partial differential equations is formidable, an analytical solution to the full problem seems impossible. For this reason, we have to simplify the problem to that of the nonlinear panel vibration induced by a uniform flow or a boundary-layer flow with a given wall pressure distribution. Based on this simplified model, we have been able to study the control and stabilization of the nonlinear panel vibration, which have not been treated satisfactorily by other authors. The vibration suppression will clearly reduce the sound radiation power from the panel. The major research findings will be presented in the next three sections. In Section II we shall describe our results on the boundary control of nonlinear panel vibration, with or without flow excitation. Section III is concerned with active control of the vibration and sound radiation from a nonlinear elastic panel. A detailed description of our work on the parametric vibrational control of nonlinear elastic panel will be presented in Section IV. This paper will be submitted to the Journal of Acoustic Society of America for publication.

Chow, Pao-Liu

1998-01-01

435

Studying Temperature Variations at Active Volcanoes to Create a Proxy for Mass Flow  

NASA Astrophysics Data System (ADS)

Heat transfer is involved in virtually all stages of volcanic activity. As heat transfer is strongly coupled to mass flow, it can be used as a much more direct indicator of volcanic activity than is generally available. Finite difference and finite element models of simple fracture flow allow temperature variations measured at the surface to be directly linked to mass flow variations. Refinements and improvements to the models are suggested by comparison with temperature data but show that a simple relationship is essentially valid. We have deployed dataloggers at fracture zones on active volcanoes in Ecuador and Nicaragua to record temperature, atmospheric pressure, CO2 flux, self-potential, seismicity and rainfall. Analysis of these data sets suggest that pressure can have a strong effect on temperature, and variations are also seen related to rainfall. Using a data-base deterministic approach, external forcing factors can be separated from internal changes in pressure and show that in some cases there are variations that are not clearly related to any of the other recorded data, and so are most likely due to internal changes in mass flow from the volcano. A correlation was found between an eruption at Telica volcano and changes in temperature. At Masaya volcano transient variations in temperature of up to 40 degrees celsius were attributed to rapid changes in degassing. New improvements in technology allow dataloggers to be installed and high resolution data to be recorded relatively cheaply. Changes in temperature with depth and lateral changes can be measured and modeled to provide a proxy for mass flow at depth. Therefore there is an exciting possibility of using this as a new monitoring tool.

Pearson, S. C.; Connor, C. B.; Sanford, W.; Lehto, H.; Mothes, P.; Strauch, W.; Young, P.; Rivero, D.; Saballos, A.

2006-12-01

436

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

437

Experimental Study of Active Path Block in a Multi-Bifurcated Flow by Microbubble Aggregation  

NASA Astrophysics Data System (ADS)

We previously reported our attempts at the active control of microbubble aggregations using acoustic radiation force, which propels microbubbles and adjusts the size of aggregations. However, because we used simple-shape artificial blood vessels, the behavior of aggregations in a small channel, e.g., the probability to obstruct the bloodstream, and the possibility of embolization, has not been predicted. Thus, we designed and fabricated a multi-bifurcated artificial blood vessel to apply to the production and active control of microbubble aggregations. Then, we introduced two kinds of ultrasound transducers for producing and propelling aggregations. First, we produced aggregations in a flow to measure their size and investigate their variation according to the emission duration of ultrasound. Then, we control the aggregations in an artificial blood vessel to verify their controllability. When ultrasound was stopped, the aggregations flaked off the vessel wall and flowed downstream, were propelled to the desired path, and finally were caught at a narrow path. We verified the same experiment under similar parameters to calculate the probability of realizing a path block. When the flow velocity was 20 mm/s, almost 50% of the aggregations were induced to flow through the desired path and a maximum probability of realizing a path block of 86% was achieved with the formation of aggregations.

Shigehara, Nobuhiko; Demachi, Fumi; Koda, Ren; Mochizuki, Takashi; Masuda, Kohji; Ikeda, Seiichi; Arai, Fumihito; Miyamoto, Yoshitaka; Chiba, Toshio

2013-07-01

438

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

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